Gauging interest of the general public in laser-assisted in situ keratomileusis eye surgery.

PubMed

Stein, Joshua D; Childers, David M; Nan, Bin; Mian, Shahzad I

2013-07-01

To assess interest among members of the general public in laser-assisted in situ keratomileusis (LASIK) surgery and how levels of interest in this procedure have changed over time in the United States and other countries. Using the Google Trends Web site, we determined the weekly frequency of queries involving the term "LASIK" from January 1, 2007, through January 1, 2011, in the United States, United Kingdom, Canada, and India. We fit separate regression models for each of the countries to assess whether residents of these countries differed in their querying rates on specific dates and over time. Similar analyses were performed to compare 4 US states. Additional regression models compared general public interest in LASIK surgery before and after the release of a 2008 Food and Drug Administration report describing complaints associated with this procedure. During 2007 to 2011, the Google query rate for "LASIK" was highest among persons residing in India, followed by the United Kingdom, Canada, and the United States. During this time period, the query rate declined by 40% in the United States, 24% in India, and 22% in the United Kingdom, and it increased by 8% in Canada. In all 4 of the US states examined, the query rate declined-by 52% in Florida, 56% in New York, 54% in Texas, and 42% in California. Interest in LASIK declined further among US citizens after the Food and Drug Administration report release. Interest among the general public in LASIK surgery has been waning in recent years.

Laser-assisted in-situ keratomileusis (LASIK) versus photorefractive keratectomy (PRK) for myopia.

PubMed

Shortt, Alex J; Allan, Bruce D S; Evans, Jennifer R

2013-01-31

Myopia (also known as short-sightedness or near-sightedness) is an ocular condition in which the refractive power of the eye is greater than is required, resulting in light from distant objects being focused in front of the retina instead of directly on it. The two most commonly used surgical techniques to permanently correct myopia are photorefractive keratectomy (PRK) and laser-assisted in-situ keratomileusis (LASIK). To compare the effectiveness and safety of LASIK and PRK for correction of myopia by examining post-treatment uncorrected visual acuity, refractive outcome, loss of best spectacle-corrected visual acuity, pain scores, flap complications in LASIK, subepithelial haze, adverse events, quality of life indices and higher order aberrations. We searched CENTRAL (which contains the Cochrane Eyes and Vision Group Trials Register) (The Cochrane Library 2012, Issue 11), Ovid MEDLINE, Ovid MEDLINE In-Process and Other Non-Indexed Citations, Ovid MEDLINE Daily, Ovid OLDMEDLINE (January 1946 to November 2012), EMBASE (January 1980 to November 2012), Latin American and Caribbean Literature on Health Sciences (LILACS) (January 1982 to November 2012), the metaRegister of Controlled Trials (mRCT) (www.controlled-trials.com), ClinicalTrials.gov (www.clinicaltrials.gov) and the WHO International Clinical Trials Registry Platform (ICTRP) (www.who.int/ictrp/search/en). We did not use any date or language restrictions in the electronic searches for trials. We last searched the electronic databases on 15 November 2012. We also searched the reference lists of the studies and the Science Citation Index. We included randomised controlled trials comparing LASIK and PRK for the correction of any degree of myopia. Two authors independently assessed trial quality and extracted data. We summarised data using the odds ratio and mean difference. We combined odds ratios using a random-effects model after testing for heterogeneity. We included 13 trials (1135 participants, 1923 eyes

Photorefractive keratectomy (PRK) versus laser-assisted in-situ keratomileusis (LASIK) for myopia.

PubMed

Shortt, A J; Allan, B D S

2006-04-19

Myopia (also known as short-sightedness or near-sightedness) is an ocular condition in which the refractive power of the eye is greater than is required, resulting in light from distant objects being focused in front of the retina instead of directly on it. The two most commonly used surgical techniques to permanently correct myopia are photorefractive keratectomy (PRK) and laser-assisted in-situ keratomileusis (LASIK). The aim of this review was to compare the effectiveness and safety of PRK and LASIK for correction of myopia. We searched the Cochrane Central Register of Controlled Trials (CENTRAL) in The Cochrane Library (2005, Issue 3), MEDLINE (1966 to September 2005), EMBASE (1980 to September 2005) and LILACs (1982 to 3 November 2005). We also searched the reference lists of the studies and the Science Citation Index. We included randomised controlled trials comparing PRK and LASIK for correction of any degree of myopia. We also included data on adverse events from prospective multicentre consecutive case series in the Food and Drugs Administration (FDA) trials database (http//www.fda.gov/cdrh/LASIK/lasers.htm). Two authors independently assessed trial quality and extracted data. Data were summarised using odds ratio and mean difference. Odds ratios were combined using a random-effects model after testing for heterogeneity. This review included six randomised controlled trials involving a total of 417 eyes, of which 201 were treated with PRK and 216 with LASIK. We found that although LASIK gives a faster visual recovery than PRK, the effectiveness of these two procedures is comparable. We found some evidence that LASIK may be less likely than PRK to result in loss of best spectacle-corrected visual acuity. LASIK gives a faster visual recovery than PRK but the effectiveness of these two procedures is comparable. Further trials using contemporary techniques are required to determine whether LASIK and PRK are equally safe.

Epithelial ingrowth following laser in situ keratomileusis (LASIK): prevalence, risk factors, management and visual outcomes

PubMed Central

Srinivasan, Sathish; Danjoux, Jean-Pierre

2018-01-01

The number of laser in situ keratomileusis (LASIK) procedures is continuing to rise. Since its first application for correcting simple refractive errors over 25 years ago, the role of LASIK has extended to treat other conditions, including postkeratoplasty astigmatism/ametropia, postcataract surgery refractive error and presbyopia, among others. The long-term effectiveness, predictability and safety have been well established by many large studies. However, due to the creation of a potential interface between the flap and the underlying stroma, interface complications such as infectious keratitis, diffuse lamellar keratitis and epithelial ingrowth may occur. Post-LASIK epithelial ingrowth (PLEI) is an uncommon complication that usually arises during the early postoperative period. The reported incidence of PLEI ranged from 0%–3.9% in primary treatment to 10%–20% in retreatment cases. It can cause a wide spectrum of clinical presentations, ranging from asymptomatic interface changes to severe visual impairment and flap melt requiring keratoplasty. PLEI can usually be treated with mechanical debridement of the affected interface; however, additional interventions, such as alcohol, mitomycin C, fibrin glue, ocular hydrogel sealant, neodymium:yttriumaluminum garnet laser and amniotic membrane graft, may be required for recurrent or refractory cases. The aims of this review are to determine the prevalence and risk factors of PLEI; to describe its pathogenesis and clinical features and to summarise the therapeutic armamentarium and the visual outcome of PLEI. PMID:29657982

Epithelial ingrowth following laser in situ keratomileusis (LASIK): prevalence, risk factors, management and visual outcomes.

PubMed

Ting, Darren Shu Jeng; Srinivasan, Sathish; Danjoux, Jean-Pierre

2018-01-01

The number of laser in situ keratomileusis (LASIK) procedures is continuing to rise. Since its first application for correcting simple refractive errors over 25 years ago, the role of LASIK has extended to treat other conditions, including postkeratoplasty astigmatism/ametropia, postcataract surgery refractive error and presbyopia, among others. The long-term effectiveness, predictability and safety have been well established by many large studies. However, due to the creation of a potential interface between the flap and the underlying stroma, interface complications such as infectious keratitis, diffuse lamellar keratitis and epithelial ingrowth may occur. Post-LASIK epithelial ingrowth (PLEI) is an uncommon complication that usually arises during the early postoperative period. The reported incidence of PLEI ranged from 0%-3.9% in primary treatment to 10%-20% in retreatment cases. It can cause a wide spectrum of clinical presentations, ranging from asymptomatic interface changes to severe visual impairment and flap melt requiring keratoplasty. PLEI can usually be treated with mechanical debridement of the affected interface; however, additional interventions, such as alcohol, mitomycin C, fibrin glue, ocular hydrogel sealant, neodymium:yttriumaluminum garnet laser and amniotic membrane graft, may be required for recurrent or refractory cases. The aims of this review are to determine the prevalence and risk factors of PLEI; to describe its pathogenesis and clinical features and to summarise the therapeutic armamentarium and the visual outcome of PLEI.

Bilateral acute angle closure glaucoma after hyperopic LASIK correction

PubMed Central

Osman, Essam A.; Alsaleh, Ahmed A.; Al Turki, Turki; AL Obeidan, Saleh A.

2009-01-01

Acute angle closure glaucoma is unexpected complication following laser in situ keratomileusis (LASIK). We are reporting a 49-years-old lady that was presented to the emergency department with acute glaucoma in both eyes soon after LASIK correction. Diagnosis was made on detailed clinical history and examination, slit lamp examination, intraocular pressure measurement and gonioscopy. Laser iridotomy in both eyes succeeded in controlling the attack and normalizing the intraocular pressure (IOP) more than 6 months of follow-up. Prophylactic laser iridotomy is essential for narrow angle patients before LASIK surgery if refractive laser surgery is indicated. PMID:23960863

Basics of LASIK Eye Surgery

MedlinePlus

... Vea esta página en español The Basics of LASIK Eye Surgery Share This Page Facebook Twitter Linked- ... Surgery Surgical Alternatives to LASIK For More Information  LASIK Basics If you wear glasses or contact lenses, ...

LASIK and dry eye.

PubMed

Toda, Ikuko

2007-01-01

Dry eye is one of the most common complications after laser-assisted in situ keratomileusis (LASIK). The clinical signs of post-LASIK dry eye include positive vital staining of ocular surface, decreased tear film breakup time and Schirmer test, reduced corneal sensitivity, and decreased functional visual acuity. The symptoms and signs last at least 1 month after LASIK. Although the mechanisms for developing post-LASIK dry eye are not completely understood, loss of corneal innervation by flap-making may affect the reflex loops of the corneal-lacrimal gland, corneal-blinking, and blinking-meibomian gland, and blinking-meibomian gland, resulting in decreased aqueous and lipid tear secretion and mucin expression. As LASIK enhancement by flap-lifting induces less dry eye symptoms and signs than first surgery, it is suggested that other factors rather than loss of neurotrophic effect may be involved in the mechanisms of post-LASIK dry eye. The treatments of dry eye include artificial tears, topical cyclosporine, hot compress, punctal plugs, and autologous serum eye drops. For patients with severe preoperative dry eye, a combination of punctal plugs and serum eye drops is required to be used before surgery.

Small incision lenticule extraction (SMILE) versus laser in-situ keratomileusis (LASIK): study protocol for a randomized, non-inferiority trial.

PubMed

Ang, Marcus; Tan, Donald; Mehta, Jodhbir S

2012-05-31

Small incision lenticule extraction or SMILE is a novel form of 'flapless' corneal refractive surgery that was adapted from refractive lenticule extraction (ReLEx). SMILE uses only one femtosecond laser to complete the refractive surgery, potentially reducing surgical time, side effects, and cost. If successful, SMILE could potentially replace the current, widely practiced laser in-situ keratomileusis or LASIK. The aim of this study is to evaluate whether SMILE is non-inferior to LASIK in terms of refractive outcomes at 3 months post-operatively. Single tertiary center, parallel group, single-masked, paired-eye design, non-inferiority, randomized controlled trial. Participants who are eligible for LASIK will be enrolled for study after informed consent. Each participant will be randomized to receive SMILE and LASIK in each eye. Our primary hypothesis (stated as null) in this non-inferiority trial would be that SMILE differs from LASIK in adults (>21 years old) with myopia (> -3.00 diopter (D)) at a tertiary eye center in terms of refractive predictability at 3 months post-operatively. Our secondary hypothesis (stated as null) in this non-inferiority trial would be that SMILE differs from LASIK in adults (>21 years old) with myopia (> -3.00 D) at a tertiary eye center in terms of other refractive outcomes (efficacy, safety, higher-order aberrations) at 3 months post-operatively. Our primary outcome is refractive predictability, which is one of several standard refractive outcomes, defined as the proportion of eyes achieving a postoperative spherical equivalent (SE) within ±0.50 D of the intended target. Randomization will be performed using random allocation sequence generated by a computer with no blocks or restrictions, and implemented by concealing the number-coded surgery within sealed envelopes until just before the procedure. In this single-masked trial, subjects and their caregivers will be masked to the assigned treatment in each eye. This novel

Small incision lenticule extraction (SMILE) versus laser in-situ keratomileusis (LASIK): study protocol for a randomized, non-inferiority trial

PubMed Central

2012-01-01

Background Small incision lenticule extraction or SMILE is a novel form of ‘flapless’ corneal refractive surgery that was adapted from refractive lenticule extraction (ReLEx). SMILE uses only one femtosecond laser to complete the refractive surgery, potentially reducing surgical time, side effects, and cost. If successful, SMILE could potentially replace the current, widely practiced laser in-situ keratomileusis or LASIK. The aim of this study is to evaluate whether SMILE is non-inferior to LASIK in terms of refractive outcomes at 3 months post-operatively. Methods/Design Single tertiary center, parallel group, single-masked, paired-eye design, non-inferiority, randomized controlled trial. Participants who are eligible for LASIK will be enrolled for study after informed consent. Each participant will be randomized to receive SMILE and LASIK in each eye. Our primary hypothesis (stated as null) in this non-inferiority trial would be that SMILE differs from LASIK in adults (>21 years old) with myopia (> −3.00 diopter (D)) at a tertiary eye center in terms of refractive predictability at 3 months post-operatively. Our secondary hypothesis (stated as null) in this non-inferiority trial would be that SMILE differs from LASIK in adults (>21 years old) with myopia (> −3.00 D) at a tertiary eye center in terms of other refractive outcomes (efficacy, safety, higher-order aberrations) at 3 months post-operatively. Our primary outcome is refractive predictability, which is one of several standard refractive outcomes, defined as the proportion of eyes achieving a postoperative spherical equivalent (SE) within ±0.50 D of the intended target. Randomization will be performed using random allocation sequence generated by a computer with no blocks or restrictions, and implemented by concealing the number-coded surgery within sealed envelopes until just before the procedure. In this single-masked trial, subjects and their caregivers will be masked to the assigned

One year follow-up of contrast sensitivity following conventional laser in situ keratomileusis and laser epithelial keratomileusis.

PubMed

Townley, Deirdre; Kirwan, Caitriona; O'Keefe, Michael

2012-02-01

To determine the effect of conventional laser in situ keratomileusis (LASIK) and laser epithelial keratomileusis (LASEK) for myopia on contrast sensitivity (CS) using the Pelli-Robson and Vector Vision CSV-1000E CS tests. A prospective, comparative study was conducted on 36 eyes of 36 patients with myopia undergoing LASIK (18 eyes) and LASEK (18 eyes). Surgery was performed using the Technolas 217z laser (Bausch & Lomb). CS was recorded preoperatively and at 3, 6 and 12 months postoperatively. No statistically significant difference was found in LogMAR uncorrected visual acuity post-LASIK (-0.02 ± 0.16) and LASEK (-0.04 ± 0.14). Using the Pelli-Robson, CS was significantly lower in the LASIK group 3 and 6 months postoperatively. No significant postoperative reduction in CS was observed in either treatment group. Using the CSV-1000E test, CS was significantly reduced post-LASIK at 3 (p = 0.05) and 6 (p = 0.05) cycles/degree under photopic conditions. No significant postoperative change occurred in the LASEK group under photopic or scotopic conditions. There was no significant difference in postoperative CS between the LASIK and LASEK groups at 3, 6, 12 or 18 cycles/degree using the CSV-1000E test. One year postoperatively, there was no difference in CS between both treatment groups using the Pelli-Robson and CSV-1000E tests. CS was reduced postoperatively in the LASIK group at the lower spatial frequencies under photopic conditions. No postoperative change was detected in CS following LASIK or LASEK using the Pelli-Robson test. © 2010 The Authors. Journal compilation © 2010 Acta Ophthalmol.

Refractive regression after laser in situ keratomileusis.

PubMed

Yan, Mabel K; Chang, John Sm; Chan, Tommy Cy

2018-04-26

Uncorrected refractive errors are a leading cause of visual impairment across the world. In today's society, laser in situ keratomileusis (LASIK) has become the most commonly performed surgical procedure to correct refractive errors. However, regression of the initially achieved refractive correction has been a widely observed phenomenon following LASIK since its inception more than two decades ago. Despite technological advances in laser refractive surgery and various proposed management strategies, post-LASIK regression is still frequently observed and has significant implications for the long-term visual performance and quality of life of patients. This review explores the mechanism of refractive regression after both myopic and hyperopic LASIK, predisposing risk factors and its clinical course. In addition, current preventative strategies and therapies are also reviewed. © 2018 Royal Australian and New Zealand College of Ophthalmologists.

Plasma Rich in Growth Factors for the Treatment of Dry Eye after LASIK Surgery.

PubMed

Sanchez-Avila, Ronald Mauricio; Merayo-Lloves, Jesus; Fernandez, Maria Laura; Rodriguez-Gutierrez, Luis Alberto; Jurado, Nancy; Muruzabal, Francisco; Orive, Gorka; Anitua, Eduardo

2018-06-08

The aim of this study was to evaluate the use of plasma rich in growth factors (PRGF) eye drops in patients with dry eye disease after laser-assisted in situ keratomileusis (LASIK) surgery. This is a longitudinal, retrospective, comparative, and descriptive study of 77 eyes of 42 patients with dry eye disease following LASIK surgery. This study was designed to evaluate the efficacy of PRGF treatment compared to conventional therapy (control group). Outcome measures including signs and symptoms of dry eye disease were evaluated before and after treatment. The percentage of change before and after treatment for each clinical variable measured was compared between both groups. There were 1-4 treatment cycles with PRGF eye drops (1 cycle = 6 weeks). Results showed a statistically significant improvement in the Ocular Surface Disease Index (38.12%), visual analogue scale scores for frequency (41.89%) and severity (42.47%), and the Schirmer test scores (88.98%) after PRGF treatment (p < 0.05). No adverse events were reported after PRGF treatment. These results suggest that PRGF eye drops are effective for the improvement of dry eye symptoms in patients who underwent LASIK surgery in comparison to the conventional therapy. The treatment with PRGF is an alternative for patients who suffer from postoperative dry eye. © 2018 S. Karger AG, Basel.

Safety, efficacy, predictability and stability of laser in situ keratomileusis (LASIK) with a 1000-Hz scanning spot excimer laser.

PubMed

Khoramnia, Ramin; Salgado, Josefina P; Wuellner, Christian; Donitzky, Christof; Lohmann, Chris P; Winkler von Mohrenfels, Christoph

2012-09-01

To evaluate the safety, efficacy, predictability and stability of laser in situ keratomileusis (LASIK) with a 1000-Hz scanning spot excimer laser (Concept System 1000; WaveLight GmbH, Erlangen, Germany). LASIK was performed on twenty eyes with myopia or myopic astigmatism (mean spherical equivalent refraction: -3.97±1.72 dioptres (D); mean cylinder: -0.84±0.77 D) using a microkeratome for flap creation and the Concept System 1000 for photoablation. Patients were examined preoperatively as well as 1, 3 and 6 months after the treatment. Manifest sphere and cylinder, uncorrected (UCDVA) and best corrected (BCDVA) distance visual acuity, corneal topography and pachymetry were analysed. We observed no adverse events that might have been associated with the use of a repetition rate of 1000 Hz. All eyes maintained or had improved BCDVA at 6 months after treatment when compared to preoperative values. Six months after LASIK, UCDVA was 20/20 or better in 85% and 20/25 or better in 100% of the eyes. The spherical equivalent refraction was within ±0.50 D in 95% of the eyes at 6 months after surgery. The refraction stayed stable over time; 95% of the eyes changed<0.5 D postoperatively. LASIK with the prototype 1000-Hz excimer laser was safe, efficient and predictable. The postoperative refraction was stable over time. There were no specific clinical side-effects that might be associated with the use of such a high repetition rate. © 2011 The Authors. Acta Ophthalmologica © 2011 Acta Ophthalmologica Scandinavica Foundation.

Photorefractive keratectomy (PRK) versus laser assisted in situ keratomileusis (LASIK) for hyperopia correction.

PubMed

Settas, George; Settas, C; Minos, E; Yeung, Ian Y L

2009-04-15

Hyperopia, or hypermetropia (also known as long-sightedness or far-sightedness), is the condition where the unaccommodating eye brings parallel light to a focus behind the retina instead of on it. Hyperopia can be corrected with both non-surgical and surgical methods, among them photorefractive keratectomy (PRK) and laser assisted In situ keratomileusis (LASIK). There is uncertainty as to whether hyperopic-PRK or hyperopic-LASIK is the better method. The objectives of this review were to determine whether PRK or LASIK leads to more reliable, stable and safe results when correcting a hyperopic refractive error. We searched the Cochrane Central Register of Controlled Trials (The Cochrane Library Issue 4, 2008), MEDLINE (January 1950 to January 2009), EMBASE (January 1980 to January 2009) and LILACS (January 1982 to January 2009). There were no language or date restrictions in the search for trials. The electronic databases were last searched on 13 January 2009. We also searched the reference lists of the studies included in the review for information about further trials and used the Science Citation Index to search for papers that cite any studies included in this review. We did not handsearch journals or conference proceedings specifically for this review. We planned to include only randomised controlled trials (RCTs) comparing PRK against LASIK for correction of hyperopia and then perform a sensitivity analysis of pre- and post-millennial trials since this is the mid-point in the history of both PRK and LASIK. We did not identify any studies that met the inclusion criteria for this review. As no studies met the inclusion criteria for this review, we discussed the results of non-randomised trials comparing hyperopic-PRK with hyperopic-LASIK. No robust, reliable conclusions could be reached, but the non-randomised trials reviewed appear to be in agreement that hyperopic-PRK and hyperopic-LASIK are of comparable efficacy. High quality, well-planned open RCTs are

Review of current indications for combined very high fluence collagen cross-linking and laser in situ keratomileusis surgery

PubMed Central

Kanellopoulos, Anastasios John; Pamel, Gregory J

2013-01-01

In this brief review we will discuss the reasoning and evolution of our current use of combined very high-fluence collagen crosslinking and laser in situ keratomileusis. Several presentations and pertinent publications are reviewed, along with the key steps of the enhanced LASIK procedure. Long term outcome data support the safety and efficacy of LASIK Xtra in stabilizing myopic but also hyperopic LASIK results. In conclusion, we have compelling evidence that LASIK Xtra is a safe and effective adjunct. PMID:23925331

Early corneal nerve damage and recovery following small incision lenticule extraction (SMILE) and laser in situ keratomileusis (LASIK).

PubMed

Mohamed-Noriega, Karim; Riau, Andri K; Lwin, Nyein C; Chaurasia, Shyam S; Tan, Donald T; Mehta, Jodhbir S

2014-03-25

We compared early corneal nerve changes after small incision lenticule extraction (SMILE) and laser in situ keratomileusis (LASIK). A total of 12 rabbits underwent LASIK in one eye and SMILE in the fellow eye. Baseline and follow-up evaluations at 1, 2, and 4 weeks postoperatively were performed with in vivo confocal microscopy to evaluate 5 different areas within the treated zone: center, superior, inferior, nasal, and temporal. Cryosections of the corneas and whole mount of the extracted SMILE lenticules were analyzed with immunostaining of βIII-tubulin. One week after SMILE and LASIK, a decrease in nerve length and density was observed in all evaluated areas. A trend toward greater subbasal nerve length and density (SLD), more eyes with subbasal nerves (ESN), more eyes with subbasal nerves longer than 200 μm (SNL), and higher mean number of subbasal nerves by frame (NSN) in SMILE than in LASIK groups was observed at subsequent follow-up time points. Only the SMILE group showed a recovery of SLD, ESN, and NSN by week 4 (P > 0.05). A trend toward more eyes with sprouting subbasal nerves and greater mean number of sprouting nerves was observed in LASIK than in SMILE, indicating that more subbasal nerves were disrupted and undergoing regeneration after LASIK. Immunostaining at postoperative week 4 revealed a faster stromal nerve recovery in post-SMILE eyes compared to post-LASIK eyes. Our findings suggest that SMILE results in less nerve damage and faster nerve recovery than LASIK.

LASIK vs LASEK vs PRK: advantages and indications.

PubMed

Ambrósio, Renato; Wilson, Steven

2003-03-01

The advent of the excimer laser as an instrument for use in reshaping the corneal stroma was a great step forward in refractive surgery. Laser energy can be delivered on the stromal surface in the photorefractive keratectomy (PRK) procedure or deeper on the corneal stroma by the means of a lamellar surgery in which a flap is created with the microkeratome in the laser in situ keratomileusis (LASIK) procedure. LASIK is currently the dominant procedure in refractive surgery. The main advantage of LASIK over PRK is related to maintaining the central corneal epithelium. This increases comfort during the early post-operative period, allows for rapid visual recovery, and reduces the wound healing response. Reduced wound healing correlates with less regression for high corrections and a lower rate of complications such as significant stromal opacity (haze). PRK, however, remains as an excellent option for mild to moderate corrections, particularly for cases associated with thin corneas, recurrent erosions, or a predisposition for trauma (Martial arts, military, etc.). Recently, a modification of PRK, laser subepithelial keratomileusis (LASEK), was introduced. In the LASEK procedure, an epithelial flap is created and replaced after the ablation. The benefits, if any, of the creation of an epithelial flap compared to traditional PRK are not fully appreciated. Advocates of LASEK suggest that there is less discomfort in the early postoperative period, faster visual recovery, and less haze compared to standard PRK for correction of similar levels of refractive error. Additional long-term clinical studies, along with laboratory research, will be crucial to validate these potential advantages of LASEK procedure.

Evaluation of Biomechanical Changes in Myopia Patients with Unsatisfactory Corneas After Femto Second-Laser In Situ Keratomileusis (FS-LASIK) Concurrent with Accelerated Corneal Collagen Cross-Linking Using Corvis-ST: Two-Year Follow-Up Results.

PubMed

Xu, Weiwei; Tao, Ye; Wang, Liqiang; Huang, Yifei

2017-07-27

BACKGROUND Some myopia patients with unsatisfactory corneas consider corneal refractive surgery for different reasons. Accelerated corneal collagen crosslinking (ACXL) is an effective method to enhance the resistance of the cornea. The present investigation was designed to evaluate the changes of biomechanical properties in patients with myopia and thin corneas after femtosecond-laser in situ keratomileusis (FS-LASIK) concurrent with ACXL. MATERIAL AND METHODS A prospective study was designed. A total of 22 eyes of 11 myopia astigmatism patients with unsatisfactory corneas were enrolled. The patients were assigned to femtosecond-laser in situ keratomileusis concurrent with accelerated corneal collagen crosslinking (FS-LASIK-ACXL). The follow-up duration was 24 months. Manifest refraction, uncorrected (UDVA), and corrected distance visual acuity (CDVA), ultra-high-speed camera (Corvis-ST), corneal topography, anterior segment OCT (AS-OCT), Pentacam, and endothelial cell density (ECD) were examined before and after the operation. The corneal biomechanical and refractive data was analyzed using SAS9.3. Data were analyzed through normal distribution test and variance of analysis. The difference was considered as statistically significant when p<0.05. RESULTS The steep K (Ks) values, flat K (Kf) values, average keratometry values (Avek) values, and central corneal thickness (CCT) declined significantly after FS-LASIK-ACXL operation. The values of first applanation length (A1L), the second applanation length (A2L), the first applanation velocity (A1V), the second applanation velocity (A2V), deformation amplitude (DA), highest concavity peak distance (PD), and radius of curvature at the time of highest concavity (HCR) did not show significant difference after the operation. CONCLUSIONS FS-LASIK-ACXL is an effective and safe surgery for improving visual acuity for myopic patients with thin corneas, and it does not increase the risk of iatrogenic keratectasia.

All-femtosecond laser-assisted in situ keratomileusis

NASA Astrophysics Data System (ADS)

Gabryte, Egle; Danieliene, Egle; Vaiceliunaite, Agne; Ruksenas, Osvaldas; Vengris, Mikas; Danielius, Romualdas

2013-03-01

We present a femtosecond solid-state Yb:KGW laser system capable of performing the complete laser-assisted in situ keratomileusis (LASIK) ophthalmic procedure. The fundamental infrared radiation (IR) is used to create the corneal flap, and subsequently the corneal stromal ablation is performed using the ultraviolet (UV) pulses of the fifth harmonic. The heating of cornea, ablated surface quality, and healing outcomes of the surgeries performed using the femtosecond laser system are investigated by both ex vivo and in vivo experiments and compared to the results of conventional clinical ArF excimer laser application. The results of this research indicate the feasibility of clinical application of femtosecond UV lasers for LASIK procedure.

Peripheral Ulcerative Keratitis following Laser in situ Keratomileusis.

PubMed

Burkholder, Bryn M; Kuo, Irene C

2016-01-01

We report a case of a patient with a history of glomerulonephropathy, not disclosed prior to laser in situ keratomileusis (LASIK), who developed severe postoperative peripheral ulcerative keratitis (PUK) soon after surgery. Case report. Within a week of surgery, the patient, who had no blepharitis or ocular surface disease, also developed diffuse lamellar keratitis (DLK) that was not contiguous with the PUK. Microbiologic evaluation of the flap interface disclosed no organisms, and no epithelial ingrowth was found. Both PUK and DLK resolved with topical and oral steroid therapy, and the patient's induced refractive error improved over the 12 months following LASIK. Necrotizing keratitis has been described after LASIK surgery in patients with or without autoimmune disease. However, to our knowledge, there has been no case of PUK following LASIK. As shown by our patient's clinical course and the typical association of PUK with systemic conditions, patients with a history of atypical postinfectious sequelae may require additional preoperative counseling, vigilant postoperative monitoring, and possibly additional intervention. Because patients do not always divulge medical details, especially if an extraocular site was involved or illness occurred many years prior, this case demonstrates the importance of performing a diligent history that excludes autoimmune disorders or atypical postinfectious sequelae prior to proceeding with keratorefractive intervention.

Lasik eye surgery - slideshow

MedlinePlus

... this page: //medlineplus.gov/ency/presentations/100206.htm Lasik eye surgery - series—Normal anatomy To use the ... A.M. Editorial team. Related MedlinePlus Health Topics Laser Eye Surgery A.D.A.M., Inc. is accredited by ...

Photorefractive keratectomy (PRK) versus laser assisted in situ keratomileusis (LASIK) for hyperopia correction.

PubMed

Settas, George; Settas, Clare; Minos, Evangelos; Yeung, Ian Yl

2012-06-13

Hyperopia, or hypermetropia (also known as long-sightedness or far-sightedness), is the condition where the unaccommodating eye brings parallel light to a focus behind the retina instead of on it. Hyperopia can be corrected with both non-surgical and surgical methods, among them photorefractive keratectomy (PRK) and laser assisted In situ keratomileusis (LASIK). There is uncertainty as to whether hyperopic-PRK or hyperopic-LASIK is the better method. The objectives of this review were to determine whether PRK or LASIK leads to more reliable, stable and safe results when correcting a hyperopic refractive error. We searched CENTRAL (which contains the Cochrane Eyes and Vision Group Trials Register) (The Cochrane Library 2012, Issue 2), MEDLINE (January 1950 to February 2012), EMBASE (January 1980 to February 2012), Latin American and Caribbean Literature on Health Sciences (LILACS) (January 1982 to February 2012), the metaRegister of Controlled Trials (mRCT) (www.controlled-trials.com), ClinicalTrials.gov (www.clinicaltrials.gov) and the WHO International Clinical Trials Registry Platform (ICTRP) (www.who.int/ictrp/search/en). There were no date or language restrictions in the electronic searches for trials. The electronic databases were last searched on 17 February 2012. When trials are included in the review we will search the reference lists of the studies included in the review for information about further trials. We will use the Science Citation Index to search for papers that cite any studies included in this review. We did not handsearch journals or conference proceedings specifically for this review. We planned to include only randomised controlled trials (RCTs) comparing PRK against LASIK for correction of hyperopia and then perform a sensitivity analysis of pre- and post-millennial trials since this is the mid-point in the history of both PRK and LASIK. We did not identify any studies that met the inclusion criteria for this review. As no studies met the

Analysis of corneal endothelial cell density and morphology after laser in situ keratomileusis using two types of femtosecond lasers

PubMed Central

Tomita, Minoru; Waring, George O; Watabe, Miyuki

2012-01-01

Purpose To compare two different femtosecond lasers used for flap creation during laser-assisted in situ keratomileusis (LASIK) surgery in terms of their effects on the corneal endothelium. Methods We performed LASIK surgery on 254 eyes of 131 patients using IntraLase FS60 (Abbott Medical Optics, Inc, Irvine, CA; IntraLase group) and 254 eyes of 136 patients using Femto LDV (Ziemer Group AG, Port, Switzerland; LDV group) for corneal flap creation. The mean cell density, coefficient of variation, and hexagonality of the corneal endothelial cells were determined and the results were statistically compared. Results There were no statistically significant differences in the corneal morphology between pre and post LASIK results in each group, nor were there significant differences between the results of both groups at 3 months post LASIK. Conclusions Both IntraLase FS60 and Ziemer Femto LDV are able to create flaps without significant adverse effects on the corneal endothelial morphology through 3 months after LASIK surgery. PMID:23055680

Optical Quality, Threshold Target Identification, and Military Target Task Performance After Advanced Keratorefractive Surgery

DTIC Science & Technology

2011-05-01

WFG) photorefractive keratectomy (PRK), WFG laser in situ keratomileusis ( LASIK ), wavefront optimized (WFO) PRK or WFO LASIK (56 in each group...design will enable comparison to preoperative performance as well as comparisons between treatment groups. Military, Refractive Surgery, PRK, LASIK ...randomized treatment trial we will enroll 224 nearsighted soldiers to WFG photorefractive keratectomy (PRK), WFG LASIK , WFO PRK or WFO LASIK (56 in

Peripheral Ulcerative Keratitis following Laser in situ Keratomileusis

PubMed Central

Burkholder, Bryn M.; Kuo, Irene C.

2016-01-01

Purpose We report a case of a patient with a history of glomerulonephropathy, not disclosed prior to laser in situ keratomileusis (LASIK), who developed severe postoperative peripheral ulcerative keratitis (PUK) soon after surgery. Method Case report. Results Within a week of surgery, the patient, who had no blepharitis or ocular surface disease, also developed diffuse lamellar keratitis (DLK) that was not contiguous with the PUK. Microbiologic evaluation of the flap interface disclosed no organisms, and no epithelial ingrowth was found. Both PUK and DLK resolved with topical and oral steroid therapy, and the patient's induced refractive error improved over the 12 months following LASIK. Conclusions Necrotizing keratitis has been described after LASIK surgery in patients with or without autoimmune disease. However, to our knowledge, there has been no case of PUK following LASIK. As shown by our patient's clinical course and the typical association of PUK with systemic conditions, patients with a history of atypical postinfectious sequelae may require additional preoperative counseling, vigilant postoperative monitoring, and possibly additional intervention. Because patients do not always divulge medical details, especially if an extraocular site was involved or illness occurred many years prior, this case demonstrates the importance of performing a diligent history that excludes autoimmune disorders or atypical postinfectious sequelae prior to proceeding with keratorefractive intervention. PMID:26889153

Corneal polarimetry after LASIK refractive surgery

NASA Astrophysics Data System (ADS)

Bueno, Juan M.; Berrio, Esther; Artal, Pablo

2006-01-01

Imaging polarimetry provides spatially resolved information on the polarization properties of a system. In the case of the living human eye, polarization could be related to the corneal biomechanical properties, which vary from the normal state as a result of surgery or pathologies. We have used an aberro-polariscope, which we recently developed, to determine and to compare the spatially resolved maps of polarization parameters across the pupil between normal healthy and post-LASIK eyes. The depolarization distribution is not uniform across the pupil, with post-surgery eyes presenting larger levels of depolarization. While retardation increases along the radius in normal eyes, this pattern becomes irregular after LASIK refractive surgery. The maps of slow axis also differ in normal and post-surgery eyes, with a larger disorder in post-LASIK eyes. Since these changes in polarization indicate subtle structural modifications of the cornea, this approach can be useful in a clinical environment to follow the biomechanical and optical changes of the cornea after refractive surgery or for the early diagnosis of different corneal pathologies.

LASIK and PRK in hyperopic astigmatic eyes: is early retreatment advisable?

PubMed

Frings, Andreas; Richard, Gisbert; Steinberg, Johannes; Druchkiv, Vasyl; Linke, Stephan Johannes; Katz, Toam

2016-01-01

To analyze the refractive and keratometric stability in hyperopic astigmatic laser in situ keratomileusis (LASIK) or photorefractive keratectomy (PRK) during the first 6 months after surgery. This retrospective cross-sectional study included 97 hyperopic eyes; 55 were treated with LASIK and 42 with PRK. Excimer ablation for all eyes was performed using the ALLEGRETTO excimer laser platform using a mitomycin C for PRK and a mechanical microkeratome for LASIK. Keratometric and refractive data were analyzed during three consecutive follow-up intervals (6 weeks, 3 months, and 6 months). The corneal topography was obtained using Scheimpflug topography, and subjective refractions were acquired by expert optometrists according to a standardized protocol. After 3 months, mean keratometry and spherical equivalent were stable after LASIK, whereas PRK-treated eyes presented statistically significant (P<0.001) regression of hyperopia. In eleven cases, hyperopic regression of >1 D occurred. The optical zone diameter did not correlate with the development of regression. After corneal laser refractive surgery, keratometric changes are followed by refractive changes and they occur up to 6 months after LASIK and for at least 6 months after PRK, and therefore, caution should be applied when retreatment is planned during the 1st year after surgery because hyperopic refractive regression can lead to suboptimal visual outcome. Keratometric and refractive stability is earlier achieved after LASIK, and therefore, retreatment may be independent of late regression.

Adjuvant corneal crosslinking to prevent hyperopic LASIK regression

PubMed Central

Aslanides, Ioannis M; Mukherjee, Achyut N

2013-01-01

Purpose To report the long term outcomes, safety, stability, and efficacy in a pilot series of simultaneous hyperopic laser assisted in situ keratomileusis (LASIK) and corneal crosslinking (CXL). Method A small cohort series of five eyes, with clinically suboptimal topography and/or thickness, underwent LASIK surgery with immediate riboflavin application under the flap, followed by UV light irradiation. Postoperative assessment was performed at 1, 3, 6, and 12 months, with late follow up at 4 years, and results were compared with a matched cohort that received LASIK only. Results The average age of the LASIK-CXL group was 39 years (26–46), and the average spherical equivalent hyperopic refractive error was +3.45 diopters (standard deviation 0.76; range 2.5 to 4.5). All eyes maintained refractive stability over the 4 years. There were no complications related to CXL, and topographic and clinical outcomes were as expected for standard LASIK. Conclusion This limited series suggests that simultaneous LASIK and CXL for hyperopia is safe. Outcomes of the small cohort suggest that this technique may be promising for ameliorating hyperopic regression, presumed to be biomechanical in origin, and may also address ectasia risk. PMID:23576861

Adjuvant corneal crosslinking to prevent hyperopic LASIK regression.

PubMed

Aslanides, Ioannis M; Mukherjee, Achyut N

2013-01-01

To report the long term outcomes, safety, stability, and efficacy in a pilot series of simultaneous hyperopic laser assisted in situ keratomileusis (LASIK) and corneal crosslinking (CXL). A small cohort series of five eyes, with clinically suboptimal topography and/or thickness, underwent LASIK surgery with immediate riboflavin application under the flap, followed by UV light irradiation. Postoperative assessment was performed at 1, 3, 6, and 12 months, with late follow up at 4 years, and results were compared with a matched cohort that received LASIK only. The average age of the LASIK-CXL group was 39 years (26-46), and the average spherical equivalent hyperopic refractive error was +3.45 diopters (standard deviation 0.76; range 2.5 to 4.5). All eyes maintained refractive stability over the 4 years. There were no complications related to CXL, and topographic and clinical outcomes were as expected for standard LASIK. This limited series suggests that simultaneous LASIK and CXL for hyperopia is safe. Outcomes of the small cohort suggest that this technique may be promising for ameliorating hyperopic regression, presumed to be biomechanical in origin, and may also address ectasia risk.

Longitudinal comparison of outcomes after sub-Bowman keratomileusis and laser in situ keratomileusis: randomized, double-masked study.

PubMed

Wong, Rachel Chung Yin; Yu, Marco; Chan, Tommy C Y; Chong, Kelvin K L; Jhanji, Vishal

2015-05-01

To compare the outcomes of sub-Bowman keratomileusis (100-μm flap) and laser in situ keratomileusis (LASIK) (120-μm flap) using 150-kHz femtosecond laser. Randomized, double-masked, contralateral clinical trial. One hundred patients (200 eyes) with myopia or myopic astigmatism were included. Postoperative examinations were performed at week 1 and months 1, 3, 6, and 12. Main outcome measures included postoperative uncorrected (UCVA) and best-corrected distance visual acuity (BCVA); manifest refraction spherical equivalent; efficacy and safety indices; corneal thickness; and complications. The mean age of patients was 33.9 ± 7.9 years. Overall, the preoperative UCVA, BCVA, and manifest refraction spherical equivalent were 1.349 ± 0.332, -0.022 ± 0.033, and -5.81 ± 1.61 diopters, respectively. No significant difference was observed in preoperative (P ≥ .226) or intraoperative parameters (P ≥ .452) between both groups, except residual stromal thickness (P < .001). The UCVA, manifest refraction spherical equivalent, and central corneal thickness stabilized by 1 week, while the thinnest corneal thickness stabilized by 3 months postoperatively. There was no significant difference between both groups for any parameter during all follow-up visits (P ≥ .132) except the 3-month safety index, which was better in the sub-Bowman keratomileusis group (P = .007). Soft opaque bubble layer was noted intraoperatively in 12 cases (7, 100-μm group; 5, 120-μm group; P = .577). No postoperative complications were observed. Our study did not find any differences in the visual and refractive outcomes between femtosecond-assisted sub-Bowman keratomileusis and LASIK. Both surgeries resulted in quick visual recovery as early as 1 week postoperatively. Copyright © 2015 Elsevier Inc. All rights reserved.

Laser-assisted subepithelial keratectomy (LASEK) versus laser-assisted in-situ keratomileusis (LASIK) for correcting myopia.

PubMed

Kuryan, Jocelyn; Cheema, Anjum; Chuck, Roy S

2017-02-15

Near-sightedness, or myopia, is a condition in which light rays entering the eye along the visual axis focus in front of the retina, resulting in blurred vision. Myopia can be treated with spectacles, contact lenses, or refractive surgery. Options for refractive surgery include laser-assisted subepithelial keratectomy (LASEK) and laser-assisted in-situ keratomileusis (LASIK). Both procedures utilize a laser to shape the corneal tissue (front of the eye) to correct refractive error, and both create flaps before laser treatment of corneal stromal tissue. Whereas the flap in LASEK is more superficial and epithelial, in LASIK it is thicker and also includes some anterior stromal tissue. LASEK is considered a surface ablation procedure, much like its predecessor, photorefractive keratectomy (PRK). LASEK was developed as an alternative to PRK to address the issue of pain associated with epithelial debridement used for PRK. Assessing the relative benefits and risks/side effects of LASEK and LASIK warrants a systematic review. To assess the effects of LASEK versus LASIK for correcting myopia. We searched the Cochrane Central Register of Controlled Trials (CENTRAL), which contains the Cochrane Eyes and Vision Trials Register (2016, Issue 10); MEDLINE Ovid (1946 to 24 October 2016); Embase.com (1947 to 24 October 2016); PubMed (1948 to 24 October 2016); LILACS (Latin American and Caribbean Health Sciences Literature Database; 1982 to 24 October 2016); the metaRegister of Controlled Trials (mRCT) (www.controlled-trials.com), last searched 20 June 2014; ClinicalTrials.gov (www.clinicaltrials.gov); searched 24 October 2016; and the WHO International Clinical Trials Registry Platform (ICTRP) (www.who.int/ictrp/search/en); searched 24 October 2016. We did not use any date or language restrictions in the electronic searches for trials. We considered only randomized controlled trials (RCTs) for the purposes of this review. Eligible RCTs were those in which myopic participants were

Comparison of retina damage thresholds simulating the femtosecond-laser in situ keratomileusis (fs-LASIK) process with two laser systems in the CW- and fs-regime

NASA Astrophysics Data System (ADS)

Sander, M.; Minet, O.; Zabarylo, U.; Müller, M.; Tetz, M. R.

2012-04-01

The femtosecond-laser in situ keratomileusis procedure affords the opportunity to correct ametropia by cutting transparent corneal tissue with ultra-short laser pulses. Thereby the tissue cut is generated by a laser-induced optical breakdown in the cornea with ultra-short laser pulses in the near-infrared range. Compared to standard procedures such as photorefractive keratectomy and laser in-situ keratomileusis with the excimer laser, where the risk potential for the eye is low due to the complete absorption of ultraviolet irradiation from corneal tissue, only a certain amount of the pulse energy is deposited in the cornea during the fs-LASIK process. The remaining energy propagates through the eye and interacts with the retina and the strong absorbing tissue layers behind. The objective of the presented study was to determine and compare the retina damage thresholds during the fs-LASIK process simulated with two various laser systems in the CW- and fs-regime.

Contralateral eye comparison on changes in visual field following laser in situ keratomileusis vs photorefractive keratectomy for myopia: a randomized clinical trial.

PubMed

Mostafaei, A; Sedgipour, M R; Sadeghi-Bazargani, H

2009-12-01

Study purpose was to compare the changes of Visual Field (VF) during laser in situ Keratomileusis (LASIK) VS photorefractive keratectomy (PRK). This randomized, double blind, study involved 54 eyes of 27 Myopia patients who underwent LASIK or PRK procedures for contralateral eyes in each patient. Using Humphrey 30-2 SITA standard, the Mean Defect (MD) and Pattern Standard Deviation (PSD) were evaluated preoperatively and three months after surgery. At the same examination optical zone size, papillary and corneal diameters were also evaluated. There was no clinically significant difference in PSD and MD measurements between treated eyes with LASIK or PRK in any zone pre and postoperatively. VF may not be affected by corneal changes induced by LASIK or PRK three months after surgery.

Medical malpractice predictors and risk factors for ophthalmologists performing LASIK and PRK surgery.

PubMed Central

Abbott, Richard L

2003-01-01

PURPOSE: To identify physician predictors in laser-assisted in-situ keratomileusis (LASIK) and photorefractive keratectomy (PRK) surgery that correlate with a higher risk for malpractice liability claims and lawsuits. METHODOLOGY: A retrospective, longitudinal, cohort study comparing physician characteristics of 100 consecutive Ophthalmic Mutual Insurance Company (OMIC) LASIK and PRK claims and suits to demographic and practice pattern data for all active refractive surgeons insured by OMIC between 1996 and 2002. Background information and data were obtained from OMIC underwriting applications, a physician practice pattern survey, and claims file records. Using an outcome of whether or not a physician had a prior history of a claim or suit, logistic regression analyses were used separately for each predictor as well as controlling for refractive surgery volume. RESULTS: Logistic regression analysis demonstrated that the most important predictor of filing a claim was surgical volume, with those performing more surgery having a greater risk of incurring a claim (odds ratio [OR], 31.4 for >1,000/year versus 0 to 20/year; 95% confidence interval [CI], 7.9 - 125; P = .0001). Having one or more prior claims was the only other predictor examined that remained statistically significant after controlling for patient volume (OR, 6.4; 95% CI 2.5 - 16.4; P = .0001). Physician gender, advertising, preoperative time spent with patient, and comanagement appeared to be strong predictors in multivariate analyses when surgical volume was greater than 100 cases per year. CONCLUSION: The chances of incurring a malpractice claim or suit for PRK or LASIK correlates significantly with higher surgical volume and a history of a prior claim or suit. Additional risk factors that increase in importance with higher surgical volume include gender, advertising, preoperative time spent with patient, and comanagement with optometrists. These findings may be used in the future to help improve the

A retrospective analysis of the postoperative use of loteprednol etabonate gel 0.5% following laser-assisted in situ keratomileusis or photorefractive keratectomy surgery.

PubMed

Salinger, Clifford L; Gordon, Michael; Jackson, Mitchell A; Perl, Theodore; Donnenfeld, Eric

2015-01-01

While loteprednol etabonate ophthalmic gel 0.5% (LE gel) is approved for treatment of postoperative ocular inflammation and pain, there have been no reported studies in patients undergoing laser-assisted in situ keratomileusis (LASIK) or photorefractive keratectomy (PRK). This was a retrospective chart review conducted at five refractive surgical centers in the USA. Data were collected from primary LASIK or PRK surgery cases in which LE gel was used postoperatively as the clinician's routine standard of care and in which patients were followed-up for up to 6 months. Data extracted from charts included patient demographics, surgical details, LE gel dosing regimen, pre- and postsurgical refractive characteristics, intraocular pressure (IOP) measurements, and visual acuity. Primary outcomes included postoperative IOP elevations, adverse events, and early discontinuations. Data were collected on 189 LASIK eyes (96 patients) and 209 PRK eyes (108 patients). Mean (standard deviation [SD]) years of age at surgery was 36.0 (11.7) and 33.9 (11.3) in LASIK and PRK patients. LE gel was prescribed most often four times daily during the first postoperative week, regardless of procedure; the most common treatment duration was 7-14 days in LASIK and ≥30 days in PRK patients. No unusual corneal findings or healing abnormalities were reported. Mean postoperative uncorrected distance visual acuity was 20/24 in LASIK and 20/30 in PRK eyes. Mild/trace corneal haze was reported in 20% of PRK patients; two PRK patients with moderate/severe corneal haze were switched to another corticosteroid. Mean postoperative IOP did not increase over time in either LASIK or PRK eyes (P≥0.331); clinically significant elevations from baseline in IOP (≥10 mmHg) were noted in only three eyes of two PRK patients. LE gel appears to have a high level of safety and tolerability when used for the management of postoperative pain and inflammation following LASIK and PRK surgery.

A retrospective analysis of the postoperative use of loteprednol etabonate gel 0.5% following laser-assisted in situ keratomileusis or photorefractive keratectomy surgery

PubMed Central

Salinger, Clifford L; Gordon, Michael; Jackson, Mitchell A; Perl, Theodore; Donnenfeld, Eric

2015-01-01

Background While loteprednol etabonate ophthalmic gel 0.5% (LE gel) is approved for treatment of postoperative ocular inflammation and pain, there have been no reported studies in patients undergoing laser-assisted in situ keratomileusis (LASIK) or photorefractive keratectomy (PRK). Methods This was a retrospective chart review conducted at five refractive surgical centers in the USA. Data were collected from primary LASIK or PRK surgery cases in which LE gel was used postoperatively as the clinician’s routine standard of care and in which patients were followed-up for up to 6 months. Data extracted from charts included patient demographics, surgical details, LE gel dosing regimen, pre- and postsurgical refractive characteristics, intraocular pressure (IOP) measurements, and visual acuity. Primary outcomes included postoperative IOP elevations, adverse events, and early discontinuations. Results Data were collected on 189 LASIK eyes (96 patients) and 209 PRK eyes (108 patients). Mean (standard deviation [SD]) years of age at surgery was 36.0 (11.7) and 33.9 (11.3) in LASIK and PRK patients. LE gel was prescribed most often four times daily during the first postoperative week, regardless of procedure; the most common treatment duration was 7–14 days in LASIK and ≥30 days in PRK patients. No unusual corneal findings or healing abnormalities were reported. Mean postoperative uncorrected distance visual acuity was 20/24 in LASIK and 20/30 in PRK eyes. Mild/trace corneal haze was reported in 20% of PRK patients; two PRK patients with moderate/severe corneal haze were switched to another corticosteroid. Mean postoperative IOP did not increase over time in either LASIK or PRK eyes (P≥0.331); clinically significant elevations from baseline in IOP (≥10 mmHg) were noted in only three eyes of two PRK patients. Conclusion LE gel appears to have a high level of safety and tolerability when used for the management of postoperative pain and inflammation following LASIK

INTACS before or after laser in situ keratomileusis: correction of thin corneas with moderately high myopia.

PubMed

Ito, Mitsutoshi; Arai, Hiroyuki; Fukumoto, Teruki; Toda, Ikuko; Tsubota, Kazuo

2004-01-01

Intrastromal corneal ring segments (INTACS Micro-Thin Prescription Inserts by Addition Technologies, Fremont, Calif) were inserted as a combined surgery with laser in situ keratomileusis (LASIK) in six eyes with thin corneas to correct moderately high myopia. INTACS were implanted before LASIK (INTACS-LASIK) in three eyes and after LASIK (LASIK-INTACS) in three eyes. Mean preoperative manifest spherical equivalent refraction was -7.88 diopters. Mean follow-up was 306 days. No intraoperative complications occurred. The LASIK-INTACS eyes were slightly more overcorrected than the INTACS-LASIK eyes because of the enhanced performance of INTACS in the thinned corneal tissue. Induced astigmatism by INTACS per se was less in the LASIK-INTACS eyes than in the INTACS-LASIK eyes. At last examination, uncorrected visual acuity was better than 20/25 in all eyes. Best spectacle-corrected visual acuity was within 1 line of the preoperative value in all eyes. Both methods resulted in significant improvement in visual acuity and refraction. Based on our limited experience, however, LASIK followed by INTACS is preferred for reasons of safety, convenience, and lower induced cylinder.

Lamina Cribrosa Changes after Laser In Situ Keratomileusis in Myopic Eyes

PubMed Central

Lee, Soomin; Choi, Da-Ye Diana; Lim, Dong Hui; Chung, Tae Young; Han, Jong Chul

2018-01-01

Purpose To determine deep optic nerve head structure changes after transient intraocular pressure elevation during laser in situ keratomileusis (LASIK) for myopia. Methods Enhanced depth imaging-optical coherence tomography was performed in each myopic eye that underwent LASIK surgery. Enhanced depth imaging-optical coherence tomography images were created at postoperative 1 day, 1 week, 2 weeks, and 1 month. Lamina cribrosa (LC) thickness, LC depth and prelaminar thickness at the superior, middle and inferior portions of the optic nerve head were measured by two investigators. Results Forty eyes in 40 patients were included in the present study. During follow-up, there were no significant differences in prelaminar thickness or LC depth. The LC demonstrated increased thickness at postoperative 1 day at all three locations (superior, middle, and inferior) (p < 0.001, p < 0.001, p < 0.001, respectively). However, no significant changes were observed at postoperative 1 week, 2 weeks, and 1 month. Conclusions The LC thickness could increase at 1 day after LASIK surgery. However, the thickness will gradually return to baseline morphology. Temporary intraocular pressure increase during LASIK does not appear to induce irreversible LC thickness changes. PMID:29611373

Lamina Cribrosa Changes after Laser In Situ Keratomileusis in Myopic Eyes.

PubMed

Lee, Soomin; Choi, Da Ye Diana; Lim, Dong Hui; Chung, Tae Young; Han, Jong Chul; Kee, Changwon

2018-04-01

To determine deep optic nerve head structure changes after transient intraocular pressure elevation during laser in situ keratomileusis (LASIK) for myopia. Enhanced depth imaging-optical coherence tomography was performed in each myopic eye that underwent LASIK surgery. Enhanced depth imaging-optical coherence tomography images were created at postoperative 1 day, 1 week, 2 weeks, and 1 month. Lamina cribrosa (LC) thickness, LC depth and prelaminar thickness at the superior, middle and inferior portions of the optic nerve head were measured by two investigators. Forty eyes in 40 patients were included in the present study. During follow-up, there were no significant differences in prelaminar thickness or LC depth. The LC demonstrated increased thickness at postoperative 1 day at all three locations (superior, middle, and inferior) (p < 0.001, p < 0.001, p < 0.001, respectively). However, no significant changes were observed at postoperative 1 week, 2 weeks, and 1 month. The LC thickness could increase at 1 day after LASIK surgery. However, the thickness will gradually return to baseline morphology. Temporary intraocular pressure increase during LASIK does not appear to induce irreversible LC thickness changes. © 2018 The Korean Ophthalmological Society.

Seven-year changes in corneal power and aberrations after PRK or LASIK.

PubMed

Ivarsen, Anders; Hjortdal, Jesper

2012-09-06

To examine long-term changes in corneal power and aberrations in myopic patients randomized to photorefractive keratectomy (PRK) or laser in situ keratomileusis (LASIK). Forty-five patients with myopia from -6 to -8 diopters (spherical equivalent refraction) were randomized to PRK (n = 20) or LASIK (n = 25). Patients were examined preoperatively and for up to 7 years after surgery. Measurements included refraction, topography (TMS-1), and ultrasound pachymetry. By 3 years, 16 PRK and 15 LASIK patients were examined and by 7 years, 9 PRK and 7 LASIK subjects were available. Only patients who had not been reoperated and attended the two late controls were included in data analyses. Optical analysis of topographic data was used to calculate corneal power and wavefront aberrations. PRK and LASIK caused a similar reduction in corneal power. During the first year after PRK, corneal power increased, but remained stable from 1 to 7 years. In contrast, corneal power continued to increase from 1 to 7 years after LASIK. Both PRK and LASIK caused an increase in coma-like and spherical aberrations that remained constant for 7 years. No significant changes in other higher-order aberrations were observed. The cornea may not be stable even 7 years after LASIK, as indicated by the continuing increase in corneal power. In contrast, PRK appears stable from 1 year post surgery. Coma-like and spherical aberrations are permanently increased after PRK and LASIK. (ClinicalTrials.gov number, NCT00404105.).

Optical Quality, Threshold Target Identification, and Military Target Task Performance After Advanced Keratorefractive Surgery

DTIC Science & Technology

2012-05-01

undergo wavefront-guided (WFG) photorefractive keratectomy ( PRK ), WFG laser in situ keratomileusis ( LASIK ), wavefront optimized (WFO) PRK or WFO...Military, Refractive Surgery, PRK , LASIK , Night Vision, Wavefront Optimized, Wavefront Guided, Visual Performance, Quality of Vision, Outcomes...military. In a prospective, randomized treatment trial we will enroll 224 nearsighted soldiers to WFG photorefractive keratectomy ( PRK ), WFG LASIK , WFO PRK

Laser-assisted subepithelial keratectomy (LASEK) versus laser-assisted in-situ keratomileusis (LASIK) for correcting myopia

PubMed Central

Kuryan, Jocelyn; Cheema, Anjum; Chuck, Roy S

2017-01-01

Background Near-sightedness, or myopia, is a condition in which light rays entering the eye along the visual axis focus in front of the retina, resulting in blurred vision. Myopia can be treated with spectacles, contact lenses, or refractive surgery. Options for refractive surgery include laser-assisted subepithelial keratectomy (LASEK) and laser-assisted in-situ keratomileusis (LASIK). Both procedures utilize a laser to shape the corneal tissue (front of the eye) to correct refractive error, and both create flaps before laser treatment of corneal stromal tissue. Whereas the flap in LASEK is more superficial and epithelial, in LASIK it is thicker and also includes some anterior stromal tissue. LASEK is considered a surface ablation procedure, much like its predecessor, photorefractive keratectomy (PRK). LASEK was developed as an alternative to PRK to address the issue of pain associated with epithelial debridement used for PRK. Assessing the relative benefits and risks/side effects of LASEK and LASIK warrants a systematic review. Objectives To assess the effects of LASEK versus LASIK for correcting myopia. Search methods We searched the Cochrane Central Register of Controlled Trials (CENTRAL), which contains the Cochrane Eyes and Vision Trials Register (2016, Issue 10); MEDLINE Ovid (1946 to 24 October 2016); Embase.com (1947 to 24 October 2016); PubMed (1948 to 24 October 2016); LILACS (Latin American and Caribbean Health Sciences Literature Database; 1982 to 24 October 2016); the metaRegister of Controlled Trials (mRCT) (www.controlled-trials.com), last searched 20 June 2014; ClinicalTrials.gov (www.clinicaltrials.gov); searched 24 October 2016; and the WHO International Clinical Trials Registry Platform (ICTRP) (www.who.int/ictrp/search/en); searched 24 October 2016. We did not use any date or language restrictions in the electronic searches for trials. Selection criteria We considered only randomized controlled trials (RCTs) for the purposes of this review

Optical Quality and Threshold Target Identification and Military Target Task Performance after Advanced Keratorefractive Surgery

DTIC Science & Technology

2013-05-01

and Sensors Directorate. • Study participants and physicians select treatment: PRK or LASIK . WFG vs . WFO treatment modality is randomized. The...to undergo wavefront-guided (WFG) photorefractive keratectomy ( PRK ), WFG laser in situ keratomileusis ( LASIK ), wavefront optimized (WFO) PRK or WFO...TERMS Military, Refractive Surgery, PRK , LASIK , Night Vision, Wavefront Optimized, Wavefront Guided, Visual Performance, Quality of Vision, Outcomes

Management of the ocular surface and tear film before, during, and after laser in situ keratomileusis.

PubMed

Albietz, Julie M; Lenton, Lee M

2004-01-01

To identify evidence-based, best practice strategies for managing the ocular surface and tear film before, during, and after laser in situ keratomileusis (LASIK). After a comprehensive review of relevant published literature, evidence-based recommendations for best practice management strategies are presented. Symptoms of ocular irritation and signs of dysfunction of the integrated lacrimal gland/ocular surface functional gland unit are common before and after LASIK. The status of the ocular surface and tear film before LASIK can impact surgical outcomes in terms of potential complications during and after surgery, refractive outcome, optical quality, patient satisfaction, and the severity and duration of dry eye after LASIK. Before LASIK, the health of the ocular surface should be optimized and patients selected appropriately. Dry eye before surgery and female gender are risk factors for developing chronic dry eye after LASIK. Management of the ocular surface during LASIK can minimize ocular surface damage and the risk of adverse outcomes. Long-term management of the tear film and ocular surface after LASIK can reduce the severity and duration of dry eye symptoms and signs. Strategies to manage the integrated ocular surface/lacrimal gland functional unit before, during, and after LASIK can optimize outcomes. As problems with the ocular surface and tear film are relatively common, attention should focus on the use and improvement of evidence-based management strategies.

LASIK

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... of this Web site is to provide objective information to the public about LASIK surgery. See other ... undergoing LASIK surgery. This web site also provides information on FDA’s role in LASIK surgery, FDA’s current ...

Is LASIK for Me? A Patient's Guide to Refractive Surgery

MedlinePlus

... whether LASIK would be appropriate for you are: • dry eye syndrome . If dry eye is left untreated prior to surgery, patients may be disappointed with their LASIK results. If dry eye is diagnosed and adequately treated before surgery, you ...

Comparison of visual acuity of the patients on the first day after sub-Bowman keratomileusis or laser in situ keratomileusis

PubMed Central

Zhao, Wei; Wu, Ting; Dong, Ze-Hong; Feng, Jie; Ren, Yu-Feng; Wang, Yu-Sheng

2016-01-01

AIM To compare recovery of the visual acuity in patients one day after sub-Bowman keratomileusis (SBK) or laser in situ keratomileusis (LASIK). METHODS Data from 5923 eyes in 2968 patients that received LASIK (2755 eyes) or SBK (3168 eyes) were retrospectively analyzed. The eyes were divided into 4 groups according to preoperative spherical equivalent: between -12.00 to -9.00 D, extremely high myopia (n=396, including 192 and 204 in SBK and LASIK groups, respectively); -9.00 to -6.00 D, high myopia (n=1822, including 991 and 831 in SBK and LASIK groups, respectively), -6.00 to -3.00 D, moderate myopia (n=3071, including 1658 and 1413 in SBK and LASIK groups, respectively), and -3.00 to 0.00 D, low myopia (n=634, including 327 and 307 in SBK and LASIK groups, respectively). Uncorrected logMAR visual acuity values of patients were assessed under standard natural light. Analysis of variance was used for comparisons among different groups. RESULTS Uncorrected visual acuity values were 0.0115±0.1051 and 0.0466±0.1477 at day 1 after operation for patients receiving SBK and LASIK, respectively (P<0.01); visual acuity values of 0.1854±0.1842, 0.0615±0.1326, -0.0033±0.0978, and -0.0164±0.0972 were obtained for patients in the extremely high, high, moderate, and low myopia groups, respectively (P<0.01). In addition, significant differences in visual acuity at day 1 after operation were found between patients receiving SBK and LASIK in each myopia subgroup. CONCLUSION Compared with LASIK, SBK is safer and more effective, with faster recovery. Therefore, SBK is more likely to be accepted by patients than LASIK for better uncorrected visual acuity the day following operation. PMID:27158619

Comparison of visual acuity of the patients on the first day after sub-Bowman keratomileusis or laser in situ keratomileusis.

PubMed

Zhao, Wei; Wu, Ting; Dong, Ze-Hong; Feng, Jie; Ren, Yu-Feng; Wang, Yu-Sheng

2016-01-01

To compare recovery of the visual acuity in patients one day after sub-Bowman keratomileusis (SBK) or laser in situ keratomileusis (LASIK). Data from 5923 eyes in 2968 patients that received LASIK (2755 eyes) or SBK (3168 eyes) were retrospectively analyzed. The eyes were divided into 4 groups according to preoperative spherical equivalent: between -12.00 to -9.00 D, extremely high myopia (n=396, including 192 and 204 in SBK and LASIK groups, respectively); -9.00 to -6.00 D, high myopia (n=1822, including 991 and 831 in SBK and LASIK groups, respectively), -6.00 to -3.00 D, moderate myopia (n=3071, including 1658 and 1413 in SBK and LASIK groups, respectively), and -3.00 to 0.00 D, low myopia (n=634, including 327 and 307 in SBK and LASIK groups, respectively). Uncorrected logMAR visual acuity values of patients were assessed under standard natural light. Analysis of variance was used for comparisons among different groups. Uncorrected visual acuity values were 0.0115±0.1051 and 0.0466±0.1477 at day 1 after operation for patients receiving SBK and LASIK, respectively (P<0.01); visual acuity values of 0.1854±0.1842, 0.0615±0.1326, -0.0033±0.0978, and -0.0164±0.0972 were obtained for patients in the extremely high, high, moderate, and low myopia groups, respectively (P<0.01). In addition, significant differences in visual acuity at day 1 after operation were found between patients receiving SBK and LASIK in each myopia subgroup. Compared with LASIK, SBK is safer and more effective, with faster recovery. Therefore, SBK is more likely to be accepted by patients than LASIK for better uncorrected visual acuity the day following operation.

Dry eye after laser in-situ keratomileusis.

PubMed

Raoof, Duna; Pineda, Roberto

2014-01-01

Laser-assisted in-situ keratomileusis (LASIK) is one of the most commonly performed refractive procedures with excellent visual outcomes. Dry eye syndrome is one of the most frequently seen complications after LASIK, with most patients developing at least some mild dry eye symptoms postoperatively. To achieve improved visual outcomes and greater patient satisfaction, it is essential to identify patients prone to dry eyes preoperatively, and initiate treatment early in the course. Enhanced understanding of the pathophysiology of post-LASIK dry eye will help advance our approach to its management.

Levels of the Novel Glycoprotein Lacritin in Human Tears After Laser Refractive Surgery

DTIC Science & Technology

2012-10-01

and HPSE before and after surgery as well as comparison of responses between procedures ( PRK vs . LASIK ). The primary outcome measure is tear lacritin...patients undergoing PRK (photorefractive keratectomy) and LASIK (Laser-assisted in situ keratomileusis) with the possibility of the development of...recombinant lacritin as a novel therapeutic agent for wound healing. Up to 196 patients eligible to undergo PRK or LASIK at the U.S. Army Warfighter

Iris registration in wavefront-guided LASIK to correct mixed astigmatism.

PubMed

Khalifa, Mounir; El-Kateb, Mohamed; Shaheen, Mohamed Shafik

2009-03-01

To investigate the predictability, safety, and efficiency of wavefront-guided laser in situ keratomileusis (LASIK) with iris-registration technology to correct mixed astigmatism. Vision correction center, Alexandria, Egypt. This retrospective double-blind study included randomly selected patients with mixed astigmatism who sought laser refractive surgery. Patients were divided equally into 3 groups and treated with conventional LASIK and manual marking, wavefront-guided LASIK and manual marking, or wavefront-guided LASIK with iris registration (LASIK+IR group). Eyes were analyzed preoperatively and up to 3 months postoperatively. The LASIK+IR group had better postoperative uncorrected visual acuity (100% 20/30 or better; 90% 20/20 or better; 20% 20/16 or better) than the other groups and did not lose preoperative best spectacle-corrected visual acuity, unlike the other groups. This group also had the highest percentage of eyes that gained lines of acuity (20% 1 line; 10% 2 lines). The LASIK+IR group had the highest predictability of spherical refraction (80% within +/-0.50 diopter [D]; 100% within +/-1.00 D [P<.05] and the highest predictability of cylinder refraction. The LASIK+IR eyes had a significantly smaller increase postoperatively in coma, trefoil, and secondary astigmatism. There was no significant difference between groups in spherical aberration or quadrafoil. The LASIK-IR group had the most improvement in scotopic contrast sensitivity (P<.05). Wavefront-guided LASIK with iris registration was more predictable, safe, and efficient than conventional or wavefront-guided LASIK with manual marking in correcting mixed astigmatism. Further studies are needed to confirm these results.

Laser in situ keratomileusis in 2012: a review.

PubMed

Sutton, Gerard; Lawless, Michael; Hodge, Christopher

2014-01-01

Laser in situ keratomileusis (LASIK) is a safe and effective treatment for refractive error. A combination of technological advances and increasing surgeon experience has served to further refine refractive outcomes and reduce complication rates. In this article, we review LASIK as it stands in late 2012: the procedure, indications, technology, complications and refractive outcomes. © 2013 The Authors. Clinical and Experimental Optometry © 2013 Optometrists Association Australia.

Posterior corneal topographic changes after partial flap during laser in situ keratomileusis

PubMed Central

Sharma, N; Rani, A; Balasubramanya, R; Vajpayee, R B; Pandey, R M

2003-01-01

Aim: To study the posterior corneal topographic changes in eyes with partial flaps during laser assisted in situ keratomileusis (LASIK). Methods: Case records of 16 patients, who had partial flap in one eye during LASIK (group 1) and uncomplicated surgery in the other eye (group 2), were studied. Following occurrence of partial flap intraoperatively, laser ablation was abandoned in all the eyes. A 160/180 μm flap was attempted during the initial procedure using the Hansatome microkeratome (Bausch & Lomb Surgicals, Munich, Germany). LASIK surgery in all cases was performed using a 180 μm plate, at the mean interval of 4.16 (SD 1.5) months following the initial procedure. None of the eyes had intraoperative complication during LASIK. Relative posterior corneal surface elevation above the best fit sphere (BFS) before the initial procedure, before, and after LASIK were compared using the Orbscan slit scanning corneal topography/pachymetry system. Results: Posterior corneal elevation was comparable in the two groups, both preoperatively (group 1; 16.4 (4.8) μm, group 2; 16.1 (4.8) μm) and after final surgery (group 1; 57.2 (15.6) μm, group 2; 54.3 (13.1) μm). In group 1 after occurrence of partial flap, the posterior corneal elevation was 16.9 (4.4) μm, and this increase was not significant statistically (p=0.4). On multiple linear regression analysis, residual bed thickness (p<0.001) was independently the significant determinant of final posterior corneal elevation in both groups. Conclusion: The inadvertent occurrence of partial flap during LASIK procedure does not contribute to the increase in posterior corneal elevation. PMID:12543743

Accelerated corneal crosslinking concurrent with laser in situ keratomileusis.

PubMed

Celik, H Ugur; Alagöz, Nese; Yildirim, Yusuf; Agca, Alper; Marshall, John; Demirok, Ahmet; Yilmaz, Omer Faruk

2012-08-01

To assess accelerated corneal collagen crosslinking (CXL) applied concurrently with laser in situ keratomileusis (LASIK) in a small group of patients. Beyoglu Eye Research and Training Hospital, Istanbul, Turkey. Prospective pilot interventional case series. In May 2010, patients had LASIK with concurrent accelerated CXL in 1 eye and LASIK only in the fellow eye to treat myopia or myopic astigmatism. The follow-up was 12 months. The attempted correction (spherical equivalent) ranged from -5.00 to -8.50 diopters (D) in the LASIK-CXL group and from -3.00 to -7.25 D in the LASIK-only group. Main outcome measures were manifest refraction, uncorrected (UDVA) and corrected (CDVA) distance visual acuities, and the endothelial cell count. Eight eyes of 3 women and 1 man (age 22 to 39 years old) were enrolled. At the 12-month follow-up, the LASIK-CXL group had a UDVA and manifest refraction equal to or better than those in the LASIK-only group. No eye lost 1 or more lines of CDVA at the final visit. The endothelial cell loss in the LASIK-CXL eye was not greater than in the fellow eye. No side effects were associated with either procedure. Laser in situ keratomileusis with accelerated CXL appears to be a promising modality for future applications to prevent corneal ectasia after LASIK treatment. The results in this pilot series suggest that evaluation of a larger study cohort is warranted. Drs. Yilmaz and Marshall are paid consultants to Avedro, Inc. No other author has a financial or proprietary interest in any material or method mentioned. Copyright © 2012 ASCRS and ESCRS. Published by Elsevier Inc. All rights reserved.

Laser Refractive Surgery

NASA Astrophysics Data System (ADS)

Wynne, James

Refractive surgery has its roots in corneal transplant surgery, first performed in 1905, where the damaged or diseased cornea of a living individual is replaced by donated corneal tissue taken from a recently deceased individual. Since the cornea has no blood supply, there is no danger of organ rejection. Recognizing the exceptional healing power of corneal tissue, ophthalmologists began to explore methods of reshaping the cornea to improve the visual acuity of patients suffering from myopia, hyperopia, and astigmatism. In 1964, a procedure known as keratomileusis was introduced. In 1974, radial keratotomy (RK) was introduced. In 1981, excimer laser surgery was discovered by the speaker and his IBM Research colleagues. In 1983, the excimer laser was used to create clean, precise incisions in the cornea of enucleated calf eyes, derived from slaughter, launching the era of laser refractive surgery, with more precise and safer techniques to correct myopia, hyperopia, and stigmatism. This talk will describe the widely practiced surgical procedures known as photorefractive keratectomy (PRK) and laser-assisted in situ keratomileusis (LASIK), which have improved the visual acuity of more than 35 million people. Most patients undergoing PRK or LASIK end up with uncorrected vision better than 20/20. In 2007, development commenced on a new procedure known as small incision lenticule extraction (SMILE), employing a femtosecond laser and no excimer laser. SMILE is promoted as minimally invasive and combining the advantages of PRK and LASIK. However, long term stability of visual acuity following SMILE surgery is yet to be determined.

Fundus oculi pigmentation studies simulating the fs-LASIK process Fundus oculi pigmentation studies simulating the fs-LASIK process

NASA Astrophysics Data System (ADS)

Sander, M.; Minet, O.; Zabarylo, U.; Müller, M.; Tetz, M. R.

2012-06-01

The femtosecond-laser in situ keratomileusis (fs-LASIK) technique has successfully entered the refractive surgery market to correct ametropia by cutting transparent corneal tissue with ultra-short laser pulses based on photodisruption. The laser pulses in the near infrared range (NIR) generate a laser-induced breakdown (LIOB) in the cornea. By propagating through the eye, a certain amount of the pulse is deposited in the cornea and the remaining energy interacts with the strong absorbing tissue behind. Due to the absorption by the retinal pigment epithelium and the transfer of the thermal energy to surrounding tissue, the transmitted energy can induce damage to the retina. The aim of this project was to find out the threshold influences concerning the tissue and the correlation between the results of the macroscopical appraisal and the fundus oculi pigmentation by simulating the fs-LASIK procedure with two various laser systems in the continuous wave (CW) and fs-regime. Therefore ex-vivo determinations were carried out macroscopically and histopathologically on porcine tissue.

Effect of Laser in Situ Keratomileusis on Schiøtz, Goldmann, and Dynamic Contour Tonometric Measurements.

PubMed

Sales-Sanz, Marco; Arranz-Marquez, Esther; Piñero, David P; Arruabarrena, Carolina; Mikropoulos, Dimitrios G; Teus, Miguel A

2016-04-01

To assess the effect of laser in situ keratomileusis (LASIK) on ocular rigidity and compare its effect on intraocular pressure (IOP) readings with Goldmann applanation tonometry (GAT), Schiøtz indentation tonometry (ST), and dynamic contour tonometry (DCT). Prospective, observational, single-masked study. Eighty-one patients who underwent myopic LASIK and 108 unoperated myopic control patients were included in the study. The IOP was measured using GAT, DCT, and ST. The coefficient of ocular rigidity (Ko) was obtained from the regression analysis of the 3 readings obtained with each weight of the ST. Linear multiple regression analysis was performed with dummy variables to assess the effects of age, central corneal thickness (CCT), and refractive surgery on measured IOP values. Age, CCT, and previous LASIK explained 39.41% of the IOP readings with GAT, 25.31% with DCT, and 3.28% with ST. LASIK caused a mean decrease of -2.51 mm Hg in IOP readings (P=0.000) with GAT, -1.29 mm Hg (P=0.036) with DCT, and no significant change in IOP readings with ST (P=0.299). Significant differences in the Ko were observed between the LASIK and control groups. The Ko values were unrelated to age and CCT in the LASIK and control groups. ST seems to be less affected by previous LASIK procedures. There is a difference in the ocular rigidity between the unoperated and LASIK eyes that is not correlated with the CCT. Therefore, ST seems to measure changes in the biomechanical behavior of corneas that underwent LASIK surgery.

Overview of refractive surgery.

PubMed

Bower, K S; Weichel, E D; Kim, T J

2001-10-01

Patients with myopia, hyperopia and astigmatism can now reduce or eliminate their dependence on contact lenses and eyeglasses through refractive surgery that includes radial keratotomy (RK), photorefractive keratectomy (PRK), laser-assisted in situ keratomileusis (LASIK), laser thermal keratoplasty (LTK) and intrastromal corneal rings (ICR). Since the approval of the excimer laser in 1995, the popularity of RK has declined because of the superior outcomes from PRK and LASIK. In patients with low-to-moderate myopia, PRK produces stable and predictable results with an excellent safety profile. LASIK is also efficacious, predictable and safe, with the additional advantages of rapid vision recovery and minimal pain. LASIK has rapidly become the most widely performed refractive surgery, with high patient and surgeon satisfaction. Noncontact Holium: YAG LTK provides satisfactory correction in patients with low hyperopia. ICR offers patients with low myopia the potential advantage of removal if the vision outcome is unsatisfactory. Despite the current widespread advertising and media attention about laser refractive surgery, not all patients are good candidates for this surgery. Family physicians should be familiar with the different refractive surgeries and their potential complications.

Late-onset traumatic dislocation of laser in situ keratomileusis corneal flaps: a case series with many clinical lessons.

PubMed

Ting, Darren Shu Jeng; Danjoux, Jean-Pierre

2018-05-12

To report three cases of late-onset (7-14 years postoperative) traumatic dislocation of laser in situ keratomileusis (LASIK) flaps with epithelial ingrowth that all had delayed surgical intervention. A retrospective, interventional case series of three patients who underwent flap repositioning and mechanical debridement of epithelial ingrowth, all after an initial delayed diagnosis/treatment of dislocated LASIK flap. Visual improvement was noted in all three cases following LASIK flap repositioning and debridement of epithelial ingrowth; patient 1 improved from 20/800 corrected-distance-visual-acuity (CDVA) to 20/20 uncorrected-distance-visual-acuity (UDVA) postoperative (14 years post-LASIK, 5-week interval between injury and surgery), patient 2 improved from 20/50 CDVA to 20/20 CDVA (10 years post-LASIK, 4-month interval between injury and surgery) and patient 3 improved from 20/80 CDVA to 20/60 CDVA (7 years post-LASIK, 14-month interval between injury and surgery). Flap dislocation was not suspected or diagnosed in two patients during the first ophthalmic visit. Postoperative visual outcome was not influenced by the presenting vision but might be negatively affected by the delay in surgical intervention, the presence of preoperative central epithelial ingrowth and postoperative striae. This case series reported one of the longest documented intervals between LASIK and traumatic dislocation of LASIK flap with secondary epithelial ingrowth. Delayed diagnosis and management of flap dislocation after corneal trauma may potentially increase the risk of epithelial ingrowth, recalcitrant flap striae and visual impairment. The presence of late-onset epithelial ingrowth in patients with previous LASIK mandates careful examination for occult flap displacement.

Recent advances in laser in situ keratomileusis-associated dry eye.

PubMed

Xie, Wenjia

2016-03-01

Dry eye is the most common complication after laser in situ keratomileusis (LASIK). The major cause of LASIK-associated dry eye is corneal nerve damage. Early identification and treatment of post-operative dry eye are essential to prevent further ocular surface damage. This article reviews the recent studies of LASIK-associated dry eye, including clinical features, aetiology, risk factors, evaluations and treatment. The applications of novel technologies in LASIK-associated dry eye evaluation like anterior segment spectral-domain optical coherence tomography (SD-OCT) and corneal confocal microscopy are also introduced in this review. © 2016 Optometry Australia.

Diplopia after laser in situ keratomileusis (LASIK) in a patient with a history of strabismus.

PubMed

Heinmiller, Laura J; Wasserman, Barry N

2013-02-01

In patients with a history of strabismus, refractive surgery can result in decompensation of ocular alignment, with subsequent diplopia. Refractive surgery in the management of strabismus has been described, although it remains controversial. We present a young adult with past history of strabismus surgery and new-onset diplopia after refractive surgery. Binocular diplopia was treated surgically with laser in situ keratomileusis. Copyright © 2013 American Association for Pediatric Ophthalmology and Strabismus. Published by Mosby, Inc. All rights reserved.

Higher-order aberrations after wavefront-optimized photorefractive keratectomy and laser in situ keratomileusis

PubMed Central

Randleman, J. Bradley; Perez-Straziota, Claudia E.; Hu, Michelle H.; White, Alfred J.; Loft, Evan S.; Stulting, R. Doyle

2013-01-01

PURPOSE To analyze the changes in higher-order aberrations (HOAs) that occur after wavefront-optimized photorefractive keratectomy (PRK) and laser in situ keratomileusis (LASIK). SETTING Private practice, Atlanta, Georgia, USA. METHODS This retrospective analysis comprised eyes that had PRK or LASIK from June 2004 through October 2005. Postoperative outcome measures included 3-month uncorrected visual acuity (UCVA), best spectacle-corrected visual acuity (BSCVA), manifest refraction spherical equivalent (MRSE), changes in the root mean square (RMS) and grouped coefficient HOAs (microns) measured with a corneal analyzer, and subjective assessment of visual aberrations. RESULTS One hundred consecutive eyes of 54 patients had PRK, and 100 contemporaneous consecutive eyes of 71 patients had LASIK. The PRK and LASIK populations were similar in general demographics, preoperative HOAs, and postoperative UCVA and BSCVA. The mean MRSE was slightly hyperopic after PRK (mean +0.11 diopters [D]) and slightly myopic after LASIK (mean −0.19 D) (P<.0001). There were no statistically significant changes in RMS or grouped coefficient HOA values after PRK or LASIK, nor were there significant differences in postoperative RMS or grouped coefficient HOA values between PRK and LASIK. One percent of PRK and LASIK patients reported a subjective increase in postoperative visual aberrations; 5% reported a subjective improvement postoperatively. CONCLUSIONS Wavefront-optimized excimer laser surgery did not induce significant HOAs after PRK or LASIK. The 2 techniques were equally efficacious and had equivalent postoperative HOA profiles. PMID:19185240

[Advantages and disadvantages of femtosecond laser assisted LASIK and SMILE].

PubMed

Zhang, F J; Sun, M S

2018-01-11

With the development of excimer laser and femtosecond laser equipment, application of diversified and customized surgical decision in modern corneal refractive surgery has been an inevitable trend. However, how to make a personalized decision with an accurate surgical design to achieve better visual quality becomes the main focus in clinical applications. Small-incision lenticule extraction (SMILE) and femtosecond assisted laser in situ keratomileusis (FS-LASIK) have been commonly acknowledged as the mainstream of corneal refractive surgery for ametropia correction nowadays. Both methods have been verified by clinical practice for many years. This article compares and elaborates the different characteristics with advantages and disadvantages of the two methods so as to provide some reasonable treatment options for refractive surgery. (Chin J Ophthalmol, 2018, 54: 7-10) .

Visual and flight performance recovery after PRK or LASIK in helicopter pilots.

PubMed

Van de Pol, Corina; Greig, Joanna L; Estrada, Art; Bissette, Gina M; Bower, Kraig S

2007-06-01

Refractive surgery, specifically photorefractive keratectomy (PRK) and laser in situ keratomileusis (LASIK), is becoming more accepted in the military environment. Determination of the impact on visual performance in the more demanding aviation environment was the impetus for this study. A prospective evaluation of 20 Black Hawk pilots pre-surgically and at 1 wk, 1 mo, and 6 mo postsurgery was conducted to assess both PRK and LASIK visual and flight performance outcomes on the return of aviators to duty. Of 20 pilots, 19 returned to flight status at 1 mo after surgery; 1 PRK subject was delayed due to corneal haze and subjective visual symptoms. Improvements were seen under simulator night and night vision goggle flight after LASIK; no significant changes in flight performance were measured in the aircraft. Results indicated a significantly faster recovery of all visual performance outcomes 1 wk after LASIK vs. PRK, with no difference between procedures at 1 and 6 mo. Low contrast acuity and contrast sensitivity only weakly correlated to flight performance in the early post-operative period. Overall flight performance assessed in this study after PRK and LASIK was stable or improved from baseline, indicating a resilience of performance despite measured decrements in visual performance, especially in PRK. More visually demanding flight tasks may be impacted by subtle changes in visual performance. Contrast tests are more sensitive to the effects of refractive surgical intervention and may prove to be a better indicator of visual recovery for return to flight status.

Assessment of refractive outcome of femtosecond-assisted LASIK for hyperopia correction

PubMed Central

El-Naggar, Mohamed Tarek; Hovaghimian, Dikran Gilbert

2017-01-01

Introduction Laser vision correction for hyperopia is challenging. The purpose of the study was to assess the refractive outcomes of femtosecond-assisted laser in situ keratomileusis (LASIK) for hyperopic correction using wavefront-optimized ablation profiles. Methods This retrospective case series study included 20 Egyptian patients (40 eyes) with hyperopia or hyperopic astigmatism with a mean manifest refraction spherical equivalent (MRSE) of +2.55D±1.17 (range from +1.00 to +6.00) who had uneventful femtosecond-a assisted LASIK with wavefront-optimized aspheric ablation profile using refractive surgery suite (WaveLight FS200 Femtosecond Laser and WaveLight EX500 Excimer Laser) performed in the Research Institute of Ophthalmology and International Eye Hospital, Giza, Egypt. Statistical analysis was done using Microsoft Excel (Microsoft Corporation, Seattle, WA, USA). Results The procedure significantly reduced the MRSE and cylinder post-operatively (95% were ± 0.50D and 100% ± 1.00 D), with stability of refraction and UDVA over the follow-up period (up to 12 months) after surgery. No eye lost any line of the CDVA, which reflects the excellent safety profile of the procedure; on the other hand, one eye (5%) gained one line and one eye (5%) even gained two lines. There were no significant complications during the procedure. Conclusions Femtosecond-assisted laser in situ keratomileusis for hyperopia showed predictable, effective, and safe refractive outcomes that were stable through 12 months. Longer follow-up period is required to detect any further regression PMID:28461870

The effect of flap thickness on corneal biomechanics after myopic laser in situ keratomileusis using the M-2 microkeratome.

PubMed

Goussous, Iyad A; El-Agha, Mohamed-Sameh; Awadein, Ahmed; Hosny, Mohamed H; Ghaith, Alaa A; Khattab, Ahmed L

2017-01-01

The purpose of this study was to determine the effect of flap thickness on corneal biomechanics after myopic laser in situ keratomileusis (LASIK). This is a prospective controlled non-randomized, institutional study. Patients underwent either epi-LASIK with mitomycin (advanced surface ablation [ASA]), thin-flap LASIK (90 µm head), or thick-flap LASIK (130 µm head). In ASA, the Moria Epi-K hydroseparator was used. LASIK flaps were created using the Moria M-2 mechanical microkeratome. The corneal hysteresis (CH) and corneal resistance factor (CRF) were measured preoperatively and 3 months after surgery, using the Ocular Response Analyzer ® . Ten patients (19 eyes) underwent ASA, 11 patients (16 eyes) underwent thin-flap LASIK, and 11 patients (16 eyes) underwent thick-flap LASIK. The mean preoperative CH was 10.47±0.88, 10.52±1.4, and 11.28±1.4 mmHg ( p =0.043), respectively, decreasing after surgery by 1.75±1.02, 1.66±1.00, and 2.62±1.03 mmHg ( p =0.017). The mean reduction of CH per micron of central corneal ablation was 0.031, 0.023, and 0.049 mmHg/µm ( p =0.005). Mean preoperative CRF was 10.11±1.28, 10.34±1.87, and 10.62±1.76 mmHg ( p =0.66), decreasing after surgery by 2.33±1.35, 2.77±1.03, and 2.92±1.10 mmHg ( p =0.308). The mean reduction of CRF per micron of central corneal ablation was 0.039, 0.040, and 0.051 mmHg/µm ( p =0.112). Thick-flap LASIK caused a greater reduction of CH and CRF than thin-flap LASIK and ASA, although this was statistically significant only for CH. ASA and thin-flap LASIK were found to be biomechanically similar.

[Scattered light and glare sensitivity after wavefront-guided photorefractive keratectomy (WFG-PRK) and laser in situ keratomileusis (WFG-LASIK)].

PubMed

Vignal, R; Tanzer, D; Brunstetter, T; Schallhorn, S

2008-05-01

To compare glare sensitivity measured by the intraocular scattered light between WFG-PRK and WFG-LASIK at 12 months follow-up and to assess its correlation to patients' complaints. Prospective and randomized study on 13 patients treated with WFG-LASIK, 13 patients with WFG-PRK and a control group of 35 patients. The intraocular stray light was measured by the Oculus C-Quant 12 months after surgery and before surgery for the control group. Photopic and mesopic contrast acuity and glare symptoms were reported pre- and postoperatively. Stray light values were normal in 79% of patients after WFG-LASIK and PRK and 86% in the control group, with mean values of 1.05 log, 1.03 log, and 0.99 log, respectively (p>0.05). All the patients with significant glare complaints had impaired stray light values versus 31.5% in the no-complaint group. Photopic and mesopic contrast acuity and glare symptoms were improved 1 year after surgery compared to preoperatively (no significant difference between groups). WFG-LASIK and PRK are safe and equivalent procedures regarding quality of vision. The measurement of stray light can be a discriminative test to assessing patients' glare complaints.

One-year outcomes of a bilateral randomised prospective clinical trial comparing PRK with mitomycin C and LASIK.

PubMed

Wallau, A D; Campos, M

2009-12-01

To compare 1-year follow-up results of photorefractive keratectomy (PRK) with mitomycin C (MMC) and laser in situ keratomileusis (LASIK) for custom correction of myopia. Eighty-eight eyes of 44 patients with moderate myopia were randomised to PRK with 0.002% MMC for 1 min in one eye and LASIK in the fellow eye. The 1-year follow-up was evaluated. There were no differences between LASIK and MMC-PRK eyes preoperatively. Forty-two patients completed the 1-year follow-up. MMC-PRK eyes achieved better uncorrected visual acuity (p = 0.03) and better best-spectacle-corrected visual acuity (p<0.001) 1 year after surgery. SE did not differ in the two groups during follow-up (p = 0.12). Clinically significant haze was not found in surface ablation eyes. LASIK eyes showed a greater higher-order aberration (p = 0.01) and lower contrast sensitivity (p<0.05) than MMC-PRK eyes postoperatively. Excellent vision was reported in 64% of LASIK and 74% of MMC-PRK eyes 1 year after surgery. The corneal resistance factor and corneal hysteresis (ORA, Reichert) were higher in LASIK than in MMC-PRK eyes (p<0.01) at the last follow-up. Wavefront-guided PRK with 0.002% MMC was more effective than wavefront-guided LASIK for correction of moderate myopia. Further research is necessary to determine the optimal concentration, exposure time and long-term corneal side effect of MMC.

One-year outcomes of a bilateral randomised prospective clinical trial comparing PRK with mitomycin C and LASIK

PubMed Central

Wallau, A D; Campos, M

2009-01-01

Aim: To compare 1-year follow-up results of photorefractive keratectomy (PRK) with mitomycin C (MMC) and laser in situ keratomileusis (LASIK) for custom correction of myopia. Methods: Eighty-eight eyes of 44 patients with moderate myopia were randomised to PRK with 0.002% MMC for 1 min in one eye and LASIK in the fellow eye. The 1-year follow-up was evaluated. Results: There were no differences between LASIK and MMC-PRK eyes preoperatively. Forty-two patients completed the 1-year follow-up. MMC-PRK eyes achieved better uncorrected visual acuity (p = 0.03) and better best-spectacle-corrected visual acuity (p<0.001) 1 year after surgery. SE did not differ in the two groups during follow-up (p = 0.12). Clinically significant haze was not found in surface ablation eyes. LASIK eyes showed a greater higher-order aberration (p = 0.01) and lower contrast sensitivity (p<0.05) than MMC-PRK eyes postoperatively. Excellent vision was reported in 64% of LASIK and 74% of MMC-PRK eyes 1 year after surgery. The corneal resistance factor and corneal hysteresis (ORA, Reichert) were higher in LASIK than in MMC-PRK eyes (p<0.01) at the last follow-up. Conclusions: Wavefront-guided PRK with 0.002% MMC was more effective than wavefront-guided LASIK for correction of moderate myopia. Further research is necessary to determine the optimal concentration, exposure time and long-term corneal side effect of MMC. PMID:19889831

Wavefront-guided laser in situ keratomileusis (Lasik) versus wavefront-guided photorefractive keratectomy (Prk): a prospective randomized eye-to-eye comparison (an American Ophthalmological Society thesis).

PubMed

Manche, Edward E; Haw, Weldon W

2011-12-01

To compare the safety and efficacy of wavefront-guided laser in situ keratomileusis (LASIK) vs photorefractive keratectomy (PRK) in a prospective randomized clinical trial. A cohort of 68 eyes of 34 patients with -0.75 to -8.13 diopters (D) of myopia (spherical equivalent) were randomized to receive either wavefront-guided PRK or LASIK in the fellow eye using the VISX CustomVue laser. Patients were evaluated at 1 day, 1 week, and months 1, 3, 6, and 12. At 1 month, uncorrected visual acuity (UCVA), best spectacle-corrected visual acuity (BSCVA), 5% and 25% contrast sensitivity, induction of higher-order aberrations (HOAs), and subjective symptoms of vision clarity, vision fluctuation, ghosting, and overall self-assessment of vision were worse (P<0.05) in the PRK group. By 3 months, these differences had resolved (P>0.05). At 1 year, mean spherical equivalent was reduced 94% to -0.27 ± 0.31 D in the LASIK group and reduced 96% to -0.17 ± 0.41 D in the PRK group. At 1 year, 91% of eyes were within ±0.50 D and 97 % were within ±1.0 D in the PRK group. At 1 year, 88% of eyes were within ±0.50 D and 97% were within ±1.0 D in the LASIK group. At 1 year, 97% of eyes in the PRK group and 94% of eyes in the LASIK group achieved an UCVA of 20/20 or better (P=0.72). Refractive stability was achieved in both PRK and LASIK groups after 1 month. There were no intraoperative or postoperative flap complications in the LASIK group. There were no instances of corneal haze in the PRK group. Wavefront-guided LASIK and PRK are safe and effective at reducing myopia. At 1 month postoperatively, LASIK demonstrates an advantage over PRK in UCVA, BSCVA, low-contrast acuity, induction of total HOAs, and several subjective symptoms. At postoperative month 3, these differences between PRK and LASIK results had resolved.

Wavefront-Guided Laser in Situ Keratomileusis (Lasik) versus Wavefront-Guided Photorefractive Keratectomy (Prk): A Prospective Randomized Eye-to-Eye Comparison (An American Ophthalmological Society Thesis)

PubMed Central

Manche, Edward E.; Haw, Weldon W.

2011-01-01

Purpose To compare the safety and efficacy of wavefront-guided laser in situ keratomileusis (LASIK) vs photorefractive keratectomy (PRK) in a prospective randomized clinical trial. Methods A cohort of 68 eyes of 34 patients with −0.75 to −8.13 diopters (D) of myopia (spherical equivalent) were randomized to receive either wavefront-guided PRK or LASIK in the fellow eye using the VISX CustomVue laser. Patients were evaluated at 1 day, 1 week, and months 1, 3, 6, and 12. Results At 1 month, uncorrected visual acuity (UCVA), best spectacle-corrected visual acuity (BSCVA), 5% and 25% contrast sensitivity, induction of higher-order aberrations (HOAs), and subjective symptoms of vision clarity, vision fluctuation, ghosting, and overall self-assessment of vision were worse (P<0.05) in the PRK group. By 3 months, these differences had resolved (P>0.05). At 1 year, mean spherical equivalent was reduced 94% to −0.27 ± 0.31 D in the LASIK group and reduced 96% to −0.17 ± 0.41 D in the PRK group. At 1 year, 91% of eyes were within ±0.50 D and 97 % were within ±1.0 D in the PRK group. At 1 year, 88% of eyes were within ±0.50 D and 97% were within ±1.0 D in the LASIK group. At 1 year, 97% of eyes in the PRK group and 94% of eyes in the LASIK group achieved an UCVA of 20/20 or better (P=0.72). Refractive stability was achieved in both PRK and LASIK groups after 1 month. There were no intraoperative or postoperative flap complications in the LASIK group. There were no instances of corneal haze in the PRK group. Conclusions Wavefront-guided LASIK and PRK are safe and effective at reducing myopia. At 1 month postoperatively, LASIK demonstrates an advantage over PRK in UCVA, BSCVA, low-contrast acuity, induction of total HOAs, and several subjective symptoms. At postoperative month 3, these differences between PRK and LASIK results had resolved. PMID:22253488

[Complications after refractive surgery abroad].

PubMed

Terzi, E; Kern, T; Kohnen, T

2008-05-01

In this article a retrospective analysis of patients presenting at a German university following refractive surgery abroad is presented. A total of 20 cases of patients who had undergone treatment between 1998 and 2006 in China (1 case), Greece (1 case), Iran (1 case), Russia (2 cases), Switzerland (1 case), Slovakia (1 case), Spain (2 cases), South Africa (3 cases), Turkey (6 cases) and the USA (2 cases) were analyzed retrospectively. The following complications were observed: epithelial ingrowth into the interface with or without melting of the flap (6 cases), corneal ectasia (2 cases), dislocation of a phakic posterior chamber intraocular lens and prolapse into the anterior chamber with endothelial cell loss (1 case), secondary increase of intraocular pressure following implantation of a phakic intraocular lens (1 case), flap-related complications following laser-in-situ keratomileusis (LASIK) (2 cases), keratitis (1 case), dislocation of the complete flap (1 case), diffuse lamellar keratitis (DLK) grade IV (1 case), hyperopia as a consequence of radial keratotomy (1 case), and under correction/over correction and poor optical quality following laser epithelial keratomileusis (LASEK) and LASIK for high myopia (5 cases) with possible early corneal ectasia. There are four important problems arising from refractive surgery abroad, often referred to as "LASIK tourism": wrong indications, insufficient management of complications, lack of postoperative care and the health economic aspect.

[Analysis of AC/A ratio after myopic excimer laser in situ keratomileusis].

PubMed

Wu, Xiao-ying; Liu, Shuang-zhen

2003-03-01

To study the changes of AC/A ratio of myopia after excimer laser in situ keratomileusis (LASIK). 135 myopia patients were treated by LASIK, their AC/A ratios were measured with synoptohore before surgery and 3 months after surgery. The average AC/A ratios of naked eyes or eyes wearing glasses before surgery and the naked after surgery were (0.724 +/- 0.587) (Delta)/D, (2.754 +/- 1.565) (Delta)/D, (1.618 +/- 1.027) (Delta)/D in turn. There were significant difference among those groups (P < 0.001). That also appeared in different degree of myopia naked before surgery (P < 0.01). We found no significant difference between the groups wearing glasses before surgery and naked after surgery (P > 0.05). A positive correlation was built up between postoperative AC/A ratio and AC/A ratio of wearing glasses or refractive diopter before surgery (r = 0.550, P < 0.001; r = 0.185, P < 0.005). And the postoperative AC/A ratios had a negative correlation to age or length of ocular axis (r = -0.340, P < 0.001; r = -0.192, P < 0.002). The regression equation for postoperative AC/A ratios was figured out as Y((Delta)/D) = 4.080 0 - 0.031 8X(1) - 0.097 1X(2) + 0.325 0X(3) (P < 0.001). X(1) = age (year), X(2) = length of ocular axis (mm), X(3) = preoperative AC/A ratio with weaning glasses ((Delta)/D). The naked AC/A ratios are higher than the preoperative's after LASIK, but lower than the wearing glasses's before surgery. It is influenced by the factors, such as: the preoperative AC/A ratio of wearing glasses, the length of ocular axis and the age.

Anterior chamber gas bubble emergence pattern during femtosecond LASIK-flap creation.

PubMed

Robert, Marie-Claude; Khreim, Nour; Todani, Amit; Melki, Samir A

2015-09-01

To characterise the emergence pattern of cavitation bubbles into the anterior chamber (AC) following femtosecond laser-assisted in situ keratomileusis (LASIK)-flap creation Retrospective review of patients undergoing femtosecond LASIK surgery at Boston Laser, a private refractive surgery practice in Boston, Massachusetts, between December 2008 and February 2014. Patient charts were reviewed to identify all cases with gas bubble migration into the AC. Surgical videos were examined and the location of bubble entry was recorded separately for right and left eyes. Five thousand one hundred and fifty-eight patients underwent femtosecond LASIK surgery. Air bubble migration into the AC, presumably via the Schlemm's canal and trabecular meshwork, occurred in 1% of cases. Patients with AC bubbles had an average age of 33±8 years with a measured LASIK flap thickness of 96±21 μm. The occurrence of gas bubbles impaired iris registration in 64% of cases. Gas bubbles appeared preferentially in the nasal or inferior quadrants for right (92% of cases) and left (100% of cases) eyes. This bubble emergence pattern is significantly different from that expected with a random distribution (p<0.0001) and did not seem associated with decentration of the femtosecond laser docking system. The migration of gas bubbles into the AC is a rare occurrence during femtosecond laser flap creation. The preferential emergence of gas bubbles into the nasal and inferior quadrants of the AC may indicate a distinctive anatomy of the nasal Schlemm's canal. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://group.bmj.com/group/rights-licensing/permissions.

Stereoacuity changes after laser in situ keratomileusis.

PubMed

Singh, Digvijay; Saxena, Rohit; Sinha, Rajesh; Titiyal, Jeewan S

2015-02-01

To study changes in near and distance stereoacuity after laser in situ keratomileusis (LASIK). A prospective interventional study was conducted at an apex tertiary care ophthalmology center in India. Near and distance stereoacuity was tested in 40 patients (80 eyes) who underwent LASIK for myopic correction and got unaided vision of 0.67 or better in each eye. Stereoacuity was tested with best spectacle correction before LASIK, and post-LASIK stereoacuity was tested with unaided eye near and distance Randot tests. Forty patients (80 eyes) had a mean (±SD) pre-LASIK refractive error of -4.70 (±1.72) DS OD and -4.59 (±1.58) DS OS and a mean (±SD) anisometropia of 0.55 (±0.51) DS. The median pre-LASIK near stereoacuity was 70 arcsec and distance stereoacuity was 200 arcsec, both of which improved after LASIK to 30 and 60 arcsec, respectively (p < 0.001, both). Amount of refractive error was not associated with stereoacuity but anisometropia of greater than or equal to 1 diopter had significantly worse distance stereoacuity in both the pre-LASIK and post-LASIK period. The post-LASIK near stereoacuity and distance stereoacuity were strongly associated (r = 0.706, p < 0.001) unlike the change in stereoacuity. Near and distance stereoacuity shows significant improvement after LASIK. Stereoacuity is associated with the degree of anisometropia but not the amount of refractive error corrected.

Sequential lift and suture technique for post-LASIK corneal striae.

PubMed

Mackool, Richard J; Monsanto, Vivian R

2003-04-01

We describe a surgical technique to manage persistent corneal striae after laser in situ keratomileusis (LASIK). The sequential lift and suture technique reduces the time required for LASIK, eliminates the need to fixate the flap with forceps during suturing, and increases the accuracy of suture placement. The results in 10 eyes (9 patients) showed complete resolution of striae with improvement in subjective symptoms (glare and blurred vision) and best corrected visual acuity.

The effect of flap thickness on corneal biomechanics after myopic laser in situ keratomileusis using the M-2 microkeratome

PubMed Central

Goussous, Iyad A; El-Agha, Mohamed-Sameh; Awadein, Ahmed; Hosny, Mohamed H; Ghaith, Alaa A; Khattab, Ahmed L

2017-01-01

Purpose The purpose of this study was to determine the effect of flap thickness on corneal biomechanics after myopic laser in situ keratomileusis (LASIK). Methods This is a prospective controlled non-randomized, institutional study. Patients underwent either epi-LASIK with mitomycin (advanced surface ablation [ASA]), thin-flap LASIK (90 µm head), or thick-flap LASIK (130 µm head). In ASA, the Moria Epi-K hydroseparator was used. LASIK flaps were created using the Moria M-2 mechanical microkeratome. The corneal hysteresis (CH) and corneal resistance factor (CRF) were measured preoperatively and 3 months after surgery, using the Ocular Response Analyzer®. Results Ten patients (19 eyes) underwent ASA, 11 patients (16 eyes) underwent thin-flap LASIK, and 11 patients (16 eyes) underwent thick-flap LASIK. The mean preoperative CH was 10.47±0.88, 10.52±1.4, and 11.28±1.4 mmHg (p=0.043), respectively, decreasing after surgery by 1.75±1.02, 1.66±1.00, and 2.62±1.03 mmHg (p=0.017). The mean reduction of CH per micron of central corneal ablation was 0.031, 0.023, and 0.049 mmHg/µm (p=0.005). Mean preoperative CRF was 10.11±1.28, 10.34±1.87, and 10.62±1.76 mmHg (p=0.66), decreasing after surgery by 2.33±1.35, 2.77±1.03, and 2.92±1.10 mmHg (p=0.308). The mean reduction of CRF per micron of central corneal ablation was 0.039, 0.040, and 0.051 mmHg/µm (p=0.112). Conclusion Thick-flap LASIK caused a greater reduction of CH and CRF than thin-flap LASIK and ASA, although this was statistically significant only for CH. ASA and thin-flap LASIK were found to be biomechanically similar. PMID:29200820

Efficacy and perioperative timing of bromfenac in the management of ocular discomfort after femtosecond laser-assisted laser in situ keratomileusis.

PubMed

Cleaveland, Nathan A; De Mann, Derek W; Carlson, Neil E; Keil, Michael L

2017-02-01

To evaluate the safety, efficacy, and appropriate perioperative timing of the use of topical bromfenac ophthalmic solution 0.07% after femtosecond laser-assisted laser in situ keratomileusis (LASIK). Keil LASIK Vision Center, Grand Rapids, Michigan, USA. Prospective case series. Ocular discomfort was assessed 1, 2, and 5 hours postoperatively and the following morning using the Ocular Comfort Grading Assessment in patients treated with topical bromfenac 0.07% or artificial tears just before, just after, or before and after femtosecond laser-assisted LASIK. Visual outcomes and complications were noted up to 24 hours. The study enrolled 64 patients (120 eyes). Patients who were treated with bromfenac 0.07% just before or before and after femtosecond laser-assisted LASIK showed the greatest statistically significant decrease in several discomfort scores within the first few hours in comparison with the control group. Two hours after surgery, the majority of patients who were treated before and after LASIK were sleeping comfortably. There were no significant differences in visual acuity; 1 day postoperatively, the uncorrected distance visual acuity was 20/20 in 106 eyes (89%) and 20/25 or better in 116 eyes (97%). At 3 months, all patients had binocular distance visual acuity of 20/20 or better and 86% of patients had 20/15 or better. Ocular discomfort after femtosecond laser-assisted LASIK was reduced with a single dose of topical bromfenac 0.07% given immediately before surgery or given just before and after surgery and was typically minimal in all groups the morning after surgery. Copyright © 2017 ASCRS and ESCRS. Published by Elsevier Inc. All rights reserved.

Factors Affecting Long-term Myopic Regression after Laser In Situ Keratomileusis and Laser-assisted Subepithelial Keratectomy for Moderate Myopia.

PubMed

Lim, Sung A; Park, Yooyeon; Cheong, Yu Jin; Na, Kyung Sun; Joo, Choun-Ki

2016-04-01

High myopia is known to be a risk factor for long-term regression after laser refractive surgery. There have been few studies about the correction of moderate myopias that did not need retreatment after long-term follow-up. We evaluated 10 years of change in visual acuity and refractive power in eyes with moderate myopia after laser refractive surgery. We included patients that had undergone laser in situ keratomileusis (LASIK) or laser-assisted subepithelial keratectomy (LASEK) to correct their myopia and that had at least 10 years of follow-up. We evaluated the stability of visual acuity in terms of safety, efficacy, and refractive changes at examinations 6 months and 1, 2, 5, 7, and 10 years after surgery. The study evaluated 62 eyes (36 eyes in LASIK patients and 26 eyes in LASEK patients). In both groups, the efficacy index tended to decrease, and it was consistently higher in the LASEK group compared to the LASIK group over the 10 years of follow-up. The safety index improved over 10 years and was always higher than 0.9 in both groups. The difference between the spherical equivalent at 6 months postoperatively and later periods was statistically significant after 5, 7, and 10 years in both groups (LASIK, p = 0.036, p = 0.003, and p < 0.001, respectively; LASEK, p = 0.006, p = 0.002, and p = 0.001, respectively). Ten years after surgery,26 eyes (66.7%) in the LASIK group and 19 eyes (73.1%) in the LASEK group had myopia greater than 1 diopter. In comparison with the thickness at 6 months postoperatively, central corneal thickness was significantly increased after 5, 7, and 10 years in both LASIK and LASEK groups (LASIK, p < 0.001, p < 0.001, and p < 0.001, respectively; LASEK, p = 0.01, p < 0.001, and p < 0.001, respectively). Moderately myopic eyes showed progressive myopic shifting and corneal thickening after LASIK and LASEK during 10 years of follow-up. We also found that early refractive regression may indicate the long-term refractive outcome.

Combined laser in-situ keratomileusis and accelerated corneal cross-linking: an update.

PubMed

Tomita, Minoru

2016-07-01

The purpose is to review the literature of combined laser in-situ keratomileusis (LASIK) and accelerated corneal collagen cross-linking (CXL) in context of its indications-contraindications, kerato-refractive, visual and safety outcomes, particularly with reference to preventing the development of post-LASIK ectasia. LASIK + accelerated CXL has been developed with the rationale that the addition of CXL after LASIK may strengthen the LASIK compromised corneal biomechanics and minimize the complications such as post-LASIK ectasia. Different clinical studies have documented the safety and efficacy of LASIK + accelerated CXL for the correction of myopia or hyperopia and in the patients with low predicted residual bed thickness. Available literature shows that refractive and keratometric outcomes of LASIK + accelerated CXL are comparable or better than LASIK alone. Less regression has been observed after LASIK + accelerated CXL compared with LASIK alone and no case of post-LASIK ectasia development has been reported among 673 eyes with the follow-up ranging from 3 months to 4.5 years. Future studies with large numbers of patients and longer postoperative follow-ups are needed to establish the efficacy of LASIK + accelerated CXL in preventing the development of post-LASIK ectasia.

A prospective, contralateral comparison of photorefractive keratectomy (PRK) versus thin-flap LASIK: assessment of visual function.

PubMed

Hatch, Bryndon B; Moshirfar, Majid; Ollerton, Andrew J; Sikder, Shameema; Mifflin, Mark D

2011-01-01

To compare differences in visual acuity, contrast sensitivity, complications, and higher-order ocular aberrations (HOAs) in eyes with stable myopia undergoing either photo-refractive keratectomy (PRK) or thin-flap laser in situ keratomileusis (LASIK) (intended flap thickness of 90 μm) using the VISX Star S4 CustomVue excimer laser and the IntraLase FS60 femtosecond laser at 1, 3, and 6 months postoperatively. In this prospective, masked, and randomized pilot study, refractive surgery was performed contralaterally on 52 eyes: 26 with PRK and 26 with thin-flap LASIK. Primary outcome measures were uncorrected distance visual acuity (UDVA), corrected distance visual acuity (CDVA), contrast sensitivity, and complications. At 6 months, mean values for UDVA (logMAR) were -0.043 ± 0.668 and -0.061 ± 0.099 in the PRK and thin-flap LASIK groups, respectively (n = 25, P = 0.466). UDVA of 20/20 or better was achieved in 96% of eyes undergoing PRK and 92% of eyes undergoing thin-flap LASIK, whereas 20/15 vision or better was achieved in 73% of eyes undergoing PRK and 72% of eyes undergoing thin-flap LASIK (P > 0.600). Significant differences were not found between treatment groups in contrast sensitivity (P ≥ 0.156) or CDVA (P = 0.800) at postoperative 6 months. Types of complications differed between groups, notably 35% of eyes in the thin-flap LASIK group experiencing complications, including microstriae and 2 flap tears. Under well-controlled surgical conditions, PRK and thin-flap LASIK refractive surgeries achieve similar results in visual acuity, contrast sensitivity, and induction of HOAs, with differences in experienced complications.

A prospective, contralateral comparison of photorefractive keratectomy (PRK) versus thin-flap LASIK: assessment of visual function

PubMed Central

Hatch, Bryndon B; Moshirfar, Majid; Ollerton, Andrew J; Sikder, Shameema; Mifflin, Mark D

2011-01-01

Purpose: To compare differences in visual acuity, contrast sensitivity, complications, and higher-order ocular aberrations (HOAs) in eyes with stable myopia undergoing either photo-refractive keratectomy (PRK) or thin-flap laser in situ keratomileusis (LASIK) (intended flap thickness of 90 μm) using the VISX Star S4 CustomVue excimer laser and the IntraLase FS60 femtosecond laser at 1, 3, and 6 months postoperatively. Methods: In this prospective, masked, and randomized pilot study, refractive surgery was performed contralaterally on 52 eyes: 26 with PRK and 26 with thin-flap LASIK. Primary outcome measures were uncorrected distance visual acuity (UDVA), corrected distance visual acuity (CDVA), contrast sensitivity, and complications. Results: At 6 months, mean values for UDVA (logMAR) were −0.043 ± 0.668 and −0.061 ± 0.099 in the PRK and thin-flap LASIK groups, respectively (n = 25, P = 0.466). UDVA of 20/20 or better was achieved in 96% of eyes undergoing PRK and 92% of eyes undergoing thin-flap LASIK, whereas 20/15 vision or better was achieved in 73% of eyes undergoing PRK and 72% of eyes undergoing thin-flap LASIK (P > 0.600). Significant differences were not found between treatment groups in contrast sensitivity (P ≥ 0.156) or CDVA (P = 0.800) at postoperative 6 months. Types of complications differed between groups, notably 35% of eyes in the thin-flap LASIK group experiencing complications, including microstriae and 2 flap tears. Conclusion: Under well-controlled surgical conditions, PRK and thin-flap LASIK refractive surgeries achieve similar results in visual acuity, contrast sensitivity, and induction of HOAs, with differences in experienced complications. PMID:21573091

Nerve growth factor concentration and implications in photorefractive keratectomy vs laser in situ keratomileusis.

PubMed

Lee, Hyung Keun; Lee, Kyung Sub; Kim, Hyeon Chang; Lee, Sung Ho; Kim, Eung Kweon

2005-06-01

To determine whether tear nerve growth factor (NGF) concentration correlates with corneal sensation and ocular surface dryness after photorefractive keratectomy (PRK) and laser in situ keratomileusis (LASIK). Prospective, nonrandomized comparative clinical trial. Seventy eyes of 35 patients and 76 eyes of 38 patients underwent PRK and LASIK procedures to correct myopia and myopic astigmatism, respectively. Total tear protein level, tear NGF concentration, tear film breakup time (BUT) and Schirmer values were measured before and 1 day, 1 week, 1 month, 3 months, and 6 months after surgery. The postoperative mean tear NGF/total tear protein (NGF/tP) ratio increased in both PRK and LASIK patients compared with preoperative levels (P < .0001). At 1 week and 1 month postoperatively, the NGF/tP ratio was higher in PRK than in LASIK subjects (P < .0001). Before 6 months postoperatively, the mean corneal sensation after LASIK in the ablated zone was lower than the preoperative sensation (P < .0001), but this was not the case in PRK subjects. Mean BUT and Schirmer values were significantly lower in LASIK-treated eyes compared with PRK-treated eyes up to 6 months postoperatively (P < .0001). The early postoperative tear NGF/tP ratio correlated with the postoperative 6-month value of corneal sensation, BUT, and Schirmer values. The difference in the postoperative corneal sensation and ocular surface dryness between PRK-treated and LASIK-treated eyes might be related to the difference in the early postoperative levels of NGF, which is a potent nerve growth stimulator.

Reasons For Not Performing Keratorefractive Surgery in Patients Seeking Refractive Surgery in a Hospital-Based Cohort in “Yemen”

PubMed Central

Bamashmus, Mahfouth A.; Saleh, Mahmoud F.; Awadalla, Mohamed A.

2010-01-01

Background: To determine and analyze the reasons why keratorefractive surgery, laser in situ keratomileusis (LASIK) and photorefractive keratectomy (PRK) were not performed in patients who presented for refractive surgery consultation. Materials and Methods: A retrospective observational study was performed between January 2006 and December 2007 in the Yemen Magrabi Hospital. The case records of 2,091 consecutive new patients who presented for refractive surgery were reviewed. Information from the pre-operative ophthalmic examination, such as refractive error, corneal topography and visual acuity, were analyzed. The reasons for not performing LASIK and PRK in the cases that were rejected were recorded and analyzed. Results: In this cohort, 1,660 (79.4%) patients were advised to have LASIK or PRK from the 2,091 patients examined. LASIK and PRK were not advised in 431 (21%) patients. The most common reasons for not performing the surgery were high myopia >-11.00 Diopters (19%), keratoconus (18%), suboptimal central corneal thickness (15%), cataract (12%) and keratoconus suspect (forme fruste keratoconus) (10%). Conclusion: Patients who requested keratorefractive surgery have a variety of problems and warrant comprehensive attention to selection criteria on the part of the surgeon. Corneal topographies and pachymetry of refractive surgery candidates need to be read cautiously. High-refractive error, keratoconus and insufficient corneal thickness were found to be the leading reasons for not performing keratorefractive surgery in this study. PMID:21180437

Femtosecond-Assisted LASIK Versus PRK: Comparison of 6-Month Visual Acuity and Quality Outcome for High Myopia.

PubMed

Hashemi, Hassan; Miraftab, Mohammad; Ghaffari, Reza; Asgari, Soheila

2016-11-01

To compare the results of femtosecond-assisted laser in situ keratomileusis (femto-LASIK) and photorefractive keratectomy with mitomycin C (PRK-MMC) for the correction of myopia more than 7.0 diopters (D). In this comparative nonrandomized trial, 60 eyes (30 eyes in each group) were enrolled. Patients were tested for uncorrected distance visual acuity (UDVA), corrected distance visual acuity (CDVA), manifest refraction spherical equivalent, ocular and corneal aberrations, and contrast sensitivity (CS) before surgery and at 3 and 6 months postoperatively. Mean preoperative myopia was -8.65±1.51 and -8.04±1.70 D in the femto-LASIK and PRK-MMC groups, respectively (P=0.149). Intergroup differences in baseline indices were not statistically significant. At 6 months after surgery, UDVA showed an improving trend, but it was better in the femto-LASIK group (P=0.026). CDVA in the two groups remained similarly unchanged (P=0.170). For the femto-LASIK and PRK-MMC groups, the safety indices were 1.01±0.05 and 1.01±0.14 (P=0.949), respectively, and the efficacy indices were 0.99±0.07 and 0.93±0.22 (P=0.192), respectively. Comparing CS, only CS18 showed a significantly greater decrease in the femto-LASIK group compared with the PRK-MMC group (P=0.016). Intergroup differences were not statistically significant in other spatial frequencies. Changes in the ocular and corneal higher order aberrations were not statistically different between the two groups except ocular coma, which increased in the femto-LASIK group (P=0.041). Femto-LASIK improves UDVA better than PRK-MMC in high myopia. However, because of increased coma, the quality of vision is reduced. In other words, visual acuity outcome is better with femto-LASIK and visual quality outcome is better with PRK-MMC.

Change in the accommodative convergence per unit of accommodation ratio after bilateral laser in situ keratomileusis for myopia in orthotropic patients: prospective evaluation.

PubMed

Prakash, Gaurav; Choudhary, Vandana; Sharma, Namrata; Titiyal, Jeewan S

2007-12-01

To analyze the effect of bilateral laser in situ keratomileusis (LASIK) on the accommodative convergence per unit of accommodation (AC/A) ratio in otherwise normal orthotropic myopic patients. Cornea and refractive services of a tertiary-care ophthalmic center. This prospective clinical trial consisted of 61 myopic patients who had bilateral LASIK. Those with manifest tropia, previous squint surgery, amblyopia, or absent or impaired binocularity or those in whom monovision was planned were excluded. The preoperative examination included visual acuity, cycloplegic refraction, assessment of binocularity, a prism cover test, and evaluation of the stimulus AC/A ratio by the gradient method. All patients had LASIK using the Zyoptix platform (Bausch & Lomb). Postoperative evaluation included uncorrected and best corrected visual acuities, residual refraction, and the AC/A ratio. All patients had a follow-up of 9 months. There was significant decrease in the mean AC/A ratio at the 1-week and 1-month follow-ups. The AC/A progressively recovered to near preoperative values between 3 months and 9 months after surgery (analysis of variance test). There was a significant reduction in the number of symptomatic patients from the first month onward (chi square = 89.23; P<.001). The AC/A ratio varied after LASIK, stabilizing between 3 months and 9 months after surgery. This suggests that the maximum variation in the accommodation-convergence relationship after LASIK occurs in the first 3 months.

Retinal measurements using time domain optical coherence tomography imaging before and after myopic Lasik

PubMed Central

Lei, Feng; Burns, Stephen A.; shao, Liqin; Yang, Yabo

2014-01-01

Purpose To compare retinal measurements obtained by time domain optical coherence tomography (OCT) devices before and after myopic laser in situ keratomileusis (Lasik) and to assess the interaction of Lasik and retinal structures as measured by time domain OCT. Methods 53 patients randomly selected participated in the study. Only the right eye of each subject was included in the study. Comprehensive ophthalmic examinations including refraction examination, slitlamp examination, dilated fundus examination, corneal topography, corneal thickness, intraocular pressure, and retinal Stratus OCT scans were acquired for each patient before myopic Lasik and 3 months after surgery. Results Total macular volume (TMV) changed significantly between preoperative and postoperative measurements (p=0.003). No statistical differences were found between preoperative and postoperative disc area, rim area, cup/disk vert. ratio, or average foveal thickness (p>0.05). The variation in TMV correlated significantly with the change in spherical refraction equivalent, maximal corneal curvature, minimal corneal curvature, and corneal ablation depth. Conclusion Most retinal OCT measurements undergo no obvious changes after myopic Lasik. The increased TMV measurements we measured after Lasik seem to be correlated with the alteration in corneal shape. The exact mechanism for this change is not clear, while we examined several possibilities including subclinical macular edema, magnification changes, errors in OCT analysis and IOP, none of these seem to be a likely cause. PMID:22512373

Corneal scarring from laser in situ keratomileusis after epikeratoplasty: Clinical and histopathologic analysis

PubMed Central

Khandelwal, Sumitra S.; Randleman, J. Bradley; Grossniklaus, Hans E.

2015-01-01

A 47-year-old woman required penetrating keratoplasty in the right eye after developing delayed visually significant corneal scarring bilaterally after laser in situ keratomileusis (LASIK) in 1997 following epikeratoplasty in 1987. Spectral domain ocular coherence tomography of the left cornea showed a 100 μm lenticule with a LASIK flap posterior to the host Bowman layer at 250 μm. Histopathology and electron microscopy of the right corneal button showed a 120 μm lenticule with a LASIK flap within the lenticule at 100 μm. Clinically significant scarring was present within the LASIK flap interface, within the lenticule stroma, and within the area of the underlying host Bowman layer. There were keratocytes at the junction between the LASIK flap and lenticule stromal bed. Although epikeratoplasty is no longer practiced, post-epikeratoplasty patients may present for refractive surgical options and LASIK carries significant risks for corneal scarring in these individuals, especially when using flap-creating devices that may create thin LASIK flaps. PMID:23506924

Factors Affecting Long-term Myopic Regression after Laser In Situ Keratomileusis and Laser-assisted Subepithelial Keratectomy for Moderate Myopia

PubMed Central

Lim, Sung A; Park, Yooyeon; Cheong, Yu Jin; Na, Kyung Sun

2016-01-01

Purpose High myopia is known to be a risk factor for long-term regression after laser refractive surgery. There have been few studies about the correction of moderate myopias that did not need retreatment after long-term follow-up. We evaluated 10 years of change in visual acuity and refractive power in eyes with moderate myopia after laser refractive surgery. Methods We included patients that had undergone laser in situ keratomileusis (LASIK) or laser-assisted subepithelial keratectomy (LASEK) to correct their myopia and that had at least 10 years of follow-up. We evaluated the stability of visual acuity in terms of safety, efficacy, and refractive changes at examinations 6 months and 1, 2, 5, 7, and 10 years after surgery. Results The study evaluated 62 eyes (36 eyes in LASIK patients and 26 eyes in LASEK patients). In both groups, the efficacy index tended to decrease, and it was consistently higher in the LASEK group compared to the LASIK group over the 10 years of follow-up. The safety index improved over 10 years and was always higher than 0.9 in both groups. The difference between the spherical equivalent at 6 months postoperatively and later periods was statistically significant after 5, 7, and 10 years in both groups (LASIK, p = 0.036, p = 0.003, and p < 0.001, respectively; LASEK, p = 0.006, p = 0.002, and p = 0.001, respectively). Ten years after surgery,26 eyes (66.7%) in the LASIK group and 19 eyes (73.1%) in the LASEK group had myopia greater than 1 diopter. In comparison with the thickness at 6 months postoperatively, central corneal thickness was significantly increased after 5, 7, and 10 years in both LASIK and LASEK groups (LASIK, p < 0.001, p < 0.001, and p < 0.001, respectively; LASEK, p = 0.01, p < 0.001, and p < 0.001, respectively). Conclusions Moderately myopic eyes showed progressive myopic shifting and corneal thickening after LASIK and LASEK during 10 years of follow-up. We also found that early refractive regression may indicate the long

Macroeconomic landscape of refractive surgery in the United States.

PubMed

Corcoran, Kevin J

2015-07-01

This review examines the economic history of refractive surgery and the decline of laser-assisted in-situ keratomileusis (LASIK) in the USA, and the emergence of refractive cataract surgery as an area of growth. Since it peaked in 2007 at 1.4 million procedures per year, LASIK has declined 50% in the USA, whereas refractive cataract surgery, including presbyopia-correcting intraocular lenses (IOLs), astigmatism-correcting IOLs, and femtosecond laser-assisted cataract surgery, has grown to 350 000 procedures per year, beginning in 2003. Patients are price-sensitive and responsive to publicity (good or bad) about refractive surgery and refractive cataract surgery. LASIK's decline has been partially offset by the emergence of refractive cataract surgery. About 11% of all cataract surgery in the USA involves presbyopia-correcting IOLs, astigmatism-correcting IOLs, or a femtosecond laser. From the surgeon's perspective, there are high barriers to entry into the marketplace for refractive surgery and refractive cataract surgery due to the high capital cost of excimer and femtosecond lasers, the high skill level required to deliver spectacular results to demanding patients who pay out of pocket, and the necessity to perform a high volume of surgeries to satisfy both of these requirements. Probably, less than 7% of US cataract surgeons can readily meet all of these requirements.

Chronic dry eye in photorefractive keratectomy and laser in situ keratomileusis: Manifestations, incidence, and predictive factors.

PubMed

Bower, Kraig S; Sia, Rose K; Ryan, Denise S; Mines, Michael J; Dartt, Darlene A

2015-12-01

To evaluate dry-eye manifestations after photorefractive keratectomy (PRK) and laser in situ keratomileusis (LASIK) and determine the incidence and predictive factors of chronic dry eye using a set of dry-eye criteria. Walter Reed Army Medical Center, Washington, DC, USA. Prospective, non-randomized clinical study. Dry-eye evaluation was performed before and after surgery. Main outcome measures included dry-eye manifestations, incidence, and predictive factors of chronic dry eye. This study comprised 143 active-duty U.S. Army personnel, ages 29.9 ± 5.2 years, with myopia or myopic astigmatism (manifest spherical equivalent -3.83 ± 1.96 diopters) having PRK or LASIK. Schirmer scores, corneal sensitivity, ocular surface staining, surface regularity index, and responses to dry-eye questionnaire significantly changed over time after PRK. After LASIK, significant changes were observed in tear breakup time, corneal sensitivity, ocular surface staining, and responses to questionnaire. Twelve months postoperatively, 5.0% of PRK and 0.8% of LASIK participants developed chronic dry eye. Regression analysis showed that pre-operatively lower Schirmer score will significantly influence development of chronic dry eye after PRK, whereas preoperatively, lower Schirmer score or higher ocular surface staining score will significantly influence the occurrence of chronic dry eye after LASIK. Chronic dry eye was uncommon after PRK and LASIK. Ocular surface and tear-film characteristics during pre-operative examination might help to predict chronic dry-eye development in PRK and LASIK. The authors have no financial interest in any product, drug, instrument, or equipment discussed in this manuscript. Copyright © 2015 ASCRS and ESCRS. All rights reserved.

Femtosecond laser refractive surgery: small-incision lenticule extraction vs. femtosecond laser-assisted LASIK.

PubMed

Lee, Jimmy K; Chuck, Roy S; Park, Choul Yong

2015-07-01

Small-incision lenticule extraction (SMILE) is a novel technique devised to correct refractive errors. SMILE circumvents excimer laser photoablation of cornea, as the stromal lenticule cut by femtosecond laser is removed manually. Smaller incisions and preservation of anterior corneal biomechanical strength have been suggested as some of the advantages of SMILE over femtosecond laser-assisted LASIK (FS-LASIK). In this review, we compared previous published results of SMILE and FS-LASIK. The advantage, efficacy and safety of SMILE are compared with FS-LASIK. SMILE achieved similar efficacy, predictability and safety as FS-LASIK. Greater preservations of corneal biomechanical strength and corneal nerves were observed in SMILE when compared with LASIK or PRK. Additionally, the incidence of postoperative dry eye syndrome was found to be less problematic in SMILE than in FS-LASIK. SMILE is a promising new surgery for refractive error correction. Prospective and retrospective studies of SMILE have shown that results of SMILE are similar to FS-LASIK. With advances in femtosecond laser technology, SMILE may gain greater acceptance in the future.

Cox proportional hazards model of myopic regression for laser in situ keratomileusis flap creation with a femtosecond laser and with a mechanical microkeratome.

PubMed

Lin, Meng-Yin; Chang, David C K; Hsu, Wen-Ming; Wang, I-Jong

2012-06-01

To compare predictive factors for postoperative myopic regression between laser in situ keratomileusis (LASIK) with a femtosecond laser and LASIK with a mechanical microkeratome. Nobel Eye Clinic, Taipei, Taiwan. Retrospective comparative study. Refractive outcomes were recorded 1 day, 1 week, and 1, 3, 6, 9, and 12 months after LASIK. A Cox proportional hazards model was used to evaluate the impact of the 2 flap-creating methods and other covariates on postoperative myopic regression. The femtosecond group comprised 409 eyes and the mechanical microkeratome group, 377 eyes. For both methods, significant predictors for myopic regression after LASIK included preoperative manifest spherical equivalent (P=.0001) and central corneal thickness (P=.027). Laser in situ keratomileusis with a mechanical microkeratome had a higher probability of postoperative myopic regression than LASIK with a femtosecond laser (P=.0002). After adjusting for other covariates in the Cox proportional hazards model, the cumulative risk for myopic regression with a mechanical microkeratome was higher than with a femtosecond laser 12 months postoperatively (P=.0002). With the definition of myopic regression as a myopic shift of 0.50 diopter (D) or more and residual myopia of -0.50 D or less, the risk estimate based on the mean covariates in all eyes in the femtosecond group and mechanical microkeratome group at 12 months was 43.6% and 66.9%, respectively. Laser in situ keratomileusis with a mechanical microkeratome had a higher risk for myopic regression than LASIK with a femtosecond laser through 12 months postoperatively. Copyright © 2012. Published by Elsevier Inc.

Ten years after photorefractive keratectomy (PRK) and laser in situ keratomileusis (LASIK) for moderate to high myopia (control-matched study).

PubMed

Alió, J L; Ortiz, D; Muftuoglu, O; Garcia, M J

2009-10-01

To compare the long-term outcomes of photorefractive keratectomy (PRK) and laser in situ keratomilesis (LASIK) for myopia between -6 and -10 D. A retrospective, control-matched study including 68 eyes, 34 which underwent PRK and 34 LASIK, with myopia between -6 and -10 D, operated using the VISX 20/20 excimer laser, was performed. Optical zones of 5.5 to 6 mm were used. All PRK-treated eyes were matched with LASIK-treated eyes of the same age, spherical equivalent within +/-1.25 D, sphere within +/-1.5 D and cylinder within +/-2.5 D. All patients were evaluated 3 months, 1 year, 2 years, 5 years and 10 years after surgery. The main outcomes measures were refractive predictability and stability, safety, efficacy and re-treatment rate. At 10 years, 20 (71%) and 23 (88%) were within +/-1.00 D after PRK and LASIK respectively. The re-treatment rate was 35% and 18% respectively. No eye lost more than two lines of BSCVA in both groups. The efficacy was 0.90 for PRK and 0.95 for LASIK. Both PRK and LASIK were safe for moderate myopia. LASIK demonstrated slightly better efficacy, predictability, and less rate of re-treatment after 10 years. The technical improvements should be taken into account when comparing these results with those obtained more recently.

Combination therapy with diquafosol tetrasodium and sodium hyaluronate in patients with dry eye after laser in situ keratomileusis.

PubMed

Toda, Ikuko; Ide, Takeshi; Fukumoto, Teruki; Ichihashi, Yoshiyuki; Tsubota, Kazuo

2014-03-01

To evaluate the possible advantages of combination therapy with diquafosol tetrasodium and sodium hyaluronate for dry eye after laser in situ keratomileusis (LASIK). Prospective randomized comparative trial. A total of 206 eyes of 105 patients who underwent LASIK were enrolled in this study. Patients were randomly assigned to 1 of 4 treatment groups according to the postoperative treatment: artificial tears, sodium hyaluronate, diquafosol tetrasodium, and a combination of hyaluronate and diquafosol. Questionnaire responses reflecting subjective dry eye symptoms, uncorrected and corrected visual acuity, functional visual acuity, manifest refraction, tear break-up time, fluorescein corneal staining, Schirmer test, and corneal sensitivity were examined before and 1 week and 1 month after LASIK. Distance uncorrected visual acuity was significantly better in the combination group than in the hyaluronate group 1 week and 1 month after LASIK. Near uncorrected visual acuity was significantly better in the combination group than in the artificial tear and diquafosol groups 1 week and 1 month after LASIK. Distance functional visual acuity improved significantly only in the combination group 1 month after LASIK. The Schirmer value in the combination group was significantly higher than that in the hyaluronate group at 1 month after LASIK. Subjective dry eye symptoms in the combination group improved significantly compared with those in the other groups 1 week after surgery. Our results suggest that hyaluronate and diquafosol combination therapy is beneficial for early stabilization of visual performance and improvement of subjective dry eye symptoms in patients after LASIK. Copyright © 2014 Elsevier Inc. All rights reserved.

[Hyperopic Laser-in-situ-Keratomileusis after trifocal intraocular lens implantation : Aberration-free femto-Laser-in-situ-Keratomileusis treatment after implantation of a diffractive, multifocal, toric intraocular lens-case analysis].

PubMed

Hemkeppler, E; Böhm, M; Kohnen, T

2018-05-29

A 52-year-old highly myopic female patient was implanted with a multifocal, diffractive, toric intraocular lens because of the wish to be independent of eyeglasses. Despite high-quality, extensive preoperative examinations, a hyperopic refractive error remained postoperatively, which led to the patient's dissatisfaction. This error was treated with Laser-in-situ-Keratomileusis (LASIK). After corneal LASIK treatment and implantation of a diffractive toric multifocal intraocular lens the patient showed a good postoperative visual result without optical phenomena.

Changes in Keratocyte Density and Visual Function Five Years After Laser In Situ Keratomileusis: Femtosecond Laser Versus Mechanical Microkeratome.

PubMed

McLaren, Jay W; Bourne, William M; Maguire, Leo J; Patel, Sanjay V

2015-07-01

To determine the effects of keratocyte loss on optical properties and vision after laser in situ keratomileusis (LASIK) with the flap created with a femtosecond laser or a mechanical microkeratome. Randomized clinical paired-eye study. Both eyes of 21 patients received LASIK for myopia or myopic astigmatism. One eye of each patient was randomized by ocular dominance to flap creation with a femtosecond laser and the other eye to flap creation with a mechanical microkeratome. Before LASIK and at 1, 3, and 6 months and 1, 3, and 5 years after LASIK, keratocyte density was measured using confocal microscopy, and high-contrast visual acuity and anterior corneal wavefront aberrations were measured by standard methods. At each visit, all variables were compared between methods of creating the flap and to the same variable before treatment using paired tests with Bonferroni correction for multiple comparisons. Keratocyte density in the flap decreased by 20% during the first year after LASIK and remained low through 5 years (P < .001). High-order wavefront aberrations increased and uncorrected visual acuity improved immediately after surgery, but these variables did not change further to 5 years. There were no differences in any variables between treatments. A sustained reduction in keratocyte density does not affect vision or optical properties of the cornea through 5 years after LASIK. The method of creating a LASIK flap does not influence the changes in keratocyte density in the flap. Copyright © 2015 Elsevier Inc. All rights reserved.

Changes in Keratocyte Density and Visual Function Five Years after Laser in situ Keratomileusis: Femtosecond Laser vs Mechanical Microkeratome

PubMed Central

McLaren, Jay W.; Bourne, William M.; Maguire, Leo J.; Patel, Sanjay V.

2015-01-01

Purpose To determine the effects of keratocyte loss on optical properties and vision after laser in situ keratomileusis (LASIK) with the flap created with a femtosecond laser or a mechanical microkeratome. Design Randomized clinical paired-eye study. Methods Both eyes of 21 patients received LASIK for myopia or myopic astigmatism. One eye of each patient was randomized by ocular dominance to flap creation with a femtosecond laser and the other eye to flap creation with a mechanical microkeratome. Before LASIK and at 1, 3, 6 months and 1, 3, and 5 years after LASIK, keratocyte density was measured by using confocal microscopy, and high-contrast visual acuity and anterior corneal wavefront aberrations were measured by standard methods. At each visit, all variables were compared between methods of creating the flap and to the same variable before treatment by using paired tests with Bonferroni correction for multiple comparisons. Results Keratocyte density in the flap decreased by 20% during the first year after LASIK and remained low through 5 years (p<0.001). High-order wavefront aberrations increased and uncorrected visual acuity improved immediately after surgery but these variables did not change further to five years. There were no differences in any variables between treatments. Conclusions A sustained reduction in keratocyte density does not affect vision or optical properties of the cornea through 5 years after LASIK. The method of creating a LASIK flap does not influence the changes in keratocyte density in the flap. PMID:25868758

Assessment of tear osmolarity and other dry eye parameters in post-LASIK eyes.

PubMed

Hassan, Ziad; Szalai, Eszter; Berta, Andras; Modis, Laszlo; Nemeth, Gabor

2013-07-01

To assess the tear osmolarity using the TearLab device after laser in situ keratomileusis (LASIK) and to compare the values with those obtained by traditional tear film tests before and after the procedure. Thirty eyes of 15 refractive surgery candidates (5 men and 10 women of mean age: 30.55 ± 11.79 years) were examined. Using a special questionnaire (Ocular Surface Disease Index), subjective dry eye complaints were evaluated, and then, the tear osmolarity was measured with the TearLab system (TearLab Corporation) and conventional dry eye tests were carried out. Examinations were performed preoperatively and at 1, 30, and 60 days after the surgery. The mean value of tear osmolarity was 303.62 ± 12.29 mOsm/L before the surgery and 303.58 ± 20.14 mOsm/L at 60 days after the treatment (P = 0.69). Mean lid parallel conjunctival folds value was 0.68 ± 0.68 before the procedure and 0.58 ± 0.65 subsequent to surgery (P = 0.25). Meibomian gland dysfunction was not detected. No significant deviation was observed in the values of Schirmer test, corneal staining, tear break-up time, and lid parallel conjunctival folds when compared with postoperatively obtained values during the follow-up period (P > 0.05). During LASIK flap creation, intact corneal innervation is damaged, and the ocular surface lacrimal functional unit can be impaired. In our study, no abnormal dry eye test results were observed before or after the procedure. Based on our results, LASIK treatment is safe for dry eye involving the administration of adequate artificial tears for a minimum of 3 months.

Corneal power, thickness, and stiffness: results of a prospective randomized controlled trial of PRK and LASIK for myopia.

PubMed

Hjortdal, Jesper Ø; Møller-Pedersen, Torben; Ivarsen, Anders; Ehlers, Niels

2005-01-01

To compare the short-, medium-, and long-term changes in corneal optical power and corneal aberrations, central corneal thickness, and corneal "stiffness" assessed by pneumotonometry readings in patients having laser in situ keratomileusis (LASIK) or photorefractive keratectomy (PRK) for myopia. Department of Ophthalmology, Arhus University Hospital, Arhus, Denmark. One eye of each of 45 patients with myopia ranging from -6.00 to -8.00 diopters (D) (spherical equivalent spectacle refraction [SER]) was randomized to LASIK (n=25; mean SER -7.12 D +/- 0.57 [SD]) or PRK (n=20; mean SER -6.91 +/- 0.57 D). Data were collected prospectively before and 1, 3, 6, 12, and 36 months after surgery. Measurements included corneal topography (TMS-1, Tomey), corneal thickness (ultrasound pachymetry), and apparent intraocular pressure (IOP) (pneumotonometry). Retreatments were not performed during the first year, and retreated eyes were excluded from the 3-year follow-up. Changes in corneal power and aberrations, thickness, and apparent IOP were calculated in a pair-wise manner for 3 time periods: short term (preoperative to 1 month after surgery), medium term (1 to 12 months after surgery), and long term (1 to 3 years after surgery). In the short term, corneal power decreased equally in LASIK and PRK eyes. Spherical aberrations and coma-like aberrations increased equally, while corneal thickness decreased significantly less in LASIK eyes than in PRK eyes. The apparent IOP decreased more in LASIK eyes than in PRK eyes. In the medium term, corneal power increased significantly in both groups. Spherical aberrations decreased significantly in PRK eyes but not in LASIK eyes. From 1 to 12 months, corneal thickness increased more in PRK eyes than in LASIK eyes. During this period, the apparent IOP increased significantly in LASIK eyes. In the long term, corneal power and corneal aberrations did not change significantly in either group. Corneal thickness increased slightly but

Laser-Assisted Subepithelial Keratectomy versus Laser In Situ Keratomileusis in Myopia: A Systematic Review and Meta-Analysis

PubMed Central

Zhao, Li-Quan; Zhu, Huang; Li, Liang-Mao

2014-01-01

This systematic review was to compare the clinical outcomes between laser-assisted subepithelial keratectomy (LASEK) and laser in situ keratomileusis (LASIK) for myopia. Primary parameters included mean manifest refraction spherical equivalent (MRSE), MRSE within ±0.50 diopters, uncorrected visual acuity (UCVA) ≥20/20, and loss of ≥1 line of best-corrected visual acuity (BCVA). Secondary parameters included flap complications and corneal haze. Twelve clinical controlled trials were identified and used for comparing LASEK (780 eyes) to LASIK (915 eyes). There were no significant differences in visual and refractive outcomes between the two surgeries for low to moderate myopia. The incidence of loss of ≥1 line of BCVA was significantly higher in moderate to high myopia treated by LASEK than LASIK in the mid-term and long-term followup. The efficacy (MRSE and UCVA) of LASEK appeared to be a significant worsening trend in the long-term followup. Corneal haze was more severe in moderate to high myopia treated by LASEK than LASIK in the mid-term and long-term followup. The flap-related complications still occurred in LASIK, but the incidence was not significantly higher than that in LASEK. LASEK and LASIK were safe and effective for low to moderate myopia. The advantage of LASEK was the absence of flap-related complications, and such procedure complication may occur in LASIK and affect the visual results. The increased incidence of stromal haze and regression in LASEK significantly affected the visual and refractive results for high myopia. PMID:24977054

Corneal collagen crosslinking for corneal ectasia of post-LASIK: one-year results

PubMed Central

Li, Gang; Fan, Zheng-Jun; Peng, Xiu-Jun

2012-01-01

AIM To evaluate the efficacy and safety of corneal collagen crosslinking (CXL) to prevent the progression of post-laser in situ keratomileusis (LASIK) corneal ectasia. METHODS In a prospective, nonrandomized, single-centre study, CXL was performed in 20 eyes of 11 patients who had LASIK for myopic astigmatism and subsequently developed keratectasia.The procedure included instillation of 0.1% riboflavin-20% dextrane solution 30 minutes before UVA irradiation and every 5 minutes for an additional 30 minutes during irradiation. The eyes were evaluated preoperatively and at 1-, 3-, 6-, and 12-month intervals. The complete ophthalmologic examination comprised uncorrected visual acuity, best spectacle-corrected visual acuity, endothelial cell count, ultrasound pachymetry, corneal topography, and in vivo confocal microscopy. RESULTS CXL appeared to stabilise or partially reverse the progression of post-LASIK corneal ectasia without apparent complication in our cohort. UCVA and BCVA improvements were statistically significant(P<0.05) beyond 12 months after surgery (improvement of 0.07 and 0.13 logMAR at 1 year, respectively). Mean baseline flattest meridian keratometry and mean steepest meridian keratometry reduction (improvement of 2.00 and 1.50 diopters(D), respectively) were statistically significant (P<0.05) at 12 months postoperatively. At 1 year after CXL, mean endothelial cell count did not deteriorate. Mean thinnest cornea pachymetry increased significantly. CONCLUSION The results of the study showed a long-term stability of post-LASIK corneal ectasia after crosslinking without relevant side effects. It seems to be a safe and promising procedure to stop the progression of post-LASIK keratectasia, thereby avoiding or delaying keratoplasty. PMID:22762048

Outcomes of photorefractive keratectomy following laser in situ keratomileusis: a cohort study.

PubMed

Iovieno, Alfonso; Teichman, Joshua C; Low, Stephanie; Yeung, Sonia N; Eve Lègarè, Marie; Lichtinger, Alejandro D; Slomovic, Allan R; Rootman, David S

2016-12-01

To analyze the outcomes of photorefractive keratectomy (PRK) on residual myopia and hyperopia post-laser in situ keratomileusis (LASIK) and to compare these results with PRK on eyes without previous laser refractive surgery. Retrospective comparative cohort study. Patients undergoing PRK between 2006 and 2010 were reviewed. Patients were divided into 4 groups, myopic or hyperopic PRK post-LASIK (mPRK-PL and hPRK-PL, respectively) and myopic or hyperopic PRK on corneas without previous laser refractive surgery (mPRK and hPRK, respectively). Uncorrected and corrected distance visual acuity, mean refractive spherical equivalent (MRSE), and mean keratometry and aberrations (total, higher order [HOA], coma, trefoil, and spherical aberration) were recorded at months 3 and 6 postoperatively, as were complications and attempted versus achieved MRSE. Thirty-three eyes of 25 patients who underwent PRK post-LASIK (21 eyes of 14 patients for hPRK-PL and 12 eyes of 11 patients for mPRK-PL) and 35 eyes of 21 patients who underwent PRK on virgin eyes (11 eyes of 8 patients for hPRK and 24 eyes of 13 patients for mPRK) were included in the study. The only significant differences in outcomes were found to be HOA at 3 months for hPRK-PL as compared with both hPRK and mPRK. Achieved MRSE was significantly different from expected MRSE for hPRK-PL at 3 months postoperatively. No haze- or flap-related complications were observed. Outcomes of PRK were not different in myopic and hyperopic corrections post-LASIK by 6 months or when compared with PRK in virgin eyes. HOA may render hPRK-PL results less predictable early in the postoperative period. Copyright © 2016 Canadian Ophthalmological Society. Published by Elsevier Inc. All rights reserved.

Managing residual refractive error after cataract surgery.

PubMed

Sáles, Christopher S; Manche, Edward E

2015-06-01

We present a review of keratorefractive and intraocular approaches to managing residual astigmatic and spherical refractive error after cataract surgery, including laser in situ keratomileusis (LASIK), photorefractive keratectomy (PRK), arcuate keratotomy, intraocular lens (IOL) exchange, piggyback IOLs, and light-adjustable IOLs. Currently available literature suggests that laser vision correction, whether LASIK or PRK, yields more effective and predictable outcomes than intraocular surgery. Piggyback IOLs with a rounded-edge profile implanted in the sulcus may be superior to IOL exchange, but both options present potential risks that likely outweigh the refractive benefits except in cases with large residual spherical errors. The light-adjustable IOL may provide an ideal treatment to pseudophakic ametropia by obviating the need for secondary invasive procedures after cataract surgery, but it is not widely available nor has it been sufficiently studied. Copyright © 2015 ASCRS and ESCRS. Published by Elsevier Inc. All rights reserved.

Activation of Cytomegalovirus corneal endotheliitis following laser in situ keratomileusis.

PubMed

Tan, Tien-En; Cheung, Chui Ming Gemmy; Mehta, Jodhbir S

2016-11-29

A case of Cytomegalovirus (CMV) corneal endotheliitis following laser in-situ keratomileusis (LASIK) is presented. A 32-year-old man presented 3 weeks after uncomplicated myopic LASIK with unilateral LASIK flap oedema, interface fluid accumulation, keratic precipitates, anterior uveitis and raised intraocular pressure. Despite treatment with topical corticosteroids, he had 3 further recurrent episodes. Specular microscopy showed decreased endothelial cell density and aqueous humour. Polymerase chain reaction (PCR) testing was positive for CMV DNA. He was treated with topical ganciclovir and ketorolac, and the inflammation and oedema resolved. Repeat aqueous humour PCR testing was negative for CMV DNA, and he remained well at last follow-up (3 months after stopping all medications). CMV corneal endotheliitis can be reactivated after LASIK, and CMV DNA PCR of aqueous humour samples can help in definitive diagnosis. Early recognition and treatment of this condition is important to prevent permanent endothelial cell loss and corneal decompensation. 2016 BMJ Publishing Group Ltd.

Epipolis-laser in situ keratomileusis versus photorefractive keratectomy for the correction of myopia: a meta-analysis.

PubMed

Wu, Wenjing; Wang, Yan; Xu, Lulu

2015-10-01

It is unclear whether epipolis-laser in situ keratomileusis (Epi-LASIK) has any significant advantage over photorefractive keratectomy (PRK) for correcting myopia. We undertook this meta-analysis of randomized controlled trials and cohort studies to examine possible differences in efficacy, predictability, and side effects between Epi-LASIK and PRK for correcting myopia. A system literature review was conducted in the PubMed, Cochrane Library EMBASE. The statistical analysis was performed by RevMan 5.0 software. The results included efficacy outcomes (percentage of eyes with 20/20 uncorrected visual acuity post-treatment), predictability (proportion of eyes within ±0.5 D of the target refraction), epithelial healing time, and the incidence of significant haze and pain scores after surgery. There are seven articles with total 987 eyes suitable for the meta-analysis. There is no statistical significance in the predictability between Epi-LASIK and PRK, the risk ratio (RR) is 1.03, 95% confidence interval (CI) [0.92, 1.16], p = 0.18; with respect to efficacy, the odds ratio is 1.43, 95% CI = [0.85, 2.40], p = 0.56 between Epi-LASIK and PRK, there is no statistical significance either. The epithelial cell layer healing time and the pain scores and the incidence of significant haze showed no significance between these two techniques although more pains can be found in Epi-LASIK than PRK at the early-stage post-operation. According to the above analysis, Epi-LASIK has good efficacy and predictability as PRK. In addition, both techniques have low pain scores and low incidence of significant haze.

Clinical results of the laser-assisted in situ keratomileusis (LASIK) for myopia

NASA Astrophysics Data System (ADS)

Guo, Hai-ke; Yao, Da-qing; Gui, Lu-ping

1998-11-01

To observe and analyze the refractive and complications of the LASIK for corrections of myopia. With the microlamellar keratoplasty and the excimer laser, LASIK was performed on 194 cases. According to the preoperative spherical equivalent refraction, divide the patients into three groups.

[Comparison of the anterior corneal asphericity after small incision lenticule extraction and femtosecond laser in situ keratomileusis].

PubMed

Su, X L; Wang, Y; Wu, W J; Wu, Z Q; Wu, Y N; Yu, C J

2016-09-11

To evaluate and compare the anterior corneal asphericity after small incision lenticule extraction(SMILE)and femtosecond laser in situ keratomileusis(FS-LASIK). In this case-control study, 45 subjects who underwent SMILE operation comprised the study group, and 33 subjects with FS-LASIK operation comprised the control group. The asphericity coefficient Q-value of the right eyes in both groups was measured at diameters of 6, 7, 8 and 9 mm, respectively, before surgery and at 1 day, 1 week, 1 month and 6 months following surgery. The correlation between the variation of Q-value and the central cutting depth was analyzed. The Q-value of anterior corneal surface was 0.85 ± 0.31, 0.80±0.28, 0.69±0.25 and 0.51±0.23 after SMILE, and 1.13±0.56, 1.01±0.47, 0.80±0.39 and 0.51±0.31 after FS-LASIK at 1 week. In both groups, the Q-value was significantly different before and after surgery(P< 0.05); there were interaction effects between the operation method and time; the difference between the two groups at 6-mm and 7-mm diameters was statistically significant(P<0.05). The variation of the Q-value before and after operation(ΔQ)showed significant difference(P6mm=0.004, P7mm=0.014)between the two groups at 6-mm and 7-mm diameters. The cap diameter of the SMILE group was smaller than that of the FS-LASIK group, but the cutting depth was larger. There was no correlation between ΔQ and the cap/disc diameter. It showed a linear relationship(P<0.05)between ΔQ and the central cutting depth at all examined diameters in the two groups, and the relation degree in the FS-LASIK group was superior to the SMILE group. Both SMILE and FS-LASIK operations can change the negative Q-value of the anterior corneal surface to the positive. The impact of SMILE on the asphericity is smaller than that of FS-LASIK. (Chin J Ophthalmol, 2016, 52: 681-685).

Aircrew Performance Cutting-Edge Technology: Emerging Human Performance Enhancement Technology Vision in Support of Operational Military Aviation Strategy

DTIC Science & Technology

2003-09-01

Refractive Surgery Origin and History, (RK, PRK , LASIK ) Refractive surgery was first considered as early as 1898 by a Dutch professor and was...34 This ejection demonstrated one extreme facet of the safety of PRK . Laser-Assisted In Situ Keratomileusis ( LASIK ) LASIK offers the greatest...refractive shift of clinical significance.35 Therefore LASIK and PRK , recipients had no significant vision changes at altitude, unlike recipients of RK

Femtosecond-LASIK outcomes using the VisuMax®-MEL® 80 platform for mixed astigmatism refractive surgery.

PubMed

Stanca, Horia Tudor; Munteanu, Mihnea; Jianu, Dragoş Cătălin; Motoc, Andrei Gheorghe Marius; Jecan, Cristian Radu; Tăbăcaru, Bogdana; Stanca, Simona; Preda, Maria Alexandra

2018-01-01

To evaluate the predictability, efficacy and safety of Femtosecond-laser-assisted in situ keratomileusis (LASIK) procedure for mixed astigmatism. We prospectively evaluated for 12 months 74 eyes (52 patients) with mixed astigmatism that underwent Femtosecond-LASIK treatment. The preoperative mean refractive sphere value was +1.879±1.313 diopters (D) and the mean refractive cylinder value was -4.169±1.091 D. The anterior corneal flap was cut using the VisuMax® femtosecond laser and then the stromal ablation was done using the MEL® 80 excimer laser. Mean age was 30.22±6.421 years with 61.53% female patients. Postoperative spherical equivalent at 12 months was within ±0.5D of emmetropia in 75.8% of eyes and within ±1D in 97.3% of eyes. Postoperative uncorrected distance visual acuity was equivalent to or better than the preoperative corrected distance visual acuity in 91.9% of eyes. Compared to the preoperative corrected distance visual acuity (CDVA), 8.1% of eyes gained one line, 2.7% gained two lines and 2.7% gained three lines of visual acuity. Femtosecond-LASIK using the VisuMax®-MEL® 80 platform appears to have safe, effective and predictable results in mixed astigmatic eyes. The results are impressive for high refractive error treatment and for improvement of both uncorrected and corrected distance visual acuity.

Dry Eye Post-Laser-Assisted In Situ Keratomileusis: Major Review and Latest Updates

PubMed Central

Spierer, Oriel

2018-01-01

Dry eye is one of the most common complications occurring after laser-assisted in situ keratomileusis (LASIK), with virtually all patients experiencing some degree of postoperative dry eye symptoms. Enhanced understanding of the pathophysiology and mechanism of dry eye development in addition to preoperative screening of patients who are prone to dry eye is essential for better patient satisfaction and for improving short-term visual outcome postoperatively. This article reviews the latest studies published on LASIK-associated dry eye, including epidemiology, pathophysiology, risk factors, preoperative assessment, and management. PMID:29619255

Ocular residual astigmatism's effect on high myopic astigmatism LASIK surgery

PubMed Central

Teus, M A; Arruabarrena, C; Hernández-Verdejo, J L; Cañones, R; Mikropoulos, D G

2014-01-01

Purpose To analyze the effect of ocular residual astigmatism (ORA) on the effectiveness of LASIK for treating high myopic astigmatism. Methods This is an observational, cross-sectional study. We studied 116 consecutive myopic eyes with −3 diopters (D) or more of astigmatism that underwent LASIK surgery. The magnitude of uncorrected residual refractive astigmatism 3 months postoperatively was measured. Results The mean preoperative cylinder was −4.0±0.83 D (range, −7.5 to −3 D) and the mean preoperative ORA was 0.82±0.5 D. The mean residual refractive cylinder 3 months postoperatively was −0.78±0.83 D (range, −3 to 0 D). No correlation was found between ORA and the refractive cylinder 3 months postoperatively (P=0.6). Conclusion In eyes with high myopic astigmatism undergoing LASIK, ORA was not correlated with the residual postoperative cylinder. PMID:24971989

Review of Efforts to Develop a Low-Luminance-Level Disability Glare Tester

DTIC Science & Technology

2009-09-01

figures 1. LASIK and PRK refractive surgery. .......................................................................................... 6  2...inadequate at this time, particularly for post refractive surgery patients. Early LASIK and PRK produced a very high incidence of night vision...1999). They found that before PRK or LASER in-situ keratomileusis ( LASIK ), simulated pupil dilation from 3 to 7 mm caused a 5-6 fold increase in

Retinal nerve fiber layer changes after LASIK evaluated with optical coherence tomography.

PubMed

Dementyev, Dmitriy D; Kourenkov, Vyacheslav V; Rodin, Alexander S; Fadeykina, Tatyana L; Diaz Martines, Tatyana E

2005-01-01

To determine whether the increase in intraocular pressure (IOP) during LASIK suction can induce a decrease in retinal nerve fiber layer thickness assessed by optical coherence tomography (OCT). Nineteen patients (38 eyes) were enrolled in the study. Intraocular pressure was normal at all pre- and postoperative examinations. Retinal nerve fiber layer thickness was measured using OCT-3 Stratus prior to and 1 week and 3 months after LASIK. Laser in situ keratomileusis was performed using the Bausch & Lomb Hansatome microkeratome and the NIDEK EC-5000 excimer laser. Optical coherence tomography mean retinal nerve fiber layer thickness values before and after LASIK were compared using the Student paired t test. Mean patient age was 27.8 years (range: 18 to 33 years). Mean preoperative spherical equivalent refractive error was -4.9 diopters (D) (range: -2.0 to -8.5 D). Mean time of microkeratome suction was 30 seconds (range: 20 to 50 seconds). Preoperatively, the mean retinal nerve fiber layer thickness obtained by OCT was 104.2+/-9.0 microm; at 1 week postoperatively the mean thickness was 101.9+/-6.9 microm, and 106.7+/-6.1 microm at 3 months postoperatively. Mean retinal nerve fiber layer thicknesses obtained by OCT were not significantly different between preoperative and 1 week and 3 months after LASIK (P > or = .05). Laser in situ keratomileusis performed on young myopic patients does not have a significant effect on retinal nerve fiber layer thickness determined by OCT. Further studies are required to reveal the risk of possible optic nerve or retinal nerve fiber layer damage by elevated IOP during LASIK.

A prospective, contralateral eye study comparing thin-flap LASIK (sub-Bowman keratomileusis) with photorefractive keratectomy.

PubMed

Slade, Stephen G; Durrie, Daniel S; Binder, Perry S

2009-06-01

To determine the differences in the visual results, pain response, biomechanical effect, quality of vision, and higher-order aberrations, among other parameters, in eyes undergoing either photorefractive keratectomy (PRK) or thin-flap LASIK/sub-Bowman keratomileusis (SBK; intended flap thickness of +/-100 microm and 8.5-mm diameter) at 1, 3, and 6 months after surgery. A contralateral eye pilot study. Fifty patients (100 eyes) were enrolled at 2 sites. The mean preoperative spherical refraction was -3.66 diopters (D) and the mean cylinder was -0.66 D for all eyes. Eyes in the PRK group underwent 8.5-mm ethanol-assisted PRK, whereas in eyes in the SBK group, an 8.5-mm, (intended) 100-microm flap was created with a 60-kHz IntraLase femtosecond laser (Advanced Medical Optics, Santa Ana, CA). All eyes underwent a customized laser ablation using an Alcon LADARVision 4000 CustomCornea excimer laser (Alcon Laboratories, Fort Worth, TX). Preoperative and postoperative tests included best spectacle-corrected visual acuity, uncorrected visual acuity (UCVA), corneal topography, wavefront aberrometry, retinal image quality, and contrast sensitivity. Patients completed subjective questionnaires at each visit. One- and 3-month UCVA results showed a statistically significant difference: SBK, 88% 20/20 or better vs. 48% 20/20 or better for PRK. At 6 months, UCVA was 94% 20/20 or better for PRK and 92% for SBK. At 1 and 3 months, the SBK group had lower higher-order aberrations (coma and spherical aberration; P

Retinal Detachment After Laser In Situ Keratomileusis

PubMed Central

Al-Rashaed, Saba; Al-Halafi, Ali M

2011-01-01

Purpose: To report characteristics and outcome of rhegmatogenous retinal detachment (RRD) after laser in situ keratomileusis (LASIK) for myopia. Materials and Methods: A retrospective chart review of patients who presented with RRD after myopic LASIK over a 10-year period. Results: Fourteen eyes were identified with RRD. Of these, two of 6112 LASIK procedures were from our center. The mean age of patients with RRD was 35.43 years. The mean interval of RRD after LASIK was 37.71 months (range, 4 months to 10 years). The macula was involved in eight eyes and spared in six eyes. Retinal breaks included a macular hole in two eyes, and giant tear in two eyes. Multiple breaks (>2 breaks) occurred in 6 cases. Pars plana vitrectomy (PPV) was performed in 3 (21.4%) eyes, a scleral buckle (SB) was performed in 4 (28.5%) eyes and 7 (50%) eyes underwent combined PPV and SB. Mean follow-up was 15.18 months (range, 1 month to 7 years). The retina was successfully attached in all cases. The final visual acuity was 20/40 or better in 7 (50%) eyes, 20/40 to 20/60 in 4 (28.5%) eyes, and 20/200 or less in 3 (21.4%) eyes. Poor visual outcome was secondary to proliferative vitreoretinopathy, epiretinal membrane, macular scar and amblyopia. Conclusion: The prevalence of RRD after LASIK was low at our institute. Anatomical and visual outcomes were acceptable in eyes that were managed promptly. Although there is no cause-effect relationship between LASIK and RRD, a dilated fundus examination is highly recommended before and after LASIK for myopia. PMID:21887078

Three-year results of small incision lenticule extraction and wavefront-guided femtosecond laser-assisted laser in situ keratomileusis for correction of high myopia and myopic astigmatism.

PubMed

Xia, Li-Kun; Ma, Jing; Liu, He-Nan; Shi, Ce; Huang, Qing

2018-01-01

To compare and calculate the 3-year refractive results, higher-order aberrations (HOAs), contrast sensitivity (CS) and dry eye parameters after small incision lenticule extraction (SMILE) and wavefront-guided femtosecond laser-assisted laser in situ keratomileusis (FS-LASIK) for correction of high myopia and myopic astigmatism. In this prospective, non-randomized comparative study, 78 eyes with spherical equivalent (SE) of -8.11±1.09 diopters (D) received a SMILE surgery, and 65 eyes with SE of -8.05±1.12 D received a wavefront-guided FS-LASIK surgery with the VisuMax femtosecond laser (Carl Zeiss Meditec, Jena, Germany) for flap cutting. Visual acuity, manifest refraction, CS, HOAs, ocular surface disease index (OSDI) and tear break-up time (TBUT) were evaluated during a 3-year follow-up. The difference of uncorrected distance visual acuity (UDVA) postoperatively was achieved at 1mo and at 3mo, whereas the difference of the mean UDVA between two groups at 3y were not statistically significant ( t =-1.59, P =0.13). The postoperative change of SE was 0.89 D in the FS-LASIK group ( t =5.76, P =0.00), and 0.14 D in the SMILE group ( t =0.54, P =0.59) from 1mo to 3y after surgery. At 3-year postoperatively, both HOAs and spherical aberrations in the SMILE group were obviously less than those in the FS-LASIK group ( P =0.00), but the coma root mean square (RMS) was higher in the SMILE group (0.59±0.26) than in the FS-LASIK group (0.29±0.14, P =0.00). The mesopic CS values between two groups were not statistically significant at 3y postoperatively. Compared with the FS-LASIK group, lower OSDI scores and longer TBUT values were found in the SMILE group at 1mo and 3mo postoperatively. With regard to safety, no eye lost any line of CDVA in both groups at 3y after surgery. Both SMILE and wavefront-guided FS-LASIK procedures provide good visual outcomes. Both procedures are effective and safe, but SMILE surgery achieve more stable long-term refractive outcome and better

[Clinical Results of Diffractive Multifocal Intraocular Lens Implantation after Laser In Situ Keratomileusis].

PubMed

Yoshino, Mami; Minami, Keiichiro; Hirasawa, Manabu; Oki, Shinichi; Bissen-Miyajima, Hiroko

2015-09-01

To evaluate the visual performance in eyes with diffractive intraocular lenses (IOLs) after laser in situ keratomileusis (LASIK). This single-center retrospective study evaluated eyes that had diffractive multifocal IOL implantation after previous LASIK or not treated with LASIK (controls). The outcomes' measures were the visual acuities (VAs) at distance and near, spherical equivalent (SE) and contrast sensitivity at one month postoperatively. The study evaluated 40 eyes of 33 patients. The mean uncorrected logMAR VAs were -0.05 ± 0.13/0.00 ± 0.14 (LASIK group/control group) at distance and 0.10 ± 0.13/0.16 ± 0.18 at near. There was no statistically significant difference between the 2 groups at the VAs. The SE of the LASIK group was -0.06 ± 0.39 D, significantly lower than the control group (0.22 ± 0.45 D) (p < 0.05). The contrast sensitivity of the LASIK group at high spatial frequency was lower than the control group (p < 0.05). After LASIK, the diffractive multifocal IOL provided good uncorrected distance and near VAs. However, decrease in contrast sensitivity should be considered.

Increased preference of surface ablation over laser in situ keratomileusis between 2008–2011 is correlated to risk of ecatasia

PubMed Central

Moisseiev, Elad; Sela, Tzahi; Minkev, Liza; Varssano, David

2013-01-01

Purpose To evaluate the trends in corneal refractive procedure selection for the correction of myopia, focusing on the relative proportions of laser in situ keratomileusis (LASIK) and surface ablation procedures. Methods Only eyes that underwent LASIK or surface ablation for the correction of myopia between 2008–2011 were included in this retrospective study. Additional recorded parameters included patient age, preoperative manifest refraction, corneal thickness, and calculated residual corneal bed thickness. A risk score was given to each eye, based on these parameters, according to the Ectasia Risk Factor Score System (ERFSS), without the preoperative corneal topography. Results This study included 16,163 eyes, of which 38.4% underwent LASIK and 61.6% underwent surface ablation. The risk score correlated with procedure selection, with LASIK being preferred in eyes with a score of 0 and surface ablation in eyes with a score of 2 or higher. When controlling for age, preoperative manifest refraction, corneal thickness, and all parameters, the relative proportion of surface ablation compared with LASIK was found to have grown significantly during the study period. Conclusions Our results indicate that with time, surface ablation tended to be performed more often than LASIK for the correction of myopia in our cohort. Increased awareness of risk factors and preoperative risk assessment tools, such as the ERFSS, have shifted the current practice of refractive surgery from LASIK towards surface ablation despite the former’s advantages, especially in cases in which the risk for ectasia is more than minimal (risk score 2 and higher). PMID:23345963

Effects of ablation depth and repair time on the corneal elastic modulus after laser in situ keratomileusis.

PubMed

Wang, Xiaojun; Li, Xiaona; Chen, Weiyi; He, Rui; Gao, Zhipeng; Feng, Pengfei

2017-01-17

The biomechanical properties of the cornea should be taken into account in the refractive procedure in order to perform refractive surgery more accurately. The effects of the ablation depth and repair time on the elastic modulus of the rabbit cornea after laser in situ keratomileusis (LASIK) are still unclear. In this study, LASIK was performed on New Zealand rabbits with different ablation depth (only typical LASIK flaps were created; residual stroma bed was 50 or 30% of the whole cornea thickness respectively). The animals without any treatment were served as normal controls. The corneal thickness was measured by ultrasonic pachymetry before animals were humanly killed after 7 or 28 days post-operatively. The corneal elastic modulus was measured by uniaxial tensile testing. A mathematical procedure considering the actual geometrics of the cornea was created to analyze the corneal elastic modulus. There were no obvious differences among all groups in the elastic modulus on after 7 days post-operatively. However, after 28th days post-operatively, there was a significant increase in the elastic modulus with 50 and 30% residual stroma bed; only the elastic modulus of the cornea with 30% residual stroma bed was significantly higher than that of 7 days. Changes in elastic modulus after LASIK suggest that this biomechanical effect may correlate with the ablation depth and repair time.

Outcomes of LASIK and PRK in previous penetrating corneal transplant recipients.

PubMed

Kovoor, Timmy A; Mohamed, Engy; Cavanagh, H Dwight; Bowman, R Wayne

2009-09-01

To evaluate the safety and efficacy of excimer laser refractive surgery in correcting refractive error in eyes that have undergone previous penetrating keratoplasty (PK). Twenty-three keratorefractive procedures on 16 eyes from 16 consecutive subjects were evaluated between 2002 and 2008. Each patient presented a previous history of a PK with subsequent postoperative myopia and astigmatism. Keratometric value, manifest refraction, best-corrected visual acuity, uncorrected visual acuity, and complications were determined. There were a total of 14 photorefractive keratectomy (PRK) procedures performed on 11 eyes and 9 laser in situ keratomileusis (LASIK) procedures performed on 5 eyes. In the PRK group, the preoperative post-PK manifest refractive spherical equivalent and cylindrical error were -6.22 +/- 6.23 diopter and 5.23 +/- 2.26 D, respectively. The PRK postoperative manifest refractive spherical equivalent and cylindrical error were -3.61 +/- 4.23 D (P=0.25) and 3.21 +/- 1.78 D (P=0.02), respectively. In the LASIK group, the preoperative post-PK manifest refractive spherical equivalent and cylindrical error were -3.05 +/- 3.29 D and 4.11 +/- 2.38 D, respectively. The LASIK postoperative manifest refractive spherical equivalent and cylindrical error were -1.51 +/- 2.02 D (P=0.24) and 2.08 +/- 1.26 D (P=0.03), respectively. There was a 2-line or greater improvement of uncorrected visual acuity in 8 of the 14 PRK treatments and 5 of the 9 LASIK treatments. There were two episodes of acute graft rejection. One of the episodes resolved with topical and oral corticosteroids, and the other episode required a repeat corneal transplantation. PRK and LASIK are effective tools in reducing surgically induced astigmatism after penetrating corneal transplantation in most patients in this case series. The reduction of astigmatism may allow improved contact lens or spectacle fitting to achieve best-corrected binocular visual acuity.

Influence of the difference between corneal and refractive astigmatism on LASIK outcomes using solid-state technology.

PubMed

Piñero, David P; Ribera, David; Pérez-Cambrodí, Rafael J; Ruiz-Fortes, Pedro; Blanes-Mompó, Francisco J; Alzamora-Rodríguez, Antonio; Artola, Alberto

2014-12-01

To evaluate the influence of the difference between preoperative corneal and refractive astigmatism [ocular residual astigmatism (ORA)] on outcomes obtained after laser in situ keratomileusis (LASIK) surgery for correction of myopic astigmatism using the solid-state laser technology. One hundred one consecutive eyes with myopia or myopic astigmatism of 55 patients undergoing LASIK surgery using the Pulzar Z1 solid-state laser (CustomVis Laser Pty Ltd, currently CV Laser) were included. Visual and refractive changes at 6 months postoperatively and changes in ORA and anterior corneal astigmatism and posterior corneal astigmatism (PCA) were analyzed. Postoperatively, uncorrected distance visual acuity improved significantly (P < 0.01). Likewise, refractive cylinder magnitude and spherical equivalent were reduced significantly (P < 0.01). In contrast, no significant changes were observed in ORA magnitude (P = 0.81) and anterior corneal astigmatism (P = 0.12). The mean overall efficacy and safety indices were 0.96 and 1.01, respectively. These indices were not correlated with preoperative ORA (r = -0.15, P = 0.15). Furthermore, a significant correlation was found between ORA (r = 0.81, P < 0.01) and PCA postoperatively, but not preoperatively (r = 0.12, P = 0.25). Likewise, a significant correlation of ORA with manifest refraction was only found postoperatively (r = -0.38, P < 0.01). The magnitude of ORA does not seem to be a predictive factor of efficacy and safety of myopic LASIK using a solid-state laser platform. The higher relevance of PCA after surgery in some cases may explain the presence of unexpected astigmatic residual refractive errors.

Clinical outcomes of small incision lenticule extraction versus femtosecond laser-assisted LASIK for myopia: a Meta-analysis

PubMed Central

Yan, Huan; Gong, Li-Yan; Huang, Wei; Peng, Yan-Li

2017-01-01

AIM To evaluate the possible differences in visual quality between small incision lenticule extraction (SMILE) and femtosecond laser in situ keratomileusis (FS-LASIK) for myopia. METHODS A Meta-analysis was performed. Patients were from previously reported comparative studies treated with SMILE versus FS-LASIK. The PubMed, EMBASE, Cochrane, Web of Science and Chinese databases (i.e. WANFANG and CNKI) were searched in Nov. of 2016 using RevMan 5.1 version software. The differences in visual acuity, aberration and biomechanical effects within six months postoperatively were showed. Twenty-seven studies including 4223 eyes were included. RESULTS No significant differences were observed between SMILE and FS-LASIK in terms of the proportion of eyes that lost one or more lines of corrected distance visual acuity after surgery (P=0.14), the proportion of eyes achieving an uncorrected distance visual acuity of 20/20 or better (P=0.43), the final refractive spherical equivalent (P=0.89), the refractive spherical equivalent within ±1.00 diopter of the target values (P=0.80), vertical coma (P=0.45) and horizontal coma (P=0.06). Compared with the FS-LASIK group, total higher-order aberration (P<0.001) and spherical aberration (P<0.001) were higher and the decrease in corneal hysteresis (P=0.0005) and corneal resistance factor (P=0.02) were lower in the SMILE group. CONCLUSION SMILE and FS-LASIK are comparable in efficacy, safety and predictability for correcting myopia. However, the aberration in the SMILE group is superior to that in the FS-LASIK group, and the loss of biomechanical effects may occur less frequently after SMILE than after FS-LASIK. PMID:28944205

Laser-assisted in situ keratomileusis with optimized, fast-repetition, and cyclotorsion control excimer laser to treat hyperopic astigmatism with high cylinder.

PubMed

Alió Del Barrio, Jorge L; Tiveron, Mauro; Plaza-Puche, Ana B; Amesty, María A; Casanova, Laura; García, María J; Alió, Jorge L

2017-10-18

To evaluate the visual outcomes after femtosecond laser-assisted laser in situ keratomileusis (LASIK) surgery to correct primary compound hyperopic astigmatism with high cylinder using a fast repetition rate excimer laser platform with optimized aspheric profiles and cyclotorsion control. Eyes with primary simple or compound hyperopic astigmatism and a cylinder power ≥3.00 D had uneventful femtosecond laser-assisted LASIK with a fast repetition rate excimer laser ablation, aspheric profiles, and cyclotorsion control. Visual, refractive, and aberrometric results were evaluated at the 3- and 6-month follow-up. The astigmatic outcome was evaluated using the Alpins method and ASSORT software. This study enrolled 80 eyes at 3 months and 50 eyes at 6 months. The significant reduction in refractive sphere and cylinder 3 and 6 months postoperatively (p<0.01) was associated with an improved uncorrected distance visual acuity (p<0.01). A total of 23.75% required retreatment 3 months after surgery. Efficacy and safety indices at 6 months were 0.90 and 1.00, respectively. At 6 months, 80% of eyes had an SE within ±0.50 D and 96% within ±1.00 D. No significant differences were detected between the third and the sixth postoperative months in refractive parameters. A significant increase in the spherical aberration was detected, but not in coma. The correction index was 0.94 at 3 months. Laser in situ keratomileusis for primary compound hyperopic astigmatism with high cylinder (>3.00 D) using the latest excimer platforms with cyclotorsion control, fast repetition rate, and optimized aspheric profiles is safe, moderately effective, and predictable.

Effect of insulin-like growth factor-1 on corneal surface ultrastructure and nerve regeneration of rabbit eyes after laser in situ keratomileusis.

PubMed

Wang, Chunyan; Peng, Yanli; Pan, Shuling; Li, Li

2014-01-13

To explore the effect of insulin-like growth factor-1 (IGF-1) on corneal surface ultrastructure and nerve regeneration in rabbit models after laser in situ keratomileusis (LASIK). Forty-two healthy New Zealand white rabbits were divided into two groups, the IGF-1 group and the control group, and LASIK surgery was performed. The corneal surface ultrastructure was observed by transmission electron microscopy, and the nerve regeneration was evaluated by counting the newly regenerated nerves at 1 d, 1 w, 2 w, 1 m, 3 m and 6 m after surgery. Dry eye parameters, including the Schirmer I test and tear break-up time, were examined at all time points. The examination of corneal ultrastructure showed that the number of corneal epithelial microvilli in the IGF-1 group was significantly higher than that in the normal saline (NS) group except in the second postoperative week (p<0.05). The observation of corneal nerve regeneration showed that the number of regenerated nerve fibers in the IGF-1 group was higher than the control group at all time points (p<0.05). The parameters of dry eye were significantly higher in the IGF-1 group compared to the control group at all time points except at 1d and 6m after LASIK. IGF-1 can effectively accelerate the early repair of corneal surface ultrastructure and nerve regeneration after LASIK and relieve dry eye symptoms in rabbit eyes. Copyright © 2013 Elsevier Ireland Ltd. All rights reserved.

Tear menisci after laser in situ keratomileusis with mechanical microkeratome and femtosecond laser.

PubMed

Xie, Wenjia; Zhang, Dong; Chen, Jia; Liu, Jing; Yu, Ye; Hu, Liang

2014-08-21

To investigate the effect on tear menisci after laser in situ keratomileusis (LASIK) with flap creation by either microkeratome or femtosecond laser. Sixty eyes of 30 myopes were analyzed. Fifteen patients underwent LASIK with Moria II microkeratome, and the other 15 patients with 60-KHz IntraLase femtosecond laser. Upper and lower tear meniscus parameters of height (UTMH, LTMH) and area (UTMA, LTMA) were measured by SD-OCT preoperatively and 1 week, 1 month, and 3 months postoperatively. Compared with the baseline values, all tear meniscus parameters decreased significantly at each postoperative time point (all P < 0.01) in both groups. LTMH increased significantly between 1 week and 1 month and between 1 and 3 months after surgery in the microkeratome (both P < 0.01) and femtosecond laser groups (P < 0.01, P = 0.012, respectively). There were significant increases in LTMA between 1 week and 1 month after surgery in the microkeratome group (P < 0.01) and in the femtosecond laser group (P = 0.028). There were no significant differences in UTMH, UTMA, LTMH, or LTMA between two groups. The depth of ablation was negatively correlated with the LTMA at 1 week after surgery (R = -0.256, P = 0.049) for all patients. There were no significant differences in the tear meniscus parameters between the microkeratome and femtosecond laser groups. The depth of ablation was significantly correlated with the LTMA only at 1 week after surgery. Copyright 2014 The Association for Research in Vision and Ophthalmology, Inc.

Symptoms and Satisfaction of Patients in the Patient-Reported Outcomes With Laser In Situ Keratomileusis (PROWL) Studies.

PubMed

Eydelman, Malvina; Hilmantel, Gene; Tarver, Michelle E; Hofmeister, Elizabeth M; May, Jeanine; Hammel, Keri; Hays, Ron D; Ferris, Frederick

2017-01-01

Patient-reported outcomes should be collected using validated questionnaires prior to and following laser in situ keratomileusis (LASIK) surgery. To report the frequency of patient-reported visual symptoms, dry eye symptoms, satisfaction with vision, and satisfaction with LASIK surgery in the Patient-Reported Outcomes With LASIK (PROWL) studies. The PROWL-1 and PROWL-2 studies were prospective, observational studies conducted from September 13, 2011, to June 27, 2014. The PROWL-1 study was a single-military center study of 262 active-duty Navy personnel 21 to 52 years of age. The PROWL-2 study was a study of 312 civilians 21 to 57 years of age conducted at 5 private practice and academic centers. The LASIK surgery and the postoperative care were performed based on the usual practice and clinical judgment at the site. Participants completed a self-administered, web-based questionnaire, preoperatively and postoperatively at 1 and 3 months (the PROWL-1 and -2 studies) and at 6 months (the PROWL-2 study). Participants underwent LASIK surgery for myopia, hyperopia, and/or astigmatism. Visual symptoms (double images, glare, halos, and/or starbursts), dry eye symptoms, participant satisfaction (with vision and LASIK surgery), and clinical measures (visual acuity, refractive error, and slitlamp and posterior segment eye examination findings) were assessed preoperatively and at 1, 3, and 6 months postoperatively. A total of 262 participants were enrolled in the PROWL-1 study (mean [SD] age, 29.1 [6.1] years), and a total of 312 participants were enrolled in the PROWL-2 study (mean [SD] age, 31.5 [7.3] years). Visual symptoms and dissatisfaction with vision were common preoperatively. Overall, the prevalence of visual symptoms and dry eye symptoms decreased, although a substantial percentage of participants reported new visual symptoms after surgery (43% [95% CI, 31%-55%] from the PROWL-1 study and 46% [95% CI, 33%-58%] from the PROWL-2 study at 3 months). The percentages of

Femtosecond (FS) laser vision correction procedure for moderate to high myopia: a prospective study of ReLEx(®) flex and comparison with a retrospective study of FS-laser in situ keratomileusis.

PubMed

Vestergaard, Anders; Ivarsen, Anders; Asp, Sven; Hjortdal, Jesper Ø

2013-06-01

To present our initial clinical experience with ReLEx(®) flex (ReLEx) for moderate to high myopia. We compare efficacy, safety and corneal higher-order aberrations after ReLEx with femtosecond laser in situ keratomileusis (FS-LASIK). Prospective study of ReLEx compared with a retrospective study of FS-LASIK. ReLEx is a new keratorefractive procedure, where a stromal lenticule is cut by a femtosecond laser and manually extracted. Forty patients were treated with ReLEx on both eyes. A comparable group of 41 FS-LASIK patients were retrospectively identified. Visual acuity, spherical equivalent (SE) and corneal tomography were measured before and 3 months after surgery. Preoperative SE averaged -7.50 ± 1.16 D (ReLEx) and -7.32 ± 1.09 D (FS-LASIK). For all eyes, mean corrected distance visual acuity remained unchanged in both groups. For eyes with emmetropia as target refraction, 41% of ReLEx and 61% of FS-LASIK eyes had an uncorrected distance visual acuity of logMAR ≤ 0.10 at day 1 after surgery, increasing to, respectively, 88% and 69% at 3 months. Mean SE was -0.06 ± 0.35 D 3 months after ReLEx and -0.53 ± 0.60 D after FS-LASIK. The proportion of eyes within ±1.00 D after 3 months was 100% (ReLEx) and 85% (FS-LASIK). For a 6.0-mm pupil, corneal spherical aberrations increased significantly less in ReLEx than FS-LASIK eyes. ReLEx is an all-in-one femtosecond laser refractive procedure, and in this study, results were comparable to FS-LASIK. Refractive predictability and corneal aberrations at 3 months seemed better than or equal to FS-LASIK, whereas visual recovery after ReLEx was slower. © 2012 The Authors. Acta Ophthalmologica © 2012 Acta Ophthalmologica Scandinavica Foundation.

Evaluation of the Orssengo-Pye IOP corrective algorithm in LASIK patients with thick corneas.

PubMed

Kirstein, Elliot M; Hüsler, André

2005-09-01

The objective of this study was to evaluate the Orssengo-Pye central corneal thickness (CCT) Goldmann applanation tonometry (GAT) corrective algorithm by observing changes in GAT and CCT before and after laser in situ keratomileusis (LASIK) surgery in patients with CCT that remains greater than 545 microm postoperatively. Tonometric and pachymetric measurements were made on 14 patients (28 eyes) before and after LASIK surgery. The selected patients were required to have average or above average postoperative central corneal thickness values in both eyes (not less than 545 microm). Preoperatively, all patients had CCT and GAT measurements taken. Postoperatively patients had CCT, GAT, and dynamic contour tonometric (DCT) measurements taken. Preoperatively, median CCT values were 589.536 microm. Median GAT values were 16.750 mmHg. Median corrected preoperative GAT values were 14.450 mmHg. After LASIK treatment, median CCT values were 559.417 microm. The decrease in median CCT was 30.119 microm. Median postoperative GAT values were 11.500 mmHg (decrease, 5.250 mmHg). Median corrected postoperative GAT values were 10.775 mmHg (decrease, 3.675 mmHg). Median postoperative DCT values were 17.858 mmHg. LASIK treatment causes a significant reduction in measured GAT intraocular pressure (IOP) values. The Orssengo-Pye formula, which attempts to correct for GAT error associated with individual variation in CCT, appears to yield misleading results in these circumstances. An unexpected 3.675-mmHg decrease in "corrected IOP" by the Orssengo-Pye method seen in this study may be attributed to some limitation or error in the formula. After adjusting for the approximate1.7-mmHg difference, which has been demonstrated between DCT and GAT, postoperative DCT values were similar to preoperative measured GAT values.

Laser in-situ keratomileusis for refractive error following radial keratotomy

PubMed Central

Sinha, Rajesh; Sharma, Namrata; Ahuja, Rakesh; Kumar, Chandrashekhar; Vajpayee, Rasik B

2011-01-01

Aim: To evaluate the safety and efficacy of laser in-situ keratomileusis (LASIK) in eyes with residual/induced refractive error following radial keratotomy (RK). Design: Retrospective study. Materials and Methods: A retrospective analysis of data of 18 eyes of 10 patients, who had undergone LASIK for refractive error following RK, was performed. All the patients had undergone RK in both eyes at least one year before LASIK. Parameters like uncorrected visual acuity (UCVA), best-corrected visual acuity (BCVA), contrast sensitivity, glare acuity and corneal parameters were evaluated both preoperatively and postoperatively. Statistical Software: STATA-9.0. Results: The mean UCVA before LASIK was 0.16±0.16 which improved to 0.64 ± 0.22 (P < 0.001) after one year following LASIK. Fourteen eyes (out of 18) had UCVA of ≥ 20/30 on Snellen's acuity chart at one year following LASIK. The mean BCVA before LASIK was 0.75 ± 0.18. This improved to 0.87 ± 0.16 at one year following LASIK. The mean spherical refractive error at the time of LASIK and at one year after the procedure was –5.37 ± 4.83 diopters (D) and –0.22 ± 1.45D, respectively. Only three eyes had a residual spherical refractive error of ≥ 1.0D at one year follow-up. In two eyes, we noted opening up of the RK incisions. No eye developed epithelial in-growth till 1 year after LASIK. Conclusion: LASIK is effective in treating refractive error following RK. However, it carries the risk of flap-related complications like opening up of the previously placed RK incisions and splitting of the corneal flap. PMID:21666312

Delayed onset Mycobacterium intracellulare keratitis after laser in situ keratomileusis

PubMed Central

Ko, JaeSang; Kim, Se Kyung; Yong, Dong Eun; Kim, Tae-im; Kim, Eung Kweon

2017-01-01

Abstract Rationale: Infectious keratitis is a relatively uncommon but potentially sight-threatening complication of laser in situ keratomileusis (LASIK). Mycobacterial keratitis is usually regarded as late onset keratitis among post-LASIK keratitis. There has been no documented case of Mycobacterium intracellulare post-LASIK keratitis of a long-latent period. Patient concerns: A 36-year-old man was referred to our out-patient clinic, for persistent corneal epithelial defect with intrastromal infiltration. He had undergone uneventful bilateral LASIK procedure 4 years before. He complained decreased vision, accompanied by ocular pain, photophobia, and redness in his left eye for 7 months. Diagnosis: Lamellar keratectomy was taken using femtosecond laser. Bacterial culture with sequenced bacterial 16s ribosomal DNA confirmed the organism to be M intracellulare. Interventions: After 3 months of administration of topical clarithromycin, amikacin, and moxifloxacin, the corneal epithelial defect was resolved and the infiltration was much improved. However, newly developed diffuse haziness with surrounding granular infiltration in the central cornea was noted. Drug toxicity was suspected and topical moxifloxacin was discontinued, resulting in resolution of the diffuse haze with infiltration. Outcome: The patient was followed up regularly without medication thereafter and recurrence was not found for 7 years. Lessons: This case presents the first case of M intracellulare keratitis after LASIK. LASIK surgeons should aware that post-LASIK keratitis can develop long after the operation and careful suspicion of infectious disease with meticulous diagnostic test is needed. PMID:29390522

Excimer laser photorefractive surgery of the cornea

NASA Astrophysics Data System (ADS)

Gaster, Ronald N.

1998-09-01

The 193 nm argon fluoride (ArF) excimer laser can effectively be used to change the radius of curvature of the cornea and thus alter the refractive state of the eye. This change allows myopic (nearsighted) patients to see well with less dependence on glasses or contact lenses. The two major techniques of laser refractive surgery currently in effect in the United States are photorefractive keratectomy (PRK) and laser in situ keratomileusis (LASIK). This paper will discuss these refractive cornea surgical techniques.

Small incision lenticule extraction (SMILE) and femtosecond laser LASIK: comparison of corneal wound healing and inflammation

PubMed Central

Dong, Zixian; Zhou, Xingtao; Wu, Jihong; Zhang, Zhehuan; Li, Tao; Zhou, Zimei; Zhang, Shenghai; Li, Gang

2014-01-01

Aim To evaluate and compare early corneal wound healing and inflammatory responses after small incision lenticule extraction (SMILE) versus femtosecond laser laser in situ keratomileusis (LASIK). Methods Thirty-six eyes of 36 rabbits underwent SMILE, while another 36 eyes of 36 rabbits were treated with femtosecond laser LASIK. All the eyes were subjected to the same refractive correction of −6.00 DS/−1.00 DC. Twelve eyes that had no surgery were included for control. After euthanisation, corneal tissue sections were evaluated with terminal deoxyribonucleotidyl transferase-mediated dUTP-digoxigenin nick-end labelling (TUNEL) assay to detect apoptosis at postoperative 4 and 24 h, immunocytochemistry for Ki67 to detect keratocyte proliferation at postoperative day 3, week 1 and month 1, and immunocytochemistry for CD11b to detect inflammation at postoperative day 1, day 3 and week 1, respectively. Results No adverse effects were noted after SMILE or LASIK. Corneal healing postoperatively was uneventful in all cases. There were significantly fewer TUNEL-positive corneal stromal cells after the SMILE procedure at 4 and 24 h postoperatively (p<0.01) compared with the LASIK procedure. In addition, immunocytochemistry showed significantly fewer Ki67-positive cells in the SMILE group than those in the femtosecond laser LASIK group at day 3 and week 1 postoperatively (p<0.05), but there was little expression of Ki67 at month 1 postoperatively in both groups. The CD11b-positive cells were significantly fewer in the SMILE group at day 1, day 3 and week 1 postoperatively (p<0.01). Conclusions SMILE induces less keratocyte apoptosis, proliferation and inflammation compared with femtosecond laser LASIK. PMID:24227802

Inhibition of recurrence of epithelial ingrowth with an amniotic membrane pressure patch to a laser in situ keratomileusis flap with a central stellate laceration: a case report.

PubMed

Kwon, Kye Yoon; Ji, Yong Woo; Lee, Jeihoon; Kim, Eung Kweon

2016-07-18

Surgical lifting and scraping is a well-known treatment for epithelial ingrowth, but treatment for epithelial ingrowth on the centrally perforated laser in situ keratomileusis (LASIK) flap has not been well studied. We present a patient who had epithelial ingrowth to the backside of the flap through a central LASIK flap laceration with a stellate shape. The patient had undergone uncomplicated bilateral LASIK surgery 3 years before the trauma. Because the epithelial ingrowth was suspected during the first visit 2 weeks after trauma, and definite epithelial ingrowth was noted during the additional 2 week observation period, the ingrown epithelial tissue was removed mechanically with a number 15 blade after lifting of the flap 4 weeks after the trauma. An amniotic membrane overlay was applied over the cornea and was sutured tightly to the episclera to firmly press down the flap to the remaining posterior stroma, to prevent growth of the epithelium again to the backside of the flap. At the last follow-up visit, 5 months after surgery, the patient's visual acuity remained stabilized with no sign of recurrent epithelial ingrowth. These results showed that an amniotic membrane patch can be a useful adjuvant in the treatment of epithelial ingrowth, even on the central stellate laceration of the LASIK flap over the visual axis.

Analysis of Macular and Retinal Nerve Fiber Layer Thickness in Children with Refractory Amblyopia after Femtosecond Laser-assisted Laser In situ Keratomileusis: A Retrospective Study

PubMed Central

Zhao, Peng-Fei; Zhou, Yue-Hua; Zhang, Jing; Wei, Wen-Bin

2017-01-01

Background: Localized macular edema and retinal nerve fiber layer (RNFL) thinning have been reported shortly after laser in situ keratomileusis (LASIK) in adults. However, it is still unclear how LASIK affects the retina of children. This study aimed to investigate the macular retina and RNFL thickness in children with refractive amblyopia who underwent femtosecond laser-assisted LASIK (FS-LASIK). Methods: In this study, we included 56 eyes of 32 patients with refractive amblyopia who underwent FS-LASIK in our hospital from January 2012 to December 2016. Foveal (foveal center retinal, parafoveal retinal, and perifoveal), macular inner retinal (superior and inferior), and peripapillary RNFL thicknesses (superior, inferior, temporal, and nasal) were measured using Fourier-domain optical coherence tomography before surgery and 1 day, 3 days, and 1 week after surgery. We divided these patients into three groups based on their refractive error: High myopic group with 22 eyes (equivalent sphere, >6.00 D), mild myopic group with 19 eyes (equivalent sphere, 0–6.00 D), and hyperopic group with 15 eyes (equivalent sphere, >+0.50 D). We compared the macular retina and RNFL thickness before and after LASIK. A paired simple t-test was used for data analysis. Results: One week after surgery, the visual acuity for all 56 eyes of the 32 patients reached their preoperative best-corrected vision. Visual acuity improved two lines or better for 31% of the patients. The residual refractive errors in 89% of the patients were within ±0.5 D. In the high myopic group, the foveal center retinal and parafoveal retinal thicknesses were thicker 1 day and 3 days after surgery than before surgery (t = 2.689, P = 0.012; t = 2.383, P = 0.018, respectively); no significant difference was found 1 week after surgery (P > 0.05). The foveal center retinal and parafoveal retinal thicknesses were greater 1 day after surgery than they were before surgery (P = 0.000 and P = 0.005, respectively) in the

Analysis of Macular and Retinal Nerve Fiber Layer Thickness in Children with Refractory Amblyopia after Femtosecond Laser-assisted Laser In situ Keratomileusis: A Retrospective Study.

PubMed

Zhao, Peng-Fei; Zhou, Yue-Hua; Zhang, Jing; Wei, Wen-Bin

2017-09-20

Localized macular edema and retinal nerve fiber layer (RNFL) thinning have been reported shortly after laser in situ keratomileusis (LASIK) in adults. However, it is still unclear how LASIK affects the retina of children. This study aimed to investigate the macular retina and RNFL thickness in children with refractive amblyopia who underwent femtosecond laser-assisted LASIK (FS-LASIK). In this study, we included 56 eyes of 32 patients with refractive amblyopia who underwent FS-LASIK in our hospital from January 2012 to December 2016. Foveal (foveal center retinal, parafoveal retinal, and perifoveal), macular inner retinal (superior and inferior), and peripapillary RNFL thicknesses (superior, inferior, temporal, and nasal) were measured using Fourier-domain optical coherence tomography before surgery and 1 day, 3 days, and 1 week after surgery. We divided these patients into three groups based on their refractive error: High myopic group with 22 eyes (equivalent sphere, >6.00 D), mild myopic group with 19 eyes (equivalent sphere, 0-6.00 D), and hyperopic group with 15 eyes (equivalent sphere, >+0.50 D). We compared the macular retina and RNFL thickness before and after LASIK. A paired simple t-test was used for data analysis. One week after surgery, the visual acuity for all 56 eyes of the 32 patients reached their preoperative best-corrected vision. Visual acuity improved two lines or better for 31% of the patients. The residual refractive errors in 89% of the patients were within ±0.5 D. In the high myopic group, the foveal center retinal and parafoveal retinal thicknesses were thicker 1 day and 3 days after surgery than before surgery (t = 2.689, P = 0.012; t = 2.383, P = 0.018, respectively); no significant difference was found 1 week after surgery (P > 0.05). The foveal center retinal and parafoveal retinal thicknesses were greater 1 day after surgery than they were before surgery (P = 0.000 and P = 0.005, respectively) in the mild myopic and hyperopic groups

Segmentation of 830- and 1310-nm LASIK corneal optical coherence tomography images

NASA Astrophysics Data System (ADS)

Li, Yan; Shekhar, Raj; Huang, David

2002-05-01

Optical coherence tomography (OCT) provides a non-contact and non-invasive means to visualize the corneal anatomy at micron scale resolution. We obtained corneal images from an arc-scanning (converging) OCT system operating at a wavelength of 830nm and a fan-shaped-scanning high-speed OCT system with an operating wavelength of 1310nm. Different scan protocols (arc/fan) and data acquisition rates, as well as wavelength dependent bio-tissue backscatter contrast and optical absorption, make the images acquired using the two systems different. We developed image-processing algorithms to automatically detect the air-tear interface, epithelium-Bowman's layer interface, laser in-situ keratomileusis (LASIK) flap interface, and the cornea-aqueous interface in both kinds of images. The overall segmentation scheme for 830nm and 1310nm OCT images was similar, although different strategies were adopted for specific processing approaches. Ultrasound pachymetry measurements of the corneal thickness and Placido-ring based corneal topography measurements of the corneal curvature were made on the same day as the OCT examination. Anterior/posterior corneal surface curvature measurement with OCT was also investigated. Results showed that automated segmentation of OCT images could evaluate anatomic outcome of LASIK surgery.

Effect of the equivalent refractive index on intraocular lens power prediction with ray tracing after myopic laser in situ keratomileusis.

PubMed

Canovas, Carmen; van der Mooren, Marrie; Rosén, Robert; Piers, Patricia A; Wang, Li; Koch, Douglas D; Artal, Pablo

2015-05-01

To determine the impact of the equivalent refractive index (ERI) on intraocular lens (IOL) power prediction for eyes with previous myopic laser in situ keratomileusis (LASIK) using custom ray tracing. AMO B.V., Groningen, the Netherlands, and the Department of Ophthalmology, Baylor College of Medicine, Houston, Texas, USA. Retrospective data analysis. The ERI was calculated individually from the post-LASIK total corneal power. Two methods to account for the posterior corneal surface were tested; that is, calculation from pre-LASIK data or from post-LASIK data only. Four IOL power predictions were generated using a computer-based ray-tracing technique, including individual ERI results from both calculation methods, a mean ERI over the whole population, and the ERI for normal patients. For each patient, IOL power results calculated from the four predictions as well as those obtained with the Haigis-L were compared with the optimum IOL power calculated after cataract surgery. The study evaluated 25 patients. The mean and range of ERI values determined using post-LASIK data were similar to those determined from pre-LASIK data. Introducing individual or an average ERI in the ray-tracing IOL power calculation procedure resulted in mean IOL power errors that were not significantly different from zero. The ray-tracing procedure that includes an average ERI gave a greater percentage of eyes with an IOL power prediction error within ±0.5 diopter than the Haigis-L (84% versus 52%). For IOL power determination in post-LASIK patients, custom ray tracing including a modified ERI was an accurate procedure that exceeded the current standards for normal eyes. Copyright © 2015 ASCRS and ESCRS. Published by Elsevier Inc. All rights reserved.

A Multicenter Retrospective Survey of Refractive Surgery in 78,248 Eyes.

PubMed

Kamiya, Kazutaka; Igarashi, Akihito; Hayashi, Ken; Negishi, Kazuno; Sato, Masaki; Bissen-Miyajima, Hiroko

2017-09-01

To retrospectively evaluate the current practice, trends, and outcomes of refractive surgery in Japan. This multicenter survey comprised 78,248 eyes of 39,727 consecutive patients who underwent refractive surgery at 45 major institutions in Japan. The corresponding ophthalmologists responded to a selfadministered questionnaire. The authors especially evaluated the safety, efficacy, predictability, stability, and adverse events of LASIK and phakic intraocular lens (IOL) implantation 3 months postoperatively. The most common refractive surgery was LASIK (90.9%), followed by corneal inlay (5.0%), posterior chamber phakic IOL implantation (1.3%), laser-assisted subepithelial keratomileusis (1.0%), refractive lens exchange (0.9%), photorefractive keratectomy (0.3%), and refractive lenticule extraction (0.2%). For subgroup analysis, 69,987 eyes (99.5%) and 67,512 eyes (95.9%) achieved corrected and uncorrected distance visual acuity of 20/20 or better, respectively, after LASIK, and 935 eyes (98.8%) and 890 eyes (94.1%), respectively, after phakic IOL implantation. There were 69,176 eyes (98.3%) and 908 eyes (96.0%) within ±1.00 diopter (D) of the attempted correction after LASIK and phakic IOL implantation, respectively. There were 1,926 eyes (2.7%) and 1 eye (0.1%) with changes in refraction of 1.00 D or less from 1 week to 3 months after LASIK and phakic IOL implantation, respectively. No vision-threatening complications occurred in any case. According to this survey, LASIK remains the most prevalent surgical technique in Japan. Both LASIK and phakic IOL implantation offered good safety and efficacy outcomes, yielding predictable and stable results. [J Refract Surg. 2017;33(9):598-602.]. Copyright 2017, SLACK Incorporated.

Comparison of optical quality after implantable collamer lens implantation and wavefront-guided laser in situ keratomileusis

PubMed Central

Liu, Hong-Ting; Zhou, Zhou; Luo, Wu-Qiang; He, Wen-Jing; Agbedia, Owhofasa; Wang, Jiang-Xia; Huang, Jian-Zhong; Gao, Xin; Kong, Min; Li, Min; Li, Li

2018-01-01

AIM To compare the optical quality after implantation of implantable collamer lens (ICL) and wavefront-guided laser in situ keratomileusis (WG-LASIK). METHODS The study included 40 eyes of 22 patients with myopia who accepted ICL implantation and 40 eyes of 20 patients with myopia who received WG-LASIK. Before surgery and three months after surgery, the objective scattering index (OSI), the values of modulation transfer function (MTF) cutoff frequency, Strehl ratio, and the Optical Quality Analysis System (OQAS) values (OVs) were accessed. The higher order aberrations (HOAs) data including coma, trefoil, spherical, 2nd astigmatism and tetrafoil were also obtained. For patients with pupil size <6 mm, HOAs data were analyzed for 4 mm-pupil diameter. For patients with pupil size ≥6 mm, HOAs data were calculated for 6 mm-pupil diameter. Visual acuity, refraction, pupil size and intraocular pressures were also recorded. RESULTS In both ICL and WG-LASIK group, significant improvements in visual acuities were found postoperatively, with a significant reduction in spherical equivalent (P< 0.001). After the ICL implantation, the OSI decreased slightly from 2.34±1.92 to 2.24±1.18 with no statistical significance (P=0.62). While in WG-LASIK group, the OSI significantly increased from 0.68±0.43 preoperatively to 0.91±0.53 postoperatively (Wilcoxon signed ranks test, P=0.000). None of the mean MTF cutoff frequency, Strehl ratio, OVs showed statistically significant changes in both ICL and WG-LASIK groups. In the ICL group, there were no statistical differences in the total HOAs for either 4 mm-pupil or 6 mm-pupil. In the WG-LASIK group, the HOA parameters increased significantly at 4 mm-pupil. The total ocular HOAs, coma, spherical and 2nd astigmatism were 0.12±0.06, 0.06±0.03, 0.00±0.03, 0.02±0.01, respectively. After the operation, these values were increased into 0.16±0.07, 0.08±0.05, -0.04±0.04, 0.03±0.01 respectively (Wilcoxon signed ranks test, all P<0

Comparison of optical quality after implantable collamer lens implantation and wavefront-guided laser in situ keratomileusis.

PubMed

Liu, Hong-Ting; Zhou, Zhou; Luo, Wu-Qiang; He, Wen-Jing; Agbedia, Owhofasa; Wang, Jiang-Xia; Huang, Jian-Zhong; Gao, Xin; Kong, Min; Li, Min; Li, Li

2018-01-01

To compare the optical quality after implantation of implantable collamer lens (ICL) and wavefront-guided laser in situ keratomileusis (WG-LASIK). The study included 40 eyes of 22 patients with myopia who accepted ICL implantation and 40 eyes of 20 patients with myopia who received WG-LASIK. Before surgery and three months after surgery, the objective scattering index (OSI), the values of modulation transfer function (MTF) cutoff frequency, Strehl ratio, and the Optical Quality Analysis System (OQAS) values (OVs) were accessed. The higher order aberrations (HOAs) data including coma, trefoil, spherical, 2 nd astigmatism and tetrafoil were also obtained. For patients with pupil size <6 mm, HOAs data were analyzed for 4 mm-pupil diameter. For patients with pupil size ≥6 mm, HOAs data were calculated for 6 mm-pupil diameter. Visual acuity, refraction, pupil size and intraocular pressures were also recorded. In both ICL and WG-LASIK group, significant improvements in visual acuities were found postoperatively, with a significant reduction in spherical equivalent ( P < 0.001). After the ICL implantation, the OSI decreased slightly from 2.34±1.92 to 2.24±1.18 with no statistical significance ( P =0.62). While in WG-LASIK group, the OSI significantly increased from 0.68±0.43 preoperatively to 0.91±0.53 postoperatively (Wilcoxon signed ranks test, P =0.000). None of the mean MTF cutoff frequency, Strehl ratio, OVs showed statistically significant changes in both ICL and WG-LASIK groups. In the ICL group, there were no statistical differences in the total HOAs for either 4 mm-pupil or 6 mm-pupil. In the WG-LASIK group, the HOA parameters increased significantly at 4 mm-pupil. The total ocular HOAs, coma, spherical and 2 nd astigmatism were 0.12±0.06, 0.06±0.03, 0.00±0.03, 0.02±0.01, respectively. After the operation, these values were increased into 0.16±0.07, 0.08±0.05, -0.04±0.04, 0.03±0.01 respectively (Wilcoxon signed ranks test, all P <0.05). At 6 mm

Efficacy of punctal occlusion in management of dry eyes after laser in situ keratomileusis for myopia.

PubMed

Alfawaz, Abdullah M; Algehedan, Saeed; Jastaneiah, Sabah S; Al-Mansouri, Samir; Mousa, Ahmed; Al-Assiri, Abdullah

2014-03-01

To evaluate the effect of punctal plug use in preventing dry eye after laser in situ keratomileusis (LASIK). A randomized clinical trial at a tertiary eye care center, Riyadh, Saudi Arabia. Participants underwent LASIK for myopia in both eyes and a lower punctal occlusion in one eye only while the other eye served as control. Both eyes received the same postoperative medications except for lubricant duration (subject eye: four times per day for one week; control eye: four times per day for 6 months). Participants were evaluated at 1 week, 2, and 6 months after surgery for signs and symptoms of dry eye. The main outcome measures were visual acuity; ocular surface parameters; and Ocular Surface Disease Index questionnaire. Seventy-eight eyes of 39 patients were included in this study. The Ocular Surface Disease Index scores of eyes with punctal plugs were better at all follow-up visits, and the differences between both eyes were statistically significant (1 week, p < 0.0001; 2 months, p < 0.0001; 6 months, p = 0.008). At the final follow-up visit, the percentage of normal eyes was higher in eyes with punctal plugs for all ocular surface parameters (Schirmer 1 test, 94.9%; tear breakup time, 77.8%; punctate epithelial keratitis score, 71.8%) compared to eyes without occlusion (Schirmer 1 test, 92.3%; tear breakup time, 58.3%; punctate epithelial keratitis score, 53.8%); however, such differences were not statistically significant. Punctal plug insertion after LASIK surgeries may minimize the need for frequent lubricant application and hence improve patient satisfaction.

Three-year results of small incision lenticule extraction and wavefront-guided femtosecond laser-assisted laser in situ keratomileusis for correction of high myopia and myopic astigmatism

PubMed Central

Xia, Li-Kun; Ma, Jing; Liu, He-Nan; Shi, Ce; Huang, Qing

2018-01-01

AIM To compare and calculate the 3-year refractive results, higher-order aberrations (HOAs), contrast sensitivity (CS) and dry eye parameters after small incision lenticule extraction (SMILE) and wavefront-guided femtosecond laser-assisted laser in situ keratomileusis (FS-LASIK) for correction of high myopia and myopic astigmatism. METHODS In this prospective, non-randomized comparative study, 78 eyes with spherical equivalent (SE) of -8.11±1.09 diopters (D) received a SMILE surgery, and 65 eyes with SE of -8.05±1.12 D received a wavefront-guided FS-LASIK surgery with the VisuMax femtosecond laser (Carl Zeiss Meditec, Jena, Germany) for flap cutting. Visual acuity, manifest refraction, CS, HOAs, ocular surface disease index (OSDI) and tear break-up time (TBUT) were evaluated during a 3-year follow-up. RESULTS The difference of uncorrected distance visual acuity (UDVA) postoperatively was achieved at 1mo and at 3mo, whereas the difference of the mean UDVA between two groups at 3y were not statistically significant (t=-1.59, P=0.13). The postoperative change of SE was 0.89 D in the FS-LASIK group (t=5.76, P=0.00), and 0.14 D in the SMILE group (t=0.54, P=0.59) from 1mo to 3y after surgery. At 3-year postoperatively, both HOAs and spherical aberrations in the SMILE group were obviously less than those in the FS-LASIK group (P=0.00), but the coma root mean square (RMS) was higher in the SMILE group (0.59±0.26) than in the FS-LASIK group (0.29±0.14, P=0.00). The mesopic CS values between two groups were not statistically significant at 3y postoperatively. Compared with the FS-LASIK group, lower OSDI scores and longer TBUT values were found in the SMILE group at 1mo and 3mo postoperatively. With regard to safety, no eye lost any line of CDVA in both groups at 3y after surgery. CONCLUSION Both SMILE and wavefront-guided FS-LASIK procedures provide good visual outcomes. Both procedures are effective and safe, but SMILE surgery achieve more stable long-term refractive

Dry eye disease after refractive surgery: comparative outcomes of small incision lenticule extraction versus LASIK.

PubMed

Denoyer, Alexandre; Landman, Elise; Trinh, Liem; Faure, Jean-François; Auclin, François; Baudouin, Christophe

2015-04-01

To compare small incision lenticule extraction (SMILE) versus LASIK for post-refractive dry eye disease. Prospective, comparative, nonrandomized clinical study. Thirty patients scheduled for bilateral myopic SMILE and 30 age-, sex-, and refraction-matched patients scheduled for bilateral myopic LASIK were enrolled and followed for 6 months after the surgery. Complete evaluation of dry eye disease was performed at 1 and 6 months postoperatively, which included vision-related quality of life (Ocular Surface Disease Index [OSDI]), clinical examinations (tear film breakup time [TBUT], Schirmer I test, corneal staining), and tear osmolarity measurements, together with an overall severity score. Function and morphology of the corneal innervation were evaluated by corneal esthesiometry and subbasal nerve imaging using in vivo confocal microscopy (IVCM). Overall analysis of dry eye disease and corneal innervation. High incidence of mild to moderate dry eye disease was observed in both groups 1 month postoperatively, which remained significantly higher in the LASIK group than in the SMILE group 6 months after surgery (overall severity score [0-4]: 1.2±1.1 vs. 0.2±0.4, respectively, P < 0.01), leading to more frequent use of tear substitutes over the long term. Corneal sensitivity was better in SMILE than in LASIK eyes 1 month postoperatively (3.5±1.79 vs. 2.45±2.48, respectively, P < 0.01) and then recovered to statistically similar values at 6 months. Corneal nerve density, number of long fibers, and branchings as assessed by IVCM were significantly higher in the SMILE group compared with the LASIK group 1 and 6 months after surgery. Corneal sensitivity was negatively correlated with dry eye-related corneal damage (R² = 0.48, P < 0.01), and the long fiber nerve density was independently correlated with the OSDI score (R² = 0.50, P < 0.01) and the Schirmer test (R² = 0.21, P < 0.01) 6 months postoperatively. The SMILE procedure has a less pronounced impact on the

Goblet cell response after photorefractive keratectomy and laser in situ keratomileusis

PubMed Central

Ryan, Denise S.; Bower, Kraig S.; Sia, Rose K.; Shatos, Marie A.; Howard, Robin S.; Mines, Michael J.; Stutzman, Richard D.; Dartt, Darlene A.

2017-01-01

PURPOSE To determine whether patients without dry eye preoperatively have an altered conjunctival goblet cell density and mucin secretion postoperatively and to explore what factors affect changes in goblet cell density and mucin secretion. SETTING The former Walter Reed Army Medical Center, Washington, DC, USA. DESIGN Prospective nonrandomized clinical study. METHODS Impression cytology was used to determine conjunctival goblet cell density before and 1 week, 1 month, and 3 months after photorefractive keratectomy (PRK) or laser in situ keratomileusis (LASIK). The McMonnies questionnaire, Schirmer test, tear breakup time, corneal sensitivity, rose bengal staining, and computerized videokeratoscopy were also performed to assess tear-film and ocular-surface health. RESULTS The ratio of goblet cell to total cells changed postoperatively from baseline in both groups (P < .001). The most significant change was a median 29% decrease 1 month postoperatively. However, there were no significant differences between groups over time (P = .772). The ratio of filled goblet cell to total goblet cell did not change significantly over the same time period (P = .128), and there were no significant differences between the PRK group and the LASIK group over time (P = .282). CONCLUSIONS Patients without apparent dry eye had altered conjunctival goblet cell population after PRK or LASIK. The conjunctival goblet cell population tended to decrease in the early postoperative period after either surgery and was most affected by preoperative goblet cell density. The changes in the tear film and ocular surface did not seem to affect goblet cell mucin secretion after either procedure. PMID:27531295

When case report became case series: 45 cases of late traumatic flap complications after laser-assisted in situ keratomileusis and review of Chinese literature.

PubMed

Xiao, Jianhe; Jiang, Caihui; Zhang, Maonian; Jiang, Hua; Li, Shiyang; Zhang, Ying

2014-09-01

To report 45 cases of late traumatic flap complications after laser-assisted in situ keratomileusis (LASIK) and discuss the continually increasing number of cases in China. A multicentre retrospective survey of eye injuries was carried in 31 military hospitals from January 2006 to December 2011. Detailed information from the medical records of all 92 cases with a history of prior LASIK treatment were collected and summarised, with respect to visual acuity (VA), flap condition, treatment and final outcome. All Chinese publications relevant to late traumatic flap complications in Chinese patients were retrieved and summarised. 92 inpatients (92 eyes) underwent LASIK surgery; 45 of these had traumatic LASIK flap complications. Flap dislocation was the commonest and most needed surgical repair. VA after treatment was good and no statistically significant difference was observed when compared with the 47 cases without flap complications. 109 articles related to late traumatic flap complications after LASIK were retrieved from four Chinese document databases. There were 550 cases of late traumatic flap complications. From 2004, case reports became more common; 10 or more cases were reported in some case series. VA of most cases was good and there was no remarkable vision loss after treatment. Late traumatic flap complications after LASIK have become more frequent in China, although the prognosis of most cases is good. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://group.bmj.com/group/rights-licensing/permissions.

Defining the content of patient questionnaires: reasons for seeking laser in situ keratomileusis for myopia.

PubMed

Khan-Lim, Doreen; Craig, Jennifer P; McGhee, Charles N J

2002-05-01

To determine the relative importance of patients' motives for having laser in situ keratomileusis (LASIK) for myopia. The Corneal Diseases and Excimer Laser Research Unit, University of Dundee, Ninewells Hospital and Medical School, Dundee, Scotland. Twenty-one cards printed with potential reasons for having LASIK and 3 blank cards for respondents to include additional motives were posted to 71 patients who had myopic LASIK. The cards were ranked by each respondent in order of personal importance and returned for analysis. The response rate was 77.5%. The mean age of the 19 male and 37 female respondents was 41.7 years +/- 9.3 (SD) and the mean preoperative spherical equivalent, -9.26 +/- 4.58 diopters. The primary reasons for seeking treatment (percentage of respondents ranking topic within the top 5) were improvement of unaided social vision (69.1%), intolerance to spectacles/contact lenses (65.5%), and freedom from spectacles/contact lenses (61.8%). Almost 70% of respondents ranked 1 of these reasons as the most important. General inconvenience of spectacles/contact lenses and the desire to pursue sports and leisure activities also ranked high (52.7% and 36.4%, respectively). Consistent with previous work, better unaided vision, combined with the inconvenience of or intolerance to spectacles or contact lenses, provided the main incentives to have LASIK for myopia, while improved cosmesis was relatively unimportant (29.1%). The results of this study will allow the design of satisfaction questionnaires that are better directed toward establishing satisfaction of specific, relevant functional and psychological aspects of refractive surgery that are important to patients.

[Comparative results evaluation of residual myopia and astigmatism correction after radial keratotomy by photorefraction keratectomy and laser specialized keratomileusis].

PubMed

Dias-Martines, T E; Sheludchenko, V M; Kurenkov, V V

1999-01-01

The results of correction of residual myopia by photorefraction keratectomy (PRK) (51 eyes) and laser specialized keratomileusis (LASIK) (36 eyes) after radial keratotomy (RK) are compared. The patients were observed for up to 12 months. After PRK, 7.3% patients developed late fleur of the cornea, evaluated by at least 2 points. The incidence of fleur directly depended on the value of residual myopia. After LASIK none of the patients developed such fleur. The best visual acuity (0.5 and higher without correction) was attained in 70.73% after PRK and RK, vs. 100% after LASIK. The results of photorefraction operations and severity of residual myopia after RK correlated. In residual myopia of up to -3 diopters the results of correction by PRK and LASIK were virtually the same. In residual myopia higher than -3 diopters, LASIK is preferable.

Effect of Macrophage Migration Inhibitory Factor on Corneal Sensitivity after Laser In Situ Keratomileusis in Rabbit

PubMed Central

Hose, Stacey; Gongora, Celine; Sinha, Debasish; O'Brien, Terrence

2014-01-01

Purpose To investigate the effect of macrophage migration inhibitory factor (MIF) on corneal sensitivity after laser in situ keratomileusis (LASIK) surgery. Methods New Zealand white rabbits were used in this study. A hinged corneal flap (160-µm thick) was created with a microkeratome, and -3.0 diopter excimer laser ablation was performed. Expressions of MIF mRNA in the corneal epithelial cells and surrounding inflammatory cells were analyzed using reverse transcription polymerase chain reaction at 48 hours after LASIK. After LASIK surgery, the rabbits were topically given either 1) a balanced salt solution (BSS), 2) MIF (100 ng/mL) alone, or 3) a combination of nerve growth factor (NGF, 100 ug/mL), neurotrophine-3 (NT-3, 100 ng/mL), interleukin-6 (IL-6, 5 ng/mL), and leukemia inhibitory factor (LIF, 5 ng/mL) four times a day for three days. Preoperative and postoperative corneal sensitivity at two weeks and at 10 weeks were assessed using the Cochet-Bonnet esthesiometer. Results Expression of MIF mRNA was 2.5-fold upregulated in the corneal epithelium and 1.5-fold upregulated in the surrounding inflammatory cells as compared with the control eyes. Preoperative baseline corneal sensitivity was 40.56 ± 2.36 mm. At two weeks after LASIK, corneal sensitivity was 9.17 ± 5.57 mm in the BSS treated group, 21.92 ± 2.44 mm in the MIF treated group, and 22.42 ± 1.59 mm in the neuronal growth factors-treated group (MIF vs. BSS, p < 0.0001; neuronal growth factors vs. BSS, p < 0.0001; MIF vs. neuronal growth factors, p = 0.815). At 10 weeks after LASIK, corneal sensitivity was 15.00 ± 9.65, 35.00 ± 5.48, and 29.58 ± 4.31 mm respectively (MIF vs. BSS, p = 0.0001; neuronal growth factors vs. BSS, p = 0.002; MIF vs. neuronal growth factors, p = 0.192). Treatment with MIF alone could achieve as much of an effect on recovery of corneal sensation as treatment with combination of NGF, NT-3, IL-6, and LIF. Conclusions Topically administered MIF plays a significant role in the

Effect of macrophage migration inhibitory factor on corneal sensitivity after laser in situ keratomileusis in rabbit.

PubMed

Hyon, Joon Young; Hose, Stacey; Gongora, Celine; Sinha, Debasish; O'Brien, Terrence

2014-04-01

To investigate the effect of macrophage migration inhibitory factor (MIF) on corneal sensitivity after laser in situ keratomileusis (LASIK) surgery. New Zealand white rabbits were used in this study. A hinged corneal flap (160-µm thick) was created with a microkeratome, and -3.0 diopter excimer laser ablation was performed. Expressions of MIF mRNA in the corneal epithelial cells and surrounding inflammatory cells were analyzed using reverse transcription polymerase chain reaction at 48 hours after LASIK. After LASIK surgery, the rabbits were topically given either 1) a balanced salt solution (BSS), 2) MIF (100 ng/mL) alone, or 3) a combination of nerve growth factor (NGF, 100 ug/mL), neurotrophine-3 (NT-3, 100 ng/mL), interleukin-6 (IL-6, 5 ng/mL), and leukemia inhibitory factor (LIF, 5 ng/mL) four times a day for three days. Preoperative and postoperative corneal sensitivity at two weeks and at 10 weeks were assessed using the Cochet-Bonnet esthesiometer. Expression of MIF mRNA was 2.5-fold upregulated in the corneal epithelium and 1.5-fold upregulated in the surrounding inflammatory cells as compared with the control eyes. Preoperative baseline corneal sensitivity was 40.56 ± 2.36 mm. At two weeks after LASIK, corneal sensitivity was 9.17 ± 5.57 mm in the BSS treated group, 21.92 ± 2.44 mm in the MIF treated group, and 22.42 ± 1.59 mm in the neuronal growth factors-treated group (MIF vs. BSS, p < 0.0001; neuronal growth factors vs. BSS, p < 0.0001; MIF vs. neuronal growth factors, p = 0.815). At 10 weeks after LASIK, corneal sensitivity was 15.00 ± 9.65, 35.00 ± 5.48, and 29.58 ± 4.31 mm respectively (MIF vs. BSS, p = 0.0001; neuronal growth factors vs. BSS, p = 0.002; MIF vs. neuronal growth factors, p = 0.192). Treatment with MIF alone could achieve as much of an effect on recovery of corneal sensation as treatment with combination of NGF, NT-3, IL-6, and LIF. Topically administered MIF plays a significant role in the early recovery of corneal

Effect of femtosecond and microkeratome flaps creation on the cornea biomechanics during laser in situ keratomileusis: one year follow-up

PubMed Central

Sun, Qian; Deng, Zheng-Zheng; Zhou, Yue-Hua; Zhang, Jing; Peng, Xiao-Yan

2016-01-01

AIM To compare the corneal biomechanical outcomes at one year after laser in situ keratomileusis (LASIK) with the flaps created by Ziemer and Moria M2 microkeratome with 110 head and -20 blade. METHODS Totally 100 eyes of 50 consecutive patients were enrolled in this prospective study and divided into two groups for corneal flaps created by ZiemerFemto LDV and Moria M2 microkeratome with 110 head and -20 blade. Corneal biomechanical properties including cornea resistance factor (CRF) and cornea hysteresis (CH) were measured before and 1, 3, 6, 12mo after surgery by ocular response analyzer. Central cornea thickness and corneal flap thickness were measured by optical coherence tomography. RESULTS The ablation depth (P=0.693), residual corneal thickness (P=0.453), and postoperative corneal curvature (P=0.264) were not significant different between Ziemer group and Moria 110-20 group after surgery. The residual stromal bed thickness, corneal flap thickness, CH and CRF at 12mo after surgery were significant different between Ziemer group and Moria 110-20 group (P<0.01);Ziemer group gained better corneal biomechanical results. The CRF and CH increased gradually from 1 to 12mo after surgery in Ziemer group, increased from 1 to 6mo but decreased from 6 to 12mo in Moria 110-20 group. Both CRF and CH at one year after surgery increased with the increasing of residual cornea thickness; pre-LASIK CRF, CRF also increased with residual stromal bed thickness, while CH decreased with the increasing of pre-LASIK intraocular pressure and cornea flap thickness (P<0.01). CONCLUSION In one year follow-up, femtosecond laser can provide better cornea flaps with stable cornea biomechanics than mechanical microkeratome. PMID:27803856

Aircrew Performance Cutting-Edge Tech: Emerging Human Performance Enhancement Technology Vision in Support of Operational Military Aviation Strategy

DTIC Science & Technology

2002-04-01

Origin and History, (RK, PRK , LASIK ) Refractive surgery was first considered as early as 1898 by a Dutch professor and was unsuccessfully attempted in...Keratomileusis ( LASIK ) LASIK offers the greatest potential for improving aviator vision and is the latest PRK -similar procedure. First, a flap of...showed that after LASIK , subjects did not exhibit a refractive shift of clinical significance.39 Therefore LASIK and PRK , recipients had no significant

Relative peripheral refraction across 4 meridians after orthokeratology and LASIK surgery.

PubMed

Queirós, António; Amorim-de-Sousa, Ana; Lopes-Ferreira, Daniela; Villa-Collar, César; Gutiérrez, Ángel Ramón; González-Méijome, José Manuel

2018-01-01

To characterize the axial and off-axis refraction across four meridians of the retina in myopic eyes before and after Orthokeratology (OK) and LASIK surgery. Sixty right eyes with a spherical equivalent (M) between - 0.75 to - 5.25 D (cylinder <- 1.00 D) underwent LASIK (n = 26) or OK (n = 34) to treat myopia. Axial and off-axis refraction were measured with an open-field autorefractometer before and after stabilized treatments. Off-axis measurements were obtained for the horizontal (35° nasal and temporal retina) and vertical (15° superior and inferior retina) meridians, and for two oblique directions (45-225° and 135-315°) up to 20° of eccentricity. The refractive profile was addressed as relative peripheral refractive error (RPRE). OK and LASIK post-treatment results showed an increase of myopic relative refraction at several eccentric locations. At the four meridians evaluated, the M component of the pre-treatment RPRE values was not statistically different ( p > 0.05) from the post-treatment RPRE within 30° and 20° of the central visual field after LASIK and OK, respectively. These results demonstrated that the treatment zone warrants an optimal central field of vision. The present study gives an overview of RPRE after refractive corneal reshaping treatments (OK and LASIK) across vertical, horizontal and two oblique meridians together. This allows a 3D representation of RPRE at the retina and shows that the myopic shift induced by both treatments is more relevant in horizontal directions.

Outcomes of topography-guided versus wavefront-optimized laser in situ keratomileusis for myopia in virgin eyes.

PubMed

Jain, Arun Kumar; Malhotra, Chintan; Pasari, Anand; Kumar, Pawan; Moshirfar, Majid

2016-09-01

To compare the outcomes of topography-guided and wavefront-optimized treatment in patients having laser in situ keratomileusis (LASIK) for myopia. Advanced Eye Centre, Post Graduate Institute of Medical Education and Research, Chandigarh, India. Prospective contralateral-eye case study. Patients had topography-guided LASIK in 1 eye and wavefront-optimized LASIK in the contralateral eye using the Customized Refractive Surgery Master software and Mel 80 excimer laser. Refractive (residual manifest refraction spherical equivalent [MRSE], higher-order aberrations [HOAs]), and visual (uncorrected distance visual acuity [UDVA] and photopic and mesopic contrast sensitivity) outcomes were prospectively analyzed 6 months postoperatively. The study comprised 35 patients. The UDVA was 0.0 logMAR or better and the postoperative residual MRSE was ±0.50 diopter in 94.29% of eyes in the topography-guided group and 85.71% of eyes in the wavefront-optimized group (P = .09). More eyes in the topography-guided group than in the wavefront-optimized group had a UDVA of -0.1 logMAR or better (P = .04). Topography-guided LASIK was associated with less deterioration of mesopic contrast sensitivity at higher spatial frequencies (12 cycles per degree [cpd] and 18 cpd) and lower amounts of induced coma (P = .04) and spherical aberration (P = .04). Less stromal tissue was ablated in the topography-guided group (mean 61.57 μm ± 16.23 [SD]) than in the wavefront-optimized group (mean 79.71 ± 14.81 μm) (P < .001). Although topography-guided LASIK and wavefront-optimized LASIK gave excellent results, topography-guided LASIK was associated with better contrast sensitivity, lower induction of HOAs, and a smaller amount of tissue ablation. None of the authors has a financial or proprietary interest in any material or method mentioned. Copyright © 2016 ASCRS and ESCRS. Published by Elsevier Inc. All rights reserved.

Small Incision Lenticule Extraction (SMILE) versus Femtosecond Laser-Assisted In Situ Keratomileusis (FS-LASIK) for Myopia: A Systematic Review and Meta-Analysis

PubMed Central

Shen, Zeren; Shi, Keda; Yu, Yinhui; Yu, Xiaoning; Lin, Yuchen; Yao, Ke

2016-01-01

Purpose The goal of this study was to compare small incision lenticule extraction (SMILE) with femtosecond laser-assisted in situ keratomileusis (FS-LASIK) for treating myopia. Methods The CENTRAL, EMBASE, PubMed databases and a Chinese database (SinoMed) were searched in May of 2016. Twelve studies with 1,076 eyes, which included three randomized controlled trials (RCTs) and nine cohorts, met our inclusion criteria. The overall quality of evidence was evaluated using the Grading of Recommendations Assessment, Development and Evaluation (GRADE) working group framework. Data were extracted and analysed at three to six months postoperatively. Primary outcome measures included a loss of one or more lines of best spectacle corrected visual acuity (BSCVA), uncorrected visual acuity (UCVA) of 20/20 or better, mean logMAR UCVA, postoperative mean spherical equivalent (SE) and postoperative refraction within ±1.0 D of the target refraction. Secondary outcome measures included ocular surface disease index (OSDI), tear breakup time (TBUT) and Schirmer’s 1 test (S1T) as dry eye parameters, along with corneal sensitivity. Results The overall quality of evidence was considered to be low to very low. Pooled results revealed no significant differences between the two groups with regard to a loss of one or more lines in the BSCVA (OR 1.71; 95% CI: 0.81, 3.63; P = 0.16), UCVA of 20/20 or better (OR 0.71; 95% CI: 0.44, 1.15; P = 0.16), logMAR UCVA (MD 0.00; 95% CI: -0.03, 0.04; P = 0.87), postoperative refractive SE (MD -0.00; 95% CI: -0.05, 0.05; P = 0.97) or postoperative refraction within ±1.0 D of the target refraction (OR 0.78; 95% CI: 0.22, 2.77; P = 0.70) within six months postoperatively. The pooled analysis also indicated that the FS-LASIK group suffered more severely from dry eye symptoms (OSDI; MD -6.68; 95% CI: -11.76, -2.00; P = 0.006) and lower corneal sensitivity (MD 12.40; 95% CI: 10.23, 14.56; P < 0.00001) at six months postoperatively. Conclusions In conclusion

Wavefront-guided versus wavefront-optimized laser in situ keratomileusis: contralateral comparative study.

PubMed

Padmanabhan, Prema; Mrochen, Michael; Basuthkar, Subam; Viswanathan, Deepa; Joseph, Roy

2008-03-01

To compare the outcomes of wavefront-guided and wavefront-optimized treatment in fellow eyes of patients having laser in situ keratomileusis (LASIK) for myopia. Medical and Vision Research Foundation, Tamil Nadu, India. This prospective comparative study comprised 27 patients who had wavefront-guided LASIK in 1 eye and wavefront-optimized LASIK in the fellow eye. The Hansatome (Bausch & Lomb) was used to create a superior-hinged flap and the Allegretto laser (WaveLight Laser Technologie AG), for photoablation. The Allegretto wave analyzer was used to measure ocular wavefront aberrations and the Functional Acuity Contrast Test chart, to measure contrast sensitivity before and 1 month after LASIK. The refractive and visual outcomes and the changes in aberrations and contrast sensitivity were compared between the 2 treatment modalities. One month postoperatively, 92% of eyes in the wavefront-guided group and 85% in the wavefront-optimized group had uncorrected visual acuity of 20/20 or better; 93% and 89%, respectively, had a postoperative spherical equivalent refraction of +/-0.50 diopter. The differences between groups were not statistically significant. Wavefront-guided LASIK induced less change in 18 of 22 higher-order Zernike terms than wavefront-optimized LASIK, with the change in positive spherical aberration the only statistically significant one (P= .01). Contrast sensitivity improved at the low and middle spatial frequencies (not statistically significant) and worsened significantly at high spatial frequencies after wavefront-guided LASIK; there was a statistically significant worsening at all spatial frequencies after wavefront-optimized LASIK. Although both wavefront-guided and wavefront-optimized LASIK gave excellent refractive correction results, the former induced less higher-order aberrations and was associated with better contrast sensitivity.

Dynamic torsional misalignment of eyes during laser in-situ keratomileusis.

PubMed

Shajari, Mehdi; Bühren, Jens; Kohnen, Thomas

2016-05-01

To determine the amount and characteristics of dynamic torsional misalignment of eyes during excimer ablation in laser in-situ keratomileusis (LASIK). Retrospective trial for evaluation of dynamic intraoperative torsional misalignment of 179 eyes that underwent LASIK for correction of myopia and/or astigmatism. Patients were treated with the Keracor 217z excimer laser implementing 25 Hz dynamic eye tracker ACE 100 (both Technolas Perfect Vision, Munich, Germany). From dynamic torsional misalignments, temporal power spectra were obtained by Fourier analysis up to a frequency of 12.5 Hz and an amplitude of ±15° from initial torsional status (limited by the tracking system). The f90, f95, and f99 criteria were defined as the frequency below which 90 %, 95 %, and 99 % of misalignments occur. A Wilcoxon rank sum test was performed to detect differences of f90, f95, and f99 in groups' gender, age, and eye (if both eyes underwent surgery at same day). Multiple regression analysis (MRA) was performed to evaluate possible preoperative predictors of f90, f95, and f99. Fourier analysis showed a dominance of high-frequency, low-power dynamic torsional misalignment. Mean f95 threshold of rotational movements was 4.89±2.12 Hz (median 4.54, ranging from 0.44 to 9.23 Hz). Wilcoxon rank sum test showed no differences in f90, f95, and f99 between groups' gender, age, and eye. MRA revealed age, gender, and optical zone as preoperative predictors on intraoperative f90, f95, and f99. Dynamic intraoperative torsional misalignments of eyes undergoing LASIK are dominated by low-frequency (slow), high-power (large) movements, with 95 % being slower than 4.89Hz regarding the spectrum analyzed (0-12.5Hz, ±15°). Movements can be predicted preoperatively by eye treated, patients' gender, and age in pre-LASIK diagnostics.

Clinical outcomes of wavefront-guided laser in situ keratomileusis: 6-month follow-up.

PubMed

Aizawa, Daisuke; Shimizu, Kimiya; Komatsu, Mari; Ito, Misae; Suzuki, Masanobu; Ohno, Koji; Uozato, Hiroshi

2003-08-01

To evaluate the clinical outcomes 6 months after wavefront-guided laser in situ keratomileusis (LASIK) for myopia in Japan. Department of Ophthalmology, Sanno Hospital, Tokyo, Japan. This prospective study comprised 22 eyes of 12 patients treated with wavefront-guided LASIK who were available for evaluation at 6 months. The mean patient age was 31.2 years +/- 8.4 (SD) (range 23 to 50 years), and the mean preoperative spherical equivalent refraction was -7.30 +/- 2.72 diopters (D) (range -2.75 to -11.88 D). In all cases, preoperative wavefront analysis was performed with a Hartmann-Shack aberrometer and the Technolas 217z flying-spot excimer laser system (Bausch & Lomb) was used with 1.0 mm and 2.0 mm spot sizes and an active eye tracker with a 120 Hz tracking rate. The clinical outcomes of wavefront-guided LASIK were evaluated in terms of safety, efficacy, predictability, stability, complications, and preoperative and postoperative aberrations. At 6 months, 10 eyes had no change in best spectacle-correct visual acuity and 10 gained 1 or more lines. The safety index was 1.11 and the efficacy index, 0.82. Slight undercorrections were observed in highly myopic eyes. In all eyes, the postoperative refraction tended slightly toward myopia for 3 months and stabilized after that. No complication such as epithelial ingrowth, diffuse lamellar keratitis, or infection was observed. Comparison of the preoperative and postoperative aberrations showed that 2nd-order aberrations decreased and higher-order aberrations increased. In the 3rd order, aberrations increased in the high-myopia group (-6.0 D or worse) and decreased in the low to moderate-myopia group (better than -6.0 D). Wavefront-guided LASIK was a good option for refractive surgery, although a longer follow-up in a larger study is required.

Comparison of the femtosecond laser and mechanical microkeratome for flap cutting in LASIK.

PubMed

Xia, Li-Kun; Yu, Jie; Chai, Guang-Rui; Wang, Dang; Li, Yang

2015-01-01

To compare refractive results, higher-order aberrations (HOAs), contrast sensitivity and dry eye after laser in situ keratomileusis (LASIK) performed with a femtosecond laser versus a mechanical microkeratome for myopia and astigmatism. In this prospective, non-randomized study, 120 eyes with myopia received a LASIK surgery with the VisuMax femtosecond laser for flap cutting, and 120 eyes received a conventional LASIK surgery with a mechanical microkeratome. Flap thickness, visual acuity, manifest refraction, contrast sensitivity function (CSF) curves, HOAs and dry-eye were measured at 1wk; 1, 3, 6mo after surgery. At 6mo postoperatively, the mean central flap thickness in femtosecond laser procedure was 113.05±5.89 µm (attempted thickness 110 µm), and 148.36±21.24 µm (attempted thickness 140 µm) in mechanical microkeratome procedure. An uncorrected distance visual acuity (UDVA) of 4.9 or better was obtained in more than 98% of eyes treated by both methods, a gain in logMAR lines of corrected distance visual acuity (CDVA) occurred in more than 70% of eyes treated by both methods, and no eye lost ≥1 lines of CDVA in both groups. The difference of the mean UDVA and CDVA between two groups at any time post-surgery were not statistically significant (P>0.05). The postoperative changes of spherical equivalent occurred markedly during the first month in both groups. The total root mean square values of HOAs and spherical aberrations in the femtosecond treated eyes were markedly less than those in the microkeratome treated eyes during 6mo visit after surgery (P<0.01). The CSF values of the femtosecond treated eyes were also higher than those of the microkeratome treated eyes at all space frequency (P<0.01). The mean ocular surface disease index scores in both groups were increased at 1wk, and recovered to preoperative level at 1mo after surgery. The mean tear breakup time (TBUT) of the femtosecond treated eyes were markedly longer than those of the microkeratome

Comparison of the femtosecond laser and mechanical microkeratome for flap cutting in LASIK

PubMed Central

Xia, Li-Kun; Yu, Jie; Chai, Guang-Rui; Wang, Dang; Li, Yang

2015-01-01

AIM To compare refractive results, higher-order aberrations (HOAs), contrast sensitivity and dry eye after laser in situ keratomileusis (LASIK) performed with a femtosecond laser versus a mechanical microkeratome for myopia and astigmatism. METHODS In this prospective, non-randomized study, 120 eyes with myopia received a LASIK surgery with the VisuMax femtosecond laser for flap cutting, and 120 eyes received a conventional LASIK surgery with a mechanical microkeratome. Flap thickness, visual acuity, manifest refraction, contrast sensitivity function (CSF) curves, HOAs and dry-eye were measured at 1wk; 1, 3, 6mo after surgery. RESULTS At 6mo postoperatively, the mean central flap thickness in femtosecond laser procedure was 113.05±5.89 µm (attempted thickness 110 µm), and 148.36±21.24 µm (attempted thickness 140 µm) in mechanical microkeratome procedure. An uncorrected distance visual acuity (UDVA) of 4.9 or better was obtained in more than 98% of eyes treated by both methods, a gain in logMAR lines of corrected distance visual acuity (CDVA) occurred in more than 70% of eyes treated by both methods, and no eye lost ≥1 lines of CDVA in both groups. The difference of the mean UDVA and CDVA between two groups at any time post-surgery were not statistically significant (P>0.05). The postoperative changes of spherical equivalent occurred markedly during the first month in both groups. The total root mean square values of HOAs and spherical aberrations in the femtosecond treated eyes were markedly less than those in the microkeratome treated eyes during 6mo visit after surgery (P<0.01). The CSF values of the femtosecond treated eyes were also higher than those of the microkeratome treated eyes at all space frequency (P<0.01). The mean ocular surface disease index scores in both groups were increased at 1wk, and recovered to preoperative level at 1mo after surgery. The mean tear breakup time (TBUT) of the femtosecond treated eyes were markedly longer than those of

Identification of the Infection Source of an Outbreak of Mycobacterium Chelonae Keratitis After Laser in Situ Keratomileusis.

PubMed

Nascimento, Heloisa; Viana-Niero, Cristina; Nogueira, Christiane Lourenço; Martins Bispo, Paulo José; Pinto, Fernando; de Paula Pereira Uzam, Camila; Matsumoto, Cristianne Kayoko; Oliveira Machado, Antônia Maria; Leão, Sylvia Cardoso; Höfling-Lima, Ana Luisa; de Freitas, Denise

2018-01-01

Nontuberculous mycobacteria keratitis is a rare but challenging complication of laser in situ keratomileusis (LASIK). This study was conducted to determine the source(s) of infection in a cluster of cases of keratitis after LASIK and to describe this outbreak and patients' outcomes. In this retrospective, case series, single-center study, 86 patients were included who underwent LASIK or photorefractive keratectomy between December 2011 and February 2012. Corneal scrapes from the affected eyes, samples of tap and distilled water, water from the reservoir of the distilling equipment, steamer, and autoclave cassette; antiseptic and anesthetic solutions and surgical instrument imprints were cultivated in liquid and on solid media. Gram-negative bacteria and yeasts were identified using automated systems and mycobacteria by polymerase chain reaction-restriction enzyme analysis of the hsp65 gene (PRA-hsp65) and DNA sequencing. Mycobacterial isolates were typed by pulsed-field gel electrophoresis. The cases and outcomes are described. The main outcome measure was identification of the source(s) of the mycobacterial infections. Eight (15 eyes) of 86 patients (172 eyes) who underwent LASIK developed infections postoperatively; no patients who underwent photorefractive keratectomy developed infections. Mycobacterium chelonae was isolated from 4 eyes. The distilled water collected in the surgical facility contained the same M. chelonae strain isolated from the patients' eyes. Different gram-negative bacteria and yeasts were isolated from samples collected at the clinic but not from the patients' eyes. Tap water distilled locally in surgical facilities may be a source of infection after ocular surgery and its use should be avoided.

The Aviation Accident Experience of Civilian Airmen With Refractive Surgery

DTIC Science & Technology

2002-06-01

such as photorefractive keratec- tomy (PRK) and laser-assisted in situ keratomileusis ( LASIK ), are being performed on a rapidly growing number of...stable, healing is complete, and no glare intolerance is present (4). RK, PRK, and LASIK procedures are similar only in that the goal is to improve...called photoablation, which utilizes the excimer laser to vaporize the cornea’s outer tissue. LASIK uses a specially designed surgical scalpel

Chronic dry eye in PRK and LASIK: manifestations, incidence and predictive factors

PubMed Central

Bower, Kraig S.; Sia, Rose K.; Ryan, Denise S.; Mines, Michael J.; Dartt, Darlene A.

2017-01-01

Purpose To evaluate dry eye manifestations following photorefractive keratectomy (PRK) and laser in situ keratomileusis (LASIK) and determine the incidence and predictive factors of chronic dry eye using a set of dry eye criteria. Setting Walter Reed Army Medical Center, Washington, DC, USA Methods This is a prospective non-randomized clinical study of 143 active duty U.S. Army personnel aged 29.9±5.2 years with myopia or myopic astigmatism (manifest spherical equivalent −3.83±1.96 diopters) undergoing either PRK or LASIK. Dry eye evaluation was performed pre- and postoperatively. Main outcome measures included dry eye manifestations, incidence, and predictive factors of chronic dry eye. Results Schirmer scores, corneal sensitivity, ocular surface staining, surface regularity index (SRI), and responses to dry eye questionnaire significantly changed over time after PRK. After LASIK, significant changes were observed in tear breakup time, corneal sensitivity, ocular surface staining, and responses to questionnaire. At twelve months postoperatively, 5.0% of PRK and 0.8% of LASIK participants developed chronic dry eye. Regression analysis showed preoperatively lower Schirmer score will significantly influence development of chronic dry eye after PRK whereas preoperatively lower Schirmer score or higher ocular surface staining score will significantly influence the occurrence of chronic dry eye after LASIK. Conclusions Chronic dry eye is uncommon after PRK and LASIK. Ocular surface and tear film characteristics during preoperative examination may help predict chronic dry eye development in PRK and LASIK. PMID:26796443

Satisfactory clinical outcome following delayed repositioning of a traumatic post-LASIK flap with dislocation and shrinkage managed by irrigation, stretching, and debridement.

PubMed

Xu, Ye-Sheng; Xie, Wen-Jia; Yao, Yu-Feng

2017-06-01

To report surgical management and favorable outcome in a case with delayed repair of traumatic laser in situ keratomileusis (LASIK) flap dislocation with shrinkage and folds. A 30-year-old man with a five-year history of bilateral LASIK experienced blunt trauma to his right eye followed by decreased vision for 5 weeks. The surgical management included initially softening the flap by irrigation with balanced salt solution (BSS). The shrinkage folds were carefully and gently stretched by scraping with a 26-gauge cannula accompanied by BSS irrigation. All of the epithelial ingrowth on the flap inner surface and on the bed was thoroughly debrided by scraping and irrigation. After the flap was repositioned to match its original margin, a soft bandage contact lens was placed. At his initial visit, slit-lamp microscopy and optical coherence tomography (OCT) showed shrinkage of the LASIK flap with an elevated margin approximately 3 mm above the original position. The flap covered half of the pupil and had multiple horizontal folds. Two months after surgery, the flap remained well positioned with only faint streaks in the anterior stroma. The uncorrected visual acuity of the right eye was 20/20 with a manifest refraction of Plano. For delayed repair of traumatically dislocated LASIK flaps, sufficient softening by BSS, stretching the shrinkage folds, and thorough debridement of ingrowth epithelium enable resetting the flap and provide satisfactory results.

Lasik eye surgery - discharge

MedlinePlus

... Technique. In: Mannis MJ, Holland EJ, eds. Cornea . 4th ed. Philadelphia, PA: Elsevier; 2017:chap 166. Sierra ... LASIK. In: Yanoff M, Duker JS, eds. Ophthalmology . 4th ed. Philadelphia, PA: Elsevier Saunders; 2014:chap 3. ...

Nonarteritic ischemic optic neuropathy secondary to severe ocular hypertension masked by interface fluid in a post-LASIK eye.

PubMed

Pham, Mai T; Peck, Rachel E; Dobbins, Kendall R B

2013-06-01

We report a case of ischemic optic neuropathy arising from elevated intraocular pressure (IOP) masked by interface fluid in a post-laser in situ keratomileusis (LASIK) eye. A 51-year-old man, who had had LASIK 6 years prior to presentation, sustained blunt trauma to the left eye that resulted in a hyphema and ocular hypertension. Elevated IOP resulted in accumulation of fluid in the stromal bed-LASIK flap interface, leading to underestimation of IOP when measured centrally over the flap. After days of unrecognized ocular hypertension, ischemic optic neuropathy developed. To our knowledge, this is the first reported case of ischemic optic neuropathy resulting from underestimated IOP measurements in a post-LASIK patient. It highlights the inaccuracy of IOP measurements in post-LASIK eyes and a vision-threatening potential complication. No author has a financial or proprietary interest in any material or method mentioned. Copyright © 2013 ASCRS and ESCRS. Published by Elsevier Inc. All rights reserved.

Outcomes of presbyopia-correcting intraocular lenses after laser in situ keratomileusis.

PubMed

Chow, Sharon S W; Chan, Tommy C Y; Ng, Alex L K; Kwok, Alvin K H

2018-03-28

Laser in situ keratomileusis (LASIK) is the most common refractive surgery in young patients, which aims at providing a clear distance vision without the use of spectacles. With time, these patients develop symptomatic cataract, which affects activities of daily living, and to improve visual acuity, intraocular lens (IOL) implantation can be considered. In post-myopic LASIK patients, to allow continuation of spectacle independence, the implantation of presbyopia-correcting IOLs is a suitable option. The purpose of this retrospective case series is to report the visual outcome and quality in post-myopic LASIK eyes after the implantation of AT LISA tri839MP IOL. Twenty eyes of 13 patients with history of myopic LASIK within 20 years underwent phacoemulsification by one single surgeon. All eyes were implanted with AT LISA tri839PMP IOL, and their outcomes were evaluated at 6 months postoperation. The mean postoperative uncorrected distance visual acuity (VA) is 0.28 ± 0.29, while the corrected distance VA is 0.06 ± 0.14. The mean postoperative uncorrected near VA is 0.02 ± 0.05, while the corrected near VA is 0.01 ± 0.02. The mean postoperative manifest refraction spherical equivalent (SE) is - 0.92 ± 0.76D. There is a statistically significant difference between the preoperative and postoperative refraction (p = 0.02), which shows a postoperative myopic shift. There is also a statistically significant difference between the mean targeted SE and postoperative manifest refraction SE (p = 0.00). Only one out of 20 eyes (5%) reported halo and glare symptoms. Ten out of 20 eyes (50%) are able to achieve spectacles independence. In conclusion, in post-myopic LASIK eyes, AT LISA tri839MP provides a good visual outcome at both near and distance, but is more predictable at near than at distance. There is a myopic shift in the postoperative SE. Visual quality is satisfactory and has not been exacerbated. Most patients can remain to be

Oral Omega-3 Fatty Acid Supplementation for Laser In Situ Keratomileusis-Associated Dry Eye.

PubMed

Goyal, Parul; Jain, Arun K; Malhotra, Chintan

2017-02-01

To determine the effect of oral omega-3 fatty acid (ω3FA) supplementation in laser in situ keratomileusis (LASIK)-associated dry eye. In this prospective, open-label study, patients undergoing LASIK were randomized to receive either 1.2 g/d of a triglyceride formulation of oral ω3FA (treatment group) or 400 mg/d vitamin E (control group) for 1 week before and continued for 12 weeks after surgery. Ocular surface disease index, tear breakup time, ocular surface staining, and Schirmer scores were evaluated and compared preoperatively and at 3 months after LASIK. The study included 30 patients in each group. All parameters were comparable at baseline. Ocular surface disease index scores increased comparably in both groups (1.9 ± 0.6 increase in the treatment group; 2.8 ± 0.5 in the control group) (P = 0.267). Compared with baseline levels, tear breakup time decreased significantly (P < 0.01) but comparably in both treatment (-2.3 ± 0.4 seconds decrease) and control (-3.5 ± 0.7 seconds decrease) groups (P = 0.105). More eyes in the control group (43.4%) had conjunctival staining with Lissamine green at 3 months compared with the treatment group (14%) (P = 0.009). The Schirmer score at 3 months was higher (P = 0.003) in the treatment group (30.5 ± 0.90 mm) than in the control group (25.7 ± 1.3 mm) with a increase of 5.9 ± 1.3 mm from baseline in the treatment group and a decrease of 1.5 ± 1.2 mm in the control group. Supplementation with ω3FA in patients undergoing LASIK had a positive influence on tear secretion, whereas tear film stability remained unaffected when compared with the control group.

Early changes in ocular surface and tear inflammatory mediators after small-incision lenticule extraction and femtosecond laser-assisted laser in situ keratomileusis.

PubMed

Gao, Shaohui; Li, Saiqun; Liu, Liangping; Wang, Yong; Ding, Hui; Li, Lili; Zhong, Xingwu

2014-01-01

To characterize the early ocular-surface changes or tear inflammatory-mediators levels following small-incision lenticule extraction (ReLEx smile) and femtosecond laser-assisted laser in situ keratomileusis (FS-LASIK). Forty-seven myopic subjects were recruited for this prospective study. Fifteen underwent ReLEx smile and thirty-two underwent FS-LASIK. Corneal fluorescein (FL) staining, tear break-up time (TBUT), Schirmer I test (SIT), ocular surface disease index (OSDI) and central corneal sensitivity were evaluated in all participants. Tears were collected and analyzed for interleukin-6 (IL-6), tumor necrosis factor-α (TNF-α), nerve growth factor (NGF) and intercellular adhesion molecule-1 (ICAM-1) levels using multiplex magnetic beads. All measurements were preformed preoperatively and 1 day, 1 week, 1 month and 3 months postoperatively. FL scores in ReLEx smile group were lower than those of FS-LASIK group 1 week postoperatively (P = 0.010). Compared to the FS-LASIK group, longer TBUT were observed in ReLEx smile group 1 month (P = 0.029) and 3 months (P = 0.045) postoperatively. No significant differences were found in tear secretion for the two groups (P>0.05). OSDI scores were higher in FS-LASIK group 1 month after surgery (P = 0.020). Higher central corneal sensitivity was observed in ReLEx smile group 1 week, 1 month and 3 months (P<0.05) postoperatively. Compared to FS-LASIK group, lower and faster recovery of IL-6 and NGF levels in tears was observed in ReLEx smile group postoperatively (P<0.05). Tears TNF-α and ICAM-1 concentrations were not significantly different between the two groups at any follow-up time (P>0.05). Moreover, IL-6 and NGF levels correlated with ocular surface changes after ReLEx smile or FS-LASIK. In the early postoperative period, ReLEx smile results in milder ocular surface changes than FS-LASIK. Furthermore, the tear inflammatory mediators IL-6 and NGF may play a crucial role in the ocular surface healing process following Re

Patient-reported outcomes 5 years after laser in situ keratomileusis.

PubMed

Schallhorn, Steven C; Venter, Jan A; Teenan, David; Hannan, Stephen J; Hettinger, Keith A; Pelouskova, Martina; Schallhorn, Julie M

2016-06-01

To assess vision-related, quality-of-life outcomes 5 years after laser in situ keratomileusis (LASIK) and determine factors predictive of patient satisfaction. Optical Express, Glasgow, Scotland. Retrospective case series. Data from patients who had attended a clinical examination 5 years after LASIK were analyzed. All treatments were performed using the Visx Star S4 IR excimer laser. Patient-reported satisfaction, the effect of eyesight on various activities, visual phenomena, and ocular discomfort were evaluated 5 years postoperatively. Multivariate regression analysis was performed to determine factors affecting patient satisfaction. The study comprised 2530 patients (4937 eyes) who had LASIK. The mean age at the time of surgery was 42.4 years ± 12.5 (SD), and the preoperative manifest spherical equivalent ranged from -11.0 diopters (D) to +4.88 D. Five years postoperatively, 79.3% of eyes were within ±0.50 D of emmetropia and 77.7% of eyes achieved monocular uncorrected distance visual acuity (UDVA) and 90.6% of eyes achieved binocular UDVA of 20/20 or better. Of the patients, 91.0% said they were satisfied with their vision and 94.9% did not wear distance correction. Less than 2.0% of patients noticed visual phenomena, even with spectacle correction. Major predictors of patient satisfaction 5 years postoperatively were postoperative binocular UDVA (37.6% variance explained by regression model), visual phenomena (relative contribution of 15.0%), preoperative and postoperative sphere and their interactions (11.6%), and eyesight-related difficulties with various activities such as night driving, outdoor activities, and reading (10.2%). Patient-reported quality-of-life and satisfaction rates remained high 5 years after LASIK. Uncorrected vision was the strongest predictor of satisfaction. Dr. S.C. Schallhorn is a consultant to Abbott Medical Optics, Inc., Zeiss Meditec AG, and Autofocus Inc. and a global medical director for Optical Express. No other

Effects of laser in situ keratomileusis on mental health-related quality of life.

PubMed

Tounaka-Fujii, Kaoru; Yuki, Kenya; Negishi, Kazuno; Toda, Ikuko; Abe, Takayuki; Kouyama, Keisuke; Tsubota, Kazuo

2016-01-01

The aims of our study were to investigate whether laser in situ keratomileusis (LASIK) improves health-related quality of life (HRQoL) and to identify factors that affect postoperative HRQoL. A total of 213 Japanese patients who underwent primary LASIK were analyzed in this study. The average age of patients was 35.0±9.4 years. The subjects were asked to answer questions regarding subjective quality of vision, satisfaction, and quality of life (using the Japanese version of 36-Item Short Form Health Survey Version 2) at three time points: before LASIK, 1 month after LASIK, and 6 months after LASIK. Longitudinal changes over 6 months in the outputs of mental component summary (MCS) score and the physical component summary (PCS) score from the 36-Item Short Form Health Survey Version 2 questionnaire were compared between time points using a linear mixed-effects model. Delta MCS and PCS were calculated by subtracting the postoperative score (1 month after LASIK) from the preoperative score. Preoperative and postoperative factors associated with a change in the MCS score or PCS score were evaluated via a linear regression model. The preoperative MCS score was 51.0±9.4 and increased to 52.0±9.8 and 51.5±9.6 at 1 month and 6 months after LASIK, respectively, and the trend for the change from baseline in MCS through 6 months was significant ( P =0.03). PCS score did not change following LASIK. Delta MCS was significantly negatively associated with preoperative spherical equivalent, axial length, and postoperative quality of vision, after adjusting for potential confounding factors. Mental HRQoL is not lost with LASIK, and LASIK may improve mental HRQoL. Preoperative axial length may predict postoperative mental HRQoL.

Effects of laser in situ keratomileusis on mental health-related quality of life

PubMed Central

Tounaka-Fujii, Kaoru; Yuki, Kenya; Negishi, Kazuno; Toda, Ikuko; Abe, Takayuki; Kouyama, Keisuke; Tsubota, Kazuo

2016-01-01

Purpose The aims of our study were to investigate whether laser in situ keratomileusis (LASIK) improves health-related quality of life (HRQoL) and to identify factors that affect postoperative HRQoL. Materials and methods A total of 213 Japanese patients who underwent primary LASIK were analyzed in this study. The average age of patients was 35.0±9.4 years. The subjects were asked to answer questions regarding subjective quality of vision, satisfaction, and quality of life (using the Japanese version of 36-Item Short Form Health Survey Version 2) at three time points: before LASIK, 1 month after LASIK, and 6 months after LASIK. Longitudinal changes over 6 months in the outputs of mental component summary (MCS) score and the physical component summary (PCS) score from the 36-Item Short Form Health Survey Version 2 questionnaire were compared between time points using a linear mixed-effects model. Delta MCS and PCS were calculated by subtracting the postoperative score (1 month after LASIK) from the preoperative score. Preoperative and postoperative factors associated with a change in the MCS score or PCS score were evaluated via a linear regression model. Results The preoperative MCS score was 51.0±9.4 and increased to 52.0±9.8 and 51.5±9.6 at 1 month and 6 months after LASIK, respectively, and the trend for the change from baseline in MCS through 6 months was significant (P=0.03). PCS score did not change following LASIK. Delta MCS was significantly negatively associated with preoperative spherical equivalent, axial length, and postoperative quality of vision, after adjusting for potential confounding factors. Conclusion Mental HRQoL is not lost with LASIK, and LASIK may improve mental HRQoL. Preoperative axial length may predict postoperative mental HRQoL. PMID:27713617

Intelligent Planning for Laser Refractive Surgeries

NASA Astrophysics Data System (ADS)

Wang, Wei; Yue, Yong; Elsheikh, Ahmed; Bao, Fangjun

2018-02-01

Refractive error is one of leading ophthalmic diseases for both genders all over the world. Laser refractive correction surgery, e.g., laser in-situ keratomileusis (LASIK), has been commonly used worldwide. The prediction of surgical parameters, e.g., corneal ablation depth, depends on the doctor’s experience, theoretical formula and surgery reference manual in the preoperative diagnosis. The error of prediction may present a potential surgical risk and complication. Being aware of the surgery parameters is important because these can be used to estimate a patient’s post-operative visual quality and help the surgeon plan a suitable treatment. Therefore, in this paper we discuss data mining techniques that can be utilized for the prediction of laser refractive correction surgery parameters. It can provide the surgeon with a reference for possible surgical parameters and outcomes of the patient before the laser refractive correction surgery.

Outcomes of laser in situ keratomileusis and photorefractive keratectomy in patients taking isotretinoin.

PubMed

Ortega-Usobiaga, Julio; Llovet-Osuna, Fernando; Djodeyre, Mohammad Reza; Bilbao-Calabuig, Rafael; González-López, Félix; Llovet-Rausell, Andrea; Druchkiv, Vasyl

2018-05-14

To determine the functional outcomes of laser in situ keratomileusis (LASIK) and photorefractive keratectomy (PRK) in patients taking isotretinoin, which is contraindicated for these procedures. Multicentre, retrospective, interventional case series METHODS: All patients taking isotretinoin who underwent LASIK or PRK from January 2003 to September 2017 were included (group 1). Patients were compared with those undergoing LASIK or PRK who had taken isotretinoin previously but not in the previous 6 months (group 2). Patients were included consecutively. A total of 113 patients (219 eyes) were included. No significant intraoperative or postoperative complications were found. There were no significant differences between the groups in terms of visual acuity, postoperative spherical equivalent, efficacy index, predictability, or safety index. When only PRK patients were taken into account, the efficacy index (p: 0.017), postoperative sphere (p: 0.041), and postoperative astigmatism (p<0.001) were better in group 2, although the difference was not clinically relevant. In our experience, LASIK and PRK can be performed effectively and safely in selected patients taking isotretinoin. The absolute exclusion of certain systemic medications should be reconsidered. Copyright © 2018 Elsevier Inc. All rights reserved.

One-year eye-to-eye comparison of wavefront-guided versus wavefront-optimized laser in situ keratomileusis in hyperopes

PubMed Central

Sáles, Christopher S; Manche, Edward E

2014-01-01

Background To compare wavefront (WF)-guided and WF-optimized laser in situ keratomileusis (LASIK) in hyperopes with respect to the parameters of safety, efficacy, predictability, refractive error, uncorrected distance visual acuity, corrected distance visual acuity, contrast sensitivity, and higher order aberrations. Methods Twenty-two eyes of eleven participants with hyperopia with or without astigmatism were prospectively randomized to receive WF-guided LASIK with the VISX CustomVue S4 IR or WF-optimized LASIK with the WaveLight Allegretto Eye-Q 400 Hz. LASIK flaps were created using the 150-kHz IntraLase iFS. Evaluations included measurement of uncorrected distance visual acuity, corrected distance visual acuity, <5% and <25% contrast sensitivity, and WF aberrometry. Patients also completed a questionnaire detailing symptoms on a quantitative grading scale. Results There were no statistically significant differences between the groups for any of the variables studied after 12 months of follow-up (all P>0.05). Conclusion This comparative case series of 11 subjects with hyperopia showed that WF-guided and WF-optimized LASIK had similar clinical outcomes at 12 months. PMID:25419115

[Static and dynamic contrast sensitivity of myopic eyes before and after laser in situ keratomileusis].

PubMed

Liu, Xiao-wei; Pang, Guo-xiang; Liu, Xi-pu; Jiang, Ru-xin; Jin, Yu-mei; Sun, Yu-min; Wang, Zhong-hai

2003-10-01

To evaluate the static and dynamic contrast sensitivity changes in myopic patients before and after laser in situ keratomileusis (LASIK). Seventy-three eyes in 37 patients with myopia (with or without astigmatism) who received LASIK were tested for static and dynamic contrast sensitivities using the METRO VISION MON ELEC I system at 0.7, 1.4, 2.7, 5.5, 11, and 22 cpd and cps prior to LASIK, and at one-, three-, and six-month intervals after LASIK. All eyes gained naked visual acuity of more than 0.5 after LASIK. The contrast sensitivity was depressed at all frequencies 1 month after LASIK, as compared to one week prior to LASIK. The depression at 2.7, 5.5, 11 (P < 0.01) and 22 cpd (P < 0.05) was statistically significant for static contrast sensitivity, and also at 5.5 (P < 0.01) and 11 cps (P < 0.05) for dynamic contrast sensitivity. Myopic eyes between 6.25 D and 14.0 D, and astigmatic eyes 2 DC and more, suffered more static and dynamic contrast sensitivity depression than the myopic eyes between 1.25 D and 6.00 D and astigmatic eyes less than 2 DC. Contrast sensitivities were improved and exceeded preoperative levels 3 months after LASIK, and improved even more 6 months after LASIK. All sequences were statistically significant for static contrast sensitivity (P < 0.01), while only 2.7, 5.5, and 11 cps were statistically significant for dynamic contrast sensitivity (P < 0.01). The astigmatic eyes 2 DC and more showed less improvement, even below the preoperative level at 1.4 cps of dynamic contrast sensitivity. While temporary depression of contrast sensitivity for myopic eyes after LASIK was seen, contrast sensitivity soon returned to exceed preoperative levels at 3 months after LASIK, while improving even more 6 months after LASIK.

Laser in situ keratomileusis enhancements with the Ziemer FEMTO LDV femtosecond laser following previous LASIK treatments.

PubMed

Pietilä, Juhani; Huhtala, Anne; Mäkinen, Petri; Uusitalo, Hannu

2013-02-01

The aim of this paper is to present the accuracy, predictability, and safety outcomes of LASIK enhancements performed with the FEMTO LDV femtosecond laser (Ziemer Ophthalmic Systems, Port, Switzerland) and the Allegretto Wave Concerto 500 Hz excimer laser (Wavelight AG, Erlangen, Germany), following previous LASIK treatments. FEMTO LDV was used for flap creation in 85 previously LASIK-treated eyes of 62 patients. The intended flap thickness was 90 μm in 81 eyes and 140 μm in 4 eyes. The size of the suction ring was 9.0 mm in 72 eyes and 9.5 mm in 13 eyes. Flap dimensions were measured and correlated to preoperative characteristics. With the intended flap thickness of 90 μm in previously LASIK-treated eyes, the actual flap thickness was 90.2 ± 6.6 μm (range 80-122), and the flap diameter was 9.2 ± 0.2 mm (range 8.7-9.9). The mean hinge length was 4.0 ± 0.2 mm (range 3.0-4.8). Flap thickness correlated positively with patient age and hinge length. Complications were reported in 12 eyes (14.1 %). Most of the complications were very mild, and none of them prevented further refractive laser treatment. One eye lost two Snellen lines of best spectacle-corrected visual acuity. Femtosecond LASIK enhancement is warranted only in rare cases. Surgical experience is needed and special caution must be practiced. For cases of a primary free cap, femtosecond LASIK is not recommended.

Corneal Densitometry as a Tool to Measure Epithelial Ingrowth After Laser In Situ Keratomileusis.

PubMed

Adran, Daniel; Vaillancourt, Louis; Harissi-Dagher, Mona; Kruh, Jonathan N; Syed, Zeba A; Robinson, Steven; Melki, Samir

2017-04-01

This study evaluates the correlation between corneal densitometry and epithelial ingrowth (EI) after laser in situ keratomileusis (LASIK). Corneal densitometry of 3 patients who developed EI after LASIK was measured with the Oculus Pentacam. Corneal densitometry readings of each patient were obtained preoperatively and postoperatively after ingrowth was discovered. Densitometry was recorded at the central nest of opacity and at the leading edges of EI. For all patients, the most severe stages of EI observed on slit-lamp photographs correlated with the highest densitometry readings, with peak densitometry ranging from 73.3 to 95.1. These values were much higher than preoperative densitometry readings, which ranged from 21.8 to 27.2. In 2 cases, the Pentacam densitometry map revealed progression of EI toward the visual axis that was only faintly detectable or not detectable at all on the corresponding slit-lamp photographs. Corneal densitometry seems to be an objective measure of the severity and progression of EI after LASIK.

Femtosecond Laser in situ Keratomileusis Flap Creation in Narrow Palpebral Fissure Eyes without Suction.

PubMed

Chang, John S M; Law, Antony K P; Ng, Jack C M; Cheng, May S Y

2017-01-01

To evaluate a surgical technique used in eyes with narrow palpebral fissure undergoing femtosecond laser flap creation without suction during laser in situ keratomileusis (LASIK). All data of 2 patient groups were collected through chart review. Group 1 consisted of 6 eyes with narrow palpebral fissure in which the suction ring was manually fixated and femtosecond laser was applied accordingly. Thirty comparison cases were randomly drawn from among eyes that underwent a standard LASIK procedure matched for age and preoperative refraction (group 2). Only 1 eye of each patient was selected to compare the refractive and visual outcomes between groups. In all group 1 eyes, the flaps were created successfully with manual fixation of the suction ring without suction. No eyes lost 2 or more lines of vision. No significant difference was found in the safety and refractive outcomes between groups. Manual fixation of the suction ring in eyes with narrow palpebral fissure without suction was feasible for flap creation during LASIK.

Study on the transverse chromatic aberration of the individual eye model after LASIK refractive surgery

NASA Astrophysics Data System (ADS)

Zhang, Mei; Wang, Zhao-Qi; Wang, Yan; Zuo, Tong

2010-10-01

The aim of this research is to study the properties of the transverse chromatic aberration (TCA) after the LASIK refractive surgery based on the individual eye model involving the angle between visual axis and optical axis. According to the measurements of the corneal surfaces, the optical axis lengths and the wavefront aberrations, the individual eye models before and after LASIK refractive surgery are constructed for 15 eyes by using ZEMAX optic design software, while the angle between the visual axis and optical axis is calculated from the data of the anterior corneal surface. The constructed eye models are then used to investigate the variation of the TCA after the surgery. The statistical distributions of the magnitude of the foveal TCA for 15 eyes over the visible spectrum are provided. Finally, we investigate the influence of the TCA on the visual quality and compare the results with previous research. The TCA is an indispensable criterion to evaluate the performance of the refractive surgery. This research is very meaningful for the studies of not only foveal vision but also the peripheral vision.

Photorefractive keratectomy versus laser in situ keratomileusis for moderate to high myopia. A randomized prospective study.

PubMed

Hersh, P S; Brint, S F; Maloney, R K; Durrie, D S; Gordon, M; Michelson, M A; Thompson, V M; Berkeley, R B; Schein, O D; Steinert, R F

1998-08-01

This report presents the results of a randomized clinical trial of photorefractive keratectomy (PRK) and laser-assisted in situ keratomileusis (LASIK). A randomized, prospective multicenter clinical trial. A total of 220 eyes of 220 patients entered the study cohort: 105 randomized to PRK and 115 to LASIK. The mean preoperative manifest refraction spherical equivalent was -9.23 diopters (D) in the PRK group and -9.30 D in the LASIK group. All patients received a one-pass, multizone excimer laser ablation as part of either a PRK or LASIK procedure using the Summit Apex excimer laser. Attempted corrections ranged from 6.00 to 15.00 D. Data on uncorrected and spectacle-corrected visual acuity, predictability,and stability of refraction, corneal haze, and flap complications were analyzed. Patients were observed for up to 6 months. One day after surgery, 0 (0.0%) and 3 (4.5%) eyes in the PRK group saw 20/20 and 20/40 or better uncorrected, respectively, while 7 (10%) and 48 (68.6%) eyes in the LASIK group saw 20/20 and 20/40 or better, respectively. At 6 months after PRK, 13 (19.1%) and 45 (66.2%) eyes saw 20/20 and 20/40 or better, respectively, while after LASIK, 16 (26.2%) and 34 (55.7%) eyes saw 20/20 and 20/40 or better, respectively (odds ratio = 0.56 for likelihood of uncorrected visual acuity < 20/40 for PRK vs. LASIK, 95% confidence interval [CI] = 0.31-1.19). After PRK, 39 eyes (57.4%) were within 1.0 D of attempted correction compared with 24 eyes (40.7%) in the LASIK group (odds ratio = 0.50 for likelihood fo undercorrection 1.0 D for PRK vs. LASIK, 95% CI = 0.24-1.04); however, the standard deviation of the predictability was similar between groups: 1.01 D for PRK and 1.22 D for LASIK. From months 1 to 6, there was an average regression of 0.89 D in the PRK group and 0.55 D in the LASIK group. After PRK, eight eyes (11.8%) had a decrease in spectacle-corrected visual acuity of two Snellen lines or more; after LASIK, two eyes (3.2%) had a decrease of two

Laser in situ keratomileusis using optimized aspheric profiles and cyclotorsion control to treat compound myopic astigmatism with high cylinder.

PubMed

Alió, Jorge L; Plaza-Puche, Ana B; Martinez, Lorena M; Torky, Magda; Brenner, Luis F

2013-01-01

To evaluate the visual outcomes after laser in situ keratomileusis (LASIK) surgery to correct primary compound myopic astigmatism with high cylinder performed using a fast-repetition-rate excimer laser platform with optimized aspheric profiles and cyclotorsion control. Vissum Corporation and Division of Ophthalmology, Universidad Miguel Hernández, Alicante, Spain. Retrospective consecutive observational nonrandomized noncomparative case series. Eyes with primary compound myopic astigmatism and a cylinder power over 3.00 diopters (D) had uneventful LASIK with femtosecond flap creation and fast-repetition-rate excimer laser ablation with aspheric profiles and cyclotorsion control. Visual, refractive, and aberrometric outcomes were evaluated at the 6-month follow-up. The astigmatic correction was evaluated using the Alpins method and Assort software. The study enrolled 37 eyes (29 patients; age range 19 to 55 years). The significant reduction in refractive sphere and cylinder 3 months and 6 months postoperatively (P<.01) was associated with improved uncorrected distance visual acuity (P<.01). Eighty-seven percent of eyes had a spherical equivalent within ±0.50 D; 7.5% of eyes were retreated. There was no significant induction of higher-order aberrations (HOAs). The targeted and surgically induced astigmatism magnitudes were 3.23 D and 2.96 D, respectively, and the correction index was 0.91. The safety and efficacy indices were 1.05 and 0.95, respectively. Laser in situ keratomileusis for primary compound myopic astigmatism with high cylinder (>3.00 D) performed using a fast-repetition-rate excimer laser with optimized aspheric profiles and cyclotorsion control was safe, effective, and predictable and did not cause significant induction of HOAs. Copyright © 2012 ASCRS and ESCRS. Published by Elsevier Inc. All rights reserved.

Longitudinal Evaluation of Cornea With Swept-Source Optical Coherence Tomography and Scheimpflug Imaging Before and After Lasik

PubMed Central

Chan, Tommy C.Y.; Biswas, Sayantan; Yu, Marco; Jhanji, Vishal

2015-01-01

Abstract Swept-source optical coherence tomography (OCT) is the latest advancement in anterior segment imaging. There are limited data regarding its performance after laser in situ keratomileusis (LASIK). We compared the reliability of swept-source OCT and Scheimpflug imaging for evaluation of corneal parameters in refractive surgery candidates with myopia or myopic astigmatism. Three consecutive measurements were obtained preoperatively and 1 year postoperatively using swept-source OCT and Scheimpflug imaging. The study parameters included central corneal thickness (CCT), thinnest corneal thickness (TCT), keratometry at steep (Ks) and flat (Kf) axes, mean keratometry (Km), and, anterior and posterior best fit spheres (Ant and Post BFS). The main outcome measures included reliability of measurements before and after LASIK was evaluated using intraclass correlation coefficient (ICC) and reproducibility coefficients (RC). Association between the mean value of corneal parameters with age, spherical equivalent (SEQ), and residual bed thickness (RBT) and association of variance heterogeneity of corneal parameters and these covariates were analyzed. Twenty-six right eyes of 26 participants (mean age, 32.7 ± 6.9 yrs; mean SEQ, −6.27 ± 1.67 D) were included. Preoperatively, swept-source OCT demonstrated significantly higher ICC for Ks, CCT, TCT, and Post BFS (P ≤ 0.016), compared with Scheimpflug imaging. Swept-source OCT demonstrated significantly smaller RC values for CCT, TCT, and Post BFS (P ≤ 0.001). After LASIK, both devices had significant differences in measurements for all corneal parameters (P ≤ 0.015). Swept-source OCT demonstrated a significantly higher ICC and smaller RC for all measurements, compared with Scheimpflug imaging (P ≤ 0.001). Association of variance heterogeneity was only found in pre-LASIK Ant BFS and post-LASIK Post BFS for swept-source OCT, whereas significant association of variance heterogeneity was noted

Comparison of Sub-Bowman Keratoplasty Laser In situ Keratomileusis Flap Properties between Microkeratome and Femtosecond Laser.

PubMed

Fazel, Farhad; Ghoreishi, Mohammad; Ashtari, Alireza; Arefpour, Reza; Namgar, Mohammad

2017-01-01

Since thin and high-quality flaps produce more satisfactory surgical outcomes, flaps created by mechanical microkeratomes are more economical as compared with femtosecond lasers, and no Iranian study has concentrated laser in situ keratomileusis (LASIK) flap peculiarities between Moria Sub-Bowman keratoplasty (SBK) microkeratomes and LDV femtoseconds, the present study compares and contrasts them. This cross-sectional study was done on all patients who underwent LASIK surgery 1-month before this study. Thirty eyes were divided into per group. Flaps in the first group and second group were created, respectively, using Moria SBK microkeratome and LDV femtosecond laser. The other stages of LASIK were done equally in both groups. One month after surgery, the thickness of flaps was measured by anterior segment optical coherence tomography in five regions of flaps. Corneal anterior density was calculated and recorded 1-month after surgery using pentacam and by employing optical densitometry in a distance in the limit range of 0-6 mm from cornea center. Densitometry measurements were obtained and expressed in standardized grayscale units (GSUs). Postsurgery densitometry results reveal that anterior densities of cornea in limit range of 0-2 mm in groups of LDV femtosecond laser and Moria microkeratome are 21.35 ± 0.87 GSU and 22.85 ± 1.25 GSU, respectively. Accordingly, these two groups are significantly different in this regard ( P < 0.001). Moreover, anterior densities of the cornea in the limit range of 2-6 mm in these groups are 19.66 ± 0.99 GSU and 20.73 ± 1.24 GSU, respectively. Accordingly, these two groups are significantly different in this regard ( P = 0.04). There is a lower mean of flap thickness in the case of LDV femtosecond laser. Femtosecond laser method is greatly preferred as compared with Moria microkeratome because of greater homogeneity in flap thickness, smaller thickness, and lower density in optical zone.

Laser in situ keratomileusis for residual hyperopic astigmatism after conductive keratoplasty.

PubMed

Kymionis, George D; Aslanides, Ioannis M; Khoury, Aghlab N; Markomanolakis, Marinos M; Naoumidi, Tatiana; Pallikaris, loannis G

2004-01-01

To report a case of laser in situ keratomileusis (LASIK) in a patient with previous conductive keratoplasty. A 48-year-old man underwent conductive keratoplasty for low hyperopic astigmatism (manifest refraction OD: +2.25 -0.50 x 77 degrees; OS: +2.50 -0.50 x 105 degrees). Three months postoperatively, UCVA was 20/25 and BSCVA was 20/20 in both eyes; manifest refraction OD: -0.25 -0.75 x 110 degrees; OS: +0.75 -0.75 x 50 degrees. Sixteen months after the operation, regression of refractive outcome was (manifest) OD: +1.75 -1.25 x 90 degrees; OS: +2.50 -0.50 x 85 degrees; UCVA was 20/40 in the right eye and 20/63 in the left eye and BSCVA was 20/20 in both eyes. LASIK was performed for hyperopic regression in the left eye using an automated microkeratome (Alcon SKBM, 130-microm plate; Aesculap-Meditec MEL 70 excimer laser). LASIK was uneventful and no intraoperative or postoperative complications related to the previous conductive keratoplasty procedure or LASIK were observed. Three months after LASIK and 19 months after the initial conductive keratoplasty, the patient's left eye was emmetropic; UCVA was 20/20(-2), BSCVA was 20/20 and manifest refraction was +0.25 -0.25 x 35 degrees. There was a uniform increase in topographical steepening. Visual acuity, refraction and topographic findings remained unchanged at 6 months. Even though our experience is limited, treatment of hyperopia with LASIK in an eye with refractive regression following previous conductive keratoplasty resulted in a predicted refractive outcome, with no complications, and improvement in visual acuity at 6 months follow-up.

Satisfactory clinical outcome following delayed repositioning of a traumatic post-LASIK flap with dislocation and shrinkage managed by irrigation, stretching, and debridement*

PubMed Central

Xu, Ye-sheng; Xie, Wen-jia; Yao, Yu-feng

2017-01-01

Objective: To report surgical management and favorable outcome in a case with delayed repair of traumatic laser in situ keratomileusis (LASIK) flap dislocation with shrinkage and folds. Methods: A 30-year-old man with a five-year history of bilateral LASIK experienced blunt trauma to his right eye followed by decreased vision for 5 weeks. The surgical management included initially softening the flap by irrigation with balanced salt solution (BSS). The shrinkage folds were carefully and gently stretched by scraping with a 26-gauge cannula accompanied by BSS irrigation. All of the epithelial ingrowth on the flap inner surface and on the bed was thoroughly debrided by scraping and irrigation. After the flap was repositioned to match its original margin, a soft bandage contact lens was placed. Results: At his initial visit, slit-lamp microscopy and optical coherence tomography (OCT) showed shrinkage of the LASIK flap with an elevated margin approximately 3 mm above the original position. The flap covered half of the pupil and had multiple horizontal folds. Two months after surgery, the flap remained well positioned with only faint streaks in the anterior stroma. The uncorrected visual acuity of the right eye was 20/20 with a manifest refraction of Plano. Conclusions: For delayed repair of traumatically dislocated LASIK flaps, sufficient softening by BSS, stretching the shrinkage folds, and thorough debridement of ingrowth epithelium enable resetting the flap and provide satisfactory results. PMID:28585430

Functional outcome and patient satisfaction after laser in situ keratomileusis for correction of myopia and myopic astigmatism.

PubMed

Bamashmus, Mahfouth A; Hubaish, Khammash; Alawad, Mohammed; Alakhlee, Hisham

2015-01-01

The purpose was to evaluate subjective quality of vision and patient satisfaction after laser in situ keratomileusis (LASIK) for myopia and myopic astigmatism. A self-administered patient questionnaire consisting 29 items was prospectively administered to LASIK patients at the Yemen Magrabi Hospital. Seven scales covering specific aspects of the quality of vision were formulated including; global satisfaction; quality of uncorrected and corrected vision; quality of night vision; glare; daytime driving and; night driving. Main outcome measures were responses to individual questions and scale scores and correlations with clinical parameters. The scoring scale ranged from 1 (dissatisfied) to 3 (very satisfied) and was stratified in the following manner: 1-1.65 = dissatisfied; 1.66-2.33 = satisfied and; 2.33-3 = very satisfied. Data at 6 months postoperatively are reported. This study sample was comprised of 200 patients (122 females: 78 males) ranging in age from 18 to 46 years old. The preoperative myopic sphere was - 3.50 ± 1.70 D and myopic astigmatism was 0.90 ± 0.82 D. There were 96% of eyes within ± 1.00 D of the targeted correction. Postoperatively, the uncorrected visual acuity was 20/40 or better in 99% of eyes. The mean score for the overall satisfaction was 2.64 ± 0.8. A total of 98.5% of patients was satisfied or very satisfied with their surgery, 98.5% considered their main goal for surgery was achieved. Satisfaction with uncorrected vision was 2.5 ± 0.50. The main score for glare was 1.98 ± 0.7 at night. Night driving was rated more difficult preoperatively by 6.2%, whereas 79% had less difficulty driving at night. Patient satisfaction with uncorrected vision after LASIK for myopia and myopic astigmatism appears to be excellent and is related to the residual refractive error postoperatively.

Nd:YAG laser for epithelial ingrowth after laser in situ keratomileusis.

PubMed

Mohammed, Osama Ali; Mounir, Amr; Hassan, Amin Aboali; Alsmman, Alahmady Hamad; Mostafa, Engy Mohamed

2018-05-04

To evaluate the efficacy of neodymium:yttrium-aluminum-garnet (Nd:YAG) laser for treatment of epithelial ingrowth after laser in situ keratomileusis (LASIK). Fifty-eight patients with epithelial ingrowth presented to Sohag refractive center, Sohag, Egypt, between January 2015 and March 2017. Only 41 patients (18 females and 23 males, mean age: 33.4 years) involving 41 eyes were indicated for treatment by Nd:YAG laser as the rest of the eyes were only under observation. Patients with epithelial ingrowth were recognized at a mean of 6 months after primary LASIK procedure (range: 2-16 months). Four eyes had undergone previous LASIK enhancements. Four eyes had the epithelial ingrowth removed by flap lift and scrapping. The mean intensity of the spots used was 0.8 mJ with variable number of shots depending on the size and density of the epithelial ingrowth area. Twenty-eight eyes showed complete regression after one session, while the rest necessitated 2-3 sessions for complete resolution. Mean follow-up period was 8 months (range 5-12 months). Epithelial ingrowth was treated successfully in all 41 eyes. The uncorrected visual acuities were 20/20, and there was no evidence of recurrent epithelial ingrowth after 6 months with no complications reported. YAG laser is a simple, effective outpatient procedure for the management of epithelial ingrowth after LASIK.

Dry Eye Disease following Refractive Surgery: A 12-Month Follow-Up of SMILE versus FS-LASIK in High Myopia

PubMed Central

Wang, Bingjie; Chu, Renyuan; Dai, Jinhui; Qu, Xiaomei; Zhou, Hao

2015-01-01

Purpose. To compare dry eye disease following SMILE versus FS-LASIK. Design. Prospective, nonrandomised, observational study. Patients. 90 patients undergoing refractive surgery for myopia were included. 47 eyes underwent SMILE and 43 eyes underwent FS-LASIK. Methods. Evaluation of dry eye disease was conducted preoperatively and at 1, 3, 6, and 12 months postoperatively, using the Salisbury Eye Evaluation Questionnaire (SEEQ) and TBUT. Results. TBUT reduced following SMILE at 1 and 3 months (p < 0.001) and at 1, 3, and 6 months following FS-LASIK (p < 0.001). TBUT was greater following SMILE than FS-LASIK at 3, 6, and 12 months (p < 0.001, p < 0.001, and p = 0.009, resp.). SEEQ scores increased (greater symptoms) following SMILE at 1 month (p < 0.001) and 3 months (p = 0.003) and at 1, 3, and 6 months following FS-LASIK (p < 0.001). SMILE produced lower SEEQ scores (fewer symptoms) than FS-LASIK at 1, 3, and 6 months (p < 0.001). Conclusion. SMILE produces less dry eye disease than FS-LASIK at 6 months postoperatively but demonstrates similar degrees of dry eye disease at 12 months. PMID:26649190

Reliability of Pentacam HR Thickness Maps of the Entire Cornea in Normal, Post-Laser In Situ Keratomileusis, and Keratoconus Eyes.

PubMed

Xu, Zhe; Peng, Mei; Jiang, Jun; Yang, Chun; Zhu, Weigen; Lu, Fan; Shen, Meixiao

2016-02-01

To measure the repeatability and reproducibility of Pentacam HR system thickness maps for the entire cornea in normal, post-laser in situ keratomileusis (post-LASIK), and keratoconus (KC) eyes. Reliability study. Sixty normal subjects (60 eyes), 30 post-LASIK subjects (60 eyes), and 14 KC patients (27 eyes) were imaged with the Pentacam HR system by 2 well-trained operators. For pachymetry the cornea was divided into 4 zones: a central zone (2-mm diameter) and concentric pericentral zone (2-5 mm), transitional zone (5-7 mm), and peripheral zone (7-10 mm). The 3 concentric zones were subdivided into 8 sectors. Intraobserver repeatability and interobserver reproducibility of entire corneal thickness maps were tested by the repeatability and reproducibility coefficients, intraclass correlation coefficients, coefficient of variation, and 95% limits of agreement. From central to peripheral zones, the precision of corneal thickness measurements became gradually smaller. Central zone repeatability and reproducibility were the best in the normal, post-LASIK, and KC groups. The peripheral superior sectors showed poorer repeatability and reproducibility for all subjects. The intraobserver repeatability and interobserver reproducibility for all zones were ≤19.3 μm, ≤22.1 μm, and ≤20.7 μm, in the normal, post-LASIK, and KC groups, respectively. The intraobserver and interobserver coefficients of variation for all zones were ≤1.3%, ≤1.6%, and ≤1.6% for all 3 groups. Pentacam HR system pachymetry of the entire cornea provided good precision in normal, post-LASIK, and KC corneas. Thickness measurements in the peripheral cornea should be interpreted with caution in abnormal corneas after surgery or with diseases. Copyright © 2016 Elsevier Inc. All rights reserved.

Outcomes of Retreatment after Aborted Laser In Situ Keratomileusis due to Flap Complications

PubMed Central

Al-Mezaine, Hani S.; Al-Amro, Saleh A.; Al-Fadda, Abdulaziz; Al-Obeidan, Saleh

2011-01-01

Purpose: To determine the refractive outcomes and complications of retreatment after aborted primary laser in situ keratomileusis (LASIK) due to flap complications. Materials and Methods: This retrospective study evaluated 50 retreated eyes that had flap complications during primary LASIK at the Eye Consultants Center in Riyadh, Saudi Arabia. Data were analyzed for patients with at least 3 months follow-up post retreatment. Results: Thirty-three eyes of 31 consecutive patients with 3 months follow-up or later post retreatment were included. The primary LASIK was aborted due to incomplete flaps in 22 eyes (66.7%), buttonhole flaps in 7 eyes (21.2%), free partial flaps in 3 eyes (9.1%), and a free complete flap in 1 eye (3.0%). Twenty-two eyes (66.7%) were retreated with LASIK, and 11 eyes (33.3%) were retreated with surface ablation. The mean spherical equivalent (SE) was –0.23 ± 0.72 D, the mean astigmatism was –0.65 ± 0.89 D, and the mean loss of the best corrected visual acuity (BCVA) was 0.78 lines at the final postoperative visit. At the last postoperative visit, 20/30 or better BCVA was achieved in 90.1% of eyes that underwent retreatment with LASIK and in 91% of eyes that were retreated with surface ablation. There was no statistical difference in postoperative SE between eyes retreated with LASIK and eyes retreated with surface ablation (P = 0.610). There was no statistical difference in postoperative BCVA between eyes retreated with LASIK and those retreated with surface ablation (P = 0.756). There were no intraoperative complications and no eyes required a second retreatment. Conclusion: Creation of a flap after a previous intraoperative flap complication was not associated with any complications. The refractive outcomes of retreatment with LASIK or surface ablation were comparable and reasonably favorable. PMID:21887080

Outcomes of Retreatment after Aborted Laser In Situ Keratomileusis due to Flap Complications.

PubMed

Al-Mezaine, Hani S; Al-Amro, Saleh A; Al-Fadda, Abdulaziz; Al-Obeidan, Saleh

2011-07-01

To determine the refractive outcomes and complications of retreatment after aborted primary laser in situ keratomileusis (LASIK) due to flap complications. This retrospective study evaluated 50 retreated eyes that had flap complications during primary LASIK at the Eye Consultants Center in Riyadh, Saudi Arabia. Data were analyzed for patients with at least 3 months follow-up post retreatment. Thirty-three eyes of 31 consecutive patients with 3 months follow-up or later post retreatment were included. The primary LASIK was aborted due to incomplete flaps in 22 eyes (66.7%), buttonhole flaps in 7 eyes (21.2%), free partial flaps in 3 eyes (9.1%), and a free complete flap in 1 eye (3.0%). Twenty-two eyes (66.7%) were retreated with LASIK, and 11 eyes (33.3%) were retreated with surface ablation. The mean spherical equivalent (SE) was -0.23 ± 0.72 D, the mean astigmatism was -0.65 ± 0.89 D, and the mean loss of the best corrected visual acuity (BCVA) was 0.78 lines at the final postoperative visit. At the last postoperative visit, 20/30 or better BCVA was achieved in 90.1% of eyes that underwent retreatment with LASIK and in 91% of eyes that were retreated with surface ablation. There was no statistical difference in postoperative SE between eyes retreated with LASIK and eyes retreated with surface ablation (P = 0.610). There was no statistical difference in postoperative BCVA between eyes retreated with LASIK and those retreated with surface ablation (P = 0.756). There were no intraoperative complications and no eyes required a second retreatment. Creation of a flap after a previous intraoperative flap complication was not associated with any complications. The refractive outcomes of retreatment with LASIK or surface ablation were comparable and reasonably favorable.

Evaluation of transcutaneous electrical simulation to improve recovery from corneal hypoesthesia after LASIK.

PubMed

Ghaffariyeh, Alireza; Peyman, Alireza; Puyan, Sadollah; Honarpisheh, Nazafarin; Bagheri, Babak; Peyman, Mohammadreza

2009-08-01

To evaluate the efficacy, and safety of transcutaneous electrical stimulation (TES) to accelerate corneal nerve regeneration and improved recovery from corneal hypesthasia after laser-assisted in situ keratomileusis (LASIK). Khodadoust Eye Hospital, Shiraz, Fars, Iran This prospective, randomized, clinical study comprised 40 eyes of 20 patients scheduled to undergo bilateral LASIK. In each patient, one eye was randomly assigned to receive transcutaneous electrical stimulation (20 HZ) for 60 minutes, and the other eye allocated as control. Corneal sensitivity was measured using the Cochet-Bonnet esthesiometer in four areas outside and five areas inside the LASIK flap preoperatively, and at 1 day, 1 week, 1 month, and 3 months postoperatively. Best-corrected visual acuity and the incidence of adverse events were noted at each visit. For all four points outside the LASIK flap, normal corneal sensitivity was maintained throughout the study; no significant difference was found between the study eyes and the control eyes at these points (P > 0.05). All points within the LASIK flap except the point closest to the hinge demonstrated profound corneal hypoesthesia at 1 day, 1 week, and 1 month postoperatively, with no differences noted between the control and study eyes (P > 0.05). After 3 months, points within the flap had statistically significantly better corneal sensitivity in the study group than in the control group (P < 0.05). Transcutaneous electrical stimulation significantly improves corneal sensitivity at 3 months after LASIK. This may be due to accelerated corneal nerve regeneration by electrical stimulation.

Delayed onset Mycobacterium intracellulare keratitis after laser in situ keratomileusis: A case report and literature review.

PubMed

Ko, JaeSang; Kim, Se Kyung; Yong, Dong Eun; Kim, Tae-Im; Kim, Eung Kweon

2017-12-01

Infectious keratitis is a relatively uncommon but potentially sight-threatening complication of laser in situ keratomileusis (LASIK). Mycobacterial keratitis is usually regarded as late onset keratitis among post-LASIK keratitis. There has been no documented case of Mycobacterium intracellulare post-LASIK keratitis of a long-latent period. A 36-year-old man was referred to our out-patient clinic, for persistent corneal epithelial defect with intrastromal infiltration. He had undergone uneventful bilateral LASIK procedure 4 years before. He complained decreased vision, accompanied by ocular pain, photophobia, and redness in his left eye for 7 months. Lamellar keratectomy was taken using femtosecond laser. Bacterial culture with sequenced bacterial 16s ribosomal DNA confirmed the organism to be M intracellulare. After 3 months of administration of topical clarithromycin, amikacin, and moxifloxacin, the corneal epithelial defect was resolved and the infiltration was much improved. However, newly developed diffuse haziness with surrounding granular infiltration in the central cornea was noted. Drug toxicity was suspected and topical moxifloxacin was discontinued, resulting in resolution of the diffuse haze with infiltration. The patient was followed up regularly without medication thereafter and recurrence was not found for 7 years. This case presents the first case of M intracellulare keratitis after LASIK. LASIK surgeons should aware that post-LASIK keratitis can develop long after the operation and careful suspicion of infectious disease with meticulous diagnostic test is needed. Copyright © 2017 The Authors. Published by Wolters Kluwer Health, Inc. All rights reserved.

Management of post-LASIK dry eye: a multicenter randomized comparison of a new multi-ingredient artificial tear to carboxymethylcellulose

PubMed Central

Wallerstein, Avi; Jackson, W Bruce; Chambers, Jeffrey; Moezzi, Amir M; Lin, Hugh; Simmons, Peter A

2018-01-01

Purpose To compare the efficacy and safety of a preservative-free, multi-ingredient formulation of carboxymethylcellulose 0.5%, hyaluronic acid 0.1%, and organic osmolytes (CMC-HA), to preservative-free carboxymethylcellulose 0.5% (CMC) in the management of postoperative signs and symptoms of dry eye following laser-assisted in situ keratomileusis (LASIK). Methods This was a double-masked, randomized, parallel-group study conducted in 14 clinical centers in Canada and Australia. Subjects with no more than mild dry eye instilled CMC-HA or CMC for 90 days post-LASIK. Ocular Surface Disease Index© (OSDI; primary efficacy measure), corneal staining, tear break-up time (TBUT), Schirmer’s test, acceptability/tolerability surveys, and visual acuity were assessed at screening and days 2, 10, 30, 60, and 90 post-surgery. Safety analyses included all enrolled. Results A total of 148 subjects (CMC-HA, n=75; CMC, n=73) were enrolled and assigned to receive treatment, and 126 subjects completed the study without any protocol violations. Post-LASIK, dry eye signs/symptoms peaked at 10 days. OSDI scores for both groups returned to normal with no differences between treatment groups at day 90 (P=0.775). Corneal staining, Schirmer’s test, TBUT, and survey results were comparable. Higher mean improvements in uncorrected visual acuity were observed in the CMC-HA group at all study visits, reaching statistical significance at day 30 (P=0.013). Both treatments were well tolerated. Conclusion CMC-HA-containing artificial tears relieved post-LASIK ocular dryness as well as CMC alone, and demonstrated incremental benefit in uncorrected vision, with a favorable safety profile. Results support use of CMC-HA eye drops to reduce signs and symptoms of ocular dryness post-LASIK. PMID:29765198

Early Changes in Ocular Surface and Tear Inflammatory Mediators after Small-Incision Lenticule Extraction and Femtosecond Laser-Assisted Laser In Situ Keratomileusis

PubMed Central

Gao, Shaohui; Li, Saiqun; Liu, Liangping; Wang, Yong; Ding, Hui; Li, Lili; Zhong, Xingwu

2014-01-01

Purpose To characterize the early ocular-surface changes or tear inflammatory-mediators levels following small-incision lenticule extraction (ReLEx smile) and femtosecond laser-assisted laser in situ keratomileusis (FS-LASIK). Methods Forty-seven myopic subjects were recruited for this prospective study. Fifteen underwent ReLEx smile and thirty-two underwent FS-LASIK. Corneal fluorescein (FL) staining, tear break-up time (TBUT), Schirmer I test (SIT), ocular surface disease index (OSDI) and central corneal sensitivity were evaluated in all participants. Tears were collected and analyzed for interleukin-6 (IL-6), tumor necrosis factor-α (TNF-α), nerve growth factor (NGF) and intercellular adhesion molecule-1 (ICAM-1) levels using multiplex magnetic beads. All measurements were preformed preoperatively and 1 day, 1 week, 1 month and 3 months postoperatively. Results FL scores in ReLEx smile group were lower than those of FS-LASIK group 1 week postoperatively (P = 0.010). Compared to the FS-LASIK group, longer TBUT were observed in ReLEx smile group 1 month (P = 0.029) and 3 months (P = 0.045) postoperatively. No significant differences were found in tear secretion for the two groups (P>0.05). OSDI scores were higher in FS-LASIK group 1 month after surgery (P = 0.020). Higher central corneal sensitivity was observed in ReLEx smile group 1 week, 1 month and 3 months (P<0.05) postoperatively. Compared to FS-LASIK group, lower and faster recovery of IL-6 and NGF levels in tears was observed in ReLEx smile group postoperatively (P<0.05). Tears TNF-α and ICAM-1 concentrations were not significantly different between the two groups at any follow-up time (P>0.05). Moreover, IL-6 and NGF levels correlated with ocular surface changes after ReLEx smile or FS-LASIK. Conclusions In the early postoperative period, ReLEx smile results in milder ocular surface changes than FS-LASIK. Furthermore, the tear inflammatory mediators IL-6 and NGF may play a crucial role

Four-year follow-up of corneal aberrations and visual functions of myopic patients after laser in situ keratomileusis

PubMed Central

Liu, Tai-Xiang; Chen, Yong-Tao; Dan, Ting-Ting; Shi, Rong; Linghu, Shao-Rong; Li, Hai-Xiang

2015-01-01

Objective: To report on 4-year follow-up of corneal higher-order aberrations and daily visual functions of myopic patients after laser in situ keratomileusis (LASIK). Methods: One hundred thirty four eyes of 67 patients who underwent LASIK guided by aspherical ablation were included in this study. The vision, corneal spherical aberration (SphA) and Coma were recorded before LASIK and at 6 month and 4 year after LASIK. The evaluation of the questionnaire about daily visual functions was performed by the same physician after LASIK. Results: No eye decreased the BCVA during 4 year follow-up. The effect index and safety index were 1.08±0.16, 1.11±0.17 and 1.12±0.16, 1.13±0.14 respectively at 6 month and 4 year post-LASIK. After LASIK the corneal SphA and Coma were significantly increased, however the difference between 6 month and 4 year post-LASIK was no statistical significance. Most patients (94.3%-92.4%) felt satisfaction or high satisfaction about the ability to perform each daily visual function after LASIK. Meanwhile there was still about 7.4%-9.2% patients who complained that they could not drive at night. Further analysis showed that the score of driving at night was negative correlation with corneal SphA (r=-0.645, p=0.040; r=-0.688, p=0.040 at 6 month and 4 year post-LASIK respectively). Conclusions: Our four-year follow-up outcomes indicated that the myopic patients after LASIK had the long-term stable corneal aberration and satisfaction of daily visual functions. PMID:26870114

[Post-lasik corneal ectasia in patients with significant differences in keratometry readings between both eyes].

PubMed

Ortega-Usobiaga, J; Llovet-Osuna, F; Djodeyre, M R; Llovet-Rausell, A; Beltran-Sanz, J; Baviera-Sabater, J

2014-03-01

A study is made on the incidence of corneal ectasia after laser in situ keratomileusis (LASIK) in patients with large differences in mean keratometry (MK) readings between both eyes (OU). Visual outcomes were also evaluated. The medical records of 164,603 patients (315,259 eyes) who underwent LASIK from January 2003 to December 2011 were reviewed in order to identify patients with a difference in MK of ≥ 1.25 D between OU. The main outcome measures were incidence of ectasia after LASIK, and visual outcome. A total of 35 eyes that met the inclusion criteria were found. Functional and visual results were those expected for myopia studies. After a minimum follow-up of 2 years, no corneal ectasia was found in 3 eyes (2 patients). The possibility of finding a patient with an asymmetry in MK and normal topography is low (0.021%), and it does not seem to be a contraindication of LASIK. Although no corneal ectasia was found in this case series, and as it is a potentially sight-threatening complication, patients with very different MK between OU should be studied carefully before undergoing LASIK. Copyright © 2013 Sociedad Española de Oftalmología. Published by Elsevier Espana. All rights reserved.

Complications of femtosecond-assisted laser in-situ keratomileusis flaps.

PubMed

Shah, Deepika N; Melki, Samir

2014-01-01

Femtosecond-assisted laser in-situ keratomileusis flaps have revolutionized refractive surgery since their introduction. Although these lasers are exceedingly safe, complications still do occur. This review focuses specifically on examining the literature and evidence for flap complications during femtosecond-assisted laser in-situ keratomileusis as well as their management.

Assessment of the Psychometric Properties of a Questionnaire Assessing Patient-Reported Outcomes With Laser In Situ Keratomileusis (PROWL).

PubMed

Hays, Ron D; Tarver, Michelle E; Spritzer, Karen L; Reise, Steve; Hilmantel, Gene; Hofmeister, Elizabeth M; Hammel, Keri; May, Jeanine; Ferris, Frederick; Eydelman, Malvina

2017-01-01

Patient-reported outcome (PRO) measures for laser in situ keratomileusis (LASIK) are needed. To develop PRO measures to assess satisfaction, eye-related symptoms, and their effect on functioning and well-being following LASIK based on patient and expert input. The Patient-Reported Outcomes With LASIK (PROWL) studies were prospective observational studies of patients undergoing LASIK surgery for myopia, hyperopia, or astigmatism. PROWL-1 was a single-center study of active-duty US Navy personnel and PROWL-2 was a 5-center study of civilians. PROWL-1 enrolled 262 active-duty service personnel and PROWL-2 enrolled 312 civilians 21 years or older who spoke English; 241 individuals in PROWL-1 and 280 in PROWL-2 completed a baseline questionnaire before surgery. The analytic sample included those also completing 1 or more follow-up questionnaires: 240 (99.6%) of those in PROWL-1 and 271 (94.4%) of those in PROWL-2. Questionnaires were self-administered through the internet preoperatively and at 1 and 3 months postoperatively in both studies and at 6 months postoperatively in PROWL-1. PROWL-1 began in August 2011 and was completed May 30, 2014; PROWL-2 began in July 2012 and was completed June 27, 2014. Data were analyzed from June 28, 2014, to October 24, 2016. Scales assessing visual symptoms (double images, glare, halos, and starbursts), dry eye symptoms, satisfaction with vision, and satisfaction with LASIK surgery. Items from the National Eye Institute (NEI) Refractive Error Quality of Life Instrument (NEI-RQL-42), NEI Visual Function Questionnaire (NEI-VFQ), and the Ocular Surface Disease Index (OSDI) were included. All scales are scored on a 0 to 100 possible range. Construct validity and responsiveness to change were evaluated (comparing scores before and after surgery). The median age of the 240-person PROWL-1 analytic sample was 27 years (range, 21-52 years); 49 were women (20.4%). The median age of the 271-person PROWL-2 analytic sample was 30 years (range, 21

[LenSx® femto-LASIK, FEMTO LDV Z4® femto-LASIK, and PRK : Comparison of refractive results and an analysis of complications].

PubMed

Pahlitzsch, T; Pahlitzsch, M-L; Sumarni, U; Pahlitzsch, M

2017-10-30

The aim of this study is to evaluate three refractive procedures: LenSx® (Alcon, Fort Worth, TX, USA) femto-laser in situ keratomileusis (LASIK), FEMTO LDV Z4® (Ziemer, Port, Switzerland) femto-LASIK, and photorefractive keratectomy (PRK) in terms of refractive outcome, perioperative complications, pain, and patient satisfaction. Data of 168 eyes (myopic n = 84) were included in this retrospective study. Of these, 54 eyes (n = 27, 33.85 ± 7.64 years) were treated with LenSx® femto-LASIK, 60 eyes (n = 30, 35.03 ± 7.46 years) with FEMTO LDV Z4® femto-LASIK, and 54 eyes (n = 27, 33.24 ± 8.52 years) with PRK. Photoablation was induced by a MEL80 Excimerlaser (Zeiss, Oberkochen, Germany). The corrected (V sc ) and uncorrected (V cc ) distance subjective visual acuity, corneal topography (Pentacam® HR; Wetzlar, Germany), and objective astigmatism (ARK-760A Refractometer ; Nidek, Fremont, CA, USA) were measured preoperatively, and 1 day, 1 week, 1 month, and 3 months postoperatively. Subjective pain (verbal rating scale) and patient satisfaction were also recorded. Subjective V sc showed significantly better results in both femto-LASIK cohorts compared to PRK (p < 0.05) 1 day and 1 week postoperatively. There was no significant difference between the groups in terms of spherical equivalent and astigmatism 3 months postoperatively. The LenSx® femto-LASIK caused flap complications. The highest patient satisfaction results were shown in the LDV Z4® group, followed by the LenSx® and PRK cohorts (p = 0.072). LDV Z4® femto-LASIK showed the lowest pain score 1 day postoperatively (p < 0.001). There was no significant correlation between target refraction and preoperative corneal thickness and astigmatism. Femtosecond laser-assisted LASIK is an effective procedure enabling rapid rehabilitation of visual acuity with low postoperative pain compared to PRK. There is no difference between the three techniques regarding refractive outcome after 3�

Femtosecond Laser in situ Keratomileusis Flap Creation in Narrow Palpebral Fissure Eyes without Suction

PubMed Central

Chang, John S.M.; Law, Antony K.P.; Ng, Jack C.M.; Cheng, May S.Y.

2017-01-01

Purpose To evaluate a surgical technique used in eyes with narrow palpebral fissure undergoing femtosecond laser flap creation without suction during laser in situ keratomileusis (LASIK). Methods All data of 2 patient groups were collected through chart review. Group 1 consisted of 6 eyes with narrow palpebral fissure in which the suction ring was manually fixated and femtosecond laser was applied accordingly. Thirty comparison cases were randomly drawn from among eyes that underwent a standard LASIK procedure matched for age and preoperative refraction (group 2). Only 1 eye of each patient was selected to compare the refractive and visual outcomes between groups. Results In all group 1 eyes, the flaps were created successfully with manual fixation of the suction ring without suction. No eyes lost 2 or more lines of vision. No significant difference was found in the safety and refractive outcomes between groups. Conclusion Manual fixation of the suction ring in eyes with narrow palpebral fissure without suction was feasible for flap creation during LASIK. PMID:28690535

Evaluation of thermal load during laser corneal refractive surgery using infrared thermography

NASA Astrophysics Data System (ADS)

Brunsmann, U.; Sauer, U.; Arba-Mosquera, S.; Magnago, T.; Triefenbach, N.

2010-09-01

Infrared thermography is used for evaluation of the mean temperature as a measure of thermal load during corneal refractive surgery. An experimental method to determine emissivity and to calibrate the thermografic system is presented. In a case study on the porcine eye two dimensional temperature distributions with lateral resolution of 170 μm and line scans with temporal resolution of 13 μs are discussed with respect to the meaning of mean temperature. Using the newest generation of surgery equipment it is shown, that the mean temperature rise can be kept below 5 °C during myopic laser in situ keratomileusis (LASIK) treatments corresponding to an aberration-free correction of -2.75 diopter.

A Longitudinal Study on the Effects of Laser Refractive Eye Surgery in Military Aircrew

DTIC Science & Technology

2005-02-01

Photorefractive Keratectomy ( PRK ) and Laser in situ keratomileusis ( LASIK ) have been approved for all classes of licenses providing the clinical...photoréfractive ( PRK ) et la kératomileusie in-situ au laser ( LASIK ) ont été approuvées pour toutes les classes de licences à condition que les résultats...had approved PRK and LASIK for all classes of licenses in Civilian Aviation, provided that the clinical outcome was satisfactory and that minimum

Intacs for keratoconus and post-LASIK ectasia: mechanical versus femtosecond laser-assisted channel creation.

PubMed

Carrasquillo, Karen G; Rand, Janet; Talamo, Jonathan H

2007-09-01

To evaluate the efficacy of intracorneal ring segments to treat keratoconus and post-laser in situ keratomileusis (LASIK) keratectasia implanted by using either mechanical dissection or a femtosecond laser. Thirty-three eyes of 29 patients had intracorneal ring segments implanted by using mechanical dissection (17 eyes) or a femtosecond laser (16 eyes). Mean follow-up was 10.3 months. Parameters assessed before and after surgery included uncorrected visual acuity (UCVA), best spectacle-corrected visual acuity (BSCVA), manifest refractive spherical equivalent (MRSE), refractive cylinder (RC), best contact lens-corrected visual acuity (BCLVA), and contact lens tolerance. Statistically significant changes occurred for all parameters when we analyzed all 33 eyes as 1 group. Mean UCVA LogMar values improved from 1.0 +/- 0.3 (20/200) to 0.6 +/- 0.4 (20/80) (P < 0.0005). Mean BSCVA changed from 0.3 +/- 0.2 (20/40) to 0.2 +/- 0.2 (20/30) (10%; P < 0.05), and MRSE from -9 +/- 4 to -7 +/- 4 D (P < 0.05; 20%). There was a decrease of 0.5 D or more of RC in 62% of eyes. BCLVA improved from 0.2 +/- 0.2 (20/30) to 0.1 +/- 0.1 (20/25) after surgery (P < 0.02). Contact lens tolerance improved in 81% of eyes. There was no statistically significant difference in outcomes between mechanical dissection and femtosecond laser-assisted techniques. However, although statistical power was adequate to detect changes in clinical parameters as a result of surgery, it was not sufficient to conclusively show such differences between surgical techniques. For mild to moderate cases of keratoconus and post-LASIK keratectasia, the use of a femtosecond laser for Intacs channel creation seems as effective as mechanical dissection. Future studies are warranted to further evaluate channel creation by a femtosecond laser.

A retrospective comparison of efficacy and safety of 680 consecutive lasik treatments for high myopia performed with two generations of flying-spot excimer lasers.

PubMed

Gazieva, Lola; Beer, Mette Hjuler; Nielsen, Kim; Hjortdal, Jesper

2011-12-01

To compare the visual refractive outcome and complication of laser in situ keratomileusis (LASIK) carried out with a Carl Zeiss-Meditec MEL-70 Excimer laser and a MEL-80 laser for treatment of high myopia. Journal records of 680 consecutive eyes that underwent LASIK with a Schwind Supratome microkeratome and a MEL-70 Excimer laser (Group A), or a Moria M2 microkeratome and a MEL-80 Excimer laser (Group B) were reviewed. Manifest refraction, uncorrected and best spectacle-corrected visual acuity (BSCVA), corneal topography and central corneal thickness (CCT) were recorded before and 3 months after treatment. Pre- and postoperative complications, visual and refractive outcome and frequency of retreatments were registered. Mean preoperative spherical equivalent refraction was -8.52 dioptres (-5.50- -18 dioptres), and the mean attempted laser correction was -8.02 dioptres (-5.50- -11 dioptres). Three months after LASIK, the average treatment error (difference between achieved and attempted correction) was 1.20 (SD=1.19) dioptres of under correction in Group A and 0.52 (SD=1.00) dioptres in Group B. Four eyes lost more than two lines of BSCVA (0.6%). In 110 eyes (16%), a re-LASIK procedure was performed to reduce remaining myopia after the primary procedure. Laser in situ keratomileusis treatment for high myopia can effectively reduce high degrees of myopia. Under correction was observed in both treatment groups but Group B has a slightly better predictability. Significant loss of BSCVA occurs infrequently after LASIK for even considerable grades of myopia (0.6% in each group). © 2010 The Authors. Journal compilation © 2010 Acta Ophthalmol.

Comparison of photorefractive keratectomy and laser in situ keratomileusis for myopia of -6 D or less using the Nidek EC-5000 laser.

PubMed

Fernández, A P; Jaramillo, J; Jaramillo, M

2000-01-01

We compared the efficacy, predictability, and safety of photorefractive keratectomy (PRK) and laser in situ keratomileusis (LASIK) for the surgical correction of low and moderate myopia. A retrospective study was performed to evaluate uncorrected and spectacle-corrected visual acuity, and manifest refraction 1 year after PRK or LASIK. All procedures were done using an automatic microkeratome (Chiron Ophthalmic) and the Nidek EC-5000 excimer laser. PRK was performed in 75 eyes of 45 patients and LASIK in 133 eyes of 77 patients. Mean age for PRK patients was 32.8 years (range, 18 to 52 yr) and LASIK patients was 29.6 years (range, 18 to 49 yr). Mean preoperative spherical equivalent refraction for PRK patients was -3.28 D (range, -1.00 to -6.00 D) and LASIK, -3.86 D (range, -1.00 to -6.00 D). One year after surgery, mean spherical equivalent refraction for Group 1 (baseline, -1.00 to -3.00 D) PRK eyes was -0.18 +/- 0.61 D (range, -1.50 to +0.75 D) and for LASIK eyes, -0.08 +/- 0.61 D (range, -1.50 to +1.62 D), with no statistically significant difference. For Group 2 eyes (baseline, -3.25 to -6.00 D), mean spherical equivalent refraction for PRK eyes was -0.44 +/- 0.87 D (range, -2.00 to +2.12 D) and for LASIK eyes, -0.09 +/- 0.83 D (range, -1.50 to +1.75 D), with no statistically significant difference. The antilogarithm of the mean UCVA (antilogUCVA) in Group 1 for PRK was 0.79 +/- 0.21 (20/25) and for LASIK was 0.87 +/- 0.19 (20/23), with no statistically significant difference. The antilogUCVA in Group 2 for PRK eyes was 0.70 +/- 0.24 (20/28) and for LASIK eyes was 0.83 +/- 0.18 (20/24), with a statistically significant difference (0.7 vs. 0.83, P < .005). The percentage of eyes with a postoperative UCVA >20/40 in Group 1 for PRK was 91.5% (38 eyes) and for LASIK was 95% (50 eyes) (no statistically significant difference), and in Group 2 for PRK eyes, it was 82% (27 eyes) and 97.5% (78 eyes) for LASIK (statistically significant difference, P < .05). PRK and

Incidence of rainbow glare after laser in situ keratomileusis flap creation with a 60 kHz femtosecond laser.

PubMed

Bamba, Sonya; Rocha, Karolinne M; Ramos-Esteban, Jerome C; Krueger, Ronald R

2009-06-01

To report the incidence of and factors associated with rainbow glare after laser in situ keratomileusis (LASIK) flap creation with a 60 kHz femtosecond laser. Department of Refractive Surgery, Cleveland Clinic Cole Eye Institute, Cleveland, Ohio, USA. Consecutive patients having LASIK by the same surgeon were questioned during postoperative examinations or by telephone about postoperative rainbow glare (radiating colors around a white light at night). Femtosecond laser (IntraLase) settings included pulse frequency 60 kHz, flap thickness 90 to 110 mum, and spot/line separation 8 mum. Raster energy was 0.8 microJ (75% of eyes) and 1.0 to 1.1 microJ (25%). Excimer laser ablation was performed with the LADAR 4000 or 6000 platform using custom or conventional treatments. Of 260 consecutive patients, 256 (98.5%) were successfully contacted. Fifteen patients (28 eyes) reported postoperative rainbow glare (5.8%), described as 4 to 12 bands of color around a white light, with 6 bands most common. The symptom did not correlate with refractive error, age, or sex but was more frequent at 1.0 microJ or 1.1 microJ raster energy (11.6%) than at 0.8 microJ (4.1%). The incidence followed a bimodal distribution, with the first grouping due to inadequate alignment and higher energy just after laser installation and the second just before a later maintenance service call. Rainbow glare is a mild optical side effect of femtosecond LASIK. In this study, higher raster energy levels and length of time between service calls were associated with the occurrence of rainbow glare.

Role of percent peripheral tissue ablated on refractive outcomes following hyperopic LASIK

PubMed Central

Stapleton, Fiona; Versace, Patrick

2017-01-01

Objectives To determine the effect of hyperopic laser in situ keratomileusis (H-LASIK) on corneal integrity, by investigating relationships between proportionate corneal tissue ablated and refractive outcomes at 3 months. Methods 18 eyes of 18 subjects treated with H-LASIK by Technolas 217c Excimer Laser were included in the study. Orbscan II Topography System was used to determine corneal volume and pachymetry 3mm temporally (3T). The volume of corneal tissue ablated was determined from the laser nomogram. Univariate associations between age, treatment, corneal volume, overall proportion of tissue removed, proportion of tissue removed at 3T, residual bed thickness at 3T and refractive outcomes 3 months post-LASIK were examined and independent factors associated with refractive outcomes determined using linear regression models. Results At 3 months post-LASIK, the mean difference to expected refractive outcome was -0.20 ± 0.64 (Range -2.00 to +1.00). In univariate analysis, difference to expected refractive outcome was associated with proportion of tissue removed at 3T (P<0.01, r = -0.605) and total number of pulses (P< 0.05, r = -0.574). In multivariable analysis, difference to expected refractive outcome was associated with the proportion of tissue removed at 3T only. Conclusion Subjects undergoing H-LASIK, may present as either over or under-corrected at 3 months. The proportion of tissue removed at 3T was the single significant determinant of this outcome, suggesting unexpected biomechanical alterations resulting in corneal steepening. Future hyperopic LASIK procedures could consider proportionate volume of corneal tissue removed at 3T in addition to laser nomograms to achieve improved refractive outcomes. PMID:28151939

Femtosecond lasers for laser in situ keratomileusis: a systematic review and meta-analysis

PubMed Central

Huhtala, Anne; Pietilä, Juhani; Mäkinen, Petri; Uusitalo, Hannu

2016-01-01

Purpose The aim of this study was to review and meta-analyze whether there are differences between reported femtosecond (FS) lasers for laser-assisted in situ keratomileusis (LASIK) in terms of efficacy, predictability, and safety as primary outcomes and corneal flap thickness measurements and pre- and postoperative complications as secondary outcomes. Methods A comprehensive literature search of PubMed, Science Direct, Scopus, and Cochrane CENTRAL Trials Library databases was conducted to identify the relevant prospective randomized controlled trials of FS lasers for LASIK. Thirty-one articles describing a total of 5,404 eyes were included. Results Based on efficacy, IntraLase FS 10 and 30 kHz gave the best results. Based on predictability and safety, there were no differences between various FS lasers. FEMTO LDV and IntraLase FS 60 kHz produced the most accurate flap thicknesses. IntraLase and Wavelight SF200 had the fewest intraoperative complications. IntraLase, Visumax, and Wavelight FS200 had the most seldom postoperative complications. Conclusion There were dissimilarities between different FS lasers based on efficacy and intraoperative and postoperative complications. All FS lasers were predictable and safe for making corneal flaps in LASIK. PMID:27022236

Femtosecond lasers for laser in situ keratomileusis: a systematic review and meta-analysis.

PubMed

Huhtala, Anne; Pietilä, Juhani; Mäkinen, Petri; Uusitalo, Hannu

2016-01-01

The aim of this study was to review and meta-analyze whether there are differences between reported femtosecond (FS) lasers for laser-assisted in situ keratomileusis (LASIK) in terms of efficacy, predictability, and safety as primary outcomes and corneal flap thickness measurements and pre- and postoperative complications as secondary outcomes. A comprehensive literature search of PubMed, Science Direct, Scopus, and Cochrane CENTRAL Trials Library databases was conducted to identify the relevant prospective randomized controlled trials of FS lasers for LASIK. Thirty-one articles describing a total of 5,404 eyes were included. Based on efficacy, IntraLase FS 10 and 30 kHz gave the best results. Based on predictability and safety, there were no differences between various FS lasers. FEMTO LDV and IntraLase FS 60 kHz produced the most accurate flap thicknesses. IntraLase and Wavelight SF200 had the fewest intraoperative complications. IntraLase, Visumax, and Wavelight FS200 had the most seldom postoperative complications. There were dissimilarities between different FS lasers based on efficacy and intraoperative and postoperative complications. All FS lasers were predictable and safe for making corneal flaps in LASIK.

Management of long-standing partially torn and flipped laser in situ keratomileusis flaps.

PubMed

Kim, Jin Sun; Chung, Byunghoon; Lee, Taekjune; Kim, Woon Cho; Kim, Tae-im; Kim, Eung Kweon

2015-02-01

We describe 2 cases of traumatized and torn laser in situ keratomileusis (LASIK) flaps, partially flipped anteriorly or posteriorly, fixed for 8 months or 4 months, and accompanied by epithelial ingrowth. The 2 patients had had uneventful bilateral LASIK 6 years and 1 year before the trauma. In Case 1, the anteriorly flipped flap was removed with transepithelial phototherapeutic keratectomy. Next, mitomycin-C 0.04% was applied for 30 seconds. In Case 2, the portion of the flap that was flipped posteriorly and buried under the remaining intact LASIK flap was restored to its original normal position and epithelial ingrowth was removed mechanically with a microcurette. Irrigation with 20% ethanol was performed to inhibit the recurrence of interfacial epithelial ingrowth. The stretched amniotic membrane overlay over the cornea and sclera was sutured tightly to the episclera as the biologic pressure patch for the inhibition of epithelial re-ingrowth. Good visual acuity was restored in both cases. No author has a financial or proprietary interest in any material or method mentioned. Copyright © 2015 ASCRS and ESCRS. Published by Elsevier Inc. All rights reserved.

Comparison of real and computer-simulated outcomes of LASIK refractive surgery

NASA Astrophysics Data System (ADS)

Cano, Daniel; Barbero, Sergio; Marcos, Susana

2004-06-01

Computer simulations of alternative LASIK ablation patterns were performed for corneal elevation maps of 13 real myopic corneas (range of myopia, -2.0 to -11.5 D). The computationally simulated ablation patterns were designed with biconic surfaces (standard Munnerlyn pattern, parabolic pattern, and biconic pattern) or with aberrometry measurements (customized pattern). Simulated results were compared with real postoperative outcomes. Standard LASIK refractive surgery for myopia increased corneal asphericity and spherical aberration. Computations with the theoretical Munnerlyn ablation pattern did not increase the corneal asphericity and spherical aberration. The theoretical parabolic pattern induced a slight increase of asphericity and spherical aberration, explaining only 40% of the clinically found increase. The theoretical biconic pattern controlled corneal spherical aberration. Computations showed that the theoretical customized pattern can correct high-order asymmetric aberrations. Simulations of changes in efficiency due to reflection and nonnormal incidence of the laser light showed a further increase in corneal asphericity. Consideration of these effects with a parabolic pattern accounts for 70% of the clinical increase in asphericity.

Corneal collagen cross-linking in the stabilization of PRK, LASIK, thermal keratoplasty, and orthokeratology.

PubMed

Nguyen, Michelle K; Chuck, Roy S

2013-07-01

To describe the use of corneal collagen cross-linking (CXL) and its efficacy in the stabilization of keratorefractive procedures, including PRK, laser in-situ keratomileusis (LASIK), thermal keratoplasty, and orthokeratology. Since its introduction, CXL has quickly gained interest in the treatment of ectactic disorders due to its ability to increase the biomechanical stability of the cornea. In its earliest use, it has shown to be effective in the treatment of both keratoconus and post-LASIK ectasia. More recent studies of CXL in combination with keratorefractive procedures have shown varying degrees of success. CXL with PRK has shown to be effective in slowing or halting the progression of keratoconus, pellucid marginal degeneration, and post-LASIK ectasia, in addition to potentially decreasing or delaying the need for penetrating keratoplasty. Several small case series have also demonstrated improved stability and efficacy of PRK and LASIK when combined with CXL, as well as a potentially decreased risk of postprocedure ectasia. In conjunction with thermokeratoplasty and orthokeratology, CXL has shown improved but only temporary results in the treatment of keratoconus. Future studies are needed to determine the efficacy and long-term stability of CXL in combination with keratorefractive procedures, as well as to address possible complications.

Mechanisms of Optical Regression Following Corneal Laser Refractive Surgery: Epithelial and Stromal Responses

PubMed Central

MOSHIRFAR, Majid; DESAUTELS, Jordan D.; WALKER, Brian D.; MURRI, Michael S.; BIRDSONG, Orry C.; HOOPES, Phillip C. Sr

2018-01-01

Laser vision correction is a safe and effective method of reducing spectacle dependence. Photorefractive Keratectomy (PRK), Laser In Situ Keratomileusis (LASIK), and Small-Incision Lenticule Extraction (SMILE) can accurately correct myopia, hyperopia, and astigmatism. Although these procedures are nearing optimization in terms of their ability to produce a desired refractive target, the long term cellular responses of the cornea to these procedures can cause patients to regress from the their ideal postoperative refraction. In many cases, refractive regression requires follow up enhancement surgeries, presenting additional risks to patients. Although some risk factors underlying refractive regression have been identified, the exact mechanisms have not been elucidated. It is clear that cellular proliferation events are important mediators of optical regression. This review focused specifically on cellular changes to the corneal epithelium and stroma, which may influence postoperative visual regression following LASIK, PRK, and SMILE procedures. PMID:29644238

Dry Eye after Small Incision Lenticule Extraction (SMILE) versus Femtosecond Laser-Assisted in Situ Keratomileusis (FS-LASIK) for Myopia: A Meta-Analysis.

PubMed

Shen, Zeren; Zhu, Yanan; Song, Xiaohui; Yan, Jie; Yao, Ke

2016-01-01

To compare dry eye after small incision lenticule extraction (SMILE) and femtosecond laser-assisted LASIK (FS-LASIK) for correcting myopia. CENTRAL, Embase and PubMed were searched in November 2016. All randomized controlled trials (RCTs) and prospective cohorts that compared dry eye after SMILE with FS-LASIK were selected. Five cohorts and one RCT were identified for comparing dry eye after SMILE (291 eyes) and FS-LASIK (277 eyes). The pooled results revealed that the SMILE and FS-LASIK groups did not differ significantly in terms of Schirmer's I test (SIT) and tear film osmolarity (TFO) at any postoperative visits. By contrast, tear break up time (TBUT; p = 0.04 for one month, p < 0.001 for three months, and p = 0.02 for six months) and ocular surface disease index (OSDI; p < 0.001 for one month and three months, and p = 0.006 for six months) were significantly worse in the FS-LASIK group than in the SMILE group at follow-up. At six months postoperatively, TBUT and TFO values in both the SMILE and FS-LASIK groups and OSDI scores in the SMILE group returned to preoperative levels, but SIT values in both groups (p = 0.02 for the SMILE group and p < 0.001 for the FS-LASIK group) and OSDI in the FS-LASIK group (p < 0.001) were still statistically impaired. Dry eye after both SMILE and FS-LASIK usually occurs transiently. SMILE does not show obvious superiority over FS-LASIK by exhibiting similar and acceptable objective parameters, and SMILE may have milder subjective symptoms.

Effects of Altitude Exposure in Photorefractive Keratectomy (PRK) Subjects

DTIC Science & Technology

2006-08-01

changes in RK and early post-op Laser In-situ Keratomileusis ( LASIK ) subjects but not in PRK subjects. The Tanzer8 study evaluated 30 naval aviators...Pikes Peak. The Pikes Peak study, conducted over a three days at 14,100 feet, reported no significant change in PRK and LASIK treated subjects as...The effect of hypoxia on refraction following LASIK surgery. IOVS 1999; 40(4):S895 4. Ng JD, White LJ, Parmley VC, Hubickey W, Carter J, Mader TH

Femtosecond Laser Flap Creation for Laser In Situ Keratomileusis in the Setting of Previous Radial Keratotomy.

PubMed

Rush, Sloan W; Rush, Ryan B

2015-01-01

The aim of the study was to report the outcomes of laser in situ keratomileusis (LASIK) in subjects with previous radial keratotomy (RK) using a novel femtosecond laser setting on a proprietary femtosecond laser platform. This was a retrospective, consecutive chart review of patients at a single private practice institution. The medical records of 16 eyes of 8 subjects who underwent femtosecond-assisted LASIK for consecutive hyperopia after RK were retrospectively reviewed. The preoperative characteristics, intraoperative details, and postoperative outcomes were analyzed. All 16 eyes had successful femtosecond laser flap creation without significant intraoperative or postoperative complications. Uncorrected visual acuity significantly improved postoperatively (P = 0.0142) and remained stable through the final follow-up interval at 9 to 12 months postoperatively. None of the subjects lost any lines of best spectacle-corrected visual acuity in the postoperative period. The novel femtosecond laser technique described in this study can provide a safe and effective method for patients undergoing LASIK after previous RK. Future investigations are required to further validate the findings reported in this study.

Diffuse lamellar keratitis after laser in situ keratomileusis with the Moria LSK-One and Carriazo-Barraquer microkeratomes.

PubMed

Thammano, Pavika; Rana, Azhar N; Talamo, Jonathan H

2003-10-01

To assess risk factors for and incidence of diffuse lamellar keratitis (DLK) and to investigate whether microkeratome design is associated with the incidence of DLK. The Laser Eye Consultants of Boston, Boston and Waltham, Massachusetts, USA. In a retrospective nonrandomized comparative study, 1122 consecutive primary laser in situ keratomileusis (LASIK) treatments (584 patients) were analyzed to determine the incidence of DLK using 2 different microkeratome designs (Moria LSK-One [LSK] and Moria Carriazo-Barraquer [C-B]). The incidence of DLK was as determined by clinical signs. The overall incidence of DLK was 2.23%. The incidence in the LSK and C-B groups was 1.09% and 4.38%, respectively, with a statistically significant difference in incidence between the 2 groups (P<.01). Epithelial irregularities increased the risk for DLK. There was no significant statistical difference in sex, age, operating room location, type of laser, or time of day the surgery was performed between the 2 groups or between eyes that had DLK and eyes without DLK. The incidence of DLK using the C-B microkeratome fell significantly after May 2000, when new cleaning methods for this device were introduced. Different microkeratomes and how they are maintained may influence the incidence of DLK. Diffuse lamellar keratitis is more common after LASIK in a setting of epithelial irregularities, whether or not an actual epithelial defect is created.

Examination of tear film smoothness on corneae after refractive surgeries using a noninvasive interferometric method

NASA Astrophysics Data System (ADS)

Szczesna, Dorota H.; Kulas, Zbigniew; Kasprzak, Henryk T.; Stenevi, Ulf

2009-11-01

A lateral shearing interferometer was used to examine the smoothness of the tear film. The information about the distribution and stability of the precorneal tear film is carried out by the wavefront reflected from the surface of tears and coded in interference fringes. Smooth and regular fringes indicate a smooth tear film surface. On corneae after laser in situ keratomileusis (LASIK) or radial keratotomy (RK) surgery, the interference fringes are seldom regular. The fringes are bent on bright lines, which are interpreted as tear film breakups. The high-intensity pattern seems to appear in similar location on the corneal surface after refractive surgery. Our purpose was to extract information about the pattern existing under the interference fringes and calculate its shape reproducibility over time and following eye blinks. A low-pass filter was applied and correlation coefficient was calculated to compare a selected fragment of the template image to each of the following frames in the recorded sequence. High values of the correlation coefficient suggest that irregularities of the corneal epithelium might influence tear film instability and that tear film breakup may be associated with local irregularities of the corneal topography created after the LASIK and RK surgeries.

Twelve-Year Follow-Up of Laser In Situ Keratomileusis for Moderate to High Myopia.

PubMed

Ikeda, Tetsuya; Shimizu, Kimiya; Igarashi, Akihito; Kasahara, Sumie; Kamiya, Kazutaka

2017-01-01

To assess the long-term clinical outcomes of conventional laser in situ keratomileusis (LASIK) for moderate to high myopia. We retrospectively examined sixty-eight eyes of 37 consecutive patients who underwent conventional LASIK for the correction of myopia (-3.00 to -12.75 diopters (D)). At 3 months and 1, 4, 8, and 12 years postoperatively, we assessed the safety, efficacy, predictability, stability, mean keratometry, central corneal thickness, and adverse events. The safety and efficacy indices were 0.82 ± 0.29 and 0.67 ± 0.37, respectively, 12 years postoperatively. At 12 years, 53% and 75% of the eyes were within 0.5 and 1.0 D, respectively, of the targeted correction. Manifest refraction changes of -0.74 ± 0.99 D occurred from 3 months to 12 years after LASIK ( p < 0.001). We found a significant correlation of refractive regression with the changes in keratometric readings from 3 months to 12 years postoperatively (Pearson correlation coefficient, r = -0.28, p = 0.02), but not with the changes in central corneal thickness ( r = -0.08, p = 0.63). No vision-threatening complications occurred in any case. Conventional LASIK offered good safety outcomes during the 12-year observation period. However, the efficacy and the predictability gradually decreased with time owing to myopic regression in relation to corneal steepening.

Optical Coherence Tomography Accurately Measures Corneal Power Change From Laser Refractive Surgery

PubMed Central

McNabb, Ryan P.; Farsiu, Sina; Stinnett, Sandra S.; Izatt, Joseph A.; Kuo, Anthony N.

2014-01-01

Purpose To determine the ability of motion corrected optical coherence tomography (OCT) to measure the corneal refractive power change due to laser in situ keratomileusis (LASIK). Design Evaluation of a diagnostic test or technology in a cohort. Subjects 70 eyes from 37 subjects undergoing LASIK were measured preoperatively. 39 eyes from 22 subjects were measured postoperatively and completed the study. Methods Consecutive patients undergoing LASIK at the Duke Eye Center who consented to participate were imaged with Placido-ring topography, Scheimpflug photography and OCT on the day of their surgery. Patients were then reimaged with the same imaging systems at the post-operative month 3 visit. Change in pre- to post-operative corneal refractive power as measured by each of the imaging modalities was compared to the pre- to post-operative change in manifest refraction using t-test with generalized estimating equations. Main Outcome Measures Corneal refractive power change due to LASIK as measured by Placido-ring topography, Scheimpflug Photography, and OCT compared to the manifest refraction change vertexed to the corneal plane. The change in manifest refraction should correspond to the change in the corneal refractive power from LASIK and was considered the reference measurement. Results In 22 returning post-LASIK individuals (39 eyes), we found no significant difference between the clinically measured pre to post LASIK change in manifest refraction and both Scheimpflug photography (p = 0.714) and OCT (p = 0.216). In contrast, keratometry values from Placido-ring topography were found to be significantly different from the measured refractive change (p < 0.001). Additionally, of the three imaging modalities, OCT recorded the smallest mean absolute difference from the reference measurement with the least amount of variability. Conclusion Motion corrected OCT more accurately measures the change in corneal refractive power due to laser refractive surgery than

Dry Eye after Small Incision Lenticule Extraction (SMILE) versus Femtosecond Laser-Assisted in Situ Keratomileusis (FS-LASIK) for Myopia: A Meta-Analysis

PubMed Central

Shen, Zeren; Zhu, Yanan; Song, Xiaohui; Yan, Jie; Yao, Ke

2016-01-01

Purpose To compare dry eye after small incision lenticule extraction (SMILE) and femtosecond laser-assisted LASIK (FS-LASIK) for correcting myopia. Methods CENTRAL, Embase and PubMed were searched in November 2016. All randomized controlled trials (RCTs) and prospective cohorts that compared dry eye after SMILE with FS-LASIK were selected. Results Five cohorts and one RCT were identified for comparing dry eye after SMILE (291 eyes) and FS-LASIK (277 eyes). The pooled results revealed that the SMILE and FS-LASIK groups did not differ significantly in terms of Schirmer’s I test (SIT) and tear film osmolarity (TFO) at any postoperative visits. By contrast, tear break up time (TBUT; p = 0.04 for one month, p < 0.001 for three months, and p = 0.02 for six months) and ocular surface disease index (OSDI; p < 0.001 for one month and three months, and p = 0.006 for six months) were significantly worse in the FS-LASIK group than in the SMILE group at follow-up. At six months postoperatively, TBUT and TFO values in both the SMILE and FS-LASIK groups and OSDI scores in the SMILE group returned to preoperative levels, but SIT values in both groups (p = 0.02 for the SMILE group and p < 0.001 for the FS-LASIK group) and OSDI in the FS-LASIK group (p < 0.001) were still statistically impaired. Conclusion Dry eye after both SMILE and FS-LASIK usually occurs transiently. SMILE does not show obvious superiority over FS-LASIK by exhibiting similar and acceptable objective parameters, and SMILE may have milder subjective symptoms. PMID:27992482

Three-year changes in epithelial and stromal thickness after PRK or LASIK for high myopia.

PubMed

Ivarsen, Anders; Fledelius, Walther; Hjortdal, Jesper Ø

2009-05-01

To compare 3-year changes in corneal sublayer thickness after photorefractive keratectomy (PRK) or laser in situ keratomileusis (LASIK). Forty-six patients with spheroequivalent refraction of -6.0 to -8.0 diopters (D) were randomly assigned to PRK or LASIK. One eye from each patient was included in the study. Examinations included manifest refraction and confocal microscopy through focusing (CMTF) and were performed preoperatively and postoperatively at 1 week and at 1, 3, 6, 12, and 36 months. From CMTF scans, the thicknesses of the central cornea (CT), epithelium (ET), stroma (ST), LASIK flap (FT), and residual stromal bed (BT) were calculated. After LASIK, spheroequivalent refraction averaged -0.76 D by 1 week and -1.19 D by 1 month, with no subsequent significant change. ET increased 9.0 +/- 7.0 microm within 1 week and remained constant thereafter. ST increased 12.9 +/- 9.4 microm within 1 year because of increased BT. One week after PRK, refraction averaged -0.23 D and stabilized at -1.42 D by 6 months. By 1 week, ET was reduced by 7.5 +/- 5.7 microm, reached preoperative thickness by 6 months, and increased further 7.3 +/- 6.0 microm by 3 years. ST increased 25.3 +/- 17.2 microm during 1 year, correlating with the postoperative refractive regression. After both procedures, changes in CT also correlated with refractive changes. No other correlations were identified. PRK and LASIK induce a persistent increase in ET that stabilizes 1 week after LASIK and 1 year after PRK. Stromal regrowth is most pronounced after PRK. After LASIK, regrowth is restricted to the residual stromal bed. Postoperative refractive changes correlate with changes in ST (PRK) and CT (PRK and LASIK) but not with changes in ET.

Functional Outcome and Patient Satisfaction after Laser In Situ Keratomileusis for Correction of Myopia and Myopic Astigmatism

PubMed Central

Bamashmus, Mahfouth A.; Hubaish, Khammash; Alawad, Mohammed; Alakhlee, Hisham

2015-01-01

Purpose: The purpose was to evaluate subjective quality of vision and patient satisfaction after laser in situ keratomileusis (LASIK) for myopia and myopic astigmatism. Patients and Methods: A self-administered patient questionnaire consisting 29 items was prospectively administered to LASIK patients at the Yemen Magrabi Hospital. Seven scales covering specific aspects of the quality of vision were formulated including; global satisfaction; quality of uncorrected and corrected vision; quality of night vision; glare; daytime driving and; night driving. Main outcome measures were responses to individual questions and scale scores and correlations with clinical parameters. The scoring scale ranged from 1 (dissatisfied) to 3 (very satisfied) and was stratified in the following manner: 1-1.65 = dissatisfied; 1.66-2.33 = satisfied and; 2.33-3 = very satisfied. Data at 6 months postoperatively are reported. Results: This study sample was comprised of 200 patients (122 females: 78 males) ranging in age from 18 to 46 years old. The preoperative myopic sphere was − 3.50 ± 1.70 D and myopic astigmatism was 0.90 ± 0.82 D. There were 96% of eyes within ± 1.00 D of the targeted correction. Postoperatively, the uncorrected visual acuity was 20/40 or better in 99% of eyes. The mean score for the overall satisfaction was 2.64 ± 0.8. A total of 98.5% of patients was satisfied or very satisfied with their surgery, 98.5% considered their main goal for surgery was achieved. Satisfaction with uncorrected vision was 2.5 ± 0.50. The main score for glare was 1.98 ± 0.7 at night. Night driving was rated more difficult preoperatively by 6.2%, whereas 79% had less difficulty driving at night. Conclusion: Patient satisfaction with uncorrected vision after LASIK for myopia and myopic astigmatism appears to be excellent and is related to the residual refractive error postoperatively. PMID:25624684

New developments in corneal and external disease--LASIK.

PubMed

Dhaliwal, Deepinder K; Mather, Rookaya

2003-03-01

Lamellar refractive surgery has evolved into LASIK, which is a widely performed, versatile procedure with a high patient acceptance. In this chapter, the two main components of LASIK were discussed: flap creation and stromal ablation. In each of these areas, the authors explored current technology and new advances, including the femtosecond laser and wavefront-guided ablations. Expanded indications and therapeutic application of LASIK also have come to the forefront. The treatment of anisomyopic amblyopia in the pediatric population is a prime example and was discussed fully in this chapter. The field of refractive surgery has never been stagnant. Surgeons and scientists continue to explore new modalities to increase safety, to improve results, and to broaden applications that benefit the patient population.

Comparison of efficacy and safety of laser in situ keratomileusis using 2 femtosecond laser platforms in contralateral eyes.

PubMed

Rosman, Mohamad; Hall, Reece C; Chan, Cordelia; Ang, Andy; Koh, Jane; Htoon, Hla Myint; Tan, Donald T H; Mehta, Jodhbir S

2013-07-01

To compare the efficacy, predictability, and refractive outcomes of laser in situ keratomileusis (LASIK) using 2 femtosecond platforms for flap creation. Multisurgeon single center. Clinical trial. Bilateral femtosecond LASIK was performed using the Wavelight Allegretto Eye-Q 400 Hz excimer laser system. The Visumax femtosecond platform (Group 1) was used to create the LASIK flap in 1 eye, while the Intralase femtosecond platform (Group 2) was used to create the LASIK flap in the contralateral eye. The preoperative, 1-month, and 3-month postoperative visual acuities, refraction, and contrast sensitivity in the 2 groups were compared. The study enrolled 45 patients. Three months after femtosecond LASIK, 79.5% of eyes in Group 1 and 82.1% in Group 2 achieved an uncorrected distance visual acuity of 20/20 (P=.808). The mean efficacy index was 0.97 in Group 1 and 0.98 in Group 2 at 3 months (P=.735); 89.7% of eyes in Group 1 and 84.6% of eyes in Group 2 were within ± 0.50 diopter of emmetropia at 3 months (P=.498). No eye in either group lost more than 2 lines of corrected distance visual acuity. The mean safety index at 3 months was 1.11 in Group 1 and 1.10 in Group 2 (P=.570). The results of LASIK with both femtosecond lasers were similar, and both platforms produced efficacious and predictable LASIK outcomes. No author has a financial or proprietary interest in any material or method mentioned. Copyright © 2013 ASCRS and ESCRS. Published by Elsevier Inc. All rights reserved.

Safety and efficacy of wavefront-guided myopic laser in situ keratomileusis using a new wavefront sensor technology: first 100 cases.

PubMed

Smadja, David; Santhiago, Marcony R; Tellouck, Joy; De Castro, Tania; Lecomte, Fanny; Mello, Glauco R; Touboul, David

2015-08-01

To evaluate the safety and efficacy of wavefront-guided laser in situ keratomileusis (LASIK) for the correction of low to high myopia and myopic astigmatism using data derived from a new-generation Hartmann-Shack aberrometer. Refractive Surgery Unit, Bordeaux Hospital University, France. Retrospective case series. This retrospective study analyzed the initial group of eyes treated with wavefront-guided LASIK for myopia and myopic astigmatism using the Visx S4IR excimer laser and wavefront data derived from a new Hartmann-Shack aberrometer (iDesign Advanced Wavescan aberrometer). Refractive (refraction and refractive accuracy) and visual outcomes (uncorrected [UDVA] and corrected [CDVA] distance visual acuities) were recorded 3 months postoperatively. The study included 100 eyes of 50 consecutively treated patients. The mean decimal UDVA improved from 0.1 ± 0.1 (SD) preoperatively to 1.1 ± 0.15 postoperatively (P < .01). A monocular UDVA of 20/16, 20/20, and 20/25 were achieved in 76.6%, 94.4%, and 96.6% of eyes, respectively. The postoperative manifest spherical equivalent was within ±0.5 diopter in all eyes. No eye lost 2 or more lines of CDVA, and 29.2% of the eyes gained 1 or more lines of CDVA. Wavefront-guided LASIK performed using data derived from the new Hartmann-Shack aberrometer was safe, effective, and predictable for treating myopia and myopic astigmatism. No author has a financial or proprietary interest in any material or method mentioned. Copyright © 2015 ASCRS and ESCRS. Published by Elsevier Inc. All rights reserved.

A prospective comparison of phakic collamer lenses and wavefront-optimized laser-assisted in situ keratomileusis for correction of myopia

PubMed Central

Parkhurst, Gregory D

2016-01-01

Purpose The aim of this study was to evaluate and compare night vision and low-luminance contrast sensitivity (CS) in patients undergoing implantation of phakic collamer lenses or wavefront-optimized laser-assisted in situ keratomileusis (LASIK). Patients and methods This is a nonrandomized, prospective study, in which 48 military personnel were recruited. Rabin Super Vision Test was used to compare the visual acuity and CS of Visian implantable collamer lens (ICL) and LASIK groups under normal and low light conditions, using a filter for simulated vision through night vision goggles. Results Preoperative mean spherical equivalent was −6.10 D in the ICL group and −6.04 D in the LASIK group (P=0.863). Three months postoperatively, super vision acuity (SVa), super vision acuity with (low-luminance) goggles (SVaG), super vision contrast (SVc), and super vision contrast with (low luminance) goggles (SVcG) significantly improved in the ICL and LASIK groups (P<0.001). Mean improvement in SVaG at 3 months postoperatively was statistically significantly greater in the ICL group than in the LASIK group (mean change [logarithm of the minimum angle of resolution, LogMAR]: ICL =−0.134, LASIK =−0.085; P=0.032). Mean improvements in SVc and SVcG were also statistically significantly greater in the ICL group than in the LASIK group (SVc mean change [logarithm of the CS, LogCS]: ICL =0.356, LASIK =0.209; P=0.018 and SVcG mean change [LogCS]: ICL =0.390, LASIK =0.259; P=0.024). Mean improvement in SVa at 3 months was comparable in both groups (P=0.154). Conclusion Simulated night vision improved with both ICL implantation and wavefront-optimized LASIK, but improvements were significantly greater with ICLs. These differences may be important in a military setting and may also affect satisfaction with civilian vision correction. PMID:27418804

A prospective comparison of phakic collamer lenses and wavefront-optimized laser-assisted in situ keratomileusis for correction of myopia.

PubMed

Parkhurst, Gregory D

2016-01-01

The aim of this study was to evaluate and compare night vision and low-luminance contrast sensitivity (CS) in patients undergoing implantation of phakic collamer lenses or wavefront-optimized laser-assisted in situ keratomileusis (LASIK). This is a nonrandomized, prospective study, in which 48 military personnel were recruited. Rabin Super Vision Test was used to compare the visual acuity and CS of Visian implantable collamer lens (ICL) and LASIK groups under normal and low light conditions, using a filter for simulated vision through night vision goggles. Preoperative mean spherical equivalent was -6.10 D in the ICL group and -6.04 D in the LASIK group (P=0.863). Three months postoperatively, super vision acuity (SVa), super vision acuity with (low-luminance) goggles (SVaG), super vision contrast (SVc), and super vision contrast with (low luminance) goggles (SVcG) significantly improved in the ICL and LASIK groups (P<0.001). Mean improvement in SVaG at 3 months postoperatively was statistically significantly greater in the ICL group than in the LASIK group (mean change [logarithm of the minimum angle of resolution, LogMAR]: ICL =-0.134, LASIK =-0.085; P=0.032). Mean improvements in SVc and SVcG were also statistically significantly greater in the ICL group than in the LASIK group (SVc mean change [logarithm of the CS, LogCS]: ICL =0.356, LASIK =0.209; P=0.018 and SVcG mean change [LogCS]: ICL =0.390, LASIK =0.259; P=0.024). Mean improvement in SVa at 3 months was comparable in both groups (P=0.154). Simulated night vision improved with both ICL implantation and wavefront-optimized LASIK, but improvements were significantly greater with ICLs. These differences may be important in a military setting and may also affect satisfaction with civilian vision correction.

Z-LASIK and Trans-PRK for correction of high-grade myopia: safety, efficacy, predictability and clinical outcomes.

PubMed

Gershoni, Assaf; Mimouni, Michael; Livny, Eitan; Bahar, Irit

2018-03-12

The aim of the study was to examine the outcomes of transepithelial photorefractive keratectomy (Trans-PRK) and Femtosecond Laser-assisted in situ keratomileusis (Z-LASIK) for the correction of high myopia. A retrospective cohort study design was used. The study group included 792 eyes with high-grade myopia (- 6.0 diopters or higher) or high-grade myopia with astigmatism that were treated with Z-LASIK or Trans-PRK in 2013 through 2014 in an optical outpatient clinic of a large private medical service. The Trans-PRK group comprised of 674 eyes with a spherical equivalent (SE) of - 7.87 ± 1.46 and the Z-LASIK group comprised of 118 eyes with a SE of - 7.19 ± 0.81 (P < 0.001). The mean postoperative SE in the Trans-PRK group was - 0.06 and - 0.02 in the Z-LASIK group (P = 0.545). Efficacy index values were 0.92 in the Trans-PRK group and 0.95 in the Z-LASIK group (P = 0.083), and corresponding safety index values were 0.95 and 0.97 (P = 0.056). An UCVA of 20/40 or better was achieved in 94.20% of eyes in the Trans-PRK group, and 98.31% in the Z-LASIK group (P = 0.063). The majority of eyes in both the Trans-PRK and Z-LASIK groups were within ± 0.5D of attempted correction: 59.35 and 64.71%, respectively (P = 0.271). Both Trans-PRK and Z-LASIK demonstrated excellent efficacy, safety and predictability profiles, with results comparable and in some cases superior to the current literature. Results of Z-LASIK were slightly better than those of Trans-PRK, though the preoperative SE of the latter was higher.

Effect of diquafosol tetrasodium eye drop for persistent dry eye after laser in situ keratomileusis.

PubMed

Mori, Yosai; Nejima, Ryohei; Masuda, Ayami; Maruyama, Yoko; Minami, Keiichiro; Miyata, Kazunori; Amano, Shiro

2014-07-01

To evaluate the effect of diquafosol tetrasodium (DQS) for the treatment of persistent dry eye after laser in situ keratomileusis (LASIK). Miyata Eye Hospital, Miyazaki, Japan. Noncomparative case series. This prospective study included 30 eyes of 15 patients in whom dry eye had persisted for over 12 months after LASIK, and the symptoms had not improved with artificial tears and sodium hyaluronate treatment. In addition, treatment with DQS 3% eye drops, 6 times a day, was performed for 12 weeks. Best-corrected visual acuity, tear secretion with the Schirmer test, tear break-up time, and fluorescein and lissamine green staining scores on the cornea and conjunctiva were examined before and at 1, 4, and 12 weeks after the addition. A subjective questionnaire of 14 symptoms was also assessed before and 12 weeks after treatment. The fluorescein and lissamine green staining scores significantly improved over 12 weeks; however, the best-corrected visual acuity and tear secretion did not change. The symptoms of fatigue, dryness, grittiness, discomfort, difficulty in reading, and discomfort within the area of dryness improved after the additional DQS treatment. The DQS treatment improved the subjective and objective symptoms of persistent dry eye after LASIK. Increased mucin production because of the addition of DQS probably improved the tear film stability and reduced the symptoms of dry eye in patients who had persistent dry eye after LASIK.

LASIK versus photorefractive keratectomy for high myopic (> 3 diopter) astigmatism.

PubMed

Katz, Toam; Wagenfeld, Lars; Galambos, Peter; Darrelmann, Benedikt Große; Richard, Gisbert; Linke, Stephan Johannes

2013-12-01

To compare the efficacy, safety, predictability, and vector analysis indices of LASIK and photorefractive keratectomy (PRK) for correction of high cylinder of greater than 3 diopters (D) in myopic eyes. The efficacy, safety, and predictability of LASIK or PRK performed in 114 consecutive randomly selected myopic eyes with an astigmatism of greater than 3 D were retrospectively analyzed at the 2- to 6-month follow-up visits. Vector analysis of the cylindrical correction was compared between the treatment groups. A total of 57 eyes receiving PRK and 57 eyes receiving LASIK of 114 refractive surgery candidates were enrolled in the study. No statistically significant difference in efficacy [efficacy index = 0.76 (±0.32) for PRK vs 0.74 (±0.19) for LASIK (P = .82)], safety [safety index = 1.10 (±0.26) for PRK vs 1.01 (±0.17) for LASIK (P = .121)], or predictability [achieved astigmatism < 1 D in 39% of PRK- and 54% of LASIK-treated eyes, and < 2 D in 88% of PRK- and 89% of LASIK-treated eyes (P = .218)] was demonstrated. Using Alpins vector analysis, the surgically induced astigmatism and difference vector were not significantly different between the surgery methods, whereas the correction index showed a slight and significant advantage of LASIK over PRK (1.25 for PRK and 1.06 for LASIK, P < .001). LASIK and PRK are comparably safe, effective, and predictable procedures for excimer laser correction of high astigmatism of greater than 3 D in myopic eyes. Predictability of the correction of the cylindrical component is lower than that of the spherical equivalent. Copyright 2013, SLACK Incorporated.

The Changes of Tear Status after Conventional and Wavefront-Guided IntraLASIK

PubMed Central

Foo, Say Kiang; Kaur, Sharanjeet; Abd Manan, Faudziah; Low, Aloysius Joseph

2011-01-01

Background: IntraLASIK is a LASIK surgery that involved IntraLase femtosecond laser for the corneal flap creating. The objective of this research was to investigate and compare the changes in tear status at 1 and 3 months after undergoing conventional IntraLASIK with Bausch & Lomb PlanoScan (PS) algorithm, Bausch & Lomb Zyoptix Tissue Saving (ZTS) algorithm, and wavefront-guided (WG) IntraLASIK with VISX CustomVue. Methods: Tear status of 36 patients who were divided into 3 groups depending on the type of IntraLASIK they underwent (PS, n = 13; ZTS, n = 9; WG, n = 14) was evaluated. Tear status was determined by classifying the category of the thickness of pre-corneal tear lipid layer, non-invasive tear break-up time, and tear meniscus height. Repeated measures analysis of variance (ANOVA) and one way ANOVA were used for the statistical analyses. Results: The category of the thickness of tear lipid layer, non-invasive tear break up time and tear meniscus height were neither significantly changed after IntraLASIK for all groups nor showed significant difference among groups at 1 and 3 months post-IntraLASIK (P > 0.05). Blinking rate and palpebral aperture also had no significant changed after IntraLASIK. Conclusion: Both conventional (PS and ZTS) and WG IntraLASIK did not affect tear status up to 3 months post-IntraLASIK. WG IntraLASIK did not show superiority in preserving tear status 1 and 3 months post-surgery compared with conventional IntraLASIK. PMID:22135584

Twelve-Year Follow-Up of Laser In Situ Keratomileusis for Moderate to High Myopia

PubMed Central

Ikeda, Tetsuya; Igarashi, Akihito; Kasahara, Sumie

2017-01-01

Purpose To assess the long-term clinical outcomes of conventional laser in situ keratomileusis (LASIK) for moderate to high myopia. Methods We retrospectively examined sixty-eight eyes of 37 consecutive patients who underwent conventional LASIK for the correction of myopia (−3.00 to −12.75 diopters (D)). At 3 months and 1, 4, 8, and 12 years postoperatively, we assessed the safety, efficacy, predictability, stability, mean keratometry, central corneal thickness, and adverse events. Results The safety and efficacy indices were 0.82 ± 0.29 and 0.67 ± 0.37, respectively, 12 years postoperatively. At 12 years, 53% and 75% of the eyes were within 0.5 and 1.0 D, respectively, of the targeted correction. Manifest refraction changes of −0.74 ± 0.99 D occurred from 3 months to 12 years after LASIK (p < 0.001). We found a significant correlation of refractive regression with the changes in keratometric readings from 3 months to 12 years postoperatively (Pearson correlation coefficient, r = −0.28, p = 0.02), but not with the changes in central corneal thickness (r = −0.08, p = 0.63). No vision-threatening complications occurred in any case. Conclusions Conventional LASIK offered good safety outcomes during the 12-year observation period. However, the efficacy and the predictability gradually decreased with time owing to myopic regression in relation to corneal steepening. PMID:28596969

Multiple regression analysis in nomogram development for myopic wavefront laser in situ keratomileusis: Improving astigmatic outcomes.

PubMed

Allan, Bruce D; Hassan, Hala; Ieong, Alvin

2015-05-01

To describe and evaluate a new multiple regression-derived nomogram for myopic wavefront laser in situ keratomileusis (LASIK). Moorfields Eye Hospital, London, United Kingdom. Prospective comparative case series. Multiple regression modeling was used to derive a simplified formula for adjusting attempted spherical correction in myopic LASIK. An adaptation of Thibos' power vector method was then applied to derive adjustments to attempted cylindrical correction in eyes with 1.0 diopter (D) or more of preoperative cylinder. These elements were combined in a new nomogram (nomogram II). The 3-month refractive results for myopic wavefront LASIK (spherical equivalent ≤11.0 D; cylinder ≤4.5 D) were compared between 299 consecutive eyes treated using the earlier nomogram (nomogram I) in 2009 and 2010 and 414 eyes treated using nomogram II in 2011 and 2012. There was no significant difference in treatment accuracy (variance in the postoperative manifest refraction spherical equivalent error) between nomogram I and nomogram II (P = .73, Bartlett test). Fewer patients treated with nomogram II had more than 0.5 D of residual postoperative astigmatism (P = .0001, Fisher exact test). There was no significant coupling between adjustments to the attempted cylinder and the achieved sphere (P = .18, t test). Discarding marginal influences from a multiple regression-derived nomogram for myopic wavefront LASIK had no clinically significant effect on treatment accuracy. Thibos' power vector method can be used to guide adjustments to the treatment cylinder alongside nomograms designed to optimize postoperative spherical equivalent results in myopic LASIK. mentioned. Copyright © 2015 ASCRS and ESCRS. Published by Elsevier Inc. All rights reserved.

Modeling the influence of LASIK surgery on optical properties of the human eye

NASA Astrophysics Data System (ADS)

Szul-Pietrzak, Elżbieta; Hachoł, Andrzej; Cieślak, Krzysztof; Drożdż, Ryszard; Podbielska, Halina

2011-11-01

The aim was to model the influence of LASIK surgery on the optical parameters of the human eye and to ascertain which factors besides the central corneal radius of curvature and central thickness play the major role in postsurgical refractive change. Ten patients were included in the study. Pre- and postsurgical measurements included standard refraction, anterior corneal curvature and pachymetry. The optical model used in the analysis was based on the Le Grand and El Hage schematic eye, modified by the measured individual parameters of corneal geometry. A substantial difference between eye refractive error measured after LASIK and estimated from the eye model was observed. In three patients, full correction of the refractive error was achieved. However, analysis of the visual quality in terms of spot diagrams and optical transfer functions of the eye optical system revealed some differences in these measurements. This suggests that other factors besides corneal geometry may play a major role in postsurgical refraction. In this paper we investigated whether the biomechanical properties of the eyeball and changes in intraocular pressure could account for the observed discrepancies.

[Analysis of corneal biomechanical changes after femtosecond laser-assisted laser in situ keratomileusis in children with hyperopic anisometropia].

PubMed

Kulikova, I L; Shlenskaya, O V; Chapurin, N V

to analyze corneal hysteresis (CH) and corneal resistance factor (RF) readings obtained with the Reichert Ocular Response Analyzer (ORA) before and after hyperopic femtolaser-assisted laser in situ keratomileusis (FS-LASIK) in children with anisometropia as well as to establish factors that may cause changes in these parameters. CH and RF were evaluated before and 1.5 years after FS-LASIK performed on amblyopic eyes of 28 patients aged 6-14 years. Preoperatively, there was a correlation between CH and RF (r=0.41, p=0.03). No correlation was found between CH and age (r=-0.02, p=0.82) or between CH (r=0.00, p=0.98), RF (r=0.04, p=0.83), and cornea thickness. The mean preoperative CH was 12.56±1.21 mmHg, RF 12.31±1.57 mmHg. Postoperatively, a statistically significant change occurred to both CH (by 0.97±1.51 mmHg, p=0.002) and RF (by 1.42±1.55 mmHg, p=0.000). No correlation was found between CH before and after surgery (r=0.11, p=0.57) as well as between the ablation depth and changes in CH (r=0,04, p=0.83) and RF (r=0.21, p=0.28). Regression analysis showed that the extent of CH (r2=0.52, p=0.00) and RF (r2=0,48, p=0.00) changes was closely related to their preoperative values. The statistically significant relative change in CH and RF after hyperopic FS-LASIK was 8% and 12%, respectively. CH and RF changes correlated with their preoperative values, but not with the ablation depth or cornea thickness.

Comparison of Higher Order Aberrations after Wavefront-guided LASIK and PRK: One Year Follow-Up Results.

PubMed

Jahadi Hosseini, Seyed Hamid Reza; Abtahi, Seyed Mohammad Bagher; Khalili, Mohammad Reza

2016-01-01

To evaluate the changes and predictability of higher order aberrations (HOAs) after personalized laser in situ keratomileusis (LASIK) and personalized photorefractive keratectomy (PRK) for simple myopia and compound myopic astigmatism. In this prospective cross-sectional study, 100 eyes were included. A total of 50 eyes underwent personalized LASIK and 50 eyes underwent personalized PRK. Preoperative and postoperative wavefront data were compared between the two groups. The influential factors and predictability of HOAs were also assessed. Total HOA increased in the amount of 0.01 ± 0.14 μm for the 5 mm pupil ( P = 0.55) and 0.08 ± 0.22 μm for the 6 mm pupil ( P = 0.02) after PRK; however after LASIK the corresponding values for the 5 and 6 mm pupil sizes were 0.05 ± 0.12 and 0.15 ± 0.18 μm, respectively ( P < 0. 001). Mean changes were not significantly different between the PRK and LASIK groups for both 5 and 6 mm pupil sizes ( P = 0.21 and P = 0.13, respectively). Spherical aberration increased following LASIK more than following PRK ( P < 0.001). Changes in the root mean square (RMS) of total HOA had a statistically significant negative correlation ( P < 0.001) with its preoperative value. HOA and spherical aberration reduced in majority of eyes when the preoperative spherical equivalent refraction was low. For the 6mm pupil size, the total HOA increased following both personalized PRK and LASIK with no significant difference between the two groups. Change of the total HOA RMS was influenced by the preoperative values. The known influencing factors could predict nearly 50% of the changes in total HOA.

Dry eyes and corneal sensation after laser in situ keratomileusis with femtosecond laser flap creation Effect of hinge position, hinge angle, and flap thickness.

PubMed

Mian, Shahzad I; Li, Amy Y; Dutta, Satavisha; Musch, David C; Shtein, Roni M

2009-12-01

To determine whether corneal sensation and dry-eye signs and symptoms after myopic laser in situ keratomileusis (LASIK) surgery with a femtosecond laser are affected by varying hinge position, hinge angle, or flap thickness. University-based academic practice, Ann Arbor, Michigan, USA. This prospective randomized contralateral-eye study evaluated eyes after bilateral myopic LASIK with a femtosecond laser (IntraLase). Superior and temporal hinge positions, 45-degree and 90-degree hinge angles, and 100 microm and 130 microm corneal flap thicknesses were compared. Postoperative follow-up at 1 week and 1, 3, 6, and 12 months included central Cochet-Bonnet esthesiometry, the Ocular Surface Disease Index questionnaire, a Schirmer test with anesthesia, tear breakup time (TBUT), corneal fluorescein staining, and conjunctival lissamine green staining. The study evaluated 190 consecutive eyes (95 patients). Corneal sensation was reduced at all postoperative visits, with improvement over 12 months (P<.001). There was no difference in corneal sensation between the different hinge positions, angles, or flap thicknesses at any time point. The overall ocular surface disease index score was increased at 1 week, 1 month, and 3 months (P<.0001, P<.0001, and P = .046, respectively). The percentage of patients with a TBUT longer than 10 seconds was significantly lower at 1 week and 1 month (P<.0001). Dry-eye syndrome after myopic LASIK with a femtosecond laser was mild and improved after 3 months. Corneal flap hinge position, hinge angle, and thickness had no effect on corneal sensation or dry-eye syndrome.

Femtosecond-assisted laser in situ keratomileusis for consecutive hyperopia after radial keratotomy.

PubMed

Leccisotti, Antonio; Fields, Stefania V

2015-08-01

To evaluate femtosecond-assisted laser in situ keratomileusis (LASIK) for the treatment of hyperopic shift after radial keratotomy (RK). Private practice, Siena, Italy. Prospective case series. Eyes with a spherical equivalent (SE) of +1.0 diopters (D) to +4.0 D after RK with 6 or 8 incisions had LASIK. The flap (nominal thickness 130 μm) was created with a femtosecond laser (LDV Z2); the refractive ablation was performed with an excimer laser (217P). The flap was dissected in a centrifugal fashion along previous RK cuts. Eighteen eyes of 10 patients were treated. Preoperatively, the mean defocus equivalent was 3.13 diopters (D) ± 0.71 (SD); the corrected distance visual acuity (CDVA) was 0.09 ± 0.06 logMAR. At 9 months, the mean defocus equivalent was 0.51 ± 0.47 D (P < .05), with 13 eyes (72%) having 0.50 D or less of defocus equivalent and 16 eyes (89%) having 1.0 D or less of defocus equivalent. The mean CDVA was 0.04 ± 0.06 logMAR (P < .05). No lines of logMAR CDVA were lost. The mean uncorrected distance visual acuity was 0.11 ± 0.10 logMAR. The safety index was 1.11; the efficacy index was 0.97. No retreatments were performed. Flap complications were limited to an RK incision opening larger than 2 mm in 3 eyes and 1 case of a small, self-limiting epithelial ingrowth. Laser in situ keratomileusis with a low-energy femtosecond laser was a safe and effective approach to treat post-RK hyperopia, causing no relevant inflammation. Neither author has a financial or proprietary interest in any material or method mentioned. Copyright © 2015 ASCRS and ESCRS. Published by Elsevier Inc. All rights reserved.

Effect of Myopic Defocus on Visual Acuity after Phakic Intraocular Lens Implantation and Wavefront-guided Laser in Situ Keratomileusis

PubMed Central

Kamiya, Kazutaka; Shimizu, Kimiya; Igarashi, Akihito; Kawamorita, Takushi

2015-01-01

This study aimed to investigate the effect of myopic defocus on visual acuity after phakic intraocular lens (IOL) implantation and wavefront-guided laser in situ keratomileusis (wfg-LASIK). Our prospective study comprised thirty eyes undergoing posterior chamber phakic IOL implantation and 30 eyes undergoing wfg-LASIK. We randomly measured visual acuity under myopic defocus after cycloplegic and non-cycloplegic correction. We also calculated the modulation transfer function by optical simulation and estimated visual acuity from Campbell & Green’s retinal threshold curve. Visual acuity in the phakic IOL group was significantly better than that in the wfg-LASIK group at myopic defocus levels of 0, –1, and –2 D (p < 0.001, p < 0.001, and p = 0.02, Mann-Whitney U-test), but not at a defocus of –3 D (p = 0.30). Similar results were also obtained in a cycloplegic condition. Decimal visual acuity values at a myopic defocus of 0, −1, −2, and -3 D by optical simulation were estimated to be 1.95, 1.21, 0.97, and 0.75 in the phakic IOL group, and 1.39, 1.11, 0.94, and 0.71 in the wfg-LASIK group, respectively. From clinical and optical viewpoints, phakic IOL implantation was superior to wfg-LASIK in terms of the postoperative visual performance, even in the presence of low to moderate myopic regression. PMID:25994984

Combined application of prophylactic corneal cross-linking and laser in-situ keratomileusis - a review of literature.

PubMed

Chan, Tommy C Y; Ng, Alex L K; Chan, Karen K W; Cheng, George P M; Wong, Ian Y H; Jhanji, Vishal

2017-11-01

Laser in-situ keratomileusis (LASIK) is safe and effective laser refractive procedures in treating refractive errors. However, regression of treatment and iatrogenic keratectasia remain to be a major concern, especially in treating thin cornea with high ametropia. Collagen cross-linking (CXL) is an effective method in stopping keratoconus progression through increasing the biomechanical strength of the cornea. Adjuvant cross-linking to refractive procedures can theoretically help prevent regression and reduce the risk of keratectasia development by increasing the mechanical stability of cornea. During the procedure, riboflavin is directly applied to the corneal stroma, thereby reducing the need of de-epithelialization as in the conventional protocol for keratoconus. Currently, there is still no consensus regarding the indication of CXL during refractive procedure, nor any standardized treatment protocol. This article aims to summarize the current evidence regarding the use of adjuvant CXL in LASIK. © 2016 Acta Ophthalmologica Scandinavica Foundation. Published by John Wiley & Sons Ltd.

Incidence of corneal infections after laser in situ keratomileusis and surface ablation when moxifloxacin and tobramycin are used as postoperative treatment.

PubMed

Ortega-Usobiaga, Julio; Llovet-Osuna, Fernando; Djodeyre, Mohammad Reza; Llovet-Rausell, Andrea; Beltran, Jaime; Baviera, Julio

2015-06-01

To assess the incidence, culture results, and visual outcomes of infectious keratitis after laser in situ keratomileusis (LASIK) and surface ablation when topical moxifloxacin was added to postoperative prophylaxis with tobramycin. Clínica Baviera, Instituto Oftalmológico Europeo, Bilbao, Spain. Retrospective case series review. The medical records of 55 255 patients (108 014 eyes) who had LASIK and surface ablation were reviewed to identify cases of infectious keratitis. The incidence, risk factors, clinical course, days to diagnosis, treatment, and final visual outcomes were recorded. These data were compared with previously published data of 221 437 eyes that received postoperative tobramycin alone. Post-LASIK infectious keratitis was diagnosed in 10 eyes (9 patients) and post-surface ablation infectious keratitis in 11 eyes (10 patients). The onset of infection was early in 40.00% of cases after LASIK and in 36.36% after surface ablation. Cultures were positive in 2 cases after surface ablation. Immediate flap lifting and irrigation with antibiotics were performed in all eyes after LASIK. The final corrected distance visual acuity was 20/20 or better in 7 cases after LASIK (70.00%) and 7 cases after surface ablation (63.64%) and 20/40 or better in all cases after LASIK or surface ablation. The incidence of infectious keratitis decreased from 0.025% to 0.011% (P < .001) per procedure after LASIK and from 0.200% to 0.066% (P < .001) after surface ablation. Infectious keratitis was less frequent after LASIK than after surface ablation. The frequency of infection, mainly early-onset infection, was lower when the postoperative treatment was tobramycin and moxifloxacin rather than tobramycin alone. No author has a financial or proprietary interest in any material or method mentioned. Copyright © 2015 ASCRS and ESCRS. Published by Elsevier Inc. All rights reserved.

Alternative Refractive Surgery Procedures

MedlinePlus

... alternative refractive surgery procedures to LASIK . Wavefront-Guided LASIK Before surgery, the excimer laser is programmed with ... precise "sculpting" of each unique cornea. In conventional LASIK , this programming is based on the patient's vision ...

Kappa angles in different positions in patients with myopia during LASIK

PubMed Central

Qi, Hui; Jiang, Jing-Jing; Jiang, Yan-Ming; Wang, Li-Qiang; Huang, Yi-Fei

2016-01-01

AIM To investigate the difference in kappa angle between sitting and supine positions during laser-assisted in situ keratomileusis (LASIK). METHODS A retrospective study was performed on 395 eyes from 215 patients with myopia that received LASIK. Low, moderate, and high myopia groups were assigned according to diopters. The horizontal and vertical components of kappa angle in sitting position were measured before the operation, and in supine position during the operation. The data from the two positions were compared and the relationship between kappa angle and diopters were analyzed. RESULTS Two hundred and twenty-three eyes (56.5%) in sitting position and 343 eyes (86.8%) in supine position had positive kappa angles. There were no significant differences in horizontal and vertical components of kappa angle in the sitting position or horizontal components of kappa angle in the supine position between the three groups (P>0.05). A significant difference in the vertical components of kappa angle in the supine position was seen in the three groups (P<0.01). Differences in both horizontal and vertical components of kappa angles were significant between the sitting and supine positions. Positive correlations in both horizontal and vertical components of kappa angles (P<0.05) were found and vertical components of kappa angle in sitting and supine positions were negatively correlated with the degree of myopia (sitting position: r=-0.109; supine position: r=-0.172; P<0.05). CONCLUSION There is a correlation in horizontal and vertical components of kappa angle in sitting and supine positions. Positive correlations in both horizontal and vertical components of kappa angle in sitting and supine positions till the end of the results. This result still needs further observation. Clinicians should take into account different postures when excimer laser surgery needs to be performed. PMID:27162734

Screening for previous refractive surgery in eye bank corneas by using optical coherence tomography.

PubMed

Lin, Roger C; Li, Yan; Tang, Maolong; McLain, Marcy; Rollins, Andrew M; Izatt, Joseph A; Huang, David

2007-06-01

To use optical coherence tomography (OCT) to detect previous refractive surgery in donor corneas. We constructed a tabletop OCT scanner operating at 1310-nm wavelength. Donor corneas at the Cleveland Eye Bank were scanned while sealed within the sterile container immersed in Optisol GS. OCT scanning was performed with 7.6-mm-long lines (512 axial scans) along 8 meridians. Anterior and posterior corneal surfaces were automatically mapped using image processing software that we developed. Curvature was computed from the best parabolic fit in the central 5-mm diameter. Layered analysis of the stromal reflectivity was also performed. Twenty-nine corneas from 19 donors were examined. Five had a history of laser in situ keratomileusis (LASIK). The flap interfaces could not be visualized on slit-lamp or OCT images but were confirmed by histology. The death-to-scan time was 22.1 +/- 11.4 (SD) hours for normal corneas and 100.6 +/- 57.5 hours for LASIK corneas. The anterior surface power was 67.5 +/- 2.5 D in control corneas and 64.5 +/- 2.4 D in LASIK corneas (P = 0.023). There was no significance between the 2 groups in terms of posterior curvature and thickness parameters. The anterior/posterior reflectivity ratio in the central 4-mm diameter was significantly lower in post-LASIK corneas than in control (P < 0.05). OCT provides thickness, topography, and reflectivity maps of donor corneas without taking them out of preservation medium and container. The anterior curvature and the anterior/posterior stromal reflectivity ratio may be useful for detecting previous LASIK.

Using InterWave Aberrometry to Measure and Improve the Quality of Vision in LASIK Surgery

PubMed Central

Thompson, Keith P.; Staver, P. Randall; Garcia, Jose R.; Burns, Stephen A.; Webb, Robert H.; Stulting, R. Doyle

2005-01-01

Objective To compare visual outcomes in eyes undergoing aberrometry-guided (InterWave) LASIK with those in eyes undergoing standard LASIK treatment based upon refractive measures. Design Single-center, comparative, interventional, consecutive case series. Participants Four hundred two consecutive eyes undergoing LASIK were analyzed retrospectively. One group, 106 eyes undergoing primary LASIK and 224 eyes undergoing LASIK enhancement, was treated with standard LASIK treatment using a 5.5-mm optical zone, 1.5-mm transition zone laser with the settings determined by manifest refraction. The second group, 44 untreated (primary) eyes and 28 previously treated (enhancement) eyes, received a multipass, multistage treatment in which the laser settings for each stage were determined by aberrometry measurements. Eyes with desired monovision (undercorrected) outcome and preoperative hyperopia were excluded from the study. Intervention An aberrometry-guided laser treatment (InterWave LASIK) was compared with the standard LASIK treatment based upon the manifest refraction. Main Outcome Measures Uncorrected visual acuity (VA), manifest refraction, best spectacle-corrected VA (BSCVA), severity of halos, and root mean square (RMS) retinal blur area measured at 3 months postoperatively. Results Three months postoperatively there was no difference in uncorrected VA, BSCVA, refraction, or RMS retinal blur areas for pupil sizes of 3.5 mm between eyes treated by InterWave and those treated by standard LASIK. However, InterWave LASIK reduced the retinal blur area by 48% (P<0.0103) and 58% (P<0.0004) in primary cases and 43% (P<0.0430) and 74% (P<0.0271) in enhancement cases, respectively, for pupil sizes of 4.5 and 6.5 mm relative to standard LASIK treatments. Patients undergoing InterWave-guided treatment reported less severity of halo (0.37 vs. 0.98 [P<0.016] for primary cases and 0.35 vs. 0.73 [P<0.04] for enhancement cases). Conclusion InterWave LASIK achieved acuity and refractive

Comparison of Higher Order Aberrations after Wavefront-guided LASIK and PRK: One Year Follow-Up Results

PubMed Central

Jahadi Hosseini, Seyed Hamid Reza; Abtahi, Seyed Mohammad Bagher; Khalili, Mohammad Reza

2016-01-01

Purpose: To evaluate the changes and predictability of higher order aberrations (HOAs) after personalized laser in situ keratomileusis (LASIK) and personalized photorefractive keratectomy (PRK) for simple myopia and compound myopic astigmatism. Methods: In this prospective cross-sectional study, 100 eyes were included. A total of 50 eyes underwent personalized LASIK and 50 eyes underwent personalized PRK. Preoperative and postoperative wavefront data were compared between the two groups. The influential factors and predictability of HOAs were also assessed. Result: Total HOA increased in the amount of 0.01 ± 0.14 μm for the 5 mm pupil (P = 0.55) and 0.08 ± 0.22 μm for the 6 mm pupil (P = 0.02) after PRK; however after LASIK the corresponding values for the 5 and 6 mm pupil sizes were 0.05 ± 0.12 and 0.15 ± 0.18 μm, respectively (P < 0. 001). Mean changes were not significantly different between the PRK and LASIK groups for both 5 and 6 mm pupil sizes (P = 0.21 and P = 0.13, respectively). Spherical aberration increased following LASIK more than following PRK (P < 0.001). Changes in the root mean square (RMS) of total HOA had a statistically significant negative correlation (P < 0.001) with its preoperative value. HOA and spherical aberration reduced in majority of eyes when the preoperative spherical equivalent refraction was low. Conclusion: For the 6mm pupil size, the total HOA increased following both personalized PRK and LASIK with no significant difference between the two groups. Change of the total HOA RMS was influenced by the preoperative values. The known influencing factors could predict nearly 50% of the changes in total HOA. PMID:27994802

Astigmatism induced by conventional spherical ablation after PRK and LASIK in myopia with astigmatism < 1.00 D.

PubMed

Christiansen, Steven M; Mifflin, Mark D; Edmonds, Jason N; Simpson, Rachel G; Moshirfar, Majid

2012-01-01

The purpose of this study was to evaluate surgically-induced astigmatism after spherical ablation in photorefractive keratectomy (PRK) and laser-assisted in situ keratomileusis (LASIK) for myopia with astigmatism < 1.00 D. The charts of patients undergoing spherical PRK or LASIK for the correction of myopia with minimal astigmatism of <1.00 D from 2002 to 2012 at the John A Moran Eye Center in Salt Lake City, UT, were retrospectively reviewed. Astigmatism was measured by manifest refraction. The final astigmatic refractive outcome at 6 months postoperatively was compared with the initial refraction by Alpins vector analysis. For PRK, average cylinder increased from 0.39 ± 0.25 (0.00-0.75) preoperatively to 0.55 ± 0.48 (0.00-1.75) postoperatively (P = 0.014), compared with an increase in LASIK eyes from 0.40 ± 0.27 (0.00-0.75) preoperatively to 0.52 ± 0.45 (0.00-2.00) postoperatively (P = 0.041). PRK eyes experienced an absolute value change in cylinder of 0.41 ± 0.32 (0.00-1.50) and LASIK eyes experienced a change of 0.41 ± 0.31 (0.00-1.50, P = 0.955). Mean surgically-induced astigmatism was 0.59 ± 0.35 (0.00-1.70) in PRK eyes, with an increase in surgically-induced astigmatism of 0.44 D for each additional 1.00 D of preoperative cylinder; in LASIK eyes, mean surgically-induced astigmatism was 0.55 ± 0.32 (0.00-1.80, P = 0.482), with an increase in surgically-induced astigmatism of 0.29 D for each 1.00 D of preoperative cylinder. Spherical ablation can induce substantial astigmatism even in eyes with less than one diopter of preoperative astigmatism in both PRK and LASIK. No significant difference in the magnitude of surgically-induced astigmatism was found between eyes treated with PRK and LASIK, although surgically-induced astigmatism was found to increase with greater levels of preoperative astigmatism in both PRK and LASIK.

Correction factor for ablation algorithms used in corneal refractive surgery with gaussian-profile beams

NASA Astrophysics Data System (ADS)

Jimenez, Jose Ramón; González Anera, Rosario; Jiménez del Barco, Luis; Hita, Enrique; Pérez-Ocón, Francisco

2005-01-01

We provide a correction factor to be added in ablation algorithms when a Gaussian beam is used in photorefractive laser surgery. This factor, which quantifies the effect of pulse overlapping, depends on beam radius and spot size. We also deduce the expected post-surgical corneal radius and asphericity when considering this factor. Data on 141 eyes operated on LASIK (laser in situ keratomileusis) with a Gaussian profile show that the discrepancy between experimental and expected data on corneal power is significantly lower when using the correction factor. For an effective improvement of post-surgical visual quality, this factor should be applied in ablation algorithms that do not consider the effects of pulse overlapping with a Gaussian beam.

Management of epithelial ingrowth after laser in situ keratomileusis on a tertiary care cornea service.

PubMed

Rapuano, Christopher J

2010-03-01

To review the management of epithelial ingrowth after laser in situ keratomileusis (LASIK) on the Wills Eye Institute Cornea Service from 1996 through 2007. Data of all patients referred to the Wills Eye Cornea Service after having undergone LASIK were reviewed. Charts of all patients with the diagnosis of epithelial ingrowth were analyzed. Data included patient demographics, previous ocular history, visual acuity, size and location of the ingrowth, and management. Additional data on eyes that underwent removal of the ingrowth at Wills were obtained. Three hundred five patients (153 female and 152 male, mean age: 44.7 years) were referred for eye problems after LASIK during the study period. Epithelial ingrowth was confirmed in 46 patients (15%) (19 female and 27 male, mean age: 47.4 years) involving 55 eyes (27 right and 28 left). Patients with epithelial ingrowth were seen at a mean of 26 months after LASIK (range: 0.5-108 months). Twenty-four eyes had undergone previous enhancements, 2 twice. Fourteen eyes had undergone previous removal of epithelial ingrowth, 8 more than once (range: 2-8). In 35 eyes, simple observation was recommended. In 7 eyes, epithelial removal was recommended to the referring physician. Thirteen eyes underwent flap lift and epithelial removal at Wills Eye; 9 included flap suturing. One eye required repeat treatment with flap suturing and fibrin glue, after which no recurrence was found. In the other 12 eyes, there was no recurrence in 9, small recurrences in 2, and a large recurrence in 1 eye (mean follow-up: 16 months). Epithelial ingrowth after LASIK is not rare in our referral practice. Mild ingrowth can be observed, whereas significant ingrowth can respond well to removal with a low chance of significant recurrence.

Vector analysis of high (≥3 diopters) astigmatism correction using small-incision lenticule extraction and laser in situ keratomileusis.

PubMed

Chan, Tommy C Y; Wang, Yan; Ng, Alex L K; Zhang, Jiamei; Yu, Marco C Y; Jhanji, Vishal; Cheng, George P M

2018-06-13

To compare the astigmatic correction in high myopic astigmatism between small-incision lenticule extraction and laser in situ keratomileusis (LASIK) using vector analysis. Hong Kong Laser Eye Center, Hong Kong. Retrospective case series. Patients who had correction of myopic astigmatism of 3.0 diopters (D) or more and had either small-incision lenticule extraction or femtosecond laser-assisted LASIK were included. Only the left eye was included for analysis. Visual and refractive results were presented and compared between groups. The study comprised 105 patients (40 eyes in the small-incision lenticule extraction group and 65 eyes in the femtosecond laser-assisted LASIK group.) The mean preoperative manifest cylinder was -3.42 D ± 0.55 (SD) in the small-incision lenticule extraction group and -3.47 ± 0.49 D in the LASIK group (P = .655). At 3 months, there was no significant between-group difference in uncorrected distance visual acuity (P = .915) and manifest spherical equivalent (P = .145). Ninety percent and 95.4% of eyes were within ± 0.5 D of the attempted cylindrical correction for the small-incision lenticule extraction and LASIK group, respectively (P = .423). Vector analysis showed comparable target-induced astigmatism (P = .709), surgically induced astigmatism vector (P = .449), difference vector (P = .335), and magnitude of error (P = .413) between groups. The absolute angle of error was 1.88 ± 2.25 degrees in the small-incision lenticule extraction group and 1.37 ± 1.58 degrees in the LASIK group (P = .217). Small-incision lenticule extraction offered astigmatic correction comparable to LASIK in eyes with high myopic astigmatism. Copyright © 2018 ASCRS and ESCRS. Published by Elsevier Inc. All rights reserved.

Femtosecond Lasers in Ophthalmology: Surgery and Imaging

NASA Astrophysics Data System (ADS)

Bille, J. F.

Ophthalmology has traditionally been the field with prevalent laser applications in medicine. The human eye is one of the most accessible human organs and its transparency for visible and near-infrared light allows optical techniques for diagnosis and treatment of almost any ocular structure. Laser vision correction (LVC) was introduced in the late 1980s. Today, the procedural ease, success rate, and lack of disturbing side-effects in laser assisted in-situ keratomileusis (LASIK) have made it the most frequently performed refractive surgical procedure (keratomileusis(greek): cornea-flap-cutting). Recently, it has been demonstrated that specific aspects of LVC can take advantage of unique light-matter interaction processes that occur with femtosecond laser pulses.

Comparison of Moderate- to High-Astigmatism Corrections Using WaveFront-Guided Laser In Situ Keratomileusis and Small-Incision Lenticule Extraction.

PubMed

Zhang, Jiamei; Wang, Yan; Chen, Xiaoqin

2016-04-01

To evaluate and compare refractive outcomes of moderate- and high-astigmatism correction after wavefront-guided laser in situ keratomileusis (LASIK) and small-incision lenticule extraction (SMILE). This comparative study enrolled a total of 64 eyes that had undergone SMILE (42 eyes) and wavefront-guided LASIK (22 eyes). Preoperative cylindrical diopters were ≤-2.25 D in moderate- and >-2.25 D in high-astigmatism subgroups. The refractive results were analyzed based on the Alpins vector method that included target-induced astigmatism, surgically induced astigmatism, difference vector, correction index, index of success, magnitude of error, angle of error, and flattening index. All subjects completed the 3-month follow-up. No significant differences were found in the target-induced astigmatism, surgically induced astigmatism, and difference vector between SMILE and wavefront-guided LASIK. However, the average angle of error value was -1.00 ± 3.16 after wavefront-guided LASIK and 1.22 ± 3.85 after SMILE with statistical significance (P < 0.05). The absolute angle of error value was statistically correlated with difference vector and index of success after both procedures. In the moderate-astigmatism group, correction index was 1.04 ± 0.15 after wavefront-guided LASIK and 0.88 ± 0.15 after SMILE (P < 0.05). However, in the high-astigmatism group, correction index was 0.87 ± 0.13 after wavefront-guided LASIK and 0.88 ± 0.12 after SMILE (P = 0.889). Both procedures showed preferable outcomes in the correction of moderate and high astigmatism. However, high astigmatism was undercorrected after both procedures. Axial error of astigmatic correction may be one of the potential factors for the undercorrection.

Sources of the monochromatic aberrations induced in human eyes after laser refractive surgery

NASA Astrophysics Data System (ADS)

Porter, Jason

Laser in-situ keratomileusis (LASIK) procedures correct the eye's defocus and astigmatism but also introduce higher order monochromatic aberrations. Little is known about the origins of these induced aberrations. The advent of wavefront sensor technology has made it possible to measure accurately and quickly the aberrations of normal and postoperative LASIK eyes. The goal of this thesis was to exploit this technology to better understand some of the potential mechanisms by which aberrations could be introduced during LASIK. A first step towards investigating these sources was to characterize the aberration changes in post-LASIK eyes. Higher order rms wavefront error increased after conventional and customized LASIK surgery. On average, spherical aberration approximately doubled, and significant changes in vertical and horizontal coma were observed. We examined two sources of postoperative aberrations: the creation of a microkeratome flap and the subsequent laser ablation. Higher order rms increased slightly and there was a wide variation in the response of individual Zernike modes after cutting a flap. The majority of induced spherical aberration was due to the laser ablation and not the flap-cut. Aberrations are also induced by static and dynamic decentrations of the patient's pupil. We found that ablations were typically decentered in the superotemporal direction due to shifts in pupil center location between aberration measurement (dilated) and surgical (undilated) conditions in customized LASIK eyes. There was a weak correlation between the horizontal coma theoretically induced by this offset and that measured postoperatively. Finally, dynamic eye movements during the procedure induce higher order aberrations. We found that the most problematic decentrations during LASIK are relatively slow drifts in eye position. An eye-tracking system with a 2-Hz closed-loop bandwidth could compensate for most eye movements during LASIK. One solution for reducing the

Can Opposite Clear Corneal Incisions Have a Role with Post-laser In Situ Keratomileusis Astigmatism?

PubMed Central

El-Awady, Hatem; Ghanem, Asaad A.

2012-01-01

Purpose: To evaluate the astigmatic correcting effect of paired opposite clear corneal incisions (OCCIs) on the steep axis in patients with residual astigmatism after laser in situ keratomileusis (LASIK) Materials and Methods: Thirty-one eyes of 24 patients with a mean age of 28.4 years ±2.46 (range, 19-36 years) were recruited for the study. Inclusion criteria included residual astigmatism of ≥1.5 diopter (D) after LASIK with inadequate residual stromal bed thickness that precluded ablation. The cohort was divided into two groups; group I (with astigmatism ranging from -1.5 D to -2.5 D) and group II (with astigmatism > -2.5 D). The steep axis was marked prior to surgery. Paired three-step self-sealing opposite clear corneal incisions were performed 1-mm anterior to the limbus on the steep axis with 3.2-mm keratome for group I and 4.1 mm for group II. Patients were examined 1 day, 1 week, 1 month, 3 months and 6 months, postoperatively. Visual acuity, refraction, keratometry, and corneal topography were evaluated preoperatively and postoperatively. Analysis of the difference between groups was performed with the Student t-test. P<0.05 was considered statistically significant. Results: The mean uncorrected visual acuity (UCVA) improved from 0.35±0.13 (range, 0.1-0.6) to 0.78±0.19 (range, 0.5-1) in group I and from 0.26±0.19 (range, 0.1-0.5) to 0.7±0.18 (range, 0.4-1) in group II. The increase in UCVA was statistically significant in both groups (P=0.001, both cases). The mean preoperative and postoperative keratometric astigmatism in group I was 2.0±0.48 D (range, 1.5-2.5 D) and 0.8±0.37 D (range, 0.1-1.4 D), respectively. The decrease in keratometric astigmatism was highly statistically significant in group II (P=0.001.). Mean surgically induced astigmatic reduction by vector analysis was 1.47±0.85 D and 2.21±0.97 D in groups I and II respectively. There were no incision-related complications. Conclusions: Paired OCCIs were predictable and effective in

Topographically supported customized ablation for the management of decentered laser in situ keratomileusis.

PubMed

Kymionis, George D; Panagopoulou, Sophia I; Aslanides, Ioannis M; Plainis, Sotiris; Astyrakakis, Nikolaos; Pallikaris, Ioannis G

2004-05-01

To evaluate the efficacy, predictability, and safety of topographically supported customized ablations (TOSCAs) for decentered ablations following laser in situ keratomileusis (LASIK). Prospective nonrandomized clinical trial. Nine patients (11 eyes) with LASIK-induced decentered ablations underwent TOSCA following flap lifting. Topographically supported customized ablation was performed using a corneal topographer to obtain a customized ablation profile, combined with a flying spot laser. Mean follow-up was 9.22 +/- 2.82 months (range 6-12 months). No intra- or postoperative complications were observed. Manifest refraction (spherical equivalent) did not change significantly (pre-TOSCA: -0.14 +/- 1.58 diopters [range, -1.75 to +3.00 diopters] to +0.46 +/- 1.02 diopters [range, -1.00 to +1.75 diopters]; P =.76), whereas there was a statistically significant reduction in the refractive astigmatism (pre-TOSCA: -1.55 +/- 0.60 diopters [range, -3.00 to -0.75 diopters] to -0.70 +/- 0.56 diopters [range, -2.00 to -0.25 diopters]; P =.003). Mean uncorrected visual acuity improved significantly (P <.001) from 0.45 +/- 0.16 (range, 0.2-0.7) to 0.76 +/- 0.29 (range, 0.2-1.2) at last follow-up. Mean best-corrected visual acuity improved from 0.74 +/- 0.22 (range, 0.4-1.0) to 0.95 +/- 0.20 (range, 0.6-1.2; P =.002). Eccentricity showed a statistically significant reduction after TOSCA treatment (pre-TOSCA: 1.59 +/- 0.46 mm [range, 0.88-2.23 mm]; post-TOSCA: 0.29 +/- 0.09 mm [range, 0.18-0.44 mm]; P <.001). In our small sample, enhancement LASIK procedures with TOSCA appear to improve uncorrected and best-corrected visual acuity as well as eccentricity in patients with LASIK-induced decentered ablation.

A sample predictive model for intraocular pressure following laser in situ keratomileusis for myopia and an "intraocular pressure constant".

PubMed

Bahadir Kilavuzoglu, Ayse Ebru; Bozkurt, Tahir Kansu; Cosar, Cemile Banu; Sener, Asım Bozkurt

2017-06-24

To describe a sample predictive model for intraocular pressure (IOP) following laser in situ keratomileusis (LASIK) for myopia and an IOP constant. The records of patients that underwent LASIK for myopia and myopic astigmatism via WaveLight Allegretto Wave Eye-Q 400 Hz excimer laser and Hansatome XP microkeratome were retrospectively reviewed. Patients with no systemic or ocular disease other than myopia or myopic astigmatism were included in the study. Preoperative and postoperative month 1 data and intraoperative data were used to build the predictive model for IOP after LASIK. The IOP constant was calculated by subtracting the predicted IOP from preoperative IOP. The paired samples t test, Pearson's correlation analysis, curve estimation analysis, and linear regression analysis were used to evaluate the study data. The study included 425 eyes in 214 patients with a mean age of 32 ± 7.8 years. Mean spherical equivalent of the attempted correction (SE-ac) was -3.7 ± 1.7 diopters. Mean post-LASIK decrease in IOP was 4.6 ± 2.3 mmHg. The difference between preoperative and postoperative IOP was statistically significant (P < 0.001). SE-ac, preoperative IOP, and central corneal thickness had highly significant effects on postoperative IOP, based on linear regression analysis (P < 0.001 and R 2  = 0.043, P < 0.001 and R 2  = 0.370, and P < 0.001 and R 2  = 0.132, respectively). Regression model was created (F = 127.733, P < 0.001), and the adjusted R 2 value was 0.548. Evaluation of IOP after LASIK is important in myopic patients. The present study described a practical formula for predicting the true IOP with the aid of an IOP constant value in myopic eyes following LASIK.

Measurement of central corneal thickness with optical low-coherence reflectometry and ultrasound pachymetry in normal and post-femtosecond laser in situ keratomileusis eyes.

PubMed

Huang, Jinhai; Liao, Na; Savini, Giacomo; Li, Yuanguang; Bao, Fangjun; Yu, Ye; Yu, Ayong; Wang, Qinmei

2015-02-01

To determine the repeatability and reproducibility of measurements of central corneal thickness (CCT) using optical low-coherence reflectometry (Lenstar LS900; Haag Streit) in normal eyes and post-femtosecond laser in situ keratomileusis (post-FS-LASIK) eyes and evaluate their agreement with ultrasound (US) pachymetry. CCT was measured using Lenstar and US pachymetry sequentially in normal and post-FS-LASIK eyes by 2 experienced observers. Intraoperator repeatability and interoperator reproducibility were assessed by within-subject standard deviation, test-retest repeatability, coefficient of variation (CoV), and intraclass correlation coefficient. Paired t-tests and Bland-Altman plots were used for analyzing agreement between the 2 devices. In this study, 55 healthy subjects and 50 post-FS-LASIK patients were recruited. Test-retest repeatability of Lenstar was within 10 μm, CoV was less than 1.0%, and intraclass correlation coefficient was more than 0.9 in both normal and post-FS-LASIK groups. Mean difference between these methods was 1.4 ± 4.2 μm and -1.7 ± 5.4 μm, respectively. Moreover, measurements of CCT showed narrow 95% limits of agreement (range, normal group: -6.8 and 9.6 μm; post-FS-LASIK group: -12.4 and 8.9 μm), which implied good agreement. Measurements of CCT using Lenstar showed excellent intraoperator repeatability and interoperator reproducibility both in normal eyes and post-FS-LASIK eyes. Measurements of CCT using Lenstar and US pachymetry showed good agreement and both can be used interchangeably.

Combined laser in situ keratomileusis and prophylactic high-fluence corneal collagen crosslinking for high myopia: two-year safety and efficacy.

PubMed

Kanellopoulos, Anastasios John; Asimellis, George

2015-07-01

To evaluate the safety, efficacy, and refractive and keratometric stability of myopic femtosecond laser in situ keratomileusis (LASIK) with concurrent prophylactic high-fluence corneal collagen crosslinking (CXL) compared with the outcomes of standard femtosecond LASIK. Private clinical practice, Athens, Greece. Consecutive randomized prospective comparative study. Eyes that had myopic LASIK or myopic LASIK with concurrent high-fluence CXL were evaluated preoperatively and up to 2 years postoperatively for manifest refraction spherical equivalent (MRSE), refractive astigmatism, visual acuity, corneal keratometry (K), and endothelial cell count. One hundred forty consecutive eyes had myopic LASIK; 65 of the eyes were treated additionally with CXL. In the LASIK-CXL eyes, the mean postoperative MRSE was -0.18 diopter (D) ± 17.0 (SD) from -6.67 ± 2.14 D preoperatively. The postoperative flat K was 37.67 D from 43.92 D, and the steep K was 38.38 D from 45.15 D. The correlation coefficient of SE correction predictability was 0.975. In the LASIK-only eyes, the mean postoperative MRSE was -0.32 ± 0.24 D from -5.49 ± 1.99 D preoperatively. The flat K was 38.04 D from 43.15 D, and the steep K was 38.69 D from 44.03 D. The correlation coefficient of SE correction predictability was 0.968. The differences between the 2 groups at the 20/20 and 20/25 levels were statistically significant (P = .045 and P = .039, respectively). Two-year results indicate that the application of prophylactic CXL concurrently with high-myopic LASIK appears to improve refractive and keratometric stability, presumably by affecting corneal biomechanical properties. Dr. Kanellopoulos is a consultant to Alcon Surgical, Inc., Wavelight Laser Technologie AG, Allergan, Inc., Avedro, Inc., and i-Optics Corp. Dr. Asimellis has no financial or proprietary interest in any material or method mentioned. Copyright © 2015 ASCRS and ESCRS. Published by Elsevier Inc. All rights reserved.

Chronic Electromagnetic Exposure at Occupational Safety Level Does Not Affect the Metabolic Profile nor Cornea Healing after LASIK Surgery

PubMed Central

Dabouis, Vincent; Gentilhomme, Edgar; Vignal, Rodolphe; Bourbon, Fréderic; Fauvelle, Florence; Debouzy, Jean-Claude

2014-01-01

LASIK eye surgery has become a very common practice for myopic people, especially those in the military. Sometimes undertaken by people who need to keep a specific medical aptitude, this surgery could be performed in secret from the hierarchy and from the institute medical staff. However, even though the eyes have been previously described as one of the most sensitive organs to electromagnetic fields in the human body, no data exist on the potential deleterious effects of electromagnetic fields on the healing eye. The consequences of chronic long-lasting radar exposures at power density, in accordance with the occupational safety standards (9.71 GHz, 50 W/m2), were investigated on cornea healing. The metabolic and clinical statuses after experimental LASIK keratotomy were assessed on the different eye segments in a New Zealand rabbit model. The analysis methods were performed after 5 months of exposure (1 hour/day, 3 times/week). Neither clinical or histological examinations, nor experimental data, such as light scattering, 1H-NMR HRMAS metabolomics, 13C-NMR spectra of lipidic extracts, and antioxidant status, evidenced significant modifications. It was concluded that withdrawing the medical aptitude of people working in electromagnetic field environments (i.e., radar operators in the navy) after eye surgery was not justified. PMID:24757560

Safety and efficacy of a hydrogel inlay with laser in situ keratomileusis to improve vision in myopic presbyopic patients: one-year results.

PubMed

Garza, Enrique Barragan; Chayet, Arturo

2015-02-01

To study the safety and efficacy of implanting a hydrogel corneal inlay (Raindrop Near Vision Inlay) concurrently with performing laser in situ keratomileusis (LASIK) to treat myopic presbyopia and to compare the results with results of the same treatment in emmetropic and hyperopic patients. Two private clinics, Tijuana and Monterrey, Mexico. Prospective nonrandomized clinical trial. Bilateral myopic LASIK was performed and a corneal inlay was concurrently implanted in the nondominant eye under a flap created using a femtosecond laser. Primary safety outcomes were the retention of corrected distance (CDVA) and near (CNVA) visual acuities. Efficacy was evaluated on the basis of uncorrected near (UNVA), intermediate (UIVA), and distance (UDVA) visual acuities. A patient questionnaire was used to assess the preoperative and postoperative incidence of visual symptoms, the ability to perform common tasks with no correction, and patient satisfaction with vision. Thirty eyes were enrolled. At each postoperative visit, the mean CDVA and CNVA were within one half line of preoperative measurements and no eye lost 2 or more lines of CDVA. The mean binocular UDVA, UIVA, and UNVA were better than 20/25 Snellen at all postoperative visits. By 6 months, 93% of patients had a binocular Snellen acuity of 20/25 or better across all visual ranges. According to patient questionnaires, 1 year after surgery, visual symptoms were at preoperative levels, 98% of all visual tasks could be easily performed without correction, and 90% of patients were satisfied or very satisfied with their overall vision. A hydrogel corneal inlay with concurrent LASIK was safe and effective for treating myopic presbyopia. Drs. Garza and Chayet are consultants to and investigators for Revision Optics, Inc. Copyright © 2015. Published by Elsevier Inc.

Accuracy of Corneal Power Measurements for Intraocular Lens Power Calculation after Myopic Laser In situ Keratomileusis.

PubMed

Helaly, Hany A; El-Hifnawy, Mohammad A M; Shaheen, Mohamed Shafik; Abou El-Kheir, Amr F

2016-01-01

To evaluate the accuracy of corneal power measurements for intraocular lens (IOL) power calculation after myopic laser in situ keratomileusis (LASIK). The study evaluated 45 eyes with a history of myopic LASIK. Corneal power was measured using manual keratometry, automated keratometry, optical biometry, and Scheimflug tomography. Different hypothetical IOL power calculation formulas were performed for each case. The steepest mean K value was measured with manual keratometry (37.48 ± 2.86 D) followed by automated keratometry (37.31 ± 2.83 D) then optical biometry (37.06 ± 2.98 D) followed by Scheimflug tomography (36.55 ± 3.08). None of the K values generated by Scheimflug tomography were steeper than the measurements from the other 3 instruments. Using equivalent K reading (EKR) 4 mm with the Double-K SRK/T formula, the refractive outcome generated 97.8% of cases within ± 2 D, 80.0% of cases within ± 1 D, and 42.2% of cases within ± 0.5 D. The best combination of formulas was "Shammas-PL + Double-K SRK/T formula using EKR 4 mm." Scheimflug tomography imaging using the Holladay EKR 4 mm improved the accuracy of IOL power calculation in post-LASIK eyes. The best option is a combination of formulas. We recommended the use the combined "Shammas-PL ± Double-K SRK/T formula using EKR 4 mm"h for optical outcomes.

Publications and Presentations of the Ophthalmology Branch, U.S. Air Force School of Aerospace Medicine, 2006-2010

DTIC Science & Technology

2013-12-01

LASER ASSISTED IN SITU KERATOMILEUSIS ( LASIK ) EYES Aaron MT, Gooch JM, Harvey RR, Davis RE, and Tutt RC Abstract: Aviation, Space, and Environmental...AZ; 9-13 May 2010 10. EFFECT OF HIGH ALTITUDE ON LASER ASSISTED IN SITU KERATOMILEUSIS ( LASIK ) EYES Aaron MT, Gooch JM, Harvey RR, Davis RE, and

Manual limbal markings versus iris-registration software for correction of myopic astigmatism by laser in situ keratomileusis.

PubMed

Shen, Elizabeth P; Chen, Wei-Li; Hu, Fung-Rong

2010-03-01

To compare the efficacy and safety of manual limbal markings and wavefront-guided treatment with iris-registration software in laser in situ keratomileusis (LASIK) for myopic astigmatism. National Taiwan University Hospital, Taipei, Taiwan. Eyes with myopic astigmatism had LASIK with a Technolas 217z laser. Eyes in the limbal-marking group had conventional LASIK (PlanoScan or Zyoptix tissue-saving algorithm) with manual cyclotorsional-error adjustments according to 2 limbal marks. Eyes in the iris-registration group had wavefront-guided ablation (Zyoptix) in which cyclotorsional errors were automatically detected and adjusted. Refraction, corneal topography, and visual acuity data were compared between groups. Vector analysis was by the Alpins method. The mean preoperative spherical equivalent (SE) was -6.64 diopters (D) +/- 1.99 (SD) in the limbal-marking group and -6.72 +/- 1.86 D in the iris-registration group (P = .92). At 6 months, the mean SE was -0.42 +/- 0.63 D and -0.47 +/- 0.62 D, respectively (P = .08). There was no statistically significant difference between groups in the astigmatism correction, success, or flattening index values using 6-month postoperative refractive data. The angle of error was within +/-10 degrees in 73% of eyes in the limbal-marking group and 75% of eyes in the iris-registration group. Manual limbal markings and iris-registration software were equally effective and safe in LASIK for myopic astigmatism, showing that checking cyclotorsion by manual limbal markings is a safe alternative when automated systems are not available. Copyright 2010 ASCRS and ESCRS. Published by Elsevier Inc. All rights reserved.

Astigmatism induced by conventional spherical ablation after PRK and LASIK in myopia with astigmatism < 1.00 D

PubMed Central

Christiansen, Steven M; Mifflin, Mark D; Edmonds, Jason N; Simpson, Rachel G; Moshirfar, Majid

2012-01-01

Background The purpose of this study was to evaluate surgically-induced astigmatism after spherical ablation in photorefractive keratectomy (PRK) and laser-assisted in situ keratomileusis (LASIK) for myopia with astigmatism < 1.00 D. Methods The charts of patients undergoing spherical PRK or LASIK for the correction of myopia with minimal astigmatism of <1.00 D from 2002 to 2012 at the John A Moran Eye Center in Salt Lake City, UT, were retrospectively reviewed. Astigmatism was measured by manifest refraction. The final astigmatic refractive outcome at 6 months postoperatively was compared with the initial refraction by Alpins vector analysis. Results For PRK, average cylinder increased from 0.39 ± 0.25 (0.00–0.75) preoperatively to 0.55 ± 0.48 (0.00–1.75) postoperatively (P = 0.014), compared with an increase in LASIK eyes from 0.40 ± 0.27 (0.00–0.75) preoperatively to 0.52 ± 0.45 (0.00–2.00) postoperatively (P = 0.041). PRK eyes experienced an absolute value change in cylinder of 0.41 ± 0.32 (0.00–1.50) and LASIK eyes experienced a change of 0.41 ± 0.31 (0.00–1.50, P = 0.955). Mean surgically-induced astigmatism was 0.59 ± 0.35 (0.00–1.70) in PRK eyes, with an increase in surgically-induced astigmatism of 0.44 D for each additional 1.00 D of preoperative cylinder; in LASIK eyes, mean surgically-induced astigmatism was 0.55 ± 0.32 (0.00–1.80, P = 0.482), with an increase in surgically-induced astigmatism of 0.29 D for each 1.00 D of preoperative cylinder. Conclusion Spherical ablation can induce substantial astigmatism even in eyes with less than one diopter of preoperative astigmatism in both PRK and LASIK. No significant difference in the magnitude of surgically-induced astigmatism was found between eyes treated with PRK and LASIK, although surgically-induced astigmatism was found to increase with greater levels of preoperative astigmatism in both PRK and LASIK. PMID:23277735

Refractive corneal surgery - discharge

MedlinePlus

Nearsightedness surgery - discharge; Refractive surgery - discharge; LASIK - discharge; PRK - discharge ... November 27, 2017. Garg S, McColgin AZ, Steinert RF. LASIK. In: Tasman W, Jaeger EA, eds. Duane's Ophthalmology . ...

Evaluation of the effectiveness of laser in situ keratomileusis and photorefractive keratectomy for myopia: a meta-analysis.

PubMed

Yang, Xin-Jun; Yan, Hong-Tao; Nakahori, Yutaka

2003-08-01

To evaluate the effectiveness of laser in situ keratomileusis (LASIK) and photorefractive keratectomy (PRK) for correcting myopia. Study selection, data extraction, and quality assessment were performed by two of authors independently. Summary odds ratios and 95% confidence intervals were calculated by DerSimonian & Laird random-effects model and Mantel-Haenszel (fixed-effects) model. All calculations were based on an intention-to-treat and per protocol analysis. Five hundred and eighty eyes (476 patients) from 5 randomized controlled trials were included in this study. At > or = 6 months follow-up, by random-effects model, the pooled odds ratios (OR, for LASIK vs. PRK) of postoperative uncorrected visual acuity (UCVA) of 20/20 or better for all trials were 1.31 (95% CI=0.77-2.22) by per protocol analysis and 1.18 (95% CI=0.74-1.88) by intention-to-treat analysis. In the refractive outcome, the pooled OR of the postoperative spherical equivalent refraction within +/-0.5 diopter (D) of emmetropia did not show any statistical significance, for which the OR were 0.75 (95% CI=0.48-1.18) by per protocol analysis and 0.70 (95% CI=0.47-1.04) by intention-to-treat analysis. LASIK and PRK were found to be similarly effective for the correction of myopia from -1.5 to -15.0 D in a greater than 6 month follow-up.

Patient age, refractive index of the corneal stroma, and outcomes of uneventful laser in situ keratomileusis.

PubMed

Patel, Sudi; Alió, Jorge L; Walewska, Anna; Amparo, Francisco; Artola, Alberto

2013-03-01

To determine the influence of age and the corneal stromal refractive index on the difference between the predicted and actual postoperative refractive error after laser in situ keratomileusis (LASIK) and whether the precision of outcomes could be improved by considering age and the refractive index. Vissum Instituto Oftalmologico de Alicante, Alicante, Spain. Case series. Flaps were created using a mechanical microkeratome. The stromal refractive index was measured using a VCH-1 refractometer after flap lifting. Refractive data were obtained 1, 3, and 6 months postoperatively. Uneventful LASIK was performed in 133 eyes. The mean age, refractive index, and applied corrections were 33.4 years ± 9.49 (SD), 1.368 ± 0.006, and -2.43 ± 3.36 diopters (D), respectively. The difference between the predicted and actual postoperative refractive error = 2.315-0.021 age-1.106 refractive index (F = 3.647, r = 0.254, P=.029; n = 109) at 1 month and = 11.820-0.023 age-7.976 refractive index (F = 3.392, r = 0.261, P=.022, n = 106) at 3 months. A correlation between the actual and calculated postoperative refraction improved from r = -0.178 (P=.064; n = 75) to r = -0.418 (P<.001) after considering the true refractive index 6 months postoperatively. The predicted outcomes of LASIK can be improved by inputting the refractive index of the individual corneal stroma. Unexpected outcomes (>0.50 D) of LASIK could be avoided by considering patient age and the refractive index and by adjusting the applied correction accordingly. Copyright © 2012 ASCRS and ESCRS. Published by Elsevier Inc. All rights reserved.

Vision-related quality of life and visual outcomes after small-incision lenticule extraction and laser in situ keratomileusis.

PubMed

Ang, Marcus; Ho, Henrietta; Fenwick, Eva; Lamoureux, Ecosse; Htoon, Hla M; Koh, Jane; Tan, Donald; Mehta, Jodhbir S

2015-10-01

To compare vision-related quality of life (VRQoL) scores and clinical outcomes between small-incision lenticule extraction and laser in situ keratomileusis (LASIK). Singapore National Eye Centre, Singapore. Prospective study. Patients had small-incision lenticule extraction using the Visumax 500 kHz femtosecond laser; or LASIK excimer ablation with the Wavelight Allegretto 400 Hz laser. Primary outcomes were 3-month predictability, efficacy, and safety. Secondary outcomes were intraoperative experience, visual symptoms, and VRQoL (validated Quality of Life Impact of Refractive Correction [QIRC] questionnaire) in 25 a subgroup of patients in each group. Following Rasch analysis, "Functional" and "Emotional," QIRC dimensions were analysed separately. At 3 months, predictability (82.5% versus 85.3%, ±0.5 diopters attempted correction, P =.453), safety index (1.13 ± 0.19 [SD] versus 1.07 ± 0.16, P = .158), and efficacy index (0.91 ± 0.21 versus 0.97 ± 0.19; P = .002) were found when comparing small-incision lenticule extraction (172 eyes) and LASIK (matched 688 eyes). Intraoperative experience between groups was not statistically different; visual fluctuations (P = .020) and episodes of visual blurring (P = .008) were greater after small-incision lenticule extraction than after LASIK at 1 month but not at 3 months. There was no difference in "functional" (66.7 ± 15.7 versus 55.3 ± 22.2, P = .064) and "emotional" (42.7 ± 23.2 versus 37.9 ± 23.8, P = .394) QIRC dimensions between the 2 groups (25 patients in each group) at 3 months. The study, 3-month predictability, safety, and VRQL scores were not statistically different between small-incision lenticule extraction and LASIK. No author has a financial or proprietary interest in any material or method mentioned. Copyright © 2015 ASCRS and ESCRS. Published by Elsevier Inc. All rights reserved.

Two-years results of small-incision lenticule extraction and wavefront-guided laser in situ keratomileusis for Myopia.

PubMed

Kobashi, Hidenaga; Kamiya, Kazutaka; Igarashi, Akihito; Takahashi, Masahide; Shimizu, Kimiya

2018-03-01

To compare the 2-years visual and refractive outcomes between small-incision lenticule extraction (SMILE) and wavefront-guided laser in situ keratomileusis (LASIK) in eyes with myopia and myopic astigmatism. Our retrospective case-control study examined 30 eyes of 30 patients with the manifest refraction spherical equivalent (MRSE) of -3.71 ± 1.83 dioptres (D) who underwent SMILE and 30 eyes of 30 patients with MRSE of -3.81 ± 1.40 D who underwent wavefront-guided LASIK. We assessed the 2-years clinical outcomes. Logarithm of the minimal angle of resolution (LogMAR)-corrected distance visual acuity (CDVA) was -0.23 ± 0.07 in the SMILE group and -0.24 ± 0.07 in the wavefront-guided LASIK group 2 years postoperatively (p = 0.82). Logarithm of the minimal angle of resolution-uncorrected distance visual acuity (UDVA) was -0.18 ± 0.09 and -0.15 ± 0.11 (p = 0.30, respectively). In the SMILE and wavefront-guided LASIK groups 2 years postoperatively, 100% and 73% of eyes, respectively, were within 0.5 D of the prompted MRSE correction (p = 0.005). Changes in the MRSE of -0.10 ± 0.30 D and -0.23 ± 0.51 D occurred from 3 months to 2 years (p = 0.40, respectively). We found a significant correlation between myopic regression and the changes in the keratometric readings from 3 months to 2 years after wavefront-guided LASIK (r = -0.48, p = 0.002), but not after SMILE (r = -0.004, p = 0.90). Small-incision lenticule extraction offers better refractive outcomes than wavefront-guided LASIK during a 2-years follow-up for the correction of myopia and myopic astigmatism. © 2017 Acta Ophthalmologica Scandinavica Foundation. Published by John Wiley & Sons Ltd.

Contrasting cellular damage after Blue-IRIS and Femto-LASIK in cat cornea.

PubMed

Wozniak, Kaitlin T; Elkins, Noah; Brooks, Daniel R; Savage, Daniel E; MacRae, Scott; Ellis, Jonathan D; Knox, Wayne H; Huxlin, Krystel R

2017-12-01

Blue-intra-tissue refractive index shaping (Blue-IRIS) is a new approach to laser refractive correction of optical aberrations in the eye, which alters the refractive index of the cornea rather than changing its shape. Before it can be implemented in humans, it is critical to establish whether and to what extent, Blue-IRIS damages the cornea. Here, we contrasted the impact of -1.5 D cylinder refractive corrections inscribed using either Blue-IRIS or femtosecond laser in-situ keratomileusis (femto-LASIK) on corneal cell viability. Blue-IRIS was used to write a -1.5 D cylinder gradient index (GRIN) lens over a 2.5 mm by 2.5 mm area into the mid-stromal region of the cornea in six freshly-enucleated feline eyes. The same correction (-1.5 D cylinder) was inscribed into another four cat eyes using femto-LASIK. Six hours later, all corneas were processed for histology and stained for terminal deoxynucleotidyl transferase-mediated dUTP-digoxigenin nick end labeling (TUNEL) and p-γ-H2AX to label damaged cells. In Blue-IRIS-treated corneas, no tissue was removed and TUNEL-stained cells were confined to the laser focal zone in the stroma. In femto-LASIK, photoablation removed 14 μm of anterior stroma, but in addition, TUNEL-positive cells clustered across the femto-flap, the epithelium at the flap edges and the stroma below the ablation zone. Keratocytes positive for p-γ-H2AX were seen adjacent to all Blue-IRIS focal zones, but were completely absent from femto-LASIK-treated corneas. Unlike femto-LASIK, Blue-IRIS attains refractive correction in the cornea without tissue removal and only causes minimal, localized keratocyte death within the laser focal zones. In addition, Blue-IRIS induced DNA modifications associated with phosphorylation of γ-H2AX in keratocytes adjacent to the laser focal zones. We posit that this p-γ-H2AX response is related to alterations in chromatin structure caused by localized changes in osmolarity, a possible mechanism for the induced

Evaluation of point-of-care test for elevated tear matrix metalloproteinase 9 in post-LASIK dry eyes.

PubMed

Chan, Tommy C Y; Ye, Cong; Chan, Kwok Ping; Chu, Kai On; Jhanji, Vishal

2016-09-01

To evaluate the performance of a point-of-care test for detection of matrix metalloproteinase 9 (MMP-9) levels in post-laser-assisted in situ keratomileusis (LASIK) dry eyes. A comparative study between patients with mild to moderate post-LASIK dry eyes and age-matched normal subjects was conducted. Ocular surface disease index (OSDI), tear break-up time (TBUT), and tear film MMP-9 and total protein levels were compared between the two groups. A point-of-care test device (RPS InflammaDry, Sarasota, Florida, USA) was utilised to confirm elevated MMP-9 levels in tear film. Fourteen post-LASIK dry eyes and 34 normal eyes were included. There was no significant difference in age and gender between both groups (p>0.175). The OSDI was significantly higher (25.5±7.7 vs 7.4±2.5; p<0.001) and TBUT levels were significantly lower (5.4±0.9 vs 13.5±2.3; p<0.001) in patients with dry eye compared with normal subjects. The tear film MMP-9 levels were 52.7±32.5 ng/mL in dry eyes and 4.1±2.1 ng/mL in normal eyes (p<0.001). MMP-9 levels were >40 ng/mL in 7/14 (50.0%) post-LASIK dry eyes. The InflammaDry was positive in 8/14 (57.1%) post-LASIK eyes. All positive cases had tear film MMP-9 levels ≥38.03 ng/mL. Agreement between InflammaDry and MMP-9 was excellent with Cohen κ value of 0.857 in post-LASIK dry eyes. Only half of post-LASIK dry eyes were found to have significant inflammation associated with elevated MMP-9. The OSDI is useful to non-specifically identify patients with symptomatic dry eye while the InflammaDry determined which patients with dry eye were associated with significant inflammation that may guide therapeutic management decisions. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://www.bmj.com/company/products-services/rights-and-licensing/

Laser in situ keratomileusis for astigmatism ≤ 0.75 Diopter combined with low myopia: a retrospective data analysis

PubMed Central

2014-01-01

Background This study examined the refractive and visual outcome of wavefront-optimized laser in situ keratomileusis (LASIK) in eyes with low myopia and compound myopic astigmatism ≤ 0.75 diopter (D). Methods 153 eyes from 153 consecutive myopic patients (74 male, 79 female; mean age at surgery 40.4 ± 10.4 years) who had a preoperative refractive cylinder ≤ 0.75 D and a manifest sphere between -0.25 D and -2.75 D, and who had completed 4-month follow-up. Three subgroups defined by the magnitude of preoperative manifest refractive cylinder (0.25, 0.50, and 0.75 D) were formed. Manifest refraction, uncorrected and corrected visual acuity were assessed pre- and postoperatively. The astigmatic changes achieved were determined using the Alpins vector analysis. Results After 4 months (120.0 ± 27.6 days) of follow-up, a mean uncorrected distant visual acuity of 0.07 ± 0.11 logMAR and a mean manifest refraction spherical equivalent of -0.06 ± 0.56 D were found. There was no statistically significant difference in efficacy and safety between the preoperative cylinder groups. Astigmatic overcorrection for preoperative cylinder of ≤ 0.50 D was suggested by the correction index, the magnitude of error, the index of success, and the flattening index. Conclusions Low myopic eyes with a preoperative cylinder of ≤ 0.50 D were significantly overcorrected with regard to cylinder correction when combined with low myopic LASIK. Accordingly, we are cautious in recommending full astigmatic correction for eyes with low myopia and manifest cylinder of ≤ 0.50 D. PMID:24393469

Tracker-assisted versus manual ablation zone centration in laser in situ keratomileusis for myopia and astigmatism.

PubMed

Pineros, Oscar E

2002-01-01

Eye tracker systems have been developed concomitantly with small scanning beams to theoretically reduce ablation zone decentration and for accurate registration of all the laser pulses on the cornea. The purpose of the study was to compare the tracker-assisted with the manual centration method. Twenty-five patients (48 eyes) with myopia and/or astigmatism had laser in situ keratomileusis (LASIK) between August 1998 and February 1999 with the Technolas 117C laser. Twenty patients (38 eyes, 80%) were available for follow-up at 3 months after surgery. Eyes were assigned randomly to one of two ablation zone centration methods: Group 1: Tracker-assisted (20 eyes), Group 2: Manual (18 eyes). Mean distance between the ablation zone center and the pupillary center in the tracker-assisted centration group was 0.55 +/- 0.30 mm (range, 0.10 to 1.4 mm), and in the manual centration group, 0.43 +/- 0.23 mm (range, 0.10 to 1.0 mm) (P = .177). There was no statistically significant difference in postoperative contrast sensitivity, glare, and Topographical Corneal Surface Regularity Index (SRI) between the two groups. We obtained good results with both centration methods. We did not find superiority of the tracker-assisted over manual regarding ablation zone centration, vision quality, or regularity of the ablation.

Laser in situ keratomileusis for high hyperopia with corneal vertex centration and asymmetric offset.

PubMed

de Ortueta, Diego; Arba-Mosquera, Sam

2017-03-10

To investigate refractive outcomes and induction of corneal higher order aberrations (HOA) in eyes that underwent laser-assisted in situ keratomileusis (LASIK) for high hyperopia correction using an aberration neutral profile with corneal vertex centration and asymmetric offset. A total of 24 consecutive patients (38 eyes) who underwent LASIK by one surgeon using AMARIS 750S excimer laser and a Carriazo-Pendular microkeratome for flap creation were retrospectively analyzed. Eyes targeted for plano and with correction in the maximum hyperopic meridian strictly higher than +4D were included in the retrospective analysis. Patients were reviewed at 1, 3, and 6 months postoperatively. Postoperative monocular corrected distance visual acuity (CDVA) and uncorrected distance visual acuity (UDVA), manifest refraction, and corneal wavefront aberrations were compared with respective preoperative metrics. Mean preoperative spherical equivalent and refractive astigmatism was +4.07 ± 0.90 D and 1.37 ± 1.26 D, respectively, reducing to +0.28 ± 0.58D (p<0.0001) and 0.49 ± 0.47 D (p = 0.0001) at the last postoperative visit. Six months postoperatively, 78% of eyes achieved a UDVA of 20/25 or better. No eye lost more than 2 Snellen lines of CDVA at any follow-up. There was a statistically significant induction of vertical trefoil (+0.104 ± 0.299 µm, p<0.05), vertical coma (-0.181 ± 0.463 µm, p<0.01), horizontal coma (+0.198 ± 0.663 µm, p<0.05), spherical aberration (-0.324 ± 0.281 µm, p<0.0001), secondary vertical trefoil (+0.018 ± 0.044 µm, p<0.01), and secondary horizontal coma (+0.026 ± 0.083 µm, p<0.05). Laser-assisted in situ keratomileusis for high hyperopia using corneal vertex centration with asymmetric offset results in significant improvement in refraction and visual acuity although affected by significant induction of some higher order aberrations.

Refractive and Aberration Outcomes after Customized Photorefractive Keratectomy in Comparison with Customized Femtosecond Laser

PubMed Central

Sajjadi, Valleh; Ghoreishi, Mohammad; Jafarzadehpour, Ebrahim

2015-01-01

To compare the refractive and visual outcomes and higher order aberrations in patients with low to moderate myopia who underwent customized photorefractive keratectomy (PRK) or femtosecond laser in situ keratomileusis (Femto-LASIK) this research performed. This study includes data of 120 consecutive eyes of 60 patients with myopia between -3.00 D and -7.00 D with or without astigmatism in two surgery groups: PRK and Femto-LASIK. Refractive, visual, and aberration outcomes of the two methods of surgery were compared after 6 months of follow-up. After six months of follow-up, sphere and cylinder were found significantly decreased and there was no statistically significant difference between the two groups. The mean of uncorrected distance visual acuity in LogMar format for the PRK and Femto-LASIK groups was -0.03±0.07 and -0.01±0.08, respectively, which was not significantly different between the two groups. Higher orders and spherical aberrations increased in both groups significantly, while total aberrations decreased in both groups. After surgery, no differences were observed between the two groups in the amount of aberrations. In conclusion, Both PRK and Femto-LASIK are effective and safe in correcting myopia. In this study PRK induced more spherical and higher order aberrations than Femto-LASIK. PMID:27800501

Scheimpflug topographical changes after Femtosecond LASIK for mixed astigmatism - theoretical aspects and case study.

PubMed

Tabacaru, Bogdana; Stanca, Horia Tudor

2017-01-01

Objective: To evaluate the corneal topographical changes after Femtosecond-LASIK surgery in eyes with mixed astigmatism. Methods: We present the analysis of the corneal Scheimpflug topographies of a patient treated with Femtosecond-LASIK technique for bilateral mixed astigmatism. Results: Three-dimensional reconstruction maps and differential anterior curvature maps were used to demonstrate the ablation profile and its stability in time. Conclusions: Visual and refractive results were very good after surgery, being topographically confirmed by the corneal reshaping which was performed as planned, the achieved ablation being stable during the one-year follow-up period.

The assessment of the stability of the corneal structure after LASIK correction of myopia by different optical zone diameters.

PubMed

Milivojević, Milorad; Petrović, Vladimir; Vukosavljević, Miroslav; Marjanović, Ivan; Resan, Mirko

2016-06-01

Enlargement of optical zone (OZ) diameter during laser in situ keratomileusis (LASIK) correction of myopia postoperatively improves the optical outcome, however, it also leads to the increased stroma tissue consumption--progressive corneal thinning. The aim of this investigation was to present the possibility of safe OZ enlargement without impairing the structural stability of the cornea, while obtaining an improved optical outcome with LASIK treatment of short-sightedness. Preoperative assessment of the cornea structure and prediction of the ablated stroma tissue consumption was conducted in 37 patients (74 eyes) treated for short-sightedness by means of the LASIK method. With the eyes that, according to their cornea structure, had the capacity for OZ diameter enlargement of 0.5 mm, LASIK treatment was performed within the wider OZ diameter of 7.0 mm compared to the standard 6.5 mm. The following two groups were formed, depending on the diameter of the utilized OZ: the group I (the eyes treated with the OZ 6.5 mm, n = 37) and the group II (the eyes treated with the OZ 7.0 mm, n = 37). No significant difference in the observed structural parameters of the cornea was detected between the groups of patients treated with different OZ diameters. The values of all the parameters were significantly bellow the threshold values for the development of postoperative ectasia. Diameter enlargement of the treated OZ, if there is a preoperative cornea capacity for such enlargement, will not impair the postoperative stability of the cornea structure, and will significantly improve the optical outcome.

Safety, efficacy, and predictability of laser in situ keratomileusis to correct myopia or myopic astigmatism with a 750 Hz scanning-spot laser system.

PubMed

Tomita, Minoru; Watabe, Miyuki; Yukawa, Satoshi; Nakamura, Nobuo; Nakamura, Tadayuki; Magnago, Thomas

2014-02-01

To evaluate the clinical outcomes of laser in situ keratomileusis (LASIK) to correct myopia or myopic astigmatism using the Amaris 750S 750 Hz excimer laser. Private LASIK center, Tokyo, Japan. Case series. Patients with myopia or myopic astigmatism (spherical equivalent -0.50 to -11.63 diopters [D]), a corrected distance visual acuity (CDVA) of 20/20 or better, and an estimated residual bed thickness of 300 μm or more had LASIK using the aspheric aberration-free ablation profile of the 750 Hz scanning-spot laser and the Femto LDV Crystal Line femtosecond laser for flap creation. Study parameters included uncorrected distance visual acuity (UDVA), CDVA, manifest refraction, astigmatism, and higher-order aberrations (HOAs). The study included 1280 eyes (685 patients). At 3 months, 96.6% of eyes had a UDVA of 20/20 or better and 99.1% had 20/32 or better; 94.1% of eyes were within ± 0.50 D of the intended correction and 98.9% were within ± 1.00 D; 89.7% of eyes had no residual cylinder and 96.0% had a postoperative astigmatism of less than 0.50 D. All eyes had a postoperative CDVA of 20/20 or better. The HOAs increased postoperatively (P<.001), with mean total postoperative corneal and ocular HOAs of 0.66 μm ± 0.20 (SD) and 0.56 ± 0.23 μm, respectively. The efficacy index and safety index were 1.02 and 1.06, respectively. Laser in situ keratomileusis with the 750 Hz scanning-spot laser was safe, effective, and predictable. No specific clinical side effects that might be associated with a high repetition rate occurred. Mr. Magnago is an employee of Schwind eye-tech-solutions GmbH. No other author has a financial or proprietary interest in any material or method mentioned. Copyright © 2013 ASCRS and ESCRS. Published by Elsevier Inc. All rights reserved.

LASIK for spherical refractive myopia: effect of topographic astigmatism (ocular residual astigmatism, ORA) on refractive outcome.

PubMed

Frings, Andreas; Richard, Gisbert; Steinberg, Johannes; Skevas, Christos; Druchkiv, Vasyl; Katz, Toam; Linke, Stephan J

2015-01-01

In eyes with a preoperative plano refractive cylinder, it would appear that there is no rationale for astigmatic treatment. The aim of this retrospective, cross-sectional data analysis was to determine the amount of topographic astigmatism in refractive plano eyes that results in reduced efficacy after myopic laser in situ keratomileusis (LASIK). This study included 267 eyes from 267 consecutive myopic patients with a refractive plano cylinder. Receiver operating characteristic analysis was used to find the cut-off values of preoperative ocular residual astigmatism (= topographic astigmatism) that can best discriminate between groups of efficacy and safety indices in preoperative plano refractive cylinder eyes. Preoperative ocular residual astigmatism (ORA) (or topographic astigmatism) of ≤0.9 diopters (D) resulted in an efficacy index of at least 0.8 statistically significantly more frequently than eyes with a preoperative ORA of >0.9 D. Eyes with a high ORA preoperatively also had a high ORA postoperatively. Regression analysis showed that each diopter of preoperative ORA reduced efficacy by 0.07. A preoperative corneal astigmatism of ≥0.9 D could (partially) be taken into account in the LASIK design, even if the subjective refractive astigmatism is neutral.

Vector analysis of astigmatic correction after small-incision lenticule extraction and femtosecond-assisted LASIK for low to moderate myopic astigmatism.

PubMed

Chan, Tommy C Y; Ng, Alex L K; Cheng, George P M; Wang, Zheng; Ye, Cong; Woo, Victor C P; Tham, Clement C Y; Jhanji, Vishal

2016-04-01

To compare astigmatic correction between femtosecond-assisted laser in situ keratomileusis (LASIK) and small-incision lenticule extraction (SMILE). A total of 111 patients were included in this prospective study. Fifty-seven eyes were treated with LASIK and 54 eyes were treated with SMILE for myopia with low to moderate (-0.25 to -4.0 D) astigmatism. Uncorrected distance visual acuity (UDVA), corrected distance visual acuity and manifest refraction were measured preoperatively and at 1 and 3 months postoperatively. Visual and refractive outcomes were reported. Changes in refractive astigmatism were evaluated using vector analysis. Preoperative characteristics were similar between both groups. The UDVA at 1 and 3 months was better in the LASIK group compared with the SMILE group (p<0.009). Postoperative cylinder was higher in the SMILE group (p<0.001). Fewer eyes attained the attempted cylindrical correction in the SMILE group (p<0.029). Vector analysis showed no significant difference in target-induced astigmatism (p=0.091) and angle of error (p>0.596) between the two groups. Surgically induced astigmatism was significantly lower in the SMILE group (p<0.023), while the difference vector (p<0.001) and absolute angle of error (p<0.016) were significantly higher in the SMILE group. No significant difference was found in these parameters between 1 and 3 months in both groups (p>0.122). Our results showed that SMILE offered a less favourable astigmatic correction comparable to femtosecond-assisted LASIK in eyes with low to moderate myopic astigmatism. The alignment of treatment was more variable in SMILE, leading to a lower efficacy compared with LASIK by 3 months postoperatively. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://www.bmj.com/company/products-services/rights-and-licensing/

Femtosecond all-solid-state laser for refractive surgery

NASA Astrophysics Data System (ADS)

Zickler, Leander; Han, Meng; Giese, G.'nter; Loesel, Frieder H.; Bille, Josef F.

2003-06-01

Refractive surgery in the pursuit of perfect vision (e.g. 20/10) requires firstly an exact measurement of abberations induced by the eye and then a sophisticated surgical approach. A recent extension of wavefront measurement techniques and adaptive optics to ophthalmology has quantitatively characterized the quality of the human eye. The next milestone towards perfect vision is developing a more efficient and precise laser scalpel and evaluating minimal-invasive laser surgery strategies. Femtosecond all-solid-state MOPA lasers based on passive modelocking and chirped pulse amplification are excellent candidates for eye surgery due to their stability, ultra-high intensity and compact tabletop size. Furthermore, taking into account the peak emission in the near IR and diffraction limited focusing abilities, surgical laser systems performing precise intrastromal incisions for corneal flap resection and intrastromal corneal reshaping promise significant improvement over today's Photorefractive Keratectomy (PRK) and Laser Assisted In Situ Keratomileusis (LASIK) techniques which utilize UV excimer lasers. Through dispersion control and optimized regenerative amplification, a compact femtosecond all-solid-state laser with pulsed energy well above LIOB threshold and kHz repetition rate is constructed. After applying a pulse sequence to the eye, the modified corneal morphology is investigated by high resolution microscopy (Multi Photon/SHG Confocal Microscope).

Correlation between Post-LASIK Starburst Symptom and Ocular Wavefront Aberrations

NASA Astrophysics Data System (ADS)

Liu, Yong-Ji; Mu, Guo-Guang; Wang, Zhao-Qi; Wang-Yan

2006-06-01

Monochromatic aberrations in post laser in-situ keratomileusis (LASIK) eyes are measured. The data are categorized into reference group and starburst group according to the visual symptoms. Statistic analysis has been made to find the correlation between the ocular wavefront aberrations and the starburst symptom. The rms aberrations of the 3rd and 4th orders for the starburst group are significantly larger than those for the reference group. The starburst symptom shows a strong correlation with vertical coma, total coma, spherical aberrations. For 3-mm pupil size and 5.8-mm pupil size, the modulation transfer function (MTF) of the starburst group are lower than those of the reference group, but their visual acuities are close. MTF and PSF analyses are made for two groups, and the results are consistent with the statistical analysis, which means the difference between the two groups is mainly due to the third- and fourth-order Zernike aberrations.

Evaluation of iris recognition system for wavefront-guided laser in situ keratomileusis for myopic astigmatism.

PubMed

Ghosh, Sudipta; Couper, Terry A; Lamoureux, Ecosse; Jhanji, Vishal; Taylor, Hugh R; Vajpayee, Rasik B

2008-02-01

To evaluate the visual and refractive outcomes of wavefront-guided laser in situ keratomileusis (LASIK) using an iris recognition system for the correction of myopic astigmatism. Centre for Eye Research Australia, Melbourne Excimer Laser Research Group, and Royal Victorian Eye and Ear Hospital, East Melbourne, Victoria, Australia. A comparative analysis of wavefront-guided LASIK was performed with an iris recognition system (iris recognition group) and without iris recognition (control group). The main parameters were uncorrected visual acuity (UCVA), best spectacle-corrected visual acuity, amount of residual cylinder, manifest spherical equivalent (SE), and the index of success using the Alpins method of astigmatism analysis 1 and 3 months postoperatively. A P value less than 0.05 was considered statistically significant. Preoperatively, the mean SE was -4.32 diopters (D) +/- 1.59 (SD) in the iris recognition group (100 eyes) and -4.55 +/- 1.87 D in the control group (98 eyes) (P = .84). At 3 months, the mean SE was -0.05 +/- 0.21 D and -0.20 +/- 0.40 D, respectively (P = .001), and an SE within +/-0.50 D of emmetropia was achieved in 92.0% and 85.7% of eyes, respectively (P = .07). At 3 months, the UCVA was 20/20 or better in 90.0% and 76.5% of eyes, respectively. A statistically significant difference in the amount of astigmatic correction was seen between the 2 groups (P = .00 and P = .01 at 1 and 3 months, respectively). The index of success was 98.0% in the iris recognition group and 81.6% in the control group (P = .03). Iris recognition software may achieve better visual and refractive outcomes in wavefront-guided LASIK for myopic astigmatism.

Reliability of Entire Corneal Thickness Mapping in Normal Post-Laser in situ Keratomileusis and Keratoconus Eyes Using Long Scan Depth Spectral Domain Optical Coherence Tomography.

PubMed

Xu, Zhe; Chen, Sisi; Yang, Chun; Huang, Shenghai; Shen, Meixiao; Wang, Yuanyuan

2018-01-01

To investigate the repeatability and reproducibility of mapping the entire corneal thickness using spectral domain optical coherence tomography (SD-OCT). Thirty normal eyes, 30 post-laser in situ keratomileusis (LASIK) surgery eyes, and 30 keratoconus eyes were analyzed. A custom-built long scan depth SD-OCT device was used to obtain entire corneal images. Ten-millimeter-diameter corneal thickness maps were generated by an automated segmentation algorithm. Intraclass correlation coefficients of repeatability (ICC1) and reproducibility (ICC2), and coefficients of repeatability (CoR1) and reproducibility (CoR2), were calculated to quantify the precision and accuracy of corneal pachymetry measurements using the Bland-Altman method. For SD-OCT measurements in healthy subjects, CoR1 and CoR2 were less than 5.00 and 5.53 μm. ICC1 and ICC2 were more than 0.997 and 0.996. For SD-OCT measurements in LASIK patients, CoR1 and CoR2 were less than 5.09 and 5.34 μm. ICC1 and ICC2 were more than 0.997 and 0.996. For SD-OCT measurements in keratoconus patients, CoR1 and CoR2 were less than 11.57 and 10.92 μm. ICC1 and ICC2 were more than 0.995 and 0.996. The measurements of corneal pachymetric mapping by long scan depth SD-OCT can be assessed over the entire corneal area with good repeatability and reproducibility. © 2017 S. Karger AG, Basel.

What Should I Expect Before, During, and After Surgery?

MedlinePlus

... Medical Devices Products and Medical Procedures Surgery Devices LASIK What should I expect before, during, and after ... Surgery If you decide to go ahead with LASIK surgery, you will need an initial or baseline ...

Factors Influencing Intraocular Pressure Changes after Laser In Situ Keratomileusis with Flaps Created by Femtosecond Laser or Mechanical Microkeratome.

PubMed

Lin, Meng-Yin; Chang, David C K; Shen, Yun-Dun; Lin, Yen-Kuang; Lin, Chang-Ping; Wang, I-Jong

2016-01-01

The aim of this study is to describe factors that influence the measured intraocular pressure (IOP) change and to develop a predictive model after myopic laser in situ keratomileusis (LASIK) with a femtosecond (FS) laser or a microkeratome (MK). We retrospectively reviewed preoperative, intraoperative, and 12-month postoperative medical records in 2485 eyes of 1309 patients who underwent LASIK with an FS laser or an MK for myopia and myopic astigmatism. Data were extracted, such as preoperative age, sex, IOP, manifest spherical equivalent (MSE), central corneal keratometry (CCK), central corneal thickness (CCT), and intended flap thickness and postoperative IOP (postIOP) at 1, 6 and 12 months. Linear mixed model (LMM) and multivariate linear regression (MLR) method were used for data analysis. In both models, the preoperative CCT and ablation depth had significant effects on predicting IOP changes in the FS and MK groups. The intended flap thickness was a significant predictor only in the FS laser group (P < .0001 in both models). In the FS group, LMM and MLR could respectively explain 47.00% and 18.91% of the variation of postoperative IOP underestimation (R2 = 0.47 and R(2) = 0.1891). In the MK group, LMM and MLR could explain 37.79% and 19.13% of the variation of IOP underestimation (R(2) = 0.3779 and 0.1913 respectively). The best-fit model for prediction of IOP changes was the LMM in LASIK with an FS laser.

Factors Influencing Intraocular Pressure Changes after Laser In Situ Keratomileusis with Flaps Created by Femtosecond Laser or Mechanical Microkeratome

PubMed Central

Lin, Meng-Yin; Chang, David C. K.; Shen, Yun-Dun; Lin, Yen-Kuang; Lin, Chang-Ping; Wang, I-Jong

2016-01-01

The aim of this study is to describe factors that influence the measured intraocular pressure (IOP) change and to develop a predictive model after myopic laser in situ keratomileusis (LASIK) with a femtosecond (FS) laser or a microkeratome (MK). We retrospectively reviewed preoperative, intraoperative, and 12-month postoperative medical records in 2485 eyes of 1309 patients who underwent LASIK with an FS laser or an MK for myopia and myopic astigmatism. Data were extracted, such as preoperative age, sex, IOP, manifest spherical equivalent (MSE), central corneal keratometry (CCK), central corneal thickness (CCT), and intended flap thickness and postoperative IOP (postIOP) at 1, 6 and 12 months. Linear mixed model (LMM) and multivariate linear regression (MLR) method were used for data analysis. In both models, the preoperative CCT and ablation depth had significant effects on predicting IOP changes in the FS and MK groups. The intended flap thickness was a significant predictor only in the FS laser group (P < .0001 in both models). In the FS group, LMM and MLR could respectively explain 47.00% and 18.91% of the variation of postoperative IOP underestimation (R2 = 0.47 and R2 = 0.1891). In the MK group, LMM and MLR could explain 37.79% and 19.13% of the variation of IOP underestimation (R2 = 0.3779 and 0.1913 respectively). The best-fit model for prediction of IOP changes was the LMM in LASIK with an FS laser. PMID:26824754

[Corneal subbasal nerve density changes after laser in situ keratomileusis with mechanical microkeratome and femtosecond laser].

PubMed

Hu, Liang; Xie, Wenjia; Tang, Lei; Chen, Jia; Zhang, Dong; Yu, Peng; Qu, Jia

2015-01-01

To compare the corneal subbasal nerve density (SND) changes after laser in situ keratomileusis (LASIK) with a microkeratome and a femtosecond laser. Prospective clinical study. Sixty eyes of thirty myopes were included. Fifteen patients (30 eyes) underwent LASIK with the Moria II microkeratome, and the other 15 patients (30 eyes) with the 60 k Hz IntraLase femtosecond laser. Central, temporal and nasal corneal SNDs were measured by confocal microscopy and compared before surgery, 1 month, and 3 months after surgery. Analysis of variance and t test were used for comparing the differences between different time points and two groups. Preoperatively and 1 month, 3 months postoperatively, the SNDs were (16 728.30 ± 4 300.30), (1 875.42 ± 300.50) and (1 701.55 ± 194.11) µm/mm(2) in the central cornea, (11 379.70 ± 1 833.92), (1 341.20 ± 288.68) and (1 860.87 ± 147.60) µm/mm(2) in the temporal cornea, and (8 506.79 ± 662.83), (7 428.96 ± 712.99) and (8 044.32 ± 1 077.54) µm/mm(2) in the nasal cornea, respectively, in the microkeratome group, and (16 351.59 ± 3 503.88), (1 859.38 ± 452.93) and (2 043.67 ± 377.76) in the central cornea, (12 328.22 ± 2 007.43), (1 483.85 ± 371.28) and (2 126.31 ± 279.87) µm/mm(2) in the temporal cornea, and (8 347.91 ± 789.44), (1 475.53 ± 293.98) and (2 022.10 ± 282.89) µm/mm(2) in the nasal cornea, respectively, in the femtosecond laser group. The SNDs at three positions all decreased significantly at each time point postoperatively compared to the baseline values in both groups (1 and 3 months in the microkeratome group: central t = 18.981 and 18.912, temporal t = 30.121 and 27.921, and nasal t = 6.456 and 2.126; in the femtosecond laser group: central t = 22.667 and 22.379, temporal t = 29.000 and 28.376, and nasal t = 46.329 and 41.751; all P < 0.01, except 3 months at the nasal in the microkeratome group, P = 0.042). The nasal SND increased significantly from month 1 to month 3 (t = -3.921, P < 0.01) in the

Induced Higher-order aberrations after Laser In Situ Keratomileusis (LASIK) Performed with Wavefront-Guided IntraLase Femtosecond Laser in moderate to high Astigmatism.

PubMed

Al-Zeraid, Ferial M; Osuagwu, Uchechukwu L

2016-03-22

Wavefront-guided Laser-assisted in situ keratomileusis (LASIK) is a widespread and effective surgical treatment for myopia and astigmatic correction but whether it induces higher-order aberrations remains controversial. The study was designed to evaluate the changes in higher-order aberrations after wavefront-guided ablation with IntraLase femtosecond laser in moderate to high astigmatism. Twenty-three eyes of 15 patients with moderate to high astigmatism (mean cylinder, -3.22 ± 0.59 dioptres) aged between 19 and 35 years (mean age, 25.6 ± 4.9 years) were included in this prospective study. Subjects with cylinder ≥ 1.5 and ≤2.75 D were classified as moderate astigmatism while high astigmatism was ≥3.00 D. All patients underwent a femtosecond laser-enabled (150-kHz IntraLase iFS; Abbott Medical Optics Inc) wavefront-guided ablation. Uncorrected (UDVA), corrected (CDVA) distance visual acuity in logMAR, keratometry, central corneal thickness (CCT) and higher-order aberrations (HOAs) over a 6 mm pupil, were assessed before and 6 months, postoperatively. The relationship between postoperative change in HOA and preoperative mean spherical equivalent refraction, mean astigmatism, and postoperative CCT were tested. At the last follow-up, the mean UDVA was increased (P < 0.0001) but CDVA remained unchanged (P = 0.48) and no eyes lost ≥2 lines of CDVA. Mean spherical equivalent refraction was reduced (P < 0.0001) and was within ±0.50 D range in 61% of eyes. The average corneal curvature was flatter by 4 D and CCT was reduced by 83 μm (P < 0.0001, for all), postoperatively. Coma aberrations remained unchanged (P = 0.07) while the change in trefoil (P = 0.047) postoperatively, was not clinically significant. The 4th order HOAs (spherical aberration and secondary astigmatism) and the HOA root mean square (RMS) increased from -0.18 ± 0.07 μm, 0.04 ± 0.03 μm and 0.47 ± 0.11 μm, preoperatively, to 0.33 ± 0

[Ablation on the undersurface of a LASIK flap. Instrument and method for continuous eye tracking].

PubMed

Taneri, S; Azar, D T

2007-02-01

The risk of iatrogenic keratectasia after laser in situ keratomileusis (LASIK) increases with thinner posterior stromal beds. Ablations on the undersurface of a LASIK flap could only be performed without the guidance of an eye tracker, which may lead to decentration. A new method for laser ablation with flying spot lasers on the undersurface of a LASIK flap was developed that enables the use of an active eye tracker by utilizing a novel instrument. The first clinical results are reported. Patients wishing an enhancement procedure were eligible for a modified repeat LASIK procedure if the flaps cut in the initial procedure were thick enough to perform the intended additional ablation on the undersurface leaving at least 90 microm of flap thickness behind. (1) The horizontal axis and the center of the entrance pupil were marked on the epithelial side of the flap using gentian violet dye. (2) The flap was reflected on a newly designed flap holder which had a donut-shaped black marking. (3) The eye tracker was centered on the mark visible in transparency on the flap. (4) Ablation with a flying spot Bausch & Lomb Technolas 217z laser was performed on the undersurface of the flap with a superior hinge taking into account that in astigmatic ablations the cylinder axis had to be mirrored according to the formula: axis on the undersurface=180 degrees -axis on the stromal bed. (5) The flap was repositioned. Detection of the marking on the modified flap holder and continuous tracking instead of the real pupil was possible in all of the 12 eyes treated with this technique. It may be necessary to cover the real pupil during ablation in order not to confuse the eye tracker. Ablation could be performed without decentration or loss of best spectacle-corrected visual acuity. Refractive results in minor corrections were good without nomogram adjustment. Using this novel flap holder with a marking that is tracked instead of the real pupil, centered ablations with a flying spot laser

Consistent comparison of angle Kappa adjustment between Oculyzer and Topolyzer Vario topography guided LASIK for myopia by EX500 excimer laser.

PubMed

Sun, Ming-Shen; Zhang, Li; Guo, Ning; Song, Yan-Zheng; Zhang, Feng-Ju

2018-01-01

To evaluate and compare the uniformity of angle Kappa adjustment between Oculyzer and Topolyzer Vario topography guided ablation of laser in situ keratomileusis (LASIK) by EX500 excimer laser for myopia. Totally 145 cases (290 consecutive eyes )with myopia received LASIK with a target of emmetropia. The ablation for 86 cases (172 eyes) was guided manually based on Oculyzer topography (study group), while the ablation for 59 cases (118 eyes) was guided automatically by Topolyzer Vario topography (control group). Measurement of adjustment values included data respectively in horizontal and vertical direction of cornea. Horizontally, synclastic adjustment between manually actual values (dx manu ) and Oculyzer topography guided data (dx ocu ) accounts 35.5% in study group, with mean dx manu /dx ocu of 0.78±0.48; while in control group, synclastic adjustment between automatically actual values (dx auto ) and Oculyzer topography data (dx ocu ) accounts 54.2%, with mean dx auto /dx ocu of 0.79±0.66. Vertically, synclastic adjustment between dy manu and dy ocu accounts 55.2% in study group, with mean dy manu /dy ocu of 0.61±0.42; while in control group, synclastic adjustment between dy auto and dy ocu accounts 66.1%, with mean dy auto /dy ocu of 0.66±0.65. There was no statistically significant difference in ratio of actual values/Oculyzer topography guided data in horizontal and vertical direction between two groups ( P =0.951, 0.621). There is high consistency in angle Kappa adjustment guided manually by Oculyzer and guided automatically by Topolyzer Vario topography during corneal refractive surgery by WaveLight EX500 excimer laser.

Intraoperative cyclorotation and pupil centroid shift during LASIK and PRK.

PubMed

Narváez, Julio; Brucks, Matthew; Zimmerman, Grenith; Bekendam, Peter; Bacon, Gregory; Schmid, Kristin

2012-05-01

To determine the degree of cyclorotation and centroid shift in the x and y axis that occurs intraoperatively during LASIK and photorefractive keratectomy (PRK). Intraoperative cyclorotation and centroid shift were measured in 63 eyes from 34 patients with a mean age of 34 years (range: 20 to 56 years) undergoing either LASIK or PRK. Preoperatively, an iris image of each eye was obtained with the VISX WaveScan Wavefront System (Abbott Medical Optics Inc) with iris registration. A VISX Star S4 (Abbott Medical Optics Inc) laser was later used to measure cyclotorsion and pupil centroid shift at the beginning of the refractive procedure and after flap creation or epithelial removal. The mean change in intraoperative cyclorotation was 1.48±1.11° in LASIK eyes and 2.02±2.63° in PRK eyes. Cyclorotation direction changed by >2° in 21% of eyes after flap creation in LASIK and in 32% of eyes after epithelial removal in PRK. The respective mean intraoperative shift in the x axis and y axis was 0.13±0.15 mm and 0.17±0.14 mm, respectively, in LASIK eyes, and 0.09±0.07 mm and 0.10±0.13 mm, respectively, in PRK eyes. Intraoperative centroid shifts >100 μm in either the x axis or y axis occurred in 71% of LASIK eyes and 55% of PRK eyes. Significant changes in cyclotorsion and centroid shifts were noted prior to surgery as well as intraoperatively with both LASIK and PRK. It may be advantageous to engage iris registration immediately prior to ablation to provide a reference point representative of eye position at the initiation of laser delivery. Copyright 2012, SLACK Incorporated.

Hyperopic laser in situ keratomileusis: comparison of femtosecond laser and mechanical microkeratome flap creation.

PubMed

Antonios, Rafic; Arba Mosquera, Samuel; Awwad, Shady T

2015-08-01

To evaluate and compare the refractive predictability and stability of laser in situ keratomileusis (LASIK) flap creation performed with a femtosecond laser and with a mechanical microkeratome to correct mild to moderate hyperopia. American University of Beirut Medical Center, Beirut, Lebanon. Retrospective case series. Patients who had hyperopic LASIK treatment using the Amaris excimer laser were included. Eyes in which the LDV femtosecond laser was used for flap creation were compared with eyes in which the Moria M2 microkeratome was used. The microkeratome group comprised 53 eyes and the femtosecond laser group, 72 eyes. Baseline characteristics were similar between groups (P > .05). The mean spherical equivalent (SE) deviation from target 1 week postoperatively was -0.08 diopter (D) ± 0.58 (SD) in the femtosecond laser group and -0.06 ± 0.87 D in the microkeratome group (P = .92). Thereafter, the mean SE deviation from target increased gradually and by 6 months postoperatively was +0.30 ± 0.50 D and +0.70 ± 0.71 D, respectively (P = .001). The correlation between the achieved and the attempted SE refraction was better in the femtosecond laser group (R(2) = 0.806) than the microkeratome group (R(2) = 0.671). Using the same nomogram, the short-term refractive outcomes of hyperopic LASIK with flap creation performed with the femtosecond laser were comparable to those for the microkeratome; however, the femtosecond group showed significantly better stability over the 6-month follow-up and better predictability, as reflected by a lower standard deviation and stronger Pearson correlation. Dr. Arba Mosquera is an employee of Schwind eye-tech-solutions GmbH and Co. KG. No other author has a financial or proprietary interest in any material or method mentioned. Copyright © 2015 ASCRS and ESCRS. Published by Elsevier Inc. All rights reserved.

Refractive eye surgery - what to ask your doctor

MedlinePlus

... surgery; Nearsightedness surgery - what to ask your doctor; LASIK - what to ask your doctor; Laser-Assisted In ... Academy of Ophthalmology. Questions to ask when considering LASIK. San Francisco, CA. American Academy of Ophthalmology. December ...

LASIK for Spherical Refractive Myopia: Effect of Topographic Astigmatism (Ocular Residual Astigmatism, ORA) on Refractive Outcome

PubMed Central

Frings, Andreas; Richard, Gisbert; Steinberg, Johannes; Skevas, Christos; Druchkiv, Vasyl; Katz, Toam; Linke, Stephan J.

2015-01-01

Purpose In eyes with a preoperative plano refractive cylinder, it would appear that there is no rationale for astigmatic treatment. The aim of this retrospective, cross-sectional data analysis was to determine the amount of topographic astigmatism in refractive plano eyes that results in reduced efficacy after myopic laser in situ keratomileusis (LASIK). Methods This study included 267 eyes from 267 consecutive myopic patients with a refractive plano cylinder. Receiver operating characteristic analysis was used to find the cut-off values of preoperative ocular residual astigmatism (= topographic astigmatism) that can best discriminate between groups of efficacy and safety indices in preoperative plano refractive cylinder eyes. Results Preoperative ocular residual astigmatism (ORA) (or topographic astigmatism) of ≤0.9 diopters (D) resulted in an efficacy index of at least 0.8 statistically significantly more frequently than eyes with a preoperative ORA of >0.9 D. Eyes with a high ORA preoperatively also had a high ORA postoperatively. Regression analysis showed that each diopter of preoperative ORA reduced efficacy by 0.07. Conclusion A preoperative corneal astigmatism of ≥0.9 D could (partially) be taken into account in the LASIK design, even if the subjective refractive astigmatism is neutral. PMID:25875476

Comparison of performances of femtosecond laser and microkeratome for thin-flap laser in situ keratomileusis.

PubMed

Kasetsuwan, Ngamjit; Satitpitakul, Vannarut; Puangsricharern, Vilavun; Reinprayoon, Usanee; Pariyakanok, Lalida

2016-08-01

To compare the clinical outcomes of femtosecond laser (FS) and microkeratome (MK) for thin-flap in situ keratomileusis (LASIK). Data from patients with moderate to high myopia (spherical equivalent, >-4 diopters [D]) who underwent thin-flap LASIK using FS (199 eyes/110 patients) and MK (157 eyes/86 patients) were analyzed in this retrospective study. Preoperative and postoperative data were recorded from day 1 and months 1 and 3, postoperatively. Visual and refractive outcomes were compared for efficacy, safety, predictability, stability, and the efficacy and safety indices. Three months postoperatively, more eyes in the FS group had an uncorrected distance visual acuity (UCVA) of 20/40 or better compared to MK group (relative risk [RR] 1.01, 95% confidence interval [CI], 0.97-1.05, P = 0.58); significantly more eyes in FS group had an UCVA of 20/20 or better (RR, 1.26, 95%CI, 1.08-1.48, P = 0.003). Intraoperative bleeding occurred in 5% and 36.7%, respectively, of FS and MK groups. There were no significant differences in the refractive predictability within spherical equivalents of 0.5 D (FS, 72%; MK, 63%) and 1.0 D (FS, 90%; MK, 86%). Both groups showed good stability 3 months, postoperatively. The efficacy index in FS group was 113.4%; that in MK group was 102.5% at 3 months postoperatively (P < 0.05). The safety indices for FS and MK groups at 3 months postoperatively were 116.4% and 108.2%, respectively (P < 0.05). Both methods of thin-flap created LASIK were effective, safe, predicable, and stable. FS group had significant improvements in efficacy and safety, confirmed by the efficacy and safety indices, compared to MK group. Lasers Surg. Med. 48:596-601, 2016. © 2016 Wiley Periodicals, Inc. © 2016 Wiley Periodicals, Inc.

Scanning laser polarimetry retinal nerve fiber layer thickness measurements after LASIK.

PubMed

Zangwill, Linda M; Abunto, Teresa; Bowd, Christopher; Angeles, Raymund; Schanzlin, David J; Weinreb, Robert N

2005-02-01

To compare retinal nerve fiber layer (RNFL) thickness measurements before and after LASIK. Cohort study. Twenty participants undergoing LASIK and 14 normal controls. Retinal nerve fiber layer thickness was measured before LASIK and approximately 3 months after surgery in one eye each of 20 patients using a scanning laser polarimeter (GDx Nerve Fiber Analyzer) with fixed corneal compensation (FCC), one with variable corneal compensation (GDx VCC), and optical coherence tomography (OCT). Fourteen normal controls also were tested at baseline and approximately 3 months later. Retinal nerve fiber layer thicknesses measured with the GDx FCC, GDx VCC, and OCT. At baseline, mean (95% confidence interval [CI]) RNFL thicknesses for the GDx FCC, GDx VCC, and OCT were 78.1 microm (72.2-83.9), 54.3 microm (52.7-56.0), and 96.8 microm (93.2-100.5), respectively. In both LASIK and control groups, there were no significant changes between baseline and follow-up examinations in GDx VCC and OCT RNFL thickness measurements globally or in the superior and inferior quadrants (mean change, <5 microm for each instrument). In the control group, there also was no significant change in GDx FCC measurements between baseline and follow-up. In LASIK patients, significant reductions were observed in GDx FCC RNFL measurements. Average absolute values of the mean (95% CI) change in thickness were 12.4 microm (7.7-17.2), 15.3 microm (9.6-20.9), and 12.9 microm (7.6-18.1) for GDx FCC RNFL measurements superiorly, inferiorly, and globally, respectively (all Ps < or = 0.001). LASIK does not seem to change RNFL thickness. Reduction in GDx FCC RNFL thickness measurements after LASIK is a measurement artifact and is most likely due to erroneous compensation for corneal birefringence. With scanning laser polarimetry, it is mandatory to compensate individually for change in corneal birefringence after LASIK to ensure accurate RNFL assessment.

Use of market segmentation to identify untapped consumer needs in vision correction surgery for future growth.

PubMed

Loarie, Thomas M; Applegate, David; Kuenne, Christopher B; Choi, Lawrence J; Horowitz, Diane P

2003-01-01

Market segmentation analysis identifies discrete segments of the population whose beliefs are consistent with exhibited behaviors such as purchase choice. This study applies market segmentation analysis to low myopes (-1 to -3 D with less than 1 D cylinder) in their consideration and choice of a refractive surgery procedure to discover opportunities within the market. A quantitative survey based on focus group research was sent to a demographically balanced sample of myopes using contact lenses and/or glasses. A variable reduction process followed by a clustering analysis was used to discover discrete belief-based segments. The resulting segments were validated both analytically and through in-market testing. Discontented individuals who wear contact lenses are the primary target for vision correction surgery. However, 81% of the target group is apprehensive about laser in situ keratomileusis (LASIK). They are nervous about the procedure and strongly desire reversibility and exchangeability. There exists a large untapped opportunity for vision correction surgery within the low myope population. Market segmentation analysis helped determine how to best meet this opportunity through repositioning existing procedures or developing new vision correction technology, and could also be applied to identify opportunities in other vision correction populations.

Do outside temperature and sunlight duration influence the outcome of laser refractive surgery? Results from the Hamburg Weather Study

PubMed Central

Neuhaus-Richard, Ines; Frings, Andreas; Görsch, Isabel Caroline; Druchkiv, Vasyl; Katz, Toam; Linke, Stephan Johannes; Richard, Gisbert

2014-01-01

Purpose To examine the impact of temperature and sunlight duration on refractive and visual outcome of laser-assisted in situ keratomileusis (LASIK) in myopic eyes. Setting University Medical Center Hamburg-Eppendorf, Germany, and Care Vision Refractive Centers, Germany. Design Retrospective, cross-sectional data analysis. Methods This study comprised 1,052 eyes of 1,052 consecutive myopic patients (419 males, 633 females; mean age at surgery 35.0±9.0 years) with a mean preoperative refractive spherical equivalent (SE) of −3.88±1.85 diopters (D). Two subgroups were defined, comprising patients undergoing surgery during either meteorological winter or summer. Manifest refraction, uncorrected, and corrected distant visual acuity (UDVA and CDVA) were assessed pre- and postoperatively. We applied robust regression analysis with efficiency index (EI), safety index (SI), and postoperative SE (in D) as dependent variables. Results At the 1-month (33.0±5.0 days) follow-up, the mean postoperative SE was −0.18±0.44 D. Bivariate comparisons showed that statistically significant better EI was related to days with lower temperature. We obtained a significant difference for SI which suggested that low temperature had a positive influence on SI. No change by more than one line on LogMAR scale was obtained. Conclusion Although being statistically significant, there was no clinically relevant difference in the outcome of LASIK, which demonstrates its highly standardized quality. Prospective, longitudinal studies are warranted to address meteorotropic reactions through evaluating defined meteorological parameters. PMID:24966665

Implantation of a multifocal toric intraocular lens with a surface-embedded near segment after repeated LASIK treatments.

PubMed

Khoramnia, Ramin; Auffarth, Gerd U; Rabsilber, Tanja M; Holzer, Mike P

2012-11-01

We report a 66-year-old patient who presented with increasing hyperopia, astigmatism, and presbyopia in both eyes 8 years after bilateral laser in situ keratomileusis (LASIK) and LASIK enhancement in the left eye aiming for spectacle independence. Bilateral multifocal toric Lentis Mplus intraocular lenses (IOLs) with an embedded near segment and individually customized cylinder correction were implanted uneventfully following phacoemulsification. The Haigis-L formula after previous hyperopia correction was chosen for IOL power calculation and provided reliable results. Emmetropia was targeted and achieved. Three months postoperatively, the uncorrected distance visual acuity had increased from 0.40 logMAR to 0.10 logMAR in the right eye and from 0.20 logMAR to 0.00 logMAR in the left eye. The patient gained 6 lines of uncorrected near visual acuity: 0.20 logMAR in the right eye and 0.10 logMAR in the left eye. This case shows that customized premium IOL implantation can provide accurate results even in challenging cases. The International Vision Correction Research Centre, Department of Ophthalmology, University of Heidelberg, Heidelberg, Germany, has received research grants, lecture fees, and travel reimbursement from Oculentis GmbH. Copyright © 2012 ASCRS and ESCRS. Published by Elsevier Inc. All rights reserved.

Changes in biomechanical properties of the cornea and intraocular pressure after myopic laser in situ keratomileusis using a femtosecond laser for flap creation determined using ocular response analyzer and Goldmann applanation tonometry.

PubMed

Shin, Jonghoon; Kim, Tae Won; Park, Soo Jeong; Yoon, Min; Lee, Ji Woong

2015-03-01

To compare intraocular pressure (IOP) measurements before and after laser in situ keratomileusis (LASIK) using a femtosecond laser for flap creation, and to identify factors that may influence the preoperative and postoperative IOP, and the change in IOP after LASIK. Forty eyes from 20 patients who underwent treatment for myopia using a femtosecond laser for flap creation were enrolled in this study. The IOP and corneal biomechanical markers were prospectively measured preoperatively and 1 month after LASIK with Goldmann applanation tonometry (GAT) and the ocular response analyzer (ORA). Manifest refraction spherical equivalent, central corneal thickness, ablation depth, and mean corneal curvature (K reading) were also recorded. After LASIK, there was a significant reduction in the IOP measurement with respect to the corneal-compensated intraocular pressure (IOPcc) (Δ=-0.67±2.07 mm Hg), Goldmann-correlated pressure (IOPg) (Δ=-3.92±2.19 mm Hg), and GAT (Δ=-2.6±2.51). Multiple regression analysis revealed that the corneal hysteresis (CH) and corneal resistance factor (CRF) are statistically significant predictors of IOPcc, IOPg, and GAT (P<0.000). In this analysis, the preoperative manifest refraction spherical equivalent, CH, and CRF were significant predictors of ΔIOPcc (adjusted R²=0.401) and ΔIOPg (adjusted R²=0.386). The preoperative SE and central corneal thickness significantly predicted ΔGAT (adjusted R²=0.464). ORA provides a more complete measurement of IOP after LASIK with a femtosecond laser than GAT because ORA provides greater knowledge of the corneal biomechanics in terms of CH and CRF.

Corrective Lens Use and Refractive Error Among United States Air Force Aircrew

DTIC Science & Technology

2010-03-01

surgery was approved for aircrew members in August 2000. Initially only photorefractive keratectomy ( PRK ) was approved, but 200 MILITARY MEDICINE, Vol...approval for laser in-situ keratomileusis ( LASIK ), although USAF policy limits CRS treatments on aircrew to no more than 8.00 D of myopia, no more than...Undergraduate Pilot Training Pass/Fail Rate of Spectacled vs . Nonspectacled Student Pilots. Report No. USAFSAM-TR-85-50. Brooks Air Eorce Base, TX, USAE

The Effects of Scattered Light from Optical Components on Visual Function

DTIC Science & Technology

2016-02-01

zones (e.g., 0-5° vs 5-10°) occurs, then the general distribution of scatter, uniform or not, or that some ratio of scatter between different angular...affect the sensitivity of the eye and none reported having refractive surgery within the past year (photorefractive keratectomy ( PRK ) or laser...assisted in situ keratomileusis ( LASIK )). They performed all the visual function tasks monocularly, using the right eye. 2.3 Visual Function Assessment

Measuring patient's expectation and the perception of quality in LASIK services.

PubMed

Lin, Deng-Juin; Sheu, Ing-Cheau; Pai, Jar-Yuan; Bair, Alex; Hung, Che-Yu; Yeh, Yuan-Hung; Chou, Ming-Jen

2009-07-10

LASIK is the use of excimer lasers to treat therapeutic and refractive visual disorders, ranging from superficial scars to nearsightedness (myopia), and from astigmatism to farsightedness (hyperopia). The purposes of this study are to checking the applicability and psychometric properties of the SERVQUAL on Lasik surgery population. Second, use SEM methods to investigate the loyalty, perceptions and expectations relationship on LASIK surgery. The method with which this study was conducted was questionnaire development. A total of 463 consecutive patients, attending LASIK surgery affiliated with Chung Shan Medical University Eye Center, enrolled in this study. All participants were asked to complete revised SERVQUAL questionnaires. Student t test, correlation test, and ANOVA and factor analyses were used to identify the characters and factors of service quality. Paired t test were used to test the gap between expectation and perception scores and structural equation modeling was used to examine relationships among satisfaction components. The effective response rate was 97.3%. Validity was verified by several methods and internal reliability Cronbach's alpha was > 0.958. The results from patient's scores were very high with an overall score of 6.41(0.66), expectations at 6.68(0.47), and perceptions at 6.51(0.57). The gap between expectations and perceptions was significant, however, (t = 6.08). Furthermore, there were significant differences in the expectation scores among the different jobs. Also, the results showed that the higher the education of the patient, the lower their perception score (r = -0.10). The factor loading results of factor analysis showed 5 factors of the 22 items of the SERVQUAL model. The 5 factors of perception explained 72.94% of the total variance there; and on expectations it explained 77.12% of the total variance of satisfaction scores.The goodness-of-fit summary, of structure equation modeling, showed trends in concept on expectations

Measuring patient's expectation and the perception of quality in LASIK services

PubMed Central

Lin, Deng-Juin; Sheu, Ing-Cheau; Pai, Jar-Yuan; Bair, Alex; Hung, Che-Yu; Yeh, Yuan-Hung; Chou, Ming-Jen

2009-01-01

Background LASIK is the use of excimer lasers to treat therapeutic and refractive visual disorders, ranging from superficial scars to nearsightedness (myopia), and from astigmatism to farsightedness (hyperopia). The purposes of this study are to checking the applicability and psychometric properties of the SERVQUAL on Lasik surgery population. Second, use SEM methods to investigate the loyalty, perceptions and expectations relationship on LASIK surgery. Methods The method with which this study was conducted was questionnaire development. A total of 463 consecutive patients, attending LASIK surgery affiliated with Chung Shan Medical University Eye Center, enrolled in this study. All participants were asked to complete revised SERVQUAL questionnaires. Student t test, correlation test, and ANOVA and factor analyses were used to identify the characters and factors of service quality. Paired t test were used to test the gap between expectation and perception scores and structural equation modeling was used to examine relationships among satisfaction components. Results The effective response rate was 97.3%. Validity was verified by several methods and internal reliability Cronbach's alpha was > 0.958. The results from patient's scores were very high with an overall score of 6.41(0.66), expectations at 6.68(0.47), and perceptions at 6.51(0.57). The gap between expectations and perceptions was significant, however, (t = 6.08). Furthermore, there were significant differences in the expectation scores among the different jobs. Also, the results showed that the higher the education of the patient, the lower their perception score (r = -0.10). The factor loading results of factor analysis showed 5 factors of the 22 items of the SERVQUAL model. The 5 factors of perception explained 72.94% of the total variance there; and on expectations it explained 77.12% of the total variance of satisfaction scores. The goodness-of-fit summary, of structure equation modeling, showed trends

Combined hydrogel inlay and laser in situ keratomileusis to compensate for presbyopia in hyperopic patients: one-year safety and efficacy.

PubMed

Chayet, Arturo; Barragan Garza, Enrique

2013-11-01

To perform a feasibility study of the safety and efficacy of a corneal-contouring inlay with concurrent laser in situ keratomileusis (LASIK) to treat hyperopic presbyopia. Private clinic, Tijuana, Mexico. Prospective interventional case series. Hyperopic patients received LASIK in both eyes and a corneal inlay under the femtosecond laser flap in the nondominant eye. The inlay is designed to reshape the anterior corneal curvature, creating a near-center multifocal refractive effect. Main safety outcomes were retention of preoperative corrected distance and near visual acuities and reports of adverse events. Efficacy was determined through measurements of near, intermediate, and distance visual acuities and patient questionnaires on visual task ability and satisfaction. The study enrolled 16 patients. All eyes with an inlay achieved an uncorrected near visual acuity (UNVA) of 20/32 or better by the 1-week postoperative examination and at every visit thereafter. The mean monocular and binocular UNVA was 20/27 or better at all visits. The mean binocular uncorrected distance visual acuity improved significantly from 20/53 preoperatively to 20/19 postoperatively (P<10(-5)). One inlay was explanted during the study. At 1 year, all 14 patients analyzed were satisfied or very satisfied with their near, distance, and overall vision. The hydrogel corneal inlay with concurrent LASIK improved uncorrected near, intermediate, and distance visual acuity in hyperopic presbyopic patients with high patient satisfaction and visual task ability. This represents a new indication for this recently developed technology. Copyright © 2013 ASCRS and ESCRS. Published by Elsevier Inc. All rights reserved.

Corneal Collagen Crosslinking Combined with Phototherapeutic Keratectomy and Photorefractive Keratectomy for Corneal Ectasia after Laser in situ Keratomileusis.

PubMed

Zhu, Wei; Han, Yunfei; Cui, Changxia; Xu, Wenwen; Wang, Xuan; Dou, Xiaoxiao; Xu, Linlin; Xu, Yanyun; Mu, Guoying

2018-01-01

The aim of this study was to analyze the effects of corneal crosslinking (CXL) combined with phototherapeutic keratectomy (PTK) and photorefractive keratectomy (PRK) in halting the progression and improving the visual function of corneal ectasia after laser in situ keratomileusis (LASIK). PTK-PRK-CXL was performed on 14 eyes of 14 patients who developed corneal ectasia after LASIK. The visual acuity, spherical refraction and cylinder, corneal topography indices, thinnest corneal thickness (TCT), and endothelial cell count were evaluated at baseline and at 1, 3, 6, and 12 months postoperatively. The mean uncorrected visual acuity improved significantly from 0.64 ± 0.36 logMAR preoperatively to 0.19 ± 0.12 logMAR at 12 months of follow-up (p < 0.001), while the mean best corrected visual acuity improved from 0.21 ± 0.14 logMAR at baseline to 0.04 ± 0.10 logMAR at 12 months postoperatively (p < 0.001). A significant decrease was observed in Kmax and Kmean values from 52.51 ± 6.74 and 43.55 ± 3.37 D at baseline to 45.72 ± 5.18 (p < 0.001) and 40.60 ± 3.05 D (p < 0.001) at the 1-year follow-up. The mean TCT decreased significantly from 419.07 ± 36.56 µm before treatment to 320.93 ± 39.78 µm at 12 months of follow-up (p < 0.001), and there was no significant endothelial cell loss (p > 0.05) beyond 6 months after treatment. PTK-PRK-CXL is a promising procedure to halt the progression of post-LASIK keratectasia with significant visual quality improvement. © 2018 S. Karger AG, Basel.

Early wound healing of laser in situ keratomileusis-like flaps after treatment with human corneal stromal stem cells.

PubMed

Morgan, Siân R; Dooley, Erin P; Kamma-Lorger, Christina; Funderburgh, James L; Funderburgh, Martha L; Meek, Keith M

2016-02-01

To use a well-established organ culture model to investigate the effects of corneal stromal stem cells on the optical and biomechanical properties of corneal wounds after laser in situ keratomileusis (LASIK)-like flap creation. School of Optometry and Vision Sciences, Cardiff University, Cardiff, Wales, United Kingdom. Experimental study. The LASIK-like flaps were produced in sheep corneas. The flap beds were treated with corneal stromal stem cells and were then replaced and allowed to heal for different periods of up to 3 weeks in organ culture. The optical transmission of the cornea, the force required to detach the flap, and the presence of myofibroblasts near the flap bed were measured. Corneal stromal stem cell-treated flap beds were statistically significantly more transparent after 3 weeks in culture than the untreated controls. At 3 weeks, the mean force necessary to detach the flap was more than twice the force required for the respective control samples. Concurrently, there were 44% activated cells immediately below the flap margin of the controls compared with 29% in the same region of the corneal stromal stem cell-treated flaps. In this system, the presence of corneal stromal stem cells at the wound margin significantly increased the adherence of LASIK-like flaps while maintaining corneal transparency. It is postulated that this is achieved by the deposition of extracellular connective tissue similar to that found in the normal cornea and by the paucity of activated keratocytes (myofibroblasts), which are known to scatter a significant amount of the incident light. No author has a financial or proprietary interest in any material or method mentioned. Copyright © 2016 The Authors. Published by Elsevier Inc. All rights reserved.

Longitudinal measurements of luminance and chromatic contrast sensitivity: comparison between wavefront-guided LASIK and contralateral PRK for myopia.

PubMed

Barboni, Mirella Telles Salgueiro; Feitosa-Santana, Claudia; Barreto Junior, Jackson; Lago, Marcos; Bechara, Samir Jacob; Alves, Milton Ruiz; Ventura, Dora Fix

2013-10-01

The present study aimed to compare the postoperative contrast sensitivity functions between wavefront-guided LASIK eyes and their contralateral wavefront-guided PRK eyes. The participants were 11 healthy subjects (mean age=32.4 ± 6.2 years) who had myopic astigmatism. The spatial contrast sensitivity functions were measured before and three times after the surgery. Psycho and a Cambridge graphic board (VSG 2/4) were used to measure luminance, red-green, and blue-yellow spatial contrast sensitivity functions (from 0.85 to 13.1 cycles/degree). Longitudinal analysis and comparison between surgeries were performed. There was no significant contrast sensitivity change during the one-year follow-up measurements neither for LASIK nor for PRK eyes. The comparison between procedures showed no differences at 12 months postoperative. The present data showed similar contrast sensitivities during one-year follow-up of wave-front guided refractive surgeries. Moreover, one year postoperative data showed no differences in the effects of either wavefront-guided LASIK or wavefront-guided PRK on the luminance and chromatic spatial contrast sensitivity functions.

Initial resident refractive surgical experience: outcomes of PRK and LASIK for myopia.

PubMed

Wagoner, Michael D; Wickard, Joseph C; Wandling, George R; Milder, Lisa C; Rauen, Matthew P; Kitzmann, Anna S; Sutphin, John E; Goins, Kenneth M

2011-03-01

To evaluate and compare the outcome of initial resident surgical experience with photorefractive keratectomy (PRK) and LASIK. Retrospective review of all cases performed with the VISX Star S4 platform (Abbott Medical Optics) between July 1, 2003 and June 30, 2007. Inclusion criteria were spherical equivalent of -0.50 to -10.00 diopters (D), refractive astigmatic error of ≤3.00 D, intention to provide full distance correction, and minimum 3-month postoperative follow-up after initial ablation or retreatment (if performed). A total of 153 cases performed by 20 different residents met the inclusion criteria; 38 eyes underwent PRK and 115 eyes had LASIK. After initial treatment, mean Snellen uncorrected distance visual acuity (UDVA) after PRK was 20/17.3 and after LASIK was 20/19.5. Photorefractive keratectomy was associated with a significantly better approximation between preoperative corrected distance visual acuity (CDVA) and postoperative UDVA (ΔlogMAR 0.009 vs 0.091; P=.004) and a greater percentage of eyes that achieved UDVA of 20/20 or better (94.7% vs 78.3%; P=.02) or 20/30 or better (100% vs 87.8%; P=.02). There was a higher prevalence of retreatment in eyes that underwent LASIK (7.0% vs 0%; P=.20). One (0.9%) eye lost 2 lines of CDVA after LASIK. Supervised refractive surgery residents can achieve excellent visual outcomes in patients operated during their initial refractive experience. Photorefractive keratectomy was associated with better visual outcome than LASIK. Copyright 2011, SLACK Incorporated.

Vector analysis of astigmatism before and after LASIK: a comparison of two different platforms for treatment of high astigmatism.

PubMed

Biscevic, Alma; Bohac, Maja; Koncarevic, Mateja; Anticic, Marija; Dekaris, Iva; Patel, Sudi

2015-12-01

To compare the outcomes of astigmatic laser in-situ keratomileusis (LASIK) procedures between two different platforms using J0 and J45 vector analysis. Patients were divided into four groups, depending on the type of astigmatism and laser platform on which they were treated. Astigmatism was between 2 and 7 diopters (D). One hundred and thirty-five patients with myopic astigmatism (246 eyes) and 102 patients with mixed astigmatism (172 eyes) underwent unremarkable LASIK correction on Wavelight Allegretto Eye-Q 400Hz and Schwind Amaris 750S laser platform. The preoperative and postoperative sphere, negative cylinder [C] and axis (ø) of manifest refractions were subjected to vector analysis by calculations of the standard J0 (cos [4π(ø-90)/360]xC/2) and J45 (sin[4π(ø-90)/360]xC/2). Reporting the key results, we found J0 significantly reduced after LASIK in both groups (p < 0.001) but not J45. There was no significant association between individual pairs of pre and postoperative J0 & J45 values. There was no significant difference between the outcomes of the two platforms. Wavelight Allegretto 400Hz and Schwind Amaris 750S showed excellent results for treating patients with astigmatism, regardless whether it is mixed or myopic astigmatism. The J45 did not reduce significantly possibly because of the low number of eyes with oblique astigmatism. There was no genuine difference post-operatively between groups treated on two different laser platforms according to the vector analyses.

Comparison of astigmatic correction after femtosecond lenticule extraction and wavefront-guided LASIK for myopic astigmatism.

PubMed

Ali, Mohamed A; Kobashi, Hidenaga; Kamiya, Kazutaka; Igarashi, Akihito; Miyake, Toshiyuki; Elewa, Mohamed Ehab M; Komatsu, Mari; Shimizu, Kimiya

2014-12-01

To compare postoperative astigmatic correction between femtosecond lenticule extraction (FLEx) and wavefront-guided LASIK in eyes with myopic astigmatism. Fifty-eight eyes of 41 patients undergoing FLEx and 49 eyes of 29 patients undergoing wavefront-guided LASIK to correct myopic astigmatism were examined. Visual acuity, cylindrical refraction, predictability of the astigmatic correction, and astigmatic vector components were compared between groups 6 months after surgery. There was no statistically significant difference in manifest cylindrical refraction (P = .08) or percentage of eyes within ± 0.50 diopter (D) of its refraction (P = .11) between the surgical procedures. The index of success in FLEx was statistically significantly better than that of wavefront-guided LASIK (P = .02), although there was no significant difference between the groups in other indices (eg, surgically induced astigmatism, target-induced astigmatism, astigmatic correction index, angle of error, difference vector, and flattening index). Subgroup analysis showed that FLEx had a better index of success (P = .02) and difference vector (P = .04) than wavefront-guided LASIK in the low cylinder subgroup; the angle of error in FLEx was significantly smaller than that of wavefront-guided LASIK in the moderate cylinder subgroup (P = .03). Both FLEx and wavefront-guided LASIK worked well for the correction of myopic astigmatism by the 6-month follow-up visit. Although FLEx had a better index of success than wavefront-guided LASIK when using vector analysis, it appears equivalent to wavefront-guided LASIK in terms of visual acuity and the correction of astigmatism. Copyright 2014, SLACK Incorporated.

Comparison of Tear cytokines and clinical outcomes between off-flap and on-flap epi-LASIK with mitomycin C.

PubMed

Zhang, Yu; Chen, Yue-Guo; Xia, Ying-Jie; Qi, Hong

2012-09-01

To compare tear cytokines and clinical outcomes between off-flap and on-flap epi-LASIK eyes and explore the possible mechanism for the clinical differences. This double-masked, randomized study enrolled 18 myopic patients who underwent off-flap epi-LASIK with mitomycin C (MMC) in 1 eye and on-flap epi-LASIK with MMC in the contralateral eye. Tears were collected from each eye preoperatively and 2 hours, 1 day, and 5 days postoperatively. Concentrations of multiple tear cytokines were measured by a multiplex immunobead assay. Uncorrected distance visual acuity (UDVA), refraction, haze scores, pain scores, and percentage of corneal epithelial healing were evaluated. Compared with the on-flap group, the off-flap group had outcomes of better UDVA and higher percentages of epithelial healing at 5 days after surgery (P<.001) and lower levels of haze at 1 month after surgery (P=.049). Preoperatively, no significant differences were noted in the release rate of all tear cytokines between groups. At 2 hours postoperatively, the release rate of tear basic fibroblast growth factor (bFGF), platelet-derived growth factor-BB (PDGF-BB), interleukin-8 (IL-8), and tumor necrosis factor alpha (TNF-α) in the off-flap group were significantly lower than those in the on-flap group (P=.011, .017, .048, and .041, respectively). Off-flap epi-LASIK with MMC offers faster corneal epithelial healing and visual recovery, and temporary less haze than on-flap epi-LASIK with MMC. The lower tear levels of bFGF, PDGF-BB, IL-8, and TNF-α in the offflap group 2 hours after surgery may suggest a possible mechanism for the clinical differences. Copyright 2012, SLACK Incorporated.

Comparative analysis of the efficacy of astigmatic correction after wavefront-guided and wavefront-optimized LASIK in low and moderate myopic eyes

PubMed Central

Khalifa, Mounir A.; Alsahn, Mahmoud F.; Shaheen, Mohamed Shafik; Pinero, David P.

2017-01-01

AIM To evaluate and compare the efficacy of the astigmatic correction achieved with laser in situ keratomileusis (LASIK) in eyes with myopic astigmatism using wavefront-guided (WFG) and wavefront-optimized (WFO) ablation profiles. METHODS Prospective study included 221 eyes undergoing LASIK: 99 and 122 eyes with low and moderate myopic astigmatism (low and moderate myopia groups). Two subgroups were differentiated in each group according to the ablation profile: WFG subgroup, 109 eyes (45/64, low/moderate myopia groups) treated using the Advanced CustomVue platform (Abbott Medical Optics Inc.), and WFO subgroup, 112 eyes (54/58, low/moderate myopia groups) treated using the EX-500 platform (Alcon). Clinical outcomes were evaluated during a 6-month follow-up, including a vector analysis of astigmatic changes. RESULTS Significantly better postoperative uncorrected visual acuity and efficacy index was found in the WFG subgroups of each group (P≤0.041). Postoperative spherical equivalent and cylinder were significantly higher in WFO subgroups (P≤0.003). In moderate myopia group, a higher percentage of eyes with a postoperative cylinder ≤0.25 D was found in the WFG subgroup (90.6% vs 65.5%, P=0.002). In low and moderate myopia groups, the difference vector was significantly higher in the WFO subgroup compared to WFG (P<0.001). In moderate myopia group, the magnitude (P=0.008) and angle of error (P<0.001) were also significantly higher in the WFO subgroup. Significantly less induction of high order aberrations were found with WFG treatments in both low and moderate myopia groups (P≤0.006). CONCLUSION A more efficacious correction of myopic astigmatism providing a better visual outcome is achieved with WFG LASIK compared to WFO LASIK. PMID:28251090

Outcomes of LASIK for Myopia or Myopic Astigmatism Correction with the FS200 Femtosecond Laser and EX500 Excimer Laser Platform

PubMed Central

Niparugs, Muanploy; Tananuvat, Napaporn; Chaidaroon, Winai; Tangmonkongvoragul, Chulaluck; Ausayakhun, Somsanguan

2018-01-01

Purpose: To evaluate the efficacy, predictability, stability and safety of laser in situ keratomileusis (LASIK) using the FS200 femtosecond laser and EX500 excimer laser platform. Methods: The outcomes of 254 eyes of 129 consecutive patients with myopia or myopic astigmatism who underwent full correction femtosecond laser-assisted LASIK at CMU LASIK Center were assessed. Pre-operative and post-operative parameters including manifest refraction, Uncorrected Distance Visual Acuity (UDVA), Best Corrected Distance Visual Acuity (BDVA), corneal topography and tomography were analyzed. The results between low to moderate myopia and high myopia were compared up to 12 months. Results: Mean pre-operative Spherical Equivalent (SE) was -5.15±2.41 Diopters (D) (range -0.50 to -11.50 D) and -0.13±0.28 D, -0.13±0.27 D, -0.13±0.28 D and -0.14±0.30 D at 1, 3, 6, and 12 months, post-operatively. At 12 months, the propor¬tion of eyes achieving UDVA ≥ 20/20 was 90.0% and ≥20/40 was 98.8%. The proportion of eyes achieving post-operative mean SE ±0.5 D, and ±1 D was 91.3%, and 98.5%. No eyes lost more than two lines of BDVA. The low to moderate myopic group had a statistically significant better UDVA at one (p=0.017) and three months (p=0.014) but no difference at six (p=0.061) and 12 months (p=0.091). The mean post-operative SE was better in low to moderate myopic group at every follow-up visit (p=0.001, 0.007, <0.001 and <0.001). Conclusion: One-year clinical results of LASIK with the FS200 femtosecond laser and EX500 excimer laser showed high efficacy, predictability, stability and safety. PMID:29872485

[Study on the change of optical zone after femtosecond laser assisted laser in situ keratomileusis].

PubMed

Li, H; Chen, M; Tian, L; Li, D W; Peng, Y S; Zhang, F F

2018-01-11

Objective: To explore the change of optical zone after femtosecond laser assisted laser in sitn keratomileusis(FS-LASIK) so as to provide the reference for measurement and design of clinical optical zone. Methods: This retrospective case series study covers 41 eyes of 24 patients (7 males and 17 females, aged from 18 to 42 years old) with myopia and myopic astigmatism who have received FS-LASIK surgery at Corneal Refractive Department of Qingdao Eye Hospital and completed over 6 months of clinical follow-up. Pentacam system (with the application of 6 corneal topographic map modes including: the pure axial curvature topographic map, the pure tangential curvature topographic map, the axial curvature difference topographic map, the tangential curvature difference topographic map, the postoperative front elevation map and the corneal thickness difference topographic map), combined with transparent concentric software (a system independently developed by Qingdao Eye Hospital) was used to measure the optical zone at 1, 3 and 6 months postoperatively, the optical zone diameters measurement results among different follow-up times in group were analyzed with the repeated measures analysis of variance, and the actual measured values and the theoretical design values of the optical zone were analyzed with independent-samples t-testing. Spearman correlation coefficient ( r(s) ) have been applied to evaluate the relationship between postoperative optical zone measurement values and the potential influencing factors. Results: The optical zone diameters measured by pure axial curvature topographic map at 1, 3 and 6 months after FS-LASIK showed (6.55±0.50)mm, (6.50±0.53)mm and (6.48±0.53)mm respectively. The differences between values are of no statistical significance ( F= 1.60, P= 0.21), the optical zone diameter measured by pure tangential curvature topographic map at 1, 3 and 6 months after FS-LASIK showed (5.44±0.46)mm, (5.46±0.52)mm and (5.44±0.50)mm respectively, the

Comparison of DLK incidence after laser in situ keratomileusis associated with two femtosecond lasers: Femto LDV and IntraLase FS60

PubMed Central

Tomita, Minoru; Sotoyama, Yuko; Yukawa, Satoshi; Nakamura, Tadayuki

2013-01-01

Purpose To compare the incidence of diffuse lamellar keratitis (DLK) after laser in situ keratomileusis (LASIK) with flap creation using the Femto LDV and IntraLase™ FS60 femtosecond lasers.0 Methods A total of 818 consecutive myopic eyes had LASIK performed using either Femto LDV or IntraLase FS60 for flap creation. The same excimer laser, the Allegretto Wave® Eye-Q Laser, was used for correcting refractive errors for all patients. In the preoperative examination, uncorrected distance visual acuity, corrected distance visual acuity, and manifest refraction spherical equivalent were measured. At the postop examination, the same examinations were performed along with a slit-lamp biomicroscopic examination, and patients with DLK were classified into stages. For the statistical analysis of the DLK occurrence rate and the visual and refractive outcomes, the Mann-Whitney’s U-test was used. Results In the Femto LDV group with 514 eyes, 42 (8.17%) had DLK. In the IntraLase FS60 group with 304 eyes, 114 (37.5%) had DLK. There was a statistically significant difference in the DLK incidence rate between these groups (P < 0.0001). Both groups had excellent visual and refractive outcomes. Although low levels of DLK were observed for both groups, they did not affect visual acuity. Conclusion While there were significantly fewer incidences of low level DLK when using Femto LDV, neither femtosecond laser induced high levels of DLK, and any postoperative DLK cleared up within 1 week. Therefore, both lasers provide excellent results, with no clinical differences, and both excel at flap creation for LASIK. PMID:23874077

Comparison of 2 femtosecond lasers for flap creation in myopic laser in situ keratomileusis: one-year results.

PubMed

Yu, Charles Q; Manche, Edward E

2015-04-01

To compare laser in situ keratomileusis (LASIK) outcomes between 2 femtosecond lasers for flap creation in the treatment of myopia up to 1 year. University eye clinic. Prospective randomized eye-to-eye study. Consecutive myopic patients were treated with wavefront-guided LASIK. One eye had a flap created by the Intralase FS 60 kHz femtosecond laser, and the fellow eye was treated with the Intralase iFS 150 kHz femtosecond laser. Eyes were randomized according to ocular dominance. Evaluations included measurement of uncorrected distance visual acuity (UDVA), corrected distance visual acuity, contrast sensitivity and wavefront aberrometry. The study enrolled 122 eyes of 61 patients. The mean preoperative spherical equivalent refraction was -4.62 diopters (D) ± 2.32 (SD) and -4.66 ± 2.30 D in the 150 kHz group and 60 kHz group, respectively. Patients preferred the 150 kHz laser to the 60 kHz laser intraoperatively (52.5% versus 26.2%) (P = .005). One week postoperatively, UDVA was 20/16 or better in 85.2% in the 150 kHz group and 70.5% in the 60 kHz group; the difference was statistically significant (P < .05). At 12 months, there were no significant differences in refractive outcomes or higher-order aberrations between the 2 groups. Flap creation with the 150 kHz system and the 60 kHz system resulted in excellent LASIK outcomes. Intraoperatively, patients preferred the 150 kHz system, which yielded better UDVA in the early postoperative period. There were no significant differences at 1 year between the 2 laser systems. Proprietary or commercial disclosures are listed after the references. Copyright © 2015 ASCRS and ESCRS. Published by Elsevier Inc. All rights reserved.

Confocal microscopy of corneal stroma and endothelium after LASIK and PRK.

PubMed

Amoozadeh, Javad; Aliakbari, Soheil; Behesht-Nejad, Amir-Houshang; Seyedian, Mohammad-Amin; Rezvan, Bijan; Hashemi, Hassan

2009-10-01

To compare with confocal microscopy the changes in stromal keratocyte density and endothelial cell count due to photorefractive keratectomy (PRK) and LASIK. In this prospective study, 32 eyes (16 myopic patients) were examined with the NIDEK Confoscan 3 confocal microscope before and 6 months after PRK and LASIK. The preoperative mean myopia was -2.85+/-0.99 diopters (D) (range: -1.00 to -4.00 D) in 24 eyes that underwent PRK and -2.94+/-0.96 D (range: -2.00 to -4.25 D) in 8 eyes that underwent LASIK. Keratocyte density in the anterior and posterior stroma and the endothelial cell count were measured. Statistically significant changes were assessed using the t test. P<.05 was considered statistically significant. Preoperative hexagonal cell percentage in the LASIK group was 52.17+/-11.43 and 51.33+/-10.98 in the PRK group. Postoperatively, the percentages were 52.96+/-7.55 and 53.34+/-10.2, respectively. Six months postoperatively, keratocyte density changed by 367.12+/-103.35 cells/mm(2) (34.7% reduction) in the anterior stroma (P<.05) and 9.25+/-28.28 cells/mm(2) (1.31% reduction) in the posterior stroma (P>.05) for the LASIK group. In the PRK group, these values were 319.71+/-83.45 cells/mm(2) (31.13% reduction) in the anterior stroma (P<.05) and 0.17+/-38.97 cells/mm(2) (0.02% reduction) in the posterior stroma (P>.05). The changes in keratocyte densities were not statistically significant between groups (P>.05). The mean number of keratocytes decreased by 37.2% in the retroablation zone of the LASIK group (P<.05). No changes were noted in endothelial cell counts. A significant decrease occurred in the number of stromal keratocytes in the anterior stroma. Despite differences in surgery, the change in keratocyte density and endothelial cell counts were similar between LASIK and PRK groups (P>.05). Copyright 2009, SLACK Incorporated.

Predictive factor analysis for successful performance of iris recognition-assisted dynamic rotational eye tracking during laser in situ keratomileusis.

PubMed

Prakash, Gaurav; Ashok Kumar, Dhivya; Agarwal, Amar; Jacob, Soosan; Sarvanan, Yoga; Agarwal, Athiya

2010-02-01

To analyze the predictive factors associated with success of iris recognition and dynamic rotational eye tracking on a laser in situ keratomileusis (LASIK) platform with active assessment and correction of intraoperative cyclotorsion. Interventional case series. Two hundred seventy-five eyes of 142 consecutive candidates underwent LASIK with attempted iris recognition and dynamic rotational tracking on the Technolas 217z100 platform (Techolas Perfect Vision, St Louis, Missouri, USA) at a tertiary care ophthalmic hospital. The main outcome measures were age, gender, flap creation method (femtosecond, microkeratome, epi-LASIK), success of static rotational tracking, ablation algorithm, pulses, and depth; preablation and intraablation rotational activity were analyzed and evaluated using regression models. Preablation static iris recognition was successful in 247 eyes, without difference in flap creation methods (P = .6). Age (partial correlation, -0.16; P = .014), amount of pulses (partial correlation, 0.39; P = 1.6 x 10(-8)), and gender (P = .02) were significant predictive factors for the amount of intraoperative cyclodeviation. Tracking difficulties leading to linking the ablation with a new intraoperatively acquired iris image were more with femtosecond-assisted flaps (P = 2.8 x 10(-7)) and the amount of intraoperative cyclotorsion (P = .02). However, the number of cases having nonresolvable failure of intraoperative rotational tracking was similar in the 3 flap creation methods (P = .22). Intraoperative cyclotorsional activity depends on the age, gender, and duration of ablation (pulses delivered). Femtosecond flaps do not seem to have a disadvantage over microkeratome flaps as far as iris recognition and success of intraoperative dynamic rotational tracking is concerned. Copyright (c) 2010 Elsevier Inc. All rights reserved.

Contralateral comparison of wavefront-guided LASIK surgery with iris recognition versus without iris recognition using the MEL80 Excimer laser system.

PubMed

Wu, Fang; Yang, Yabo; Dougherty, Paul J

2009-05-01

To compare outcomes in wavefront-guided LASIK performed with iris recognition software versus without iris recognition software in different eyes of the same patient. A randomised, prospective study of 104 myopic eyes of 52 patients undergoing LASIK surgery with the MEL80 excimer laser system was performed. Iris recognition software was used in one eye of each patient (study group) and not used in the other eye (control group). Higher order aberrations (HOAs), contrast sensitivity, uncorrected vision (UCV), visual acuity (VA) and corneal topography were measured and recorded pre-operatively and at one month and three months post-operatively for each eye. The mean post-operative sphere and cylinder between groups was similar, however the post-operative angles of error (AE) by refraction were significantly smaller in the study group compared to the control group both in arithmetic and absolute means (p = 0.03, p = 0.01). The mean logMAR UCV was significantly better in the study group than in the control group at one month (p = 0.01). The mean logMAR VA was significantly better in the study group than in control group at both one and three months (p = 0.01, p = 0.03). In addition, mean trefoil, total third-order aberration, total fourth-order aberration and the total scotopic root-mean-square (RMS) HOAs were significantly less in the study group than those in the control group at the third (p = 0.01, p = 0.05, p = 0.04, p = 0.02). By three months, the contrast sensitivity had recovered in both groups but the study group performed better at 2.6, 4.2 and 6.6 cpd (cycles per degree) than the control group (p = 0.01, p < 0.01, p = 0.01). LASIK performed with iris recognition results in better VA, lower mean higher-order aberrations, lower refractive post-operative angles of error and better contrast sensitivity at three months post-operatively than LASIK performed without iris recognition.

Intraocular straylight and contrast sensitivity after contralateral wavefront-guided LASIK and wavefront-guided PRK for myopia.

PubMed

Barreto, Jackson; Barboni, Mirella T S; Feitosa-Santana, Claudia; Sato, João R; Bechara, Samir J; Ventura, Dora F; Alves, Milton Ruiz

2010-08-01

To compare intraocular straylight measurements and contrast sensitivity after wavefront-guided LASIK (WFG LASIK) in one eye and wavefront-guided photorefractive keratectomy (WFG PRK) in the fellow eye for myopia and myopic astigmatism correction. A prospective, randomized study of 22 eyes of 11 patients who underwent simultaneous WFG LASIK and WFG PRK (contralateral eye). Both groups were treated with the NIDEK Advanced Vision Excimer Laser System, and a microkeratome was used for flap creation in the WFG LASIK group. High and low contrast visual acuity, wavefront analysis, contrast sensitivity, and retinal straylight measurements were performed preoperatively and at 3, 6, and 12 months postoperatively. A third-generation straylight meter, C-Quant (Oculus Optikgeräte GmbH), was used for measuring intraocular straylight. Twelve months postoperatively, mean uncorrected distance visual acuity was -0.06 +/- 0.07 logMAR in the WFG LASIK group and -0.10 +/- 0.10 logMAR in the WFG PRK group. Mean preoperative intraocular straylight was 0.94 +/- 0.12 logs for the WFG LASIK group and 0.96 +/- 0.11 logs for the WFG PRK group. After 12 months, the mean straylight value was 1.01 +/- 0.1 log s for the WFG LASIK group and 0.97 +/- 0.12 log s for the WFG PRK group. No difference was found between techniques after 12 months (P = .306). No significant difference in photopic and mesopic contrast sensitivity between groups was noted. Intraocular straylight showed no statistically significant increase 1 year after WFG LASIK and WFG PRK. Higher order aberrations increased significantly after surgery for both groups. Nevertheless, WFG LASIK and WFG PRK yielded excellent visual acuity and contrast sensitivity performance without significant differences between techniques.

Non-Invasive Evaluation of Corneal Abnormalities Using Static and Dynamic Light Scattering

NASA Technical Reports Server (NTRS)

Ansari, Rafat R.; Misra, Anup K.; Leung, Alfred B.; King, James F.; Datiles, Manuel B., III

2002-01-01

A preliminary study of corneal abnormalities in intact bovine eyes is presented. Twenty-one eyes were treated with chemicals, cotton swabs, and radial and photo-refractive surgeries. Dynamic and static light scattering was performed as a function of the penetration depth into the corneal tissue. Topographical maps of corneal refractive power from untreated and treated corneas were also obtained using videokeratoscopy and results compared. The ultimate aim is to develop the technique of dynamic light scattering (DLS) for clinical applications in early evaluation of corneal complications after laser-assisted in situ keratomileusis (LASIK) surgeries and other corneal abnormalities.

Noninvasive evaluation of corneal abnormalities using static and dynamic light scattering

NASA Astrophysics Data System (ADS)

Ansari, Rafat R.; Misra, Anup K.; Leung, Alfred B.; King, James F.; Datiles, Manuel B., III

2002-06-01

A preliminary study of corneal abnormalities in intact bovine eyes is presented. Twenty-one eyes were treated with chemicals, cotton swabs, and radial and photo-refractive surgeries. Dynamic and static light scattering was performed as a function of the penetration depth into the corneal tissue. Topographical maps of corneal refractive power from untreated and treated corneas were also obtained using videokeratoscopy and results compared. The ultimate aim is to develop the technique of dynamic light scattering (DLS) for clinical applications in early evaluation of corneal complications after laser-assisted in situ keratomileusis (LASIK) surgeries and other corneal abnormalities.

Interface fluid syndrome in human eye bank corneas after LASIK: causes and pathogenesis.

PubMed

Dawson, Daniel G; Schmack, Ingo; Holley, Glenn P; Waring, George O; Grossniklaus, Hans E; Edelhauser, Henry F

2007-10-01

To evaluate the effects of corneal edema on human donor corneas that had previous LASIK using a laboratory model with histologic and ultrastructural correlations. Experimental study. Thirty human eye bank corneas from 15 donors (mean age +/- standard deviation, 49.9+/-8.9 years) who had had previous LASIK surgery (2-8 years before death). The corneas were mounted in an artificial anterior chamber and the corneal endothelium was perfused for up to 5.0 hours with 0.9% saline solution (endothelial cell damage group) or BSS Plus at a pressure of 15 mmHg (control group), or BSS Plus at a pressure of 55 mmHg (high-pressure group). The corneas were evaluated by confocal and specular microscopy before, during, and at the end of the experimental period. Subsequently, the specimens were evaluated by light and electron microscopy. Corneal thickness, reflectivity, histology, and ultrastructure. Endothelial cell damage resulted in an increased (141.5+/-38.8 microm) total corneal thickness relative to controls (52.3+/-33.7 microm), whereas high pressure resulted in a decreased thickness (24.8+/-14.1 microm) relative to controls. This ultimately was due to swelling of the LASIK interface in both groups and swelling of the residual stromal bed (RSB) in the endothelial cell damage group or compression of the RSB and, possibly, the flap in the high-pressure group. A significant increase in corneal reflectivity at the LASIK interface occurred in both groups, primarily due to varying degrees of fluid accumulation and associated hydropic keratocyte degeneration, as well as increased corneal reflectivity in the RSB only in the endothelial cell damage group. After LASIK surgery, edematous corneas preferentially hydrate and swell in the paracentral and central interface wound, commonly resulting in a hazy corneal appearance primarily due to keratocyte hydropic degeneration. More severe corneal edema is characterized by the formation of an optically empty space corresponding to an

Changes in ocular biomechanics after femtosecond laser creation of a laser in situ keratomileusis flap.

PubMed

Leccisotti, Antonio; Fields, Stefania V; Moore, Johnny; Shah, Sunil; Moore, Tara C B

2016-01-01

To evaluate ocular biomechanical parameters with the Corvis ST, a noncontact tonometer combined with an ultra-high-speed Scheimpflug camera, before and after creation of a femtosecond laser-created laser in situ keratomileusis (LASIK) flap. Private practice, Siena, Italy. Prospective consecutive study. Right eyes of patients having LASIK were assessed with the dynamic Scheimpflug camera before and after femtosecond laser (LDV Z4) flap creation but before mechanical flap lifting. Twenty-eight eyes of 28 patients were evaluated. Before flap creation, the mean values on the dynamic Scheimpflug camera were intraocular pressure (IOP), 15.04 mm Hg ± 3.99 (SD); central pachymetry, 550.8 ± 101.0 μm; applanation 1 length, 1.721 ± 0.134 mm; applanation 2 length, 1.674 ± 0.287 mm; applanation 1 velocity, 0.126 ± 0.031 m/s; and deflection amplitude, 1.039 ± 0.141 mm. After flap creation, the mean values were IOP, 16.10 ± 3.11 mm Hg (95% confidence interval [CI], 0.44-1.78; P < .05); central pachymetry, 561.8 ± 35.9 μm (95% CI, -28.9 to 50.9; P = .21); applanation 1 length, 1.789 ± 0.1492 mm (95% CI, 0.003-0.134; P < .05); applanation 2 length, 1.759 ± 0.259 mm (95% CI, -0.005 to 0.173; P = .08); applanation 1 velocity, 0.136 ± 0.022 m/s (95% CI, 0.001-0.017; P < .05); and deflection amplitude, 1.029 ± 0.151 mm (95% CI: -0.043 to 0.025; P = .34). The dynamic Scheimpflug camera showed changes in biomechanical properties after femtosecond creation of a LASIK flap as indicated by an increased applanation 1 length and applanation 1 velocity. No author has a financial or proprietary interest in any material or method mentioned. Copyright © 2016 ASCRS and ESCRS. Published by Elsevier Inc. All rights reserved.

Meta-analysis of Pentacam vs. ultrasound pachymetry in central corneal thickness measurement in normal, post-LASIK or PRK, and keratoconic or keratoconus-suspect eyes.

PubMed

Wu, Wenjing; Wang, Yan; Xu, Lulu

2014-01-01

The aim of this meta-analysis is to evaluate the central corneal thickness (CCT) measurement differences between Pentacam (Oculus Inc., Germany) and Ultrasound Pachymetry (USP) in normal (unoperated eyes , myopic and astigmatic eyes without corneal disease or topographic irregularity), after laser in situ keratomileusis (LASIK) or photorefractive keratectomy (PRK), and keratoconic or keratoconus suspected eyes. We assess whether Pentacam and USP have similar CCT differences in normal, thinner corneas after LASIK or PRK procedures, and kerotoconic or keratoconus suspected eyes. Data sources, including PubMed, Medline, EMBASE, and Cochrane Central Registry of Controlled Trials on the Cochrane Library, were searched to find the relevant studies. Primary outcome measures were CCT measurement between Pentacam and USP. Three groups of eyes were analyzed: normal; LASIK or PRK eyes; and keratoconus suspected or keratoconic eyes. Nineteen studies describing 1,908 eyes were enrolled in the normal group. Pentacam results were 1.47 μm ,95 % confidence interval (CI) -2.32 to 5.27, higher than USP without statistically significant difference (P = 0.45). Nine studies with total 539 eyes were included in the corneas after LASIK or PRK. The mean difference in the CCT measurement with Pentacam and ultrasound pachymetry was 1.03 μm, with the 95 % CI -3.36 to 5.42, there was no statistically difference (P = 0.64). Four studies with a total of 185 eyes were included in the keratoconic eyes or keratoconus-suspect group, however,the mean difference was -6.33 μm (95 % CI -9.17 to-3.49), which was statistically different between Pentacam and ultrasound pachymetry in the CCT measurement (P < 0.0001). Pentacam offers similar CCT results to ultrasound pachymetry in normal eyes, thinner corneas after LASIK or PRK procedures. However, in keratoconic or keratoconus-suspect eyes, Pentacam slightly underestimates the central corneal thickness than does ultrasound pachymetry

Active eye-tracking improves LASIK results.

PubMed

Lee, Yuan-Chieh

2007-06-01

To study the advantage of active eye-tracking for photorefractive surgery. In a prospective, double-masked study, LASIK for myopia and myopic astigmatism was performed in 50 patients using the ALLEGRETTO WAVE version 1007. All patients received LASIK with full comprehension of the importance of fixation during the procedure. All surgical procedures were performed by a single surgeon. The eye-tracker was turned off in one group (n = 25) and kept on in another group (n = 25). Preoperatively and 3 months postoperatively, patients underwent a standard ophthalmic examination, which included comeal topography. In the patients treated with the eye-tracker off, all had uncorrected visual acuity (UCVA) of > or = 20/40 and 64% had > or = 20/20. Compared with the patients treated with the eye-tracker on, they had higher residual cylindrical astigmatism (P < .05). Those treated with the eye-tracker on achieved better UCVA and best spectacle-corrected visual acuity (P < .05). Spherical error and potential visual acuity (TMS-II) were not significantly different between the groups. The flying-spot system can achieve a fair result without active eye-tracking, but active eye-tracking helps improve the visual outcome and reduces postoperative cylindrical astigmatism.

Oral Gabapentin for Photorefractive Keratectomy Pain

DTIC Science & Technology

2011-02-01

keratomileusis ( LASIK ) is the predomi- nant procedure of choice for most patients and surgeons, photorefractive keratectomy (PRK) remains a viable...thus have an increased risk for LASIK flap dislocation.2,3 Although slower visual recovery, prolonged use of topical steroidal agents, and...postoperative corneal haze are considered drawbacks to PRK compared with LASIK ,4,5 the primary disadvantage of PRK is postoperative pain. Topical and oral

Accuracy of refractive outcomes in myopic and hyperopic laser in situ keratomileusis: Manifest versus aberrometric refraction.

PubMed

Reinstein, Dan Z; Morral, Merce; Gobbe, Marine; Archer, Timothy J

2012-11-01

To compare the achieved refractive accuracy of laser in situ keratomileusis (LASIK) performed based on manifest refraction with the predicted accuracy that would have been achieved using WASCA aberrometric refraction with and without Seidel correction factor for sphere. London Vision Clinic, London, United Kingdom. Comparative case series. Myopic eyes and hyperopic eyes had LASIK based on manifest refraction. Two aberrometric refractions were obtained preoperatively: Seidel, which includes spherical aberration in the sphere calculation, and non-Seidel. Bland-Altman plots were used to show the agreement between aberrometric and manifest refractions. Predicted LASIK outcomes had aberrometric refraction been used were modeled by shifting the postoperative manifest refraction by the vector difference between the preoperative manifest and aberrometric refractions. This study included 869 myopic eyes and 413 hyperopic eyes. The mean differences (manifest minus aberrometric) in spherical equivalent were +0.03 diopters (D) ± 0.48 (SD) (Seidel aberrometric) and +0.45 ± 0.42 D (non-Seidel aberrometric) for myopia and -0.20 ± 0.39 D and +0.39 ± 0.34 D, respectively, for hyperopia. The mean differences in cylinder magnitude were -0.10 ± 0.27 D and 0.00 ± 0.25 D, respectively. The percentage of eyes within ±0.50 D of the attempted correction was 81% (manifest), 70% (Seidel), and 67% (non-Seidel) for myopia and 71% (manifest), 61% (Seidel), and 64% (non-Seidel) for hyperopia. The achieved refractive accuracy by manifest refraction was better than the predicted accuracy had Seidel or non-Seidel aberrometric refractions been used for surgical planning. Using the Seidel method improved the accuracy in myopic eyes but not in hyperopic eyes. Dr. Reinstein is a consultant to Carl Zeiss Meditec AG and has a proprietary interest in the Artemis technology (Arcscan Inc., Morrison, Colorado, USA) through patents administered by the Cornell Center for Technology Enterprise and

Topical cyclosporine a treatment in corneal refractive surgery and patients with dry eye.

PubMed

Torricelli, Andre A M; Santhiago, Marcony R; Wilson, Steven E

2014-08-01

To evaluate preoperative and postoperative dry eye and the effect of cyclosporine A treatment in patients screened for corneal refractive surgery and treated with photorefractive keratectomy (PRK) or LASIK. A consecutive case series of 1,056 patients screened for corneal refractive surgery from 2007 to 2012 was retrospectively analyzed. The level of preoperative and postoperative dry eye and the responsiveness to topical cyclosporine A treatment were assessed. One eye of each patient was randomly selected. A total of 642 eyes progressed to surgery: 524 (81.6%) and 118 (18.4%) underwent LASIK and PRK, respectively. Of 81 (7.7%) diagnosed as having dry eye, 55 were deemed potential candidates and optimized for refractive surgery. Thirty-seven patients with moderate dry eye were treated with topical cyclosporine A prior to surgery (mean duration: 3.2 ± 2.1 months; range: 1 to 12 months). After cyclosporine A treatment, 28 (75.7%) eyes underwent LASIK, 4 (10.8%) eyes underwent PRK, and 5 (13.5%) eyes were not operated on due to failed treatment of dry eye. Postoperative refractive surgery-induced neurotrophic epitheliopathy (LINE in LASIK) was noted in 132 (27.3%) and 12 (11.1%) eyes that underwent LASIK and PRK, respectively. Topical cyclosporine A was prescribed in 79 LASIK-induced and 3 PRK-induced dry eyes. After 12 months or more of cyclosporine A treatment, 5 (6.1%) eyes continued to have dry eye symptoms or signs. Topical cyclosporine A treatment is effective therapy for optimizing patients for refractive surgery and treatment of new onset or worsened dry eye after surgery. Copyright 2014, SLACK Incorporated.

[Safety of the automated microkeratome for Sub-Bowman's Keratomileusis on the flat cornea].

PubMed

Falcon, C; Norero Martinez, M

2016-02-01

Use of the One Use-Plus SBK (Sub-Bowman's Keratomileusis) automated microkeratome (Moria, Antony, France) has been shown to be safe, predictable and comfortable for the creation of thin corneal flaps with a smooth and regular stromal bed. To evaluate the use of the Moria One Use-Plus SBK (Moria, Antony, France) automated microkeratome on corneas with 180°-keratometry under 40 diopters (D). We retrospectively studied cases that underwent SBK whose 180°-keratometry was under 40 D. We separated the cases between 39 and 40 D and those less than 39 D. The preoperative data, the procedure and the postoperative outcomes were analyzed. The Moria One Use-Plus SBK microkeratome with the 90-micron head was used for all cases. Among the 2883 eyes that underwent SBK LASIK over the past six years, 80 eyes (2.77%) had a preoperative topographical 180°-keratometry of less than 40 D: 63 eyes (2.19%) between 39 and 40 D and 17 eyes (0.59%) between 38 and 39 D (38.13-38.97 D). The spherical equivalent was between -3.50 D (-2.25 sph -2.50 cyl. at 175°) and+6.00 D (+5.50 sph +1.00 cyl. at 85°). Fifty-eight eyes (72.5%) had hyperopia and/or hyperopic astigmatism; 18 eyes (22.5%) had mixed astigmatism; and 4 eyes (5%) had myopia and/or myopic astigmatism. Twenty-six eyes (32%) had a history of strabismus. Thirteen patients (27.66%) had a history of amblyopia. The "-1" ring was used in all cases, with a 7.5 stop (14%) or 8 stop (86%). The procedure went uneventfully in all cases with a stable vacuum between 117 and 123 mm Hg. The nasal hinge and the stromal bed were normal in size in all cases and sufficient to perform the photoablation laser safely with an optical zone between 6.00 and 7.00 millimeters. There were no intraoperative nor immediate postoperative complications: free cap 0%; incomplete flap 0%; button hole 0%; epithelial erosion 0%; bleeding 0%; irregular stromal bed 0%. Postoperative complications: flap displacement 0%; punctate keratitis: 8%; LASIK retreatments: 12

Night firing range performance following photorefractive keratectomy and laser in situ keratomileusis.

PubMed

Bower, Kraig S; Burka, Jenna M; Subramanian, Prem S; Stutzman, Richard D; Mines, Michael J; Rabin, Jeff C

2006-06-01

To investigate the effect of laser refractive surgery on night weapons firing. Firing range performance was measured at baseline and postoperatively following photorefractive keratectomy and laser in situ keratomileusis. Subjects fired the M-16A2 rifle with night vision goggles (NVG) at starlight, and with iron sight (simulated dusk). Scores, before and after surgery, were compared for both conditions. No subject was able to acquire the target using iron sight without correction before surgery. After surgery, the scores without correction (95.9 +/- 4.7) matched the preoperative scores with correction (94.3 +/- 4.0; p = 0.324). Uncorrected NVG scores after surgery (96.4 +/- 3.1) exceeded the corrected scores before surgery (91.4 +/- 10.2), but this trend was not statistically significant (p = 0.063). Night weapon firing with both the iron sight and the NVG sight improved after surgery. This study supports the operational benefits of refractive surgery in the military.

Surgical and healing changes to ocular aberrations following refractive surgery

NASA Astrophysics Data System (ADS)

Straub, Jochen; Schwiegerling, Jim

2003-07-01

Purpose: To measure ocular aberrations before and at several time periods after LASIK surgery to determine the change to the aberration structure of the eye. Methods: A Shack-Hartmann wavefront sensor was used to measure 88 LASIK patients pre-operatively and at 1 week and 12 months following surgery. Reconstructed wavefront errors are compared to look at induced differences. Manifest refraction was measured at 1 week, 1 month, 3 months, 6 months and 12 months following surgery. Sphere, cylinder, spherical aberration, and pupil diameter are analyzed. Results: A dramatic elevation in spherical aberration is seen following surgery. This elevation appears almost immediately and remains for the duration of the study. A temporary increase in pupil size is seen following surgery. Conclusions: LASIK surgery dramatically reduces defocus and astigmatism in the eye, but simultaneously increases spherical aberration levels. This increase occurs at the time of surgery and is not an effect of the healing response.

Opaque bubble layer incidence in Femtosecond laser-assisted LASIK: comparison among different flap design parameters.

PubMed

Mastropasqua, Leonardo; Calienno, Roberta; Lanzini, Manuela; Salgari, Niccolò; De Vecchi, Sergio; Mastropasqua, Rodolfo; Nubile, Mario

2017-06-01

The purpose of this study was to evaluate the incidence of opaque bubble layer (OBL) in femtosecond laser-assisted in situ keratomileusis (LASIK) flaps created with the support of Visumax Carl Zeiss femtosecond laser, planned with different flap diameters (7.90, 8.0, and 8.20 mm) and the same laser energy and power settings. Incidence of intraoperative OBL in flaps of consecutive 108 patients (216 eyes) subjected to bilateral femtosecond-assisted LASIK was considered. Flap creation was performed with the same laser design parameters (spot distance and energy offset) and different presetting diameters of 7.90 mm (72 eyes, group 1), 8 mm (72 eyes, group 2), and 8.20 mm (72 eyes, group 3). The incidence of OBL was considered and its extension was reported measuring involvement of different four corneal flap quadrants in which was theoretically divided the entire flap area; based on these data, OBL presence was classified as none (no evidence of OBL), minimal (minimal presence in not more that one quadrants corneal flap), mild (OBL presence in almost two or three quadrants without tendency to invade central cornea), and moderate (OBL presence in almost three quadrants with tendency to invade central cornea). In group 1, the incidence of OBL was of 23.6 % (17 eyes) with a mild/moderate presence; in group 2, incidence was 20.8 % (15 eyes) with mild presence. Group 3 presented a reduced OBL incidence (4.1 %, 3 eye) with a minimal presence. No statistically significant difference was found between group 1 and 2 (p = 0.8414).We found statistically significant differences between group 1 and group 3 (p = 0.0012) and between groups 2 and 3 (p = 0.0044). A significant reduction and extension of OBL incidence were evident when LASIK flap settings diameter was increased, and flap edge was closer to the contact glass border; this is probably consequent to a more effective gas dispersion outside of corneal flap.

Comparison of 5468 retreatments after laser in situ keratomileusis by lifting the flap or performing photorefractive keratectomy on the flap.

PubMed

Ortega-Usobiaga, J; Llovet-Osuna, F; Katz, T; Djodeyre, M R; Druchkiv, V; Bilbao-Calabuig, R; Baviera, J

2018-02-01

To assess visual outcomes of retreatment after laser in situ keratomileusis (LASIK) by lifting the flap or performing photorefractive keratectomy (PRK) on the flap, as well as to establish whether there was an increased risk of epithelial ingrowth (EIG) when LASIK and lifting of the flap are separated by a long time interval and to determine the incidence of corneal haze after PRK. Retrospective study of 4077 patients (5468 eyes) who underwent LASIK and subsequent retreatment were reviewed in order to study their visual results and identify cases of EIG and corneal haze. Enhancements included 5196 eyes from 3876 patients that were retreated by lifting the flap, and 272 eyes from 201 patients that were retreated by PRK on the flap. No statistically significant differences were found between the retreatments in terms of predictability, efficacy, and safety. A total of 704 cases of EIG were found after lifting the flap, for which surgical cleansing was necessary in 70. Surgical cleansing decreased the efficacy index when compared with patients with EIG who did not need cleansing (P=.01). Differences in terms of safety and predictability were not statistically significant. The incidence of corneal haze after ablation of the surface of the previous flap was 14.34%, although none of these cases were clinically relevant. Visual outcomes were similar between patients who were retreated by lifting the flap and those who underwent PRK. The incidence of EIG when the flap was lifted was 13.55%. The incidence of EIG increases with the time elapsed between the primary procedure and retreatment. Copyright © 2017 Sociedad Española de Oftalmología. Publicado por Elsevier España, S.L.U. All rights reserved.

Comparison of laser in situ ketatomileusis and photorefractive keratectomy for myopia using a mixed-effects model

PubMed Central

Mori, Yosai; Miyata, Kazunori; Ono, Takashi; Yagi, Yusuke; Kamiya, Kazutaka; Amano, Shiro

2017-01-01

Purpose To compare the results of laser in situ keratomileusis (LASIK) and photorefractive keratectomy (PRK) for myopia using a mixed-effects model. Methods This comparative retrospective study was conducted in 1,127 eyes of 579 patients after LASIK and 270 eyes of 144 patients after PRK who had two or more postoperative follow-ups after 3 months. Uncorrected visual acuity (UCVA), best spectacle-corrected visual acuity (BSCVA), manifest refractive spherical equivalent (MRSE), percentage of eyes within ± 0.5 diopters (D) and ± 1.0 D of targeted refraction, and central corneal thickness were compared between PRK and LASIK groups using a mixed-effects model. Results Compared with the LASIK group, UCVA in the PRK group was significantly worse in the initial year but was significantly better after 4 years. The average BSCVA was not significantly different between the LASIK and PRK groups after 4 years. The average gain of BSCVA in the PRK group was significantly larger than that of the LASIK group after 2 years. MRSE in the LASIK and PRK groups showed a gradual myopic shift until 6 years after surgery. After 6 years, MRSE in the PRK group remained stable whereas MRSE in the LASIK group continued a myopic shift. The percentages of eyes within ± 0.5 D or ± 1.0 D in the LASIK group were significantly higher than those in the PRK group at 3 months but were significantly lower than those in the PRK group at 10 years. Conclusions PRK for myopia shows better efficacy than LASIK for myopia after 4 years. PMID:28362808

Transmittance and scattering during wound healing after refractive surgery

NASA Astrophysics Data System (ADS)

Mar, Santiago; Martinez-Garcia, C.; Blanco, J. T.; Torres, R. M.; Gonzalez, V. R.; Najera, S.; Rodriguez, G.; Merayo, J. M.

2004-10-01

Photorefractive keratectomy (PRK) and laser in situ keratomileusis (LASIK) are frequent techniques performed to correct ametropia. Both methods have been compared in their way of healing but there is not comparison about transmittance and light scattering during this process. Scattering in corneal wound healing is due to three parameters: cellular size and density, and the size of scar. Increase in the scattering angular width implies a decrease the contrast sensitivity. During wound healing keratocytes activation is induced and these cells become into fibroblasts and myofibroblasts. Hens were operated using PRK and LASIK techniques. Animals used in this experiment were euthanized, and immediately their corneas were removed and placed carefully into a cornea camera support. All optical measurements have been done with a scatterometer constructed in our laboratory. Scattering measurements are correlated with the transmittance -- the smaller transmittance is the bigger scattering is. The aim of this work is to provide experimental data of the corneal transparency and scattering, in order to supply data that they allow generate a more complete model of the corneal transparency.

Visual Outcomes, Quality of Vision, and Quality of Life of Diffractive Multifocal Intraocular Lens Implantation after Myopic Laser In Situ Keratomileusis: A Prospective, Observational Case Series

PubMed Central

2017-01-01

Purpose. To report visual performance and quality of life after implantation of a bifocal diffractive multifocal intraocular lens (MIOL) in postmyopic laser in situ keratomileusis (LASIK) patients. Methods. Prospective, observational case series. Patients with prior myopic LASIK who had implantation of Tecnis ZMA00/ZMB00 MIOL (Abbott Medical Optics) at Hong Kong Sanatorium and Hospital were included. Postoperative examinations included monocular and binocular distance, intermediate and near visual acuity (VA), and contrast sensitivity; visual symptoms (0–5); satisfaction (1–5); spectacle independence rate; and quality of life. Results. Twenty-three patients (27 eyes) were included. No intraoperative complications developed. Mean monocular uncorrected VA at distance, intermediate, and near were 0.13 ± 0.15 (standard deviation), 0.22 ± 0.15, and 0.16 ± 0.15, respectively. Corresponding mean values for binocular uncorrected VA were 0.00 ± 0.10, 0.08 ± 0.13, and 0.13 ± 0.10, respectively. No eyes lost >1 line of corrected distance VA. Contrast sensitivity at different spatial frequencies between operated and unoperated eyes did not differ significantly (all P > 0.05). Mean score for halos, night glare, starbursts, and satisfaction were 1.46 ± 1.62, 1.85 ± 1.69, 0.78 ± 1.31, and 3.50 ± 1.02, respectively. Eighteen patients (78%) reported complete spectacle independence. Mean composite score of the quality-of-life questionnaire was 90.31 ± 8.50 out of 100. Conclusions. Implantation of the MIOL after myopic LASIK was safe and achieved good visual performance. PMID:28133543

Visual Outcomes, Quality of Vision, and Quality of Life of Diffractive Multifocal Intraocular Lens Implantation after Myopic Laser In Situ Keratomileusis: A Prospective, Observational Case Series.

PubMed

Chang, John S M; Ng, Jack C M; Chan, Vincent K C; Law, Antony K P

2017-01-01

Purpose . To report visual performance and quality of life after implantation of a bifocal diffractive multifocal intraocular lens (MIOL) in postmyopic laser in situ keratomileusis (LASIK) patients. Methods . Prospective, observational case series. Patients with prior myopic LASIK who had implantation of Tecnis ZMA00/ZMB00 MIOL (Abbott Medical Optics) at Hong Kong Sanatorium and Hospital were included. Postoperative examinations included monocular and binocular distance, intermediate and near visual acuity (VA), and contrast sensitivity; visual symptoms (0-5); satisfaction (1-5); spectacle independence rate; and quality of life. Results . Twenty-three patients (27 eyes) were included. No intraoperative complications developed. Mean monocular uncorrected VA at distance, intermediate, and near were 0.13 ± 0.15 (standard deviation), 0.22 ± 0.15, and 0.16 ± 0.15, respectively. Corresponding mean values for binocular uncorrected VA were 0.00 ± 0.10, 0.08 ± 0.13, and 0.13 ± 0.10, respectively. No eyes lost >1 line of corrected distance VA. Contrast sensitivity at different spatial frequencies between operated and unoperated eyes did not differ significantly (all P > 0.05). Mean score for halos, night glare, starbursts, and satisfaction were 1.46 ± 1.62, 1.85 ± 1.69, 0.78 ± 1.31, and 3.50 ± 1.02, respectively. Eighteen patients (78%) reported complete spectacle independence. Mean composite score of the quality-of-life questionnaire was 90.31 ± 8.50 out of 100. Conclusions . Implantation of the MIOL after myopic LASIK was safe and achieved good visual performance.

Temporal and Spatial Flap Variability in Laser In-Situ Keratomileusis by Optical Coherence Tomography.

PubMed

Dawood, Yousif Farhan; Al Hassany, Usama; Issa, Ammar F

2017-01-01

To study changes in flap thickness made with two different microkeratome heads across different corneal locations using anterior segment optical coherence tomography (OCT). In this prospective, non-randomized, consecutive case series, subjects who had their laser in-situ keratomileusis (LASIK) flaps made using 90 μm (MSU90) or 130 μm (MSU130) disposable M2 microkeratome heads were examined using OCT. The measurements were performed at three locations (central and 2.5 mm to either side) at 1 day, 1 week, and 1 month postoperatively. The central flap thickness was 123 ± 15, 130 ± 14, and 127 ± 13 μm, respectively, at 1 day, 1 week, and 1 month postoperatively in the MSU90 group (41 eyes) and 142 ± 20, 147 ± 19, and 143 ± 15 μm, respectively, in the MSU130 group (47 eyes). At 1 month, peripheral flap thickness was 161 ± 17 and 159 ± 13 μm, respectively, at 2.5 mm to the right and left of corneal center in the MSU90 group. The corresponding figures were 170 ± 14 and 167 ± 13 μm, respectively, in the MSU130 group. There was a statistically significant difference between the two groups at all locations ( P < 0.001). No statistically significant change in flap thickness was detected in either group at any assessment time. There was a partial positive correlation (after controlling for preoperative manifest refractive spherical equivalent) between central flap thickness and preoperative ultrasound central pachymetry ( r = 0.739, P = 0.036) in the MSU90 group but not in the MSU130 group. Using OCT, changes in flap thickness were minimal in the first month after LASIK. Flap thickness correlated strongly with central corneal thickness if a 90 μm head was used.

Predictability of Pilot Performance from Simulated to Real Flight in the UH-60 (Black Hawk) Helicopter

DTIC Science & Technology

2008-02-01

keratectomy ( PRK ) and laser in-situ keratomileusis ( LASIK ) procedures to determine compatibility, safety, and efficacy of these procedures for rated Army...performance data. Table B- 1. Simulator and aircraft mean flight performance. LASIK PRK Simulator Aircraft Simulator Aircraft Pre-op 60.81 (2.65) 56.41...12 7. Aircraft vs . Simulator scatter plot, hover turn maneuvers

[The correlations between corneal sensation, tear meniscus volume, and tear film osmolarity after femtosecond laser-assisted LASIK].

PubMed

Zhang, Luyan; Sun, Xiyu; Yu, Ye; Xiong, Yan; Cui, Yuxin; Wang, Qinmei; Hu, Liang

2016-01-01

To investigate the correlations between corneal sensation, tear meniscus volume, and tear film osmolarity after femtosecond laser-assisted LASIK (FS-LASIK) surgery. In this prospective clinical study, 31 patients undergoing FS-LASIK for myopia were recruited. The upper and lower tear meniscus volumes (UTMV and LTMV) were measured by customized anterior segment optical coherence tomography, tear film osmolarity was measured by a TearLab Osmolarity test device, central corneal sensation was measured by a Cochet-Bonner esthesiometer preoperatively, at 1 week, 1 and 3 months postoperatively. Repeated measures analysis of variance was used to evaluate whether the tear film osmolarity, tear meniscus volume, and corneal sensation were changed after surgery. The correlations between these variables were analyzed by the Pearson correlation analysis. The tear film osmolarity was (310.03 ± 16.48) mOsms/L preoperatively, (323.51 ± 15.92) mOsms/L at 1 week, (319.93 ± 14.27) mOsms/L at 1 month, and (314.97±12.91) mOsms/L at 3 months. The UTMV was (0.42±0.15), (0.25± 0.09), (0.30±0.11), and (0.35±0.09) μL, respectively; the LTMV was (0.60±0.21),(0.37±0.08), (0.44± 0.14), and (0.52±0.17) μL, respectively. The tear film osmolarity was significantly higher at 1 week and 1 month postoperatively compared with the baseline (P=0.001, 0.004), and reduced to the preoperative level at 3 months (P=0.573). The UTMV, LTMV, and corneal sensation values presented significant decreases at all postoperative time points (all P<0.05). The Pearson correlation analysis showed the postoperative UTMV had a weak relationship with corneal sensation at 1 week after surgery (r=0.356,P=0.005). There were significant correlations between the preoperative LTMV and corneal sensation at 1 week, 1 and 3 months (respectively, r=0.422, 0.366, 0.352;P=0.001, 0.004, 0.006). No significant correlations were found between the tear film osmolarity, tear meniscus volume, and corneal sensation after surgery

Refractive lenticule extraction small incision lenticule extraction: A new refractive surgery paradigm

PubMed Central

Ganesh, Sri; Brar, Sheetal; Arra, Raghavender Reddy

2018-01-01

Small incision lenticule extraction (SMILE), a variant of refractive lenticule extraction technology is becoming increasingly popular, as a flapless and minimally invasive form of laser vision correction (LVC) for the treatment of myopia and myopic astigmatism. This review aims at summarizing the principles, surgical technique, and clinical outcomes in terms of visual and refractive results, safety, efficacy, postoperative dry eye, aberrations, and biomechanics of SMILE and its comparison with other conventional techniques of LVC, such as laser in situ keratomileusis (LASIK) and photorefractive keratectomy (PRK). Recent advancements in the laser frequency and energy delivery patterns, instrumentation, and surgical techniques have shown significant improvement in the visual recovery and outcomes after SMILE, compared to the initial results published by Sekundo and Shah et al. Most of the recently published literature on long-term outcomes of SMILE shows excellent stability of the procedure, especially for higher myopia. In terms of the postoperative dry eye, SMILE shows a clear advantage over LASIK as numerous studies have shown significant differences about the Schirmer's, Tear film break up time, corneal sensitivity, and corneal nerve regeneration to be better following SMILE compared to LASIK. There is some evidence that since the Bowman's membrane (BM) and the anterior lamellae remain intact after SMILE, this may be a potential advantage for corneal biomechanics over LASIK and PRK where the BM is either severed or ablated, respectively, however, the data on biomechanics are inconclusive at present. Overall, this procedure has proved to be promising, delivering equivalent, or better visual and refractive results to LASIK and providing clear advantage in terms of being a flapless, minimally invasive procedure with minimal pain and postoperative discomfort thus offering high patient satisfaction. PMID:29283117

Investigation of possible fs-LASIK induced retinal damage

NASA Astrophysics Data System (ADS)

Schumacher, S.; Sander, M.; Stolte, A.; Doepke, C.; Baumgaertner, W.; Lubatschowski, H.

2006-02-01

Rapid development of new laser technologies enabled the application of ultra short lasers in refractive surgery. Focused ultra short laser pulses in near-infrared spectral range can generate a laser induced breakdown (LIB) in the cornea, which will disrupt the tissue. Cutting depth and position can be established by varying the laser focus. The fs-LASIK technique allows both flap and lenticule to be formed by using fs-pulses without the presence of any mechanical impact. During the cutting process not all of the pulse energy is deposited into the cornea; approximately half of the remaining energy propagates through the eye and reaches the retina. Though defocused, the transmitted energy can still induce damage to the retina due to absorption by the retinal pigment epithelium and the transfer of thermal energy to surrounding tissue. The fs-LASIK process was simulated with two laser systems; one continous-wave and one in the fs-regime. For the simulation the exposure time and focusing numerical aperature which defines the retinal spot size were varied. The Damage thresholds of the laser beam exposed eyes were determined in terms of ophthalmoscopic and histopathologic observations.

Optimization of the parameters for intrastromal refractive surgery with ultrashort laser pulses

NASA Astrophysics Data System (ADS)

Heisterkamp, Alexander; Ripken, Tammo; Lubatschowski, Holger; Welling, Herbert; Dommer, Wolfgang; Luetkefels, Elke; Mamom, Thanongsak; Ertmer, Wolfgang

2001-06-01

Focussing femtosecond laser pulses into a transparent media, such as corneal tissue, leads to optical breakdown, generation of a micro-plasma and, thus, a cutting effect inside the tissue. To proof the potential of fs-lasers in refractive surgery, three-dimensional cutting within the corneal stroma was evaluated. With the use of ultrashort laser pulses within the LASIK procedure (laser in situ keratomileusis) possible complications in handling of a mechanical knife, the microkeratome, can be reduced by using the treatment laser as the keratome itself. To study woundhealing effects, animal studies were carried out in rabbit specimen. The surgical outcome was analyzed by means of histological sections, as well as light and scanning electron microscopy. Dependencies on the dispersion caused by focussing optics were evaluated and optimized. Thus, pulse energies well below 1 (mu) J were sufficient to perform the intrastromal cuts. The laser pulses with a duration of 180 fs and energies of 0.5-100 (mu) J were provided by a modelocked frequency doubled erbium fiber-laser with subsequent chirped pulse amplification in a titanium sapphire amplifier at up to 3 kHz.

Two-year results of femtosecond assisted LASIK versus PRK for different severity of astigmatism.

PubMed

Miraftab, Mohammad; Hashemi, Hassan; Asgari, Soheila

2018-03-01

To compare two-year results of femtosecond laser assisted LASIK (femto-LASIK) and photorefractive keratectomy (PRK) in terms of astigmatism correction in patients with less than 2.0 diopters (D) of spherical error and more than 2.0 D of cylinder error. In this retrospective study, data were extracted from 100 patient charts. The two study groups were matched by age, gender, and baseline uncorrected distance visual acuity (UDVA) and refractive astigmatism (RA). Preoperative astigmatism was categorized as mild: 2.00 to <3.00 D, moderate: 3.00 to <4.00 D, and severe: ≥4.00 D. Mean RA in the femto-LASIK and PRK groups was respectively -3.15 ± 0.94 D (-7.00 to -2.00 D) and -3.29 ± 0.95 D (-6.25 to -2.00 D) at baseline ( P  = 0.284), and -0.61 ± 0.40 D and -0.62 ± 0.60 D one year after surgery ( P  = 0.674), but significantly lower in the femto-LASIK group (-0.61 ± 0.39 vs. -0.83 ± 0.56 D, P  = 0.021) at 2 years when the rate of residual astigmatism more than 1.0 D was 6.3% in the femto-LASIK and 19.6% in the PRK group ( P  = 0.046). Mean UDVA in the femto-LASIK group (0.02 ± 0.05 logMAR) was better than the PRK group (0.06 ± 0.10 logMAR) ( P  = 0.025). Mean corrected distance visual acuity (CDVA) was not significantly different between groups (0.01 ± 0.03 vs. 0.01 ± 0.04 logMAR, P  = 0.714). Both groups had 1-4 Snellen lines CDVA improvement. The three subgroups of baseline astigmatism did not differ significantly in terms of residual astigmatism (all P  > 0.05). However, in subgroups with ≥4.00 D cylinder, there was less astigmatic regression at 1 year in the femto-LASIK group (0.28 ± 0.43 D) than the PRK group (0.54 ± 0.68 D) ( P  = 0.007). Our results pointed to better two-year results with femto-LASIK in the treatment of different degrees of astigmatism. UDVA improvement was superior with femto-LASIK, but the two methods did not significantly differ in terms of CDVA improvement.

Preliminary results of tracked laser-assisted in-situ keratomileusis (T-LASIK) for myopia and hyperopia using the autonomous technologies excimer laser system

NASA Astrophysics Data System (ADS)

Maguen, Ezra I.; Nesburn, Anthony B.; Salz, James J.

2000-06-01

A study was undertaken to assess the safety and efficacy of LASIK with the LADARVision laser by Autonomous Technologies, (Orlando, FL). The study included four subsets: Spherical myopia -- up to -11.00D, spherical hyperopia -- up to +6.00D. Both myopic and hyperopic astigmatism could be corrected, up to 6.00D of astigmatism. A total of 105 patients participated. Sixty-six patients were myopic and 39 were hyperopic. The mean (+/- SD) age was 42.8 +/- 9.3 years for myopia and 53.2 +/- 9.9 years for hyperopia. At 3 months postop. Sixty-one myopic eyes were available for evaluation. Uncorrected visual acuity was 20/20 in 70% of eyes and 20/40 in 92.9% of all eyes. The refractive outcome was within +/- 0.50D in 73.8% of eyes and within +/- 1.00D in 96.7 of eyes. Thirty-eight hyperopic eyes were available. Uncorrected visual acuity was 20/20 in 42.1% of eyes and 20/40 in 88% of all eyes. The refractive outcome was within +/- 0.50D in 57.9% of eyes and within +/- 1.00D in 86.8% of eyes. Complications were not sight threatening and were discussed in detail. Lasik with the LADARVision laser appears to be safe and effective.

Laser in situ keratomileusis for -6.00 to -18.00 diopters of myopia and up to -5.00 diopters of astigmatism: 15-year follow-up.

PubMed

Alió, Jorge L; Soria, Felipe; Abbouda, Alessandro; Peña-García, Pablo

2015-01-01

To evaluate the long-term outcomes of laser in situ keratomileusis (LASIK) for high myopia with or without astigmatism. Vissum Instituto Oftalmologico de Alicante and Miguel Hernandez University, Alicante, Spain. Retrospective-prospective case series. Laser in situ keratomileusis was performed using the Visx 20/20 excimer laser. The minimum follow-up was 15 years. The main outcome measures were uncorrected (UDVA) and corrected (CDVA) distance visual acuities, manifest refraction, and corneal topography. This study included 40 patients (40 eyes) with a mean age of 51.08 years ± 6.67 (SD) (range 41 to 60 years) with high myopia (-6.00 to -18.00 diopters [D]). At 15 years, the safety index was 1.23 and the efficacy index, 0.95. During the follow-up, a significant increase in the dioptric power of all keratometric variables was detected (P≤.028, Friedman test), the most notable increase occurring between 3 months and 1 year (P≤.005). At 15 years, 46.15% of the eyes were within ±1.00 D of the attempted spherical equivalent and 64.10% were within ±2.00 D. The UDVA at 15 years was 20/25 or better in 43.59% of eyes and 20/40 or better in 64.10% of eyes. The postoperative CDVA was significantly better than preoperatively (P<.001). The postoperative complications were minor except in 1 eye in which ectasia occurred. Laser in situ keratomileusis for high myopia was safe over the long term. However, significant myopic regression with time was detected. Low preoperative pachymetry and low residual stromal bed were predictors of keratometric regression. No author has a financial or proprietary interest in any material or method mentioned. Copyright © 2015 ASCRS and ESCRS. Published by Elsevier Inc. All rights reserved.

TOPOGRAPHICALLY GUIDED LASIK FOR MYOPIA USING THE NIDEK CXII CUSTOMIZED ASPHERIC TREATMENT ZONE (CATZ)

PubMed Central

Waring, George; Dougherty, Paul J.; Chayet, Arturo; Fischer, Jeffery; Fant, Barbara; Stevens, Gary; Bains, Harkaran S.

2007-01-01

Purpose To assess the efficacy, predictability, and safety of topography-guided laser in situ keratomileusis (LASIK) for the surgical correction of low to moderate myopia with astigmatism using the Nidek CXIII excimer laser equipped with the customized aspheric treatment zone (CATz) algorithm. Methods In a multicenter US Food and Drug Administration study of topography-guided LASIK, 4 centers enrolled 135 eyes with manifest refraction sphere that ranged from −0.50 to −7.00 D (mean, −3.57 ± 1.45) with up to −4.00 D of astigmatism (mean, −1.02 ± 0.64 D). The intended outcome was plano in all eyes. Refractive outcomes and higher-order aberrations were analyzed preoperatively and postoperatively. Patient satisfaction was assessed using both the validated Refractive Status and Vision Profile (RSVP) questionnaire and a questionnaire designed for this study. Six-month postoperative outcomes are reported here. Results By 6 months postoperatively, the manifest refraction spherical equivalent (MRSE) for all eyes was −0.09 ± 0.31 D. Six months postoperatively, 116 of 131 eyes (88.55%) had an uncorrected visual acuity of 20/20 or better, and 122 of 131 eyes (93.13%) had a MRSE within ±0.50 D. Distance best spectacle-corrected visual acuity (BSCVA) increased by 2 or more lines in 21 of 131 eyes (19.01%), and no eyes lost 2 lines or more of BSCVA. The total ocular higher-order aberrations root-mean-square increased by 0.04 μm postoperatively. Patients reported significantly fewer night driving and glare and halo symptoms postoperatively than preoperatively. Conclusions Nidek CXIII CATz treatment of myopia with astigmatism is safe, efficacious, and predictable, and it reduces patient symptoms associated with night driving and glare and halo symptoms. PMID:18427614

PRK vs LASEK vs Epi-LASIK: a comparison of corneal haze, postoperative pain and visual recovery in moderate to high myopia.

PubMed

Reilly, C D; Panday, V; Lazos, V; Mittelstaedt, B R

2010-01-01

The field of refractive surgery continues to evolve amid continued concerns as to which surgical technique minimizes the risk of inducing ectasia. To compare clinical outcomes between PRK, LASEK and Epi-LASIK in moderately to highly myopic eyes (-4.00 D to -8.00 D). A retrospective chart review of 100 PRK eyes, 100 LASEK eyes (with alcohol) and 97 Epi-LASIK eyes was performed. Post-operative pain, uncorrected visual acuity, and corneal haze data was recorded and analyzed at post-op days 1, 4 and 7 and at post-op months 1, 3, 6 and 12. In all groups surgical corrections ranged from -4.00 D to -8.00 D. There was less pain associated with the epi-LASIK procedure especially early (post-op days 1 and 4). Visual recovery was superior within the PRK group during the first post-operative week but by post-op week 4 all three were equal. Haze scores were similar but a trend for less haze was demonstrated with epi-LASIK at 6 and 12 months. Epi-LASIK has a slight advantage over PRK and LASEK early on in the post-op course with regards to pain. Visual recovery is similar by 4 weeks and is better with PRK early. In addition, epi-LASIK trends toward less significant haze. © Nepal Ophthalmic Society.

Optical Quality, Threshold Target Identification and Military Target Task Performance After Advanced Keratorefractive Surgery

DTIC Science & Technology

2010-05-01

PRK vs . LASIK ) will no longer randomized but rather the patient a...commercial workstation & software. Analysis will determine the effect on visual performance of the different treatments (WFO PRK vs . WFO LASIK vs . WFG PRK ...Overall objective. To determine the effect of two types of wavefront modalities (WFG vs . WFO) and two types of refractive surgery ( PRK vs . LASIK )

Assessment of pupillary influence in LASIK patients using a digital pupillometer and VQF 25 questionnaire.

PubMed

Andrade, Eduardo Marcelo Moron de; Chamon, Wallace

2013-10-01

Identify ideal profiles in patients undergoing to photorefractive laser surgery with the aid of an automated pupillometry and psychometric analysis of patients with visual function questionnaire (VQF 25). Seventy-seven patients undergoing photorefractive laser surgery laser (LASIK) were analyzed with the aid of an automated digital pupillometer based on an infrared camera coupled to the optical head of a videokeratography system. Patients underwent complete ophthalmic evaluation and documentation of the pupillary behavior under different intensities of illumination, simulating situations of everyday life. Visual quality function questionnaire, translated to Portuguese was assessed. All patients, regardless of pupillary change under varying conditions of illumination (scotopic, mesopic and photopic) showed improvement in all sub-groups of the VQF 25. Pupil diameter was not the primary determinant of patients' visual satisfaction. Despite digital pupillometer has proven to be a useful tool in documenting and understanding of pupil behavior, a set of factors such as psycho-social profile, preoperative ametropy and final residual ametropy, contributed decisively to determine the degree of satisfaction of patients undergoing LASIK.

Wavefront-optimized laser in situ keratomileusis with the Allegretto Wave Eye-Q excimer laser and the FEMTO LDV Crystal Line femtosecond laser: 6 month visual and refractive results.

PubMed

Ziaei, Mohammed; Mearza, Ali A; Allamby, David

2015-08-01

To present the first reported series of patients undergoing myopic LASIK with the FEMTO LDV Crystal Line femtosecond laser and the WaveLight Allegretto Eye-Q excimer laser. We report the uncorrected and corrected distance visual acuity (UDVA and CDVA), refractive predictability, efficacy and safety of laser in situ keratomileusis (LASIK) performed with the above laser platforms. This prospective interventional case series study evaluated consecutive eyes with low to moderate myopic astigmatism that underwent LASIK with the FEMTO LDV Crystal Line femtosecond laser and the WaveLight Allegretto Eye-Q 400 Hz excimer laser. Visual and refractive changes as well as complications were evaluated after wavefront-optimized laser treatment. Four hundred and forty four patients (887 eyes) reached the 6-month time gate. Mean age at time of procedure was 31 years (range: 20-59). Mean pre-op spherical-equivalent (SE) was -3.44 diopters (D)±1.34D (range: -0.50 to -7.00) whilst the postoperative spherical equivalent decreased to -0.08±0.31D (range -2.25 to 1.00). At 6-month follow up, 96.9% of patients had monocular uncorrected distance visual acuity of 20/20 or better with 95.2% of patients within ±0.5D of intended refractive outcome. All patients achieved 20/20 binocular distance uncorrected visual acuity. No significant intra-operative or postoperative complications were encountered during the 6-month follow-up period. The combination of the above laser platforms provides safe, effective and predictable results in correcting compound myopic astigmatism with excellent visual outcomes. Copyright © 2015 British Contact Lens Association. Published by Elsevier Ltd. All rights reserved.

Comparison of 2 wavefront-guided excimer lasers for myopic laser in situ keratomileusis: one-year results.

PubMed

Yu, Charles Q; Manche, Edward E

2014-03-01

To compare laser in situ keratomileusis (LASIK) outcomes between 2 wavefront-guided excimer laser systems in the treatment of myopia. University eye clinic, Palo Alto, California, USA. Prospective comparative case series. One eye of patients was treated with the Allegretto Wave Eye-Q system (small-spot scanning laser) and the fellow eye with the Visx Star Customvue S4 IR system (variable-spot scanning laser). Evaluations included measurement of uncorrected visual acuity, corrected visual acuity, and wavefront aberrometry. One hundred eyes (50 patients) were treated. The mean preoperative spherical equivalent (SE) refraction was -3.89 diopters (D) ± 1.67 (SD) and -4.18 ± 1.73 D in the small-spot scanning laser group and variable-spot scanning laser group, respectively. There were no significant differences in preoperative higher-order aberrations (HOAs) between the groups. Twelve months postoperatively, all eyes in the small-spot scanning laser group and 92% in the variable-spot scanning laser group were within ±0.50 D of the intended correction (P = .04). At that time, the small-spot scanning laser group had significantly less spherical aberration (0.12 versus 0.15) (P = .04) and significantly less mean total higher-order root mean square (0.33 μm versus 0.40 μm) (P = .01). Subjectively, patients reported that the clarity of night and day vision was significantly better in the eye treated with the small-spot scanning laser. The predictability and self-reported clarity of vision of wavefront-guided LASIK were better with the small-spot scanning laser. Eyes treated with the small-spot scanning laser had significantly fewer HOAs. Copyright © 2014 ASCRS and ESCRS. Published by Elsevier Inc. All rights reserved.

Fibrin adhesive in conjunction with epithelial ingrowth removal after laser in situ keratomileusis: long-term results.

PubMed

Hardten, David R; Fahmy, Mona M; Vora, Gargi K; Berdahl, John P; Kim, Terry

2015-07-01

To describe the long-term results of fibrin adhesive use in the management of epithelial ingrowth after laser in situ keratomileusis (LASIK). Private practice, Minneapolis, Minnesota, and an academic medical center, Durham, North Carolina, USA. Retrospective case series. Patients with a history of LASIK had epithelial ingrowth removal with mechanical debridement and fibrin glue application. Visual outcomes and the presence or absence of epithelial ingrowth were evaluated again after 3 months and at the last follow-up. The main outcome measures were recurrence of epithelial ingrowth and visual acuity. Thirty-nine eyes of 38 patients were evaluated. After epithelial ingrowth removal and application of fibrin glue, 31 eyes (79.5%) had no recurrence of ingrowth at the final follow-up and 5 eyes (12.8%) had mild epithelial ingrowth not requiring removal. Three eyes (7.7%) had significant epithelial ingrowth at the 3-month follow-up that required subsequent removal and fibrin application. At the 3-month follow-up visit, 76.9% of eyes achieved 20/25 or better corrected distance visual acuity (CDVA) and 69.2% of eyes achieved 20/40 or better uncorrected distance visual acuity (UDVA). At the last follow-up visit (mean 26.6 ± 17.0 months [SD]), 84.6% of eyes had 20/25 or better CDVA and 74.4% of eyes had 20/40 or better UDVA. Fibrin adhesive in conjunction with manual epithelial removal prevented a clinically significant recurrence of epithelial ingrowth in the majority of eyes. Larger randomized studies are needed to compare the success of this technique with that of others. No author has a financial or proprietary interest in any material or method mentioned. Copyright © 2015 ASCRS and ESCRS. Published by Elsevier Inc. All rights reserved.

The effect of procedure room temperature and humidity on LASIK outcomes.

PubMed

Seider, Michael I; McLeod, Stephen D; Porco, Travis C; Schallhorn, Steven C

2013-11-01

To determine whether procedure room temperature or humidity during LASIK affect refractive outcomes in a large patient sample. Retrospective cohort study. A total of 202 394 eyes of 105 712 patients aged 18 to 75 years who underwent LASIK at an Optical Express, Inc., location in their United Kingdom and Ireland centers from January 1, 2008, to June 30, 2011, who met inclusion criteria. Patient age, gender, flap creation technique, pre- and 1-month post-LASIK manifest refraction, and ambient temperature and humidity during LASIK were recorded. Effect size determination and univariate and multivariate analyses were performed to characterize the relationships between LASIK procedure room temperature and humidity and postoperative refractive outcome. One month post-LASIK manifest refraction. No clinically significant effect of procedure room temperature or humidity was found on LASIK refractive outcomes. When considering all eyes in our population, an increase of 1°C during LASIK was associated with a 0.003 diopter (D) more hyperopic refraction 1 month postoperatively, and an increase in 1% humidity was associated with a 0.0004 more myopic refraction. These effect sizes were the same or similar when considering only myopic eyes, only hyperopic eyes, and subgroups of eyes stratified by age and preoperative refractive error. Neither procedure room temperature nor humidity during LASIK were found to have a clinically significant relationship with postoperative manifest refraction in our population. Copyright © 2013 American Academy of Ophthalmology. Published by Elsevier Inc. All rights reserved.

The effect of procedure room temperature and humidity on LASIK outcomes

PubMed Central

Seider, Michael I.; McLeod, Stephen D.; Porco, Travis C.; Schallhorn, Steven C.

2013-01-01

Objective To determine if procedure room temperature and humidity during LASIK affects refractive outcomes in a very large patient sample. Design Retrospective cohort study. Participants 202,394 eyes of 105,712 patients aged 18 to 75 years old who underwent LASIK at an Optical Express, Inc. location in their United Kingdom and Ireland centers from January 1, 2008 to June 30, 2011 who met inclusion criteria. Methods Patient age, gender, pre- and one month post-LASIK manifest refraction and flap creation technique were recorded as well as the ambient temperature and humidity during LASIK. Effect size determination, in addition to univariate and multivariate analysis was performed to characterize the relationships between LASIK procedure room temperature and humidity and post-operative refractive outcome. Main Outcome Measures One month post-LASIK manifest refraction. Results No clinically significant effect of procedure room temperature or humidity was found on LASIK refractive outcomes. When considering all eyes in our population, an increase of one degree Celsius during LASIK was associated with a 0.003 diopter more hyperopic refraction one month post-operatively and an increase in one percent humidity was associated with a 0.0004 more myopic refraction. These effect sizes were the same or similar when considering only myopic eyes, only hyperopic eyes and subgroups of eyes stratified by age and pre-operative refractive error. Conclusions Procedure room temperature or humidity during LASIK was found to have no clinically significant relationship with post-operative manifest refraction in our population. PMID:23769199

Incidence, outcomes, and risk factors for retreatment after wavefront-optimized ablations with PRK and LASIK.

PubMed

Randleman, J Bradley; White, Alfred J; Lynn, Michael J; Hu, Michelle H; Stulting, R Doyle

2009-03-01

To analyze and compare retreatment rates after wavefront-optimized photorefractive keratectomy (PRK) and LASIK and determine risk factors for retreatment. A retrospective chart review was performed to identify patients undergoing PRK or LASIK with the wavefront-optimized WaveLight platform from January 2005 through December 2006 targeted for a piano outcome and to determine the rate and risk factors for retreatment surgery in this population. Eight hundred fifty-five eyes were analyzed, including 70 (8.2%) eyes with hyperopic refractions and 785 (91.8%) eyes with myopic refractions. After initial treatment, 72% of eyes were 20/20 or better and 99.5% were 20/40 or better. To improve uncorrected visual acuity, 54 (6.3%) eyes had retreatments performed. No significant differences in retreatment rates were noted based on age (P = .15), sex (P = .8), eye (P = .3), PRK versus LASIK (P = 1.0), room temperature (P = .1) or humidity (P = .9), and no correlation between retreatment rate and month or season of primary surgery (P = .4). There was no correlation between degree of myopia and retreatment rate. Eyes were significantly more likely to undergo retreatment if they were hyperopic (12.8% vs 6.0%, P = .006) or had astigmatism > or = 1.00 diopter (D) (9.1% vs 5.3%, P = .04). Retreatment rate was 6.3% with the WaveLight ALLEGRETTO WAVE excimer laser. This rate was not influenced by age, sex, corneal characteristics, or environmental factors. Eyes with hyperopic refractions or astigmatism > or = 1.00 D were more likely to undergo retreatment.

Retrospective Analysis of the Post-Operative Changes in Higher-Order Aberrations: A Comparison of the WaveLight EX500 to the VISX S4 Laser in Refractive Surgery.

PubMed

Reed, Donovan S; Apsey, Douglas; Steigleman, Walter; Townley, James; Caldwell, Matthew

2017-11-01

In an attempt to maximize treatment outcomes, refractive surgery techniques are being directed toward customized ablations to correct not only lower-order aberrations but also higher-order aberrations specific to the individual eye. Measurement of the entirety of ocular aberrations is the most definitive means to establish the true effect of refractive surgery on image quality and visual performance. Whether or not there is a statistically significant difference in induced higher-order corneal aberrations between the VISX Star S4 (Abbott Medical Optics, Santa Ana, California) and the WaveLight EX500 (Alcon, Fort Worth, Texas) lasers was examined. A retrospective analysis was performed to investigate the difference in root-mean-square (RMS) value of the higher-order corneal aberrations postoperatively between two currently available laser platforms, the VISX Star S4 and the WaveLight EX500 lasers. The RMS is a compilation of higher-order corneal aberrations. Data from 240 total eyes of active duty military or Department of Defense beneficiaries who completed photorefractive keratectomy (PRK) or laser in situ keratomileusis (LASIK) refractive surgery at the Wilford Hall Ambulatory Surgical Center Joint Warfighter Refractive Surgery Center were examined. Using SPSS statistics software (IBM Corp., Armonk, New York), the mean changes in RMS values between the two lasers and refractive surgery procedures were determined. A Student t test was performed to compare the RMS of the higher-order aberrations of the subjects' corneas from the lasers being studied. A regression analysis was performed to adjust for preoperative spherical equivalent. The study and a waiver of informed consent have been approved by the Clinical Research Division of the 59th Medical Wing Institutional Review Board (Protocol Number: 20150093H). The mean change in RMS value for PRK using the VISX laser was 0.00122, with a standard deviation of 0.02583. The mean change in RMS value for PRK using the

Comparison of two techniques of marking the horizontal axis during excimer laser keratorefractive surgery for myopic astigmatism.

PubMed

Burka, Jenna M; Bower, Kraig S; Cute, David L; Stutzman, Richard D; Subramanian, Prem S; Rabin, Jeff C

2005-04-01

To compare two methods of limbal marking used during laser refractive surgery for myopic astigmatism. Retrospective chart review. Forty-two eyes of 42 patients who underwent photorefractive keratectomy (PRK) or laser-assisted in-situ keratomileusis (LASIK) for myopic astigmatism were marked preoperatively to identify the horizontal axis. In 18 eyes, marks were placed at the slit lamp (SL) with the slit beam set at 180 degrees as a reference. In 24 eyes, marks were placed in the laser room (LR) immediately before reclining under the laser. All treatments were performed with the Alcon LADARVision excimer laser system. Vector analysis of postoperative cylinder and reduction in cylinder and uncorrected and best-corrected visual acuity were evaluated for both groups. The mean postoperative magnitude of error was -0.19 +/- 0.44 diopters for the LR group and -0.09 +/- 0.42 diopters for the SL group (P = .439, NS). Both groups had a mean angle of error indicating an overall counterclockwise rotation of axis with an angle of error of 6.3 +/- 8.7 degrees for the LR group and 8.0 +/- 10.2 degrees for the SL group (P = .562, NS). We found no significant difference in outcomes with an overall trend toward undercorrection of cylinder in both groups, leaving room for improvement after refractive surgery for myopic astigmatism.

Composition of the excimer laser-induced plume produced during LASIK refractive surgery

NASA Astrophysics Data System (ADS)

Glickman, Randolph D.; Liu, Yun; Mayo, George L.; Baribeau, Alan D.; Starck, Tomy; Bankhead, Tom

2003-07-01

Because of concerns about potential hazards to surgical personnel of the plume associated with laser refractive surgery, this study was performed to characterize the composition of such plumes. Filter elements were removed from the smoke evacuator of a VISX S3 excimer laser (filter pore size ~0.3 microns) and from a Mastel Clean Room ( filter pore size ~0.2 microns) used with a LADARVISION excimer laser. The filters from both laser systems captured the laser-induced plumes from multiple, routine, LASIK patient procedures. Some filters were processed for scanning electron microscopy, while others were extracted with methanol and chloroform for biochemical analysis. Both the VISX "Final Air" filter and the Mastel "Clean Room" filter captured material that was not observed in filters that had clean operating room air only passed through them. In the VISX system, air flows through the filter unit parallel to the filter matrix. SEM analysis showed these filters captured discrete particles of 0.3 to 3.0 microns in size. In the Mastel Clean Room unit, air flows orthogonally through the filter, and the filter matrix was heavily layered with captured debris so that individual particles were not readily distinguished. Amino acid analysis and gel electrophoresis of extracted material revealed proteinaceous molecules as large as 5000 molecular weight. Such large molecules in the laser plume are not predicted by the existing theory of photochemical ablation. The presence of relatively large biomolecules may constitute a risk of allergenic reactions in personnel exposed to the plume, and also calls into question the precise mechanism of excimer laser photochemical ablation. Supported by the RMG Research Endowment, and Research to Prevent Blindness

Comparison of ablation centration after bilateral sequential versus simultaneous LASIK.

PubMed

Lin, Jane-Ming; Tsai, Yi-Yu

2005-01-01

To compare ablation centration after bilateral sequential and simultaneous myopic LASIK. A retrospective randomized case series was performed of 670 eyes of 335 consecutive patients who had undergone either bilateral sequential (group 1) or simultaneous (group 2) myopic LASIK between July 2000 and July 2001 at the China Medical University Hospital, Taichung, Taiwan. The ablation centrations of the first and second eyes in the two groups were compared 3 months postoperatively. Of 670 eyes, 274 eyes (137 patients) comprised the sequential group and 396 eyes (198 patients) comprised the simultaneous group. Three months post-operatively, 220 eyes of 110 patients (80%) in the sequential group and 236 eyes of 118 patients (60%) in the simultaneous group provided topographic data for centration analysis. For the first eyes, mean decentration was 0.39 +/- 0.26 mm in the sequential group and 0.41 +/- 0.19 mm in the simultaneous group (P = .30). For the second eyes, mean decentration was 0.28 +/- 0.23 mm in the sequential group and 0.30 +/- 0.21 mm in the simultaneous group (P = .36). Decentration in the second eyes significantly improved in both groups (group 1, P = .02; group 2, P < .01). The mean distance between the first and second eyes was 0.31 +/- 0.25 mm in the sequential group and 0.32 +/- 0.18 mm in the simultaneous group (P = .33). The difference of ablation center angles between the first and second eyes was 43.2 < or = 48.3 degrees in the sequential group and 45.1 +/- 50.8 degrees in the simultaneous group (P = .42). Simultaneous bilateral LASIK is comparable to sequential surgery in ablation centration.

Comparison Between Botulinum Toxin A Injection and Lacrimal Punctal Plugs for the Control of Post-LASIK Dry Eye Manifestations: A Prospective Study.

PubMed

Fouda, Sameh M; Mattout, Hala K

2017-06-01

Laser in situ keratomelieusis (LASIK) is one of the commonest refractive procedures performed nowadays. The dry eye problem is nearly universal in all patients after LASIK and it can be so annoying that the post-operative patient satisfaction is sometimes precluded. Conventional treatment includes the use of artificial tears. Alternative methods such as punctal plugs and botulinum toxin injection can be used for the management of post-LASIK dry eye. The aim of this study is to compare botulinum toxin injection in the orbicularis muscle to lacrimal punctal plugs for the control of post-LASIK dry eye manifestations. This is a prospective study that included 60 patients who had LASIK eye surgery for correction of refractive errors. Patients were randomly assigned to one of three methods of dry eye management; the first method was conventional medical treatment with preservative-free tear substitutes only (group A: 20 patients = 40 eyes); the second method was intraoperative injection of botulinum toxin A (BTA) in the orbicularis muscle below the lower punctum of both eyes (group B: 20 patients = 40 eyes) and the third method was intraoperative insertion of temporary extended duration silicone punctal plugs in the lower punctum of both eyes (group C: 20 patients = 40 eyes). In the first follow-up visit after 2 weeks, the two test groups (B, C) showed a statistically significant increase in both tear film break up time (TBUT) and Schirmer test score with a decrease in the OSDI score and daily frequency of lubricants used in comparison to the control group A. These differences were maintained in the next follow-up visit but they became statistically insignificant at the 3rd and 6th post-operative months. Complications were encountered more in the punctal plug patients (60%) than in BTA patients (25%) and this difference was statistically significant. The use of BTA injection to control dry eye symptoms by inducing temporary punctal ectropion is an effective method

Under-flap stromal bed CXL for early post-LASIK ectasia: a novel treatment technique.

PubMed

Wallerstein, Avi; Adiguzel, Eser; Gauvin, Mathieu; Mohammad-Shahi, Nima; Cohen, Mark

2017-01-01

Collagen cross-linking (CXL) for post-laser-assisted in situ keratomileusis (LASIK) ectasia (PLE) is traditionally performed either epi-on or epi-off on the corneal surface. This study describes a novel technique in treating early PLE with under-flap CXL (ufCXL) to the stromal bed and reports on 6-month outcomes. Case series of seven patients (eight eyes) with topography-diagnosed early PLE treated with ufCXL. Inclusion criteria were early, mild PLE defined as new-onset postoperative manifest refraction cylinder ≤1.50 D, with new topographic inferior steepening consistent with ectasia, uncorrected distance visual acuity (UDVA) of 20/40 or better, and corrected distance visual acuity (CDVA) of 20/25 or better. Existing LASIK flap was lifted, riboflavin was applied directly to the stromal bed, flap was repositioned, and 18 mW/cm 2 ultraviolet light was applied for 3 minutes to the corneal surface. Post-ufCXL manifest refraction, UDVA and CDVA, corneal cylinder, K max , and corneal irregularity index were compared with pre-ufCXL measurements. Patients had a pre-ufCXL sphere of 0.09±0.48 D and cylinder of -0.78±0.49 D. At 6 months, post-ufCXL sphere (0.06±0.8 D; P =0.89) and cylinder (-1.09±0.76 D, P =0.26) were unchanged. Cumulative post-ufCXL UDVA was unchanged, achieving 20/20, 20/30, and 20/40 in 25%, 88%, and 88%, respectively, compared with 13%, 63%, and 88% pre-ufCXL ( P =0.68). Post-ufCXL CDVA was unchanged ( P =0.93) with a gain of one line in two eyes, a loss of one line in one eye, and five eyes unchanged. The efficacy index ( P =0.76), safety index ( P =0.89), K max ( P =0.94), and corneal irregularity index ( P =0.73) were also unchanged. Preliminary results with ufCXL for early PLE are promising, demonstrating maintenance of visual accuracy, efficacy, safety, K max , and cylinder, with much quicker recovery times than surface CXL.

[Comparison of the effects of different side-cut angles on corneal biomechanical properties after femtosecond laser assisted-laser in situ keratomileusis].

PubMed

Li, H; Wang, Y; Dou, R; Wang, L; Xu, L L; Li, X J; Zhang, J M

2017-01-11

Objective: To evaluate the effects of side-cut angles on corneal biomechanical properties after femtosecond laser assisted-laser in situ keratomileusis (FS-LASIK). Methods: In this clinical control study, 97 right eyes of 97 patients with myopia and myopic astigmatism undergoing FS-LASIK surgery were included randomly. Two types of side-cut angles were designed for the flap, 90° in 48 eyes and 130° in 49 eyes. The values of corneal resistance factor (CRF), cornea hysteresis (CH) and 37 biomechanical waveform parameters were measured using the ocular response analyzer preoperatively and at 1 and 3 months postoperatively. The comparison between the two groups at different follow-up time points was made with one-way analysis of variance, and the comparison among different follow-up time points in each group was performed with the repeated measures analysis of variance. Results: The mean CRF, CH, p area, h, dive1, dive2, w11 and w21 in both groups showed significant reduction at 1 month postoperatively (group 90°: CRF 10.49 vs. 6.85, CH 10.02 vs. 7.55, p1 area 3 537.54 vs. 1 918.07, h1 404.74 vs. 283.25, dive1 350.63 vs. 243.33, w11 10.50 vs. 7.58. group 130°: CRF 10.14 vs. 6.38, CH 9.93 vs. 7.13, p1 area 3 498.93 vs. 2 038.74, h1 411.93 vs. 304.49, dive1 352.51 vs. 265.12, w11 10.55 vs. 7.78. P< 0.001) . The mean CRF, CH, p area, w, h, dive1 and dive2 in both groups showed significant reduction at 3 months postoperatively (group 90°: CRF 10.49 vs. 6.60, CH 10.02 vs. 7.65, p1 area 3537.54 vs. 2042.91, h1 404.74 vs. 307.77, dive1 350.63 vs. 263.33, w11 10.50 vs. 7.58. group 130°: CRF 10.14 vs. 6.45, CH 9.93 vs. 7.67, p1 area 3 498.93 vs. 2 187.97, h1 411.93 vs. 327.39, dive1 352.51 vs. 284.26, w11 10.55 vs. 7.61. P< 0.001). The mean path in both groups showed significant increase at 1 and 3 months postoperatively (group 90°: path1 23.14 vs. 30.50 vs. 30.79. group 130°: path1 24.12 vs. 32.18 vs. 31.49. P< 0.001). The mean aplhf, bindex, dive2 and path2 between

Evaluating the speed of visual recovery following thin-flap LASIK with a femtosecond laser.

PubMed

Durrie, Daniel S; Brinton, Jason P; Avila, Michele R; Stahl, Erin D

2012-09-01

To investigate the speed of visual recovery following myopic thin-flap LASIK with a femtosecond laser. This pilot study prospectively evaluated 20 eyes from 10 patients who underwent bilateral simultaneous LASIK with the Femto LDV Crystal Line femtosecond laser (Ziemer Ophthalmic Systems AG) used to create a circular flap of 9.0-mm diameter and 110-μm thickness followed by photoablation with the Allegretto Wave Eye-Q (WaveLight AG) excimer laser. Binocular and monocular uncorrected distance visual acuity (UDVA), monocular contrast sensitivity, and a patient questionnaire were evaluated during the first hours, 1 day, and 1 month postoperatively. For monocular UDVA, 100% of eyes were 20/40 at 1 hour and 100% were 20/25 at 4 hours. For binocular UDVA, all patients achieved 20/32 by 30 minutes and 20/20 by 4 hours. Low frequency contrast sensitivity returned to preoperative baseline by 1 hour (P=.73), and showed a statistically significant improvement over baseline by 4 hours (P=.01). High frequency monocular contrast sensitivity returned to preoperative baseline by 4 hours (P=.48), and showed a statistically significant improvement by 1 month (P=.04). At 2 and 4 hours, 50% and 100% of patients, respectively, indicated that they would feel comfortable driving. Visual recovery after thin-flap femtosecond LASIK is rapid, occurring within the first few hours after surgery. Copyright 2012, SLACK Incorporated.

Concept for image-guided vitreo-retinal fs-laser surgery: adaptive optics and optical coherence tomography for laser beam shaping and positioning

NASA Astrophysics Data System (ADS)

Matthias, Ben; Brockmann, Dorothee; Hansen, Anja; Horke, Konstanze; Knoop, Gesche; Gewohn, Timo; Zabic, Miroslav; Krüger, Alexander; Ripken, Tammo

2015-03-01

Fs-lasers are well established in ophthalmic surgery as high precision tools for corneal flap cutting during laser in situ keratomileusis (LASIK) and increasingly utilized for cutting the crystalline lens, e.g. in assisting cataract surgery. For addressing eye structures beyond the cornea, an intraoperative depth resolved imaging is crucial to the safety and success of the surgical procedure due to interindividual anatomical disparities. Extending the field of application even deeper to the posterior eye segment, individual eye aberrations cannot be neglected anymore and surgery with fs-laser is impaired by focus degradation. Our demonstrated concept for image-guided vitreo-retinal fs-laser surgery combines adaptive optics (AO) for spatial beam shaping and optical coherence tomography (OCT) for focus positioning guidance. The laboratory setup comprises an adaptive optics assisted 800 nm fs-laser system and is extended by a Fourier domain optical coherence tomography system. Phantom structures are targeted, which mimic tractional epiretinal membranes in front of excised porcine retina within an eye model. AO and OCT are set up to share the same scanning and focusing optics. A Hartmann-Shack sensor is employed for aberration measurement and a deformable mirror for aberration correction. By means of adaptive optics the threshold energy for laser induced optical breakdown is lowered and cutting precision is increased. 3D OCT imaging of typical ocular tissue structures is achieved with sufficient resolution and the images can be used for orientation of the fs-laser beam. We present targeted dissection of the phantom structures and its evaluation regarding retinal damage.

Intraocular lens power estimation by accurate ray tracing for eyes underwent previous refractive surgeries

NASA Astrophysics Data System (ADS)

Yang, Que; Wang, Shanshan; Wang, Kai; Zhang, Chunyu; Zhang, Lu; Meng, Qingyu; Zhu, Qiudong

2015-08-01

For normal eyes without history of any ocular surgery, traditional equations for calculating intraocular lens (IOL) power, such as SRK-T, Holladay, Higis, SRK-II, et al., all were relativley accurate. However, for eyes underwent refractive surgeries, such as LASIK, or eyes diagnosed as keratoconus, these equations may cause significant postoperative refractive error, which may cause poor satisfaction after cataract surgery. Although some methods have been carried out to solve this problem, such as Hagis-L equation[1], or using preoperative data (data before LASIK) to estimate K value[2], no precise equations were available for these eyes. Here, we introduced a novel intraocular lens power estimation method by accurate ray tracing with optical design software ZEMAX. Instead of using traditional regression formula, we adopted the exact measured corneal elevation distribution, central corneal thickness, anterior chamber depth, axial length, and estimated effective lens plane as the input parameters. The calculation of intraocular lens power for a patient with keratoconus and another LASIK postoperative patient met very well with their visual capacity after cataract surgery.

Structural and functional changes in corneal innervation after laser in situ keratomileusis and their relationship with dry eye.

PubMed

Chao, Cecilia; Stapleton, Fiona; Zhou, Xiangtian; Chen, Shihao; Zhou, Shi; Golebiowski, Blanka

2015-11-01

The most likely etiology of post-LASIK dry eye is corneal nerve damage; however, no direct relationship between post-LASIK dry eye symptoms and nerve damage has been established, and limited information is available about the relationship between dry eye signs and corneal reinnervation after LASIK. Tear neuropeptides (SP and CGRP) are important in the maintenance of corneal nerve health, but the impact of LASIK has not yet been studied. This study evaluated changes in nerve morphology, tear neuropeptide, and dry eye, so as to establish the relationship between reinnervation and dry eye and to assess the role of tear neuropeptides in reinnervation post-LASIK. Twenty non-dry eye volunteers who had undergone bilateral myopic-LASIK completed this study. Corneal nerve morphology (density, width, interconnections, and tortuosity), SP and CGRP concentration, and dry eye were monitored over time prior to, 1 day, 1 week, 1, 3, and 6 months post-LASIK. Dry eye symptoms and tear function, except for osmolarity (P = 0.003), remained unchanged post-LASIK. Corneal nerve morphology decreased immediately, and did not return to preoperative levels by 6 months post-LASIK (P < 0.001). Increased tear SP concentration was observed 3 months post-LASIK (P < 0.001). Associations between reinnervation as measured by increased density and lower tear SP (P = 0.03), and between increased density and decreased dry eye symptoms (P = 0.01) were found post-LASIK. An inverse relationship between reinnervation post-LASIK and dry eye symptoms was found, confirming that post-LASIK dry eye is a neuropathic disease. This study is the first to demonstrate an association between tear SP and post-LASIK reinnervation, suggesting that strategies for manipulating neuropeptide concentration to improve reinnervation may improve ocular comfort post-LASIK.

Evaluation of corneal biomechanics in patients with keratectasia following LASIK using dynamic Scheimpflug analyzer.

PubMed

Ueki, Ryotaro; Maeda, Naoyuki; Fuchihata, Mutsumi; Asai, Tomoko; Koh, Shizuka; Fujimoto, Hisataka; Uematsu, Masafumi; Nishida, Kohji

2018-04-26

To investigate the corneal biomechanics in eyes with keratectasia following LASIK using a dynamic Scheimpflug analyzer. Case-Control study. The subjects in the study included 12 eyes with keratectasia after LASIK (KE), 24 eyes with keratoconus (KC), 17 eyes without keratectasia after LASIK (LASIK), and 34 eyes with normal corneas (Normal). Corneal biomechanics of the four groups were evaluated using a dynamic Scheimpflug analyzer. Compared with Normal (7.06 ± 0.54), the radius at the highest concavity (radius, mm) of LASIK (5.96 ± 0.76), KE (4.93 ± 0.61) and KC (5.39 ± 1.02) were significantly small. The Deflection Amplitude (HCDLA, mm) of Normal (0.94 ± 0.07) was significantly lower than those of KE (1.11 ± 0.10) and KC (1.06 ± 0.16), and was not significantly different from that of LASIK (0.98 ± 0.07). There were significant differences between LASIK and KE in radius and HCDLA (P < 0.05), whereas KE and KC had no differences in these parameters. Corneal biomechanical features evaluated using the dynamic Scheimpflug analyzer suggest that biomechanical properties in eyes with keratectasia, keratoconus, and LASIK are different from those of normal eyes. Although the biomechanics in eyes with keratectasia differs from that in eyes with LASIK, it is similar to that in eyes with keratoconus.

Placido disk-based topography versus high-resolution rotating Scheimpflug camera for corneal power measurements in keratoconic and post-LASIK eyes: reliability and agreement.

PubMed

Penna, Rachele R; de Sanctis, Ugo; Catalano, Martina; Brusasco, Luca; Grignolo, Federico M

2017-01-01

To compare the repeatability/reproducibility of measurement by high-resolution Placido disk-based topography with that of a high-resolution rotating Scheimpflug camera and assess the agreement between the two instruments in measuring corneal power in eyes with keratoconus and post-laser in situ keratomileusis (LASIK). One eye each of 36 keratoconic patients and 20 subjects who had undergone LASIK was included in this prospective observational study. Two independent examiners worked in a random order to take three measurements of each eye with both instruments. Four parameters were measured on the anterior cornea: steep keratometry (Ks), flat keratometry (Kf), mean keratometry (Km), and astigmatism (Ks-Kf). Intra-examiner repeatability and inter-examiner reproducibility were evaluated by calculating the within-subject standard deviation (Sw) the coefficient of repeatability (R), the coefficient of variation (CoV), and the intraclass correlation coefficient (ICC). Agreement between instruments was tested with the Bland-Altman method by calculating the 95% limits of agreement (95% LoA). In keratoconic eyes, the intra-examiner and inter-examiner ICC were >0.95. As compared with measurement by high-resolution Placido disk-based topography, the intra-examiner R of the high-resolution rotating Scheimpflug camera was lower for Kf (0.32 vs 0.88), Ks (0.61 vs 0.88), and Km (0.32 vs 0.84) but higher for Ks-Kf (0.70 vs 0.57). Inter-examiner R values were lower for all parameters measured using the high-resolution rotating Scheimpflug camera. The 95% LoA were -1.28 to +0.55 for Kf, -1.36 to +0.99 for Ks, -1.08 to +0.50 for Km, and -1.11 to +1.48 for Ks-Kf. In the post-LASIK eyes, the intra-examiner and inter-examiner ICC were >0.87 for all parameters. The intra-examiner and inter-examiner R were lower for all parameters measured using the high-resolution rotating Scheimpflug camera. The intra-examiner R was 0.17 vs 0.88 for Kf, 0.21 vs 0.88 for Ks, 0.17 vs 0.86 for Km, and 0

Placido disk-based topography versus high-resolution rotating Scheimpflug camera for corneal power measurements in keratoconic and post-LASIK eyes: reliability and agreement

PubMed Central

Penna, Rachele R.; de Sanctis, Ugo; Catalano, Martina; Brusasco, Luca; Grignolo, Federico M.

2017-01-01

AIM To compare the repeatability/reproducibility of measurement by high-resolution Placido disk-based topography with that of a high-resolution rotating Scheimpflug camera and assess the agreement between the two instruments in measuring corneal power in eyes with keratoconus and post-laser in situ keratomileusis (LASIK). METHODS One eye each of 36 keratoconic patients and 20 subjects who had undergone LASIK was included in this prospective observational study. Two independent examiners worked in a random order to take three measurements of each eye with both instruments. Four parameters were measured on the anterior cornea: steep keratometry (Ks), flat keratometry (Kf), mean keratometry (Km), and astigmatism (Ks-Kf). Intra-examiner repeatability and inter-examiner reproducibility were evaluated by calculating the within-subject standard deviation (Sw) the coefficient of repeatability (R), the coefficient of variation (CoV), and the intraclass correlation coefficient (ICC). Agreement between instruments was tested with the Bland-Altman method by calculating the 95% limits of agreement (95% LoA). RESULTS In keratoconic eyes, the intra-examiner and inter-examiner ICC were >0.95. As compared with measurement by high-resolution Placido disk-based topography, the intra-examiner R of the high-resolution rotating Scheimpflug camera was lower for Kf (0.32 vs 0.88), Ks (0.61 vs 0.88), and Km (0.32 vs 0.84) but higher for Ks-Kf (0.70 vs 0.57). Inter-examiner R values were lower for all parameters measured using the high-resolution rotating Scheimpflug camera. The 95% LoA were -1.28 to +0.55 for Kf, -1.36 to +0.99 for Ks, -1.08 to +0.50 for Km, and -1.11 to +1.48 for Ks-Kf. In the post-LASIK eyes, the intra-examiner and inter-examiner ICC were >0.87 for all parameters. The intra-examiner and inter-examiner R were lower for all parameters measured using the high-resolution rotating Scheimpflug camera. The intra-examiner R was 0.17 vs 0.88 for Kf, 0.21 vs 0.88 for Ks, 0.17 vs 0

The effect of topical apraclonidine on subconjunctival hemorrhage and flap adherence in LASIK patients.

PubMed

Aslanides, loannis M; Tsiklis, Nikolaos S; Ozkilic, Efekan; Coskunseven, Efekan; Pallikaris, loannis G; Jankov, Mirko R

2006-06-01

To determine whether the use of topical apraclonidine just before the LASIK procedure prevents subconjunctival hemorrhage and to study its effect on postoperative flap adherence. Topical apraclonidine 0.125% was randomly applied to 1 eye of 66 myopic patients who underwent primary bilateral LASIK. Apraclonidine was instilled 1 hour prior to and 30 seconds before placing the vacuum ring of the microkeratome, whereas the other eye served as control. Thirty minutes after the operation, all patients were examined by the surgeon to evaluate hyperemia and identify flap-related complications (eg, slippage, dislocation, or flap folds). The size of subconjunctival hemorrhage was also evaluated on postoperative days 1 and 7. All 132 eyes in the study were examined after surgery to identify flap folds and/or their dislocation. In the apraclonidine group, 48 (72.8%) eyes had no hyperemia, 16 (24.2%) eyes had mild hyperemia, 2 (3%) eyes had moderate hyperemia, and no (0%) eyes had severe hyperemia. In the control group, 37 (56.1%) eyes had mild hyperemia, 21 (31.8%) eyes had moderate hyperemia, 1 (1.5%) eye had severe hyperemia, and 7 (10.6%) eyes had no hyperemia. In the apraclonidine group, 44 (66.7%) eyes had no subconjunctival hemorrhage (grade 0); grade 1 was present in 19 (28.8%) eyes whereas grades 2 and 3 were present in 2 (3%) eyes and 1 (1.5%) eye, respectively. In the control group, 19 (28.8%) eyes showed grade 0, 13 (19.7%) eyes had grade 1, and grades 2 and 3 were present in 20 (30.3%) eyes and 14 (21.2%) eyes, respectively. Chi-square test showed a highly significant difference between the two groups (P < .001). No flap-related problems were reported in either group. Topical apraclonidine applied before LASIK surgery may prevent immediate postoperative hyperemia and prolonged subconjunctival hemorrhage by its alpha-mimetic vasoconstrictor effect without inducing flap adherence complication.

The Recovery of Optical Quality after Laser Vision Correction

PubMed Central

Jung, Hyeong-Gi

2013-01-01

Purpose To evaluate the optical quality after laser in situ keratomileusis (LASIK) or serial photorefractive keratectomy (PRK) using a double-pass system and to follow the recovery of optical quality after laser vision correction. Methods This study measured the visual acuity, manifest refraction and optical quality before and one day, one week, one month, and three months after laser vision correction. Optical quality parameters including the modulation transfer function, Strehl ratio and intraocular scattering were evaluated with a double-pass system. Results This study included 51 eyes that underwent LASIK and 57 that underwent PRK. The optical quality three months post-surgery did not differ significantly between these laser vision correction techniques. Furthermore, the preoperative and postoperative optical quality did not differ significantly in either group. Optical quality recovered within one week after LASIK but took between one and three months to recover after PRK. The optical quality of patients in the PRK group seemed to recover slightly more slowly than their uncorrected distance visual acuity. Conclusions Optical quality recovers to the preoperative level after laser vision correction, so laser vision correction is efficacious for correcting myopia. The double-pass system is a useful tool for clinical assessment of optical quality. PMID:23908570

Refractive surgery for accommodative esotropia: 5-year follow-up.

PubMed

Magli, Adriano; Forte, Raimondo; Gallo, Flavio; Carelli, Roberta

2014-02-01

To assess the long-term effectiveness and safety of refractive surgery with LASIK or photorefractive keratectomy (PRK) for treating accommodative esotropia in adults. All patients with accommodative esotropia treated with LASIK or PRK until December 2007 and with a minimum follow-up of 5 years were retrospectively included. LASIK was performed on 44 eyes of 22 patients (12 women, 10 men; mean age: 22.7 ± 2.9 years). Mean postoperative follow-up was 62.1 ± 3.2 months. PRK was performed on 16 eyes of 8 patients (4 women, 4 men; mean age: 23.7 ± 1.7 years). Mean postoperative follow-up was 61.3 ± 2.8 months. At the 5-year follow-up, the mean cycloplegic refraction was more hyperopic in the PRK group (0.3 ± 0.8 vs 0.06 ± 0.3 diopters, P = .01). Correction of esotropia to esophoria or orthotropia was present in 21 patients (95.4%) treated with LASIK and in all patients treated with PRK. Both LASIK and PRK were effective in the long-term reduction of accommodative esotropia. Copyright 2014, SLACK Incorporated.

A Novel Laser Refractive Surgical Treatment for Presbyopia: Optics-Based Customization for Improved Clinical Outcome.

PubMed

Pajic, Bojan; Pajic-Eggspuehler, Brigitte; Mueller, Joerg; Cvejic, Zeljka; Studer, Harald

2017-06-13

Laser Assisted in Situ Keratomileusis (LASIK) is a proven treatment method for corneal refractive surgery. Surgically induced higher order optical aberrations were a major reason why the method was only rarely used to treat presbyopia, an age-related near-vision loss. In this study, a novel customization algorithm for designing multifocal ablation patterns, thereby minimizing induced optical aberrations, was used to treat 36 presbyopic subjects. Results showed that most candidates went from poor visual acuity to uncorrected 20/20 vision or better for near (78%), intermediate (92%), and for distance (86%) vision, six months after surgery. All subjects were at 20/25 or better for distance and intermediate vision, and a majority (94%) were also better for near vision. Even though further studies are necessary, our results suggest that the employed methodology is a safe, reliable, and predictable refractive surgical treatment for presbyopia.

Endophthalmitis due to inadvertent globe penetration during retrobulbar injection of saline solution for laser in situ keratomileusis.

PubMed

Han, Ying; Lam, Har Hiu; Stewart, Jay M

2009-06-01

A 31-year-old woman presented with visual acuity of counting fingers and presumed bacterial endophthalmitis in the left eye 10 days after refractive surgery. During the procedure, a retrobulbar injection of balanced salt solution had been performed to assist with globe suction by the microkeratome. A perforation site was identified in the inferonasal retina. Following intravitreal antibiotic injection and surgical intervention, the visual acuity returned to 20/20. Retrobulbar injection to facilitate laser in situ keratomileusis carries risks. Careful monitoring for signs of infection is recommended if globe perforation is recognized.

Visual outcomes after Epi-LASIK and PRK for low and moderate myopia.

PubMed

Sia, Rose K; Coe, Charles D; Edwards, Jayson D; Ryan, Denise S; Bower, Kraig S

2012-01-01

To evaluate visual outcomes following epi-LASIK compared to photorefractive keratectomy (PRK). Of a total 294 patients aged ≥21 years, 145 (290 eyes) underwent epi-LASIK and 149 (298 eyes) underwent PRK for low to moderate myopia or myopic astigmatism. Epi-LASIK was performed with the Amadeus II epikeratome (Abbott Medical Optics) and PRK with the Amoils rotary epithelial brush (Innovative Excimer Solutions). All ablations were performed using the same excimer laser system. Outcome measures included intraoperative complications, corneal reepithelialization, postoperative pain, uncorrected distance visual acuity (UDVA), manifest refraction spherical equivalent (MRSE), corrected distance visual acuity (CDVA), corneal haze, and quality of vision. Mean preoperative MRSE was -2.97±1.19 diopters (D) for epi-LASIK versus -2.95±1.06 D for PRK. Complete reepithelialization was achieved by postoperative day 4 in 46.9% of epi-LASIK eyes versus 92.4% of PRK eyes, with superior UDVA at postoperative day 1 in the PRK group (P=.002). Using Fisher exact test, a significantly higher percentage of epi-LASIK eyes compared to PRK eyes achieved 20/15 or better at 1 month (25.8% vs 17.8%, P=.031), 3 months (62.3% vs 49.3%, P=.004), 6 months (77.1% vs 57.9%, P<.001), and 12 months (75.9% vs 61.9%, P=.002). A change in MRSE >0.50 D occurred in 8.4% of epi-LASIK eyes within the 3- and 12-month interval versus 17.7% of PRK eyes (P=.04). No differences were noted between the two procedures in CDVA or clinically significant haze. Epi-LASIK showed superior refractive efficacy and stability but required more time for wound healing, resulting in inferior early visual outcomes and a tendency to overcorrect higher refractive errors compared to PRK. Both treatments were safe and comparable in terms of pain and haze formation. Copyright 2012, SLACK Incorporated.

[Comparison of Discriminant Analysis and Decision Trees for the Detection of Subclinical Keratoconus].

PubMed

Kleinhans, Sonja; Herrmann, Eva; Kohnen, Thomas; Bühren, Jens

2017-08-15

Background Iatrogenic keratectasia is one of the most dreaded complications of refractive surgery. In most cases, keratectasia develops after refractive surgery of eyes suffering from subclinical stages of keratoconus with few or no signs. Unfortunately, there has been no reliable procedure for the early detection of keratoconus. In this study, we used binary decision trees (recursive partitioning) to assess their suitability for discrimination between normal eyes and eyes with subclinical keratoconus. Patients and Methods The method of decision tree analysis was compared with discriminant analysis which has shown good results in previous studies. Input data were 32 eyes of 32 patients with newly diagnosed keratoconus in the contralateral eye and preoperative data of 10 eyes of 5 patients with keratectasia after laser in-situ keratomileusis (LASIK). The control group was made up of 245 normal eyes after LASIK and 12-month follow-up without any signs of iatrogenic keratectasia. Results Decision trees gave better accuracy and specificity than did discriminant analysis. The sensitivity of decision trees was lower than the sensitivity of discriminant analysis. Conclusion On the basis of the patient population of this study, decision trees did not prove to be superior to linear discriminant analysis for the detection of subclinical keratoconus. Georg Thieme Verlag KG Stuttgart · New York.

Under-flap stromal bed CXL for early post-LASIK ectasia: a novel treatment technique

PubMed Central

Wallerstein, Avi; Adiguzel, Eser; Gauvin, Mathieu; Mohammad-Shahi, Nima; Cohen, Mark

2017-01-01

Purpose Collagen cross-linking (CXL) for post-laser-assisted in situ keratomileusis (LASIK) ectasia (PLE) is traditionally performed either epi-on or epi-off on the corneal surface. This study describes a novel technique in treating early PLE with under-flap CXL (ufCXL) to the stromal bed and reports on 6-month outcomes. Patients and methods Case series of seven patients (eight eyes) with topography-diagnosed early PLE treated with ufCXL. Inclusion criteria were early, mild PLE defined as new-onset postoperative manifest refraction cylinder ≤1.50 D, with new topographic inferior steepening consistent with ectasia, uncorrected distance visual acuity (UDVA) of 20/40 or better, and corrected distance visual acuity (CDVA) of 20/25 or better. Existing LASIK flap was lifted, riboflavin was applied directly to the stromal bed, flap was repositioned, and 18 mW/cm2 ultraviolet light was applied for 3 minutes to the corneal surface. Post-ufCXL manifest refraction, UDVA and CDVA, corneal cylinder, Kmax, and corneal irregularity index were compared with pre-ufCXL measurements. Results Patients had a pre-ufCXL sphere of 0.09±0.48 D and cylinder of −0.78±0.49 D. At 6 months, post-ufCXL sphere (0.06±0.8 D; P=0.89) and cylinder (−1.09±0.76 D, P=0.26) were unchanged. Cumulative post-ufCXL UDVA was unchanged, achieving 20/20, 20/30, and 20/40 in 25%, 88%, and 88%, respectively, compared with 13%, 63%, and 88% pre-ufCXL (P=0.68). Post-ufCXL CDVA was unchanged (P=0.93) with a gain of one line in two eyes, a loss of one line in one eye, and five eyes unchanged. The efficacy index (P=0.76), safety index (P=0.89), Kmax (P=0.94), and corneal irregularity index (P=0.73) were also unchanged. Conclusion Preliminary results with ufCXL for early PLE are promising, demonstrating maintenance of visual accuracy, efficacy, safety, Kmax, and cylinder, with much quicker recovery times than surface CXL. PMID:28031696

LASIK flap buttonhole treated immediately by PRK with mitomycin C.

PubMed

Kymionis, George D; Portaliou, Dimitra M; Karavitaki, Alexandra E; Krasia, Maria S; Kontadakis, Georgios A; Stratos, Aimilianos; Yoo, Sonia H

2010-03-01

To describe the visual outcomes of three patients who had LASIK flap buttonhole and were treated immediately with photorefractive keratectomy (PRK) and topical mitomycin C (MMC) 0.02%. Three patients underwent bilateral LASIK with the SCHWIND Carriazo-Pendula 90 microm head microkeratome. In all three cases, a buttonhole flap occurred in the left eye. The flap was repositioned and phototherapeutic keratectomy for 50 microm was used for epithelial removal while immediate PRK with MMC was performed to treat the buttonhole flap. Three months after the procedure, uncorrected distance visual acuity and corrected distance visual acuity were 20/20 with regular topographic findings. Using PRK with MCC immediately after the occurrence of the LASIK flap buttonhole may be an effective treatment.

Comparison of the visual results after SMILE and femtosecond laser-assisted LASIK for myopia.

PubMed

Lin, Fangyu; Xu, Yesheng; Yang, Yabo

2014-04-01

To perform a comparative clinical analysis of the safety, efficacy, and predictability of two surgical procedures (ie, small incision lenticule extraction [SMILE] and femtosecond laser-assisted LASIK [FS-LASIK]) to correct myopia. Sixty eyes of 31 patients with a mean spherical equivalent of -5.13 ± 1.75 diopters underwent myopia correction with the SMILE procedure. Fifty-one eyes of 27 patients with a mean spherical equivalent of -5.58 ± 2.41 diopters were treated with the FS-LASIK procedure. Postoperative uncorrected and corrected distance visual acuity, manifest refraction, and higher-order aberrations were analyzed statistically at 1 and 3 months postoperatively. No statistically significant differences were found at 1 and 3 months in parameters that included the percentage of eyes with an uncorrected distance visual acuity of 20/20 or better (P = .556, .920) and mean spherical equivalent refraction (P = .055, .335). At 1 month, 4 SMILE-treated eyes and 1 FS-LASIK-treated eye lost one or more line of visual acuity (P = .214, chi-square test). At 3 months, 2 SMILE-treated eyes lost one or more line of visual acuity, whereas all FS-LASIK-treated eyes had an unchanged or corrected distance visual acuity. Higher-order aberrations and spherical aberration were significantly lower in the SMILE group than the FS-LASIK group at 1 (P = .007, .000) and 3 (P = .006, .000) months of follow-up. SMILE and FS-LASIK are safe, effective, and predictable surgical procedures to treat myopia. SMILE has a lower induction rate of higher-order aberrations and spherical aberration than the FS-LASIK procedure. Copyright 2014, SLACK Incorporated.

Higher order aberrations and relative risk of symptoms after LASIK.

PubMed

Sharma, Munish; Wachler, Brian S Boxer; Chan, Colin C K

2007-03-01

To understand what level of higher order aberrations increases the relative risk of visual symptoms in patients after myopic LASIK. This study was a retrospective comparative analysis of 103 eyes of 62 patients divided in two groups, matched for age, gender, pupil size, and spherical equivalent refraction. The symptomatic group comprised 36 eyes of 24 patients after conventional LASIK with different laser systems evaluated in our referral clinic and the asymptomatic control group consisted of 67 eyes of 38 patients following LADARVision CustomCornea wavefront LASIK. Comparative analysis was performed for uncorrected visual acuity (UCVA), best spectacle-corrected visual acuity (BSCVA), contrast sensitivity, refractive cylinder, and higher order aberrations. Wavefront analysis was performed with the LADARWave aberrometer at 6.5-mm analysis for all eyes. Blurring of vision was the most common symptom (41.6%) followed by double image (19.4%), halo (16.7%), and fluctuation in vision (13.9%) in symptomatic patients. A statistically significant difference was noted in UCVA (P = .001), BSCVA (P = .001), contrast sensitivity (P < .001), and manifest cylinder (P = .001) in the two groups. The percentage difference between the symptomatic and control group mean root-mean-square (RMS) values ranged from 157% to 206% or 1.57 to 2.06 times greater. Patients with visual symptoms after LASIK have significantly lower visual acuity and contrast sensitivity and higher mean RMS values for higher order aberrations than patients without symptoms. Root-mean-square values of greater than two times the normal after-LASIK population for any given laser platform may increase the relative risk of symptoms.

A Novel Laser Refractive Surgical Treatment for Presbyopia: Optics-Based Customization for Improved Clinical Outcome

PubMed Central

Pajic, Bojan; Pajic-Eggspuehler, Brigitte; Mueller, Joerg; Cvejic, Zeljka; Studer, Harald

2017-01-01

Laser Assisted in Situ Keratomileusis (LASIK) is a proven treatment method for corneal refractive surgery. Surgically induced higher order optical aberrations were a major reason why the method was only rarely used to treat presbyopia, an age-related near-vision loss. In this study, a novel customization algorithm for designing multifocal ablation patterns, thereby minimizing induced optical aberrations, was used to treat 36 presbyopic subjects. Results showed that most candidates went from poor visual acuity to uncorrected 20/20 vision or better for near (78%), intermediate (92%), and for distance (86%) vision, six months after surgery. All subjects were at 20/25 or better for distance and intermediate vision, and a majority (94%) were also better for near vision. Even though further studies are necessary, our results suggest that the employed methodology is a safe, reliable, and predictable refractive surgical treatment for presbyopia. PMID:28608800

Spring-action Apparatus for Fixation of Eyeball (SAFE): a novel, cost-effective yet simple device for ophthalmic wet-lab training.

PubMed

Ramakrishnan, Seema; Baskaran, Prabu; Fazal, Romana; Sulaiman, Syed Mohammad; Krishnan, Tiruvengada; Venkatesh, Rengaraj

2016-10-01

Achieving a formed and firm eyeball which is stably fixed in a holding device is a major challenge of surgical wet-lab training. Our innovation, the 'Spring-action Apparatus for Fixation of Eyeball (SAFE)' is a robust, simple and economical device to solve this problem. It consists of a hollow iron cylinder to which a spring-action syringe is attached. The spring-action syringe generates vacuum and enables reliable fixation of a human or animal cadaveric eye on the iron cylinder. The rise in intraocular pressure due to vacuum fixation can be varied as per need or nature of surgery being practised. A mask-fixed version of this device is also designed to train surgeons for appropriate hand positioning. An experienced surgeon performed various surgeries including manual small incision cataract surgery (MSICS), phacoemulsification, laser in situ keratomileusis (LASIK), femtosecond LASIK docking, Descemet's stripping endothelial keratoplasty, deep anterior lamellar keratoplasty, penetrating keratoplasty and trabeculectomy on this device, while a trainee surgeon practised MSICS and wound suturing. Skill-appropriate comfort level was much higher with SAFE than with conventional globe holders for both surgeons. Due to its stability, pressure adjustability, portability, cost-efficiency and simplicity, we recommend SAFE as the basic equipment for every wet lab. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://www.bmj.com/company/products-services/rights-and-licensing/

Myopic keratomileusis by excimer laser on a lathe.

PubMed

Ganem, S; Aron-Rosa, D; Gross, M; Rosolen, S

1994-01-01

We designed an excimer laser keratomileusis delivery system to increase the regularity of the refractive cut surface and allow greater precision in the level and shape of the ablated zone. A parallel faced corneal disc was produced by microkeratectomy from six human eyes and surgical keratectomy in 12 beagle corneas. A 193-nanometer excimer laser that was used to project an oval beam onto the corneal disc was rotated on a flat surface to ensure overlapping of the ovally ablated areas between pulses. Electron microscopy of eye bank lenticules demonstrated a circular smooth regularly concave ablation zone. Histological examination of nine clear corneas confirmed thinning of the stroma without fibroblastic reaction and no epithelial hypertrophy. Mean preoperative corneal power of 43.15 +/- 2.18 decreased postoperatively to 33.61 +/- 2.34. The new technique of excimer laser keratomileusis has the advantage of a cut surface smoother and the clear zone is devoid of the stepwise concavity and irregularity seen in diaphragm based photoablation delivery systems.

Combined intrastromal astigmatic keratotomy and laser in situ keratomileusis flap followed by photoablation to correct post-penetrating keratoplasty ametropia and high astigmatism: One-year follow-up.

PubMed

Shalash, Riad B; Elshazly, Malak I; Salama, Marwa M

2015-10-01

To evaluate a new technique combining intrastromal astigmatic keratotomy (AK) with a laser in situ keratomileusis (LASIK) flap followed by excimer laser photoablation to correct post-penetrating keratoplasty (PKP) high astigmatism and ametropia. Kasr El Aini Hospital, Cairo University, Cairo, Egypt. Prospective interventional uncontrolled case series. Patients with post-PKP high astigmatism and ametropia had paired intrastromal AK with LASIK flap using the M2 microkeratome followed 2 to 3 months later by excimer laser photoablation. The main outcome measures were uncorrected distance visual acuity (UDVA), corrected distance visual acuity (CDVA), mean refractive spherical equivalent (SE), and mean cylinder after each step and at the 1-year follow-up. The study comprised 20 eyes (20 patients). All parameters were significantly improved in all patients by the last follow-up visit. The mean UDVA improved from 1.07 logMAR ± 0.2 (SD) preoperatively to 0.23 ± 0.18 logMAR (P < .001), the mean CDVA improved from 0.79 ± 0.18 logMAR to 0.12 ± 0.12 logMAR (P < .001), the mean refractive SE improved from -5.04 ± 2.62 diopters (D) to -1.47 ± 1.32 D (P = .001), and the mean cylinder reduced from -5.39 ± 0.98 D to -1.05 ± 0.71 D (P < .001). The mean correction index was 0.84 ± 0.10, and the mean flattening index was 0.83 ± 0.10. Thirty-five percent of cases developed microperforations, and 15% developed epithelial ingrowth. This combined approach allowed for the correction of high astigmatism and ametropia following PKP; however, epithelial ingrowth requiring intervention is a complication to be considered. No author has a financial or proprietary interest in any material or method mentioned. Copyright © 2015 ASCRS and ESCRS. Published by Elsevier Inc. All rights reserved.

Incidence and Outcomes of Optical Zone Enlargement and Recentration After Previous Myopic LASIK by Topography-Guided Custom Ablation.

PubMed

Reinstein, Dan Z; Archer, Timothy J; Carp, Glenn I; Stuart, Alastair J; Rowe, Elizabeth L; Nesbit, Andrew; Moore, Tara

2018-02-01

To report the incidence, visual and refractive outcomes, optical zone enlargement, and recentration using topography-guided CRS-Master TOSCA II software with the MEL 80 excimer laser (Carl Zeiss Meditec AG, Jena, Germany) after primary myopic laser refractive surgery. Retrospective analysis of 73 eyes (40 patients) with complaints of night vision disturbances due to either a decentration or small optical zone following a primary myopic laser refractive surgery procedure using the MEL 80 laser. Multiple ATLAS topography scans were imported into the CRS-Master software for topography-guided ablation planning. The topography-guided re-treatment procedure was performed as either a LASIK flap lift, a new LASIK flap, a side cut only, or photorefractive keratectomy. Axial curvature maps were analyzed using a fixed grid and set of concentric circles superimposed to measure the topographic optical zone diameter and centration. Follow-up was 12 months. The incidence of use in the population of myopic treatments during the study period was 0.79% (73 of 9,249). The optical zone diameter was increased by 11% from a mean of 5.65 to 6.32 mm, with a maximum change of 2 mm in one case. Topographic decentration was reduced by 64% from a mean of 0.58 to 0.21 mm. There was a 44% reduction in spherical aberration, 53% reduction in coma, and 39% reduction in total higher order aberrations. A subjective improvement in night vision symptoms was reported by 93%. Regarding efficacy, 82% of eyes reached 20/20 and 100% reached 20/32 (preoperative CDVA was 20/20 or better in 90%). Regarding safety, no eyes lost two lines of CDVA and 27% gained one line. Regarding predictability, 71% of re-treatments were within ±0.50 diopters. Topography-guided ablation was effective in enlarging the optical zone, recentering the optical zone, and reducing higher order aberrations. Topography-guided custom ablation appears to be an effective method for re-treatment procedures of symptomatic patients after

Comparison of a hydrogel corneal inlay and monovision laser in situ keratomileusis in presbyopic patients: focus on visual performance and optical quality.

PubMed

Verdoorn, Cornelis

2017-01-01

To compare the visual performance and optical quality after Raindrop Near Vision Inlay implantation or monovision LASIK for the correction of presbyopia. In this retrospective case-series study, patients previously treated in the nondominant eye with monovision LASIK were compared with patients previously implanted with Raindrop Near Vision Inlay. The study enrolled 16 inlay and 15 monovision LASIK patients. Uncorrected near visual acuity, uncorrected distance visual acuity, binocular stereopsis, patient satisfaction, and patient task performance were assessed. Postoperatively, the mean spherical equivalent was -0.66 D (0.78 SD) for the inlay group and -1.03 D (0.56 SD) for the monovision LASIK group. Monocularly, at uncorrected near distances, 60% of inlay patients and 47% of monovision LASIK patients achieved ≥20/20. Monocularly, at uncorrected far distances, 75% of inlay patients and 40% of monovision LASIK patients achieved ≥20/32 vision. Binocularly, at near distances, 79% of inlay patients and 53% of monovision LASIK patients obtained ≥20/20 vision. All patients achieved ≥20/20 binocularly for distance. On average, inlay patients obtained 98 seconds of arc and monovision LASIK patients obtained 286 seconds of arc for stereopsis. Most (79%) of the inlay patients and 66% of monovision LASIK patients were satisfied with their near vision, while 86% of inlay patients and 67% of monovision LASIK patients were satisfied with their distance vision. Patients receiving corneal inlays demonstrated better near and distance visual acuities, binocular stereopsis, task performance, and satisfaction, when compared to patients treated with monovision LASIK.

Using complex networks towards information retrieval and diagnostics in multidimensional imaging

NASA Astrophysics Data System (ADS)

Banerjee, Soumya Jyoti; Azharuddin, Mohammad; Sen, Debanjan; Savale, Smruti; Datta, Himadri; Dasgupta, Anjan Kr; Roy, Soumen

2015-12-01

We present a fresh and broad yet simple approach towards information retrieval in general and diagnostics in particular by applying the theory of complex networks on multidimensional, dynamic images. We demonstrate a successful use of our method with the time series generated from high content thermal imaging videos of patients suffering from the aqueous deficient dry eye (ADDE) disease. Remarkably, network analyses of thermal imaging time series of contact lens users and patients upon whom Laser-Assisted in situ Keratomileusis (Lasik) surgery has been conducted, exhibit pronounced similarity with results obtained from ADDE patients. We also propose a general framework for the transformation of multidimensional images to networks for futuristic biometry. Our approach is general and scalable to other fluctuation-based devices where network parameters derived from fluctuations, act as effective discriminators and diagnostic markers.

Using complex networks towards information retrieval and diagnostics in multidimensional imaging.

PubMed

Banerjee, Soumya Jyoti; Azharuddin, Mohammad; Sen, Debanjan; Savale, Smruti; Datta, Himadri; Dasgupta, Anjan Kr; Roy, Soumen

2015-12-02

We present a fresh and broad yet simple approach towards information retrieval in general and diagnostics in particular by applying the theory of complex networks on multidimensional, dynamic images. We demonstrate a successful use of our method with the time series generated from high content thermal imaging videos of patients suffering from the aqueous deficient dry eye (ADDE) disease. Remarkably, network analyses of thermal imaging time series of contact lens users and patients upon whom Laser-Assisted in situ Keratomileusis (Lasik) surgery has been conducted, exhibit pronounced similarity with results obtained from ADDE patients. We also propose a general framework for the transformation of multidimensional images to networks for futuristic biometry. Our approach is general and scalable to other fluctuation-based devices where network parameters derived from fluctuations, act as effective discriminators and diagnostic markers.

[Clinical observation on the relation between laser in situ keratomileusis treating myopic anisometropia and binocular vision].

PubMed

Huang, Jing; Lu, Wei

2009-09-29

To analyze the effect of LASIK on visual quality of anisometropia, and evaluate its clinical value in the view of visual quality. Prospective observational case series. Assayed the naked vision, glasses-corrected vision and binocular vision of 45 cases with anisometropia >or= 2.25D before and after the operation of LASIK. 91.57% of the eyes after the operation reached the vision >or= 0.8, which says a significant improvement for binocular vision after the operation (P < 0.05). There was a significant difference on diopter between the pre-operation and post-operation (P < 0.05). As for anisometropia, there was no significant difference between simultaneous binocular visions (P = 0.431), but there was of great significance among combined, short and long distance stereopsis visions (P = 0.000). Binocular vision deteriorated as anisometropia increased (P < 0.05). The short distance stereopsis visions of LASIK-treated myopic anisometropia were better than that of glasses-corrected patients (P < 0.05). The operation of LASIK can improve the visual quality and resume the binocular vision. LASIK can correct anisometropia and its therapeutic efficacy deserves to confirm.

[Cyclorotation of the eye in wavefront-guided LASIK using a static eyetracker with iris recognition].

PubMed

Kohnen, T; Kühne, C; Cichocki, M; Strenger, A

2007-01-01

Centration of the ablation zone decisively influences the result of wavefront-guided LASIK. Cyclorotation of the eye occurs as the patient changes from the sitting position during aberrometry to the supine position during laser surgery and may lead to induction of lower and higher order aberrations. Twenty patients (40 eyes) underwent wavefront-guided LASIK (B&L 217z 100 excimer laser) with a static eyetracker driven by iris recognition (mean preoperative SE: -4.72+/-1.45 D; range: -1.63 to -7.00 D). The iris patterns of the patients' eyes were memorized during aberrometry and after flap creation. The mean absolute value of the measured cyclorotation was -1.5+/-4.2 degrees (range: -11.0 to 6.9 degrees ). The mean cyclorotation was 3.5+/-2.7 masculine (range: 0.1 to 11.0 degrees ). In 65% of all eyes cyclorotation was >2 masculine. A static eyetracker driven by iris recognition demonstrated that cyclorotation of up to 11 degrees may occur in myopic and myopic astigmatic eyes when changing from a sitting to a supine position. Use of static eyetrackers with iris recognition may provide a more precise positioning of the ablation profile as they detect and compensate cyclorotation.

Corneal limbal marking in the treatment of myopic astigmatism with the excimer laser.

PubMed

Bucher, Celine; Zuberbuhler, Bruno; Goggin, Michael; Esterman, Adrian; Schipper, Isaak

2010-07-01

To determine whether preoperative marking of the limbal cornea improves treatment of myopic astigmatism with the excimer laser. Retrospective study on 108 eyes with myopic astigmatism that underwent LASIK or laser epithelial keratomileusis (LASEK) with the Technolas 217 (Bausch & Lomb) excimer laser. Preoperative limbal marking was performed in 47 eyes (marked group). The 12-month results were used for refractive and visual analysis. The achieved cylinder reduction, spherical reduction, and refractive predictability were similar for the marked and unmarked groups in the overall study collective, in the LASIK and LASEK subgroup analysis, and in a higher astigmatism (> 1.25 diopters) subgroup analysis. Limbal marking showed no influence on the refractive results, and vector analysis showed no significant difference in angle of error among groups. Corneal limbal marking failed to improve the refractive outcome in LASIK and LASEK for myopic astigmatism.

Femtosecond laser eye surgery: the first clinical experience

NASA Astrophysics Data System (ADS)

Juhasz, Tibor; Kurtz, Ron M.; Horvath, Christopher; Suarez, Carlos G.; Nordan, Lee; Slade, Steven

2002-04-01

A brief review of commercial applications of femtosecond lasers in a clinical setting with emphasis on applications to corneal surgery is presented. The first clinical results of 208 procedures conducted from June to November 2000 is reported. The results show that femtosecond lasers may be safely used as keratome for use in LASIK procedures.