Reproducibility of intraocular pressure peak and fluctuation of the water-drinking test.

PubMed

Hatanaka, Marcelo; Alencar, Luciana M; De Moraes, Carlos G; Susanna, Remo

2013-01-01

The water-drinking test has been used as a stress test to evaluate the drainage system of the eye. However, in order to be clinically applicable,a test must provide reproducible results with consistent measurements. This study was performed to verify the reproducibility of intraocular pressure peaks and fluctuation detected during the water-drinking test in patients with ocular hypertension and open-angle glaucoma. A prospective analysis of patients in a tertiary care unit for glaucoma treatment. Twenty-four ocular hypertension and 64 open-angle glaucoma patients not under treatment. The water-drinking test was performed in 2 consecutive days by the same examiners in patients not under treatment. Reproducibility was assessed using the intraclass correlation coefficient. Peak and fluctuation of intraocular pressure obtained with the water-drinking test were analysed for reproducibility. Eighty-eight eyes from 24 ocular hypertension and 64 open-angle glaucoma patients not under treatment were evaluated. Test and retest intraocular pressure peak values were 28.38 ± 4.64 and 28.38 ± 4.56 mmHg, respectively (P = 1.00). Test and retest intraocular pressure fluctuation values were 5.75 ± 3.9 and 4.99 ± 2.7 mmHg, respectively (P = 0.06). Based on intraclass coefficient, reproducibility was excellent for peak intraocular pressure (intraclass correlation coefficient = 0.79) and fair for intraocular pressure fluctuation (intraclass correlation coefficient = 0.37). Intraocular pressure peaks detected during the water-drinking test presented excellent reproducibility, whereas the reproducibility of fluctuation was considered fair. © 2012 The Authors. Clinical and Experimental Ophthalmology © 2012 Royal Australian and New Zealand College of Ophthalmologists.

Optic nerve head blood flow response to reduced ocular perfusion pressure by alteration of either the blood pressure or intraocular pressure.

PubMed

Wang, Lin; Cull, Grant A; Fortune, Brad

2015-04-01

To test the hypothesis that blood flow autoregulation in the optic nerve head has less reserve to maintain normal blood flow in the face of blood pressure-induced ocular perfusion pressure decrease than a similar magnitude intraocular pressure-induced ocular perfusion pressure decrease. Twelve normal non-human primates were anesthetized by continuous intravenous infusion of pentobarbital. Optic nerve blood flow was monitored by laser speckle flowgraphy. In the first group of animals (n = 6), the experimental eye intraocular pressure was maintained at 10 mmHg using a saline reservoir connected to the anterior chamber. The blood pressure was gradually reduced by a slow injection of pentobarbital. In the second group (n = 6), the intraocular pressure was slowly increased from 10 mmHg to 50 mmHg by raising the reservoir. In both experimental groups, optic nerve head blood flow was measured continuously. The blood pressure and intraocular pressure were simultaneously recorded in all experiments. The optic nerve head blood flow showed significant difference between the two groups (p = 0.021, repeat measures analysis of variance). It declined significantly more in the blood pressure group compared to the intraocular pressure group when the ocular perfusion pressure was reduced to 35 mmHg (p < 0.045) and below. There was also a significant interaction between blood flow changes and the ocular perfusion pressure treatment (p = 0.004, adjusted Greenhouse & Geisser univariate test), indicating the gradually enlarged blood flow difference between the two groups was due to the ocular perfusion pressure decrease. The results show that optic nerve head blood flow is more susceptible to an ocular perfusion pressure decrease induced by lowering the blood pressure compared with that induced by increasing the intraocular pressure. This blood flow autoregulation capacity vulnerability to low blood pressure may provide experimental evidence related to the

[Intraocular pressure after ND: YAG laser capsulotomy in pseudophakic patients with glaucoma].

PubMed

Sesar, Antonio; Petric, Irena; Sesar, Ivanka; Lacmnovic-Loncar, Valentina; Jurisić, Darija; Tomić, Zeljka; Mandić, Zdravko

2006-01-01

The aim of the study was to analyze changes in intraocular pressure after Nd: YAG laser capsulotomy in pseudophakic patients with glaucoma. Intraocular pressure was recorded before, and 1 and 3 hours after YAG laser capsulotomy in 69 pseudophakic patients with glaucoma. Twenty eight patients received no therapy before capsulotomy, 21 patients received topical brimonidine 0.2%, and 20 patients received topical dorzolamide 2% 1 hour before laser capsulotomy. All patients received topical tropicamide 1% and tetracaine 0.5%. Nd: YAG laser posterior capsulotomy was performed using inverted-U technique to make a 3-4 mm diameter capsulotomy. After capsulotomy, all eyes received topical fluorometholone for 10 days. A pressure rise was greater in patients without any therapy before YAG laser capsulotomy. Eight patients with glaucoma showed intraocular pressure rise of 5 mm Hg, and 2 patients pressure rise of 10 mm Hg after laser capsulotomy. A reduction of intraocular pressure rise was found in patients who received dorzolamide 2% or brimonidine 0.2%, only 1 patient in each group developed a pressure rise of 5 mm Hg. In all patients a significant pressure rise developed within the first hour. It is difficult to compare different studies due to different techniques of cataract surgery and different intraocular lense material and design. Barnes showed that 6 of 29 (21%) developed a pressure rise of 5 mm Hg, and 1 of 29 (3%) patients a pressure rise of 10 mm Hg. In our study, 29% of patients had a pressure rise of > or =5 mm Hg, and 7% of patients had a rise of > or =10 mm Hg after laser capsulotomy. These results may be associated with a large proportion of extracapsular cataract extraction (71%) versus phacoemulsification (29%) in our patients. Pretreatment with dorzolamide 2% or brimonidine 0.2% reduce the intraocular pressure rise after Nd: YAG laser capsulotomy in pseudophakic patients with glaucoma.

Intermediate-term and long-term outcome of piggyback drainage: connecting glaucoma drainage device to a device in-situ for improved intraocular pressure control.

PubMed

Dervan, Edward; Lee, Edward; Giubilato, Antonio; Khanam, Tina; Maghsoudlou, Panayiotis; Morgan, William H

2017-11-01

This study provides results of a treatment option for patients with failed primary glaucoma drainage device. The study aimed to describe and evaluate the long-term intraocular pressure control and complications of a new technique joining a second glaucoma drainage device directly to an existing glaucoma drainage device termed 'piggyback drainage'. This is a retrospective, interventional cohort study. Eighteen eyes of 17 patients who underwent piggyback drainage between 2004 and 2013 inclusive have been studied. All patients had prior glaucoma drainage device with uncontrolled intraocular pressure. The piggyback technique involved suturing a Baerveldt (250 or 350 mm) or Molteno3 glaucoma drainage device to an unused scleral quadrant and connecting the silicone tube to the primary plate bleb. Failure of intraocular pressure control defined as an intraocular pressure greater than 21 mmHg on maximal therapy on two separate occasions or further intervention to control intraocular pressure. The intraocular pressure was controlled in seven eyes (39%) at last follow-up with a mean follow-up time of 74.2 months. The mean preoperative intraocular pressure was 27.1 mmHg (95% confidence interval 23.8-30.3) compared with 18.4 mmHg (95% confidence interval 13.9-22.8) at last follow-up. The mean time to failure was 57.1 months (95% confidence interval 32.2-82), and the mean time to further surgery was 72.3 months (95% confidence interval 49.9-94.7). Lower preoperative intraocular pressure was associated with longer duration of intraocular pressure control (P = 0.048). If the intraocular pressure was controlled over 2 years, it continued to be controlled over the long term. Two eyes (11%) experienced corneal decompensation. Piggyback drainage represents a viable surgical alternative for the treatment of patients with severe glaucoma with failing primary glaucoma drainage device, particularly in those at high risk of corneal decompensation. © 2017 Royal Australian and New Zealand

The effect of intraocular gas and fluid volumes on intraocular pressure.

PubMed

Simone, J N; Whitacre, M M

1990-02-01

Large increases in the intraocular pressure (IOP) of postoperative gas-containing eyes may require the removal of gas or fluid to reduce the IOP to the normal range. Application of the ideal gas law to Friedenwald's equation provides a mathematical model of the relationship between IOP, intraocular gas and fluid volumes, and the coefficient of scleral rigidity. This mathematic model shows that removal of a given volume of gas or fluid produces an identical decrease in IOP and that the more gas an eye contains, the greater the volume reduction necessary to reduce the pressure. Application of the model shows that the effective coefficient of scleral rigidity is low (mean K, 0.0021) in eyes with elevated IOP that have undergone vitrectomy and retinal cryopexy and very low (mean K, 0.0013) in eyes with elevated IOP that have undergone placement of a scleral buckle and band. By using the appropriate mean coefficient of rigidity, the volume of material to be aspirated to produce a given decrease in IOP can be predicted with clinically useful accuracy.

Evaluating the risk of eye injuries: intraocular pressure during high speed projectile impacts.

PubMed

Duma, Stefan M; Bisplinghoff, Jill A; Senge, Danielle M; McNally, Craig; Alphonse, Vanessa D

2012-01-01

To evaluate the risk of eye injuries by determining intraocular pressure during high speed projectile impacts. A pneumatic cannon was used to impact eyes with a variety of projectiles at multiple velocities. Intraocular pressure was measured with a small pressure sensor inserted through the optic nerve. A total of 36 tests were performed on 12 porcine eyes with a range of velocities between 6.2 m/s and 66.5 m/s. Projectiles selected for the test series included a 6.35  mm diameter metal ball, a 9.25  mm diameter aluminum rod, and an 11.16  mm diameter aluminum rod. Experiments were designed with velocities in the range of projectile consumer products such as toy guns. A range of intraocular pressures ranged between 2017 mmHg to 26,426 mmHg (39 psi-511 psi). Four of the 36 impacts resulted in globe rupture. Intraocular pressures dramatically above normal physiological pressure were observed for high speed projectile impacts. These pressure data provide critical insight to chronic ocular injuries and long-term complications such as glaucoma and cataracts.

Corn silk aqueous extracts and intraocular pressure of systemic and non-systemic hypertensive subjects.

PubMed

George, Gladys O; Idu, Faustina K

2015-03-01

Hypotensive properties have been attributed to the stigma/style of Zea mays L (corn silk). Although the effect of corn silk extract on blood pressure has been documented in animal studies, we are not aware of any study on its effect on human blood pressure and intraocular pressure. A randomised study was carried out on the effect of water only, masked doses of corn silk aqueous extract (60, 130, 192.5 and 260 mg/kg body weight) on intraocular pressure and blood pressure of 20 systemic and 20 non-systemic hypertensive subjects. Intraocular pressure and blood pressure were measured at baseline and every hour for eight hours after administering water or a masked dose of corn silk aqueous extract. Each dose was administered at two-week intervals to each subject in the two study groups. The results showed that the last three doses of corn silk aqueous extract gave a statistically significant reduction (p < 0.001) in mean intraocular pressure and blood pressure within eight hours of administration. The peak effect on intraocular pressure was observed after four hours and this was preceded by the peak effect on blood pressure, which occurred after three hours of administration. The hypotensive effect was dose-dependent in the two groups. Corn silk aqueous extract has a lowering effect on intraocular pressure in systemic and non-systemic hypertensive subjects. This may have resulted from the fall in blood pressure that is due to potassium-induced natriuresis and diuresis caused by the high potassium content in the high doses of the corn silk extract. © 2015 The Authors. Clinical and Experimental Optometry © 2015 Optometry Australia.

Ocular onchocerciasis in the Yanomami communities from Brazilian Amazon: effects on intraocular pressure.

PubMed

Herzog-Neto, Guilherme; Jaegger, Karen; Nascimento, Erika S do; Marchon-Silva, Verônica; Banic, Dalma M; Maia-Herzog, Marilza

2014-01-01

To determine the influence of onchocercal eye disease on the intraocular pressure of the Yanomami Tribe Aratha-ú of Roraima State, Brazil, considered endemic for onchocerciasis, a total of 86 patients were submitted to an ophthalmologic exam that included external examination, slit lamp examination, intraocular pressure measurement, and a fundus ophthalmoscope examination. A high prevalence of onchocerciasis-related eye lesions was encountered in 68.6% of the patients. Punctate keratitis and microfilariae in the anterior chamber were found in ∼28%. The mean of intraocular eye pressure found was 10.47 mm of Hg.

Ocular Onchocerciasis in the Yanomami Communities from Brazilian Amazon: Effects on Intraocular Pressure

PubMed Central

Herzog-Neto, Guilherme; Jaegger, Karen; do Nascimento, Erika S.; Marchon-Silva, Verônica; Banic, Dalma M.; Maia-Herzog, Marilza

2014-01-01

To determine the influence of onchocercal eye disease on the intraocular pressure of the Yanomami Tribe Aratha-ú of Roraima State, Brazil, considered endemic for onchocerciasis, a total of 86 patients were submitted to an ophthalmologic exam that included external examination, slit lamp examination, intraocular pressure measurement, and a fundus ophthalmoscope examination. A high prevalence of onchocerciasis-related eye lesions was encountered in 68.6% of the patients. Punctate keratitis and microfilariae in the anterior chamber were found in ∼28%. The mean of intraocular eye pressure found was 10.47 mm of Hg. PMID:24297812

Intraocular pressure and retinal vascular changes during transient exposure to microgravity.

PubMed

Mader, T H; Gibson, C R; Caputo, M; Hunter, N; Taylor, G; Charles, J; Meehan, R T

1993-03-15

We measured intraocular pressures and retinal vascular diameters from 11 subjects during 20 seconds of microgravity produced by parabolic flight on board a KC-135 aircraft. Intraocular pressures increased 58% during parabolic flight compared to baseline values (19 +/- 1 mm Hg vs 12 +/- 1 mm Hg, respectively; P < .001). A 4% reduction in the caliber of retinal arteries was also noted during microgravity, but this change did not achieve statistical significance (7.8 +/- 0.3 pixels at zerogravity vs 8.1 +/- 0.3 pixels at 1g; P = .07). The increase in intraocular pressure and trend of arteries to constrict are thought to result from cephalad shifts in intravascular and extravascular body fluids as a result of the absence of the 1g hydrostatic gradient. The results of our study confirm that this fluid shift and its effects on the eye occur rapidly, within 20 seconds of exposure to microgravity.

The influence of intraocular pressure and air jet pressure on corneal contactless tonometry tests.

PubMed

Simonini, Irene; Pandolfi, Anna

2016-05-01

The air puff is a dynamic contactless tonometer test used in ophthalmology clinical practice to assess the biomechanical properties of the human cornea and the intraocular pressure due to the filling fluids of the eye. The test is controversial, since the dynamic response of the cornea is governed by the interaction of several factors which cannot be discerned within a single measurement. In this study we describe a numerical model of the air puff tests, and perform a parametric analysis on the major action parameters (jet pressure and intraocular pressure) to assess their relevance on the mechanical response of a patient-specific cornea. The particular cornea considered here has been treated with laser reprofiling to correct myopia, and the parametric study has been conducted on both the preoperative and postoperative geometries. The material properties of the cornea have been obtained by means of an identification procedure that compares the static biomechanical response of preoperative and postoperative corneas under the physiological IOP. The parametric study on the intraocular pressure suggests that the displacement of the cornea׳s apex can be a reliable indicator for tonometry, and the one on the air jet pressure predicts the outcomes of two or more distinct measurements on the same cornea, which can be used in inverse procedures to estimate the material properties of the tissue. Copyright © 2015 Elsevier Ltd. All rights reserved.

Effect of marihuana on intraocular and blood pressure in glaucoma.

PubMed

Merritt, J C; Crawford, W J; Alexander, P C; Anduze, A L; Gelbart, S S

1980-03-01

Marihuana inhalation was accompanied by increased heart rate and decreased intraocular and blood pressure in 18 subjects with heterogenous glaucomas. The hypotensive effects appeared in 60 to 90 minutes as the decrease in intraocular pressure (IOP) appeared to follow the decrease in blood pressure. In addition to any local effect, the mechanism of lowered to any local effect, the mechanism of lowered IOP may also involve the decreased pressure perfusing the ciliary body vasculature as a result of the peripheral vasodilatory properties of marihuana. Postural hypotension, tachycardia, palpitations, and alterations in mental status occurred with such frequency as to mitigate against the routine used in the general glaucoma population. Our data indicate that further research should be directed to local means of delivering the ocular hypotensive cannabinoid to the glaucomatous eye.

Apparatus and method for non-contact, acoustic resonance determination of intraocular pressure

DOEpatents

Sinha, Dipen N.; Wray, William O.

1994-01-01

Apparatus and method for measuring intraocular pressure changes in an eye under investigation by detection of vibrational resonances therein. An ultrasonic transducer operating at its resonant frequency is amplitude modulated and swept over a range of audio frequencies in which human eyes will resonate. The output therefrom is focused onto the eye under investigation, and the resonant vibrations of the eye observed using a fiber-optic reflection vibration sensor. Since the resonant frequency of the eye is dependent on the pressure therein, changes in intraocular pressure may readily be determined after a baseline pressure is established.

Apparatus and method for non-contact, acoustic resonance determination of intraocular pressure

DOEpatents

Sinha, D.N.; Wray, W.O.

1994-12-27

The apparatus and method for measuring intraocular pressure changes in an eye under investigation by detection of vibrational resonances therein. An ultrasonic transducer operating at its resonant frequency is amplitude modulated and swept over a range of audio frequencies in which human eyes will resonate. The output therefrom is focused onto the eye under investigation, and the resonant vibrations of the eye observed using a fiber-optic reflection vibration sensor. Since the resonant frequency of the eye is dependent on the pressure therein, changes in intraocular pressure may readily be determined after a baseline pressure is established. 3 figures.

STS-41 crewmembers conduct DSO 0472 Intraocular Pressure on OV-103's middeck

NASA Image and Video Library

1990-10-10

STS-41 crewmembers conduct Detailed Supplementary Objective (DSO) 0472 Intraocular Pressure on the middeck of Discovery, Orbiter Vehicle (OV) 103. Mission Specialist (MS) William M. Shepherd rests his head on the stowed treadmill while Pilot Robert D. Cabana, holding Shepherd's eye open, prepares to measure Shepherd's intraocular pressure using a tono pen (in his right hand). Objectives include: establishing a database of changes in intraocular pressures that can be used to evaluate crew health; validating ten degree head down bedrest as a model for cephalad fluid shifts in microgravity; facilitating the interpretation of data by providing a quantative measure of microgravity induced cephalad fluid shifts; and validating the tono pen as an effective tool for diagnostic and scientific data collection.

Real-time display of flow-pressure-volume loops.

PubMed

Morozoff, P E; Evans, R W

1992-01-01

Graphic display of respiratory waveforms can be valuable for monitoring the progress of ventilated patients. A system has been developed that can display flow-pressure-volume loops as derived from a patient's respiratory circuit in real time. It can also display, store, print, and retrieve ventilatory waveforms. Five loops can be displayed at once: current, previous, reference, "ideal," and previously saved. Two components, the data-display device (DDD) and the data-collection device (DCD), comprise the system. An IBM 286/386 computer with a graphics card (VGA) and bidirectional parallel port is used for the DDD; an eight-bit microprocessor card and an A/D convertor card make up the DCD. A real-time multitasking operating system was written to control the DDD, while the DCD operates from in-line assembly code. The DCD samples the pressure and flow sensors at 100 Hz and looks for a complete flow waveform pattern based on flow slope. These waveforms are then passed to the DDD via the mutual parallel port. Within the DDD a process integrates the flow to create a volume signal and performs a multilinear regression on the pressure, flow, and volume data to calculate the elastance, resistance, pressure offset, and coefficient of determination. Elastance, resistance, and offset are used to calculate Pr and Pc where: Pr[k] = P[k]-offset-(elastance.V[k]) and Pc[k] = P[k]-offset-(resistance.F[k]). Volume vs. Pc and flow vs. Pr can be displayed in real time. Patient data from previous clinical tests were loaded into the device to verify the software calculations. An analog waveform generator was used to simulate flow and pressure waveforms that validated the system.(ABSTRACT TRUNCATED AT 250 WORDS)

[Hormonal homeostasis and intraocular pressure in chronic emotional stress caused by influences acting on the amygdala].

PubMed

Isakova, L S; Danilov, G E; Egorkina, S B; Butolin, E G

1989-01-01

Changes in intraocular pressure, eye hydrodynamics and the amount of hypophyseal, thyroid, adrenal and pancreatic hormones were studied during continuous stimulation of amygdaloid complex or after administration of angiotensin II into the structure in rabbits. The effects involved changes in hormonal homeostasis and elevation of intraocular pressure due to a hypersecretion of intraocular fluid. The administration of angiotensin II during the amygdala stimulation enhanced the changes.

[Association between two different types of strangling and intraocular pressure variation in jiu-jitsu athletes].

PubMed

Scarpi, Marinho Jorge; Conte, Marcelo; Rossin, Reginaldo Alexandre; Skubs, Renato; Lenk, Rudolf Eberhard; Brant, Rodrigo

2009-01-01

To verify the association between two different types of strangling with intraocular pressure variation in jiu-jitsu athletes. An observational study was performed on 9 athletes of jiu-jitsu, with at least 6 month of training, male, aged 20 to 30 years, without any physical and eyeball lesions. Associations between intraocular pressure and Cross Choke from the guard strangling (E1), and E2 - Cross Choke from mount strangling were gotten. Intraocular pressure was determined by using Perkins tonometer, at first in the absence of physical exercise over the last 24 hours and after each strangling. Then it was carried out the intraocular pressure measure at each 3 minutes, during 12 minutes of exercise recovery (R1, R2, R3, and R4) keeping the athletes lied down. Statistical analysis was done using ANOVA test and Bonferroni post-test. Meaningful reduction of both eyes intraocular pressure occurred at the E2 situation comparing to the E1 situation at all exercise recovery measures: R1 (OD: 8.22 +/- 1.39 vs.11.33 +/- 2.00 / OE: 8.55 +/- 1.23 vs. 11.88 +/- 1.90), R2 (OD: 8.44 +/- 1.87 vs.10.22 +/- 2.53 / OE: 9.00 +/- 1.80 vs. 10.44 +/- 2.35), R3 (OD: 8.44 +/- 1.74 vs.9.78 +/- 2.54 / OE: 8.55 +/- 1.42 vs. 10.33 +/- 1.93) all with p<0,01 e R4 (OD: 8.88 +/- 2.08 vs.9.55 +/- 2.87 / OE: 9.11 +/- 1.53 vs. 10.44 +/- 2.18) with p<0.05. Meaningful IOP reduction (p<0.05) was observed at the R1 moment of E2 strangling (OD: 10.77 +/- 1.92 vs.8.22 +/- 1.39 / OE: 11.44 +/- 1.94 vs. 8.55 +/- 1.23). There is association between intraocular pressure and jiu-jitsu strangling exercises, with intraocular pressure reduction.

Effects of Different Intensities of Exercise on Intraocular Pressure

ERIC Educational Resources Information Center

Rowe, Deryl; And Others

1976-01-01

The decrease in intraocular pressure during exercise and the first few minutes of recovery is related to a decrease in blood pH and an increase in blood lactate concentration, not to the intensity of the exercise. (MB)

Evidence for a GPR18 Role in Diurnal Regulation of Intraocular Pressure

PubMed Central

Miller, Sally; Leishman, Emma; Oehler, Olivia; Daily, Laura; Murataeva, Natalia; Wager-Miller, Jim; Bradshaw, Heather; Straiker, Alex

2016-01-01

Purpose The diurnal cycling of intraocular pressure (IOP) was first described in humans more than a century ago. This cycling is preserved in other species. The physiologic underpinning of this diurnal variation in IOP remains a mystery, even though elevated pressure is indicated in most forms of glaucoma, a common cause of blindness. Once identified, the system that underlies diurnal variation would represent a natural target for therapeutic intervention. Methods Using normotensive mice, we measured the regulation of ocular lipid species by the enzymes fatty acid amide hydrolase (FAAH) and N-arachidonoyl phosphatidylethanolamine phospholipase (NAPE-PLD), mRNA expression of these enzymes, and their functional role in diurnal regulation of IOP. Results We now report that NAPE-PLD and FAAH mice do not exhibit a diurnal cycling of IOP. These enzymes produce and break down acylethanolamines, including the endogenous cannabinoid anandamide. The diurnal lipid profile in mice shows that levels of most N-acyl ethanolamines and, intriguingly, N-arachidonoyl glycine (NAGly), decline at night: NAGly is a metabolite of arachidonoyl ethanolamine and a potent agonist at GPR18 that lowers intraocular pressure. The GPR18 blocker O1918 raises IOP during the day when pressure is low, but not at night. Quantitative PCR analysis shows that FAAH mRNA levels rise with pressure, suggesting that FAAH mediates the changes in pressure. Conclusions Our results support FAAH-dependent NAGly action at GPR18 as the physiologic basis of the diurnal variation of intraocular pressure in mice. PMID:27893106

The effect of vitrectomy with silicone oil tamponade on intraocular pressure and anterior chamber morphology.

PubMed

Suic, S P; Sikić, J

2001-01-01

We measured the tamponading effect of silicone oil, saline and air after vitrectomy, on intraocular pressure and aqueous humor outflow in 85 patients with highly proliferative retina and vitreous changes. Silicone oil as retinal tamponading agent after vitrectomy was used in 45 patients, and saline or air in 39 patients. The mean intraocular pressure measured at one month after treatment was greatly elevated in patients with silicone oil tamponade as compared to those with saline or air tamponade. At 6 and 12 months examinations, mean intraocular pressures were compared in these two groups of patients. Gonioscopy revealed silicone oil emulsification and presence of emulsified bubbles in the anterior chamber in 22.22% of patients, and narrowing of the chamber angle in several patients with silicone oil tamponade. Intraocular pressure elevation following vitrectomy with silicone oil tamponade was found to be of transient rather than permanent nature, since it regressed after silicone oil removal. This transient elevation was due to silicone oil tendency to emulsify. Silicone oil bubbles changed the morphology of the anterior chamber angle and fine trabecular structures by creating a barrier to aqueous humor outflow.

Effects of silibinin hemisuccinate on the intraocular pressure in normotensive rabbits.

PubMed

Mohammed, Haider M; Abdulrazzaq, Munaf H; Hussain, Saad A

2007-09-01

To evaluate the effects of silibinin hemisuccinate on the normal intraocular pressure (IOP) in rabbits. This study took place in the Department of Pharmacology and Toxicology, College of Pharmacy, University of Baghdad during the period from January to June 2005. Twenty-five New Zealand white rabbits weighing 1.5-2.5 kg were used in this study. The effects of corneal instillation of various concentrations of silibinin hemisuccinate (0.5%, 0.75% and 1%) dissolved in arachis oil, on the normal intraocular pressure in rabbits were evaluated using indentation tonometry; in addition to the possible modulation of normal IOP-recovery time after intravenous infusion of 20% sodium chloride solution. The results showed that within 30 minutes of application, silibinin in various concentrations significantly reduces IOP in comparison to baseline values (p<0.05), with greater reduction being achieved with 0.75%. The effect of IOP reduction lasts 2-3 hours and proportionate to the concentration used. Moreover, remarkable delay in IOP recovery was observed after instillation of silibinin compared with the vehicle treated (arachis oil) animals, indicating interference with aqueous humor formation. The results obtained in this study provide experimental evidences for the effectiveness of silibinin in the reduction of IOP and possible modulation of its regulatory mechanisms.

Intraocular pressure-lowering effect of oral paracetamol and its in vitro corneal penetration properties

PubMed Central

Mohamed, Nabiel; Meyer, David

2013-01-01

Background Several studies have confirmed the ability of cannabinoids to reduce intraocular pressure. Experimental data recently demonstrated unequivocally that the analgesic effect of paracetamol is due to its indirect action on cannabinoid receptors. The question then arises as to whether paracetamol can reduce intraocular pressure via its effect on intraocular cannabinoid receptors. Methods A 2-week, prospective, randomized, controlled, single-center, parallel-group pilot study was carried out to determine the efficacy and safety of paracetamol 1 g orally administered every 6 hours in adult patients with primary or secondary open angle glaucoma as compared with topical levobunolol 0.5% twice a day. Patient well-being was closely monitored throughout the study and focused on hepatic safety in accordance with Drug-Induced Liver Injury Network criteria. The in vitro diffusion kinetics of acetaminophen in a phosphate-buffered solution in rabbit and human corneas was also investigated, with the view to a topical application. Results Eighteen adult patients were enrolled in the study, with nine in the topical levobunolol group and nine in the oral paracetamol group. In the levobunolol group, the mean reduction in intraocular pressure at day 7 was 7.5 mmHg (P < 0.008) and at day 14 was 9.1 mmHg (P < 0.005), from a mean baseline intraocular pressure of 29.6 mmHg. The corresponding figures for the paracetamol group were 8.8 mmHg (P < 0.0004) at day 7 and 6.5 mmHg (P < 0.004) at day 14, from a mean baseline intraocular pressure of 29.4 mmHg. Both study regimens were well tolerated. No serious treatment-related adverse events were reported in either of the treatment groups. Liver function tests, systolic/diastolic blood pressure, or heart rate remained unchanged in both groups during the 2 weeks of the study. In the laboratory study, paracetamol 1 mg/mL in phosphate-buffered solution (pH 7.4) showed acceptable flux rates. Steady-state levels were achieved within 12 hours

The Advanced Glaucoma Intervention Study (AGIS): 7. The relationship between control of intraocular pressure and visual field deterioration.The AGIS Investigators.

PubMed

2000-10-01

To investigate the association between control of intraocular pressure after surgical intervention for glaucoma and visual field deterioration. In the Advanced Glaucoma Intervention Study, eyes were randomly assigned to one of two sequences of glaucoma surgery, one beginning with argon laser trabeculoplasty and the other trabeculectomy. In the present article we examine the relationship between intraocular pressure and progression of visual field damage over 6 or more years of follow-up. In the first analysis, designated Predictive Analysis, we categorize 738 eyes into three groups based on intraocular pressure determinations over the first three 6-month follow-up visits. In the second analysis, designated Associative Analysis, we categorize 586 eyes into four groups based on the percent of 6-month visits over the first 6 follow-up years in which eyes presented with intraocular pressure less than 18 mm Hg. The outcome measure in both analyses is change from baseline in follow-up visual field defect score (range, 0 to 20 units). In the Predictive Analysis, eyes with early average intraocular pressure greater than 17.5 mm Hg had an estimated worsening during subsequent follow-up that was 1 unit of visual field defect score greater than eyes with average intraocular pressure less than 14 mm Hg (P =.002). This amount of worsening was greater at 7 years (1.89 units; P <.001) than at 2 years (0.64 units; P =.071). In the Associative Analysis, eyes with 100% of visits with intraocular pressure less than 18 mm Hg over 6 years had mean changes from baseline in visual field defect score close to zero during follow-up, whereas eyes with less than 50% of visits with intraocular pressure less than 18 mm Hg had an estimated worsening over follow-up of 0.63 units of visual field defect score (P =.083). This amount of worsening was greater at 7 years (1.93 units; P <.001) than at 2 years (0.25 units; P =.572). In both analyses low intraocular pressure is associated with reduced

An Embedded Device for Real-Time Noninvasive Intracranial Pressure Estimation.

PubMed

Matthews, Jonathan M; Fanelli, Andrea; Heldt, Thomas

2018-01-01

The monitoring of intracranial pressure (ICP) is indicated for diagnosing and guiding therapy in many neurological conditions. Current monitoring methods, however, are highly invasive, limiting their use to the most critically ill patients only. Our goal is to develop and test an embedded device that performs all necessary mathematical operations in real-time for noninvasive ICP (nICP) estimation based on a previously developed model-based approach that uses cerebral blood flow velocity (CBFV) and arterial blood pressure (ABP) waveforms. The nICP estimation algorithm along with the required preprocessing steps were implemented on an NXP LPC4337 microcontroller unit (MCU). A prototype device using the MCU was also developed, complete with display, recording functionality, and peripheral interfaces for ABP and CBFV monitoring hardware. The device produces an estimate of mean ICP once per minute and performs the necessary computations in 410 ms, on average. Real-time nICP estimates differed from the original batch-mode MATLAB implementation of theestimation algorithm by 0.63 mmHg (root-mean-square error). We have demonstrated that real-time nICP estimation is possible on a microprocessor platform, which offers the advantages of low cost, small size, and product modularity over a general-purpose computer. These attributes take a step toward the goal of real-time nICP estimation at the patient's bedside in a variety of clinical settings.

Intraocular Pressure Response to Moderate Exercise during 30-Min Recovery.

PubMed

Najmanova, Eliska; Pluhacek, Frantisek; Botek, Michal

2016-03-01

The aim of the study was to evaluate intraocular pressure (IOP) before and after moderate exercise in normal healthy individuals with defined physical exertion. The second aim of this investigation was to determine the correlation between resting IOP (IOPr) and its change induced by exercise as well as the relationship between resting heart rate (HRr) and changes in IOP after exercise. Forty-one healthy volunteers between the ages of 19 and 25 years were recruited for the study. First, the resting (reference) values IOPr and HRr were measured after 30 min of resting time. Volunteers consequently performed 30 min of exercise on a bicycle ergometer. Intraocular pressure was remeasured immediately after the end of exercise (the relevant IOP change was denoted as ΔIOP0) and subsequently repeated 5, 10, 20, and 30 min after exercise. A significant decrease in IOP compared with the resting value (post hoc Tukey honest significant difference test) was found immediately after exercise (p = 2 × 10) and 5 and 10 min after exercise (p = 2 × 10 and p = 3 × 10). Significant relationships were found between the change in IOP (ΔIOP0) and baseline IOP (IOPr) and between the baseline resting heart rate (HRr) and the change in IOP (ΔIOP0). There was a significant IOP-lowering effect, which was persistent for 10 min after 30 min of exercise. The IOP change was dependent on the initial IOP reading and initial HR.

Intraocular Pressure Changes With Positioning During Laparoscopy

PubMed Central

Onakpoya, Oluwatoyin H.; Adenekan, Anthony T.; Awe, Oluwaseun. O.

2016-01-01

Background and Objectives: Pneumoperitoneum during laparoscopy can produce changes in intraocular pressure (IOP) that may be influenced by several factors. In this study, we investigated changes in IOP during laparoscopy with different positioning. Methods: We recruited adult patients without eye disease scheduled to undergo laparoscopic operation requiring a reverse Trendelenburg tilt (rTr; group A; n = 20) or Trendelenburg tilt (Tr; Group B; n = 20). IOP was measured at 7 time points (T1–T7). All procedures were performed with standardized anaesthetic protocol. Mean arterial pressure (MAP), heart rate (HR), peak and plateau airway pressure, and end-tidal carbon dioxide (ETCO2) measurements were taken at each time point. Results: Both groups were similar in age, sex, mean body mass index (BMI), duration of surgery, and preoperative IOP. A decrease in IOP was observed in both groups after induction of anaesthesia (T2), whereas induction of pneumoperitoneum produced a mild increase in IOP (T3) in both groups. The Trendelenburg tilt produced IOP elevations in 80% of patients compared to 45% after the reverse Trendelenburg tilt (P = .012). A significant IOP increase of 5 mm Hg or more was recorded in 3 (15%) patients in the Trendelenburg tilt group and in none in the reverse Trendelenburg group. At T7, IOP had returned to preoperative levels in all but 3 (15%) in the Trendelenburg and 1 (5%) in the reverse Trendelenburg group. Reversible changes were observed in the MAP, HR, ETCO2, and airway pressures in both groups. Conclusions: IOP changes induced by laparoscopy are realigned after evacuation of pneumoperitoneum. A Trendelenburg tilt however produced significant changes that may require careful patient monitoring during laparoscopic procedures. PMID:28028381

Peripapillary Schisis in Glaucoma Patients With Narrow Angles and Increased Intraocular Pressure

PubMed Central

Kahook, Malik Y.; Noecker, Robert J.; Ishikawa, Hiroshi; Wollstein, Gadi; Kagemann, Larry; Wojtkowski, Maciej; Duker, Jay S.; Srinivasan, Vivek J.; Fujimoto, James G.; Schuman, Joel S.

2007-01-01

PURPOSE To describe two cases of peripapillary retinal schisis in patients with glaucoma without evidence of optic nerve pits, pseudopits, or X-linked retinoschisis. DESIGN Two observational case reports and literature review. METHODS Imaging of the peripapillary nerve fiber layer and schisis cavities was completed in two patients, and one patient was followed over time. RESULTS The first patient, diagnosed with narrow angle glaucoma, was noted to have peripapillary schisis in the right eye with matching changes on visual field and optical coherence tomographic (OCT) results. Follow-up examination revealed that the schisis disappeared in the right eye while appearing in the left. The findings were verified with high-speed ultra-high-resolution OCT performed in both eyes. The second case involved a patient with anatomically narrow angles, high intraocular pressure (IOP), and peripapillary schisis extending into the macula. CONCLUSIONS Peripapillary retinoschisis may represent a unique sequelae of intraocular fluctuations in patients with uncontrolled glaucoma. Further studies are needed to better understand this disease process. PMID:17386284

Role of light and the circadian clock in the rhythmic oscillation of intraocular pressure: Studies in VPAC2 receptor and PACAP deficient mice.

PubMed

Fahrenkrug, Jan; Georg, Birgitte; Hannibal, Jens; Jørgensen, Henrik Løvendahl

2018-04-01

The intraocular pressure of mice displays a daily rhythmicity being highest during the dark period. The present study was performed to elucidate the role of the circadian clock and light in the diurnal and the circadian variations in intraocular pressure in mice, by using animals with disrupted clock function (VPAC2 receptor knockout mice) or impaired light information to the clock (PACAP knockout mice). In wildtype mice, intraocular pressure measured under light/dark conditions showed a statistically significant 24 h sinusoidal rhythm with nadir during the light phase and peak during the dark phase. After transfer of the wildtype mice into constant darkness, the intraocular pressure increased, but the rhythmic changes in intraocular pressure continued with a pattern identical to that obtained during the light/dark cycle. The intraocular pressure in VPAC2 receptor deficient mice during light/dark conditions also showed a sinusoidal pattern with significant changes as a function of a 24 h cycle. However, transfer of the VPAC2 receptor knockout mice into constant darkness completely abolished the rhythmic changes in intraocular pressure. The intraocular pressure in PACAP deficient mice oscillated significantly during both 24 h light and darkness and during constant darkness. During LD conditions, the amplitude of PACAP deficient was significantly lower compared to wildtype mice, resulting in higher daytime and lower nighttime values. In conclusion, by studying the VPAC2 receptor knockout mouse which lacks circadian control and the PACAP knockout mouse which displays impaired light signaling, we provided evidence that the daily intraocular pressure rhythms are primarily generated by the circadian master clock and to a lesser extent by environmental light and darkness. Copyright © 2018 Elsevier Ltd. All rights reserved.

Pigment dispersion and chronic intraocular pressure elevation after sulcus placement of 3-piece acrylic intraocular lens.

PubMed

Almond, M Camille; Wu, Michael C; Chen, Philip P

2009-12-01

A 55-year-old man had phacoemulsification and implantation of a 3-piece acrylic intraocular lens (IOL) (AcrySof MA60AC) in the right eye. One month postoperatively, the intraocular pressure (IOP) was 48 mm Hg and peripheral transillumination defects were noted in the iris circumferentially, with the IOL optic edge visible as a silhouette. Gonioscopy showed dense pigmentation of the trabecular meshwork in the right eye, but in the left eye, only mild trabecular meshwork pigment was seen, along with a concave peripheral iris insertion. At 21 months, the right eye required 3 medications for IOP control. While pigment dispersion has been widely reported after placement of 1-piece acrylic IOLs in the ciliary sulcus, we conclude that in susceptible individuals with a concave peripheral iris insertion, pigment dispersion can occur with sulcus placement of a 3-piece acrylic model despite its thinner optic and angulated haptics.

A chest drainage system with a real-time pressure monitoring device.

PubMed

Chen, Chih-Hao; Liu, Tsang-Pai; Chang, Ho; Huang, Tung-Sung; Liu, Hung-Chang; Chen, Chao-Hung

2015-07-01

Tube thoracostomy is a common procedure. A chest bottle may be used to both collect fluids and monitor the recovery of the chest condition. The presence of the "tidaling phenomenon" in the bottle can be reflective of the extent of patient's recovery. However, current practice essentially depends on gross observation of the bottle. The device used here is designed for a real-time monitoring of change in pleural pressure to allow clinicians to objectively determine when the lung has recovered, which is crucially important in order to judge when to remove the chest tube. The device is made of a pressure sensor with an operating range between -100 to +100 cmH2O and an amplifying using the "Wheatstone bridge" concept. Recording and analysis was performed with LABview software. The data can be shown in real-time on screen and also be checked retrospectively. The device was connected to the second part of a three-bottle drain system by a three-way connector. The test animals were two 40-kg pigs. We used a thoracoscopic procedure to create an artificial lung laceration with endoscopic scissors. Active air leaks could result in vigorous tidaling phenomenon up to 20 cmH2O. In the absence of gross tidaling phenomenon, the pressure changes were around 0.25 cmH2O. This real-time pleural pressure monitoring device can help clinicians objectively judge the extent of recovery of the chest condition. It can be used as an effective adjunct with the current chest drain system.

Dynamic changes of the intraocular pressure and the pressure of cerebrospinal fluid in nonglaucomatous neurological patients.

PubMed

González-Camarena, Pedro Iván; San-Juan, Daniel; González-Olhovich, Irene; Rodríguez-Arévalo, David; Lozano-Elizondo, David; Trenado, Carlos; Anschel, David J

2017-03-01

To describe the dynamic changes of the intraocular pressure (IOP) and intracranial pressure (ICP) with normal or pathological values (intracranial hypertension) in nonglaucomatous neurological patients during lumbar punction (LP). Case-control study, prospective measurement of tonometry in both groups referred for LP. Intraocular pressure, ICP and translaminar pressure difference (TPD) were compared pre- and post-LP. Thirty-six patients (72 eyes) with mean age of 38.5 (16-64) years and BMI of 26.81 kg/m 2 were analysed. The initial mean ICP was 12.81 (± 6.6) mmHg. The mean TPD before and after the LP was 1.48 mmHg and 0.65 mmHg, respectively. The mean IOP of both eyes decreased to 0.8 mmHg post-LP in patients with pathological ICP (p = 0.0193) and normal ICP (p = 0.006). We found a statistically significant decrease of the IOP post-LP compared to the pre-LP in both groups, being higher in patients with pathological ICP. There were no significant differences of the IOP in patients with normal versus pathological ICP pre-LP/post-LP; neither was found a correlation between ICP and IOP. © 2016 Acta Ophthalmologica Scandinavica Foundation. Published by John Wiley & Sons Ltd.

The Effect of Altitude on Intraocular Pressure in Vitrectomized Eyes with Sulfur Hexafluoride Tamponade by the Friedenwald Method: Rabbit Animal Model

PubMed Central

Fromow-Guerra, Jans; Solís-Vivanco, Adriana; Perez-Reguera, Adriana; Quiroz-Mercado, Hugo; Meza-de Regil, Armando; Papa-Oliva, Gabriela; Morales-Cantón, Virgilio

2016-01-01

The aim of this study is to assess the change in intraocular pressure after a road trip, in eyes with different levels of filling with gas tamponade. Five rabbit eyes were subject to pars plana vitrectomy and gas tamponade (filling percentage: 25%, 50%, and 100% of nonexpansile SF6, 100% saline solution, and 100% room air). A sixth eye was injected with 0.35 cc of undiluted SF6 without vitrectomy. Guided by global positioning system, they were driven to the highest point of the highway connecting Mexico City with Puebla city and back, stopping every 300 m to assess intraocular pressure. The rabbit's scleral rigidity and estimation for human eyes were done by using the Friedenwald nomogram. Maximum altitude was 3209 m (Δ949 m). There were significant differences in intraocular pressure on the rabbit eyes filled with SF6 at 100%, 50%, 25%, and 100% room air. Per every 100 m of altitude rise, the intraocular pressure increased by 1.53, 1.0046, 0.971, and 0.97 mmHg, respectively. Using the human Friedenwald rigidity coefficient, the human eye estimate for intraocular pressure change was 2.1, 1.8, 1.4, and 1.1 mmHg per every 100 m of attitude rise. Altitude changes have a significant impact on intraocular pressure. The final effect depends on the percentage of vitreous cavity fill and scleral rigidity. PMID:27957500

The Effect of Altitude on Intraocular Pressure in Vitrectomized Eyes with Sulfur Hexafluoride Tamponade by the Friedenwald Method: Rabbit Animal Model.

PubMed

Fromow-Guerra, Jans; Solís-Vivanco, Adriana; Velez-Montoya, Raul; Perez-Reguera, Adriana; Quiroz-Mercado, Hugo; Meza-de Regil, Armando; Papa-Oliva, Gabriela; Morales-Cantón, Virgilio

2016-01-01

The aim of this study is to assess the change in intraocular pressure after a road trip, in eyes with different levels of filling with gas tamponade. Five rabbit eyes were subject to pars plana vitrectomy and gas tamponade (filling percentage: 25%, 50%, and 100% of nonexpansile SF 6 , 100% saline solution, and 100% room air). A sixth eye was injected with 0.35 cc of undiluted SF 6 without vitrectomy. Guided by global positioning system, they were driven to the highest point of the highway connecting Mexico City with Puebla city and back, stopping every 300 m to assess intraocular pressure. The rabbit's scleral rigidity and estimation for human eyes were done by using the Friedenwald nomogram. Maximum altitude was 3209 m (Δ949 m). There were significant differences in intraocular pressure on the rabbit eyes filled with SF 6 at 100%, 50%, 25%, and 100% room air. Per every 100 m of altitude rise, the intraocular pressure increased by 1.53, 1.0046, 0.971, and 0.97 mmHg, respectively. Using the human Friedenwald rigidity coefficient, the human eye estimate for intraocular pressure change was 2.1, 1.8, 1.4, and 1.1 mmHg per every 100 m of attitude rise. Altitude changes have a significant impact on intraocular pressure. The final effect depends on the percentage of vitreous cavity fill and scleral rigidity.

Intraocular pressure measurements after conductive keratoplasty.

PubMed

Kymionis, George D; Naoumidi, Tatiana L; Aslanides, Ioannis M; Kumar, Vinod; Astyrakakis, Nikolaos I; Tsilimbaris, Miltiadis; Pallikaris, Ioannis G

2005-01-01

To determine the possible impact of conductive keratoplasty (CK) on intraocular pressure (IOP) measurements. A prospective, single-center, noncomparative interventional case series was performed. Baseline and postoperative IOPs were measured by Goldmann applanation tonometry in 32 eyes of 18 patients who underwent CK for hyperopia correction. Mean follow-up was 11.9 months (range: 8 to 18 months). After CK, a statistically significant decrease in the measured IOP was observed (before CK: 14.22+/-1.64 vs after CK: 12.66+/-2.21, P<.001). The change in IOP readings postoperatively was not correlated with age, sex, keratometric readings, or attempted correction. Despite the limitations due to the small number of patients enrolled in this study, the applanation tonometer appears to underestimate the true IOP after CK.

Corneal biomechanical parameters and intraocular pressure: the effect of topical anesthesia

PubMed Central

Ogbuehi, Kelechi C

2012-01-01

Background The intraocular pressures and biomechanical parameters measured by the ocular response analyzer make the analyzer a useful tool for the diagnosis and management of anterior segment disease. This observational study was designed to investigate the effect of topical anesthesia on the parameters measured by the ocular response analyzer: corneal hysteresis, corneal resistance factor, Goldmann-correlated intraocular pressure (IOPg), and corneal-compensated intraocular pressure (IOPcc). Methods Two sets of measurements were made for 78 eyes of 39 subjects, approximately 1 week apart. In session 1, each eye of each subject was randomized into one of three groups: polyvinyl alcohol (0.5%), tetracaine hydrochloride (0.5%), or oxybuprocaine hydrochloride (0.4%). In session 2, eyes that were in the polyvinyl alcohol group in session 1 were assigned to the tetracaine group, those in the tetracaine group in session 1 were assigned to oxybuprocaine group, and those in the oxybuprocaine group in session 1 were assigned to the polyvinyl alcohol group. For both sessions, each subject first had his or her central corneal thickness assessed with a specular microscope, followed by measurements of intraocular pressure and corneal biomechanical parameters with the Ocular Response Analyzer. All measurements were repeated for 2 minutes and 5 minutes following the instillation of either polyvinyl alcohol, tetracaine, or oxybuprocaine. The level of statistical significance was 0.05. Results Polyvinyl alcohol, tetracaine hydrochloride, and oxybuprocaine hydrochloride had no statistically significant (P > 0.05) effect on any of the biomechanical parameters of the cornea. There was no statistically significant effect on either IOPg (P > 0.05) or IOPcc (P > 0.05) 2 minutes after the eye drops were instilled in either session. Five minutes after the eye drops were instilled, polyvinyl alcohol showed no statistically significant effect on either IOPg (P > 0.05) or IOPcc (P > 0.05) in

Corneal biomechanical parameters and intraocular pressure: the effect of topical anesthesia.

PubMed

Ogbuehi, Kelechi C

2012-01-01

The intraocular pressures and biomechanical parameters measured by the ocular response analyzer make the analyzer a useful tool for the diagnosis and management of anterior segment disease. This observational study was designed to investigate the effect of topical anesthesia on the parameters measured by the ocular response analyzer: corneal hysteresis, corneal resistance factor, Goldmann-correlated intraocular pressure (IOPg), and corneal-compensated intraocular pressure (IOPcc). Two sets of measurements were made for 78 eyes of 39 subjects, approximately 1 week apart. In session 1, each eye of each subject was randomized into one of three groups: polyvinyl alcohol (0.5%), tetracaine hydrochloride (0.5%), or oxybuprocaine hydrochloride (0.4%). In session 2, eyes that were in the polyvinyl alcohol group in session 1 were assigned to the tetracaine group, those in the tetracaine group in session 1 were assigned to oxybuprocaine group, and those in the oxybuprocaine group in session 1 were assigned to the polyvinyl alcohol group. For both sessions, each subject first had his or her central corneal thickness assessed with a specular microscope, followed by measurements of intraocular pressure and corneal biomechanical parameters with the Ocular Response Analyzer. All measurements were repeated for 2 minutes and 5 minutes following the instillation of either polyvinyl alcohol, tetracaine, or oxybuprocaine. The level of statistical significance was 0.05. Polyvinyl alcohol, tetracaine hydrochloride, and oxybuprocaine hydrochloride had no statistically significant (P > 0.05) effect on any of the biomechanical parameters of the cornea. There was no statistically significant effect on either IOPg (P > 0.05) or IOPcc (P > 0.05) 2 minutes after the eye drops were instilled in either session. Five minutes after the eye drops were instilled, polyvinyl alcohol showed no statistically significant effect on either IOPg (P > 0.05) or IOPcc (P > 0.05) in either session

A chest drainage system with a real-time pressure monitoring device

PubMed Central

Liu, Tsang-Pai; Huang, Tung-Sung; Liu, Hung-Chang; Chen, Chao-Hung

2015-01-01

Background Tube thoracostomy is a common procedure. A chest bottle may be used to both collect fluids and monitor the recovery of the chest condition. The presence of the “tidaling phenomenon” in the bottle can be reflective of the extent of patient’s recovery. Objectives However, current practice essentially depends on gross observation of the bottle. The device used here is designed for a real-time monitoring of change in pleural pressure to allow clinicians to objectively determine when the lung has recovered, which is crucially important in order to judge when to remove the chest tube. Methods The device is made of a pressure sensor with an operating range between −100 to +100 cmH2O and an amplifying using the “Wheatstone bridge” concept. Recording and analysis was performed with LABview software. The data can be shown in real-time on screen and also be checked retrospectively. The device was connected to the second part of a three-bottle drain system by a three-way connector. Results The test animals were two 40-kg pigs. We used a thoracoscopic procedure to create an artificial lung laceration with endoscopic scissors. Active air leaks could result in vigorous tidaling phenomenon up to 20 cmH2O. In the absence of gross tidaling phenomenon, the pressure changes were around 0.25 cmH2O. Conclusions This real-time pleural pressure monitoring device can help clinicians objectively judge the extent of recovery of the chest condition. It can be used as an effective adjunct with the current chest drain system. PMID:26380726

Changes in choroidal thickness following trabeculectomy and its correlation with the decline in intraocular pressure.

PubMed

Silva, Diana; Lopes, Ana Sofia; Henriques, Susana; Lisboa, Maria; Pinto, Sara; Trancoso Vaz, Fernando; Prieto, Isabel

2018-04-16

Evaluate whether there are significant changes in choroidal thickness following trabeculectomy, and how they relate do the decline in intraocular pressure. This was a prospective evaluation of 28 eyes who underwent Moorfields modified trabeculectomy. The choroidal thickness was measured via OCT with enhanced depth imaging, before surgery and 1 day, 1 week and 1 month after surgery. Measurements were taken at the fovea, 1000 µm temporal to the fovea and 1000 µm nasal to the fovea. The relationship between choroidal thickness and intraocular pressure was statistically evaluated. The mean intraocular pressure before surgery was 25.07 ± 4.64 mmHg; 8.57 ± 3.62 mmHg after 1 day; 10.36 ± 4.39 mmHg after 1 week and 13.71 ± 5.13 mmHg after 1 month. Mean choroidal thickness increased after trabeculectomy with maximal values at 1 week. The largest increase was found at the fovea, with an average before surgery of 253.54 ± 62.01 µm; 286.75 ± 64.20 µm at 1 day, 286.36 ± 63.14 µm at 1 week and 271.00 ± 60.31 µm at 1 month. Increase in choroidal thickness was significant 1 day and 1 week after surgery in the foveal (p = 0.012, p = 0.007) and temporal (p = 0.040, p = 0.000) locations and 1 week postoperatively on the nasal location (p = 0.016). None of them were significant at 1 month after surgery. Preoperative IOP and choroidal thickness were correlated at all macular locations (ρ = 0.449-0.525, p = 0.004-0.016) yet no correlation was found between increase in choroidal thickness and decline in intraocular pressure in the postoperative period. Choroidal thickness appears to increase temporarily after trabeculectomy and these changes were not correlated with the decline in intraocular pressure. Further research is required to fully understand this phenomenon.

The impact of ocular hemodynamics and intracranial pressure on intraocular pressure during acute gravitational changes.

PubMed

Nelson, Emily S; Mulugeta, Lealem; Feola, Andrew; Raykin, Julia; Myers, Jerry G; Samuels, Brian C; Ethier, C Ross

2017-08-01

Exposure to microgravity causes a bulk fluid shift toward the head, with concomitant changes in blood volume/pressure, and intraocular pressure (IOP). These and other factors, such as intracranial pressure (ICP) changes, are suspected to be involved in the degradation of visual function and ocular anatomical changes exhibited by some astronauts. This is a significant health concern. Here, we describe a lumped-parameter numerical model to simulate volume/pressure alterations in the eye during gravitational changes. The model includes the effects of blood and aqueous humor dynamics, ICP, and IOP-dependent ocular compliance. It is formulated as a series of coupled differential equations and was validated against four existing data sets on parabolic flight, body inversion, and head-down tilt (HDT). The model accurately predicted acute IOP changes in parabolic flight and HDT, and was satisfactory for the more extreme case of inversion. The short-term response to the changing gravitational field was dominated by ocular blood pressures and compliance, while longer-term responses were more dependent on aqueous humor dynamics. ICP had a negligible effect on acute IOP changes. This relatively simple numerical model shows promising predictive capability. To extend the model to more chronic conditions, additional data on longer-term autoregulation of blood and aqueous humor dynamics are needed. NEW & NOTEWORTHY A significant percentage of astronauts present anatomical changes in the posterior eye tissues after spaceflight. Hypothesized increases in ocular blood volume and intracranial pressure (ICP) in space have been considered to be likely factors. In this work, we provide a novel numerical model of the eye that incorporates ocular hemodynamics, gravitational forces, and ICP changes. We find that changes in ocular hemodynamics govern the response of intraocular pressure during acute gravitational change. Copyright © 2017 the American Physiological Society.

Cataract, phacoemulsification and intraocular pressure: Is the anterior segment anatomy the missing piece of the puzzle?

PubMed

Masis Solano, Marisse; Lin, Shan C

2018-01-29

Cataract extraction is a safe and effective surgery that has a lowering effect on the intraocular pressure. The specific mechanisms for this effect are still unclear. A direct inflammatory effect on the trabecular meshwork, alteration of the blood aqueous barrier, changes in the ciliary body and mechanical changes of the anterior segment anatomy are the key to understand cataract surgery and it's effects on aqueous humor dynamics. Additionally, with the advent of AS OCT, changes in the anterior segment of the eye have been studied and several parameters (such as lens vault, angle opening distance and anterior chamber depth) have been identified as predictors of intraocular pressure change. In eyes with narrow angles there is a greater drop in intraocular pressure after cataract surgery and it is correlated with parameters related to anterior chamber space. It is safe to affirm that cataract surgery is an important part of the modern glaucoma treatment and evidence should be analyzed as part of a bigger picture in order to more accurately understand its clinical relevance. Copyright © 2018. Published by Elsevier Ltd.

LONG-TERM INTRAOCULAR PRESSURE AFTER UNCOMPLICATED PARS PLANA VITRECTOMY FOR IDIOPATHIC EPIRETINAL MEMBRANE.

PubMed

Tognetto, Daniele; Pastore, Marco R; Cirigliano, Gabriella; DʼAloisio, Rossella; Borelli, Massimo; De Giacinto, Chiara

2017-11-16

To investigate long-term intraocular pressure trends after uncomplicated pars plana vitrectomy for idiopathic epiretinal membrane. Three hundred and sixty-eight eyes of 368 consecutive patients were enrolled. Changes in intraocular pressure 1, 3, 6, and 12 months after surgery and during the final follow-up visit were evaluated in vitrectomized eyes and nonvitrectomized fellow eyes. The median follow-up period was 36 months (range 12-92 months). Longitudinal data analysis evidenced a 2.5-mmHg (2.2 mmHg; 2.7 mmHg, 95% confidence interval) statistically significant difference in intraocular pressure 30 days after surgery between treated and fellow untreated eyes, gradually recovering to a not significant 0.2-mmHg (-0.1 mmHg; 0.4 mmHg, 95% confidence interval) difference within 26 months. The incidence of late-onset ocular hypertension was 5.7% (21 over 347, 2%; 12%, 95% confidence interval) without difference between the treated eyes and the group control. No significant difference in the incidence of late-onset ocular hypertension and sex, lens status, or gauge of vitrectomy instruments was detected. Only patient's age was significantly higher (mean difference 4.2 years; 0.1-8.0 years, Monte Carlo, 95% confidence interval) in those who developed late-onset ocular hypertension in the vitrectomized eye. Uncomplicated pars plana vitrectomy for idiopathic epiretinal membrane seems not to increase the risk of late-onset ocular hypertension or open-angle glaucoma development.

Effect of oral administration of carprofen on intraocular pressure in normal dogs.

PubMed

Meekins, J M; Overton, T L; Rankin, A J; Roush, J K

2016-08-01

The aim of this study was to determine the effect of oral administration of carprofen on intraocular pressure in normal dogs. Twelve young adult beagle dogs were randomly assigned to treatment (n = 6) or control (n = 6) groups. After an 11-day acclimation period, the treatment group received approximately 2.2 mg/kg carprofen per os every 12 h for 7 days, and the control group received a placebo gel capsule containing no drug per os every 12 h for 7 days. Intraocular pressure (IOP) was measured by a rebound tonometer at three time points per day (8 am, 2 pm, and 8 pm) during the acclimation (days 1-11) and treatment (days 12-18) phases and for 48 h (days 19-20) after the completion of treatment. There was no statistically significant change in IOP for either eye in the dogs receiving oral carprofen during the treatment phase (days 12-18). After day 4, no significant daily IOP changes were seen in control group dogs. Carprofen administered orally every 12 h for 7 days had no effect on IOP in normal beagle dogs. An acclimation period to frequent IOP measurements of at least 5 days is necessary to establish baseline IOP values and minimize possible anxiety-related effects on IOP measurements. © 2016 John Wiley & Sons Ltd.

Incidence of Intraocular Pressure Elevation following Intravitreal Ranibizumab (Lucentis) for Age-related Macular Degeneration.

PubMed

Reis, Gustavo Msm; Grigg, John; Chua, Brian; Lee, Anne; Lim, Ridia; Higgins, Ralph; Martins, Alessandra; Goldberg, Ivan; Clement, Colin I

2017-01-01

The aim of this article is to evaluate the rate of patients developing sustained elevated intraocular pressure (IOP) after ranibizumab (Lucentis) intravitreal (IVT) injections. This is a retrospective study. Charts of 192 consecutive patients receiving Lucentis for age-related macular degeneration (AMD) were retrospectively reviewed. We enrolled patients with at least two IOP measurements between injections. Elevated IOP was defined as >21 mm Hg with an increase of at least 20% from baseline. Noninjected contralateral eyes of the same patient cohort were used as control. Primary outcome was defined as elevated IOP. Secondary outcomes were presence and type of glaucoma, number of injections, and time to IOP elevation. Elevated IOP occurred at a significantly higher rate in eyes receiving IVT ranibizumab (7.47%; n = 9) compared with control (0.93%; n = 1). Patients with preexisting glaucoma or ocular hypertension (OHT) were more likely to develop elevated IOP after IVT ranibizumab injection. Intravitreal ranibizumab injections are associated with sustained IOP elevation in some eyes. Reis GMSM, Grigg J, Chua B, Lee A, Lim R, Higgins R, Martins A, Goldberg I, Clement CI. The Incidence of Intraocular Pressure Elevation following Intravitreal Ranibizumab (Lucentis) for Age-related Macular Degeneration. J Curr Glaucoma Pract 2017;11(1):3-7.

STS-44 crewmembers conduct DSO 472, Intraocular Pressure, on OV-104's middeck

NASA Image and Video Library

1991-12-01

STS044-04-001 (24 Nov-1 Dec 1991) --- Astronauts F. Story Musgrave (right) and Mario Runco, Jr., mission specialists, team up for one of the biomedical Detailed Supplementary Objective (DSO) test on the eight-day flight, this one involving intraocular pressure.

Real-Time Smart Textile-Based System to Monitor Pressure Offloading of Diabetic Foot Ulcers.

PubMed

Raviglione, Andrea; Reif, Roberto; Macagno, Maurizio; Vigano, Davide; Schram, Justin; Armstrong, David

2017-09-01

The lifetime risk of developing a diabetic foot ulcer (DFU) is at least 25%. A DFU carries a 50% risk for infection and at least 20% of those receive some form of amputation. The most significant parameter that prevents or delays ulcer healing is high plantar pressure. To improve the patient's healing process, the DFU's plantar pressure should remain cumulatively low. Therefore, a tool that continuously measures the DFU loading, and provides real-time feedback can improve the healing outcome. We report the development of a system capable of continuously measuring the pressure, which could have applications to monitor DFU. The system contains a textile pressure sensor attached to a stretchable band, hardware that collects data and transmits them via Bluetooth to a phone, an app that gathers the data and stores them in the cloud, and a web dashboard that displays the data to the clinician. The sensor was characterized in vitro using the system, and the web-dashboard was developed and tested on simulated patient data. We demonstrate the feasibility of developing the system and characterize the pressure response of the device. As a result, we demonstrate a viable method for monitoring DFU off-loading in real time. The presented study demonstrates the feasibility to develop a simple, modular wearable system that opens up new possibilities for diabetic foot ulcer care by providing a way of monitoring the pressure under the ulcer in real time.

Effects of hyperbaric exposure on eyes with intraocular gas bubbles.

PubMed

Jackman, S V; Thompson, J T

1995-01-01

Air travel is known to be potentially hazardous for patients with intraocular gas bubbles, and the external pressure changes associated with hyperbaric oxygen therapy and scuba diving could be similarly dangerous. Rabbits with a perfluoropropane/air gas mixture filling approximately 60% of the vitreous cavity of the right eye were exposed to 3 different hyperbaric pressure profiles to an equivalent depth of 33 feet. The first group were a control group and were not exposed to hyperbaric pressures. The second group remained at an equivalent depth of 33 feet for 30 minutes, and the third group remained at 33 feet for 1 minute. Both groups ascended to normal atmospheric pressure at a rate of 1 foot per minute. The fourth group remained at 33 feet for 1 minute and then ascended at a rate of 0.2 feet per minute. In all eyes with an intraocular gas bubble, intraocular pressure dropped to zero when the atmospheric pressure was increased, and rose to more than 50 mmHg when the atmospheric pressure was returned to normal. Pressures in excess of 50 mmHg were sustained for 10 minutes or longer in each rabbit exposed to one of the hyperbaric profiles. No significant intraocular pressure changes were observed in eyes without an intraocular gas bubble or eyes not exposed to hyperbaric pressure. Marked elevation in intraocular pressure occurs as a result of hyperbaric exposure in eyes with an intraocular gas bubble. Hyperbaric exposure is therefore not advisable for patients with intraocular gas bubbles.

Intraocular pressure variation following retrobulbar anaesthesia among the different sex, age and ethnic groups in Malaysia.

PubMed

Lee, F N; Kong, V Y; Lee, G P; Ho, K H; Choon, S C; Hoh, H B

1999-12-01

A total of 114 patients (48 Chinese, 34 Malay and 32 Indian) undergoing extracapsular cataract extraction (ECCE) with intraocular lens implantation, were enrolled. All were given 3 ml of local anaesthetic (combination of equal amounts of lignocaine 2% and bupivacaine 0.5%) using retrobulbar technique. Intraocular pressure (IOP) was measured at different time intervals; before, immediately after and 5 minutes after injection with Honan balloon compression. Mean IOP increased by 5.0 mmHg immediately after injection (p < 0.001) and reduced to baseline level after 5 minutes of external compression. Although there were no statistical difference in terms of IOP variation between sex and age groups, Chinese patients demonstrated the highest IOP rise following retrobulbar anaesthesia. This is the first study to demonstrate the influence of race in the IOP response with Chinese subjects having the highest IOP rise.

Genome-wide association study of intraocular pressure identifies the GLCCI1/ICA1 region as a glaucoma susceptibility locus

PubMed Central

Strange, Amy; Bellenguez, Céline; Sim, Xueling; Luben, Robert; Hysi, Pirro G.; Ramdas, Wishal D.; van Koolwijk, Leonieke M.E.; Freeman, Colin; Pirinen, Matti; Su, Zhan; Band, Gavin; Pearson, Richard; Vukcevic, Damjan; Langford, Cordelia; Deloukas, Panos; Hunt, Sarah; Gray, Emma; Dronov, Serge; Potter, Simon C.; Tashakkori-Ghanbaria, Avazeh; Edkins, Sarah; Bumpstead, Suzannah J.; Blackwell, Jenefer M.; Bramon, Elvira; Brown, Matthew A.; Casas, Juan P.; Corvin, Aiden; Duncanson, Audrey; Jankowski, Janusz A.Z.; Markus, Hugh S.; Mathew, Christopher G.; Palmer, Colin N.A.; Plomin, Robert; Rautanen, Anna; Sawcer, Stephen J.; Trembath, Richard C.; Wood, Nicholas W.; Barroso, Ines; Peltonen, Leena; Healey, Paul; McGuffin, Peter; Topouzis, Fotis; Klaver, Caroline C.W.; van Duijn, Cornelia M.; Mackey, David A.; Young, Terri L.; Hammond, Christopher J.; Khaw, Kay-Tee; Wareham, Nick; Wang, Jie Jin; Wong, Tien Y.; Foster, Paul J.; Mitchell, Paul; Spencer, Chris C.A.; Donnelly, Peter; Viswanathan, Ananth C.

2013-01-01

To discover quantitative trait loci for intraocular pressure, a major risk factor for glaucoma and the only modifiable one, we performed a genome-wide association study on a discovery cohort of 2175 individuals from Sydney, Australia. We found a novel association between intraocular pressure and a common variant at 7p21 near to GLCCI1 and ICA1. The findings in this region were confirmed through two UK replication cohorts totalling 4866 individuals (rs59072263, Pcombined = 1.10 × 10−8). A copy of the G allele at this SNP is associated with an increase in mean IOP of 0.45 mmHg (95%CI = 0.30–0.61 mmHg). These results lend support to the implication of vesicle trafficking and glucocorticoid inducibility pathways in the determination of intraocular pressure and in the pathogenesis of primary open-angle glaucoma. PMID:23836780

Early aggressive intraocular pressure lowering, target intraocular pressure, and a novel concept for glaucoma care.

PubMed

Singh, Kuldev; Shrivastava, Anurag

2008-11-01

Early diagnosis of glaucomatous optic nerve damage offers the potential for early treatment which may prevent vision loss from this neurodegenerative disease. Even in patients who do not begin early treatment, early diagnosis allows for better monitoring of disease at a stage where the stakes are lower relative to later stages of the disease. For these reasons, early diagnosis of glaucomatous optic nerve disease is desirable and opens the door for appropriately aggressive therapy. The target intraocular pressure (IOP) concept is widely employed by glaucoma practitioners. Although there have been no randomized clinical trials or other high-quality studies showing the benefits of setting a target IOP versus not using this approach, there is ample evidence that lowering IOP slows glaucoma progression and, in general, lower is better, regardless of disease stage and baseline IOP level. We propose an alternative approach to managing glaucoma without the use of the target IOP concept and suggest that this market IOP concept should be compared with the target IOP approach in an appropriately powered comparative clinical trial.

Combined ab interno trabeculotomy and lens extraction: a novel management option for combined uveitic and chronic narrow angle raised intraocular pressure

PubMed Central

Lin, Siying; Gupta, Bhaskar; Rossiter, Jonathan

2016-01-01

Minimally invasive glaucoma surgery is a developing area that has the potential to replace traditional glaucoma surgery, with its known risk profile, but at present there are no randomised controlled data to validate its use. We report on a case where sequential bilateral combined ab interno trabeculotomy and lens extraction surgery was performed on a 45-year-old woman with combined uveitic and chronic narrow angle raised intraocular pressure. Maximal medical management alone could not control the intraocular pressure. At 12-month follow-up, the patient had achieved stable intraocular pressure in both eyes on a combination of topical ocular antiglaucomatous and steroid therapies. This case demonstrates the effectiveness of trabecular meshwork ablation via ab interno trabeculotomy in a case of complex mixed mechanism glaucoma. PMID:26833953

Eye retraction and rotation during Corvis ST 'air puff' intraocular pressure measurement and its quantitative analysis.

PubMed

Boszczyk, Agnieszka; Kasprzak, Henryk; Jóźwik, Agnieszka

2017-05-01

The aim of this study was to analyse the indentation and deformation of the corneal surface, as well as eye retraction, which occur during air puff intraocular pressure (IOP) measurement. A group of 10 subjects was examined using a non-contact Corvis ST tonometer, which records image sequences of corneas deformed by an air puff. Obtained images were processed numerically in order to extract information about corneal deformation, indentation and eyeball retraction. The time dependency of the apex deformation/eye retraction ratio and the curve of dependency between apex indentation and eye retraction take characteristic shapes for individual subjects. It was noticed that the eye globes tend to rotate towards the nose in response to the air blast during measurement. This means that the eye globe not only displaces but also rotates during retraction. Some new parameters describing the shape of this curve are introduced. Our data show that intraocular pressure and amplitude of corneal indentation are inversely related (r 8  = -0.83, P = 0.0029), but the correlation between intraocular pressure and amplitude of eye retraction is low and not significant (r 8  = -0.24, P = 0.51). The curves describing corneal behaviour during air puff tonometry were determined and show that the eye globe rotates towards the nose during measurement. In addition, eye retraction amplitudes may be related to elastic or viscoelastic properties of deeper structures in the eye or behind the eye and this should be further investigated. Many of the proposed new parameters present comparable or even higher repeatability than the standard parameters provided by the Corvis ST. © 2017 The Authors Ophthalmic & Physiological Optics © 2017 The College of Optometrists.

Assessment of Intraocular and Systemic Vasculature Pressure Parameters in Simulated Microgravity with Thigh Cuff Countermeasure

NASA Technical Reports Server (NTRS)

Huang, Alex S.; Balasubramanian, Siva; Tepelus, Tudor; Sadda, Jaya; Sadda, Srinivas; Stenger, Michael B.; Lee, Stuart M. C.; Laurie, Steve S.; Liu, John; Macias, Brandon R.

2017-01-01

Changes in vision have been well documented among astronauts during and after long-duration space flight. One hypothesis is that the space flight induced headward fluid alters posterior ocular pressure and volume and may contribute to visual acuity decrements. Therefore, we evaluated venoconstrictive thigh cuffs as a potential countermeasure to the headward fluid shift-induced effects on intraocular pressure (IOP) and cephalic vascular pressure and volumes.

Real-Time Optical Monitoring of Flow Kinetics and Gas Phase Reactions Under High-Pressure OMCVD Conditions

NASA Technical Reports Server (NTRS)

Dietz, N.; McCall, S.; Bachmann, K. J.

2001-01-01

This contribution addresses the real-time optical characterization of gas flow and gas phase reactions as they play a crucial role for chemical vapor phase depositions utilizing elevated and high pressure chemical vapor deposition (HPCVD) conditions. The objectives of these experiments are to validate on the basis of results on real-time optical diagnostics process models simulation codes, and provide input parameter sets needed for analysis and control of chemical vapor deposition at elevated pressures. Access to microgravity is required to retain high pressure conditions of laminar flow, which is essential for successful acquisition and interpretation of the optical data. In this contribution, we describe the design and construction of the HPCVD system, which include access ports for various optical methods of real-time process monitoring and to analyze the initial stages of heteroepitaxy and steady-state growth in the different pressure ranges. To analyze the onset of turbulence, provisions are made for implementation of experimental methods for in-situ characterization of the nature of flow. This knowledge will be the basis for the design definition of experiments under microgravity, where gas flow conditions, gas phase and surface chemistry, might be analyzed by remote controlled real-time diagnostics tools, developed in this research project.

Effect of latanoprost/timolol and dorzolamide/tiomolol on intraocular pressure after phacoemulsification surgery

PubMed Central

Erdogan, Haydar; Ozec, Ayse Vural; Caner, Cengiz; Toker, Mustafa Ilker; Arici, Mustafa Kemal; Topalkara, Aysen

2011-01-01

AIM To evalaute the effect of fixed-combination latanoprost 0.005%/timolol maleate 0.5% and dorzolamide hydrochloride 2%/timolol maleate 0.5% on postoperative intraocular pressure after phacoemulsification cataract surgery. METHODS This study is a prospective, randomized, double-masked and placebo-controlled. The study included 90 eyes of 90 patients which were scheduled to have phacoemulsification surgery. Patients were randomly assigned preoperatively to 1 of 3 groups (30 eyes of 30 patients). Two hour before surgery, the patients received one drop latanoprost/timolol (group 1), dorzolamide/timolol (group 2) and placebo (group 3, control group). The IOPs were measured at preoperative and postoperative 4, 8, and 24 hours. RESULTS The preoperative mean intraocular pressure was not statistically significant between both drug groups and control group. In group 1 and 2, the postoperative mean IOP [group1: (14.03±3.15)mmHg and group 2: (14.16±4.43)mmHg] at 24 hours were significantly lower than the control group [(16.93±3.70)mmHg, (P<0.05)]. In addition, the postoperative mean IOP of group 1 [(14.90±3.69)mmHg] at 8 hours was significantly lower than the control group [(17.70±3.89)mmHg, (P<0.05)], but there was no significant difference between group 2 [(16.16±5.23)mmHg] and control group at 8 hours (P>0.05). CONCLUSION When compared with placebo, the use of preoperative fixed combination of latanoprost/timolol and dorzolamide/timolol is an effective method for preventing intraocular pressure elevation in 24 hours after phacoemulsification surgery, but did not completely prevent IOP spikes. PMID:22553640

The synthetic cannabinoid WIN55212-2 decreases the intraocular pressure in human glaucoma resistant to conventional therapies.

PubMed

Porcella, A; Maxia, C; Gessa, G L; Pani, L

2001-01-01

The search for new ocular hypotensive agents represents a frontier of current eye research because blindness due to optic neuropathy occurs insidiously in 10% of all patients affected by glaucoma. Cannabinoids have been proposed to lower intraocular pressure by either central or peripheral effects but a specific mechanism for this action has never been elucidated. We recently demonstrated the presence of the central cannabinoid receptor (CB(1)) mRNA and protein in the human ciliary body. In the present study we show that the synthetic CB(1) receptor agonist, WIN 55212--2, applied topically at doses of 25 or 50 microg (n = 8), decreases the intraocular pressure of human glaucoma resistant to conventional therapies within the first 30 min (15 +/- 0.5% and 23 +/- 0.9%, respectively). A maximal reduction of 20 +/- 0.7% and 31 +/- 0.6%, respectively, is reached in the first 60 min. These data confirm that CB(1) receptors have direct involvement in the regulation of human intraocular pressure, and suggest that, among various classes of promising antiglaucoma agents, synthetic CB(1) receptor agonists should deserve further research and clinical development.

Influence of corneal thickness on the intraocular pressure readings for Maklakoff's tonometer of different weight

NASA Astrophysics Data System (ADS)

Franus, D. V.

2018-05-01

Research is conducted into variation in the stress-strain state of the corneoscleral shell of the human eye under loading by a flat base stamp of varying weight. A three-dimensional finite-element model of the contact problem of loading of the corneoscleral shell in the ANSYS program package is presented. Cornea and sclera are modeled as conjugated transversely isotropic spherical shells. The cornea is modeled as a multilayer shell with variable thickness in which all modeled layers have their own individual elastic properties. The research deals with the numerical calculation of the diameter of the contact zone between the shell and the stamp. Values of correction coefficients for intraocular pressure are obtained depending on the thickness of the corneal shell in its center, allowing the true intraocular pressure to be determined more accurately.

Combined ab interno trabeculotomy and lens extraction: a novel management option for combined uveitic and chronic narrow angle raised intraocular pressure.

PubMed

Lin, Siying; Gupta, Bhaskar; Rossiter, Jonathan

2016-02-01

Minimally invasive glaucoma surgery is a developing area that has the potential to replace traditional glaucoma surgery, with its known risk profile, but at present there are no randomised controlled data to validate its use. We report on a case where sequential bilateral combined ab interno trabeculotomy and lens extraction surgery was performed on a 45-year-old woman with combined uveitic and chronic narrow angle raised intraocular pressure. Maximal medical management alone could not control the intraocular pressure. At 12-month follow-up, the patient had achieved stable intraocular pressure in both eyes on a combination of topical ocular antiglaucomatous and steroid therapies. This case demonstrates the effectiveness of trabecular meshwork ablation via ab interno trabeculotomy in a case of complex mixed mechanism glaucoma. 2016 BMJ Publishing Group Ltd.

Intra-Ocular Pressure Measurement in a Patient with a Thin, Thick or Abnormal Cornea.

PubMed

Clement, Colin I; Parker, Douglas G A; Goldberg, Ivan

2016-01-01

Accurate measurement of intra-ocular pressure is a fundamental component of the ocular examination. The most common method of measuring IOP is by Goldmann applanation tonometry, the accuracy of which is influenced by the thickness and biomechanical properties of the cornea. Algorithms devised to correct for corneal thickness to estimate IOP oversimplify the effects of corneal biomechanics. The viscous and elastic properties of the cornea influence IOP measurements in unpredictable ways, a finding borne out in studies of patients with inherently abnormal and surgically altered corneal biomechanics. Dynamic contour tonometry, rebound tonometry and the ocular response analyzer provide useful alternatives to GAT in patients with abnormal corneas, such as those who have undergone laser vision correction or keratoplasty. This article reviews the various methods of intra-ocular pressure measurement available to the clinician and the ways in which their utility is influenced by variations in corneal thickness and biomechanics.

Incidence, Risk Factors, and Timing of Elevated Intraocular Pressure After Intravitreal Triamcinolone Acetonide Injection for Macular Edema Secondary to Retinal Vein Occlusion: SCORE Study Report 15.

PubMed

Aref, Ahmad A; Scott, Ingrid U; Oden, Neal L; Ip, Michael S; Blodi, Barbara A; VanVeldhuisen, Paul C

2015-09-01

The Standard of Care vs Corticosteroid for Retinal Vein Occlusion (SCORE) Study showed that intravitreal triamcinolone acetonide (IVTA) is effective at reducing macular edema and improving visual acuity in participants with retinal vein occlusion. Secondary analysis of the incidence, risk factors, and timing of intraocular pressure (IOP) elevation occurring after IVTA provides guidance for clinical decision making and management of patients treated with IVTA. To investigate the incidence, risk factors, and time course of IOP elevation in participants in the SCORE Study. Secondary analysis conducted from August through December 2014 of a prospective, randomized clinical trial featuring an evaluable population conducted at 75 clinical sites. Six hundred eighty-two patients with macular edema secondary to retinal vein occlusion were enrolled in the study. The SCORE Study enrollment period ran from November 4, 2004, to February 29, 2008, with participant follow-up ending February 28, 2009. Study participants were randomized to standard of care, 1 mg of IVTA, or 4 mg of IVTA therapy and followed up for a mean (SD) of 24.7 (10.3) months. Intraocular pressure elevation greater than 10 mm Hg from baseline. Kaplan-Meier incidences of IOP elevation greater than 10 mm Hg from baseline at 36 months were 0.02 (95% CI, 0.01-0.06), 0.09 (95% CI, 0.05-0.14), and 0.45 (95% CI, 0.38-0.53) in the standard of care, 1-mg IVTA, and 4-mg IVTA groups, respectively. The rates of IOP-related events were higher for the 4-mg IVTA group compared with the other groups (P ≤ .001 for main outcome measure). Younger age, 4-mg IVTA vs 1-mg IVTA treatment, and higher baseline IOP were found to confer greater risk for IOP-related events (P < .05 for all). The median number of days from time of first injection to IOP elevation greater than 10 mm Hg from baseline was 34.0 and 52.5 days in participants treated with 1-mg and 4-mg IVTA, respectively. Intravitreal triamcinolone acetonide injection

The vascular basis of the positional influence of the intraocular pressure.

PubMed

Krieglstein, G K; Waller, W K; Leydhecker, W

1978-05-02

By measuring intraocular pressure in different body positions from 60 degrees semiupright to 30 degrees head down, a nonlinear relationship between IOP increase and body position was confirmed. IOP postural response in individual subjects was roughly correlated to ophthalmic arterial pressure and to the episcleral venous pressure postural response. In one series of subjects, the episcleral venous pressure increments due to posture wa; parallel to the applanation-indentation disparity in the same individual eyes. Differential tonometry with applanation or indentation procedures under blind conditions gave significantly low indentation readings. It is concluded that IOP postural response depends on arterial and venous vascular changes when subjects move from an erect to a horizontal body position. Blood expulsion from the choroid by indentation tonometry might be the reason that this tonometric procedure does not measure IOP changes based on vascular changes.

Intraocular pressure in the smallest primate aging model: the gray mouse lemur.

PubMed

Dubicanac, Marko; Joly, Marine; Strüve, Julia; Nolte, Ingo; Mestre-Francés, Nadine; Verdier, Jean-Michel; Zimmermann, Elke

2018-05-01

The aim of this study was to assess the practicability of common tonometers used in veterinary medicine for rapid intraocular pressure (IOP) screening, to calibrate IOP values gained by the tonometers, and to define a reference IOP value for the healthy eye in a new primate model for aging research, the gray mouse lemur. TonoVet ® and the TonoPen ™ measurements were calibrated manometrically in healthy enucleated eyes of mouse lemurs euthanized for veterinary reasons. For comparison of the practicability of both tonometers as a rapid IOP assessment tool for living mouse lemurs, the IOP of 24 eyes of 12 animals held in the hand was measured. To define a standard reference value for IOP in mouse lemurs, 258 healthy animals were measured using the TonoVet ® . Intraocular pressure measurements for the TonoVet ® can be corrected using the formula: y = 0.981 + (1.962*TonoVet ® value), and those for the TonoPen ™ using that of y = 5.38 + (1.426*TonoPen ™ value). The calibrated IOP for a healthy mouse lemur eye was 20.3 ± 2.8 mmHg. The TonoVet ® showed advantages in practicability, for example, small corneal contact area, short and painless corneal contact, shortened total time spent on investigation, as well as the more accurate measured values. IOP measurements of healthy mouse lemur eyes were not affected by age, sex, eye side, or colony. Tonometry using TonoVet ® is the more practicable assessment tool for IOP measurement of the tiny eyes of living mouse lemurs. Pathological deviations can be identified based on the described reference value. © 2016 American College of Veterinary Ophthalmologists.

Short-Term Moderately Elevated Intraocular Pressure Is Associated With Elevated Scotopic Electroretinogram Responses

PubMed Central

Choh, Vivian; Gurdita, Akshay; Tan, Bingyao; Prasad, Ratna C.; Bizheva, Kostadinka; Joos, Karen M.

2016-01-01

Purpose Moderately elevated intraocular pressure (IOP) is a risk factor for open-angle glaucoma. Some patients suffer glaucoma despite clinically measured normal IOPs. Fluctuations in IOP may have a significant role since IOPs are higher during sleep and inversion activities. Controlled transient elevations of IOPs in rats over time lead to optic nerve structural changes that are similar to the early changes observed in constant chronic models of glaucoma. Because early intervention decreases glaucoma progression, this study was done to determine if early physiological changes to the retina could be detected with noninvasive electrophysiological and optical imaging tests during moderately elevated IOP. Methods Intraocular pressures were raised to moderately high levels (35 mm Hg) in one eye of Sprague-Dawley rats while the other (control) eye was untreated. One group of rats underwent scotopic threshold response (STR) and electroretinogram (ERG) testing, while another 3 groups underwent optical coherence tomography (OCT) imaging, Western blot, or histologic evaluation. Results The amplitudes of the STR and ERG responses in eyes with moderately elevated IOPs were enhanced compared to the values before IOP elevation, and compared to untreated contralateral eyes. Structural changes to the optic nerve also occurred during IOP elevation. Conclusions Although ischemic IOP elevations are well-known to globally reduce components of the scotopic ERG, acute elevation in rats to levels often observed in untreated glaucoma patients caused an increase in these parameters. Further exploration of these phenomena may be helpful in better understanding the mechanisms mediating early retinal changes during fluctuating or chronically elevated IOP. PMID:27100161

Real-time Optical Coherence Tomography Incorporated in the Operating Microscope during Cataract Surgery.

PubMed

Almutlak, Mohammed A; Aloniazan, Turki; May, William

2017-01-01

A 55-year-old male presented with reduced vision due to senile cataract. The patient consented to undergo real-time intraoperative anterior segment-optical coherence tomography (AS-OCT) during phacoemulsification with intraocular lens (IOL) implantation. Images were captured at various points during the surgery. The use of AS-OCT incorporated into the surgical microscope was evaluated as an adjunct to cataract surgery. We were able to successfully evaluate, in real-time, wound architecture, the attachment of Descemet's membrane, the posterior capsule, and IOL position. Real-time AS-OCT can be used to proactively address potential complications and verify IOL placement intraoperatively.

Diurnal Alterations of Refraction, Anterior Segment Biometrics, and Intraocular Pressure in Long-Time Dehydration due to Religious Fasting.

PubMed

Baser, Gonen; Cengiz, Hakan; Uyar, Murat; Seker Un, Emine

2016-01-01

To investigate the effects of dehydration due to fasting on diurnal changes of intraocular pressure, anterior segment biometrics, and refraction. The intraocular pressures, anterior segment biometrics (axial length: AL; Central corneal thickness: CCT; Lens thickness: LT; Anterior chamber depth: ACD), and refractive measurements of 30 eyes of 15 fasting healthy male volunteers were recorded at 8:00 in the morning and 17:00 in the evening in the Ramadan of 2013 and two months later. The results were compared and the statistical analyses were performed using the Rstudio software version 0.98.501. The variables were investigated using visual (histograms, probability plots) and analytical methods (Kolmogorov-Smirnov/Shapiro-Wilk test) to determine whether or not they were normally distributed. The refractive values remained stable in the fasting as well as in the control period (p = 0.384). The axial length measured slightly shorter in the fasting period (p = 0.001). The corneal thickness presented a diurnal variation, in which the cornea measured thinner in the evening. The difference between the fasting and control period was not statistically significant (p = 0.359). The major differences were observed in the anterior chamber depth and IOP. The ACD was shallower in the evening during the fasting period, where it was deeper in the control period. The diurnal IOP difference was greater in the fasting period than the control period. Both were statistically significant (p = 0.001). The LT remained unchanged in both periods. The major difference was shown in the anterior chamber shallowing in the evening hours and IOP. Our study contributes the hypothesis that the posterior segment of the eye is more responsible for the axial length alterations and normovolemia has a more dominant influence on diurnal IOP changes.

Intraocular pressure, ultrasonographic and echobiometric findings of juvenile Yacare caiman (Caiman yacare) eye.

PubMed

Ruiz, Thaís; Campos, Wilma N S; Peres, Thalita P S; Gonçalves, Gentil F; Ferraz, Rosa H S; Néspoli, Pedro E B; Sousa, Valéria R F; Ribeiro, Alexandre P

2015-01-01

The aim was to determine the intraocular pressure (IOP), the ultrasonographic and echobiometric findings in the eyes of juvenile Yacare caiman (Caiman yacare). Twenty-two healthy caimans from a breeding farm in Brazilian Pantanal. Intraocular pressure was measured under physical restraint and topical anesthesia by applanation tonometry. Five individual measurements of each eye were recorded by the same examiner. B-mode ultrasonography was performed with a 10-MHz linear transducer, and the anterior chamber depth, lens thickness, vitreous depth, and axial globe length were measured. Unpaired and paired t-tests were used to assess data. Pearson's test was used to assess correlations between IOP and ocular structures (P < 0.05). Mean ± SD IOP of the 44 eyes studied was 9.56 ± 2.69 mmHg, (range 5.4-15.6 mmHg). IOP did not differ significantly between right and left eyes or between genders (P > 0.05). Echobiometric measurements did not differ significantly between eyes and genders (P > 0.05). Intraocular structures measured in male and female subjects were, respectively, 2.61 ± 0.13 and 2.55 ± 0.18 mm for anterior chamber depth, 7.60 ± 0.17 and 7.54 ± 0.20 mm for lens thickness, 6.83 ± 0.20 and 6.90 ± 0.22 mm for vitreous chamber depth, and 17.55 ± 0.25 and 17.54 ± 0.29 mm for axial globe length. Correlations were not observed (P > 0.05). Reference values of tonometry and distances of intraocular structures of Yacare caiman were described. IOP did not correlate with echobiometric measurements in this crocodilian. The ultrasonographic appearance was similar to other domestic and wild species. © 2014 American College of Veterinary Ophthalmologists.

A real-time plantar pressure feedback device for foot unloading.

PubMed

Femery, Virginie G; Moretto, Pierre G; Hespel, Jean-Michel G; Thévenon, André; Lensel, Ghislaine

2004-10-01

To develop and test a plantar pressure control device that provides both visual and auditory feedback and is suitable for correcting plantar pressure distribution patterns in persons susceptible to neuropathic foot ulceration. Pilot test. Sports medicine laboratory in a university in France. One healthy man in his mid thirties. Not applicable. Main outcome measures A device was developed based on real-time feedback, incorporating an acoustic alarm and visual signals, adjusted to a specific pressure load. Plantar pressure measured during walking, at 6 sensor locations over 27 steps under 2 different conditions: (1) natural and (2) unloaded in response to device feedback. The subject was able to modify his gait in response to the auditory and visual signals. He did not compensate for the decrease of peak pressure under the first metarsal by increasing the duration of the load shift under this area. Gait pattern modification centered on a mediolateral load shift. The auditory signal provided a warning system alerting the user to potentially harmful plantar pressures. The visual signal warned of the degree of pressure. People who have lost nociceptive perception, as in cases of diabetic neuropathy, may be able to change their walking pattern in response to the feedback provided by this device. The visual may have diagnostic value in determining plantar pressures in such patients. This pilot test indicates that further studies are warranted.

Intracranial and Intraocular Pressure at the Lamina Cribrosa: Gradient Effects.

PubMed

Jóhannesson, Gauti; Eklund, Anders; Lindén, Christina

2018-04-12

A pressure difference between the intraocular and intracranial compartments at the site of the lamina cribrosa has been hypothesized to have a pathophysiological role in several optic nerve head diseases. This paper reviews the current literature on the translamina cribrosa pressure difference (TLCPD), the associated pressure gradient, and its potential pathophysiological role, as well as the methodology to assess TLCPD. For normal-tension glaucoma (NTG), initial studies indicated low intracranial pressure (ICP) while recent findings indicate that a reduced ICP is not mandatory. Data from studies on the elevated TLCPD as a pathophysiological factor of NTG are equivocal. From the identification of potential postural effects on the cerebrospinal fluid (CSF) communication between the intracranial and retrolaminar space, we hypothesize that the missing link could be a dysfunction of an occlusion mechanism of the optic nerve sheath around the optic nerve. In upright posture, this could cause an elevated TLCPD even with normal ICP and we suggest that this should be investigated as a pathophysiological component in NTG patients.

Reduced pressure for fewer pressure ulcers: can real-time feedback of interface pressure optimise repositioning in bed?

PubMed

Gunningberg, Lena; Carli, Cheryl

2016-10-01

The aim of this study was to (i) describe registered nurses' and assistant nurses' repositioning skills with regard to their existing attitudes to and theoretical knowledge of pressure ulcer (PU) prevention, and (ii) evaluate if the continuous bedside pressure mapping (CBPM) system provides staff with a pedagogic tool to optimise repositioning. A quantitative study was performed using a descriptive, comparative design. Registered nurses (n = 19) and assistant nurses (n = 33) worked in pairs, and were instructed to place two volunteers (aged over 70 years) in the best pressure-reducing position (lateral and supine), first without viewing the CBPM monitor and then again after feedback. In total, 240 positionings were conducted. The results show that for the same person with the same available pressure-reducing equipment, the peak pressure varied considerably between nursing pairs. Reducing pressure in the lateral position appeared to be the most challenging. Peak pressures were significantly reduced, based on visual feedback from the CBPM monitor. The number of preventive interventions also increased, as well as patients' comfort. For the nurses as a group, the knowledge score was 59·7% and the attitude score was 88·8%. Real-time visual feedback of pressure points appears to provide another dimension to complement decision making with respect to PU prevention. © 2014 The Authors. International Wound Journal © 2014 Medicalhelplines.com Inc and John Wiley & Sons Ltd.

Baseline Intraocular Pressure Is Associated with Subjective Sensitivity to Physical Exertion in Young Males

ERIC Educational Resources Information Center

Vera, Jesús; Jiménez, Raimundo; García, José Antonio; Perales, José Cesar; Cárdenas, David

2018-01-01

Purpose: The purposes of this study were to (a) investigate the effect of physical effort (cycling for 60 min at 60 ± 5% of individually computed reserve heart-rate capacity), combined with 2 different levels of cognitive demand (2-back, oddball), on intraocular pressure (IOP) and subjective judgments of perceived exertion (ratings of perceived…

Infusion-line pressure as a real-time monitor of convection-enhanced delivery in pre-clinical models.

PubMed

Lam, Miu Fei; Foo, Stacy W L; Thomas, Meghan G; Lind, Christopher R P

2014-01-15

Acute convection-enhanced delivery (CED) is a neurosurgical delivery technique that allows for precise and uniform distribution of an infusate to a brain structure. It remains experimental due to difficulties in ensuring successful delivery. Real-time monitoring is able to provide immediate feedback on cannula placement, infusate distribution, and if the infusion is proceeding as planned or is failing due to reflux or catheter obstruction. Pressure gradient is the driving force behind CED, with the infusion pressure being directly proportional to the flow-rate. The aim of this study was to assess the feasibility of using infusion-line pressure profiling to distinguish in real-time between succeeding and failing CED infusions. To do so we delivered cresyl violet dye at 0.5, 1.0 and 2.0 μl/min via CED in vitro using 0.6% agarose gel and in vivo to the rat striatum. Infusions that failed in agarose gel models could only be differentiated late during the procedures. In the rat in vivo model, the infusion-line profiles of obstructed infusions were not distinctive from those of successful infusions. Intraoperative magnetic resonance imaging (MRI) is used for real-time visualisation of cannula placement and infusate distribution. Particularly for animal pre-clinical work, it would be advantageous to supplement MRI with a cheap, accessible technique to monitor infusions and provide a real-time measure of infusion success or failure. Infusion-line pressure monitoring was of limited value in identifying successful CED with small volume infusions, whilst its utility for large volume infusion remains unknown. Crown Copyright © 2013. Published by Elsevier B.V. All rights reserved.

An SSME High Pressure Oxidizer Turbopump diagnostic system using G2 real-time expert system

NASA Technical Reports Server (NTRS)

Guo, Ten-Huei

1991-01-01

An expert system which diagnoses various seal leakage faults in the High Pressure Oxidizer Turbopump of the SSME was developed using G2 real-time expert system. Three major functions of the software were implemented: model-based data generation, real-time expert system reasoning, and real-time input/output communication. This system is proposed as one module of a complete diagnostic system for the SSME. Diagnosis of a fault is defined as the determination of its type, severity, and likelihood. Since fault diagnosis is often accomplished through the use of heuristic human knowledge, an expert system based approach has been adopted as a paradigm to develop this diagnostic system. To implement this approach, a software shell which can be easily programmed to emulate the human decision process, the G2 Real-Time Expert System, was selected. Lessons learned from this implementation are discussed.

Immediate effect of intravitreal injection of bevacizumab on intraocular pressure

PubMed Central

Lemos-Reis, Ricardo; Moreira-Gonçalves, Nuno; Melo, António B; Carneiro, Ângela M; Falcão-Reis, Fernando M

2014-01-01

Purpose To investigate the immediate effect of intravitreal injection of bevacizumab on intraocular pressure (IOP). Methods This was a prospective and nonrandomized study. A total of 291 eyes with macular edema or active choroidal neovascularization were submitted to a single 1.25 mg (0.05 mL) bevacizumab intravitreal injection. Intraocular pressure was measured with an Icare® tonometer immediately before and after injection in a seated position. The presence of subconjunctival reflux was recorded. The fellow eye served as the control. Results Mean preoperative IOP was 18.0±5.9 mmHg in the treated eye versus 16.9±6.0 mmHg in the fellow eye. Mean postoperative IOP was 42.1±14.5 mmHg in the treated eye versus 17.5±6.0 mmHg in the fellow eye. The IOP variation was statistically significant in both cases and controls (P<0.001 and P=0.003, respectively), and this increase was higher in cases than in controls (P<0.001). Postoperative IOPs higher than 50 mmHg were achieved in 32.0% of the eyes. Subconjunctival reflux was present in 21.3% and determined a lower IOP rise (P<0.001). Tested variables (glaucoma, phakic status, and sex) did not have a statistically significant effect on IOP rise or subconjunctival reflux. Conclusion IOP increases with intravitreal bevacizumab injection, reaching 50 mmHg or more in about one third of patients. A higher IOP is expected if no subconjunctival reflux occurs. The baseline IOP does not influence the incidence of subconjunctival reflux. The clinical relevance of these facts has yet to be clarified. PMID:25092962

Repeat sample intraocular pressure variance in induced and naturally ocular hypertensive monkeys.

PubMed

Dawson, William W; Dawson, Judyth C; Hope, George M; Brooks, Dennis E; Percicot, Christine L

2005-12-01

To compare repeat-sample means variance of laser induced ocular hypertension (OH) in rhesus monkeys with the repeat-sample mean variance of natural OH in age-range matched monkeys of similar and dissimilar pedigrees. Multiple monocular, retrospective, intraocular pressure (IOP) measures were recorded repeatedly during a short sampling interval (SSI, 1-5 months) and a long sampling interval (LSI, 6-36 months). There were 5-13 eyes in each SSI and LSI subgroup. Each interval contained subgroups from the Florida with natural hypertension (NHT), induced hypertension (IHT1) Florida monkeys, unrelated (Strasbourg, France) induced hypertensives (IHT2), and Florida age-range matched controls (C). Repeat-sample individual variance means and related IOPs were analyzed by a parametric analysis of variance (ANOV) and results compared to non-parametric Kruskal-Wallis ANOV. As designed, all group intraocular pressure distributions were significantly different (P < or = 0.009) except for the two (Florida/Strasbourg) induced OH groups. A parametric 2 x 4 design ANOV for mean variance showed large significant effects due to treatment group and sampling interval. Similar results were produced by the nonparametric ANOV. Induced OH sample variance (LSI) was 43x the natural OH sample variance-mean. The same relationship for the SSI was 12x. Laser induced ocular hypertension in rhesus monkeys produces large IOP repeat-sample variance mean results compared to controls and natural OH.

Circadian intraocular pressure rhythms in athletic horses under different lighting regime.

PubMed

Bertolucci, Cristiano; Giudice, Elisabetta; Fazio, Francesco; Piccione, Giuseppe

2009-02-01

The present study was undertaken to investigate the existence of intraocular pressure (IOP) rhythms in athletic thoroughbred horses maintained under a 24 h cycle of light and darkness (LD) or under constant light (LL) or constant dark (DD) conditions. We identified an IOP circadian rhythm that is entrained to the 24 h LD cycle. IOP was low during the dark phase and high during the light phase, with a peak at the end of the light phase (ZT10). The circadian rhythm of IOP persisted in DD (with a peak at CT9.5), demonstrating an endogenous component in IOP rhythm. As previously shown in other mammalian species, horse IOP circadian rhythmicity was abolished in LL. Because tonometry is performed in horses for the diagnosis of ophthalmologic diseases, such as glaucoma or anterior uveitis, the daily variation in IOP must be taken into account in clinical practice to properly time tests and to interpret clinical findings.

Baroreceptors mask sympathetic responses to high intraocular pressure in dogs.

PubMed

Yahagi, Toru; Koyama, Shozo; Osaka, Kazumasa; Koyama, Haruhide

2008-05-30

These experiments were designed to investigate whether increasing intraocular pressure (IOP) in anesthetized dogs produces differential control of sympathetic nerve activities to various organs (heart, kidney, liver, and spleen) and if these sympathetic responses are modified by baroreceptors. We performed simultaneous multi-recordings of cardiac, renal, hepatic and splenic sympathetic nerve activities (CNA, RNA, HNA and SpNA, respectively) during 2 min of increasing IOP to a mean pressure of 30 mmHg. After increasing IOP in dogs with the intact baroreceptors, all of measured nerve activities did not change significantly throughout the experiment. In dogs with denervation of baroreceptors (cervical vagotomy with denervation of the carotid sinus and aortic nerves), only RNA and CNA showed significant increases in response to the increased IOP. However, time course changes in HNA and SpNA did not show any significant differences as compared with the baseline or that of the control group. These results indicate that systemic sympathetic nerve responses to increasing IOP are masked by systemic baroreceptors. As animals were denervated of their systemic baroreceptors, the unidirectional sympathoexcitatory responses to increased IOP were observed on CNA and RNA, but not on HNA and SpNA. These sympathetic outflow, when systemic baroreceptors are impaired as observed in old age, may play an important role in management of glaucoma attack with the use of adrenolytic drugs.

Effect of Topical Calcium Channel Blockers on Intraocular Pressure in Steroid-induced Glaucoma.

PubMed

Ganekal, Sunil; Dorairaj, Syril; Jhanji, Vishal; Kudlu, Krishnaprasad

2014-01-01

To evaluate the effect of 0.125% verapamil and 0.5% diltiazem eye drops on intraocular pressure (IOP) in steroid-induced glaucoma in rabbit eyes. A total of 18 rabbits with steroid-induced glaucoma were divided into three groups (A, B and C; n = 6 each). Right eyes in groups A, B and C received 0.5% diltiazem, 0.125% verapamil and 0.5% timolol eye drops twice daily for 12 days, respectively; whereas, left eyes received distilled water. IOP was measured with Tono-pen XL at baseline, day 4, day 8, and day 12 of treatment. Both 0.5% diltiazem and 0.125% verapamil eye drops significantly reduced IOP compared to control eyes (p < 0.05). Reduction of IOP by 0.5% diltiazem, 0.125% verapamil eye drops were comparable to 0.5% timolol. No surface toxicity or systemic side effects were noted during the study period. Calcium channel blockers, verapamil, and diltia-zem significantly reduced IOP in rabbiteyes. This group of drugs may have a potential role in treatment of glaucoma How to cite this article: Ganekal S, Dorairaj S, Jhanji V, Kudlu K. Effect of Topical Calcium Channel Blockers on Intraocular Pressure in Steroid-induced Glaucoma. J Current Glau Prac 2014;8(1):15-19.

Esophagogastric Junction pressure morphology: comparison between a station pull-through and real-time 3D-HRM representation.

PubMed

Nicodème, F; Lin, Z; Pandolfino, J E; Kahrilas, P J

2013-09-01

Esophagogastric junction (EGJ) competence is the fundamental defense against reflux making it of great clinical significance. However, characterizing EGJ competence with conventional manometric methodologies has been confounded by its anatomic and physiological complexity. Recent technological advances in miniaturization and electronics have led to the development of a novel device that may overcome these challenges. Nine volunteer subjects were studied with a novel 3D-HRM device providing 7.5 mm axial and 45° radial pressure resolution within the EGJ. Real-time measurements were made at rest and compared to simulations of a conventional pull-through made with the same device. Moreover, 3D-HRM recordings were analyzed to differentiate contributing pressure signals within the EGJ attributable to lower esophageal sphincter (LES), diaphragm, and vasculature. 3D-HRM recordings suggested that sphincter length assessed by a pull-through method greatly exaggerated the estimate of LES length by failing to discriminate among circumferential contractile pressure and asymmetric extrinsic pressure signals attributable to diaphragmatic and vascular structures. Real-time 3D EGJ recordings found that the dominant constituents of EGJ pressure at rest were attributable to the diaphragm. 3D-HRM permits real-time recording of EGJ pressure morphology facilitating analysis of the EGJ constituents responsible for its function as a reflux barrier making it a promising tool in the study of GERD pathophysiology. The enhanced axial and radial recording resolution of the device should facilitate further studies to explore perturbations in the physiological constituents of EGJ pressure in health and disease. © 2013 John Wiley & Sons Ltd.

21 CFR 886.4270 - Intraocular gas.

Code of Federal Regulations, 2010 CFR

2010-04-01

... DEVICES OPHTHALMIC DEVICES Surgical Devices § 886.4270 Intraocular gas. (a) Identification. An intraocular gas is a device consisting of a gaseous fluid intended to be introduced into the eye to place pressure... required. As of May 28, 1976, an approval under section 515 of the act is required before this device may...

Real time pressure signal system for a rotary engine

NASA Technical Reports Server (NTRS)

Rice, W. J. (Inventor)

1984-01-01

A real-time IMEP signal which is a composite of those produced in any one chamber of a three-lobed rotary engine is developed by processing the signals of four transducers positioned in a Wankel engine housing such that the rotor overlaps two of the transducers for a brief period during each cycle. During the overlap period of any two transducers, their output is compared and sampled for 10 microseconds per 0.18 degree of rotation by a sampling switch and capacitive circuit. When the switch is closed, the instantaneous difference between the value of the transducer signals is provided while with the switch open the average difference is produced. This combined signal, along with the original signal of the second transducer, is fed through a multiplexer to a pressure output terminal. Timing circuits, controlled by a crank angle encoder on the engine, determine which compared transducer signals are applied to the output terminal and when, as well as the open and closed periods of the switches.

Real-Time Detection of Dust Devils from Pressure Readings

NASA Technical Reports Server (NTRS)

Wagstaff, Kiri

2009-01-01

A method for real-time detection of dust devils at a given location is based on identifying the abrupt, temporary decreases in atmospheric pressure that are characteristic of dust devils as they travel through that location. The method was conceived for use in a study of dust devils on the Martian surface, where bandwidth limitations encourage the transmission of only those blocks of data that are most likely to contain information about features of interest, such as dust devils. The method, which is a form of intelligent data compression, could readily be adapted to use for the same purpose in scientific investigation of dust devils on Earth. In this method, the readings of an atmospheric- pressure sensor are repeatedly digitized, recorded, and processed by an algorithm that looks for extreme deviations from a continually updated model of the current pressure environment. The question in formulating the algorithm is how to model current normal observations and what minimum magnitude deviation can be considered sufficiently anomalous as to indicate the presence of a dust devil. There is no single, simple answer to this question: any answer necessarily entails a compromise between false detections and misses. For the original Mars application, the answer was sought through analysis of sliding time windows of digitized pressure readings. Windows of 5-, 10-, and 15-minute durations were considered. The windows were advanced in increments of 30 seconds. Increments of other sizes can also be used, but computational cost increases as the increment decreases and analysis is performed more frequently. Pressure models were defined using a polynomial fit to the data within the windows. For example, the figure depicts pressure readings from a 10-minute window wherein the model was defined by a third-degree polynomial fit to the readings and dust devils were identified as negative deviations larger than both 3 standard deviations (from the mean) and 0.05 mbar in magnitude. An

Intraocular Pressure, Tear Production, and Ocular Echobiometry in Guinea Pigs (Cavia porcellus)

PubMed Central

Rajaei, Seyed Mehdi; Mood, Maneli Ansari; Sadjadi, Reza; Azizi, Farzaneh

2016-01-01

The purpose of this study was to evaluate intraocular pressure (IOP) by means of rebound tonometry, to assess tear production by using the endodontic absorbent paper point tear test (EAPTT) and phenol red thread test (PRTT), and to determine the effects of time of day on IOP and tear production in guinea pigs. The study population comprised 24 healthy adult guinea pigs (12 male, 12 female; 48 eyes) of different breeds and ranging in age from 12 to 15 mo. IOP and tear production were measured at 3 time points (0700, 1500, and 2300) during a 24-h period. Overall values (mean ± 1 SD) were: IOP, 6.81 ± 1.41 mm Hg (range, 4.83 to 8.50); PRTT, 14.33 ± 1.35 mm (range, 12.50 to 16.83); and EAPTT, 8.54 ± 1.08 mm (range, 7.17 to 10.0 mm). In addition, ultrasound biometry was performed by using a B-mode system with linear 8-MHz transducer. This study reports reference values for IOP and tear production in guinea pigs. PMID:27423156

Regulation of intraocular pressure in mice: structural analysis of dopaminergic and serotonergic systems in response to cabergoline.

PubMed

Platania, Chiara Bianca Maria; Leggio, Gian Marco; Drago, Filippo; Salomone, Salvatore; Bucolo, Claudio

2013-11-01

Elevated intraocular pressure (IOP) is the main recognized risk factor of glaucoma. To investigate the contribution of dopaminergic and serotonergic systems in IOP regulation, we used cabergoline, a mixed dopamine and serotonin agonist, in C57BL/6J WT and dopamine D₃ receptor knock-out (D₃R⁻/⁻) mice with normal eye pressure or steroid-induced ocular hypertension. Furthermore, we studied the structural basis of the cabergoline-mediated activation of the dopaminergic and serotonergic systems by molecular modeling. Topical application of cabergoline, significantly decreased, in a dose-dependent manner, the intraocular pressure in WT mice, both in an ocular normotensive group (-9, -5 and -2 mmHg with 5%, 1%, and 0.1%, respectively) and an ocular hypertensive group, with a prolonged effect in this latter group. No change of intraocular pressure was observed after topical application of cabergoline in D₃R⁻/⁻ mice. We modeled and optimized, with molecular dynamics, structures of hD₃, h5HT(1A) and h5HT(2A-C) receptors; thereafter we carried out molecular docking of cabergoline. Docking revealed that binding of cabergoline into D₃ and 5HT(1A) receptors is associated with a better desolvation energy in comparison to 5HT(2A-C) binding. In conclusion, the present study support the hypothesis that dopaminergic system is pivotal to regulate IOP and that D₃R represents an intriguing target in the treatment of glaucoma. Furthermore, the structure-based computational approach adopted in this study is able to build and refine structure models of homologous dopaminergic and serotonergic receptors that may be of interest for structure-based drug discovery of ligands, with dopaminergic selectivity or with multi-pharmacological profile, potentially useful to treat optic neuropathies. Copyright © 2013 Elsevier Inc. All rights reserved.

Personalized modeling for real-time pressure ulcer prevention in sitting posture.

PubMed

Luboz, Vincent; Bailet, Mathieu; Boichon Grivot, Christelle; Rochette, Michel; Diot, Bruno; Bucki, Marek; Payan, Yohan

2018-02-01

Ischial pressure ulcer is an important risk for every paraplegic person and a major public health issue. Pressure ulcers appear following excessive compression of buttock's soft tissues by bony structures, and particularly in ischial and sacral bones. Current prevention techniques are mainly based on daily skin inspection to spot red patches or injuries. Nevertheless, most pressure ulcers occur internally and are difficult to detect early. Estimating internal strains within soft tissues could help to evaluate the risk of pressure ulcer. A subject-specific biomechanical model could be used to assess internal strains from measured skin surface pressures. However, a realistic 3D non-linear Finite Element buttock model, with different layers of tissue materials for skin, fat and muscles, requires somewhere between minutes and hours to compute, therefore forbidding its use in a real-time daily prevention context. In this article, we propose to optimize these computations by using a reduced order modeling technique (ROM) based on proper orthogonal decompositions of the pressure and strain fields coupled with a machine learning method. ROM allows strains to be evaluated inside the model interactively (i.e. in less than a second) for any pressure field measured below the buttocks. In our case, with only 19 modes of variation of pressure patterns, an error divergence of one percent is observed compared to the full scale simulation for evaluating the strain field. This reduced model could therefore be the first step towards interactive pressure ulcer prevention in a daily set-up. Copyright © 2017 Tissue Viability Society. Published by Elsevier Ltd. All rights reserved.

Note: A micro-perfusion system for use during real-time physiological studies under high pressure

NASA Astrophysics Data System (ADS)

Maltas, Jeff; Long, Zac; Huff, Alison; Maloney, Ryan; Ryan, Jordan; Urayama, Paul

2014-10-01

We construct a micro-perfusion system using piston screw pump generators for use during real-time, high-pressure physiological studies. Perfusion is achieved using two generators, with one generator being compressed while the other is retracted, thus maintaining pressurization while producing fluid flow. We demonstrate control over perfusion rates in the 10-μl/s range and the ability to change between fluid reservoirs at up to 50 MPa. We validate the screw-pump approach by monitoring the cyanide-induced response of UV-excited autofluorescence from Saccharomyces cerevisiae under pressurization.

Note: A micro-perfusion system for use during real-time physiological studies under high pressure.

PubMed

Maltas, Jeff; Long, Zac; Huff, Alison; Maloney, Ryan; Ryan, Jordan; Urayama, Paul

2014-10-01

We construct a micro-perfusion system using piston screw pump generators for use during real-time, high-pressure physiological studies. Perfusion is achieved using two generators, with one generator being compressed while the other is retracted, thus maintaining pressurization while producing fluid flow. We demonstrate control over perfusion rates in the 10-μl/s range and the ability to change between fluid reservoirs at up to 50 MPa. We validate the screw-pump approach by monitoring the cyanide-induced response of UV-excited autofluorescence from Saccharomyces cerevisiae under pressurization.

Payload and Components Real-Time Automated Test System (PACRATS), Data Acquisition of Leak Rate and Pressure Data Test Procedure

NASA Technical Reports Server (NTRS)

Rinehart, Maegan L.

2011-01-01

The purpose of this activity is to provide the Mechanical Components Test Facility (MCTF) with the capability to obtain electronic leak test and proof pressure data, Payload and Components Real-time Automated Test System (PACRATS) data acquisition software will be utilized to display real-time data. It will record leak rates and pressure/vacuum level(s) simultaneously. This added functionality will provide electronic leak test and pressure data at specified sampling frequencies. Electronically stored data will provide ES61 with increased data security, analysis, and accuracy. The tasks performed in this procedure are to verify PACRATS only, and are not intended to provide verifications for MCTF equipment.

Can we trust intraocular pressure measurements in eyes with intracameral air?

PubMed

Jóhannesson, Gauti; Lindén, Christina; Eklund, Anders; Behndig, Anders; Hallberg, Per

2014-10-01

To evaluate the effect of intracameral air on intraocular pressure (IOP) measurements using Goldmann applanation tonometry (GAT) and applanation resonance tonometry (ART) in an in-vitro porcine eye model. IOP was measured on thirteen freshly enucleated eyes at three reference pressures: 20, 30, and 40 mmHg. Six measurements/method were performed in a standardized order with GAT and ART respectively. Air was injected intracamerally in the same manner as during Descemet's stripping endothelial keratoplasty (DSEK) and Descemet's membrane endothelial keratoplasty (DMEK), and the measurements were repeated. Measured IOP increased significantly for both tonometry methods after air injection: 0.7 ± 2.1 mmHg for GAT and 10.6 ± 4.9 mmHg for ART. This difference was significant at each reference pressure for ART but not for GAT. Although slightly affected, this study suggests that we can trust GAT IOP-measurements in eyes with intracameral air, such as after DSEK/DMEK operations. Ultrasound-based methods such as ART should not be used.

An SSME high pressure oxidizer turbopump diagnostic system using G2(TM) real-time expert system

NASA Technical Reports Server (NTRS)

Guo, Ten-Huei

1991-01-01

An expert system which diagnoses various seal leakage faults in the High Pressure Oxidizer Turbopump of the SSME was developed using G2(TM) real-time expert system. Three major functions of the software were implemented: model-based data generation, real-time expert system reasoning, and real-time input/output communication. This system is proposed as one module of a complete diagnostic system for Space Shuttle Main Engine. Diagnosis of a fault is defined as the determination of its type, severity, and likelihood. Since fault diagnosis is often accomplished through the use of heuristic human knowledge, an expert system based approach was adopted as a paradigm to develop this diagnostic system. To implement this approach, a software shell which can be easily programmed to emulate the human decision process, the G2 Real-Time Expert System, was selected. Lessons learned from this implementation are discussed.

A compact nanopower low output impedance CMOS operational amplifier for wireless intraocular pressure recordings.

PubMed

Dresher, Russell P; Irazoqui, Pedro P

2007-01-01

Wireless sensing has shown potential benefits for the continuous-time measurement of physiological data. One such application is the recording of intraocular pressure (IOP) for patients with glaucoma. Ultra-low-power circuits facilitate the use of inductively-coupled power for implantable wireless systems. Compact circuit size is also desirable for implantable systems. As a first step towards the realization of such circuits, we have designed a compact, ultra-low-power operational amplifier which can be used to record IOP. This paper presents the measured results of a CMOS operational amplifier that can be incorporated with a wireless IOP monitoring system or other low-power application. It has a power consumption of 736 nW, chip area of 0.023 mm2, and output impedance of 69 Omega to drive low-impedance loads.

Topical tissue plasminogen activator appears ineffective for the clearance of intraocular fibrin.

PubMed

Zwaan, J; Latimer, W B

1998-06-01

To determine the efficacy of topical tissue plasminogen activator (tPA) for the resolution of postoperative or inflammatory intraocular fibrinous exudates. Each treatment consisted of drops of 1 mg/ml tPA given 9 times 5 minutes apart. Records were reviewed and the results at 24 and 48 hours were recorded. Sixty-two patients had a total of 94 treatments. Fibrin exudates following intraocular surgery in 34 patients were treated 44 times. In 6 patients there was a positive result. Fibrin associated with intraocular infection was treated in 9 patients. None showed clear improvement. Nineteen patients had a total of 34 treatments for poorly controlled intraocular pressure (IOP) after glaucoma surgery. Five patients showed adequate control of the IOP, 12 did not change, and 2 had a questionable improvement. Eleven patients had adequate IOP control after additional treatment. Seven required suture lysis, 2 ab interno bleb revision, and 2 YAG capsulotomy or iridotomy to reduce the IOP to an acceptable level. Within the limits of this retrospective study and taking into account that fibrin may resolve spontaneously, it appears that topical tPA drops are not effective for the liquefaction of intraocular fibrin after surgery or in association with intraocular inflammation. They did not improve IOP control after glaucoma surgery.

Analysis of the effects of non-supine sleeping positions on the stress, strain, deformation and intraocular pressure of the human eye

NASA Astrophysics Data System (ADS)

Volpe, Peter A.

This thesis presents analytical models, finite element models and experimental data to investigate the response of the human eye to loads that can be experienced when in a non-supine sleeping position. The hypothesis being investigated is that non-supine sleeping positions can lead to stress, strain and deformation of the eye as well as changes in intraocular pressure (IOP) that may exacerbate vision loss in individuals who have glaucoma. To investigate the quasi-static changes in stress and internal pressure, a Fluid-Structure Interaction simulation was performed on an axisymmetrical model of an eye. Common Aerospace Engineering methods for analyzing pressure vessels and hyperelastic structural walls are applied to developing a suitable model. The quasi-static pressure increase was used in an iterative code to analyze changes in IOP over time.

Esterified estrogens combined with methyltestosterone raise intraocular pressure in postmenopausal women.

PubMed

Khurana, Rahul N; LaBree, Laurie D; Scott, Garrett; Smith, Ronald E; Yiu, Samuel C

2006-09-01

To investigate the effect of esterified estrogens combined with methyltestosterone (EECM) (Estratest, Solvay, Pharmaceuticals, Inc, Baudette, Minnesota, USA) on intraocular pressure (IOP) in postmenopausal women. Observational case series. The IOP of 13 consecutive postmenopausal women with dry eye syndrome were recorded before and during EECM therapy (1.25 mg of esterified estrogens and 2.5 mg of methyltestosterone for several months). The mean IOP increased from a baseline of 15.0 mm Hg before treatment to 18.2 mm Hg on EECM therapy (P < .0001) after a median duration of 11.3 months (range, 0.9 to 24 months). The increase in IOP was statistically significant at the 0.05 level of significance within three months and continued over 12 months. Two patients whose pressures increased (>4 mm Hg) returned to baseline levels after EECM was discontinued. Esterified estrogens combined with methyltestosterone produce a clinically significant increase in IOP in postmenopausal women with dry eye syndrome.

Real-time determination of fringe pattern frequencies: An application to pressure measurement

NASA Astrophysics Data System (ADS)

Sciammarella, Cesar A.; Piroozan, Parham

2007-05-01

Retrieving information in real time from fringe patterns is a topic of a great deal of interest in scientific and engineering applications of optical methods. This paper presents a method for fringe frequency determination based on the capability of neural networks to recognize signals that are similar but not identical to signals used to train the neural network. Sampled patterns are generated by calibration and stored in memory. Incoming patterns are analyzed by a back-propagation neural network at the speed of the recording device, a CCD camera. This method of information retrieval is utilized to measure pressures on a boundary layer flow. The sensor combines optics and electronics to analyze dynamic pressure distributions and to feed information to a control system that is capable to preserve the stability of the flow.

Effect of interscalene block on intraocular pressure and ocular perfusion pressure.

PubMed

Basaran, Betul; Yilbas, Aysun Ankay; Gultekin, Zeki

2017-10-23

Interscalene block (ISB) is commonly associated with Horner's syndrome due to spread of local anesthetic to the cervical sympathetic chain. Postganglionic neurons that originate from superior cervical ganglia form the sympathetic innervation of eye. Decrease in sympathetic tone may change intraocular pressure (IOP) and ocular perfusion pressure (OPP). The aim of the study was to investigate whether ISB affects IOP and/or OPP. Thirty patients scheduled for ambulatory shoulder surgery under regional anesthesia with a single-shot ISB (15 mL 0.5% bupivacaine and 15 mL 2% lidocaine) were recruited. The IOP and OPP in both eyes, mean arterial pressure (MAP), heart rate (HR) and end-tidal CO 2 (ETCO 2 ) were measured before ISB and 5, 10, 20, 30 and 60 min after ISB in the beach-chair position. The baseline IOP and OPP were similar in the blocked and unblocked sides (IOP 17.60 ± 1.69 and 17.40 ± 1.96 respectively p = 0.432; OPP 49.80 ± 8.20 and 50 ± 8.07 respectively p = 0.432). The IOP in the blocked side significantly decreased between 10th to 60th min following ISB, compared to the baseline values (p < 0.001). The OPP in the blocked side significantly increased from 10th to 60th min (p < 0.001) whereas, there were no significant changes in IOP and OPP throughout the measurement period in the unblocked side. ISB decreased IOP in the blocked side. ISB could be considered as a safe regional technique of choice in elderly patients at high risk for developing glaucoma.

Survey of ophthalmic anterior segment findings and intraocular pressure in 95 North American box turtles (Terrapene spp.).

PubMed

Espinheira Gomes, Filipe; Brandão, João; Sumner, Julia; Kearney, Michael; Freitas, Inês; Johnson, James; Cutler, Daniel; Nevarez, Javier

2016-03-01

To describe the ophthalmic biomicroscopy findings and intraocular pressures (IOP) in a captive population of box turtles and to determine whether a relationship exists between body morphometrics or health status and IOP. Hundred and three box turtles (69 Gulf coast, 24 three-toed, one ornate, one eastern, and eight unidentified) were triaged into three different color-coded groups: green (healthy), yellow (abnormal physical examination with no need for immediate care), and red (immediate care required). Both eyes were evaluated by rebound tonometry and slit-lamp biomicroscopy. Body weight and morphometric data were recorded. Intraocular pressures measurements were available for 190 eyes, slit-lamp biomicroscopy was available for 170 eyes, and morphometric data were available for 81 turtles. IOP in Gulf coast turtles (138 eyes) was 6.7 ± 1.4 mmHg OU. IOP in three-toed turtles (48 eyes) was 8.3 ± 1.5 mmHg OU, which was significantly higher than in Gulf coast turtles (P < 0.0001). No significant IOP differences were noted between genders in both subspecies (P = 0.768). There was a correlation between IOP and health status in three-toed turtles only. There was a mild negative correlation between morphometrics and IOP in Gulf coast and three-toed turtles. Fifteen of 87 turtles had unilateral corneal or lenticular opacities; 3/87 had bilateral corneal or lenticular disease; and 3/87 had adnexal abnormalities. Different subspecies of box turtles have different normal intraocular pressures as measured by rebound tonometry, which was influenced by the animals' health status in one subspecies. Some morphometric parameters were found to be associated with IOP. Box turtles are often affected with ophthalmic abnormalities of unknown clinical significance. © 2015 American College of Veterinary Ophthalmologists.

A longitudinal study of age-related changes in intraocular pressure: the Kangbuk Samsung Health Study.

PubMed

Zhao, Di; Kim, Myung Hun; Pastor-Barriuso, Roberto; Chang, Yoosoo; Ryu, Seungho; Zhang, Yiyi; Rampal, Sanjay; Shin, Hocheol; Kim, Joon Mo; Friedman, David S; Guallar, Eliseo; Cho, Juhee

2014-09-02

To examine the longitudinal association between age and intraocular pressure (IOP) in a large sample of Korean men and women. We conducted a prospective cohort study of 274,064 young and middle-aged Korean adults with normal fundoscopic findings, following them from January 1, 2002, to February 28, 2010. Health exams were scheduled annually or biennially. At each visit, IOP was measured in both eyes using automated noncontact tonometers. The longitudinal change in IOP with age was evaluated using three-level mixed models for longitudinal paired-eye data, accounting for correlations between paired eyes and repeated measurements over time. In fully adjusted models, the average longitudinal change in IOP per 1-year increase in age was -0.065 mm Hg (95% confidence interval [CI] -0.068 to -0.063), with marked sex differences (P < 0.001). In men, the average annual IOP change was -0.093 mm Hg (95% CI -0.096 to -0.091) throughout follow-up. In women, the average annual IOP change was -0.006 mm Hg (95% CI -0.010 to -0.003), with a relatively flat association in the age range of 30 to 59 years and more marked annual decreases at younger and older ages. Intraocular pressure was inversely associated with age in a large cohort of Korean adults attending health-screening visits. For men, this inverse association was observed throughout the entire age range, while for women it was evident only in younger (<30 years of age) and older (≥60 years of age) women, with no association in women aged 30 to 59. Further research is needed to better understand the underlying mechanisms and to reconsider cutoffs for defining high IOP by age and sex groups in Asian populations. Copyright 2014 The Association for Research in Vision and Ophthalmology, Inc.

A Longitudinal Study of Association between Adiposity Markers and Intraocular Pressure: The Kangbuk Samsung Health Study.

PubMed

Zhao, Di; Kim, Myung Hun; Pastor-Barriuso, Roberto; Chang, Yoosoo; Ryu, Seungho; Zhang, Yiyi; Rampal, Sanjay; Shin, Hocheol; Kim, Joon Mo; Friedman, David S; Guallar, Eliseo; Cho, Juhee

2016-01-01

Intraocular pressure (IOP) reduction or stabilization is the only proven method for glaucoma management. Identifying risk factors for IOP is crucial to understand the pathophysiology of glaucoma. To examine the associations of change in body mass index (BMI), waist circumference, and percent fat mass with change in intraocular pressure (IOP) in a large sample of Korean adults. Cohort study of 274,064 young and middle age Korean adults with normal fundoscopic findings who attended annual or biennial health exams from January 1, 2002 to Feb 28, 2010 (577,981 screening visits). BMI, waist circumference, and percent fat mass. At each visit, IOP was measured in both eyes with automated noncontact tonometers. In multivariable-adjusted models, the average increase in IOP (95% confidence intervals) over time per interquartile increase in BMI (1.26 kg/m2), waist circumference (6.20 cm), and percent fat mass (3.40%) were 0.18 mmHg (0.17 to 0.19), 0.27 mmHg (0.26 to 0.29), and 0.10 mmHg (0.09 to 0.11), respectively (all P < 0.001). The association was stronger in men compared to women (P < 0.001) and it was only slightly attenuated after including diabetes and hypertension as potential mediators in the model. Increases in adiposity were significantly associated with an increase in IOP in a large cohort of Korean adults attending health screening visits, an association that was stronger for central obesity. Further research is needed to understand better the underlying mechanisms of this association, and to establish the role of weight gain in increasing IOP and the risk of glaucoma and its complications.

Design considerations of a real-time clinical confocal microscope

NASA Astrophysics Data System (ADS)

Masters, Barry R.

1991-06-01

A real-time clinical confocal light microscope provides the ophthalmologist with a new tool for the observation of the cornea and the ocular lens. In addition, the ciliary body, the iris, and the sclera can be observed. The real-time light microscopic images have high contrast and resolution. The transverse resolution is about one half micron and the range resolution is one micron. The following observations were made with visible light: corneal epithelial cells, wing cells, basal cells, Bowman's membrane, nerve fibers, basal lamina, fibroblast nuclei, Descemet's membrane, endothelial cells. Observation of the in situ ocular lens showed lens capsule, lens epithelium, lens fibrils, the interior of lens fibrils. The applications of the confocal microscope include: eye banking, laser refractive surgery, observation of wound healing, observation of the iris, the sciera, the ciliary body, the ocular lens, and the intraocular lens. Digital image processing can produce three-dimensional reconstructions of the cornea and the ocular lens.

Experimental observation of intraocular pressure changes during microkeratome suctioning in laser in situ keratomileusis.

PubMed

Bissen-Miyajima, Hiroko; Suzuki, Shintaro; Ohashi, Yoshie; Minami, Keiichiro

2005-03-01

To observe changes in intraocular pressure (IOP), the manner in which the eye is suctioned, and the effect of the number of suction ports. Department of Ophthalmology, Tokyo Dental College, Suidobashi Hospital, Tokyo, Japan. Suction rings with single or dual ports were made of transparent acrylic acid resin to facilitate observation with a digital video camera. The IOP and the duration of the IOP increase (time to reach 90% of the maximum IOP) were measured in 6 porcine eyes with an intra-vein pressure-sensor catheter in the vitreous cavity. The IOP changes were recorded using a personal computer. Suctioning with single- and dual-port suction rings was similar. The IOP increases with single- and dual-port suction rings were similar (99.1 mm Hg +/- 6.1 [SD] and 99.0 +/- 6.5 mm Hg, respectively) (P=.987). The duration of the IOP increase was also similar (4.21 +/- 0.24 seconds and 4.12 +/- 0.33 seconds, respectively) (P=.190). The number of ports did not affect suctioning and changes in IOP. This technique is useful in developing the ideal shape and setting of the suction ring.

Short-Term Intraocular Pressure Rise during Locally Induced Force by Ophthalmologic Surgery Applications.

PubMed

Koelbl, Philipp Simon; Werner, Jens Ulrich; Enders, Christian; Lingenfelder, Christian; Koch, Frank H J; Hessling, Martin

2018-05-31

Surgical or diagnostic procedures are often accompanied by a short-term increase in intraocular pressure (IOP). A short-term increase in IOP can occur during refractive procedures, vitreoretinal surgery, transillumination, photocoagulation, or cryocoagulation. A porcine eye model was chosen (n = 89) to compile comparable study data and to de termine correlations between the force induced and the resulting intraocular pressure while excluding the effect of surgeons. The IOP was measured in the anterior chamber. IOP changes were induced by applying an external force and measured when using a cannula, trocar, and cryocoagulation (n = 32), and correlations between force and resulting IOP were assessed (n = 57). A correlation was noted between the force induced and the IOP increase, which showed a linear dependency. The insertion of a 29-G cannula caused a mean ΔIOP value of 49.1 ± 2.9 mm Hg and an external force of 0.76 N, and that of a 23-G trocar 344.4 ± 5.9 mm Hg and 6.09 N, respectively. The rise in IOP during a simulated cryocoagulation reached values between 57.3 ± 14.8 mm Hg (cryoprobe tip diameter: 0.9 mm) and 130.3 ± 2.9 mm Hg (cryoprobe tip diameter: 7.0 mm). The values of the forces applied can be converted into the resulting IOP based on the specific action. Surgical or diagnostic procedures should, therefore, be evaluated with regard to preexisting pathologies, such as glaucoma. © 2018 S. Karger AG, Basel.

The Effect of Labor on the Intraocular Pressure in Healthy Women.

PubMed

Meshi, Amit; Armarnik, Sharon; Mimouni, Michael; Segev, Fani; Segal, Ori; Kaneti, Hagai; Assia, Ehud I; Geffen, Noa

2017-01-01

To investigate the effect of modern vaginal labor using epidural anesthesia on the intraocular pressure (IOP) and on the mean ocular perfusion pressure (MOPP) in healthy women. In this prospective observational study, eligible candidates were healthy pregnant women for vaginal delivery with epidural anesthesia, with a singleton pregnancy, who were admitted to the delivery room in the first phase of the first stage of labor. Demographic data as well as medical and obstetric history were obtained at baseline, followed by performance of a biomicroscopic examination. IOP, maternal heart rate, systolic blood pressure, and diastolic blood pressure were measured in the first, second and third stages of labor, 24±2 and 48±2 hours postpartum. IOP was not measured during the contraction phase of stage 2. MOPP was expressed as the difference between the arterial blood pressure and the IOP. Measurements were performed throughout the different stages of labor and were compared with baseline values. Thirty healthy white women were enrolled. Four women dropped out due to unexpected cesarean sections. The average age was 31.8±4.7 years. Nineteen participants received oxytocin during delivery. Twenty-three women were placed in a supine position, whereas 3 in a left decubitus position. No statistically significant changes were recorded in IOP (P=0.50) or MOPP (P=0.17) throughout the different stages of vaginal labor in this study. Vaginal delivery under epidural anesthesia is unlikely to cause significant damage to the optic nerve in healthy women.

Evaluation of monkey intraocular pressure by rebound tonometer

PubMed Central

Yu, Wenhan; Cao, Guiqun; Qiu, Jinghua; Ma, Jia; Li, Ni; Yu, Man; Yan, Naihong; Chen, Lei; Pang, Iok-Hou

2009-01-01

Purpose To evaluate the usefulness of the TonoVet™ rebound tonometer in measuring intraocular pressure (IOP) of monkeys. Methods The accuracy of the TonoVet™ rebound tonometer was determined in cannulated eyes of anesthetized rhesus monkeys where IOP was controlled by adjusting the height of a connected perfusate reservoir. To assess the applicability of the equipment through in vivo studies, the diurnal fluctuation of IOP and effects of IOP-lowering compounds were evaluated in monkeys. Results IOP readings generated by the TonoVet™ tonometer correlated very well with the actual pressure in the cannulated monkey eye. The linear correlation had a slope of 0.922±0.014 (mean±SEM, n=4), a y-intercept of 3.04±0.61, and a correlation coefficient of r2=0.97. Using this method, diurnal IOP fluctuation of the rhesus monkey was demonstrated. The tonometer was also able to detect IOP changes induced by pharmacologically active compounds. A single topical ocular instillation (15 μg) of the rho kinase inhibitor, H1152, produced a 5–6 mmHg reduction (p<0.001) in IOP, lasting at least 4 h. In addition, topical administration of Travatan®, a prostaglandin agonist, induced a small transient IOP increase (1.1 mmHg versus vehicle control; p=0.26) at 2 h after treatment followed by a pressure reduction at 23 h (−2.4 mmHg; p<0.05). Multiple daily dosing with the drug produced a persistent IOP-lowering effect. Three consecutive days of Travatan treatment produced ocular hypotension of −2.0 to −2.2 mmHg (p<0.05) the following day. Conclusions The rebound tonometer was easy to use and accurately measured IOP in the rhesus monkey eye. PMID:19898690

The Real-World Effect of Intravitreous Anti-Vascular Endothelial Growth Factor Drugs on Intraocular Pressure: An Analysis Using the IRIS Registry.

PubMed

Atchison, Elizabeth A; Wood, Kevin M; Mattox, Cynthia G; Barry, Catherine N; Lum, Flora; MacCumber, Mathew W

2018-05-01

To identify sustained differences in intraocular pressure (IOP) after intravitreous injections of anti-vascular endothelial growth factor (VEGF) drugs. Database study. Patients seeing an ophthalmic provider who contributes to the database. We identified a total of 23 776 unique patients who received only a single type of anti-VEGF medication (bevacizumab, aflibercept, or ranibizumab) by injection in the right eye in the American Academy of Ophthalmology Intelligent Research in Sight Registry. Subgroups included patients with age-related macular degeneration only and patients who had not received an anti-VEGF injection for at least 1 year before the study. We examined those with at least 12, 18, and 25 injections for each of these 3 medications. For all groups, we used fellow, untreated eyes for comparison. The mean change in IOP from baseline at a minimum of 1 year of follow-up and the proportion of eyes with a clinically significant IOP increase (defined as sustained rise of at least 6 mmHg to an IOP of more than 21 mmHg). All patients in all groups receiving all drugs showed a decrease in IOP from baseline, with a mean of 0.9 mmHg in treated eyes compared with an average decrease of 0.2 mmHg in fellow untreated eyes, a statistically significant difference. A generalized linear model accounting for confounders associated bevacizumab with slightly less lowering of IOP than aflibercept and ranibizumab in most subgroups. A clinically significant IOP increase was seen in 2.6% of eyes receiving injections compared with 1.5% in the associated untreated fellow eyes. Clinically significant IOP increases occurred at a rate of 1.9%, 2.8%, and 2.8% for aflibercept, ranibizumab, and bevacizumab, respectively, which was significantly higher than untreated fellow eyes for bevacizumab and ranibizumab, but not for aflibercept. These analyses from real-world data indicate that anti-VEGF intravitreous injections are associated with a small but statistically significant decrease

Seasonal changes of 24-hour intraocular pressure rhythm in healthy Shanghai population

PubMed Central

Cheng, Jingyi; Xiao, Ming; Xu, Huan; Fang, Shaobin; Chen, Xu; Kong, Xiangmei; Sun, Xinghuai

2016-01-01

Abstract The aim of the present study was to investigate and compare the 24-hour intraocular pressure (IOP) rhythms in winter and summer in the healthy population of Shanghai, China. This is a cross-sectional study in which 24-hour IOP measurements were taken for all eligible healthy volunteers in winter and summer, respectively, and the temperature, hours of sunlight (sunlight time), and circulatory parameters, including heart rate, systolic blood pressure, and diastolic blood pressure, were also recorded. The 24-hour IOP curves and IOP parameters (mean, peak, trough, and fluctuation of IOP together with the diurnal-to-nocturnal IOP change) in winter and summer were obtained and compared. The magnitude of IOP changes from summer to winter was also calculated. A total of 29 participants (58 eyes), 14 (48.28%) male and 15 (51.72%) female, aged 43.66 ± 12.20 (19–61) years, were considered eligible for this study. Generally, IOP decreased progressively before noon, increased notably in the nocturnal period, and peaked at 12:00 am in winter and at 2:00 am in summer. The pattern of 24-hour IOP in winter and summer was significantly different (P = 0.002). The average IOPs from 4:00 pm to 8:00 am, except for 6:00 am, were significantly higher in winter (P < 0.05). However, no significant differences were shown after adjusting for temperature and/or sunlight time. From summer to winter, the extent of IOP increase was mostly around 0 to 3 mm Hg, and the IOPs increased more significantly in the nocturnal period than in the diurnal period (P = 0.05). The 24-hour IOP rhythms were different in winter and summer, with higher IOP level in winter. Temperature and sunlight time, which are independent of heart rate and blood pressure, affected the 24-hour IOP rhythms in healthy people in Shanghai, China. Further investigations are expected for the rhythm of some endogenous substance secretion and the inner mechanism of regulation of IOP. PMID:27495076

Intraocular pressure control of a novel glaucoma drainage device - in vitro and in vivo studies

PubMed Central

Cui, Li-Jun; Li, Di-Chen; Liu, Jian; Zhang, Lei; Xing, Yao

2017-01-01

AIM To evaluate the intraocular pressure (IOP) control of an artificial trabeculum drainage system (ATDS), a newly designed glaucoma drainage device, and postoperative complications in normal rabbit eyes. METHODS Pressure drops in air and fluid of 30 ATDS were measured after being connected to a closed manometric system. Twenty of them were then chosen and implanted randomly into the eyes of 20 rabbits. Postoperative slit-lamp, gonioscopic examination and IOP measurements were recorded periodically. Ultrasound biomicroscopy and B-scan ultrasonography were also used to observe the complications. Eyes were enucleated on day 60. RESULTS Pressure drops of 4.6-9.4 mm Hg were obtained at physiological aqueous flow rates in the tests in vitro. The average postoperative IOP of the experimental eyes (11.6-12.8 mm Hg) was lower than the controls significantly (P<0.05) at each time point. Complications of hemorrhage (n=1), cellulosic exudation (two cases) and local iris congestion (two cases) were observed. The lumina of the devices were devoid of obstructions in all specimens examined and a thin fibrous capsule was found around the endplate. CONCLUSION ATDS reduce IOP effectively. However, further studies on the structure are needed to reduce complications. PMID:28944192

The Impact of Adherence and Instillation Proficiency of Topical Glaucoma Medications on Intraocular Pressure

PubMed Central

Shibeshi, Workineh; T. Giorgis, Abeba; Asgedom, Solomon Weldegebreal

2017-01-01

Background The possible sequel of poorly controlled intraocular pressure (IOP) includes treatment failure, unnecessary medication use, and economic burden on patients with glaucoma. Objective To assess the impact of adherence and instillation technique on IOP control. Methods A cross-sectional study was conducted on 359 glaucoma patients in Menelik II Hospital from June 1 to July 31, 2015. After conducting a Q-Q analysis, multiple binary logistic analyses, linear regression analyses, and two-tailed paired t-test were conducted to compare IOP in the baseline versus current measurements. Results Intraocular pressure was controlled in 59.6% of the patients and was relatively well controlled during the study period (mean (M) = 17.911 mmHg, standard deviation (S) = 0.323) compared to the baseline (M = 20.866 mmHg, S = 0.383, t (358) = −6.70, p < 0.0001). A unit increase in the administration technique score resulted in a 0.272 mmHg decrease in IOP (p = 0.03). Moreover, primary angle-closure glaucoma (adjusted odds ratio (AOR) = 0.347, 95% confidence interval (CI): 0.144–0.836) and two medications (AOR = 1.869, 95% CI: 1.259–9.379) were factors affecting IOP. Conclusion Good instillation technique of the medications was correlated with a reduction in IOP. Consequently, regular assessment of the instillation technique and IOP should be done for better management of the disease. PMID:29104803

The Impact of Adherence and Instillation Proficiency of Topical Glaucoma Medications on Intraocular Pressure.

PubMed

Atey, Tesfay Mehari; Shibeshi, Workineh; T Giorgis, Abeba; Asgedom, Solomon Weldegebreal

2017-01-01

The possible sequel of poorly controlled intraocular pressure (IOP) includes treatment failure, unnecessary medication use, and economic burden on patients with glaucoma. To assess the impact of adherence and instillation technique on IOP control. A cross-sectional study was conducted on 359 glaucoma patients in Menelik II Hospital from June 1 to July 31, 2015. After conducting a Q-Q analysis, multiple binary logistic analyses, linear regression analyses, and two-tailed paired t-test were conducted to compare IOP in the baseline versus current measurements. Intraocular pressure was controlled in 59.6% of the patients and was relatively well controlled during the study period (mean ( M ) = 17.911 mmHg, standard deviation ( S ) = 0.323) compared to the baseline ( M = 20.866 mmHg, S = 0.383, t (358) = -6.70, p < 0.0001). A unit increase in the administration technique score resulted in a 0.272 mmHg decrease in IOP ( p = 0.03). Moreover, primary angle-closure glaucoma (adjusted odds ratio (AOR) = 0.347, 95% confidence interval (CI): 0.144-0.836) and two medications (AOR = 1.869, 95% CI: 1.259-9.379) were factors affecting IOP. Good instillation technique of the medications was correlated with a reduction in IOP. Consequently, regular assessment of the instillation technique and IOP should be done for better management of the disease.

Quantitative assessment of corneal vibrations during intraocular pressure measurement with the air-puff method in patients with keratoconus.

PubMed

Koprowski, Robert; Ambrósio, Renato

2015-11-01

One of the current methods for measuring intraocular pressure is the air-puff method. A tonometer which uses this method is the Corvis device. With the ultra-high-speed (UHS) Scheimpflug camera, it is also possible to observe corneal deformation during measurement. The use of modern image analysis and processing methods allows for analysis of higher harmonics of corneal deflection above 100 Hz. 493 eyes of healthy subjects and 279 eyes of patients with keratoconus were used in the measurements. For each eye, 140 corneal deformation images were recorded during intraocular pressure measurement. Each image was recorded every 230 µs and had a resolution of 200 × 576 pixels. A new, original algorithm for image analysis and processing has been proposed. It enables to separate the eyeball reaction as well as low-frequency and high-frequency corneal deformations from the eye response to an air puff. Furthermore, a method for classification of healthy subjects and patients with keratoconus based on decision trees has been proposed. The obtained results confirm the possibility to distinguish between patients with keratoconus and healthy subjects. The features used in this classification are directly related to corneal vibrations. They are only available in the proposed software and provide specificity of 98%, sensitivity-85%, and accuracy-92%. This confirms the usefulness of the proposed method in this type of classification that uses corneal vibrations during intraocular pressure measurement with the Corvis tonometer. With the new proposed algorithm for image analysis and processing allowing for the separation of individual features from a corneal deformation image, it is possible to: automatically measure corneal vibrations in a few characteristic points of the cornea, obtain fully repeatable measurement of vibrations for the same registered sequence of images and measure vibration parameters for large inter-individual variability in patients. Copyright © 2015 Elsevier

Central Corneal Thickness and its Relationship to Intra-Ocular and Epidmiological Determinants.

PubMed

Tayyab, Ali; Masrur, Amena; Afzal, Farooq; Iqbal, Fyza; Naseem, Kamran

2016-06-01

To measure central corneal thickness in Pakistani population and determine its relationship to intra-ocular pressure, age, gender and ethnicity. Cross-sectional observation study. Pakistan Institute of Medical Sciences, Islamabad, Pakistan, between December 2013 and February 2015. The right eyes of 1000 cases (496 males and 504 females) were recruited for this study. Inclusion criteria were Pashtun or Punjabi ethnicity, intra-ocular pressure < 22 mmHg, gonioscopically open angles, cup-disk-ratio < 0.5, and age matched normal visual fields. Cases with prior ocular surgery, contact lens use, corneal pathologies, myopia or hypermetropia > ±3.0 diopters, astigmatism of > ±1.0 diopters were excluded. Central corneal thickness was measured using a TopCon non-contact specular microscope. Intra-ocular pressure was measured using Goldmann applanation tonometer. Frequency distribution, test of significance, and regression analysis was carried out using Statistical Package for Social Sciences version 20.0. Mean age was 47.31 ±11.78 years. Ethnic composition was 51.6% (n=516) Pashtun and 48.4% (n=484) Punjabi. The mean central corneal thickness was 503.96 (±12.47) µm, while the mean intra-ocular pressure was 15.61 (±2.68) mmHg. Regression analysis showed a significant association between central corneal thickness and intra-ocular pressure (p=0.00) and age (p=0.00). A±100 µchange in central corneal thickness was associated with change in IOPof ±3.30 mmHg, whereas central corneal thickness decreased by 0.12 µm per year. No significant association could be established between central corneal thickness and ethnicity (p=0.19). Central corneal thickness of the studied races was comparable to non-Caucasians which affects intra-ocular pressure measurements, and decreases with increasing age. No relationship was observed between central corneal thickness and ethnicity or gender.

Effect of Sildenafil Citrate on Intraocular Pressure and Blood Pressure in Human Volunteers

PubMed Central

Gerometta, Rosana; Alvarez, Lawrence J.; Candia, Oscar A.

2011-01-01

Anecdotal reports have suggested that the vasodilator, sildenafil citrate, which evokes its effect via a select inhibition of PDE5, has the potential to increase intraocular pressure (IOP) in some individuals. An ocular hypertensive effect by sildenafil was also recently described in a sheep animal model. In contrast, clinical studies have not found a direct association between sildenafil ingestion (commonly consumed as Viagra) and changes in IOP. However, some such studies also reported no effects of sildenafil on systemic blood pressure (BP) at the time of the IOP determination. Given this surprising result, our purpose was to repeat a study in human volunteers in the city of Corrientes, Argentina to corroborate the effects of sildenafil on human IOP and systemic BP. For the present study, 9 healthy volunteers (male and female, 18 to 74 years old) were selected as subjects after ophthalmic and cardiovascular evaluation indicated that they exhibited normal parameters for their age. In a masked, placebo-controlled study, the subjects ingested 100 mg sildenafil citrate (provided as Vorst from Laboratorios Bernabo, Argentina) in one session, and a placebo on a second separate occasion. IOP was measured with a Goldman applanation tonometer by an ophthalmologist, and BP by a second physician, neither of whom witnessed the tablet ingestion by the volunteers, nor provided with information on the nature of the test compounds. A third individual administered the tablets. The average baseline IOP of this group of 9 was 13.1 ± 0.6 mm Hg. Subsequent to sildenafil ingestion, IOP increased by 26% to 16.5 ± 0.8 mm Hg 60 min later (p< 0.005, as paired data), and returned to control values within 2 hrs. Both systolic and diastolic BP were significantly reduced by sildenafil ingestion. At the point of maximal systemic hypotension (90 min), the systolic and diastolic pressures declined by 15% and 13%, respectively. No significant changes in IOP or BP were recorded after ingestion

The effects of Helicobacter pylori infection on intraocular pressure in anterior uveitis

PubMed Central

Kim, J M; Park, K H; Choi, M J; Ha, M M; Sohn, Y H; Kim, H K; Caprioli, J

2012-01-01

Purpose We investigated the influence of H. pylori infection on intraocular pressure (IOP) in anterior uveitis patients to clarify whether H. pylori infection is related to high IOP in anterior uveitis. Methods In this prospective study, 165 Korean anterior uveitis patients were examined. All patients underwent serological analysis to identify the cause of uveitis, including the presence of H. pylori infection by enzyme-linked immunosorbent assay. Serological values were compared between patients with and without high IOP. Results Seropositivity for H. pylori was 69.70% of patients with high IOP and 38.38% of patients with normal IOP (P<0.01). Conclusion This study suggests that H. pylori infection is associated with high IOP in anterior uveitis. PMID:23154495

Development of a real-time monitoring system for intra-fractional motion in intracranial treatment using pressure sensors.

PubMed

Inata, Hiroki; Araki, Fujio; Kuribayashi, Yuta; Hamamoto, Yasushi; Nakayama, Shigeki; Sodeoka, Noritaka; Kiriyama, Tetsukazu; Nishizaki, Osamu

2015-09-21

This study developed a dedicated real-time monitoring system to detect intra-fractional head motion in intracranial radiotherapy using pressure sensors. The dedicated real-time monitoring system consists of pressure sensors with a thickness of 0.6 mm and a radius of 9.1 mm, a thermoplastic mask, a vacuum pillow, and a baseplate. The four sensors were positioned at superior-inferior and right-left sides under the occipital area. The sampling rate of pressure sensors was set to 5 Hz. First, we confirmed that the relationship between the force and the displacement of the vacuum pillow follows Hook's law. Next, the spring constant for the vacuum pillow was determined from the relationship between the force given to the vacuum pillow and the displacement of the head, detected by Cyberknife target locating system (TLS) acquisitions in clinical application. Finally, the accuracy of our system was evaluated by using the 2  ×  2 confusion matrix. The regression lines between the force, y, and the displacement, x, of the vacuum pillow were given by y = 3.8x, y = 4.4x, and y = 5.0x when the degree of inner pressure was  -12 kPa,-20 kPa, and  -27 kPa, respectively. The spring constant of the vacuum pillow was 1.6 N mm(-1) from the 6D positioning data of a total of 2999 TLS acquisitions in 19 patients. Head motions of 1 mm, 1.5 mm, and 2 mm were detected in real-time with the accuracies of 67%, 84%, and 89%, respectively. Our system can detect displacement of the head continuously during every interval of TLS with a resolution of 1-2 mm without any radiation exposure.

High intraocular pressure produces learning and memory impairments in rats.

PubMed

Yuan, Yuxiang; Chen, Zhiqi; Li, Lu; Li, Xing; Xia, Qian; Zhang, Hong; Duan, Qiming; Zhao, Yin

2017-11-15

Primary open angle glaucoma (POAG) is a leading cause of irreversible blindness worldwide. Previous MRI studies have revealed that POAG can be associated with alterations in hippocampal function. Thus, the aim of this study was to investigate a relationship between chronic high intraocular pressure (IOP) and hippocampal changes in a rat model. We used behavioural tests to assess learning and memory ability, and additionally investigated the hippocampal expression of pathological amyloid beta (Aβ), phospho-tau, and related pathway proteins. Chronic high IOP impaired learning and memory in rats and concurrently increased Aβ and phospho-tau expression in the hippocampus by altering the activation of different kinase (GSK-3β, BACE1) and phosphatase (PP2A) proteins in the hippocampus. This study provides novel evidence for the relationship between high IOP and hippocampal alterations, especially in the context of learning and memory. Copyright © 2017 Elsevier B.V. All rights reserved.

A Longitudinal Study of Association between Adiposity Markers and Intraocular Pressure: The Kangbuk Samsung Health Study

PubMed Central

Zhao, Di; Kim, Myung Hun; Pastor-Barriuso, Roberto; Chang, Yoosoo; Ryu, Seungho; Zhang, Yiyi; Rampal, Sanjay; Shin, Hocheol; Kim, Joon Mo; Friedman, David S.; Guallar, Eliseo; Cho, Juhee

2016-01-01

Importance Intraocular pressure (IOP) reduction or stabilization is the only proven method for glaucoma management. Identifying risk factors for IOP is crucial to understand the pathophysiology of glaucoma. Objective To examine the associations of change in body mass index (BMI), waist circumference, and percent fat mass with change in intraocular pressure (IOP) in a large sample of Korean adults. Design, setting and participants Cohort study of 274,064 young and middle age Korean adults with normal fundoscopic findings who attended annual or biennial health exams from January 1, 2002 to Feb 28, 2010 (577,981 screening visits). Exposures BMI, waist circumference, and percent fat mass. Main Outcome Measure(s) At each visit, IOP was measured in both eyes with automated noncontact tonometers. Results In multivariable-adjusted models, the average increase in IOP (95% confidence intervals) over time per interquartile increase in BMI (1.26 kg/m2), waist circumference (6.20 cm), and percent fat mass (3.40%) were 0.18 mmHg (0.17 to 0.19), 0.27 mmHg (0.26 to 0.29), and 0.10 mmHg (0.09 to 0.11), respectively (all P < 0.001). The association was stronger in men compared to women (P < 0.001) and it was only slightly attenuated after including diabetes and hypertension as potential mediators in the model. Conclusions and Relevance Increases in adiposity were significantly associated with an increase in IOP in a large cohort of Korean adults attending health screening visits, an association that was stronger for central obesity. Further research is needed to understand better the underlying mechanisms of this association, and to establish the role of weight gain in increasing IOP and the risk of glaucoma and its complications. PMID:26731527

Intraoperative assessment of intraocular pressure in vitrectomized air-filled and fluid-filled eyes.

PubMed

Moon, Chan Hee; Choi, Kyung Seek; Rhee, Mi Ri; Lee, Sung Jin

2013-11-01

To ascertain the difference of intraocular pressure (IOP) measurement between vitrectomized air-filled and fluid-filled eyes. Thirty-one eyes of 31 consecutive patients who underwent conventional vitrectomy and intraocular gas tamponade were assessed. After vitrectomy, IOP of the fluid-filled eyes was measured by Tono-Pen. Thereafter, fluid-air exchange was performed, and IOP of the air-filled eyes was measured again. The IOP within each fluid- and air-filled eye was varied by selecting settings on the vitrectomy system, from 10 to 50 mmHg with 5-mmHg increments. Postoperatively, IOP was assessed by both Tono-Pen and Goldmann applanation tonometry (GAT). Linear and nonlinear regression analyses were conducted between intraoperatively measured Tono-Pen readings and actual IOPs. Bland-Altman plot was used to assess the agreements between postoperatively measured Tono-Pen readings and GAT readings. The discrepancy between Tono-Pen readings and actual IOP in fluid-filled eyes was not significant, except for the profound high pressures over 45 mmHg. However, Tono-Pen readings in air-filled eyes were significantly lower than actual IOPs in all ranges, and Tono-Pen increasingly underestimates IOP at higher levels. Intraoperative Tono-Pen readings were correlated significantly with actual IOP and a quadratic equation evidenced the best fit (R(2) = 0.996). Postoperatively, difference of the measurements between Tono-Pen and GAT was not significant. Tono-Pen and GAT significantly underestimate actual IOP in air-filled eyes. It should be considered that actual IOP would be greater than the measured IOP in gas-filled eyes, even though the IOP is measured as normal. © 2013 Acta Ophthalmologica Scandinavica Foundation. Published by John Wiley & Sons Ltd.

Correlation Between Corneal Button Size and Intraocular Pressure During Femtosecond Laser-Assisted Keratoplasty.

PubMed

Choi, Mihyun; Lee, Yong Eun; Whang, Woong-Joo; Yoo, Young-Sik; Na, Kyung-Sun; Joo, Choun-Ki

2016-03-01

To evaluate changes in intraocular pressure (IOP) in recipient and donor eyes during femtosecond laser-assisted keratoplasty (FLAK) and to assess for differences in the diameter of trephinated corneal buttons according to changes in pressure. Twenty porcine whole eyes (recipient model) and 20 porcine-corneoscleral rims (donor model) were prepared, and anterior chamber pressures were measured using a fiberoptic sensing device (Opsens, Quebec, Canada) during the femtosecond laser corneal cutting process. To determine the diameter of corneal buttons, 10 porcine whole eyes (recipient model) and 12 corneoscleral rims (donor model) of each baseline IOP were cut with the femtosecond laser programmed to the following pattern: "vertical side cut"; 1200 μm (depth), 8 mm (diameter). Digital photographs were obtained using microscopy and subsequently analyzed. The IOP (mean ± SD) for the recipient model was 10.2 (±0.9) mm Hg at baseline and ranged from 96.6 (±4.5) to ∼138.4 (±3.8) mm Hg during the corneal cutting process. This shows that the maximum IOP during FLAK increased 13.5 times compared with baseline. In the donor model, the mean pressure elevation from baseline artificial anterior chamber (AAC) pressure to corneal cutting was 15.8 (±5.4) mm Hg. This showed a positive correlation with baseline IOP [correlation coefficient (CC) = 0.827, P = 0.006]. As the baseline IOP in the recipient eye increased, trephinated corneal button size was reduced by up to 3.9% in diameter (CC = -0.945, P = 0.015). In addition, in donor eyes, the diameter was decreased by up to 11.7% as the baseline AAC pressure increased (CC = -0.934, P = 0.006). During the FLAK procedure, the IOP increases in both recipient and donor eyes. The diameter of the trephinated donor and recipient corneal buttons was decreased as the initial baseline IOP increased. Ophthalmic surgeons can determine the AAC pressure based on the baseline IOP in the recipient patient.

Assessing the True Intraocular Pressure in the Non-human Primate.

PubMed

McAllister, Faith; Harwerth, Ronald; Patel, Nimesh

2018-02-01

For glaucoma patients, high intraocular pressure (IOP) is a risk factor for progressive neuropathy. Similarly, animal models used to study the disease are based on an experimental elevation of IOP. Thus, accurate IOP measurements are important in characterizing experimental models and resulting effects. The purpose of the present study was to investigate IOP measurements in a non-human primate model of experimental glaucoma by comparing clinical tonometry (Tono-Pen and TonoVet) to the true IOP from intracameral manometry. A total of 17 rhesus macaque eyes from 12 animals were used for this study. Eleven eyes had no previous experimental intervention, whereas six eyes were at varying stages of laser-induced experimental glaucoma. IOPs were adjusted by inserting a needle in the anterior chamber that was attached to a pressure transducer and syringe pump system. The anterior chamber IOP was adjusted to values between 10 and 50 mmHg and corresponding measures with Tono-Pen and TonoVet were taken. The IOPs by TonoVet and Tono-Pen were linearly related over the range of pressures tested (slope = 0.68 normal/healthy and 0.72 experimental glaucoma). For the most, TonoVet measures overestimated IOP at all anterior chamber pressure settings (mean difference of 3.17 mmHg, 95% CI 12.53 to -4.74 normal and 3.90 mmHg, 95% CI 12.90 to -6.53 experimental glaucoma). In contrast, Tono-Pen measures overestimated IOP at lower IOPs and underestimated at higher IOP (slope = -0.26 normal and -0.21 experimental glaucoma). The TonoVet and Tono-Pen tonometers that are often used to assess IOP in both clinical and experimental settings generally reflect the status of IOP, but the results from this study suggest that the instruments need calibration with true anterior chamber pressure for accurate measures in experimental models of glaucoma.

Pigment dispersion syndrome associated with intraocular lens implantation: a new surgical technique.

PubMed

Canut Jordana, M Isabel; Pérez Formigó, Daniel; Abreu González, Rodrigo; Nadal Reus, Jeroni

2010-11-11

We report the case of a myopic patient who, after intraocular lens transplant in the posterior chamber, suffered elevated intraocular pressure due to pigment dispersion, with recurrent episodes of blurred vision. The patient was treated with a new surgical technique that can avoid potential iridolenticular contact. Complete ophthalmologic examination and optical coherence tomography (OCT) of the anterior segment were performed. Contact between the pigmentary epithelium and the iris with an intraocular lens was revealed by utrasound biomicroscopy and OCT. In this case, Nd:YAG laser iridotomy and laser iridoplasty were not effective for iridolenticular separation and control of the pigment dispersion. We propose a new technique: stitches on the surface of the iris to obtain good iridolenticular separation and good intraocular pressure control. Stitches on the iris surface should be considered as optional therapy in pigmentary glaucoma secondary to intraocular lens implantation. This surgical technique can avoid potential iridolenticular contacts more definitively.

Arterial and intraocular pressure changes after a single-session hot-water immersion.

PubMed

Findikoglu, Gulin; Cetin, Ebru Nevin; Sarsan, Ayse; Senol, Hande; Yildirim, Cem; Ardic, Fusun

2015-01-01

The aim of this study is to investigate the effect of head-out hot-water immersion on the intraocular pressure (IOP) of healthy subjects and investigate whether this intervention alters cardiovascular and microcirculatory responses. METHODs: 16 male and 18 female healthy young adults were immersed in 39 degrees C water up to shoulder level for 20 minutes. Blood pressure (BP), heart rate (HR) and IOP were measured pre-immersion, post-immersion and five minutes after immersion on the same day. Tono-Pen was used to measure IOP. Mean arterial blood pressure (MAP), systolic pressure rate product (S-PRP), diastolic pressure rate product (D-PRP), pulse pressure (PP), mean ocular perfusion pressure (mean-OPP), systolic ocular perfusion pressure (S-OPP) and diastolic ocular perfusion pressure (D-OPP) were calculated. Systolic BP (SBP), diastolic BP (DBP), MAP, IOP, S-OPP, D-OPP and mean-OPP decreased; HR increased five minutes after immersion in the pool and post-immersion out of the pool significantly, compared to pre-immersion data (p < 0.05). HR, S-PRP and D-PRP measured five minutes after immersion were significantly higher from post-immersion (p < 0.05). PP and S-OPP were significantly different five minutes after immersion compared to pre-immersion. There was no statistically significant correlation between IOP and SBP, DBP, MAP, S-PRP, D-PRP, PP, S-OPP, D-OPP, or mean-OPP (p > 0.05). Physiological hemodynamic response to single head-out hot-water immersion caused a statistically significant decrease in IOP. Preliminary results could help to clarify vascular reactions and IOP changes during hot-water immersion that might be potentially therapeutic in glaucoma patients.

Study of the effect of distance and misalignment between magnetically coupled coils for wireless power transfer in intraocular pressure measurement.

PubMed

Rendon-Nava, Adrian E; Díaz-Méndez, J Alejandro; Nino-de-Rivera, Luis; Calleja-Arriaga, Wilfrido; Gil-Carrasco, Felix; Díaz-Alonso, Daniela

2014-01-01

An analysis of the effect of distance and alignment between two magnetically coupled coils for wireless power transfer in intraocular pressure measurement is presented. For measurement purposes, a system was fabricated consisting of an external device, which is a Maxwell-Wien bridge circuit variation, in charge of transferring energy to a biomedical implant and reading data from it. The biomedical implant is an RLC tank circuit, encapsulated by a polyimide coating. Power transfer was done by magnetic induction coupling method, by placing one of the inductors of the Maxwell-Wien bridge circuit and the inductor of the implant in close proximity. The Maxwell-Wien bridge circuit was biased with a 10 MHz sinusoidal signal. The analysis presented in this paper proves that wireless transmission of power for intraocular pressure measurement is feasible with the measurement system proposed. In order to have a proper inductive coupling link, special care must be taken when placing the two coils in proximity to avoid misalignment between them.

Effect of Intravenous Mannitol on Intraocular Pressure in Vitrectomized Silicone-Oil-Filled Eyes.

PubMed

Takkar, Brijesh; Chandra, Parijat; Shah, Ritu; Bhatia, Indrish; Roy, Sangeeta; Sihota, Ramanjit

2017-01-01

To evaluate the effect of intravenous mannitol (IVM) on intraocular pressure (IOP) in vitrectomized eyes. Thirty-one patients with raised IOP after retinal surgery with silicone oil injection were included. Patients were administered IVM (20% solution, 1g/Kg, over 30 minutes) and IOP was noted at regular intervals. IOP reduction in vitrectomized eyes (Group 1) was compared with the normal eyes (Group 2). Percentage IOP reduction was higher in Group 1 than in Group 2 at all time intervals, 24.5% vs. 19.2% at 15 minutes (p=0.34), 22.6% vs. 9.8% at 45 minutes (p=0.003), 19.1% vs. 9.9% at two hours (p=0.023), and 16.1% vs. 7.8% at four hours (p=0.04), respectively. In Group 1, 40% eyes had an IOP reduction of 2-6 mmHg while 30% eyes had IOP reduction >6 mmHg at four hours post-IVM. IVM is useful for short-term IOP reduction in vitrectomized eyes. IOP reduction is independent of baseline IOP, and sustained and higher as compared to normal eyes.

Biomechanical properties of crystalline lens as a function of intraocular pressure assessed noninvasively by optical coherence elastography

NASA Astrophysics Data System (ADS)

Wu, Chen; Aglyamov, Salavat R.; Liu, Chih-Hao; Han, Zhaolong; Singh, Manmohan; Larin, Kirill V.

2017-02-01

Many ocular diseases such as glaucoma and uveitis can lead to the elevation of intraocular pressure (IOP). Previous research implies a link between elevated IOP and lens disease. However, the relationship between IOP elevation and biomechanical properties of the crystalline lens has not been directly studied yet. In this work, we investigated the biomechanical properties of porcine lens as a function of IOP by acoustic radiation force optical coherence elastography.

Laser-assisted formation of micropores and nanobubbles in sclera promote stable normalization of intraocular pressure

NASA Astrophysics Data System (ADS)

Baum, Olga; Wachsmann-Hogiu, Sebastian; Milner, Thomas; Sobol, Emil

2017-06-01

Pores in sclera enhance uveoscleral water outflow and can normalize intraocular pressure in glaucomatous eyes. The aims of this study are to demonstrate laser-induced formation of pores with a dendritic structure and to answer the questions: How is a pore system stable and can laser treatment provide a long-lasting pressure stabilization effect? Effect of 1.56 µm laser radiation on porcine eye sclera was studied using atomic force microscopy and super resolution structured irradiation microscopy with fluorescent markers. Results suggest that the pores with a complex spatial configuration can arise as a result of laser irradiation and that laser-generated stable gas nanobubbles coated with calcium ions allow pore stabilization in the sclera. Our results support a laser based approach for treatment of glaucoma.

New method for remote and repeatable monitoring of intraocular pressure variations.

PubMed

Margalit, Israel; Beiderman, Yevgeny; Skaat, Alon; Rosenfeld, Elkanah; Belkin, Michael; Tornow, Ralf-Peter; Mico, Vicente; Garcia, Javier; Zalevsky, Zeev

2014-02-01

We present initial steps toward a new measurement device enabling high-precision, noncontact remote and repeatable monitoring of intraocular pressure (IOP)-based on an innovative measurement principle. Using only a camera and a laser source, the device measures IOP by tracking the secondary speckle pattern trajectories produced by the reflection of an illuminating laser beam from the iris or the sclera. The device was tested on rabbit eyes using two different methods to modify IOP: via an infusion bag and via mechanical pressure. In both cases, the eyes were stimulated with increasing and decreasing ramps of the IOP. As IOP variations changed the speckle distributions reflected back from the eye, data were recorded under various optical configurations to define and optimize the best experimental configuration for the IOP extraction. The association between the data provided by our proposed device and that resulting from controlled modification of the IOP was assessed, revealing high correlation (R2=0.98) and sensitivity and providing a high-precision measurement (5% estimated error) for the best experimental configuration. Future steps will be directed toward applying the proposed measurement principle in clinical trials for monitoring IOP with human subjects.

Effect of Hemifacial Spasm on Intraocular Pressure Measurement.

PubMed

Cicik, Erdogan; Yildirim, Rengin; Arici, Ceyhun; Dikkaya, Funda; Arslan, Osman Sevki

2018-01-01

To evaluate the effect of hemifacial spasm (HFS) on intraocular pressure (IOP) measurement. Twenty-four consecutive patients with HFS and 25 age- and gender-matched randomly selected eyes of healthy volunteers underwent corneal pachymetry and IOP measurements using Goldmann applanation tonometer (GAT) and noncontact tonometer (NCT). IOP measurements were performed before (during HFS) and 2 weeks after Botox injections in HFS patients and in healthy volunteers without Botox injections. There was no statistical difference between involved eye side and uninvolved eye side of HFS patients in measured central corneal thickness. Similarly, no difference was found between involved eye side of HFS patients and controls. There were no statistically significant differences comparing IOP values before treatment and levels measured at 2 weeks of Botox injections, either with GAT ( p = 0.33, 0.11) or NCT ( p = 0.80, 0.43) devices in the involved eyes and uninvolved eyes of patients with HFS, respectively. There were also no significant differences in these parameters (GAT ( p = 0.63) and NCT ( p = 0.54)) in controls. Contractions in facial muscles may not lead to significant increase in IOP in HFS patients. This result may help clinical decision making in the treatment of glaucoma patients with HFS. This trial is registered with NCT03390803.

A real time study of the human equilibrium using an instrumented insole with 3 pressure sensors.

PubMed

Abou Ghaida, Hussein; Mottet, Serge; Goujon, Jean-Marc

2014-01-01

The present work deals with the study of the human equilibrium using an ambulatory e-health system. One of the point on which we focus is the fall risk, when losing equilibrium control. A specific postural learning model is presented, and an ambulatory instrumented insole is developed using 3 pressures sensors per foot, in order to determine the real-time displacement and the velocity of the centre of pressure (CoP). The increase of these parameters signals a loss of physiological sensation, usually of vision or of the inner ear. The results are compared to those obtained from classical more complex systems.

A new real-time tsunami detection algorithm

NASA Astrophysics Data System (ADS)

Chierici, F.; Embriaco, D.; Pignagnoli, L.

2016-12-01

Real-time tsunami detection algorithms play a key role in any Tsunami Early Warning System. We have developed a new algorithm for tsunami detection based on the real-time tide removal and real-time band-pass filtering of sea-bed pressure recordings. The algorithm greatly increases the tsunami detection probability, shortens the detection delay and enhances detection reliability, at low computational cost. The algorithm is designed to be used also in autonomous early warning systems with a set of input parameters and procedures which can be reconfigured in real time. We have also developed a methodology based on Monte Carlo simulations to test the tsunami detection algorithms. The algorithm performance is estimated by defining and evaluating statistical parameters, namely the detection probability, the detection delay, which are functions of the tsunami amplitude and wavelength, and the occurring rate of false alarms. Pressure data sets acquired by Bottom Pressure Recorders in different locations and environmental conditions have been used in order to consider real working scenarios in the test. We also present an application of the algorithm to the tsunami event which occurred at Haida Gwaii on October 28th, 2012 using data recorded by the Bullseye underwater node of Ocean Networks Canada. The algorithm successfully ran for test purpose in year-long missions onboard the GEOSTAR stand-alone multidisciplinary abyssal observatory, deployed in the Gulf of Cadiz during the EC project NEAREST and on NEMO-SN1 cabled observatory deployed in the Western Ionian Sea, operational node of the European research infrastructure EMSO.

Effect of sildenafil citrate on intraocular pressure and blood pressure in human volunteers.

PubMed

Gerometta, Rosana; Alvarez, Lawrence J; Candia, Oscar A

2011-07-01

Anecdotal reports have suggested that the vasodilator, sildenafil citrate, which evokes its effect via a select inhibition of PDE5, has the potential to increase intraocular pressure (IOP) in some individuals. An ocular hypertensive effect by sildenafil was also recently described in a sheep animal model. In contrast, clinical studies have not found a direct association between sildenafil ingestion (commonly consumed as Viagra) and changes in IOP. However, some such studies also reported no effects of sildenafil on systemic blood pressure (BP) at the time of the IOP determination. Given this surprising result, our purpose was to repeat a study in human volunteers in the city of Corrientes, Argentina to corroborate the effects of sildenafil on human IOP and systemic BP. For the present study, 9 healthy volunteers (male and female, 18-74 years old) were selected as subjects after ophthalmic and cardiovascular evaluation indicated that they exhibited normal parameters for their age. In a masked, placebo-controlled study, the subjects ingested 100 mg sildenafil citrate (provided as Vorst from Laboratorios Bernabo, Argentina) in one session, and a placebo on a second separate occasion. IOP was measured with a Goldman applanation tonometer by an ophthalmologist, and BP by a second physician, neither of whom witnessed the tablet ingestion by the volunteers, nor provided with information on the nature of the test compounds. A third individual administered the tablets. The average baseline IOP of this group of 9 was 13.1 ± 0.6 mm Hg. Subsequent to sildenafil ingestion, IOP increased by 26% to 16.5 ± 0.8 mm Hg 60 min later (P < 0.005, as paired data), and returned to control values within 2 h. Both systolic and diastolic BP were significantly reduced by sildenafil ingestion. At the point of maximal systemic hypotension (90 min), the systolic and diastolic pressures declined by 15% and 13%, respectively. No significant changes in IOP or BP were recorded after

Mapping in-vivo optic nerve head strains caused by intraocular and intracranial pressures

NASA Astrophysics Data System (ADS)

Tran, H.; Grimm, J.; Wang, B.; Smith, M. A.; Gogola, A.; Nelson, S.; Tyler-Kabara, E.; Schuman, J.; Wollstein, G.; Sigal, I. A.

2017-02-01

Although it is well documented that abnormal levels of either intraocular (IOP) or intracranial pressure (ICP) can lead to potentially blinding conditions, such as glaucoma and papilledema, little is known about how the pressures actually affect the eye. Even less is known about potential interplay between their effects, namely how the level of one pressure might alter the effects of the other. Our goal was to measure in-vivo the pressure-induced stretch and compression of the lamina cribrosa due to acute changes of IOP and ICP. The lamina cribrosa is a structure within the optic nerve head, in the back of the eye. It is important because it is in the lamina cribrosa that the pressure-induced deformations are believed to initiate damage to neural tissues leading to blindness. An eye of a rhesus macaque monkey was imaged in-vivo with optical coherence tomography while IOP and ICP were controlled through cannulas in the anterior chamber and lateral ventricle, respectively. The image volumes were analyzed with a newly developed digital image correlation technique. The effects of both pressures were highly localized, nonlinear and non-monotonic, with strong interactions. Pressure variations from the baseline normal levels caused substantial stretch and compression of the neural tissues in the posterior pole, sometimes exceeding 20%. Chronic exposure to such high levels of biomechanical insult would likely lead to neural tissue damage and loss of vision. Our results demonstrate the power of digital image correlation technique based on non-invasive imaging technologies to help understand how pressures induce biomechanical insults and lead to vision problems.

Intraocular Pressure Control after Trabeculectomy, Phacotrabeculectomy and Phacoemulsification in a Hispanic Population.

PubMed

L Jung, Jennifer; Isida-Llerandi, Cristina G; Lazcano-Gomez, Gabriel; SooHoo, Jeffrey R; Kahook, Malik Y

2014-01-01

To compare the efficacy of different surgical strategies for intraocular pressure (IOP) control in Hispanic glaucoma patients with and without visually significant cataracts. Comparative retrospective consecutive case series. The charts of 153 consecutive patients with primary open angle glaucoma who underwent either trabeculectomy alone (n = 51), phacotrabeculectomy (n = 51), or phacoemulsification alone (n = 51) were reviewed to compare IOP control, the number of glaucoma medications required postoperatively, and the inci dence of surgical complications. Preoperative IOP was 17.5 ± 5.2 mm Hg in the trabe-culectomy group, 15.4 ± 4.5 mm Hg in the phacotrabeculectomy group and 13.9 ± 2.9 mm Hg in the phacoemulsification group (p < 0.001 for all comparisons). Mean IOP reduction from baseline was 4.2 ± 6.9 (24.6%) for the trabeculectomy group, 2.9 ± 5.0 (20.8%) for the phacotrabeculectomy group, and 0.9 ± 3.4 (6.5%) for the phacoemulsification group (p = 0.009). The number of IOP-lowering medications required postoperatively decreased significantly in all three groups (p = 0.001). The rate of early and late postoperative complications was similar between the trabeculectomy and phacotrabeculectomy groups and less for the phacoemulsification group. Trabeculectomy and phacotrabeculectomy are both viable surgical options for managing open angle glau coma. Both resulted in similar rates of success, IOP reduction, decrease in use of IOP-lowering medications and post operative complication rates. Phacoemulsification alone had a lower success rate and greater need for postoperative IOP-lowering medications compared to trabeculectomy alone or phacotrabeculectomy. Phacoemulsification alone may be a reasonable option for patients with visually significant cataract and lower baseline IOP. How to cite this article: Jung JL, Isida-Llerandi CG, Lazcano-Gomez G, SooHoo JR, Kahook MY. Intraocular Pressure Control after Trabeculectomy, Phacotrabeculectomy and Phaco

Intraocular Pressure Control after Trabeculectomy, Phacotrabeculectomy and Phacoemulsification in a Hispanic Population

PubMed Central

L Jung, Jennifer; Isida-Llerandi, Cristina G; Lazcano-Gomez, Gabriel; SooHoo, Jeffrey R

2014-01-01

ABSTRACT Purpose: To compare the efficacy of different surgical strategies for intraocular pressure (IOP) control in Hispanic glaucoma patients with and without visually significant cataracts. Design: Comparative retrospective consecutive case series. Methods: The charts of 153 consecutive patients with primary open angle glaucoma who underwent either trabeculectomy alone (n = 51), phacotrabeculectomy (n = 51), or phacoemulsification alone (n = 51) were reviewed to compare IOP control, the number of glaucoma medications required postoperatively, and the inci dence of surgical complications. Results: Preoperative IOP was 17.5 ± 5.2 mm Hg in the trabe-culectomy group, 15.4 ± 4.5 mm Hg in the phacotrabeculectomy group and 13.9 ± 2.9 mm Hg in the phacoemulsification group (p < 0.001 for all comparisons). Mean IOP reduction from baseline was 4.2 ± 6.9 (24.6%) for the trabeculectomy group, 2.9 ± 5.0 (20.8%) for the phacotrabeculectomy group, and 0.9 ± 3.4 (6.5%) for the phacoemulsification group (p = 0.009). The number of IOP-lowering medications required postoperatively decreased significantly in all three groups (p = 0.001). The rate of early and late postoperative complications was similar between the trabeculectomy and phacotrabeculectomy groups and less for the phacoemulsification group. Conclusion: Trabeculectomy and phacotrabeculectomy are both viable surgical options for managing open angle glau coma. Both resulted in similar rates of success, IOP reduction, decrease in use of IOP-lowering medications and post operative complication rates. Phacoemulsification alone had a lower success rate and greater need for postoperative IOP-lowering medications compared to trabeculectomy alone or phacotrabeculectomy. Phacoemulsification alone may be a reasonable option for patients with visually significant cataract and lower baseline IOP. How to cite this article: Jung JL, Isida-Llerandi CG, Lazcano-Gomez G, SooHoo JR, Kahook MY. Intraocular Pressure Control after

Toric Intraocular Lens Outcomes in Patients With Glaucoma.

PubMed

Brown, Reay H; Zhong, Le; Bozeman, Caroline W; Lynch, Mary G

2015-06-01

To report the outcomes of toric intraocular lens implantation in patients with glaucoma and corneal astigmatism. One hundred twenty-six eyes of 87 patients with glaucoma and corneal astigmatism that underwent cataract surgery with an AcrySof toric intraocular lens (Alcon Laboratories, Inc., Fort Worth, TX) implant were selected for this single-center, retrospective case series. Corrected distance visual acuity, intraocular pressure, and refractive astigmatism were measured in each eye preoperatively and postoperatively. Uncorrected distance visual acuity and toric alignment were measured postoperatively. The uncorrected distance visual acuity was 0.04 ± 0.08 logMAR (20/22 Snellen) for all eyes. Ninety-eight percent of all eyes achieved an uncorrected distance visual acuity of 20/40 or better, with 76% achieving 20/25 or better and 47% achieving 20/20. The corrected distance visual acuity for all eyes was 0.01 ± 0.03 logMAR (20/20.5 Snellen) postoperatively. The refractive cylinder improved from 1.47 ± 1.10 diopters preoperatively to 0.31 ± 0.37 diopters postoperatively. The residual refractive cylinder was 1.00 diopter or less in 97% of eyes, 0.75 diopters or less in 90% of eyes, and 0.50 diopters or less in 83% of eyes. Mean misalignment was 4.4° ± 5.1°. Intraocular pressure decreased by a mean of 2.3 ± 3.3 mm Hg following the surgery. Toric intraocular lenses can reliably reduce astigmatism and improve uncorrected vision in eyes with cataract and glaucoma. Copyright 2015, SLACK Incorporated.

Pathophysiology of intraocular pressure increase and glaucoma prevalence in thyroid eye disease: a mini-review.

PubMed

Haefliger, I O; von Arx, G; Pimentel, A-R

2010-04-01

The aim of this study was to assess the pathophysiological mechanisms leading to intraocular pressure (IOP) increase and to review the prevalence of glaucoma in thyroid eye disease (TED), an autoimmune reaction affecting extra-ocular muscles and intra-orbital content in thyrotoxicosis (Grave's disease, hyperthyroidism). We applied the modified Friedenswald's and Goldmann's equations to explain the mechanisms by which IOP increases in TED and gave a brief review of the literature. In TED, Friedenswald's equation explains the ultra-short term IOP increase observed when eyes deviate from their primary gaze position (eyeball compression by enlarged and infiltrated extra-ocular muscles). Goldmann's equation explains the long-term IOP increase seen in TED (episcleral venous pressure elevation secondary to intraorbital content and pressure increase). Most studies did not find a significant increase in glaucoma prevalence in patients with TED. In TED, glaucoma prevalence does not seem to be significantly increased and, from a pathophysiological standpoint, the long-term IOP increase is essentially due to episcleral venous pressure elevation. Copyright Georg Thieme Verlag KG Stuttgart . New York.

Effect of topical anesthetics on intraocular pressure and pachymetry.

PubMed

Montero, J A; Ruiz-Moreno, J M; Fernandez-Munoz, M; Rodriguez-Palacios, M I

2008-01-01

The determination of intraocular pressure (IOP) by noncontact tonometry (NCT) has been reported to be affected by central corneal thickness (CCT) and by the instillation of topical anesthetics. In order to determine the influence of topical anesthetics on CCT and IOP measured by NCT, 80 eyes from 49 patients were examined before and after the instillation of topical anesthetics. Average age was 55.3 years (SD 18.4, range 18 to 93). Twenty-eight patients were female and 21 were male. Average basal IOP was 16.1 mmHg (SD 5.2, range 8 to 35.3). IOP was 14.8 mmHg (SD 4.6, 7.4 to 32.4) (p=0.0005, Student t test for paired data) 5 minutes after topical anesthetics instillation. CCT averaged 541 micronm (SD 32, range 482 to 604) before topical anesthetic drops and 541 micronm (SD 32, 490 to 607, p=0.89, Student t test for paired data) 5 minutes after topical anesthetics instillation. The study confirms that the instillation of topical anesthetics causes a reduction in IOP. These changes do not seem to be associated with changes in CCT.

A Novel, Real-Time, In Vivo Mouse Retinal Imaging System

PubMed Central

Butler, Mark C.; Sullivan, Jack M.

2015-01-01

Purpose To develop an efficient, low-cost instrument for robust real-time imaging of the mouse retina in vivo, and assess system capabilities by evaluating various animal models. Methods Following multiple disappointing attempts to visualize the mouse retina during a subretinal injection using commercially available systems, we identified the key limitation to be inadequate illumination due to off axis illumination and poor optical train optimization. Therefore, we designed a paraxial illumination system for Greenough-type stereo dissecting microscope incorporating an optimized optical launch and an efficiently coupled fiber optic delivery system. Excitation and emission filters control spectral bandwidth. A color coupled-charged device (CCD) camera is coupled to the microscope for image capture. Although, field of view (FOV) is constrained by the small pupil aperture, the high optical power of the mouse eye, and the long working distance (needed for surgical manipulations), these limitations can be compensated by eye positioning in order to observe the entire retina. Results The retinal imaging system delivers an adjustable narrow beam to the dilated pupil with minimal vignetting. The optic nerve, vasculature, and posterior pole are crisply visualized and the entire retina can be observed through eye positioning. Normal and degenerative retinal phenotypes can be followed over time. Subretinal or intraocular injection procedures are followed in real time. Real-time, intravenous fluorescein angiography for the live mouse has been achieved. Conclusions A novel device is established for real-time viewing and image capture of the small animal retina during subretinal injections for preclinical gene therapy studies. PMID:26551329

A Novel, Real-Time, In Vivo Mouse Retinal Imaging System.

PubMed

Butler, Mark C; Sullivan, Jack M

2015-11-01

To develop an efficient, low-cost instrument for robust real-time imaging of the mouse retina in vivo, and assess system capabilities by evaluating various animal models. Following multiple disappointing attempts to visualize the mouse retina during a subretinal injection using commercially available systems, we identified the key limitation to be inadequate illumination due to off axis illumination and poor optical train optimization. Therefore, we designed a paraxial illumination system for Greenough-type stereo dissecting microscope incorporating an optimized optical launch and an efficiently coupled fiber optic delivery system. Excitation and emission filters control spectral bandwidth. A color coupled-charged device (CCD) camera is coupled to the microscope for image capture. Although, field of view (FOV) is constrained by the small pupil aperture, the high optical power of the mouse eye, and the long working distance (needed for surgical manipulations), these limitations can be compensated by eye positioning in order to observe the entire retina. The retinal imaging system delivers an adjustable narrow beam to the dilated pupil with minimal vignetting. The optic nerve, vasculature, and posterior pole are crisply visualized and the entire retina can be observed through eye positioning. Normal and degenerative retinal phenotypes can be followed over time. Subretinal or intraocular injection procedures are followed in real time. Real-time, intravenous fluorescein angiography for the live mouse has been achieved. A novel device is established for real-time viewing and image capture of the small animal retina during subretinal injections for preclinical gene therapy studies.

Red-free light for measurement of intraocular pressure using Goldmann applanation tonometer without fluorescein.

PubMed

Ghoneim, Ehab M

2014-01-01

To evaluate the use of red-free light for the measurement of intraocular pressure (IOP) using a Goldmann applanation tonometer without fluorescein. This cross-sectional study was carried out on 500 eyes in 250 patients attending the Ophthalmology Outpatient Clinic at Suez Canal University Hospital. The IOP was measured using a Goldmann applanation tonometer mounted on a Haag-Streit slit-lamp. The measurements were performed first using red-free light without fluorescein. Then the measurements were repeated with cobalt blue light and topical fluorescein on the same eyes. The mean IOP was 15.23 ± 3.3 (SD) mm Hg using the red-free light without fluorescein, whereas it was 15.78 ± 3.7 (SD) mm Hg when measured using cobalt blue light after the application of fluorescein to the conjunctival sac. This difference was not statistically significant. Measurement of IOP with a Goldmann applanationtonometer with red-free light and without the use of fluorescein is simple, saves time, and gives an accurate IOP measurement relative to the traditional measurement technique with cobalt blue light and topical fluorescein.

Pharmacokinetic basis for nonadditivity of intraocular pressure lowering in timolol combinations.

PubMed

Lee, V H; Luo, A M; Li, S Y; Podder, S K; Chang, J S; Ohdo, S; Grass, G M

1991-10-01

The authors determined whether the ocular absorption of topically applied timolol in the pigmented rabbit was affected significantly by coadministration with either pilocarpine or epinephrine in the same drop to explain the nonadditivity in intraocular pressure lowering (IOP) seen clinically. They instilled 25 microliters of 0.65% timolol maleate solution (equivalent to 0.5% timolol), both in the presence and absence of 2.6% pilocarpine nitrate or 1% epinephrine bitartrate, into pigmented rabbit eyes. The time course of timolol concentration in the conjunctiva, anterior sclera, corneal epithelium, corneal stroma, aqueous humor, iris-ciliary body, and lens was monitored for 360 min by using reversed-phase high-performance liquid chromatography. The area under the timolol concentration-time curve in all but one of the anterior segment tissues was reduced by 20-50% (mean, 40%) when timolol was coadministered with pilocarpine and by 20-70% (mean, 42%) when timolol was coadministered with epinephrine. Such an effect was not a result of alterations in corneal permeability or aqueous humor turnover rate, nor was it related to the extent of systemic absorption caused by pilocarpine and epinephrine. Rather, the reduction in ocular timolol absorption may have been caused by the accelerated washout of timolol by tears stimulated by the coadministered drugs and, to a lesser extent, by the loss of timolol through binding to the increased amount of tear proteins induced by the coadministered drugs. Thus, the nonadditivity in IOP lowering from timolol-pilocarpine and timolol-epinephrine combinations is probably caused by changes in precorneal timolol clearance.

Effect of Gradual Onset +G(sub z) Acceleration on Rate of Visual Field Collapse and Intraocular Pressure

NASA Technical Reports Server (NTRS)

Haines, Richard F.; Rositano, Salvador A.; Greenleaf, John E.

1976-01-01

The mechanisms that control the size of the visual field during positive acceleration are poorly understood, but involve mainly the arterial blood pressure at the eye level and intraocular pressure (IOP) (3). Fluid and electrolyte shifts that occur in the general circulation during acceleration may well influence the rate at which the visual field collapses. This could, in turn, suggest the relative influences that arterial blood pressure, IOP, and various compensatory mechanisms have upon acceleration tolerance. Such knowledge could also be of use in the design and development of protective techniques for use in the acceleration environment. The present investigation was performed to study blood withdrawal (hypovolemia) and subsequent reinfusion, oral fluid replacement upon IOP, and the rate at which the visual field collapses during gradual onset +G(sub z) acceleration (0.5 G/min).

Reliable intraocular pressure measurement using automated radio-wave telemetry

PubMed Central

Paschalis, Eleftherios I; Cade, Fabiano; Melki, Samir; Pasquale, Louis R; Dohlman, Claes H; Ciolino, Joseph B

2014-01-01

Purpose To present an autonomous intraocular pressure (IOP) measurement technique using a wireless implantable transducer (WIT) and a motion sensor. Methods The WIT optical aid was implanted within the ciliary sulcus of a normotensive rabbit eye after extracapsular clear lens extraction. An autonomous wireless data system (AWDS) comprising of a WIT and an external antenna aided by a motion sensor provided continuous IOP readings. The sensitivity of the technique was determined by the ability to detect IOP changes resulting from the administration of latanoprost 0.005% or dorzolamide 2%, while the reliability was determined by the agreement between baseline and vehicle (saline) IOP. Results On average, 12 diurnal and 205 nocturnal IOP measurements were performed with latanoprost, and 26 diurnal and 205 nocturnal measurements with dorzolamide. No difference was found between mean baseline IOP (13.08±2.2 mmHg) and mean vehicle IOP (13.27±2.1 mmHg) (P=0.45), suggesting good measurement reliability. Both antiglaucoma medications caused significant IOP reduction compared to baseline; latanoprost reduced mean IOP by 10% (1.3±3.54 mmHg; P<0.001), and dorzolamide by 5% (0.62±2.22 mmHg; P<0.001). Use of latanoprost resulted in an overall twofold higher IOP reduction compared to dorzolamide (P<0.001). Repeatability was ±1.8 mmHg, assessed by the variability of consecutive IOP measurements performed in a short period of time (≤1 minute), during which the IOP is not expected to change. Conclusion IOP measurements in conscious rabbits obtained without the need for human interactions using the AWDS are feasible and provide reproducible results. PMID:24531415

Reliable intraocular pressure measurement using automated radio-wave telemetry.

PubMed

Paschalis, Eleftherios I; Cade, Fabiano; Melki, Samir; Pasquale, Louis R; Dohlman, Claes H; Ciolino, Joseph B

2014-01-01

To present an autonomous intraocular pressure (IOP) measurement technique using a wireless implantable transducer (WIT) and a motion sensor. The WIT optical aid was implanted within the ciliary sulcus of a normotensive rabbit eye after extracapsular clear lens extraction. An autonomous wireless data system (AWDS) comprising of a WIT and an external antenna aided by a motion sensor provided continuous IOP readings. The sensitivity of the technique was determined by the ability to detect IOP changes resulting from the administration of latanoprost 0.005% or dorzolamide 2%, while the reliability was determined by the agreement between baseline and vehicle (saline) IOP. On average, 12 diurnal and 205 nocturnal IOP measurements were performed with latanoprost, and 26 diurnal and 205 nocturnal measurements with dorzolamide. No difference was found between mean baseline IOP (13.08±2.2 mmHg) and mean vehicle IOP (13.27±2.1 mmHg) (P=0.45), suggesting good measurement reliability. Both antiglaucoma medications caused significant IOP reduction compared to baseline; latanoprost reduced mean IOP by 10% (1.3±3.54 mmHg; P<0.001), and dorzolamide by 5% (0.62±2.22 mmHg; P<0.001). Use of latanoprost resulted in an overall twofold higher IOP reduction compared to dorzolamide (P<0.001). Repeatability was ±1.8 mmHg, assessed by the variability of consecutive IOP measurements performed in a short period of time (≤1 minute), during which the IOP is not expected to change. IOP measurements in conscious rabbits obtained without the need for human interactions using the AWDS are feasible and provide reproducible results.

Regulation of choroidal blood flow during combined changes in intraocular pressure and arterial blood pressure.

PubMed

Polska, Elzbieta; Simader, Christian; Weigert, Günter; Doelemeyer, Arno; Kolodjaschna, Julia; Scharmann, Ole; Schmetterer, Leopold

2007-08-01

To test the hypothesis that human choroidal blood flow (ChBF) may depend, not only on ocular perfusion pressure (OPP), but also on absolute mean arterial pressure (MAP) and intraocular pressure (IOP). There were two study days in an open design. On the first day, OPP was varied by elevating IOP during a squatting-induced increase in MAP (28 subjects). On the second day, only the IOP was increased (17 subjects). IOP was raised in stepwise increments by using the suction cup Subfoveal ChBF (laser Doppler flowmetry), MAP, and IOP were assessed, and OPP was calculated as (2/3)(MAP - IOP). For correlation analysis, data from all subjects were pooled according to IOP and MAP, and correlation analyses were performed. When data from study day 1 were grouped according to IOP, no correlation was observed between ChBF and MAP; but ChBFs were lower, the higher the IOP (P < 0.001). When data were grouped according to MAP, a significant correlation was found between ChBF and IOP (P < 0.001), but correlations were independent of MAP. When data of study day 2 were pooled according to IOP, a correlation between ChBF and OPP was seen only at IOP > 40 mm Hg (P < 0.05). The data confirm previously published observations that the choroid shows some autoregulatory capacity during changes in OPP. In addition, the data indicate that the choroid regulates its blood flow better during exercise-induced changes in MAP than during an experimental increase in IOP.

Assessment of intraocular pressure sensing using an implanted reflective flexible membrane

NASA Astrophysics Data System (ADS)

Nazarov, Andrey; Knyazer, Boris; Lifshitz, Tova; Schvartzman, Mark; Abdulhalim, Ibrahim

2017-04-01

Glaucoma is a neurodegenerative condition that is the leading cause of irreversible blindness worldwide. Elevated intraocular pressure (IOP) is the main cause for the development of the disease. The symptoms of this form, such as deterioration of vision and scotomas (loss of visual fields), appear in the latter stages of the disease. Therefore, an IOP monitoring device is needed for better, simpler, and faster diagnosis, and to enable a fast treatment response. We present a theoretical assessment as well as preliminary experimental results of a simple approach for easy, optical, IOP self-monitoring. It is based on a polydimethylsiloxane membrane coated with a reflective layer and a Hartmann-Shack wavefront sensor. Nearly linear correlation is found between membrane deformation and Zernike coefficients representing defocus primary spherical aberration, with high sensitivity and negligible dependence on the measurement distance. The proposed device is expected to provide an accurate IOP measurement resolution of less than ±0.2 mm Hg with a pressure dependence on working distances <0.7 mm Hg/cm for a thick membrane; the corresponding values for a thin membrane are ±0.45 mm Hg and <0.6 mm Hg/cm, respectively, at typical IOP values-up to 40 mm Hg.

Intraocular pressure is sensitive to cumulative and instantaneous mental workload.

PubMed

Vera, Jesús; Jiménez, Raimundo; García, José Antonio; Cárdenas, David

2017-04-01

We used a repeated-measures design to assess the impact of mental-task complexity on intraocular pressure (IOP). Fourteen participants performed three continuous 11-min blocks of a mental-workload task (3-back) and an oddball version of this task. Also, heart-rate variability (HRV), cognitive-performance scores, and subjective measure of mental load (NASA-TLX) were determined. IOP was taken before each block and afterwards as well as after recovery from mental tasks. We found that IOP increased during heavy mental workloads (p < 0.01). Consistent with this finding, the autonomic control (HRV) and the cognitive performance were significantly lower (p < 0.045, and p < 0.01, respectively), and the NASA-TLX scores were higher during the 3-back task (p < 0.01). We conclude that IOP is sensitive to mental workload, and it could provide a novel neuroergonomic tool to assess mental workload. Our study highlights a potential association between IOP and the nervous system's state of activation. Copyright © 2016 Elsevier Ltd. All rights reserved.

Stem Cells in the Trabecular Meshwork for Regulating Intraocular Pressure.

PubMed

Yun, Hongmin; Zhou, Yi; Wills, Andrew; Du, Yiqin

2016-06-01

Intraocular pressure (IOP) is still the main treatment target for glaucoma. Outflow resistance mainly exists at the trabecular meshwork (TM) outflow pathway, which is responsible for IOP regulation. Changes of TM cellularity and TM extracellular matrix turnover may play important roles in IOP regulation. In this article, we review basic anatomy and physiology of the outflow pathway and TM stem cell characteristics regarding the location, isolation, identification and function. TM stem cells are localized at the insert region of the TM and are label-retaining in vivo. They can be isolated by side-population cell sorting, cloning culture, or sphere culture. TM stem cells are multipotent with the ability to home to the TM region and differentiate into TM cells in vivo. Other stem cell types, such as adipose-derived stem cells, mesenchymal stem cells and induced pluripotent stem cells have been discovered for TM cell differentiation and TM regeneration. We also review glaucomatous animal models, which are suitable to study stem cell-based therapies for TM regeneration.

Stem Cells in the Trabecular Meshwork for Regulating Intraocular Pressure

PubMed Central

Yun, Hongmin; Zhou, Yi; Wills, Andrew

2016-01-01

Abstract Intraocular pressure (IOP) is still the main treatment target for glaucoma. Outflow resistance mainly exists at the trabecular meshwork (TM) outflow pathway, which is responsible for IOP regulation. Changes of TM cellularity and TM extracellular matrix turnover may play important roles in IOP regulation. In this article, we review basic anatomy and physiology of the outflow pathway and TM stem cell characteristics regarding the location, isolation, identification and function. TM stem cells are localized at the insert region of the TM and are label-retaining in vivo. They can be isolated by side-population cell sorting, cloning culture, or sphere culture. TM stem cells are multipotent with the ability to home to the TM region and differentiate into TM cells in vivo. Other stem cell types, such as adipose-derived stem cells, mesenchymal stem cells and induced pluripotent stem cells have been discovered for TM cell differentiation and TM regeneration. We also review glaucomatous animal models, which are suitable to study stem cell-based therapies for TM regeneration. PMID:27183473

Does postmenopausal hormone replacement therapy affect intraocular pressure?

PubMed

Abramov, Yoram; Borik, Sharon; Yahalom, Claudia; Fatum, Muhammad; Avgil, Gadiel; Brzezinski, Amnon; Banin, Eyal

2005-08-01

To assess the effects of postmenopausal hormone replacement therapy (HRT) on intraocular pressure (IOP). This was a cross-sectional controlled study, including 107 women aged 60 to 80 years receiving HRT and 107 controls who have never received HRT. All subjects underwent IOP assessment and funduscopic photography for cup-to-disc (C/D) ratios, and completed questionnaires regarding personal and family history of glaucoma, hormone replacement therapy, lifetime estrogen and progesterone exposure, and cardiovascular risk factors. Main Outcome Measures included IOP, prevalence of increased IOP, and C/D ratios. The groups did not differ in mean IOP (15.3 versus 15.3 mm Hg), mean vertical (0.18 versus 0.21) and horizontal (0.17 versus 0.14) C/D ratios, and in prevalence of increased IOP (15% versus 14%), C/D ratio (7% versus 7%), or glaucoma (9% versus 11%). A personal history of ischemic heart disease was the only risk factor associated with increased IOP (O.R. = 4.63, P = 0.003). Lifetime estrogen and progesterone exposure, including pregnancies, deliveries, menstruation years, and the use of oral contraceptives did not significantly affect the risk for increased IOP. Hormone replacement therapy and lifetime estrogen and progesterone exposure do not seem to affect IOP or the risk for increased IOP. A personal history of ischemic heart disease may be associated with a higher risk for this disorder.

Diurnal variations in axial length, choroidal thickness, intraocular pressure, and ocular biometrics.

PubMed

Chakraborty, Ranjay; Read, Scott A; Collins, Michael J

2011-07-11

To investigate the pattern of diurnal variations in axial length (AL), choroidal thickness, intraocular pressure (IOP), and ocular biometrics over 2 consecutive days. Measurements of ocular biometrics and IOP were collected for 30 young adult subjects (15 myopes, 15 emmetropes) at 10 different times over 2 consecutive days. Five sets of measurements were collected each day at approximately 3-hour intervals, with the first measurement taken at ~9 AM and final measurement at ~9 PM. AL underwent significant diurnal variation (P < 0.0001) that was consistently observed across the 2 measurement days. The longest AL was typically observed at the second measurement session (mean time, 12:26) and the shortest AL at the final session of each day (mean time, 21:06). The mean diurnal change in AL was 0.032 ± 0.018 mm. Choroidal thickness underwent significant diurnal variation (mean change, 0.029 ± 0.016 mm; P < 0.001) and varied approximately in antiphase to the AL changes. Significant diurnal variations were also found in vitreous chamber depth (VCD; mean change, 0.06 ± 0.029 mm; P < 0.0001) and IOP (mean change, 3.54 ± 0.84 mm Hg; P < 0.0001). A positive association was found between the variations of AL and IOP (r(2) = 0.17, P < 0.0001) and AL and VCD (r(2) = 0.31, P < 0.0001) and a negative association between AL and choroidal thickness (r(2) = 0.13, P < 0.0001). There were no significant differences in the magnitude and timing of diurnal variations associated with refractive error. Significant diurnal variations in AL, choroidal thickness, and IOP were consistently observed over 2 consecutive days of testing.

Comparison of sugammadex and neostigmine-atropine on intraocular pressure and postoperative effects.

PubMed

Hakimoğlu, Sedat; Tuzcu, Kasım; Davarcı, Işıl; Karcıoğlu, Murat; Ayhan Tuzcu, Esra; Hancı, Volkan; Aydın, Suzan; Kahraman, Hilal; Elbeyli, Ahmet; Turhanoğlu, Selim

2016-02-01

During surgery, changes in intraocular pressure (IOP) can be observed resulting from several factors, such as airway manipulations and drugs used. We aimed to investigate the effects of sugammadex and neostigmine on IOP, hemodynamic parameters, and complications after extubation. Our study comprised 60 patients, aged 18-65 years, with a risk status of the American Society of Anesthesiologists I-II who underwent arthroscopic surgery under general anesthesia. The patients were randomly assigned into two groups. At the end of the surgery, the neuromuscular block was reversed using neostigmine (50 μg/kg) plus atropine (15 μg/kg) in Group 1, and sugammadex (4 mg/kg) in Group 2. Neuromuscular blockade was monitored using acceleromyography and a train-of-four mode of stimulation. IOP was measured before induction and at 30 seconds, 2 minutes, and 10 minutes after extubation. A Tono-Pen XL applanation tonometer was used to measure IOP. This showed that elevation in IOP of patients reversed using sugammadex was similar to that recorded in patients reversed using neostigmine-atropine. When heart rate was compared, there was a significant difference between basal values and those obtained at 30 seconds and 10 minutes after extubation in the neostigmine-atropine group. Extubation time (time from withdrawal of anesthetic gas to extubation) was significantly shorter in the sugammadex group (p = 0.003) than in the neostigmine-atropine group. The postextubation IOP values of the sugammadex group were similar to the neostigmine-atropine group. Extubation time (time from withdrawal of anesthetic gas to extubation) was significantly shorter in the sugammadex group (p = 0.003) than in the neostigmine-atropine group. Copyright © 2016. Published by Elsevier Taiwan.

Manipulation of intraocular pressure for studying the effects on accommodation.

PubMed

He, Lin; Wendt, Mark; Glasser, Adrian

2012-09-01

A reliable experimental system in which IOP can be manipulated or a rapid IOP change can be induced while simultaneously and continuously measuring IOP and the ocular accommodative changes would be useful for understanding the physiological effect of intraocular pressure (IOP) on the accommodative mechanism. In this study, an IOP perfusion and recording system was developed and tested using 13 enucleated pig eyes. The vitreous chamber of the pig eyes was cannulated with a needle connected to two fluid reservoirs at different heights. One reservoir was set to achieve one of three baseline pressures of 5.5 mmHg, 13.0 mmHg and 20.5 mmHg. The other reservoir was moved to achieve pressures of 1.5 mmHg, 3.0 mmHg, 4.5 mmHg and 6.0 mmHg higher than the baseline pressure. The height differential between the reservoirs determined the amplitude of IOP changes. Rapid IOP changes were induced by switching the reservoirs with a solenoid pinch-valve. Two needles, one each attached to a pressure transducer were inserted into the anterior chamber and vitreous chamber respectively. Custom developed software was used to measure the anterior chamber pressure and vitreous chamber pressure at 80 Hz. A high-resolution continuous A-scan ultrasound biometer (CUB) was used to dynamically measure changes in ocular biometry including anterior chamber depth (ACD), lens thickness (LT) and vitreous chamber depth (VCD) while the vitreous chamber pressure was manipulated. The changes in ACD, LT and VCD were analyzed as a function of the pressure change. Perfusion-induced axial biometric changes were quantified by the slopes of linear regression relationships. Both anterior chamber pressure and vitreous chamber pressure changed relatively systematically with the induced vitreous chamber pressure changes (anterior chamber: y = 0.863x + 0.030, r(2) = 0.983; vitreous chamber: y = 0.883x + 0.009, r(2) = 0.981). At perfusion pressures of 5.5, 13.0 and 20.5 mmHg, the slopes for ACD

Baseline Intraocular Pressure Is Associated With Subjective Sensitivity to Physical Exertion in Young Males.

PubMed

Vera, Jesús; Jiménez, Raimundo; García, José Antonio; Perales, José Cesar; Cárdenas, David

2018-03-01

The purposes of this study were to (a) investigate the effect of physical effort (cycling for 60 min at 60 ± 5% of individually computed reserve heart-rate capacity), combined with 2 different levels of cognitive demand (2-back, oddball), on intraocular pressure (IOP) and subjective judgments of perceived exertion (ratings of perceived exertion [RPE]), affect (Affective Valence subscale of the Self-Assessment Manikin [SAM]), and mental workload (National Aeronautics and Space Administration Task Load Index [NASA-TLX]); and (b) ascertain whether baseline IOP, measured before exercise, is associated with individual differences in subjective assessments of effort and affective response during exercise. Seventeen participants (M age = 23.28 ± 2.37 years) performed 2 physical/cognitive dual tasks, matched in physical demand but with different mental requirements (2-back, oddball). We assessed IOP before exercise, after 2 min of active recovery, and after 15 min of passive recovery, and we also collected RPE and SAM measures during the sessions (28 measurement points). We used NASA-TLX and cognitive performance as checks of the mental manipulation. (a) Intraocular pressure increased after concomitant physical/mental effort, with the effect reaching statistical significance after the 2-back task (p = .002, d = 0.35) but not after the oddball condition (p = .092, d = 0.29). (b) Baseline IOP was associated with subjective sensitivity to effort and showed statistical significance for the oddball condition (p = .03, ƞ p 2  = .622) but not for the 2-back task (F < 1). Results suggest a relationship between IOP and physical/cognitive effort, which could have implications for the management of glaucoma. Additionally, a rapid measure of IOP could be used as a marker of individual effort sensitivity in applied settings.

New intraocular pressure measurement method using reflected pneumatic pressure from cornea deformed by air puff of ring-type nozzle.

PubMed

Kim, Hyung Jin; Seo, Yeong Ho; Kim, Byeong Hee

2017-01-01

In this study, a non-contact type intraocular pressure (IOP) measuring system using reflected pneumatic pressure is proposed to overcome the disadvantages of existing measurement systems. A ring-type nozzle, a key component in the proposed system, is designed via computational fluid analysis. It predicts the reflected pneumatic pressure based on the nozzle exit angle and inner and outer diameters of the nozzle, which are 30°, 7 mm, and 9 mm, respectively. Performance evaluation is conducted using artificial eyes fabricated using polydimethylsiloxane with the specifications of human eyes. The IOP of the fabricated artificial eyes is adjusted to 10, 30, and 50 mm Hg, and the reflected pneumatic pressure is measured as a function of the distance between the ring-type nozzle and artificial eye. The measured reflected pneumatic pressure is high when the measurement distance is short and eye pressure is low. The cornea of an artificial eye is significantly deformed at a low IOP, and the applied pneumatic pressure is more concentrated in front of the ring-type nozzle because of the deformed cornea. Thus, the reflected pneumatic pressure at a low IOP has more inflows into the pressure sensor inserted inside the nozzle. The sensitivity of the output based on the IOP at measurement distances between 3-5 mm is -0.0027, -0.0022, -0.0018, -0.0015, and -0.0012. Sensitivity decreases as the measurement distance increases. In addition, the reflected pneumatic pressure owing to the misalignment at the measurement distances of 3-5 mm is not affected within a range of 0.5 mm. Therefore, the measurement range is acceptable up to a 1 mm diameter from the center of an artificial eye. However, the accuracy gradually decreases as the reflected pneumatic pressure from a misalignment of 1 mm or more decreases by 26% or more.

New intraocular pressure measurement method using reflected pneumatic pressure from cornea deformed by air puff of ring-type nozzle

PubMed Central

Kim, Hyung Jin; Seo, Yeong Ho

2017-01-01

In this study, a non-contact type intraocular pressure (IOP) measuring system using reflected pneumatic pressure is proposed to overcome the disadvantages of existing measurement systems. A ring-type nozzle, a key component in the proposed system, is designed via computational fluid analysis. It predicts the reflected pneumatic pressure based on the nozzle exit angle and inner and outer diameters of the nozzle, which are 30°, 7 mm, and 9 mm, respectively. Performance evaluation is conducted using artificial eyes fabricated using polydimethylsiloxane with the specifications of human eyes. The IOP of the fabricated artificial eyes is adjusted to 10, 30, and 50 mm Hg, and the reflected pneumatic pressure is measured as a function of the distance between the ring-type nozzle and artificial eye. The measured reflected pneumatic pressure is high when the measurement distance is short and eye pressure is low. The cornea of an artificial eye is significantly deformed at a low IOP, and the applied pneumatic pressure is more concentrated in front of the ring-type nozzle because of the deformed cornea. Thus, the reflected pneumatic pressure at a low IOP has more inflows into the pressure sensor inserted inside the nozzle. The sensitivity of the output based on the IOP at measurement distances between 3–5 mm is -0.0027, -0.0022, -0.0018, -0.0015, and -0.0012. Sensitivity decreases as the measurement distance increases. In addition, the reflected pneumatic pressure owing to the misalignment at the measurement distances of 3–5 mm is not affected within a range of 0.5 mm. Therefore, the measurement range is acceptable up to a 1 mm diameter from the center of an artificial eye. However, the accuracy gradually decreases as the reflected pneumatic pressure from a misalignment of 1 mm or more decreases by 26% or more. PMID:29216189

Determinants and Heritability of Intraocular Pressure and Cup-to-Disc Ratio in a Defined Older Population

PubMed Central

Chang, Ta C.; Congdon, Nathan G.; Wojciechowski, Robert; Muñoz, Beatriz; Gilbert, Donna; Chen, Ping; Friedman, David S.; West, Sheila K.

2011-01-01

Purpose To investigate the heritability of intraocular pressure (IOP) and cup-to-disc ratio (CDR) in an older well-defined population. Design Family-based cohort study. Participants Through the population-based Salisbury Eye Evaluation study, we recruited 726 siblings (mean age, 74.7 years) in 284 sibships. Methods Intraocular pressure and CDR were measured bilaterally for all participants. The presence or absence of glaucoma was determined by a glacuoma specialist for all probands on the basis of visual field, optic nerve appearance, and history. The heritability of IOP was calculated as twice the residual between-sibling correlation of IOP using linear regression and generalized estimating equations after adjusting for age, gender, mean arterial pressure, race, self-reported diabetes status, and history of systemic steroid use. The heritability of CDR was calculated using the same model and adjustments as above, while also adjusting for IOP. Main Outcome Measures Heritability and determinants of IOP and CDR, and impact of siblings’ glaucoma status on IOP and CDR. Results We estimated the heritability to be 0.29 (95% confidence interval [CI], 0.12–0.46) for IOP and 0.56 (95% CI, 0.35–0.76) for CDR in this population. Mean IOP in siblings of glaucomatous probands was statistically significantly higher than in siblings of normal probands (mean difference, 1.02 mmHg; P = 0.017). The mean CDR in siblings of glaucomatous probands was 0.07 (or 19%) larger than in siblings of glaucoma suspect referrals (P = 0.045) and siblings of normal probands (P = 0.004). Conclusions In this elderly population, we found CDR to be highly heritable and IOP to be moderately heritable. On average, siblings of glaucoma patients had higher IOPs and larger CDRs than siblings of nonglaucomatous probands. PMID:15939473

Comparison of intra-ocular pressure changes with liquid or flat applanation interfaces in a femtosecond laser platform.

PubMed

Williams, G P; Ang, H P; George, B L; Liu, Y C; Peh, G; Izquierdo, L; Tan, D T; Mehta, J S

2015-10-06

Cataract surgery is the most common surgical procedure and femtosecond laser assisted cataract surgery (FLACS) has gained increased popularity. FLACS requires the application of a suction device to stabilize the laser head and focus the laser beam accurately. This may cause a significant escalation in intra-ocular pressure (IOP), which poses potential risks for patients undergoing cataract surgery. In this study we aimed to assess the effect of the Ziemer LDV Z8 femtosecond cataract machine on IOP. We demonstrated through a porcine model that IOP was significantly higher with a flat interface but could be abrogated by reducing surgical compression and vacuum. Pressure was lower with a liquid interface, and further altering angulation of the laser arm could reduce the IOP to 36 mmHg. A pilot series in patients showed comparable pressure rises with the porcine model (30 mmHg). These strategies may improve the safety profile in patients vulnerable to high pressure when employing FLACS with the Ziemer LDV Z8.

Intraocular pressure and cerebral oxygenation during prolonged headward acceleration.

PubMed

Eiken, Ola; Keramidas, Michail E; Taylor, Nigel A S; Grönkvist, Mikael

2017-01-01

Supra-tolerance head-to-foot directed gravitoinertial load (+Gz) typically induces a sequence of symptoms/signs, including loss of: peripheral vision-central vision-consciousness. The risk of unconsciousness is greater when anti-G-garment failure occurs after prolonged rather than brief exposures, presumably because, in the former condition, mental signs are not consistently preceded by impaired vision. The aims were to investigate if prolonged exposure to moderately elevated +Gz reduces intraocular pressure (IOP; i.e., improves provisions for retinal perfusion), or the cerebral anoxia reserve. Subjects were exposed to 4-min +Gz plateaux either at 2 and 3 G (n = 10), or at 4 and 5 G (n = 12). Measurements included eye-level mean arterial pressure (MAP), oxygenation of the cerebral frontal cortex, and at 2 and 3 G, IOP. IOP was similar at 1 (14.1 ± 1.6 mmHg), 2 (14.0 ± 1.6 mmHg), and 3 G (14.0 ± 1.6 mmHg). During the G exposures, MAP exhibited an initial prompt drop followed by a partial recovery, end-exposure values being reduced by ≤30 mmHg. Cerebral oxygenation showed a similar initial drop, but without recovery, and was followed by either a plateau or a further slight decrement to a minimum of about -14 μM. Gz loading did not affect IOP. That cerebral oxygenation remained suppressed throughout these G exposures, despite a concomitant partial recovery of MAP, suggests that the increased risk of unconsciousness upon G-garment failure after prolonged +Gz exposure is due to reduced cerebral anoxia reserve.

Time course of optical quality and intraocular scattering after refractive lenticule extraction.

PubMed

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

2013-01-01

To assess the time course of optical quality and intraocular scattering in relation to visual acuity after femtosecond lenticule extraction (FLEx) for the correction of myopia. This study evaluated 36 eyes of 36 patients with spherical equivalents of -4.38±1.53 D [mean ± standard deviation] who underwent FLEx. Before surgery, and 1 week and 1, 3 and 6 months after surgery, we assessed the modulation transfer function (MTF) cutoff frequency, Strehl ratio, objective scattering index (OSI), and OQAS values (OVs), using a double-pass instrument. We also investigated the relationship of the OSI with corrected distance visual acuity (CDVA) preoperatively and postoperatively. The mean changes in MTF cutoff frequency, Strehl ratio, OSI, OV100%, OV20%, and OV9% preoperatively and 6 months postoperatively were -5.51 ± 15.01, -0.03 ± 0.07, 0.35 ± 0.83, -0.17 ± 0.48, -0.14 ± 0.38, and -0.09 ± 0.22, respectively. We found no significant preoperative correlation between the OSI and logMAR CDVA (Spearman rank correlation coefficient r = 0.068, p = 0.69), and modest, but significant correlations 1 week and 1, 3, and 6 months postoperatively (r = 0.572, r = 0.562, r = 0.542, r = 0.540, p<0.001, respectively). FLEx induced a transient decrease in optical quality in association with an increase in intraocular scattering in the early postoperative period, possibly due to mild interface haze formation, but gradually recovered with time. It is suggested that this transient degradation in optical quality related to an increase in the intraocular scattering may result in a slight delay of CDVA recovery in the early postoperative period.

Dynamic, in vivo, real-time detection of retinal oxidative status in a model of elevated intraocular pressure using a novel, reversibly responsive, profluorescent nitroxide probe.

PubMed

Rayner, Cassie L; Gole, Glen A; Bottle, Steven E; Barnett, Nigel L

2014-12-01

Changes to the redox status of biological systems have been implicated in the pathogenesis of a wide variety of disorders including cancer, Ischemia-reperfusion (I/R) injury and neurodegeneration. In times of metabolic stress e.g. ischaemia/reperfusion, reactive oxygen species (ROS) production overwhelms the intrinsic antioxidant capacity of the cell, damaging vital cellular components. The ability to quantify ROS changes in vivo, is therefore essential to understanding their biological role. Here we evaluate the suitability of a novel reversible profluorescent probe containing a redox-sensitive nitroxide moiety (methyl ester tetraethylrhodamine nitroxide, ME-TRN), as an in vivo, real-time reporter of retinal oxidative status. The reversible nature of the probe's response offers the unique advantage of being able to monitor redox changes in both oxidizing and reducing directions in real time. After intravitreal administration of the ME-TRN probe, we induced ROS production in rat retina using an established model of complete, acute retinal ischaemia followed by reperfusion. After restoration of blood flow, retinas were imaged using a Micron III rodent fundus fluorescence imaging system, to quantify the redox-response of the probe. Fluorescent intensity declined during the first 60 min of reperfusion. The ROS-induced change in probe fluorescence was ameliorated with the retinal antioxidant, lutein. Fluorescence intensity in non-Ischemia eyes did not change significantly. This new probe and imaging technology provide a reversible and real-time response to oxidative changes and may allow the in vivo testing of antioxidant therapies of potential benefit to a range of diseases linked to oxidative stress. Copyright © 2014 Elsevier Ltd. All rights reserved.

Phakic Intraocular Lenses

MedlinePlus

... Implants and Prosthetics Phakic Intraocular Lenses Phakic Intraocular Lenses Share Tweet Linkedin Pin it More sharing options Linkedin Pin it Email Print Phakic intraocular lenses are new devices used to correct nearsightedness. These ...

Hypobaric hypoxia: effects on intraocular pressure and corneal thickness.

PubMed

Nebbioso, Marcella; Fazio, Stefano; Di Blasio, Dario; Pescosolido, Nicola

2014-01-01

The purpose of this study focused on understanding the mechanisms underlying ocular hydrodynamics and the changes which occur in the eyes of subjects exposed to hypobaric hypoxia (HH) to permit the achievement of more detailed knowledge in glaucomatous disease. Twenty male subjects, aged 32±5 years, attending the Italian Air Force, were enrolled for this study. The research derived from hypobaric chamber, using helmet and mask supplied to jet pilotes connected to oxygen cylinder and equipped with a preset automatic mixer. The baseline values of intraocular pressure (IOP), recorded at T1, showed a mean of 16±2.23 mmHg, while climbing up to 18,000 feet the mean value was 13.7±4.17 mmHg, recorded at T2. The last assessment was performed returning to sea level (T4) where the mean IOP value was 12.8±2.57 mmHg, with a significant change (P<0.05) compared to T1. Pachymetry values related to corneal thickness in conditions of hypobarism revealed a statistically significant increase (P<0.05). The data collected in this research seem to confirm the increasing outflow of aqueous humor (AH) in the trabecular meshwork (TM) under conditions of HH.

Hypobaric Hypoxia: Effects on Intraocular Pressure and Corneal Thickness

PubMed Central

Di Blasio, Dario; Pescosolido, Nicola

2014-01-01

Objective. The purpose of this study focused on understanding the mechanisms underlying ocular hydrodynamics and the changes which occur in the eyes of subjects exposed to hypobaric hypoxia (HH) to permit the achievement of more detailed knowledge in glaucomatous disease. Methods. Twenty male subjects, aged 32 ± 5 years, attending the Italian Air Force, were enrolled for this study. The research derived from hypobaric chamber, using helmet and mask supplied to jet pilotes connected to oxygen cylinder and equipped with a preset automatic mixer. Results. The baseline values of intraocular pressure (IOP), recorded at T1, showed a mean of 16 ± 2.23 mmHg, while climbing up to 18,000 feet the mean value was 13.7 ± 4.17 mmHg, recorded at T2. The last assessment was performed returning to sea level (T4) where the mean IOP value was 12.8 ± 2.57 mmHg, with a significant change (P < 0.05) compared to T1. Pachymetry values related to corneal thickness in conditions of hypobarism revealed a statistically significant increase (P < 0.05). Conclusions. The data collected in this research seem to confirm the increasing outflow of aqueous humor (AH) in the trabecular meshwork (TM) under conditions of HH. PMID:24550712

Commercial air travel after intraocular gas injection.

PubMed

Houston, Stephen; Graf, Jürgen; Sharkey, James

2012-08-01

Passengers with intraocular gas are at risk of profound visual loss when exposed to reduced absolute pressure within the cabin of a typical commercial airliner. Information provided on the websites of the world's 10 largest airlines offer a considerable range of opinion as to when it might be safe to fly after gas injection. Physicians responsible for clearing pseassengers as 'fit to fly' should be aware modern retinal surgical techniques increasingly employ long-acting gases as vitreous substitutes. The kinetics of long-acting intraocular gases must be considered when deciding how long after surgery it is safe to travel. It is standard practice to advise passengers not to fly in aircraft until the gas is fully resorbed. To achieve this, it may be necessary to delay travel for approximately 2 wk after intraocular injection of sulfur hexafluoride (SF6) and for 6 wk after injection of perfluoropropane (C3F8).

Temporal evolution of intraocular pressure elevation after pupillary dilation in pigment dispersion syndrome.

PubMed

Jewelewicz, Daniel A; Radcliffe, Nathan M; Liebmann, Jeffrey; Ritch, Robert

2009-03-01

To report 4 patients with pigment dispersion syndrome (PDS) who had delayed intraocular pressure (IOP) spikes after pharmacologic pupillary dilation. Four patients with a diagnosis of PDS with documented IOP spike after pharmacologic pupillary dilation were included. Study patients were examined before and after pupillary dilation. The amount of pigment present in the anterior chamber and the IOP were measured at hourly intervals. Although maximal pigment liberation occurred immediately after maximal dilation, the IOP continued to elevate for at least 1.5 hours. The increase in IOP after pupillary dilation may not occur simultaneously with maximal pigment liberation but may follow it after the pigment has settled out of the anterior chamber. This has implications for monitoring patients with PDS after dilation to detect and treat rises in IOP.

The effect of lateral decubitus position on nocturnal intraocular pressure over a habitual 24-hour period in healthy adults.

PubMed

Hao, Jie; Zhen, Yi; Wang, Hao; Yang, Diya; Wang, Ningli

2014-01-01

To investigate the effect of lateral decubitus position (LDP) on nocturnal intraocular pressure (IOP) and the effect of LDP on 24-hour habitual IOP pattern in healthy subjects. Intraocular pressure was measured every 2-hours using an Accupen Applanation Tonometer (Accutome, USA). During the diurnal period (7:30 am, 9:30 am, 11:30 am, 1:30 pm, 3:30 pm, 5:30 pm, 7:30 pm, and 9:30 pm), IOP was measured in the sitting position under bright light (500-1000 lux) after the subjects had been seated for 5 min. The nocturnal IOP was measured in the supine position, right LDP, and left LDP, with randomized sequences, under dim light (<10 lux) at 11:30 pm, 1:30 am, 3:30 am, and 5:30 am. The subjects were awakened and maintained each position for 5 min before the measurement. The 24-hour habitual IOP patterns were obtained according to the nocturnal position (supine, right LDP and left LDP) for either eye. P<0.05 was considered to be significant. Nineteen healthy subjects were included with a mean age of 51.3±5.8 years. During the nocturnal period, a significant IOP difference was found between the dependent eye (the eye on the lower side) of LDP and the supine position, but not for all the nocturnal time points. Over a 24-hour period, the effect of LDP on habitual IOP pattern was not statistically significant, although the mean nocturnal IOP and the diurnal-nocturnal IOP change for the right and the left eye in the LDP pattern was slightly higher than that in the sitting-supine pattern. Significant nocturnal IOP differences existed between the dependent eye and the supine, but did not occur consistently for all time points. Over a 24-hour period, the effect of LDP on habitual IOP pattern was not statistically significant in healthy subjects.

Change in intraocular pressure during scleral depression.

PubMed

Trevino, Richard; Stewart, Brandi

2015-01-01

Manometric studies have found that intraocular pressure (IOP) rises 116-350 mmHg during scleral depression in surgical settings. No information is available regarding the effect of scleral depression on IOP in routine clinical settings. The aim of this study is to quantify the change in IOP that occurs when scleral depression is performed on normal eyes in a routine clinical setting. A total of 28 eyes from 28 normal subjects were included. Tono-Pen tonometry was performed while scleral depression was performed in each of the two quadrants: superotemporal (ST) and inferonasal (IN). A post-procedure IOP measurement was obtained following each scleral depression examination. Both ST and IN quadrants were tested on all eyes, with the quadrant tested first chosen at random (15 ST, 13 IN). The mean IOP during scleral depression was 65.3 mmHg ST and 47.8 mmHg IN, with a maximum recorded IOP of 88 mmHg. The mean change in IOP for the ST quadrant was 51.9 ± 17.3 mmHg and 46.4 ± 16.0 mmHg for the right and left eyes, respectively. The mean change in IOP for the IN quadrant was 45.3 ± 22.7 mmHg and 16.8 ± 15.8 mmHg for the right and left eyes, respectively. Scleral depression as performed in a routine office setting produces wide fluctuations in IOP and may impair ocular perfusion. Additional studies are needed to determine the long-term consequences of routine scleral depression. Copyright © 2014 Spanish General Council of Optometry. Published by Elsevier Espana. All rights reserved.

Intraocular pressure changes: the influence of psychological stress and the Valsalva maneuver.

PubMed

Brody, S; Erb, C; Veit, R; Rau, H

1999-10-01

The effects of psychological stress and the Valsalva maneuver on short-term variations of intraocular pressure (IOP) were studied in 49 healthy adults. Psychological stress consisted of mental arithmetic tasks presented in counterbalanced order by computer and by the experimenter. Additionally, a standardized Valsalva maneuver was performed (in counterbalanced order with the psychological stressors). IOP was measured with a Goldmann tonometer before and after performance of each stressor. All three stressors transiently and highly significantly increased IOP, although the Valsalva maneuver produced changes of a greater magnitude (10.2 mmHg) than the psychological stressors (1.3 mmHg). Subjective stress ratings and heart rate increased in response to all stressors. There were no effects of task sequence, eye muscle tension, sex, smoking status (some smokers misreported their smoking status), or regular marijuana use, but regular physical exercise was associated with less IOP increase during psychological stress.

Noise Reduction of Ocean-Bottom Pressure Data Toward Real-Time Tsunami Forecasting

NASA Astrophysics Data System (ADS)

Tsushima, H.; Hino, R.

2008-12-01

We discuss a method of noise reduction of ocean-bottom pressure data to be fed into the near-field tsunami forecasting scheme proposed by Tsushima et al. [2008a]. In their scheme, the pressure data is processed in real time as follows: (1) removing ocean tide components by subtracting the sea-level variation computed from a theoretical tide model, (2) applying low-pass digital filter to remove high-frequency fluctuation due to seismic waves, and (3) removing DC-offset and linear-trend component to determine a baseline of relative sea level. However, it turns out this simple method is not always successful in extracting tsunami waveforms from the data, when the observed amplitude is ~1cm. For disaster mitigation, accurate forecasting of small tsunamis is important as well as large tsunamis. Since small tsunami events occur frequently, successful tsunami forecasting of those events are critical to obtain public reliance upon tsunami warnings. As a test case, we applied the data-processing described above to the bottom pressure records containing tsunami with amplitude less than 1 cm which was generated by the 2003 Off-Fukushima earthquake occurring in the Japan Trench subduction zone. The observed pressure variation due to the ocean tide is well explained by the calculated tide signals from NAO99Jb model [Matsumoto et al., 2000]. However, the tide components estimated by BAYTAP-G [Tamura et al., 1991] from the pressure data is more appropriate for predicting and removing the ocean tide signals. In the pressure data after removing the tide variations, there remain pressure fluctuations with frequencies ranging from about 0.1 to 1 mHz and with amplitudes around ~10 cm. These fluctuations distort the estimation of zero-level and linear trend to define relative sea-level variation, which is treated as tsunami waveform in the subsequent analysis. Since the linear trend is estimated from the data prior to the origin time of the earthquake, an artificial linear trend is

Design and evaluation of an intraocular B-scan OCT-guided 36-gauge needle

NASA Astrophysics Data System (ADS)

Shen, Jin H.; Joos, Karen M.

2015-03-01

Optical coherence tomography imaging is widely used in ophthalmology and optometry clinics for diagnosing retinal disorders. External microscope-mounted OCT operating room systems have imaged retinal changes immediately following surgical manipulations. However, the goal is to image critical surgical maneuvers in real time. External microscope-mounted OCT systems have some limitations with problems tracking constantly moving intraocular surgical instruments, and formation of absolute shadows by the metallic surgical instruments upon the underlying tissues of interest. An intraocular OCT-imaging probe was developed to resolve these problems. A disposable 25-gauge probe tip extended beyond the handpiece, with a 36-gauge needle welded to a disposable tip with its end extending an additional 3.5 mm. A sealed 0.35 mm diameter GRIN lens protected the fiber scanner and focused the scanning beam at a 3 to 4 mm distance. The OCT engine was a very high-resolution spectral-domain optical coherence tomography (SDOCT) system (870 nm, Bioptigen, Inc. Durham, NC) which produced 2000 A-scan lines per B-scan image at a frequency of 5 Hz with the fiber optic oscillations matched to this frequency. Real-time imaging of the needle tip as it touched infrared paper was performed. The B-scan OCT-needle was capable of real-time performance and imaging of the phantom material. In the future, the B-scan OCT-guided needle will be used to perform sub-retinal injections.

System for Rapid, Precise Modulation of Intraocular Pressure, toward Minimally-Invasive In Vivo Measurement of Intracranial Pressure

PubMed Central

Stockslager, Max A.; Samuels, Brian C.; Allingham, R. Rand; Klesmith, Zoe A.; Schwaner, Stephen A.; Forest, Craig R.; Ethier, C. Ross

2016-01-01

Pathologic changes in intracranial pressure (ICP) are commonly observed in a variety of medical conditions, including traumatic brain injury, stroke, brain tumors, and glaucoma. However, current ICP measurement techniques are invasive, requiring a lumbar puncture or surgical insertion of a cannula into the cerebrospinal fluid (CSF)-filled ventricles of the brain. A potential alternative approach to ICP measurement leverages the unique anatomy of the central retinal vein, which is exposed to both intraocular pressure (IOP) and ICP as it travels inside the eye and through the optic nerve; manipulating IOP while observing changes in the natural pulsations of the central retinal vein could potentially provide an accurate, indirect measure of ICP. As a step toward implementing this technique, we describe the design, fabrication, and characterization of a system that is capable of manipulating IOP in vivo with <0.1 mmHg resolution and settling times less than 2 seconds. In vitro tests were carried out to characterize system performance. Then, as a proof of concept, we used the system to manipulate IOP in tree shrews (Tupaia belangeri) while video of the retinal vessels was recorded and the caliber of a selected vein was quantified. Modulating IOP using our system elicited a rapid change in the appearance of the retinal vein of interest: IOP was lowered from 10 to 3 mmHg, and retinal vein caliber sharply increased as IOP decreased from 7 to 5 mmHg. Another important feature of this technology is its capability to measure ocular compliance and outflow facility in vivo, as demonstrated in tree shrews. Collectively, these proof-of-concept demonstrations support the utility of this system to manipulate IOP for a variety of useful applications in ocular biomechanics, and provide a framework for further study of the mechanisms of retinal venous pulsation. PMID:26771837

Real-Time Systems

DTIC Science & Technology

1992-02-01

Postgraduate School Autonomous Under Vehicle (AUV) are then examined. Autonomous underwater vehicle (AUV), hard real-time system, real - time operating system , real-time programming language, real-time system, soft real-time system.

Investigational and experimental drugs for intraocular pressure reduction in ocular hypertension and glaucoma.

PubMed

Lusthaus, Jed Asher; Goldberg, Ivan

2016-10-01

Intraocular pressure (IOP) is the most significant modifiable risk factor to prevent onset or progression of glaucoma. Glaucoma prevalence continues to increase, emphasizing the need for improved ocular hypotensive treatment options. To try to improve on both tolerance and IOP control of currently available therapies, different receptors or mechanisms are being explored to reduce IOP more effectively and to improve tolerance. We review synthetic topical and oral drugs in early development for the management of ocular hypertension and glaucoma. New therapeutic agents for IOP control have been discovered; some appear to be reasonably tolerated. IOP reduction may be limited with some agents, but other benefits although unproven may compensate for this, such as less ocular surface disease, enhanced neuro-protection or increased ocular blood flow. Further product development promises improved treatment options for ocular hypertensives and glaucoma sufferers.

Intraocular pressure decrease with preservative-free fixed and unfixed combination of tafluprost and timolol in pseudoexfoliative glaucoma.

PubMed

Holló, Gábor; Ropo, Auli

2015-01-01

We investigated the intraocular pressure (IOP) lowering efficacy of preservative-free fixed and non-fixed combination of tafluprost 0.0015% and timolol 0.5% in pseudoexfoliative glaucoma (XFG). A per protocol worse eye analysis was made on all XFG patients who participated in a recent 6 month, prospective, randomized, double-masked, parallel group, multicenter phase III study. The mean time-wise IOP decreased by 8.62 to 10.25 mmHg (31.8 to 36.7%) in the fixed dose combination arm (15 patients) and by 5.38 to 11.35 mmHg (21.3 to 41.2%) in the non-fixed combination arm (13 patients), respectively (p < 0.001 for all comparisons). The results show that a preservative-free fixed dose combination of tafluprost and timolol provides a clinically significant IOP reduction in XFG, and may offer an advantage for the XFG patients with dry eye, due to its preservative-free nature.

A new design and application of bioelastomers for better control of intraocular pressure in a glaucoma drainage device.

PubMed

Luong, Quang Minh; Shang, Lei; Ang, Marcus; Kong, Jen Fong; Peng, Yan; Wong, Tina T; Venkatraman, Subbu S

2014-02-01

Glaucoma drainage device (GDD) implantation is an effective method of lowering the intraocular pressure (IOP). Commonly used GDDs can be classified into nonvalved and valved. Although a stable IOP is critical, currently available devices often cause extreme IOP fluctuations: nonvalved GDDs suffer from a risk of hypotony (IOP<5 mmHg), whereas valved GDDs have a higher risk ocular hypertensive (IOP>22 mmHg). It is hypothesized that a GDD with a valve designed to open around the time of onset of the hypertensive phase, would minimize IOP fluctuation. Accordingly, a valve fabricated from a biodegradable polymer poly(L-lactide-co-ϵ-caprolactone) (PLC 70/30) is evaluated in vitro and in vivo. The pressure response is compared with its non-degradable counterpart in in vitro studies of IOP. It is also established that in vitro, the biodegradability of the valve is programmed to occur over 12 weeks. In vivo, a steady and low IOP is achieved with the biodegradable valve and the hypertensive phase is significantly attenuated compared with the commercial device. Fibrotic encapsulation of the device is also minimized with the biodegradable valve in vivo. Copyright © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Mechanisms for vasopressin effects on intraocular pressure in anesthetized rats

NASA Technical Reports Server (NTRS)

Balaban, C. D.; Palm, D. E.; Shikher, V.; Searles, R. V.; Keil, L. C.; Severs, W. B.

1997-01-01

Continuous intracameral infusions of a balanced salt solution (0.175 microliter min-1) have been reported to raise intraocular pressure (IOP) in anesthetized rats. Palm et al. (1995) previously reported that this effect was attenuated significantly by inclusion of arginine-vasopressin (AVP, 10 ng 0.175 microliter-1) in the infusate. This study used experimental and computer simulation methods to investigate factors underlying these changes in IOP. First, constant intracameral infusions of artificial cerebrospinal fluid (aCSF) at different fixed rates (0.049-0.35 microliter min-1) were used to estimate the outflow resistance. Secondly, IOP responses were measured during an 2 hr intracameral infusion of either aCSF or AVP that was the sum of a small constant component (0.05 microliter min-1) and a larger periodic component (0.25 microliter min-1, cycling for 4 min on, then 4 min off); the mean infusion rate was 0.175 microliter min-1. As shown previously for 0.175 microliter min-1 constant infusions, the periodic aCSF infusion induced a significant rise in IOP that was attenuated by AVP administration. Complex demodulation analysis and the estimated gain parameter of a second order transfer function fit to the periodic responses indicated that outflow resistance increased significantly during the infusions in both aCSF and AVP groups, but that the indices of resistance did not differ significantly between aCSF and AVP infused eyes. This finding implies that changes in outflow resistance do not explain the difference in IOP responses to intracameral aCSF and AVP. The two responses differed significantly, though, in damping factors, such that the aCSF responses were considerably more underdamped than the AVP responses. It is hypothesized that aCSF-induced increase in IOP reflects both (1) a small component reflecting increased outflow resistance and (2) a larger non-resistive component. Since the non-resistive component is insensitive to pretreatment with acetazolamide

Effects of morphine-alfaxalone-midazolam premedication, alfaxalone induction and sevoflurane maintenance on intraocular pressure and tear production in dogs.

PubMed

Mayordomo-Febrer, A; Rubio, M; Martínez-Gassent, M; López-Murcia, M M

2017-05-13

Intraocular pressure (IOP) and tear production are commonly affected by general anaesthesia. It is necessary to have a good control of both to guarantee successful ophthalmic surgery. The purpose of this research was to evaluate if the protocol based on the administration of morphine-alfaxalone-midazolam as premedication, alfaxalone as induction and sevoflurane as maintenance, can induce changes on IOP and Schirmer's tear test (STT-1) in healthy dogs. Twenty-two adult mixed-breed dogs scheduled for an ovariohysterectomy were enrolled for the study. IOP and STT-1 were registered at baseline (T 0 ), 5 minutes (T 1 ), 10 minutes (T 2 ) and 15 minutes (T 3 ) after premedication with a morphine-alfaxalone-midazolam combination; 5 minutes (T 4 ) after induction with alfaxalone and 15 minutes (T 5 ) and 25 minutes (T 6 ) after maintenance with sevoflurane. A one-way analysis of variance was performed to analyse the difference between IOP and STT-1 over time, respectively. The present study shows a slightly statistically significant increase in IOP (P<0.05) after premedication, induction and maintenance that can be associated with this anaesthetic protocol. STT-1 showed a statistically significant reduction during all the procedures (P<0.001). These results should be taken into consideration, especially in dogs with damaged corneas, in those predisposed to glaucoma and in those due to undergo intraocular surgery. Ocular lubrication is necessary if this protocol is used. British Veterinary Association.

Effect of sedation with detomidine on intraocular pressure with and without topical anesthesia in clinically normal horses.

PubMed

Holve, Dana L

2012-02-01

To determine the effect of sedation with detomidine on intraocular pressure (IOP) in standing horses and whether topical ocular application of anesthetic alters this effect. Clinical trial. 15 clinically normal horses. Horses were assigned to group 1 (n = 7) or 2 (8). Intraocular pressure measurements were obtained at baseline (before sedation) and 10 minutes after IV administration of detomidine (0.02 mg/kg [0.009 mg/lb]). Group 1 horses had an additional IOP measurement at 20 minutes after sedation. For group 2 horses, topical ocular anesthetic was administered 10 minutes prior to baseline IOP measurements. Mean ± SD baseline IOP for horses without topical anesthesia (group 1 horses; IOP, 24.30 ± 3.09 mm Hg) was significantly lower, compared with that of horses with topical anesthesia (group 2 horses; IOP, 30.40 ± 3.25 mm Hg). Compared with baseline values, IOP at 10 minutes after sedation decreased significantly in all horses (by 3.61 ± 1.48 mm Hg and 5.78 ± 4.32 mm Hg in groups 1 and 2, respectively). In group 1 horses, IOP at 10 (20.69 ± 3.45 mm Hg) and 20 (19.96 ± 2.13 mm Hg) minutes after sedation was significantly decreased, compared with baseline values; however, the difference between IOP at 10 versus 20 minutes was not significant. The difference in IOP between group 1 and 2 horses at 10 minutes after sedation was not significant. IV administration of detomidine caused a decrease in IOP in clinically normal horses and may be a safe sedative when performing ocular procedures.

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.

Distribution of intraocular pressure and its determinants in an Iranian adult population.

PubMed

Hashemi, Hassan; Khabazkhoob, Mehdi; Emamian, Mohammad Hassan; Shariati, Mohammad; Yekta, Abbasali; Fotouhi, Akbar

2016-01-01

To determine the distribution of intraocular pressure (IOP) and its determinants in an Iranian population. In a cross-sectional survey, random cluster sampling was conducted from the 40-64 years old population of Shahroud, in the north of Iran. All participants had optometry and ophthalmic exams. IOP was determined using the Goldmann tonometry method and biometric components were measured. Of the 6311 people selected for the study, 5190 (82.2%) participated. The mean age of the participants was 50.9±6.2y and 58.7% of them were female. Mean IOP was 12.87±2.27 mm Hg. In this study 0.3% of the participants had an IOP higher than 21 mm Hg. The multiple linear regression model revealed that sex (Coef=-0.30; 95% CI: -0.43 to -0.17), diabetes (Coef=0.43; 95% CI: 0.19 to 0.67), high systolic blood pressure (Coef=0.02; 95% CI: 0.01 to 0.02), high body mass index (BMI) (Coef=0.03; 95% CI: 0.01 to 0.04), higher education (Coef=0.02, 95% CI: 0.01 to 0.04), thicker central corneal thickness (Coef=0.01; 95% CI: 0.01 to 0.02), and myopic shift in spherical equivalent (Coef=-0.14; 95% CI: -0.18 to -0.10) significantly correlated with high IOP. The IOP in this 40-64 years old population is low overall. In the north of Iran, average IOP is statistically significantly correlated with female sex, diabetes, higher BMI, systolic blood pressure, higher education, thicker cornea, and myopic refractive error.

Real-time radiography support for Titan LAM

NASA Astrophysics Data System (ADS)

Anderson, M. G.

1992-07-01

This paper discusses real-time radiography (RTR) support for the Titan Lightweight Analog Motor (LAM) cold gas tests. RTR was used as a diagnostic technique to measure propellant deformation within the motors as gaseous nitrogen, at various pressures, was flowed over the propellant grain. The data consisted of video images that correlated the propellant deformation to time and to chamber pressure. Measurements were made on three propellant configurations in 17 tests. Specific issues addressed include the approach taken to gather the data, the system layout, and image processing techniques used to interpret the data.

Occurrence of intraocular air bubbles during intravitreal injections for retinopathy of prematurity.

PubMed

Sukgen, Emine Alyamac; Gunay, Murat; Kocluk, Yusuf

2017-02-01

This study aims to present five cases with retinopathy of prematurity (ROP) who were found to have intraocular air bubbles after intravitreal injection (IVI) treatment. The medical records of 148 infants who underwent IVI for ROP were retrospectively reviewed and the ones who demonstrated post-injection intraocular air bubble formation were recruited. Of the 148 patients (31 babies received ranibizumab, 20 babies received aflibercept, 97 babies received bevacizumab), five were found to have intraocular air bubbles right after the IVI. Two infants received intravitreal ranibizumab and three received intravitreal bevacizumab injections. Although intraocular pressure increased temporarily, no intraocular sterile or infective reactions were observed in the postoperative period. The air bubble was found to resorb spontaneously within 72 h. The occurrence rate of the intravitreal air bubbles in our series was 3.37 % despite previously not been reported in the literature. Due to the intravitreal air injection risk, it is important to be more careful while preparing the intravitreal medication before treatment in premature babies.

Real-time measurement of blood pressure with Nexfin in a patient with thalidomide-related phocomelia.

PubMed

Earle, Rosie; Vaghadia, Himat; Shanahan, Enda; Tang, Raymond; Sawka, Andrew

2016-11-01

We report the novel application of photoplethysmographic technology with the Nexfin HD monitor for real-time measurement of blood pressure (BP) in a patient with tetraamelia. The patient was a 58-year-old man with tetraamelia secondary to thalidomide exposure in utero, who presented for surgical excision of a maxillary schwannoma. Because difficulty of cuff use on rudimentary limbs and failure to gain invasive arterial access due to abnormalities of limb vasculature, this population is known to pose some unique challenges for BP measurement. Nexfin may offer an alternative noninvasive method to detect BP in patients with phocomelia during the perioperative period. Copyright © 2016 Elsevier Inc. All rights reserved.

Effects of topical travoprost 0.004% on intraocular pressure and corneal biomechanical properties in an animal model.

PubMed

Lazcano-Gomez, Gabriel; Ancona-Lezama, David; Gil-Carrasco, Felix; Jimenez-Roman, Jesus

2016-01-01

To determine whether topical application of travoprost 0.004% induces changes in corneal biomechanical properties affecting intraocular pressure (IOP) values in rabbits. Both eyes of 10 New Zealand rabbits were measured 3 times with the Ocular Response Analyzer (ORA) before treatment. Each measurement included corneal hysteresis (CH), corneal resistance factor (CRF), corneal-corrected IOP (IOPcc), and Goldmann equivalent IOP (IOPg). A drop of travoprost 0.004% was applied once daily in right eyes for 3 months; left eyes received no treatments. After 3 months of treatment both eyes of all rabbits were again measured 3 times. After complete keratectomy of both eyes, tissues prepared with hematoxylin-eosin stain were analyzed by means of light microscopy. The mean pre- and post-treatment IOPg, respectively, for right eyes was 9.92 ± 5.64 mm Hg and 7.62 ± 2.99 mm Hg (P = 0.027); IOPcc, 19.81 ± 5.25 mm Hg and 17.79 ± 4.09 mm Hg (P = 0.063); CRF, 1.65 ± 1.63 mm Hg and 2.18 ± 2.50 mm Hg (P = 0.266); and CH, 2.79 ± 1.74 mm Hg and 2.64 ± 2.08 mm Hg (P = 0.72). Mean post-treatment right and left eye IOPg values were, respectively, 7.62 ± 2.99 and 10.30 ± 4.40 (P = 0.002); IOPcc, 17.79 ± 4.09 mm Hg and 20.37 ± 4.32 mm Hg (P = 0.009); CRF, 1.65 ± 1.63 mm Hg and 2.17 ± 2.47 mm Hg (P = 0.274); and CH, 2.79 ± 1.74 mm Hg and 2.54 ± 2.08 mm Hg (P = 0.575). No difference in CH and CRF was observed between treated and untreated eyes. Post-treatment reduction of IOP in treated eyes was a direct hypotensive effect of travoprost 0.004% and was not affected by changes in corneal biomechanical properties (CH and CRF), resulting in real lower IOP values.

Effects of topical travoprost 0.004% on intraocular pressure and corneal biomechanical properties in an animal model

PubMed Central

Lazcano-Gomez, Gabriel; Ancona-Lezama, David; Gil-Carrasco, Felix; Jimenez-Roman, Jesus

2016-01-01

Purpose To determine whether topical application of travoprost 0.004% induces changes in corneal biomechanical properties affecting intraocular pressure (IOP) values in rabbits. Methods Both eyes of 10 New Zealand rabbits were measured 3 times with the Ocular Response Analyzer (ORA) before treatment. Each measurement included corneal hysteresis (CH), corneal resistance factor (CRF), corneal-corrected IOP (IOPcc), and Goldmann equivalent IOP (IOPg). A drop of travoprost 0.004% was applied once daily in right eyes for 3 months; left eyes received no treatments. After 3 months of treatment both eyes of all rabbits were again measured 3 times. After complete keratectomy of both eyes, tissues prepared with hematoxylin-eosin stain were analyzed by means of light microscopy. Results The mean pre- and post-treatment IOPg, respectively, for right eyes was 9.92 ± 5.64 mm Hg and 7.62 ± 2.99 mm Hg (P = 0.027); IOPcc, 19.81 ± 5.25 mm Hg and 17.79 ± 4.09 mm Hg (P = 0.063); CRF, 1.65 ± 1.63 mm Hg and 2.18 ± 2.50 mm Hg (P = 0.266); and CH, 2.79 ± 1.74 mm Hg and 2.64 ± 2.08 mm Hg (P = 0.72). Mean post-treatment right and left eye IOPg values were, respectively, 7.62 ± 2.99 and 10.30 ± 4.40 (P = 0.002); IOPcc, 17.79 ± 4.09 mm Hg and 20.37 ± 4.32 mm Hg (P = 0.009); CRF, 1.65 ± 1.63 mm Hg and 2.17 ± 2.47 mm Hg (P = 0.274); and CH, 2.79 ± 1.74 mm Hg and 2.54 ± 2.08 mm Hg (P = 0.575). No difference in CH and CRF was observed between treated and untreated eyes. Conclusions Post-treatment reduction of IOP in treated eyes was a direct hypotensive effect of travoprost 0.004% and was not affected by changes in corneal biomechanical properties (CH and CRF), resulting in real lower IOP values. PMID:27330476

Cannabinoids in glaucoma II: the effect of different cannabinoids on intraocular pressure of the rabbit.

PubMed

ElSohly, M A; Harland, E C; Benigni, D A; Waller, C W

1984-06-01

Thirty-two different cannabinoids were tested for their ability to reduce intraocular pressure (IOP) in the rabbit. These included many of delta 9- and delta 8-THC derivatives and metabolites along with other natural and synthetic cannabinoids. In addition, some non-cannabinoid constituents of Cannabis were screened using the same model. All compounds were administered intravenously, while only a few were tested topically in mineral oil. Water soluble derivatives of delta 9- and delta 8-THC were prepared and tested topically in aqueous solution. The data revealed that certain derivatives of delta 9-and delta 8-THC were more active in lowering IOP than the parent cannabinoids. In addition, compounds other than delta 9- and delta 8-THC and their derivatives were shown to have activity.

In-vivo effects of intraocular and intracranial pressures on the lamina cribrosa microstructure

PubMed Central

Smith, Matthew A.; Kostanyan, Tigran; Schmitt, Samantha E.; Bilonick, Richard A.; Jan, Ning-Jiun; Kagemann, Larry; Tyler-Kabara, Elizabeth C.; Ishikawa, Hiroshi; Schuman, Joel S.; Wollstein, Gadi

2017-01-01

There is increasing clinical evidence that the eye is not only affected by intraocular pressure (IOP), but also by intracranial pressure (ICP). Both pressures meet at the optic nerve head of the eye, specifically the lamina cribrosa (LC). The LC is a collagenous meshwork through which all retinal ganglion cell axons pass on their way to the brain. Distortion of the LC causes a biological cascade leading to neuropathy and impaired vision in situations such as glaucoma and idiopathic intracranial hypertension. While the effect of IOP on the LC has been studied extensively, the coupled effects of IOP and ICP on the LC remain poorly understood. We investigated in-vivo the effects of IOP and ICP, controlled via cannulation of the eye and lateral ventricle in the brain, on the LC microstructure of anesthetized rhesus monkeys eyes using the Bioptigen spectral-domain optical coherence tomography (OCT) device (Research Triangle, NC). The animals were imaged with their head upright and the rest of their body lying prone on a surgical table. The LC was imaged at a variety of IOP/ICP combinations, and microstructural parameters, such as the thickness of the LC collagenous beams and diameter of the pores were analyzed. LC microstructure was confirmed by histology. We determined that LC microstructure deformed in response to both IOP and ICP changes, with significant interaction between the two. These findings emphasize the importance of considering both IOP and ICP when assessing optic nerve health. PMID:29161320

Manual suction versus femtosecond laser trephination for penetrating keratoplasty: intraocular pressure, endothelial cell damage, incision geometry, and wound healing responses.

PubMed

Angunawela, Romesh I; Riau, Andri; Chaurasia, Shyam S; Tan, Donald T; Mehta, Jodhbir S

2012-05-04

To measure real-time intraocular pressure (IOP) during trephination with a manual suction trephine (MST) and the femtosecond laser (FSL), and to assess endothelial cell damage, incision geometry, and wound healing response with these procedures. IOP was monitored with an intracameral sensor. Eight rabbits underwent manual suction trephination. Eight rabbits had FSL trephination (FSL-T). Slit lamp photography, confocal microscopy, and anterior segment optical coherence tomography (AS-OCT) were performed at baseline and postoperatively. Animals were sacrificed at 4 hours and 3 days. Tissue was examined with scanning electron microscopy (SEM) and immunohistochemistry for an array of wound-healing markers. Separately, 6 human corneas had MST (3) and FSL-T (3). Incision geometry was imaged with high resolution Optovue AS-OCT. The average IOP during MST and FSL-T was similar (37 mm Hg). There was wider IOP fluctuation during the MST cutting phase (60 mm Hg maximum). There were 1-2 rows of endothelial loss on either side of the incision for FSL-T and 2-5 rows deep for MST. Immune cell responses at 4 hours (CD11b) were comparable, greater apoptosis with FSL-T (TUNEL) occurred at 4 hours, and there was increased keratocyte proliferation at 3 days (Ki67) with FSL-T. There was significantly greater undercutting of the cornea with MST (46.86 degrees versus 16.72 degrees). There is more IOP variation during MST. Average IOP is 37 mm Hg for both techniques. More endothelial damage and undercutting of the cornea occurs with MST. The wound healing response to FSL-T appears greater at 3 days.

Outflow resistance of the Baerveldt glaucoma drainage implant and modifications for early postoperative intraocular pressure control.

PubMed

Breckenridge, R Reid; Bartholomew, Luanna R; Crosson, Craig E; Kent, Alexander R

2004-10-01

To determine outflow resistance of the Baerveldt glaucoma implant using different tube configurations. Outflow resistance of 6 tube configurations (C1- C6) of Baerveldt implants was measured under conditions of constant pressure perfusion. Pressures ranged from 2 to 55 mm Hg. Venting slits were created using a 7-0 Vicryl, spatulated suture-needle. Seton tubes were occluded by threading a retrograde suture approximately 1.5 cm into the lumen. At pressures between 2 and 55 mm Hg, mean outflow resistance of the normally configured seton (ie, open tube; C1) was 0.41 (+/- 0.6) mm Hg/microL/min. Resistance was unchanged (mean 0.41 (+/- 0.4) mm Hg/microL/min) by the addition of 4 venting slits (C2) to the seton tube. Occlusion of the open seton tube with a 3-0 Supramid suture (C3) significantly increased (P < 0.001) mean outflow resistance to 14.99 (+/- 0.6) mm Hg/microL/min. Occlusion of the tube with a 4-0 Supramid suture (C4) significantly increased (P < 0.001) mean outflow resistance to 1.09 (+/- 0.5) mm Hg/microL/min. In implants where tubes were occluded with a 3-0 Supramid suture, the addition of venting slits (C5) significantly decreased (P = 0.038) mean outflow resistance to 8.98 (+/- 0.4) mm Hg/microL/min. In tubes occluded with a 4-0 Supramid suture, the addition of venting slits (C6) decreased mean outflow resistance to 0.98 (+/- 0.6) mm Hg/microL/min. Although these results cannot be directly correlated to the clinical setting, they do show that outflow resistance can be modified at the time of surgery by changing tube configuration of the Baerveldt glaucoma implant. Configuration C5 (3-0 Supramid with venting slits) closely approximates the outflow rate in the normal intraocular pressure range.

Genetic correlations between intraocular pressure, blood pressure and primary open-angle glaucoma: a multi-cohort analysis.

PubMed

Aschard, Hugues; Kang, Jae H; Iglesias, Adriana I; Hysi, Pirro; Cooke Bailey, Jessica N; Khawaja, Anthony P; Allingham, R Rand; Ashley-Koch, Allison; Lee, Richard K; Moroi, Sayoko E; Brilliant, Murray H; Wollstein, Gadi; Schuman, Joel S; Fingert, John H; Budenz, Donald L; Realini, Tony; Gaasterland, Terry; Scott, William K; Singh, Kuldev; Sit, Arthur J; Igo, Robert P; Song, Yeunjoo E; Hark, Lisa; Ritch, Robert; Rhee, Douglas J; Gulati, Vikas; Haven, Shane; Vollrath, Douglas; Zack, Donald J; Medeiros, Felipe; Weinreb, Robert N; Cheng, Ching-Yu; Chasman, Daniel I; Christen, William G; Pericak-Vance, Margaret A; Liu, Yutao; Kraft, Peter; Richards, Julia E; Rosner, Bernard A; Hauser, Michael A; Klaver, Caroline C W; vanDuijn, Cornelia M; Haines, Jonathan; Wiggs, Janey L; Pasquale, Louis R

2017-11-01

Primary open-angle glaucoma (POAG) is the most common chronic optic neuropathy worldwide. Epidemiological studies show a robust positive relation between intraocular pressure (IOP) and POAG and modest positive association between IOP and blood pressure (BP), while the relation between BP and POAG is controversial. The International Glaucoma Genetics Consortium (n=27 558), the International Consortium on Blood Pressure (n=69 395), and the National Eye Institute Glaucoma Human Genetics Collaboration Heritable Overall Operational Database (n=37 333), represent genome-wide data sets for IOP, BP traits and POAG, respectively. We formed genome-wide significant variant panels for IOP and diastolic BP and found a strong relation with POAG (odds ratio and 95% confidence interval: 1.18 (1.14-1.21), P=1.8 × 10 -27 ) for the former trait but no association for the latter (P=0.93). Next, we used linkage disequilibrium (LD) score regression, to provide genome-wide estimates of correlation between traits without the need for additional phenotyping. We also compared our genome-wide estimate of heritability between IOP and BP to an estimate based solely on direct measures of these traits in the Erasmus Rucphen Family (ERF; n=2519) study using Sequential Oligogenic Linkage Analysis Routines (SOLAR). LD score regression revealed high genetic correlation between IOP and POAG (48.5%, P=2.1 × 10 -5 ); however, genetic correlation between IOP and diastolic BP (P=0.86) and between diastolic BP and POAG (P=0.42) were negligible. Using SOLAR in the ERF study, we confirmed the minimal heritability between IOP and diastolic BP (P=0.63). Overall, IOP shares genetic basis with POAG, whereas BP has limited shared genetic correlation with IOP or POAG.

Circadian rhythm of intraocular pressure in the rat.

PubMed

Moore, C G; Johnson, E C; Morrison, J C

1996-02-01

To define the characteristics of the diurnal variation of intraocular pressure (IOP) in eyes of awake rats, ten male brown Norway rats were entrained to a 12-hour light:12-hour dark (12L:12D) lighting schedule and were conditioned to IOP measurement with the TonoPen XL tonometer while awake, using only 0.5% proparacaine HCl anesthesia. The IOP measurements were performed in 4 experiments: Preliminary-IOP was measured at 6-hour intervals in both eyes of each animal, to determine correlation between right and left eyes; Light:Dark-lighting remained the same as in the preliminary experiment, but the measurement schedule was altered so that measurements were obtained at 4-hour intervals in alternating eyes, over two 24-hour light cycles; Dark:Dark-animals were placed in constant dark (0L:24D) and, after 72 h, measurements were obtained at 4-hour intervals in alternating eyes. Animals were then re-entrained to the previous 12L:12D schedule for 7 days, after which they were returned to constant dark and the experiment was repeated; and Dark:Light-animals were entrained to a reversed light:dark cycle (12D:12L) for 28 days, after which measurements were obtained in the same fashion as in the Light:Dark experiment. Close agreement was found between right- and left-eye IOPs. Animals on a 12L:12D schedule exhibited lowest IOP while the lights were on (19.3 +/- 1.9 mm Hg), and highest (31.3 +/- 1.3 mm Hg) while the lights were off. Pressure changes anticipated the change from light to dark and dark to light. This pattern persisted in constant dark, and was reversed when the cycle was changed to 12D:12L. Brown Norway rats possess a regular rhythm of IOP that is entrained by the cycle of light and dark, and persistence of this rhythm in constant dark establishes it as a circadian rhythm. Furthermore, our results indicate that reliable and physiologically meaningful IOP measurements can be obtained in awake rats using the TonoPen XL tonometer.

Tonopen XL assessment of intraocular pressure through silicone hydrogel contact lenses.

PubMed

Schornack, Muriel; Rice, Melissa; Hodge, David

2012-09-01

To assess the accuracy of Tonopen XL measurement of intraocular pressure (IOP) through low-power (-0.25 to -3.00) and high power (-3.25 to -6.00) silicone hydrogel lenses of 3 different materials (galyfilcon A, senofilcon A, and lotrafilcon B). Seventy-eight patients were recruited for participation in this study. All were habitual wearers of silicone hydrogel contact lenses, and none had been diagnosed with glaucoma, ocular hypertension, or anterior surface disease. IOP was measured with and without lenses in place in the right eye only. Patients were randomized to initial measurement either with or without the lens in place. A single examiner collected all data. No statistically significant differences were noted between IOP measured without lenses and IOP measured through low-power lotrafilcon B lenses or high-power or low-power galyfilcon A and senofilcon A lenses. However, we did find a statistically significant difference between IOP measured without lenses and IOP measured through high-power lotrafilcon B lenses. In general, Tonopen XL measurement of IOP through silicone hydrogel lenses may be sufficiently accurate for clinical purposes. However, Tonopen XL may overestimate IOP if performed through a silicone hydrogel lens of relatively high modulus.

Real-Time CORBA

DTIC Science & Technology

2000-10-01

control systems and prototyped the approach by porting the ILU ORB from Xerox to the Lynx real - time operating system . They then provided a distributed...compliant real - time operating system , a real-time ORB, and an ODMG-compliant real-time ODBMS [12]. The MITRE system is an infrastructure for...the server’s local operating system can handle. For instance, on a node controlled by the VXWorks real - time operating system with 256 local

Distribution of intraocular pressure and its determinants in an Iranian adult population

PubMed Central

Hashemi, Hassan; Khabazkhoob, Mehdi; Emamian, Mohammad Hassan; Shariati, Mohammad; Yekta, Abbasali; Fotouhi, Akbar

2016-01-01

AIM To determine the distribution of intraocular pressure (IOP) and its determinants in an Iranian population. METHODS In a cross-sectional survey, random cluster sampling was conducted from the 40-64 years old population of Shahroud, in the north of Iran. All participants had optometry and ophthalmic exams. IOP was determined using the Goldmann tonometry method and biometric components were measured. RESULTS Of the 6311 people selected for the study, 5190 (82.2%) participated. The mean age of the participants was 50.9±6.2y and 58.7% of them were female. Mean IOP was 12.87±2.27 mm Hg. In this study 0.3% of the participants had an IOP higher than 21 mm Hg. The multiple linear regression model revealed that sex (Coef=-0.30; 95% CI: -0.43 to -0.17), diabetes (Coef=0.43; 95% CI: 0.19 to 0.67), high systolic blood pressure (Coef=0.02; 95% CI: 0.01 to 0.02), high body mass index (BMI) (Coef=0.03; 95% CI: 0.01 to 0.04), higher education (Coef=0.02, 95% CI: 0.01 to 0.04), thicker central corneal thickness (Coef=0.01; 95% CI: 0.01 to 0.02), and myopic shift in spherical equivalent (Coef=-0.14; 95% CI: -0.18 to -0.10) significantly correlated with high IOP. CONCLUSION The IOP in this 40-64 years old population is low overall. In the north of Iran, average IOP is statistically significantly correlated with female sex, diabetes, higher BMI, systolic blood pressure, higher education, thicker cornea, and myopic refractive error. PMID:27588277

Upcoming Methods and Specifications of Continuous Intraocular Pressure Monitoring Systems for Glaucoma

PubMed Central

Molaei, Amir; Karamzadeh, Vahid; Safi, Sare; Esfandiari, Hamed; Dargahi, Javad; Khosravi, Mohammad Azam

2018-01-01

Glaucoma is the leading cause of irreversible blindness and vision loss in the world. Although intraocular pressure (IOP) is no longer considered the only risk factor for glaucoma, it is still the most important one. In most cases, high IOP is secondary to trabecular meshwork dysfunction. High IOP leads to compaction of the lamina cribrosa and subsequent damage to retinal ganglion cell axons. Damage to the optic nerve head is evident on funduscopy as posterior bowing of the lamina cribrosa and increased cupping. Currently, the only documented method to slow or halt the progression of this disease is to decrease the IOP; hence, accurate IOP measurement is crucial not only for diagnosis, but also for the management. Due to the dynamic nature and fluctuation of the IOP, a single clinical measurement is not a reliable indicator of diurnal IOP; it requires 24-hour monitoring methods. Technological advances in microelectromechanical systems and microfluidics provide a promising solution for the effective measurement of IOP. This paper provides a broad overview of the upcoming technologies to be used for continuous IOP monitoring. PMID:29403593

Twenty-four hour intraocular pressure monitoring with the SENSIMED Triggerfish contact lens: effect of body posture during sleep.

PubMed

Beltran-Agulló, Laura; Buys, Yvonne M; Jahan, Farzana; Shapiro, Colin M; Flanagan, John G; Cheng, Jason; Trope, Graham E

2017-10-01

To determine the difference in relative intraocular pressure (IOP) measured by the SENSIMED Triggerfish (TF) contact lens in flat compared with 30° head-up sleeping positions in patients with progressive primary open-angle glaucoma or normotensive glaucoma, based on recent or recurrent disc haemorrhage. Prospective, randomised, cross-over, open-label comparative study. IOP was monitored for 24 hours using TF on two separate sessions. Patients were randomly assigned to sleep flat one night and 30° head-up the other. Outputs in arbitrary units were obtained. Sleep and wake periods were defined as 22:00-6:00 and 8:00-22:00, respectively. Mean TF values during sleep and wake periods and wake-sleep and sleep-wake slopes were calculated for each session. TF output signals were compared between positions. Twelve subjects completed the study. Significant mean positive slopes were noted during the sleep period for both positions (p<0.01). No significant differences in the TF mean values were observed between positions (p=0.51). Six (54%) subjects had mean TF values significantly higher during the flat supine session, while four (36%) subjects had higher values during the head-up session. A significant increase in Goldmann IOP (p=0.001) and TF (p=0.02) measurements were observed after 24 hours of TF wear ('drift phenomenon'). Sleep position affects IOP as measured by TF in some patients with progressive glaucoma. The upward drift in TF output detected in >50% of the subjects requires further investigation to establish whether the increased output values over time are an artefact induced by the TF or a real change in IOP. NCT01351779. 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/.

Circadian rhythm of intraocular pressure in cats.

PubMed

Del Sole, María J; Sande, Pablo H; Bernades, José M; Aba, Marcelo A; Rosenstein, Ruth E

2007-01-01

To evaluate the rhythm of intraocular pressure (IOP) in healthy domestic cats with no evidence of ocular disease and to analyze the influence of photoperiod, age, gender and ocular diseases on diurnal-nocturnal variations of cat IOP. All animals were Domestic Short-haired cats; 30 were without systemic or ocular diseases, classified as follows: 12 male intact adult cats, five intact adult female, five adult spayed female, and eight male cats; the latter were less than 1 year of age. In addition, five adult cats with uveitis and three adult cats with secondary glaucoma were included. IOP was assessed with a Tono-Pen XL at 3-h intervals over a 24-h period in 12 healthy adult male cats kept under a photoperiod of 12-h light/12-h darkness for 2 weeks. Eight animals from the same group were then kept under constant darkness for 48 h, and IOP was measured at 3-h intervals for the following 24 h. In addition, IOP was assessed at 3 p.m. and 9 p.m. in five intact females, five spayed females, and in eight young cats, as well as in five adult cats with uveitis and three glaucomatous cats. Consistent, daily variations in IOP were observed in animals exposed to a light-dark cycle, with maximal values during the night. In cats exposed to constant darkness, maximal values of IOP were observed at subjective night. Differences of IOP values between 3 p.m. and 9 p.m. (diurnal-nocturnal variations) persisted in intact females, spayed females, and young animals, as well as in uveitic and glaucomatous eyes. The present results indicate a daily rhythm of cat IOP, which appears to persist in constant darkness, suggesting some level of endogenous circadian control. In addition, daily variations of cat IOP seem to be independent of gender, age, or ocular diseases (particularly uveitis and glaucoma).

Intraocular pressure and pulsatile ocular blood flow after retrobulbar and peribulbar anaesthesia

PubMed Central

Watkins, R.; Beigi, B.; Yates, M.; Chang, B.; Linardos, E.

2001-01-01

AIMS—This study investigated the effect of peribulbar and retrobulbar local anaesthesia on intraocular pressure (IOP) and pulsatile ocular blood flow (POBF), as such anaesthetic techniques may adversely affect these parameters.
METHODS—20 eyes of 20 patients who were to undergo phacoemulsification cataract surgery were prospectively randomised to receive peribulbar or retrobulbar anaesthesia. The OBF tonometer (OBF Labs, Wiltshire, UK) was used to simultaneously measure IOP and POBF before anaesthesia and 1 minute and 10 minutes after anaesthesia. Between group comparisons of age, baseline IOP, and baseline POBF were performed using the non-parametric Mann-Whitney test. Within group comparisons of IOP and POBF measured preanaesthesia and post-anaesthesia were performed using the non-parametric Wilcoxon signed ranks test for both groups.
RESULTS—There was no statistically significant IOP increase post-anaesthesia in either group. In the group receiving peribulbar anaesthesia, there was a significant reduction in POBF initially post-anaesthesia which recovered after 10 minutes. In the group receiving retrobulbar anaesthesia, there was a persistent statistically significant reduction in POBF.
CONCLUSIONS—Retrobulbar and peribulbar injections have little effect on IOP. Ocular compression is not needed for IOP reduction when using local anaesthesia for cataract surgery. Conversely, POBF falls, at least for a short time, when anaesthesia for ophthalmic surgery is administered via a retrobulbar route or a peribulbar route. This reduction may be mediated by pharmacologically altered orbital vascular tone. It may be safer to use other anaesthetic techniques in patients with ocular vascular compromise.

 PMID:11423451

Measurement of intraocular pressure in healthy unanesthetized inland bearded dragons (Pogona vitticeps).

PubMed

Schuster, Eva J; Strueve, Julia; Fehr, Michael J; Mathes, Karina A

2015-06-01

To evaluate the use of rebound and applanation tonometry for the measurement of intraocular pressure (IOP) and to assess diurnal variations in and the effect of topical anesthesia on the IOP of healthy inland bearded dragons (Pogona vitticeps). 56 bearded dragons from 4 months to 11 years old. For each animal following an initial ophthalmic examination, 3 IOP measurements were obtained on each eye between 9 AM and 10 AM, 1 PM and 2 PM, and 5 PM and 7 PM by use of rebound and applanation tonometry. An additional measurement was obtained by rebound tonometry for each eye in the evening following the application of a topical anesthetic to evaluate changes in the tolerance of the animals to the tonometer. Descriptive data were generated, and the effects of sex, time of day, and topical anesthesia on IOP were evaluated. Bearded dragons did not tolerate applanation tonometry even following topical anesthesia. Median daily IOP as determined by rebound tonometry was 6.16 mm Hg (95% confidence interval, 5.61 to 6.44 mm Hg). The IOP did not differ significantly between the right and left eyes. The IOP was highest in the morning, which indicated that the IOP in this species undergoes diurnal variations. Topical anesthesia did not significantly affect IOP, but it did improve the compliance for all subjects. Results indicated that rebound tonometry, but not applanation tonometry, was appropriate for measurement of IOP in bearded dragons. These findings provided preliminary guidelines for IOP measurement and ophthalmic evaluation in bearded dragons.

Effect of sublingual application of cannabinoids on intraocular pressure: a pilot study.

PubMed

Tomida, Ileana; Azuara-Blanco, Augusto; House, Heather; Flint, Maggie; Pertwee, Roger G; Robson, Philip J

2006-10-01

The purpose of this study was to assess the effect on intraocular pressure (IOP) and the safety and tolerability of oromucosal administration of a low dose of delta-9-tetrahydrocannabinol (Delta-9-THC) and cannabidiol (CBD). A randomized, double-masked, placebo-controlled, 4 way crossover study was conducted at a single center, using cannabis-based medicinal extract of Delta-9-THC and CBD. Six patients with ocular hypertension or early primary open angle glaucoma received a single sublingual dose at 8 AM of 5 mg Delta-9-THC, 20 mg CBD, 40 mg CBD, or placebo. Main outcome measure was IOP. Secondary outcomes included visual acuity, vital signs, and psychotropic effects. Two hours after sublingual administration of 5 mg Delta-9-THC, the IOP was significantly lower than after placebo (23.5 mm Hg vs. 27.3 mm Hg, P=0.026). The IOP returned to baseline level after the 4-hour IOP measurement. CBD administration did not reduce the IOP at any time. However, the higher dose of CBD (40 mg) produced a transient elevation of IOP at 4 hours after administration, from 23.2 to 25.9 mm Hg (P=0.028). Vital signs and visual acuity were not significantly changed. One patient experienced a transient and mild paniclike reaction after Delta-9-THC administration. A single 5 mg sublingual dose of Delta-9-THC reduced the IOP temporarily and was well tolerated by most patients. Sublingual administration of 20 mg CBD did not reduce IOP, whereas 40 mg CBD produced a transient increase IOP rise.

Real Time Revisited

NASA Astrophysics Data System (ADS)

Allen, Phillip G.

1985-12-01

The call for abolishing photo reconnaissance in favor of real time is once more being heard. Ten years ago the same cries were being heard with the introduction of the Charge Coupled Device (CCD). The real time system problems that existed then and stopped real time proliferation have not been solved. The lack of an organized program by either DoD or industry has hampered any efforts to solve the problems, and as such, very little has happened in real time in the last ten years. Real time is not a replacement for photo, just as photo is not a replacement for infra-red or radar. Operational real time sensors can be designed only after their role has been defined and improvements made to the weak links in the system. Plodding ahead on a real time reconnaissance suite without benefit of evaluation of utility will allow this same paper to be used ten years from now.

Patterns of intraocular pressure elevation after aqueous humor outflow obstruction in rats.

PubMed

Jia, L; Cepurna, W O; Johnson, E C; Morrison, J C

2000-05-01

To determine the diural intraocular pressure (IOP) response of Brown Norway rat eyes after sclerosis of the aqueous humor outflow pathways and its relationship to optic nerve damage. Hypertonic saline was injected into a single episcleral vein in 17 animals and awake IOP measured in both the light and dark phases of the circadian cycle for 34 days. Mean IOP for light and dark phases during the experimental period were compared with the respective pressures of the uninjected fellow eyes. Optic nerve cross sections from each nerve were graded for injury by five independent masked observers. For fellow eyes, mean light- and dark-phase IOP was 21 +/- 1 and 31 +/- 1 mm Hg, respectively. For four experimental eyes, mean IOPs for both phases were not altered. Six eyes demonstrated significant mean IOP elevations only during the dark phase. Of these, five showed persistent, large circadian oscillations, and four had partial optic nerve lesions. The remaining seven eyes experienced significant IOP elevations during both phases, and all had extensive optic nerve damage. Episcleral vein injection of hypertonic saline is more likely to increase IOP during the dark phase than the light. This is consistent with aqueous outflow obstruction superimposed on a circadian rhythm of aqueous humor production. Because these periodic IOP elevations produced optic nerve lesions, both light- and dark-phase IOP determinations are necessary for accurate correlation of IOP history to optic nerve damage in animals housed in a light- dark environment.

Evaluation of retinal ganglion cell function after intraocular pressure reduction measured by pattern electroretinogram in patients with primary open-angle glaucoma.

PubMed

Karaśkiewicz, Joanna; Penkala, Krzysztof; Mularczyk, Maciej; Lubiński, Wojciech

2017-04-01

To evaluate retinal ganglion cell (RGC) function after intraocular pressure (IOP) reduction measured by pattern electroretinogram (PERG) in patients with newly diagnosed, non-treated preperimetric and early stages of primary open-angle glaucoma (POAG). Twenty-four eyes from 24 patients with POAG: 11 eyes with preperimetric glaucoma and 13 eyes with early glaucoma received Ganfort ® (bimatoprost + timolol) once a day for a period of 1 month. Before and after the treatment, following measurements were analyzed: IOP, mean ocular perfusion pressure (MOPP), peak time of P50 and amplitude of P50 and N95 waves in PERG (ISCEV standard 2012). Correlations between PERG P50 and N95 waves, IOP and MOPP were calculated. After therapy, IOP significantly decreased in all eyes, on average 31%. Significant increase in MOPP in all eyes on average 14% was detected. PERG amplitude of P50 and N95 waves increased in 75 and 79% eyes, respectively, on average P50 by 28% and N95 by 38%. There were no significant interactions between the change of PERG parameters in time and stage of glaucoma. Significant IOP-lowering therapy can improve RGC function measured by PERG, in patients with preperimetric and early stages of POAG.

Appraisal of Bleb Using Trio of Intraocular Pressure, Morphology on Slit Lamp, and Gonioscopy.

PubMed

Thatte, Shreya; Rana, Rimpi; Gaur, Neeraj

2016-01-01

The aim of this study was to assess bleb function using Wuerzburg bleb classification score (WBCS) for bleb morphology on slit lamp, intraocular pressure (IOP), and gonioscopy. A total of randomly selected 30 eyes posttrabeculectomy were assessed for bleb function with the trio of bleb morphology, IOP, and gonioscopy. Bleb was assessed using the WBCS of 0-12 on slit lamp, IOP was assessed using applanation tonometry, and visualization of inner ostium and iridectomy were assessed using gonioscopy. Postoperative patients of less than six weeks were excluded from the study. The correlation between WBCS and the duration of trabeculectomy was found to be highly significant ( P value = 0.029). The correlation of IOP with WBCS was also found to be strongly positive ( P = 0.000). IOP was found to be highly associated with peripheral iridectomy ( P = 0.000), internal window ( P = 0.001), and bleb characteristics.

The rectenna design on contact lens for wireless powering of the active intraocular pressure monitoring system.

PubMed

Cheng, H W; Jeng, B M; Chen, C Y; Huang, H Y; Chiou, J C; Luo, C H

2013-01-01

This paper proposed a wireless power harvesting system with micro-electro-mechanical-systems (MEMS) fabrication for noninvasive intraocular pressure (IOP) measurement on soft contact lens substructure. The power harvesting IC consists of a loop antenna, an impedance matching network and a rectifier. The proposed IC has been designed and fabricated by CMOS 0.18 um process that operates at the ISM band of 5.8 GHz. The antenna and the power harvesting IC would be bonded together by using flip chip bonding technologies without extra wire interference. The circuit utilized an impedance transformation circuit to boost the input RF signal that improves the circuit performance. The proposed design achieves an RF-to-DC conversion efficiency of 35% at 5.8 GHz.

Use of a 350-mm2 Baerveldt glaucoma drainage device to maintain vision and control intraocular pressure in dogs with glaucoma: a retrospective study (2013-2016).

PubMed

Graham, Kathleen L; Donaldson, David; Billson, Francis A; Billson, F Mark

2017-09-01

To evaluate the 350-mm 2 Baerveldt glaucoma drainage device (GDD) in dogs with refractory glaucoma when modifications to address postoperative hypotony (extraluminal ligature; intraluminal stent) and the fibroproliferative response (intraoperative Mitomycin-C; postoperative oral colchicine and prednisolone) are implemented as reported in human ophthalmology. Retrospective case series. Twenty-eight client-owned dogs (32 eyes) including seven dogs (nine eyes) with primary glaucoma and 21 dogs (23 eyes) with secondary glaucoma. The medical records of all dogs undergoing placement of a 350-mm 2 Baerveldt GDD at a veterinary ophthalmology referral service between 2013 and 2016 were reviewed. Signalment, diagnosis, duration and previous treatment of glaucoma, previous intraocular surgery, IOP, visual, and surgical outcomes were recorded. IOP was maintained <20mmHg in 24 of 32 (75.0%) eyes. Fourteen eyes (43.8%) required no adjunctive treatments to maintain this IOP control. Fewer doses of glaucoma medication were required following surgery. Vision was retained in 18 of 27 (66.7%) eyes with vision at the time of surgery. No eyes that were blind at the time of surgery (n = 5) had restoration of functional vision. Complications following surgery included hypotony (26/32; 81.3%), intraocular hypertension (24/32; 75.0%), and fibrin formation within the anterior chamber (20/32; 62.5%). The average follow-up after placement of the GDD was 361.1 days (median 395.6 days). Efforts to minimize postoperative hypotony and address the fibroproliferative response following placement of a 350-mm 2 Baerveldt GDD showed an increased success rate to other reports of this device in dogs and offers an alternative surgical treatment for controlling intraocular pressure in dogs with glaucoma. © 2016 American College of Veterinary Ophthalmologists.

The real time multi point Thomson scattering diagnostic at NSTX-U

NASA Astrophysics Data System (ADS)

Laggner, Florian; Kolemen, Egemen; Diallo, Ahmed; Leblanc, Benoit; Rozenblat, Roman; Tchilinguirian, Greg; NSTX-U Team Team

2017-10-01

This contribution presents the upgrade of the multi point Thomson scattering (MPTS) diagnostic for real time application. As a key diagnostic at NSTX-U, the MPTS diagnostic simultaneously measures the electron density (ne) and electron temperature (Te) profiles of a plasma discharge. Therefore, this powerful diagnostic can directly access the electron pressure of the plasma. Currently, only post-discharge evaluation of the data is available, however, since the plasma pressure is one important drive for instabilities, real time measurements of this quantities would be beneficial for plasma control. In a first step, ten MPTS channels were equipped with real time electronics, which improve the data acquisition rate by five orders of magnitude. The commissioning of the system is ongoing and first benchmarks of the real time evaluation routines against the standard, post-discharge evaluation show promising results: The Te as well as ne profiles of both types of analyses agree within their uncertainties. This work was supported by the US Department of Energy under DE-SC0015878 and DE-SC0015480.

Intraocular pressure elevation after cataract surgery and its prevention by oral acetazolamide in eyes with pseudoexfoliation syndrome.

PubMed

Hayashi, Ken; Yoshida, Motoaki; Sato, Tatsuhiko; Manabe, Shin-Ichi; Yoshimura, Koichi

2018-02-01

To examine whether intraocular pressure (IOP) increases immediately after cataract surgery in eyes with pseudoexfoliation (PXF) syndrome and to assess whether orally administered acetazolamide can prevent the IOP elevation. Hayashi Eye Hospital, Fukuoka, Japan. Prospective case series. Patients with PXF syndrome scheduled for phacoemulsification were randomly assigned to 1 of 3 groups: (1) oral acetazolamide administered 1 hour preoperatively (preoperative administration group), (2) administered 3 hours postoperatively (postoperative administration group), and (3) not administered (no administration group). The IOP was measured using a rebound tonometer 1 hour preoperatively, upon completion of surgery, and at 1, 3, 5, 7, and 24 hours postoperatively. The study comprised 96 patients (96 eyes). The mean IOP increased at 3, 5, and 7 hours postoperatively in all groups. At 1 hour and 3 hours postoperatively, the IOP was significantly lower in the preoperative administration group than in the postoperative group and no administration group (P ≤ .001). At 5, 7, and 24 hours postoperatively, the IOP was significantly lower in the preoperative group and postoperative administration group than in the no administration group (P ≤. 045). An IOP spike higher than 25 mm Hg occurred less frequently in the preoperative administration group than in the postoperative administration group and the no administration group (P = .038). Intraocular pressure increased at 3, 5, and 7 hours after cataract surgery in eyes with PXF syndrome. Oral acetazolamide administered 1 hour preoperatively reduced the IOP elevation throughout the 24-hour follow-up; acetazolamide administered 3 hours postoperatively reduced the elevation at 5 hours postoperatively and thereafter. Copyright © 2018 ASCRS and ESCRS. Published by Elsevier Inc. All rights reserved.

Relaxin 2 fails to lower intraocular pressure and to dilate retinal vessels in rats.

PubMed

Hampel, Ulrike; Träger, Katharina; Liu, Hanhan; Teister, Julia; Grus, Franz; Prokosch-Willing, Verena

2018-03-13

Recently, the vasodilator relaxin 2 has been introduced as a treatment for acute heart failure. However, its role on vessels of the eye and intraocular pressure (IOP) remains unclear though it has been hypothesized to induce a decrease IOP after intramuscular injection in humans. We aimed to test whether the hormone relaxin 2 lowers IOP and dilates retinal vessels in animals. The IOP of female Sprague-Dawley rats before and after application of relaxin 2 was measured using an Icare Tonolab device calibrated for rats. Recombinant human relaxin 2 in phosphate-buffered saline with 0.1% bovine serum albumin was either applied as eye drops (1000, 2000 or 3000 ng/ml), injected intravitreally (500 ng/ml) or intravenously (13.3 μg/kg body weight). Retinal vessel thickness was monitored using infrared fundus images compiled with optical coherence tomography (Heidelberg Engineering) before and several time points after application of relaxin 2. Neither topical nor intravitreous or intravenous application of relaxin 2 lowered the IOP or changed the arterial or venous vessel diameter after 1 or 3 h after application. Now that relaxin 2 is more easily available, the hormone came again into focus as a potential glaucoma therapeutic. However, our study in rats could not support the hypothesis that relaxin 2 lowers IOP or dilates retinal vessels.

Non-invasive method of measuring cerebral spinal fluid pressure

NASA Technical Reports Server (NTRS)

Borchert, Mark S. (Inventor); Lambert, James L. (Inventor)

2000-01-01

The invention provides a method of non-invasively determining intracranial pressure from measurements of an eye. A parameter of an optic nerve of the eye is determined, along with an intraocular pressure of the eye. The intracranial pressure may be determined from the intraocular pressure and the parameter.

"Fast" Is Not "Real-Time": Designing Effective Real-Time AI Systems

NASA Astrophysics Data System (ADS)

O'Reilly, Cindy A.; Cromarty, Andrew S.

1985-04-01

Realistic practical problem domains (such as robotics, process control, and certain kinds of signal processing) stand to benefit greatly from the application of artificial intelligence techniques. These problem domains are of special interest because they are typified by complex dynamic environments in which the ability to select and initiate a proper response to environmental events in real time is a strict prerequisite to effective environmental interaction. Artificial intelligence systems developed to date have been sheltered from this real-time requirement, however, largely by virtue of their use of simplified problem domains or problem representations. The plethora of colloquial and (in general) mutually inconsistent interpretations of the term "real-time" employed by workers in each of these domains further exacerbates the difficul-ties in effectively applying state-of-the-art problem solving tech-niques to time-critical problems. Indeed, the intellectual waters are by now sufficiently muddied that the pursuit of a rigorous treatment of intelligent real-time performance mandates the redevelopment of proper problem perspective on what "real-time" means, starting from first principles. We present a simple but nonetheless formal definition of real-time performance. We then undertake an analysis of both conventional techniques and AI technology with respect to their ability to meet substantive real-time performance criteria. This analysis provides a basis for specification of problem-independent design requirements for systems that would claim real-time performance. Finally, we discuss the application of these design principles to a pragmatic problem in real-time signal understanding.

Forskolin and rutin prevent intraocular pressure spikes after Nd:YAG laser iridotomy.

PubMed

Nebbioso, M; Belcaro, G; Librando, A; Rusciano, D; Steigerwalt, R D; Pescosolido, N

2012-12-01

the purpose of this research was to evaluate whether an oral treatment with an association of forskolin and rutin can blunt the intraocular pressure (IOP) spikes and avoid the damage that may occur after laser iridotomy. Ten patients underwent bilateral Neodymium:YAG (Nd:YAG) laser iridotomy (Visulas YAG III Laser, Zeiss), for the prevention of primary closed-angle glaucoma. IOP was measured in subjects before and after 7 days of pretreatment with placebo or forskolin and rutin by Goldman applanation tonometry. The IOP was measured before surgery and after surgery at 30-60-120 minutes, and 4-7 days. Analysis of variance indicated a significant increase of the postoperative values in patients receiving treatment with placebo (p < 0.001), but not in those who received treatment with the forskolin and rutin association. T test analysis confirmed that IOP still remained significantly elevated 7 days after laser intervention in placebo treated patients, whereas it stayed within normal values in forskolin/rutin treated patients. Forskolin and rutin can blunt the increase of IOP that occurs after Nd-YAG laser iridotomy. This can avoid serious risk to the optic nerve of the patients under laser treatment for iridotomy.

Twenty-four–Hour Measurement of Intraocular Pressure in Guinea Pigs (Cavia porcellus)

PubMed Central

Ansari-Mood, Maneli; Mehdi-Rajaei, Seyed; Sadjadi, Reza; Selk-Ghaffari, Masoud; Williams, David L

2016-01-01

The objective of this study was to measure intraocular pressure (IOP) in intact, healthy guinea pigs (15 male, 15 female) every 2 h for a 24-h period. First, IOP was measured by using rebound tonometry (RBT). After a 1-min rest period, 0.5% proparacaine ophthalmic solution, a topical anesthetic, was applied to both eyes; 4 min after anesthetic instillation, IOP was measured by using applanation tonometry (APT). The IOP was lower during the light period (0700 to 1900) than during the dark phase (2000 to 0600). The lowest IOP by both RBT and APT (3.68 and 13.37 mm Hg, respectively) occurred at 0700, whereas maximal IOP occurred at 2300 for RBT (8.12 mm Hg) but at 2100 for APT (20.62 mm Hg). No significant differences in IOP between the left and right eyes or between RBT and APT were noted. In addition, daily variations in the IOP of guinea pigs seem to be independent of sex and body weight. The results of this study may be beneficial in the diagnosis and observation of glaucoma in guinea pigs. PMID:26817986

Orbital cerebrospinal fluid space in glaucoma: the Beijing intracranial and intraocular pressure (iCOP) study.

PubMed

Wang, Ningli; Xie, Xiaobin; Yang, Diya; Xian, Junfang; Li, Yong; Ren, Ruojin; Peng, Xiaoxia; Jonas, Jost B; Weinreb, Robert N

2012-10-01

Low cerebrospinal fluid pressure (CSF-P) may be involved in the pathogenesis of glaucoma. We measured the optic nerve subarachnoid space width (ONSASW) as a surrogate for orbital CSF-P in patients with primary open-angle glaucoma (POAG) with normal and high pressure and a control group. Prospective observational study. The study included 39 patients with POAG; 21 patients had normal pressure (intraocular pressure [IOP] 21 mmHg), and 18 patients had high pressure (IOP >21 mmHg); 21 subjects formed the control group. By using magnetic resonance imaging (MRI) with fat-suppressed fast recovery fast spin echo (FRFSE) T2-weighted sequence, we determined the ONSASW at 3, 9, and 15 mm posterior to the globe. The ONSASW and optic nerve diameter. At all 3 measurement locations of 3, 9, and 15 mm, the ONSASW was significantly (P<0.001, P<0.001, and P = 0.003, respectively) narrower in the normal-pressure group (0.67±0.16, 0.55±0.09, and 0.51±0.12 mm, respectively) than in the high-pressure group (0.93±0.21, 0.70±0.12, and 0.62±0.11 mm, respectively) or the control group (0.87±0.15, 0.67±0.07, and 0.61±0.07 mm, respectively). The high-pressure and control groups did not vary significantly at 3, 9, and 15 mm (P = 0.31, P = 0.39, and P = 0.44, respectively). At all 3 measurement locations, ONSASW was narrower in the normal-pressure group compared with the high-pressure and control groups after adjustment for optic nerve diameter (P<0.01). Correspondingly, the width of the optic nerve subarachnoid space measured at 3, 9, and 15 mm behind the globe, respectively, was significantly (all P<0.05) associated with IOP after adjustment for optic nerve diameter and visual field defect. The narrower orbital optic nerve subarachnoid space in patients with POAG with normal pressure compared with high pressure suggests a lower orbital CSF-P in patients with POAG with normal pressure. Copyright © 2012 American Academy of Ophthalmology. Published by Elsevier Inc. All rights reserved.

Long-term effect of anti-vascular endothelial growth factor injections on intraocular pressure

PubMed Central

Nariani, Ashiyana; Williams, Blake; Hariprasad, Seenu M

2016-01-01

Objective: There is a substantial debate in the ophthalmology community about whether anti-vascular endothelial growth factor (VEGF) injections result in a long-term increase in intraocular pressure (IOP). Design: We performed a retrospective study to investigate how the number and timing of intravitreal injections in patients with age-related macular degeneration (AMD) and diabetic macular edema (DME) affect IOP over time. Methods: We collected long-term IOP data on patients receiving anti-VEGF injections at our institution. Patients over the age of 40 years who received injections for AMD (n = 76) or DME (n = 55) were included. Patients were grouped according to indication as well as number of injections received (1–3, 4–6, 7–9, or 10+ injections). IOP measurements were then placed into time points (0–6, 6–12, 12–18, 18–24, or 24+ months) and compared to the preinjection average IOP. Results: For patients with DME, average preinjection IOP was 15.7 mmHg. At 24+ months after injection, the average IOP was 15.2 (P = 0.68) for patients receiving 1–3 injections, 16.8 (P = 0.23) for 4–6 injections, and 14.4 (P = 0.66) for 7–9 injections. For patients with AMD, average initial IOP was 15.6 mmHg. At 24+ months after injection, the average IOP was 12.6 (P = 0.97) for 1–3 injections, 14.9 (P = 0.96) for 4–6 injections, 14.8 (P = 0.84) for 7–9 injections, and 15.7 (P = 0.56) for 10+ injections. Conclusions: There was no increase in IOP over time for AMD or DME patients, regardless of how many injections they received. For patients receiving unilateral injections, there was no increase in IOP in the injected eye when compared to the noninjected eye. PMID:27853011

MicroRNA profiling in intraocular medulloepitheliomas.

PubMed

Edward, Deepak P; Alkatan, Hind; Rafiq, Qundeel; Eberhart, Charles; Al Mesfer, Saleh; Ghazi, Nicola; Al Safieh, Leen; Kondkar, Altaf A; Abu Amero, Khaled K

2015-01-01

To study the differential expression of microRNA (miRNA) profiles between intraocular medulloepithelioma (ME) and normal control tissue (CT). Total RNA was extracted from formalin fixed paraffin embedded (FFPE) intraocular ME (n=7) and from age matched ciliary body controls (n=8). The clinical history and phenotype was recorded. MiRNA profiles were determined using the Affymetrix GeneChip miRNA Arrays analyzed using expression console 1.3 software. Validation of significantly dysregulated miRNA was confirmed by quantitative real-time PCR. The web-based DNA Intelligent Analysis (DIANA)-miRPath v2.0 was used to perform enrichment analysis of differentially expressed (DE) miRNA gene targets in Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway. The pathologic evaluation revealed one benign (benign non-teratoid, n=1) and six malignant tumors (malignant teratoid, n=2; malignant non-teratoid, n = 4). A total of 88 miRNAs were upregulated and 43 miRNAs were downregulated significantly (P<0.05) in the tumor specimens. Many of these significantly dysregulated miRNAs were known to play various roles in carcinogenesis and tumor behavior. RT-PCR validated three significantly upregulated miRNAs and three significantly downregulated miRNAs namely miR-217, miR-216a, miR-216b, miR-146a, miR-509-3p and miR-211. Many DE miRNAs that were significant in ME tumors showed dysregulation in retinoblastoma, glioblastoma, and precursor, normal and reactive human cartilage. Enriched pathway analysis suggested a significant association of upregulated miRNAs with 15 pathways involved in prion disease and several types of cancer. The pathways involving significantly downregulated miRNAs included the toll-like receptor (TLR) (p<4.36E-16) and Nuclear Factor kappa B (NF-κB) signaling pathways (p<9.00E-06). We report significantly dysregulated miRNAs in intraocular ME tumors, which exhibited abnormal profiles in other cancers as well such as retinoblastoma and glioblastoma. Pathway analysis of

Intraocular pressure in clinically normal dromedary camels (Camelus dromedarius).

PubMed

Marzok, Mohamed A; El-Khodery, Sabry A

2015-02-01

To determine the intraocular pressure (IOP) in healthy dromedary camels (Camelus dromedarius). 24 clinically normal dromedary camels. For each camel, the IOP of both eyes was measured with applanation tonometry. Three measurements with < 5% variance were obtained for each eye on the same day of the week for 3 consecutive weeks. Mean IOP was calculated for each eye on each day for comparison purposes. Mean ± SD IOPs for the right (31.1 ± 2.1 mm Hg) and left (30.8 ± 1.9 mm Hg) eyes of immature camels were significantly higher than those for the right (27.1 ± 1.2 mm Hg) and left (28.2 ± 1.2 mm Hg) eyes of mature camels. Intra-assay and interassay coefficients of variation (CVs) for IOP measurements of the right and left eyes did not differ significantly between immature and mature camels. Interassay CVs of IOP measurements for the right and left eyes ranged from 1.5% to 12.1% and 1.2% to 10.3%, respectively, for immature camels and from 1.2% to 17.2% and 1.7% to 18.8%, respectively, for mature camels. Intra-assay CVs of IOP measurements for the right and left eyes ranged from 1.5% to 10.6% and 1.9% to 9.6%, respectively, for immature camels and from 2.8% to 16.9% and 2.7% to 12.4%, respectively, for mature camels. Age was negatively correlated (r = -0.403) with IOP. Results provided a reference and might aid in the diagnosis of glaucoma and uveitis during complete ophthalmic examinations of dromedary camels.

Optical eye tracking system for real-time noninvasive tumor localization in external beam radiotherapy.

PubMed

Via, Riccardo; Fassi, Aurora; Fattori, Giovanni; Fontana, Giulia; Pella, Andrea; Tagaste, Barbara; Riboldi, Marco; Ciocca, Mario; Orecchia, Roberto; Baroni, Guido

2015-05-01

External beam radiotherapy currently represents an important therapeutic strategy for the treatment of intraocular tumors. Accurate target localization and efficient compensation of involuntary eye movements are crucial to avoid deviations in dose distribution with respect to the treatment plan. This paper describes an eye tracking system (ETS) based on noninvasive infrared video imaging. The system was designed for capturing the tridimensional (3D) ocular motion and provides an on-line estimation of intraocular lesions position based on a priori knowledge coming from volumetric imaging. Eye tracking is performed by localizing cornea and pupil centers on stereo images captured by two calibrated video cameras, exploiting eye reflections produced by infrared illumination. Additionally, torsional eye movements are detected by template matching in the iris region of eye images. This information allows estimating the 3D position and orientation of the eye by means of an eye local reference system. By combining ETS measurements with volumetric imaging for treatment planning [computed tomography (CT) and magnetic resonance (MR)], one is able to map the position of the lesion to be treated in local eye coordinates, thus enabling real-time tumor referencing during treatment setup and irradiation. Experimental tests on an eye phantom and seven healthy subjects were performed to assess ETS tracking accuracy. Measurements on phantom showed an overall median accuracy within 0.16 mm and 0.40° for translations and rotations, respectively. Torsional movements were affected by 0.28° median uncertainty. On healthy subjects, the gaze direction error ranged between 0.19° and 0.82° at a median working distance of 29 cm. The median processing time of the eye tracking algorithm was 18.60 ms, thus allowing eye monitoring up to 50 Hz. A noninvasive ETS prototype was designed to perform real-time target localization and eye movement monitoring during ocular radiotherapy treatments. The

Acetylsalicylic acid does not reduce the intraocular pressure variation in ocular hypertension or glaucoma.

PubMed

Lindén, C; Alm, A

2000-03-01

The purpose of this study was to measure if intraocular pressure (IOP) and IOP variations in patients with ocular hypertension and glaucoma are decreased by acetylsalicylic acid (ASA). The hypothesis to be tested was that short-term fluctuations in the IOP are caused by breaks of the inner wall of Schlemm's canal that are repaired by platelets inducing a cycle of breaks and repair. Furthermore, prostaglandins affect uveoscleral outflow and ASA inhibits prostaglandin biosynthesis and platelet aggregation. This implies that ASA may have complex effects on the IOP and its variations.In 28 patients with ocular hypertension or glaucoma the IOP was measured seven times during 2 hr on two succeeding days. Five hundred mg ASA or placebo was administrated orally in a masked fashion 15 hr prior to the second session. After wash-out, this procedure was repeated with a cross-over design. The same study outline was used in 28 glaucoma patients except for the cross-over design. There were no statistically significant differences in the mean IOP or in the IOP variations between the placebo treated and the ASA treated eyes in either group, and there were no significant differences between the day before and after treatment in any group. The results suggest that ASA does not affect IOP variations in a clinically significant way and that a single dose of ASA has no significant effect on mean IOP. Copyright 2000 Academic Press.

Intraocular (Eye) Melanoma—Health Professional Version

Cancer.gov

Intraocular (uveal) melanoma of the uveal tract (iris, ciliary body, and choroid), though rare, is the most common primary intraocular malignancy in adults. Find evidence-based information on intraocular melanoma treatment.

Effect of changes in PCO2 and body positions on intraocular pressure during general anaesthesia.

PubMed

Hvidberg, A; Kessing, S V; Fernandes, A

1981-08-01

Elevated arterial carbon dioxide tension, induced by the administration of CO2 via the respiratory air or by hypoventilation, entailed a gradual increase in the IOP in patients without eye diseases under general anaesthesia. A sudden cessation of CO2 administration or hyperventilation caused such a rapid, simultaneous fall in IOP to values below the initial level that the pressure variations must be of vascular nature, presumably related to changes in choroidal blood volume. The above-mentioned procedures always cause a change in the central venous pressure (CVP) simultaneously with the IOP changes. Alterations of the CVP induced by hydrostatic factors in postural changes, placing the head 15 degrees above or below the horizontal level while keeping the PaCO2 constant, caused IOP changes of the same configuration and magnitude as described above. It is concluded, therefore, that presumably the CO2-conditioned IOP changes are due predominantly to changes in central venous pressure, being one link in a CO2-conditioned action upon the general circulation, entailing passive secondary changes in the choroidal venous blood volume and thereby an influence upon the IOP. On the basis of the present results it appears rational to recommend hyperventilation to keep the PaCO2 between 25 and 30 mm and a 15 degree anti-Trendelenburg position in operations on the eye under general anaesthesia, since both procedures afford a low central venous pressure and consequently a low pressure in the posterior segment of the eye, with its attendant advantages as regards vitreous complications and the insertion of intraocular lenses. Owing to the risk of an unacceptable fall in BP in the combined procedure, a frequent checking of the BP is needed.

Predictors of intraocular pressure change after phacoemulsification in patients with pseudoexfoliation syndrome.

PubMed

Moghimi, Sasan; Johari, Mohammadkarim; Mahmoudi, Alireza; Chen, Rebecca; Mazloumi, Mehdi; He, Mingguang; Lin, Shan C

2017-03-01

To evaluate anterior chamber biometric factors and intraoperative metrics associated with the intraocular pressure (IOP) reduction after phacoemulsification in non-glaucomatous pseudoexfoliative syndrome (PXS) eyes. Thirty-three patients were enrolled in this prospective interventional study. Images were excluded if they had poor quality, poor perpendicularity or inability to locate sclera spurs. Anterior chamber depth (ACD), anterior chamber area (ACA), iris thickness, iris area, iris curvature, lens vault, angle opening distance (AOD500, AOD750) and trabecular iris space area (TISA500, TISA750) were measured in qualified images using the Zhongshan Angle Assessment Program and compared preoperatively and 3 months postoperatively. Cumulative dissipated energy (CDE), aspiration time and infusion fluid usage during cataract surgery were obtained from the phacoemulsification machine's metrics record. Postoperative IOP change was compared with these anatomical and intraoperative metric parameters. Mean IOP was 18.1±3.4 mm Hg preoperatively and decreased by 3.3 mm Hg (18%) to 14.8±3.6 mm Hg at 3 months postoperatively (p<0.001). All angle parameters, ACD and ACA increased significantly postoperatively (p<0.001 for all) and iris curvature decreased (p<0.001). In univariate analysis, preoperative IOP (B=-0.668, p=0.002), infusion fluid usage (B=-0.040, p=0.04) and aspiration time (B=-0.045, p=0.003) were negatively associated with IOP decrease after phacoemulsification. Changes in IOP did not demonstrate significant associations with CDE measurements or anterior segment optical coherence tomography measurements, including preoperative angle, iris or anterior segment parameters. In the final multivariate regression model, preoperative IOP (B=-0.668, p=0.002) and infusion fluid usage (B=-0.041, p=0.04) were significantly associated with IOP drop and together can predict 45.1% (p=0.002) of the variability in IOP change. Non-glaucomatous patients with PXS

Fitness Level Modulates Intraocular Pressure Responses to Strength Exercises.

PubMed

Vera, Jesús; Jiménez, Raimundo; Redondo, Beatríz; Cárdenas, David; García-Ramos, Amador

2018-06-01

Purpose/Aim: The execution of strength exercises has demonstrated to increase the intraocular pressure (IOP) levels, and it may have a negative impact on the ocular health. We aimed to explore the influence of fitness level on the acute IOP response to strength exercises performed under different loading conditions, as well as to test whether the IOP responses differ between the bench press and jump squat when performed against the same relative loads. Forty military personnel males were divided in two subgroups (20 high-fit and 20 low-fit) based on their relative to body mass one-repetition maximum (1-RM). Participants performed an incremental loading test in the bench press and jump squat exercises, and IOP was assessed before and after each repetition by rebound tonometry. IOP increased immediately after executing both exercises (p < 0.01 in both cases), being the magnitude of the IOP increment positively and linearly associated with the increment of the load in both groups (i.e., high-fit and low-fit) and in both exercises (R 2 range: 0.81-1.00). Higher fitness level attenuated the IOP rise produced by both exercises (p < 0.01 in both cases). The bench press induced higher IOP increments than the jump squat for both groups at relative loads of ~50%1-RM and ~60%1-RM (p < 0.01 in all cases). These data indicate that IOP increases as a consequence of performing strength exercises, being the increment accentuated with the increase of the load and in the bench press compared to the jump squat exercise. Of special importance would be that the IOP responses were significantly reduced in high-fit individuals. These findings should be addressed in glaucoma patients.

Tsunami simulation method initiated from waveforms observed by ocean bottom pressure sensors for real-time tsunami forecast; Applied for 2011 Tohoku Tsunami

NASA Astrophysics Data System (ADS)

Tanioka, Yuichiro

2017-04-01

After tsunami disaster due to the 2011 Tohoku-oki great earthquake, improvement of the tsunami forecast has been an urgent issue in Japan. National Institute of Disaster Prevention is installing a cable network system of earthquake and tsunami observation (S-NET) at the ocean bottom along the Japan and Kurile trench. This cable system includes 125 pressure sensors (tsunami meters) which are separated by 30 km. Along the Nankai trough, JAMSTEC already installed and operated the cable network system of seismometers and pressure sensors (DONET and DONET2). Those systems are the most dense observation network systems on top of source areas of great underthrust earthquakes in the world. Real-time tsunami forecast has depended on estimation of earthquake parameters, such as epicenter, depth, and magnitude of earthquakes. Recently, tsunami forecast method has been developed using the estimation of tsunami source from tsunami waveforms observed at the ocean bottom pressure sensors. However, when we have many pressure sensors separated by 30km on top of the source area, we do not need to estimate the tsunami source or earthquake source to compute tsunami. Instead, we can initiate a tsunami simulation from those dense tsunami observed data. Observed tsunami height differences with a time interval at the ocean bottom pressure sensors separated by 30 km were used to estimate tsunami height distribution at a particular time. In our new method, tsunami numerical simulation was initiated from those estimated tsunami height distribution. In this paper, the above method is improved and applied for the tsunami generated by the 2011 Tohoku-oki great earthquake. Tsunami source model of the 2011 Tohoku-oki great earthquake estimated using observed tsunami waveforms, coseimic deformation observed by GPS and ocean bottom sensors by Gusman et al. (2012) is used in this study. The ocean surface deformation is computed from the source model and used as an initial condition of tsunami

Noninvasive photoacoustic detecting intraocular foreign bodies with an annular transducer array.

PubMed

Yang, Diwu; Zeng, Lvming; Pan, Changning; Zhao, Xuehui; Ji, Xuanrong

2013-01-14

We present a fast photoacoustic imaging system based on an annular transducer array for detection of intraocular foreign bodies. An eight-channel data acquisition system is applied to capture the photoacoustic signals using multiplexing and the total time of data acquisition and transferring is within 3 s. A limited-view filtered back projection algorithm is used to reconstruct the photoacoustic images. Experimental models of intraocular metal and glass foreign bodies were constructed on ex vivo pig's eyes and clear photoacoustic images of intraocular foreign bodies were obtained. Experimental results demonstrate the photoacoustic imaging system holds the potential for in clinic detecting the intraocular foreign bodies.

Real-time 3-dimensional contrast-enhanced ultrasound in detecting hemorrhage of blunt renal trauma.

PubMed

Xu, Rui-Xue; Li, Ye-Kuo; Li, Ting; Wang, Sha-Sha; Yuan, Gui-Zhong; Zhou, Qun-Fang; Zheng, Hai-Rong; Yan, Fei

2013-10-01

The objective of this study is to evaluate the diagnostic value of real-time 3-dimensional contrast-enhanced ultrasound in the hemorrhage of blunt renal trauma. Eighteen healthy New Zealand white rabbits were randomly divided into 3 groups. Blunt renal trauma was performed on each group by using minitype striker. Ultrasonography, color Doppler flow imaging, and contrast-enhanced 2-dimensional and real-time 3-dimensional ultrasound were applied before and after the strike. The time to shock and blood pressure were subjected to statistical analysis. Then, a comparative study of ultrasound and pathology was carried out. All the struck kidneys were traumatic. In the ultrasonography, free fluid was found under the renal capsule. In the color Doppler flow imaging, active hemorrhage was not identified. In 2-dimensional contrast-enhanced ultrasound, active hemorrhage of the damaged kidney was characterized. Real-time 3-dimensional contrast-enhanced ultrasound showed a real-time and stereoscopic ongoing bleeding of the injured kidney. The wider the hemorrhage area in 4-dimensional contrast-enhanced ultrasound was, the faster the blood pressure decreased. Real-time 3-dimensional contrast-enhanced ultrasound is a promising noninvasive tool for stereoscopically and vividly detecting ongoing hemorrhage of blunt renal trauma in real time. © 2013.

Glaucoma filtration surgery following sustained elevation of intraocular pressure secondary to intravitreal anti-VEGF injections.

PubMed

Skalicky, Simon E; Ho, Ivan; Agar, Ashish; Bank, Allan

2012-07-01

To document cases of sustained elevation of intraocular pressure (IOP) while receiving intravitreal anti-vascular endothelial growth factor (VEGF) agents and subsequent management. A retrospective series of all cases managed by the authors and colleagues was performed. Six patients developed sustained elevated IOP; five received ranibizumab and one bevacizumab. Four received unilateral and two received bilateral injections. Two had preexisting primary open-angle glaucoma and one had pseudoexfoliative glaucoma, all with stable IOP prior to anti-VEGF treatment. Angles were open in all cases. Peak IOP averaged 43 mm Hg (range: 34 to 60 mm Hg). The mean number of injections preceding the IOP increase was 10 (range: 1 to 20). Four patients required trabeculectomy, one selective laser trabeculoplasty, and one multiple topical medications. A sustained increase in IOP requiring glaucoma filtering surgery is a rare but important treatment complication for patients receiving intravitreal anti-VEGF therapy, especially those with preexisting glaucoma or glaucoma risk factors. Copyright 2012, SLACK Incorporated.

Severe pigment dispersion after iris-claw phakic intraocular lens implantation.

PubMed

Galvis, Virgilio; Carreño, Néstor I; Tello, Alejandro; Laiton, Andrea N

2017-12-01

A 23-year-old female patient presented 3 months after the implantation of an Artisan® phakic intraocular lens with a severe depigmentation of the iris and peripheral anterior synechiae. Explantation of the intraocular lens and goniosynechialysis were performed. Eleven months after the explantation appearance of the iris significantly improved. There was no loss of lines of corrected distance visual acuity. Severe pigment dispersion after the implantation of an Artisan® phakic intraocular lens may happen and may require explantation of the lens. Iris depigmentation may improve with time.

The measurement of intraocular pressure over positive soft contact lenses by rebound tonometry.

PubMed

Zeri, Fabrizio; De Cusatis, Mario; Lupelli, Luigi; Swann, Peter Graham

2016-01-01

To investigate if the accuracy of intraocular pressure (IOP) measurements using rebound tonometry over disposable hydrogel (etafilcon A) contact lenses (CL) is affected by the positive power of the CLs. The experimental group comprised 26 subjects, (8 male, 18 female). IOP measurements were undertaken on the subjects' right eyes in random order using a Rebound Tonometer (ICare). The CLs had powers of +2.00D and +6.00D. Measurements were taken over each contact lens and also before and after the CLs had been worn. The IOP measure obtained with both CLs was significantly lower compared to the value without CLs (t test; p<0.001) but no significant difference was found between the two powers of CLs. Rebound tonometry over positive hydrogel CLs leads to a certain degree of IOP underestimation. This result did not change for the two positive lenses used in the experiment, despite their large difference in power and therefore in lens thickness. Optometrists should bear this in mind when measuring IOP with the rebound tonometer over plus power contact lenses. Copyright © 2016 The Authors. Published by Elsevier Espana.. All rights reserved.

Genetics of Primary Intraocular Tumors

PubMed Central

Nagarkatti-Gude, Nisha; Wang, Yujuan; Ali, Mohammad Javed; Honavar, Santosh G.; Jager, Martine J.; Chan, Chi-Chao

2012-01-01

Primary intraocular neoplasms are tumors that originate within the eye. The most common malignant primary intraocular tumor in adults is uveal melanoma and the second is primary intraocular lymphoma or vitreoretinal (intraocular) lymphoma. The most common malignant intraocular tumor in children is retinoblastoma. Genetics plays a vital role in the diagnosis and detection of ocular tumors. In uveal melanoma, monosomy 3 is the most common genetic alteration and somatic mutations of BAP1, a tumor suppressor gene, have been reported in nearly 50% of primary uveal melanomas. The retinoblastoma gene RB1 is the prototype tumor suppressor gene—mutations in RB1 alleles lead to inactivated RB protein and the development of retinoblastoma. Immunoglobulin heavy chain (IgH) or T-cell receptor (TCR) gene rearrangement is observed in B-cell or T-cell primary vitreoretinal lymphoma, respectively. Other factors related to the genetics of these three common malignancies in the eye are discussed and reviewed. PMID:22834783

Low first postoperative day intraocular pressure as a positive prognostic indicator in deep sclerectomy.

PubMed

Shaarawy, T; Flammer, J; Smits, G; Mermoud, A

2004-05-01

To study the possibility of using intraocular pressure (IOP) in the first postoperative day after sclerectomy as a prognostic indicator. Non-randomised prospective trial involving 105 eyes of 105 patients with medically uncontrolled primary and secondary open angle glaucoma. Visual acuity, IOP, and slit lamp examinations were performed before and after surgery at 1 and 7 days, and 1, 3, 6, 9, 12, 18, 24, 30, 36, 48, 54, 60, and 66 months. Visual field examinations were repeated every 6 months. A split point on day 1 IOP of less than or equal to 5 mm Hg (61%) versus more than 5 mm Hg (39%) was used. The first postoperative day IOP was examined in relation to the need for subsequent Nd:YAG goniopuncture, the subsequent use of postoperative antiglaucoma medications, and as a stratification variable in the Kaplan-Meier analyses. The mean follow up was 43.2 (SD 14.3) months. The mean preoperative IOP was 26.8 (SD 7.7) mm Hg; the mean postoperative IOP was 5.1 (3.3) mm Hg at day 1 and 11.8 (3.1) mm Hg at month 60. Patients with IOP time to failure was 24 months (95% CI: 12 to 30), but for those with an IOP >5 mm Hg, the median time to failure was only 6 months (CI 2 to 9). No significant difference in postoperative antiglaucoma medications was observed. First postoperative day IOP can be considered to be a significant prognostic indicator in deep sclerectomy.

Effect of high pressurization versus normal pressurization on changes in intraocular pressure immediately after clear corneal cataract surgery.

PubMed

Hayashi, Ken; Yoshida, Motoaki; Manabe, Shin-Ichi; Yoshimura, Koichi

2014-01-01

To compare changes in intraocular pressure (IOP) immediately after clear corneal incision (CCI) cataract surgery between eyes in which IOP was adjusted to a high or normal range at the conclusion of surgery. Hayashi Eye Hospital, Fukuoka, Japan. Comparative case series. Either eye of patients scheduled for phacoemulsification was randomized to 1 of 2 groups as follows: eyes that were to be adjusted to (1) high IOP (22 to 40 mm Hg) or (2) normal IOP (10 to 21 mm Hg). The IOP was measured using a rebound tonometer preoperatively; at the conclusion of surgery; and 15, 30, 60, 120, and 180 minutes and 24 hours postoperatively. The Seidel test and anterior segment optical coherence tomography (AS-OCT) were performed. The mean IOP at the conclusion of surgery was 31.3 mm Hg in the high IOP group and 17.1 mm Hg in the normal IOP group. The IOP decreased to approximately 15 mm Hg by 15 minutes and did not change until 60 minutes in either group. The mean IOP did not differ significantly between groups throughout the observation period (P ≥.0634). Hypotony of 5 mm Hg or less was not detected in any eye. The Seidel test was negative and based on AS-OCT, the wound was closed at 60 minutes in all eyes. After adjusting IOP to a high or normal range, the IOP normalized within 15 minutes postoperatively and was stable for 24 hours. The wound was closed within 60 minutes postoperatively. Copyright © 2013 ASCRS and ESCRS. Published by Elsevier Inc. All rights reserved.

Dependable Real-Time Systems

DTIC Science & Technology

1991-09-30

0196 or 413 545-0720 PI E-mail Address: krithi@nirvan.cs.umass.edu, stankovic(ocs.umass.edu Grant or Contract Title: Dependable Real - Time Systems Grant...Dependable Real - Time Systems " Grant or Contract Number: N00014-85-k-0398 L " Reporting Period: 1 Oct 87 - 30 Sep 91 , 2. Summary of Accomplishments ’ 2.1 Our...in developing a sound approach to scheduling tasks in complex real - time systems , (2) developed a real-time operating system kernel, a preliminary

Clinical investigation of the effect of topical anesthesia on intraocular pressure

PubMed Central

Almubrad, Turki M; Ogbuehi, Kelechi C

2007-01-01

Background/Aims: Contact tonometry is generally considered more accurate than non-contact tonometry in the assessment of intraocular pressure (IOP). This study was designed to investigate the effect of ocular anesthesia, a pre-requisite for contact tonometry, on the IOP in a sample of visually normal subjects. Method: In a random sample of 120 young visually normal subjects (divided equally among three groups), the Topcon CT80 non-contact tonometer was used to measure IOP before, at the second minute and at the fifth minute following instillation of one drop of one of three eyedrops – carboxymethylcellulose sodium 0.5% (control), oxybuprocaine hydrochloride 0.4% and proparacaine hydrochloride 0.5%. Results: The IOP measured before instilling the ophthalmic drops did not vary significantly among the three groups of subjects (p > 0.05). In the control group, the average IOP of 15.1 ± 2.6 mmHg did not vary significantly (p > 0.05) 2 minutes and 5 minutes following instillation of one drop of Carboxymethylcellulose sodium. There were statistically significant reductions of IOP 2 minutes (p < 0.01) and 5 minutes (p < 0.001) after the instillation of one drop of oxybuprocaine hydrochloride. One drop of proparacaine hydrochloride caused significant reductions in the average IOP after 2 minutes (p < 0.001) and after 5 minutes (p < 0.001). Conclusions: One drop of topical proparacaine or oxybuprocaine may cause a small but a statistically significant reduction in IOP which could lead to lower IOP readings. PMID:19668485

Clinical investigation of the effect of topical anesthesia on intraocular pressure.

PubMed

Almubrad, Turki M; Ogbuehi, Kelechi C

2007-09-01

Contact tonometry is generally considered more accurate than non-contact tonometry in the assessment of intraocular pressure (IOP). This study was designed to investigate the effect of ocular anesthesia, a pre-requisite for contact tonometry, on the IOP in a sample of visually normal subjects. In a random sample of 120 young visually normal subjects (divided equally among three groups), the Topcon CT80 non-contact tonometer was used to measure IOP before, at the second minute and at the fifth minute following instillation of one drop of one of three eyedrops - carboxymethylcellulose sodium 0.5% (control), oxybuprocaine hydrochloride 0.4% and proparacaine hydrochloride 0.5%. The IOP measured before instilling the ophthalmic drops did not vary significantly among the three groups of subjects (p > 0.05). In the control group, the average IOP of 15.1 +/- 2.6 mmHg did not vary significantly (p > 0.05) 2 minutes and 5 minutes following instillation of one drop of Carboxymethylcellulose sodium. There were statistically significant reductions of IOP 2 minutes (p < 0.01) and 5 minutes (p < 0.001) after the instillation of one drop of oxybuprocaine hydrochloride. One drop of proparacaine hydrochloride caused significant reductions in the average IOP after 2 minutes (p < 0.001) and after 5 minutes (p < 0.001). One drop of topical proparacaine or oxybuprocaine may cause a small but a statistically significant reduction in IOP which could lead to lower IOP readings.

Unprocessed real-time imaging of vitreoretinal surgical maneuvers using a microscope-integrated spectral-domain optical coherence tomography system.

PubMed

Hahn, Paul; Migacz, Justin; O'Connell, Rachelle; Izatt, Joseph A; Toth, Cynthia A

2013-01-01

We have recently developed a microscope-integrated spectral-domain optical coherence tomography (MIOCT) device towards intrasurgical cross-sectional imaging of surgical maneuvers. In this report, we explore the capability of MIOCT to acquire real-time video imaging of vitreoretinal surgical maneuvers without post-processing modifications. Standard 3-port vitrectomy was performed in human during scheduled surgery as well as in cadaveric porcine eyes. MIOCT imaging of human subjects was performed in healthy normal volunteers and intraoperatively at a normal pause immediately following surgical manipulations, under an Institutional Review Board-approved protocol, with informed consent from all subjects. Video MIOCT imaging of live surgical manipulations was performed in cadaveric porcine eyes by carefully aligning B-scans with instrument orientation and movement. Inverted imaging was performed by lengthening of the reference arm to a position beyond the choroid. Unprocessed MIOCT imaging was successfully obtained in healthy human volunteers and in human patients undergoing surgery, with visualization of post-surgical changes in unprocessed single B-scans. Real-time, unprocessed MIOCT video imaging was successfully obtained in cadaveric porcine eyes during brushing of the retina with the Tano scraper, peeling of superficial retinal tissue with intraocular forceps, and separation of the posterior hyaloid face. Real-time inverted imaging enabled imaging without complex conjugate artifacts. MIOCT is capable of unprocessed imaging of the macula in human patients undergoing surgery and of unprocessed, real-time, video imaging of surgical maneuvers in model eyes. These capabilities represent an important step towards development of MIOCT for efficient, real-time imaging of manipulations during human surgery.

Treatment carryover impacts on effectiveness of intraocular pressure lowering agents, estimated by a discrete event simulation model.

PubMed

Denis, P; Le Pen, C; Umuhire, D; Berdeaux, G

2008-01-01

To compare the effectiveness of two treatment sequences, latanoprost-latanoprost timolol fixed combination (L-LT) versus travoprost-travoprost timolol fixed combination (T-TT), in the treatment of open-angle glaucoma (OAG) or ocular hypertension (OHT). A discrete event simulation (DES) model was constructed. Patients with either OAG or OHT were treated first-line with a prostaglandin, either latanoprost or travoprost. In case of treatment failure, patients were switched to the specific prostaglandin-timolol sequence LT or TT. Failure was defined as intraocular pressure higher than or equal to 18 mmHg at two visits. Time to failure was estimated from two randomized clinical trials. Log-rank tests were computed. Linear functions after log-log transformation were used to model time to failure. The time horizon of the model was 60 months. Outcomes included treatment failure and disease progression. Sensitivity analyses were performed. Latanoprost treatment resulted in more treatment failures than travoprost (p<0.01), and LT more than TT (p<0.01). At 60 months, the probability of starting a third treatment line was 39.2% with L-LT versus 29.9% with T-TT. On average, L-LT patients developed 0.55 new visual field defects versus 0.48 for T-TT patients. The probability of no disease progression at 60 months was 61.4% with L-LT and 65.5% with T-TT. Based on randomized clinical trial results and using a DES model, the T-TT sequence was more effective at avoiding starting a third line treatment than the L-LT sequence. T-TT treated patients developed less glaucoma progression.

Effects of diurnal variation and anesthetic agents on intraocular pressure in Syrian hamsters (Mesocricetus auratus).

PubMed

Rajaei, Seyed Mehdi; Mood, Maneli Ansari; Paryani, Mohammad Reza; Williams, David L

2017-01-01

OBJECTIVE To determine effects of diurnal variation and anesthetic agents on intraocular pressure (IOP) in Syrian hamsters (Mesocricetus auratus). ANIMALS 90 healthy adult Syrian hamsters (45 males and 45 females). PROCEDURES IOP was measured with a rebound tonometer. In phase 1, IOP was measured in all hamsters 3 times during a 24-hour period (7 am, 3 pm, and 11 pm). In phase 2, hamsters were assigned to 5 groups (18 animals [9 males and 9 females]/group). Each group received an anesthetic agent or combination of anesthetic agents (ketamine hydrochloride, xylazine hydrochloride, diazepam, ketamine-diazepam [KD], or ketamine-xylazine [KX] groups) administered via the IP route. The IOP was measured before (time 0 [baseline]) and 10, 30, 60, 90, 120, and 150 minutes after administration of drugs. RESULTS Mean ± SD IOP values were 2.58 ± 0.87 mm Hg, 4.46 ± 1.58 mm Hg, and 5.96 ± 1.23 mm Hg at 7 am, 3 pm, and 11 pm, respectively. Mean baseline IOP was 6.25 ± 0.28 mm Hg, 6.12 ± 0.23 mm Hg, 5.75 ± 0.64 mm Hg, 5.12 ± 1.40 mm Hg, and 4.50 ± 1.30 mm Hg for the ketamine, xylazine, diazepam, KD, and KX groups, respectively. A significant decrease in IOP, compared with baseline IOP, was detected in only the KX group at 30, 60, and 90 minutes after drug administration. CONCLUSIONS AND CLINICAL RELEVANCE Maximum IOP in Syrian hamsters was detected at night. The ketamine-xylazine anesthetic combination significantly decreased IOP in Syrian hamsters.

Selective loss of orientation column maps in visual cortex during brief elevation of intraocular pressure.

PubMed

Chen, Xin; Sun, Chao; Huang, Luoxiu; Shou, Tiande

2003-01-01

To compare the orientation column maps elicited by different spatial frequency gratings in cortical area 17 of cats before and during brief elevation of intraocular pressure (IOP). IOP was elevated by injecting saline into the anterior chamber of a cat's eye through a syringe needle. The IOP was elevated enough to cause a retinal perfusion pressure (arterial pressure minus IOP) of approximately 30 mm Hg during a brief elevation of IOP. The visual stimulus gratings were varied in spatial frequency, whereas other parameters were kept constant. The orientation column maps of the cortical area 17 were monocularly elicited by drifting gratings of different spatial frequencies and revealed by a brain intrinsic signal optical imaging system. These maps were compared before and during short-term elevation of IOP. The response amplitude of the orientation maps in area 17 decreased during a brief elevation of IOP. This decrease was dependent on the retinal perfusion pressure but not on the absolute IOP. The location of the most visible maps was spatial-frequency dependent. The blurring or loss of the pattern of the orientation maps was most severe when high-spatial-frequency gratings were used and appeared most significantly on the posterior part of the exposed cortex while IOP was elevated. However, the basic patterns of the maps remained unchanged. Changes in cortical signal were not due to changes in the optics of the eye with elevation of IOP. A stable normal IOP is essential for maintaining normal visual cortical functions. During a brief and high elevation of IOP, the cortical processing of high-spatial-frequency visual information was diminished because of a selectively functional decline of the retinogeniculocortical X pathway by a mechanism of retinal circulation origin.

Evaluation of a contact lens-embedded sensor for intraocular pressure measurement.

PubMed

Twa, Michael D; Roberts, Cynthia J; Karol, Huikai J; Mahmoud, Ashraf M; Weber, Paul A; Small, Robert H

2010-08-01

To evaluate a novel contact lens-embedded pressure sensor for continuous measurement of intraocular pressure (IOP). Repeated measurements of IOP and ocular pulse amplitude (OPA) were recorded in 12 eyes of 12 subjects in sitting and supine positions using 3 configurations of the dynamic contour tonometer: slit-lamp mounted (DCT), hand-held (HH), and contact lens-embedded sensor (CL). The IOP and OPA for each condition were compared using repeated measures ANOVA and the 95% limits of agreement were calculated. The sitting IOP (mean and 95% CI) for each configuration was DCT: 16.3 mm Hg (15.6 to 17.1 mm Hg), HH: 16.6 mm Hg (15.6 to 17.6 mm Hg), and CL: 15.7 mm Hg (15 to 16.3 mm Hg). The sitting OPA for each configuration was DCT: 2.4 mm Hg (2.1 to 2.6 mm Hg), HH: 2.4 mm Hg (2.1 to 2.7 mm Hg), and CL: 2.1 mm Hg (1.8 to 2.3 mm Hg). Supine IOP and OPA measurements with the CL and HH sensors were both greater than their corresponding sitting measurements, but were significantly less with the CL sensor than the HH sensor. The mean difference and 95% Limits of Agreement were smallest for the DCT and CL sensor comparisons (0.7+/-3.9 mm Hg) and widest for the CL and HH sensors (-1.9+/-7.25 mm Hg); these wider limits were attributed to greater HH measurement variability. The CL sensor was comparable to HH and DCT sensors with sitting subjects and is a viable method for measuring IOP and OPA. Supine measurements of IOP and OPA were greater than sitting conditions and were comparatively lower with the CL sensor. HH measurements were more variable than CL measurements and this influenced the Limits of Agreement for both sitting and supine conditions.

Effects of topical anaesthetics and repeated tonometry on intraocular pressure.

PubMed

Jóhannesson, Gauti; Hallberg, Per; Eklund, Anders; Behndig, Anders; Lindén, Christina

2014-03-01

To investigate the effects of repeated measurements of intraocular pressure (IOP) using Goldmann applanation tonometry (GAT) and applanation resonance tonometry (ART) to identify mechanisms contributing to the expected IOP reduction. A prospective, single-centre study with six healthy volunteers. Consecutive repeated series (six measurements/serie/method) were made alternately on both eyes for 1 hr with oxybuprocaine/fluorescein in the right eye and tetracaine in the left. The left eye was Pentacam(®) photographed before and repeatedly for 20 min after the IOP measurements. On a separate occasion, the same volunteers received the same amount of anaesthetic drops for 1 hr but without repeated IOP measurements. A significant IOP reduction occurred with both ART and GAT in the oxybuprocaine-treated eye, -4.4 mmHg and -3.8 mmHg, respectively and with ART in the tetracaine eye, -2.1 mmHg. There was a significant difference in IOP reduction between the oxybuprocaine and tetracaine eyes with ART. There was a significant drop in anterior chamber volume (ACV) immediately after the IOP measurements, -12.6 μl that returned to pretrial level after 2 min. After 1 hr of receiving anaesthetic eye drops (without IOP measurements), the IOP decreased significantly in the oxybuprocaine eye for both ART and GAT, -3.1 and -1.7 mmHg, respectively, but not in the tetracaine eye (p = 0.72). The IOP reduction cannot be explained solely by aqueous humor being pressed out of the anterior chamber. While significant IOP reduction occurred with both tetracaine and oxybuprocaine after repeated mechanical applanation, the IOP reduction was significantly greater with oxybuprocaine. © 2013 The Authors. Acta Ophthalmologica © 2013 Acta Ophthalmologica Scandinavica Foundation.

21 CFR 886.3600 - Intraocular lens.

Code of Federal Regulations, 2011 CFR

2011-04-01

... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Intraocular lens. 886.3600 Section 886.3600 Food... DEVICES OPHTHALMIC DEVICES Prosthetic Devices § 886.3600 Intraocular lens. (a) Identification. An intraocular lens is a device made of materials such as glass or plastic intended to be implanted to replace...

Intraocular Pressure, Blood Pressure, and Retinal Blood Flow Autoregulation: A Mathematical Model to Clarify Their Relationship and Clinical Relevance

PubMed Central

Guidoboni, Giovanna; Harris, Alon; Cassani, Simone; Arciero, Julia; Siesky, Brent; Amireskandari, Annahita; Tobe, Leslie; Egan, Patrick; Januleviciene, Ingrida; Park, Joshua

2014-01-01

Purpose. This study investigates the relationship between intraocular pressure (IOP) and retinal hemodynamics and predicts how arterial blood pressure (BP) and blood flow autoregulation (AR) influence this relationship. Methods. A mathematical model is developed to simulate blood flow in the central retinal vessels and retinal microvasculature as current flowing through a network of resistances and capacitances. Variable resistances describe active and passive diameter changes due to AR and IOP. The model is validated by using clinically measured values of retinal blood flow and velocity. The model simulations for six theoretical patients with high, normal, and low BP (HBP-, NBP-, LBP-) and functional or absent AR (-wAR, -woAR) are compared with clinical data. Results. The model predicts that NBPwAR and HBPwAR patients can regulate retinal blood flow (RBF) as IOP varies between 15 and 23 mm Hg and between 23 and 29 mm Hg, respectively, whereas LBPwAR patients do not adequately regulate blood flow if IOP is 15 mm Hg or higher. Hemodynamic alterations would be noticeable only if IOP changes occur outside of the regulating range, which, most importantly, depend on BP. The model predictions are consistent with clinical data for IOP reduction via surgery and medications and for cases of induced IOP elevation. Conclusions. The theoretical model results suggest that the ability of IOP to induce noticeable changes in retinal hemodynamics depends on the levels of BP and AR of the individual. These predictions might help to explain the inconsistencies found in the clinical literature concerning the relationship between IOP and retinal hemodynamics. PMID:24876284

Relationship between raised intraocular pressure and ischemia-modified albumin in serum and humor aqueous: a pilot study in rabbits.

PubMed

Taskiran Comez, Arzu; Cakir, Dilek Ulker; Tutunculer, Funda Kirtay; Gencer, Baran; Tufan, Hasan Ali

2014-01-01

We evaluated the relationship between increased intraocular pressure (IOP), ischemia-modified albumin levels in serum (IMA-s) and in humor aqueous (IMA-HA) in rabbits. Twenty-five albino New Zealand rabbits weighing between 2.0 and 2.8 kg were used in this pilot study. With permission from Canakkale Onsekiz Mart University Animal Ethics Committee, the IOP of both eyes of each rabbit were recorded with a Tonopen (Tono-Pen XL, Reichart Inc., Depew, NY, USA) after the application of topical proparacaine 0.5% HCl anesthesia. Blood (4 mL) was collected from the marginal ear vein and an intracameral injection of 2.3 mg/mL sodium hyaluronate and subconjunctival dexamethasone was given in the right eye. Anterior chamber aqueous fluid was obtained using a limbal approach with a 27 gauge needle from both eyes. The left eyes were used as controls. IOP was measured on the 1(st), 3(rd) and 10(th) day after the initial injection, with Tonopen, IMA-s levels and IMA-HA examined simultaneously. Before the injections, IOP was 11.4±3.0 mm Hg in the right eye and 11.3±3.1 mm Hg in the left eye (P>0.05). There was a statistically significant difference between IMA-s levels before the IOP increase (IMA-s0) and IMA-s levels on the 1(st) and 3(rd) days after the increase in IOP (P=0.012 and P=0.01, respectively). No difference was observed between IMA-s0 and serum IMA levels on the 10(th) day (IMA-s10) after IOP increase (P=0.989). IMA-HA in the right eye in the first day after the injection was positively correlated with IOP (r=0.748; P=0.02). No other correlation is found between any other parameter with IMA-HA levels at any test time. A statistically significant positive correlation was observed between IMA-s values and IOP on the 1(st) and 3(rd) days (r=0.398, P=0.04 and r=0.382, P=0.04, respectively). There was no correlation between IMA-s levels and increased IOP on the 10(th) day after IOP increase (r=0.026, P=0.902). IMA may be an important indicator of acute damage caused by

Optical eye tracking system for real-time noninvasive tumor localization in external beam radiotherapy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Via, Riccardo, E-mail: riccardo.via@polimi.it; Fassi, Aurora; Fattori, Giovanni

Purpose: External beam radiotherapy currently represents an important therapeutic strategy for the treatment of intraocular tumors. Accurate target localization and efficient compensation of involuntary eye movements are crucial to avoid deviations in dose distribution with respect to the treatment plan. This paper describes an eye tracking system (ETS) based on noninvasive infrared video imaging. The system was designed for capturing the tridimensional (3D) ocular motion and provides an on-line estimation of intraocular lesions position based on a priori knowledge coming from volumetric imaging. Methods: Eye tracking is performed by localizing cornea and pupil centers on stereo images captured by twomore » calibrated video cameras, exploiting eye reflections produced by infrared illumination. Additionally, torsional eye movements are detected by template matching in the iris region of eye images. This information allows estimating the 3D position and orientation of the eye by means of an eye local reference system. By combining ETS measurements with volumetric imaging for treatment planning [computed tomography (CT) and magnetic resonance (MR)], one is able to map the position of the lesion to be treated in local eye coordinates, thus enabling real-time tumor referencing during treatment setup and irradiation. Experimental tests on an eye phantom and seven healthy subjects were performed to assess ETS tracking accuracy. Results: Measurements on phantom showed an overall median accuracy within 0.16 mm and 0.40° for translations and rotations, respectively. Torsional movements were affected by 0.28° median uncertainty. On healthy subjects, the gaze direction error ranged between 0.19° and 0.82° at a median working distance of 29 cm. The median processing time of the eye tracking algorithm was 18.60 ms, thus allowing eye monitoring up to 50 Hz. Conclusions: A noninvasive ETS prototype was designed to perform real-time target localization and eye movement

In vitro oxygen sensing using intraocular microrobots.

PubMed

Ergeneman, Olgaç; Chatzipirpiridis, George; Pokki, Juho; Marín-Suárez, Marta; Sotiriou, Georgios A; Medina-Rodríguez, Santiago; Sánchez, Jorge F Fernández; Fernández-Gutiérrez, Alberto; Pané, Salvador; Nelson, Bradley J

2012-11-01

We present a luminescence oxygen sensor integrated with a wireless intraocular microrobot for minimally-invasive diagnosis. This microrobot can be accurately controlled in the intraocular cavity by applying magnetic fields. The microrobot consists of a magnetic body susceptible to magnetic fields and a sensor coating. This coating embodies Pt(II) octaethylporphine (PtOEP) dyes as the luminescence material and polystyrene as a supporting matrix, and it can be wirelessly excited and read out by optical means. The sensor works based on quenching of luminescence in the presence of oxygen. The excitation and emission spectrum, response time, and oxygen sensitivity of the sensor were characterized using a spectrometer. A custom device was designed and built to use this sensor for intraocular measurements with the microrobot. Due to the intrinsic nature of luminescence lifetimes, a frequency-domain lifetime measurement approach was used. An alternative sensor design with increased performance was demonstrated by using poly(styrene-co-maleic anhydride) (PS-MA) and PtOEP nanospheres.

Effect of optical aberrations on intraocular pressure measurements using a microscale optical implant in ex vivo rabbit eyes

NASA Astrophysics Data System (ADS)

Han, Samuel J.; Park, Haeri; Lee, Jeong Oen; Choo, Hyuck

2018-04-01

Elevated intraocular pressure (IOP) is the only modifiable major risk factor of glaucoma. Recently, accurate and continuous IOP monitoring has been demonstrated in vivo using an implantable sensor based on optical resonance with remote optical readout to improve patient outcomes. Here, we investigate the relationship between optical aberrations of ex vivo rabbit eyes and the performance of the IOP sensor using a custom-built setup integrated with a Shack-Hartmann sensor. The sensor readouts became less accurate as the aberrations increased in magnitude, but they remained within the clinically acceptable range. For root-mean-square wavefront errors of 0.10 to 0.94 μm, the accuracy and the signal-to-noise ratio were 0.58 ± 0.32 mm Hg and 15.57 ± 4.85 dB, respectively.

Assessment of intraocular pressure measured by Reichert Ocular Response Analyzer, Goldmann Applanation Tonometry, and Dynamic Contour Tonometry in healthy individuals

PubMed Central

Ouyang, Ping-Bo; Li, Cong-Yi; Zhu, Xiao-Hua; Duan, Xuan-Chu

2012-01-01

AIM To investigate the accuracy of intraocular pressure (IOP) as measured by a Reichert Ocular Response Analyzer (ORA), as well as the relationship between central corneal thickness (CCT) and IOP as measured by ORA, Goldmann applanation tonometry (GAT), and dynamic contour tonometry (DCT). METHODS A total of 158 healthy individuals (296 eyes) were chosen randomly for measurement of IOP. After CCT was measured using A-ultrasound (A-US), IOP was measured by ORA, GAT, and DCT devices in a randomized order. The IOP values acquired using each of the three tonometries were compared, and the relationship between CCT and IOP values were analyzed separately. Two IOP values, Goldmann-correlated IOP value (IOPg) and corneal-compensated intraocular pressure (IOPcc), were got using ORA. Three groups were defined according to CCT: 1) thin cornea (CCT<520µm); 2) normal-thickness cornea (CCT: 520–580µm); and 3) thick cornea (CCT>580µm) groups. RESULTS In normal subjects, IOP measurements were 14.95±2.99mmHg with ORA (IOPg), 15.21±2.77mmHg with ORA (IOPcc), 15.22±2.77mmHg with GAT, and 15.49±2.56mmHg with DCT. Mean differences were 0.01±2.29mmHg between IOPcc and GAT (P>0.05) and 0.28±2.20mmHg between IOPcc and DCT (P>0.05). There was a greater correlation between IOPcc and DCT (r=0.946, P=0.000) than that between IOPcc and GAT (r=0.845, P=0.000). DCT had a significant correlation with GAT (r=0.854, P=0.000). GAT was moderately correlated with CCT (r=0.296, P<0.001), while IOPcc showed a weak but significant correlation with CCT (r=−0.155, P=0.007). There was a strong negative correlation between CCT and the difference between IOPcc and GAT(r=-0.803, P=0.000), with every 10µm increase in CCT resulting in an increase in this difference of 0.35mmHg. The thick cornea group (CCT>580µm) showed the least significant correlation between IOPcc and GAT (r=0.859, P=0.000); while the thin cornea group (CCT<520µm) had the most significant correlation between IOPcc and GAT (r=0

Stress Analysis and Fatigue Behaviour of PTFE-Bronze Layered Journal Bearing under Real-Time Dynamic Loading

NASA Astrophysics Data System (ADS)

Duman, M. S.; Kaplan, E.; Cuvalcı, O.

2018-01-01

The present paper is based on experimental studies and numerical simulations on the surface fatigue failure of the PTFE-bronze layered journal bearings under real-time loading. ‘Permaglide Plain Bearings P10’ type journal bearings were experimentally tested under different real time dynamic loadings by using real time journal bearing test system in our laboratory. The journal bearing consists of a PTFE-bronze layer approximately 0.32 mm thick on the steel support layer with 2.18 mm thick. Two different approaches have been considered with in experiments: (i) under real- time constant loading with varying bearing widths, (ii) under different real-time loadings at constant bearing widths. Fatigue regions, micro-crack dispersion and stress distributions occurred at the journal bearing were experimentally and theoretically investigated. The relation between fatigue region and pressure distributions were investigated by determining the circumferential pressure distribution under real-time dynamic loadings for the position of every 10° crank angles. In the theoretical part; stress and deformation distributions at the surface of the journal bearing analysed by using finite element methods to determine the relationship between stress and fatigue behaviour. As a result of this study, the maximum oil pressure and fatigue cracks were observed in the most heavily loaded regions of the bearing surface. Experimental results show that PTFE-Bronze layered journal bearings fatigue behaviour is better than the bearings include white metal alloy.

The Effect of a Diving Mask on Intraocular Pressure in a Healthy Population.

PubMed

Goenadi, Catherina Josephine; Law, David Zhiwei; Lee, Jia Wen; Ong, Ee Lin; Chee, Wai Kitt; Cheng, Jason

2016-01-01

Swimming goggles increase the intraocular pressure (IOP) via the periorbital frame pressure and suction effect. In comparison, diving masks have a larger frame rim and incorporate the nose. The exact effect(s) of diving masks on IOP is unknown. This study evaluates the influence of diving masks on IOP in normal, healthy subjects. Tonometry was performed in both eyes of all subjects with an AVIA(®)Tono-Pen by a single investigator. Measurements were taken at baseline without the diving mask and with the subjects wearing a small-volume, double-window diving mask, but with the mask lenses removed. Two IOP readings in each eye were measured, and an additional reading was measured if the difference between the initial 2 was ≥2 mm Hg. Central corneal thickness (CCT) was also measured in each eye, using a contact pachymeter (OcuScan(®)Alcon). Forty eyes of 20 healthy volunteers (age 29.7 ± 9.3 years; range 21-52) were included. The mean CCT was 544.4 ± 43.5 µm. The mean IOP before the diving mask was worn had been 17.23 ± 2.18 mm Hg (n = 40). The IOP decreased by 0.43 mm Hg (p $1003c; 0.05) to 16.80 ± 2.57 mm Hg after the diving mask had been put on. There was no correlation between IOP change and age (r = 0.143, p = 0.337), gender (r = -0.174, p = 0.283) or CCT (r = -0.123, p = 0.445). There was no increase in IOP after the diving mask had been worn. A small but statistically significant decrease in IOP was observed. This study demonstrates that unlike swimming goggles, the strap tension and frame pressure on the periorbital tissue from a diving mask does not increase IOP. Diving masks may be a suitable alternative to swimming goggles for patients with advanced glaucoma or glaucoma filtration surgery.

The Effect of a Diving Mask on Intraocular Pressure in a Healthy Population

PubMed Central

Goenadi, Catherina Josephine; Law, David Zhiwei; Lee, Jia Wen; Ong, Ee Lin; Chee, Wai Kitt; Cheng, Jason

2016-01-01

Purpose Swimming goggles increase the intraocular pressure (IOP) via the periorbital frame pressure and suction effect. In comparison, diving masks have a larger frame rim and incorporate the nose. The exact effect(s) of diving masks on IOP is unknown. This study evaluates the influence of diving masks on IOP in normal, healthy subjects. Methods Tonometry was performed in both eyes of all subjects with an AVIA®Tono-Pen by a single investigator. Measurements were taken at baseline without the diving mask and with the subjects wearing a small-volume, double-window diving mask, but with the mask lenses removed. Two IOP readings in each eye were measured, and an additional reading was measured if the difference between the initial 2 was ≥2 mm Hg. Central corneal thickness (CCT) was also measured in each eye, using a contact pachymeter (OcuScan®Alcon). Results Forty eyes of 20 healthy volunteers (age 29.7 ± 9.3 years; range 21–52) were included. The mean CCT was 544.4 ± 43.5 µm. The mean IOP before the diving mask was worn had been 17.23 ± 2.18 mm Hg (n = 40). The IOP decreased by 0.43 mm Hg (p $1003c; 0.05) to 16.80 ± 2.57 mm Hg after the diving mask had been put on. There was no correlation between IOP change and age (r = 0.143, p = 0.337), gender (r = −0.174, p = 0.283) or CCT (r = −0.123, p = 0.445). Conclusion There was no increase in IOP after the diving mask had been worn. A small but statistically significant decrease in IOP was observed. This study demonstrates that unlike swimming goggles, the strap tension and frame pressure on the periorbital tissue from a diving mask does not increase IOP. Diving masks may be a suitable alternative to swimming goggles for patients with advanced glaucoma or glaucoma filtration surgery. PMID:27462262

The Real-Time Wall Interference Correction System of the NASA Ames 12-Foot Pressure Wind Tunnel

NASA Technical Reports Server (NTRS)

Ulbrich, Norbert

1998-01-01

An improved version of the Wall Signature Method was developed to compute wall interference effects in three-dimensional subsonic wind tunnel testing of aircraft models in real-time. The method may be applied to a full-span or a semispan model. A simplified singularity representation of the aircraft model is used. Fuselage, support system, propulsion simulator, and separation wake volume blockage effects are represented by point sources and sinks. Lifting effects are represented by semi-infinite line doublets. The singularity representation of the test article is combined with the measurement of wind tunnel test reference conditions, wall pressure, lift force, thrust force, pitching moment, rolling moment, and pre-computed solutions of the subsonic potential equation to determine first order wall interference corrections. Second order wall interference corrections for pitching and rolling moment coefficient are also determined. A new procedure is presented that estimates a rolling moment coefficient correction for wings with non-symmetric lift distribution. Experimental data obtained during the calibration of the Ames Bipod model support system and during tests of two semispan models mounted on an image plane in the NASA Ames 12 ft. Pressure Wind Tunnel are used to demonstrate the application of the wall interference correction method.

Real-time Kp predictions from ACE real time solar wind

NASA Astrophysics Data System (ADS)

Detman, Thomas; Joselyn, Joann

1999-06-01

The Advanced Composition Explorer (ACE) spacecraft provides nearly continuous monitoring of solar wind plasma, magnetic fields, and energetic particles from the Sun-Earth L1 Lagrange point upstream of Earth in the solar wind. The Space Environment Center (SEC) in Boulder receives ACE telemetry from a group of international network of tracking stations. One-minute, and 1-hour averages of solar wind speed, density, temperature, and magnetic field components are posted on SEC's World Wide Web page within 3 to 5 minutes after they are measured. The ACE Real Time Solar Wind (RTSW) can be used to provide real-time warnings and short term forecasts of geomagnetic storms based on the (traditional) Kp index. Here, we use historical data to evaluate the performance of the first real-time Kp prediction algorithm to become operational.

Advanced pigment dispersion glaucoma secondary to phakic intraocular collamer lens implant.

PubMed

Ye, Clara; Patel, Cajal K; Momont, Anna C; Liu, Yao

2018-06-01

We report a case of pigment dispersion glaucoma secondary to uncomplicated phakic intraocular collamer lens (ICL) (Visian ICL™, Staar Inc., Monrovia, CA) implant that resulted in advanced visual field loss. A 50-year-old man presented for routine follow-up status post bilateral phakic intraocular collamer lens (ICL) placement 8 years earlier. He was incidentally found to have a decline in visual acuity from an anterior subcapsular cataract and elevated intraocular pressure (IOP) in the left eye. There were signs of pigment dispersion and no evidence of angle closure. Diffuse optic nerve thinning was consistent with advanced glaucomatous visual field defects. Pigment dispersion was also present in the patient's right eye, but without elevated IOP or visual field defects. The patient was treated with topical glaucoma medications and the phakic ICL in the left eye was removed concurrently with cataract surgery to prevent further visual field loss. Pigment dispersion glaucoma is a serious adverse outcome after phakic ICL implantation and regular post-operative monitoring may prevent advanced visual field loss.

Portable Dew Point Mass Spectrometry System for Real-Time Gas and Moisture Analysis

NASA Technical Reports Server (NTRS)

Arkin, C.; Gillespie, Stacey; Ratzel, Christopher

2010-01-01

A portable instrument incorporates both mass spectrometry and dew point measurement to provide real-time, quantitative gas measurements of helium, nitrogen, oxygen, argon, and carbon dioxide, along with real-time, quantitative moisture analysis. The Portable Dew Point Mass Spectrometry (PDP-MS) system comprises a single quadrupole mass spectrometer and a high vacuum system consisting of a turbopump and a diaphragm-backing pump. A capacitive membrane dew point sensor was placed upstream of the MS, but still within the pressure-flow control pneumatic region. Pressure-flow control was achieved with an upstream precision metering valve, a capacitance diaphragm gauge, and a downstream mass flow controller. User configurable LabVIEW software was developed to provide real-time concentration data for the MS, dew point monitor, and sample delivery system pressure control, pressure and flow monitoring, and recording. The system has been designed to include in situ, NIST-traceable calibration. Certain sample tubing retains sufficient water that even if the sample is dry, the sample tube will desorb water to an amount resulting in moisture concentration errors up to 500 ppm for as long as 10 minutes. It was determined that Bev-A-Line IV was the best sample line to use. As a result of this issue, it is prudent to add a high-level humidity sensor to PDP-MS so such events can be prevented in the future.

Effect of sub-Tenon's and peribulbar anesthesia on intraocular pressure and ocular pulse amplitude.

PubMed

Pianka, P; Weintraub-Padova, H; Lazar, M; Geyer, O

2001-08-01

To compare the effect of peribulbar and sub-Tenon's anesthesia on intraocular pressure (IOP) and ocular pulse amplitude (OPA) in the injected eye and the fellow noninjected (control) eye. Tel Aviv Medical Center, Tel Aviv, Israel. This prospective study measured IOP and OPA at baseline and 1 and 10 minutes after administration of lidocaine anesthesia in 40 consecutive adult patients having elective cataract surgery. The IOP remained stable throughout the study with both modes of anesthesia. One minute after injection of the anesthetic agent, the OPA was significantly decreased in the injected eyes in both the sub-Tenon's (24%; P < .05) and peribulbar (25%; P < .05) groups. The decrease in the OPA in the sub-Tenon's group (14%; P < .05) was detectable after 10 minutes in the control eyes. In the peribulbar anesthesia group, the OPA in the control eyes increased significantly (9%; P < .05) 1 minute after injection of the anesthetic agent, returning to preinjection levels 10 minutes after the injection. The OPA in the eyes in which lidocaine was injected decreased significantly in both the sub-Tenon's and peribulbar groups. These findings have implications for the management of patients whose ocular circulation may be compromised.

Time pressure in scenario-based online construction safety quizzes and its effect on students' performance

NASA Astrophysics Data System (ADS)

Jaeger, Martin; Adair, Desmond

2017-05-01

Online quizzes have been shown to be effective learning and assessment approaches. However, if scenario-based online construction safety quizzes do not include time pressure similar to real-world situations, they reflect situations too ideally. The purpose of this paper is to compare engineering students' performance when carrying out an online construction safety quiz with time pressure versus an online construction safety quiz without time pressure. Two versions of an online construction safety quiz are developed and administered to randomly assigned engineering students based on a quasi-experimental post-test design. The findings contribute to scenario-based learning and assessment of construction safety in four ways. First, the results confirm earlier findings that 'intrinsic stress' does not seem to impair students' performance. Second, students who carry out the online construction safety quiz with time pressure are less likely to 'learn by trial and error'. Third, students exposed to time pressure appreciate that they become better prepared for real life. Finally, preparing students to work under time pressure is an important industry requirement. The results of this study should encourage engineering educators to explore and implement ways to include time pressure in scenario-based online quizzes and learning.

Real-Time Processing of Pressure-Sensitive Paint Images

DTIC Science & Technology

2006-12-01

intermediate or final data to the hard disk in 3D grid format. In addition to the pressure or pressure coefficient at every grid point, the saved file may...occurs. Nevertheless, to achieve an accurate mapping between 2D image coordinates and 3D spatial coordinates, additional parameters must be introduced. A...improved mapping between the 2D and 3D coordinates. In a more sophisticated approach, additional terms corresponding to specific deformation modes

Air Bubble-Induced High Intraocular Pressure After Descemet Membrane Endothelial Keratoplasty.

PubMed

Röck, Daniel; Bartz-Schmidt, Karl Ulrich; Röck, Tobias; Yoeruek, Efdal

2016-08-01

To investigate the incidence and risk factors of pupillary block caused by an air bubble in the anterior chamber in the early postoperative period after Descemet membrane endothelial keratoplasty (DMEK). A retrospective review was conducted in 306 eyes that underwent DMEK from September 2009 through October 2014 at the Tübingen Eye Hospital. Intraocular pressure (IOP) elevation was defined as a spike above 30 mm Hg. In the first 190 eyes, an intraoperative peripheral iridectomy was performed at the 12-o'clock position and in the other 116 eyes at the 6-o'clock position. If possible, reasons for IOP elevation were identified. For all eyes, preoperative and postoperative slit-lamp examinations and IOP measurements were performed. Overall, 30 eyes (9.8%) showed a postoperative IOP elevation within the first postoperative day. The incidence of IOP elevation was 13.9% (5/36) in the triple DMEK group, and 2 of 5 phakic eyes (40%) developed an air bubble-induced IOP elevation. All eyes presented with a de novo IOP elevation, associated in 25 patients with pupillary block from air anterior to iris and in 5 patients with angle closure from air migration posterior to the iris. All of them had an iridectomy at the 12-o'clock position. A postoperative pupillary block with IOP elevation caused by the residual intraoperative air bubble may be an important complication that could be avoided by close and frequent observations, especially in the first postoperative hours and by an inferior peripheral iridectomy and an air bubble with a volume of ≤80% of the anterior chamber.

The Risk of Intraocular Pressure Elevation in Pediatric Non-infectious Uveitis

PubMed Central

Kothari, Srishti; Foster, C. Stephen; Pistilli, Maxwell; Liesegang, Teresa L.; Daniel, Ebenezer; Sen, H. Nida; Suhler, Eric B.; Thorne, Jennifer E.; Jabs, Douglas A.; Levy-Clarke, Grace A.; Nussenblatt, Robert B.; Rosenbaum, James T.; Lawrence, Scott D.; Kempen, John H.

2015-01-01

Purpose To characterize the risk and risk factors for intraocular pressure (IOP) elevation in pediatric non-infectious uveitis. Design Multi-center retrospective cohort study. Participants Nine hundred sixteen children (1593 eyes) <18 years old at presentation with non-infectious uveitis followed between January 1978 through December 2007 at five academic uveitis centers in United States. Methods Medical records review by trained, certified experts. Main outcome measures Prevalence and incidence of IOP≥21 and ≥30mmHg and incidence of a rise in IOP by ≥10mmHg. To avoid under ascertainment, outcomes were counted as present when IOP-lowering therapies were in use. Results Initially 251 (15.8%) and 46 eyes (2.9%) had IOP≥21 and ≥30mmHg, respectively. Factors associated with presenting IOP elevation included age 6–12 years (versus other pediatric ages), prior cataract surgery (adjusted odds ratio≥21mmHg [aOR21]=2.42, P=0.01), pars plana vitrectomy (adjusted odds ratio≥30mmHg[aOR30]=11.1, P=0.03), duration of uveitis ≥6 months (aORs30 up to 11.8, P<0.001), contralateral IOP elevation (aOR21=16.9, aOR30=8.29; each P<0.001), visual acuity worse than 20/40 (aORs21 up to 1.73, P=0.02; aORs30 up to 2.81 P=0.03), and topical corticosteroid use (aORs up to 8.92, P<0.001 in a dose-response relationship). The median follow-up was 1.25 years (interquartile range 0.4–3.66). The estimated risk of any observed IOP elevation to ≥21 mmHg, ≥30 mmHg and of a rise in IOP by ≥10mmHg was 33.4%, 14.8% and 24.4% respectively within 2 years. Factors associated with IOP elevation included pars plana vitrectomy (adjusted hazard ratio≥21mmHg[aHR21]=3.36, P<0.001), contralateral IOP elevation (aHRs up to 9.54, P<0.001), the use of topical (aHRs up to 8.77 that followed a dose-response relationship, P<0.001), periocular (aHRs up to 7.96, P<0.001) and intraocular (aHRs up to 19.7, P<0.001) corticosteroids. Conclusions IOP elevation affects a large minority of children

Changes in blood pressure and sleep duration in patients with blue light-blocking/yellow-tinted intraocular lens (CHUKYO study).

PubMed

Ichikawa, Kazuo

2014-07-01

Blood pressure and sleep duration may be influenced by retinal light exposure. Cataracts may exert such an influence by decreasing the transparency of the crystalline lens. A large-scale clinical study was conducted to examine changes in blood pressure and sleep duration after intraocular lens (IOL) implantation during cataract surgery and to investigate how different types of IOL influence the degree of these effects. Using a questionnaire, we collected information, including blood pressure measurement and sleep duration, from 1367 patients (1367 eyes) before IOL implantation, 1 week after IOL implantation and 1 month after IOL implantation. Systolic and diastolic blood pressures were significantly decreased in the total patient group after implantation. The decrease in systolic blood pressure 1 month after implantation was significantly more in patients who received a yellow-tinted IOL than it was in those who received an ultraviolet (UV) light-filtering IOL. The post-implantation sleep duration, including naps, became shorter in patients who had slept too much and became longer in those who had slept too little before IOL implantation. Our observations suggest that a yellow-tinted IOL is better for patients with high blood pressure than a UV light-filtering IOL. Furthermore, the yellow-tinted IOL is as good as the UV light-filtering IOL for improving sleep duration. A pale yellow-tinted IOL is likely to be superior to a moderate yellow-tinted IOL in terms of allowing patients to discriminate different colors. Thus, the pale yellow-tinted IOL appears to be better for patients than the UV light-filtering IOL and the moderate yellow-tinted IOL.

A modified elastance model to control mock ventricles in real-time: numerical and experimental validation.

PubMed

Colacino, Francesco Maria; Moscato, Francesco; Piedimonte, Fabio; Danieli, Guido; Nicosia, Salvatore; Arabia, Maurizio

2008-01-01

This article describes an elastance-based mock ventricle able to reproduce the correct ventricular pressure-volume relationship and its correct interaction with the hydraulic circuit connected to it. A real-time control of the mock ventricle was obtained by a new left ventricular mathematical model including resistive and inductive terms added to the classical Suga-Sagawa elastance model throughout the whole cardiac cycle. A valved piston pump was used to mimic the left ventricle. The pressure measured into the pump chamber was fed back into the mathematical model and the calculated reference left ventricular volume was used to drive the piston. Results show that the classical model is very sensitive to pressure disturbances, especially during the filling phase, while the modified model is able to filter out the oscillations thus eliminating their detrimental effects. The presented model is thus suitable to control mock ventricles in real-time, where sudden pressure disturbances represent a key issue and are not negligible. This real-time controlled mock ventricle is able to reproduce the elastance mechanism of a natural ventricle by mimicking its preload (mean atrial pressure) and afterload (mean aortic pressure) sensitivity, i.e., the Starling law. Therefore, it can be used for designing and testing cardiovascular prostheses due to its capability to reproduce the correct ventricle-vascular system interaction.

[New trends of customizing intraocular lens choice].

PubMed

He, Shou-zhi

2006-05-01

Definition and basic principle of customizing intraocular lens choice are described. The importance of the choicing intraocular lens for individual patient is illustrated. The review emphasizes that it is surgeon's responsibility to choice the appropriate intraocular lens for the best postoperative outcome and patient's satisfaction.

Oral Omega-3 Supplementation Lowers Intraocular Pressure in Normotensive Adults.

PubMed

Downie, Laura Elizabeth; Vingrys, Algis Jonas

2018-05-01

Elevated intraocular pressure (IOP) is the major modifiable risk factor for the sight-threatening eye disease, glaucoma. We investigated whether oral omega-3 supplements affect IOP in normotensive adults. We undertook a pooled analysis of data from two double-masked, placebo-controlled randomized trials (Australian New Zealand Clinical Trials Registry, ACTRN12614001019695, ACTRN12615000173594) that investigated the efficacy and safety of oral omega-3 supplementation for treating ocular surface inflammation. Recruitment involved adults ( n = 105) with IOP <21 mm Hg, and without a current or prior glaucoma diagnosis. Participants were randomly allocated to either an oral omega-3 (∼1000 mg/day eicosapentaenoic acid + ∼500 mg/day docosahexaenoic acid ± 900 mg/day α-linolenic acid) or placebo (olive oil, 1500 mg/day) supplement. IOP was quantified at baseline and after 3 months of supplementation (day 90). Change in IOP, relative to baseline, was compared between groups. At baseline, participants were of similar age (omega-3/placebo groups: mean ± SEM, 33.7 ± 1.7, n = 72/35.6 ± 3.0 years, n = 33), sex (65%/79% female), and had similar IOP (14.3 ± 0.3/13.8 ± 0.5 mm Hg). At day 90, IOP was reduced to 13.6 ± 0.3 mm Hg in the omega-3 group; controls had a slight IOP increase to 14.2 ± 0.4 mm Hg ( P < 0.05). Oral omega-3 supplementation for 3 months significantly reduced IOP in normotensive adults. To our knowledge, this is the first study to report that omega-3 fatty acids lower IOP in humans. These findings justify further investigation into the therapeutic potential of omega-3 supplementation for reducing IOP, to prevent and/or treat conditions with IOP elevation, including ocular hypertension and glaucoma.

Modeling and Real-Time Process Monitoring of Organometallic Chemical Vapor Deposition of III-V Phosphides and Nitrides at Low and High Pressure

NASA Technical Reports Server (NTRS)

Bachmann, K. J.; Cardelino, B. H.; Moore, C. E.; Cardelino, C. A.; Sukidi, N.; McCall, S.

1999-01-01

The purpose of this paper is to review modeling and real-time monitoring by robust methods of reflectance spectroscopy of organometallic chemical vapor deposition (OMCVD) processes in extreme regimes of pressure. The merits of p-polarized reflectance spectroscopy under the conditions of chemical beam epitaxy (CBE) and of internal transmission spectroscopy and principal angle spectroscopy at high pressure are assessed. In order to extend OMCVD to materials that exhibit large thermal decomposition pressure at their optimum growth temperature we have designed and built a differentially-pressure-controlled (DCP) OMCVD reactor for use at pressures greater than or equal to 6 atm. We also describe a compact hard-shell (CHS) reactor for extending the pressure range to 100 atm. At such very high pressure the decomposition of source vapors occurs in the vapor phase, and is coupled to flow dynamics and transport. Rate constants for homogeneous gas phase reactions can be predicted based on a combination of first principles and semi-empirical calculations. The pressure dependence of unimolecular rate constants is described by RRKM theory, but requires variational and anharmonicity corrections not included in presently available calculations with the exception of ammonia decomposition. Commercial codes that include chemical reactions and transport exist, but do not adequately cover at present the kinetics of heteroepitaxial crystal growth.

Intraocular pressure, blood pressure, and retinal blood flow autoregulation: a mathematical model to clarify their relationship and clinical relevance.

PubMed

Guidoboni, Giovanna; Harris, Alon; Cassani, Simone; Arciero, Julia; Siesky, Brent; Amireskandari, Annahita; Tobe, Leslie; Egan, Patrick; Januleviciene, Ingrida; Park, Joshua

2014-05-29

This study investigates the relationship between intraocular pressure (IOP) and retinal hemodynamics and predicts how arterial blood pressure (BP) and blood flow autoregulation (AR) influence this relationship. A mathematical model is developed to simulate blood flow in the central retinal vessels and retinal microvasculature as current flowing through a network of resistances and capacitances. Variable resistances describe active and passive diameter changes due to AR and IOP. The model is validated by using clinically measured values of retinal blood flow and velocity. The model simulations for six theoretical patients with high, normal, and low BP (HBP-, NBP-, LBP-) and functional or absent AR (-wAR, -woAR) are compared with clinical data. The model predicts that NBPwAR and HBPwAR patients can regulate retinal blood flow (RBF) as IOP varies between 15 and 23 mm Hg and between 23 and 29 mm Hg, respectively, whereas LBPwAR patients do not adequately regulate blood flow if IOP is 15 mm Hg or higher. Hemodynamic alterations would be noticeable only if IOP changes occur outside of the regulating range, which, most importantly, depend on BP. The model predictions are consistent with clinical data for IOP reduction via surgery and medications and for cases of induced IOP elevation. The theoretical model results suggest that the ability of IOP to induce noticeable changes in retinal hemodynamics depends on the levels of BP and AR of the individual. These predictions might help to explain the inconsistencies found in the clinical literature concerning the relationship between IOP and retinal hemodynamics. Copyright 2014 The Association for Research in Vision and Ophthalmology, Inc.

Relationship between progression of visual field defect and intraocular pressure in primary open-angle glaucoma.

PubMed

Naito, Tomoko; Yoshikawa, Keiji; Mizoue, Shiro; Nanno, Mami; Kimura, Tairo; Suzumura, Hirotaka; Shiraga, Fumio

2015-01-01

To analyze the relationship between intraocular pressure (IOP) and the progression of visual field defects in Japanese primary open-angle glaucoma (POAG) and normal-tension glaucoma (NTG) patients. The subjects of the study were patients undergoing treatment for POAG or NTG who had performed visual field tests at least ten times with a Humphrey field analyzer (Swedish interactive thresholding algorithm standard, C30-2 program). The progression of visual field defects was defined by a significantly negative value of the mean deviation slope at the final visual field test during the follow-up period. The relationships between the progression of visual field defects and IOP, as well as other clinical factors, were retrospectively analyzed. A total of 156 eyes of 156 patients were included in the analysis. Significant progression of visual field defects was observed in 70 eyes of 70 patients (44.9%), while no significant progression was evident in 86 eyes of 86 patients (55.1%). The eyes with visual field defect progression had significantly lower baseline IOP (P<0.05), as well as significantly lower IOP reduction rate (P<0.01). The standard deviation of IOP values during follow-up was significantly greater in the eyes with visual field defect progression than in eyes without (P<0.05). Reducing IOP is thought to be useful for Japanese POAG or NTG patients to suppress the progression of visual field defects. In NTG, IOP management should take into account not only achieving the target IOP, but also minimizing the fluctuation of IOP during follow-up period.

Intraocular (Eye) Melanoma—Patient Version

Cancer.gov

Intraocular (uveal) melanoma is a rare cancer that forms in the eye. It usually has no early signs or symptoms. As with melanoma of the skin, risk factors include having fair skin and light-colored eyes. Start here to find information on intraocular melanoma treatment.

SOFTWARE DESIGN FOR REAL-TIME SYSTEMS.

DTIC Science & Technology

Real-time computer systems and real-time computations are defined for the purposes of this report. The design of software for real - time systems is...discussed, employing the concept that all real - time systems belong to one of two types. The types are classified according to the type of control...program used; namely: Pre-assigned Iterative Cycle and Real-time Queueing. The two types of real - time systems are described in general, with supplemental

Real-Time Earthquake Analysis for Disaster Mitigation (READI) Network

NASA Astrophysics Data System (ADS)

Bock, Y.

2014-12-01

Real-time GNSS networks are making a significant impact on our ability to forecast, assess, and mitigate the effects of geological hazards. I describe the activities of the Real-time Earthquake Analysis for Disaster Mitigation (READI) working group. The group leverages 600+ real-time GPS stations in western North America operated by UNAVCO (PBO network), Central Washington University (PANGA), US Geological Survey & Scripps Institution of Oceanography (SCIGN project), UC Berkeley & US Geological Survey (BARD network), and the Pacific Geosciences Centre (WCDA project). Our goal is to demonstrate an earthquake and tsunami early warning system for western North America. Rapid response is particularly important for those coastal communities that are in the near-source region of large earthquakes and may have only minutes of warning time, and who today are not adequately covered by existing seismic and basin-wide ocean-buoy monitoring systems. The READI working group is performing comparisons of independent real time analyses of 1 Hz GPS data for station displacements and is participating in government-sponsored earthquake and tsunami exercises in the Western U.S. I describe a prototype seismogeodetic system using a cluster of southern California stations that includes GNSS tracking and collocation with MEMS accelerometers for real-time estimation of seismic velocity and displacement waveforms, which has advantages for improved earthquake early warning and tsunami forecasts compared to seismic-only or GPS-only methods. The READI working group's ultimate goal is to participate in an Indo-Pacific Tsunami early warning system that utilizes GNSS real-time displacements and ionospheric measurements along with seismic, near-shore buoys and ocean-bottom pressure sensors, where available, to rapidly estimate magnitude and finite fault slip models for large earthquakes, and then forecast tsunami source, energy scale, geographic extent, inundation and runup. This will require

Intraocular methotrexate can induce extended remission in some patients in noninfectious uveitis.

PubMed

Taylor, Simon R J; Banker, Alay; Schlaen, Ariel; Couto, Cristobal; Matthe, Egbert; Joshi, Lavnish; Menezo, Victor; Nguyen, Ethan; Tomkins-Netzer, Oren; Bar, Asaf; Morarji, Jiten; McCluskey, Peter; Lightman, Sue

2013-01-01

To assess the outcomes of the intravitreal administration of methotrexate in uveitis. Multicenter, retrospective interventional case series of patients with noninfectious uveitis. Thirty-eight eyes of 30 patients were enrolled, including a total of 54 intravitreal injections of methotrexate at a dose of 400 µg in 0.1 mL. The primary outcome measure was visual acuity. Secondary outcome measures included control of intraocular inflammation and cystoid macular edema, time to relapse, development of adverse events, and levels of systemic corticosteroid and immunosuppressive therapy. Methotrexate proved effective in controlling intraocular inflammation and improving vision in 30 of 38 eyes (79%). The side effect profile was good, with no reported serious ocular adverse events and only one patient having an intraocular pressure of >21 mmHg. Of the 30 eyes that responded to treatment, 8 relapsed, but 22 (73%) entered an extended period of remission, with the Kaplan-Meier estimate of median time to relapse for the whole group being 17 months. The eight eyes that relapsed were reinjected and all responded to treatment. One eye relapsed at 3 months, but 7 eyes again entered extended remission. Of the 14 patients on systemic therapy at the start of the study, 8 (57%) were able to significantly reduce this following intravitreal methotrexate injection. In patients with uveitis and uveitic cystoid macular edema, intravitreal MTX can effectively improve visual acuity and reduce cystoid macular edema and, in some patients, allows the reduction of immunosuppressive therapy. Some patients relapse at 3 to 4 months, but a large proportion (73%) enter an extended period of remission of up to 18 months. This larger study extends the results obtained from previous smaller studies suggesting the viability of intravitreal methotrexate as a treatment option in uveitis.

[Spectral transmission in blue filter intraocular lenses].

PubMed

Schrage, N

2012-02-01

There is uncertainty in ophthalmology concerning the quality and spectral transmission of light of so-called blue filter intraocular lenses (IOL). Clinical users have noticed that such IOL's appear to have different color intensities. The discussion on medical changes by means of such IOL's is dependent on the real light transmission of these IOL's. To add some objective data we compared these IOL's by systematic transmission measurements and observed technical differences of diffraction and geometry as well as transmission differences. The result gives objective indications that differences between blue filter IOL's from different manufacturers are important and are detailed in this paper.

Long-term non-invasive measurement of intraocular pressure in the rat eye.

PubMed

Moore, C G; Epley, D; Milne, S T; Morrison, J C

1995-08-01

To study the optic neuropathy associated with glaucoma, a system for accurate, reliable, and non-invasive monitoring of intraocular pressure (IOP) is required. Of particular interest is the effect of sampling frequency on IOP. To address this issue, ten adult male brown Norway rats (group 1) were acclimatized to a 12-h/12-h light/dark cycle. On 20 days over a 30-day period, rats were anesthetized with short-acting isoflurane (Forane) inhalant anesthesia and IOP for each eye was determined by averaging 15 valid individual readings obtained with a TonoPen 2 tonometer. The last 12 measurement sessions were performed on a daily basis. To determine the minimum tolerable interval between IOP measurement sessions, a second group of 10 animals (group 2) was acclimatized in the same manner as group 1, and IOP was measured every 4 days over a period of 80 days. Next, IOP was measured every 4 days over a period of 28 days, and finally, every 2 days over a period of 19 days. For all group 1 measurements, there was no statistically significant difference between the right and left eye IOP, 14.75 +/- 1.08 (SEM) and 14.90 +/- 1.09 mm Hg, respectively. However, daily measurements produced a steady decrease in IOP and gradual weight loss. For group 2, overall mean right and left eye IOPs were 15.24 +/- 1.28 (SEM) and 15.12 +/- 1.26, respectively and were not significantly different.(ABSTRACT TRUNCATED AT 250 WORDS)

Repeated intraocular crystallization of ganciclovir in one eye after bilateral intravitreal injections: a case report.

PubMed

Iu, Lawrence P L; Fan, Michelle C Y; Lam, Wai-Ching; Wong, Ian Y H

2018-02-09

Cytomegalovirus (CMV) retinitis is an opportunistic infection that primarily affects immunocompromised individuals. Intravitreal ganciclovir injection monotherapy or in combination with systemic anti-CMV therapy are effective treatments for CMV retinitis. Crystallization of ganciclovir after intravitreal injection is extremely rare. Only two cases had been reported in literature. Crystallization in only one eye after bilateral injections had not been reported before. We hereby report a case of intraocular ganciclovir crystallization in one eye after bilateral intravitreal injections, and repeated crystallization in the same eye after repeated injections. A 79-year-old patient had bilateral cytomegalovirus retinitis and received bilateral intravitreal ganciclovir injections of 2.5 mg in 0.05 ml sterile water. Fundus examination after injection showed formation of needle-shaped, golden-yellow crystals in the vitreous of right eye but not in left eye. The crystals dissolved spontaneously. Repeated bilateral intravitreal ganciclovir injections 4 days later resulted in repeated crystallization of ganciclovir in right eye but not in left eye. The crystals dissolved spontaneously and completely after 5 minutes. Visual acuity remained unchanged and intraocular pressure was normal. Intraocular ganciclovir crystallization could occur after intravitreal injections. It is important to perform fundus examination after injection. The crystals may dissolve rapidly and vitrectomy may not be necessary. Our case suggested intraocular ganciclovir crystallization is an idiosyncratic phenomenon, subjects to distinctive intraocular environment which could be different between two eyes of the same patient. The susceptible intraocular environment could be persistent leading to repeated crystallization.

21 CFR 886.4300 - Intraocular lens guide.

Code of Federal Regulations, 2011 CFR

2011-04-01

... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Intraocular lens guide. 886.4300 Section 886.4300...) MEDICAL DEVICES OPHTHALMIC DEVICES Surgical Devices § 886.4300 Intraocular lens guide. (a) Identification. An intraocular lens guide is a device intended to be inserted into the eye during surgery to direct...

Ultra-high speed OCT allows measurement of intraocular pressure, corneal geometry, and corneal stiffness using a single instrument

NASA Astrophysics Data System (ADS)

Singh, Manmohan; Han, Zhaolong; Nair, Achuth; Schill, Alexander; Twa, Michael D.; Larin, Kirill V.

2018-02-01

Screening for ocular diseases, such as glaucoma and keratoconus, includes measuring the eye-globe intraocular pressure (IOP) and corneal biomechanical properties. However, currently available clinical tools cannot quantify corneal tissue material parameters, which can provide critical information for detecting diseases and evaluating therapeutic outcomes. Here, we demonstrate measurement of eye-globe IOP, corneal elasticity, and corneal geometry of in situ porcine corneas with a technique termed applanation optical coherence elastography (Appl-OCE) with single instrument. We utilize an ultrafast phase-sensitive optical coherence tomography system comprised of a 4X buffered Fourier domain mode-locked swept source laser with an Ascan rate of 1.5 MHz and a 7.3 kHz resonant scanner. The IOP was measured by imaging the response of in situ porcine corneas to a large force air-puff. As with other noncontact tonometers, the time when the cornea was applanated during the inwards and outwards motion was correlated to a measure air-pressure temporal profile. The IOP was also measured with a commercially available rebound tonometer for comparison. The stiffness of the corneas was assessed by directly imaging and analyzing the propagation of a focused micro air-pulse induced elastic wave, and the corneal geometry was obtained from the OCT structural image. Our results show that corneal thickness decreased as IOP increased, and that corneal stiffness increased with IOP. Moreover, the IOP measurements made by Appl-OCE were more closely correlated with the artificially set IOP than the rebound tonometer, demonstrating the capabilities of Appl-OCE to measure corneal stiffness, eye-globe IOP, and corneal geometry with a single instrument.

Fault Tolerant Real-Time Systems

DTIC Science & Technology

1993-09-30

The ART (Advanced Real-Time Technology) Project of Carnegie Mellon University is engaged in wide ranging research on hard real - time systems . The...including hardware and software fault tolerance using temporal redundancy and analytic redundancy to permit the construction of real - time systems whose

Postural effects on intraocular pressure and ocular perfusion pressure in patients with non-arteritic anterior ischemic optic neuropathy.

PubMed

Yang, Jee Myung; Park, Sang Woo; Ji, Yong Sok; Kim, Jaeryung; Yoo, Chungkwon; Heo, Hwan

2017-04-20

To investigate postural effects on intraocular pressure (IOP) and ocular perfusion pressure (OPP) in patients with non-arteritic ischemic optic neuropathy (NAION). IOP and blood pressure (BP) were measured in 20 patients with unilateral NAION 10 min after changing to each of the following positions sequentially: sitting, supine, right lateral decubitus position (LDP), supine, left LDP, and supine. IOP was measured using a rebound tonometer and OPP was calculated using formulas based on mean BP. The dependent LDP (DLDP) was defined as the position when the eye of interest (affected or unaffected eye) was placed on the dependent side in the LDP. IOPs were significantly higher (P = 0.020) and OPPs were significantly lower (P = 0.041) in the affected eye compare with the unaffected eye, with the affected eye in DLDP. Compared with the mean IOP of the unaffected eyes, the mean IOP of the affected eyes increased significantly (+2.9 ± 4.4 versus +0.7 ± 3.1 mmHg, respectively; P = 0.003) and the mean OPP decreased significantly (-6.7 ± 9.4 versus -4.9 ± 8.0 mmHg, respectively; P = 0.022) after changing positions from supine to DLDP. In addition, changing position from supine to DLDP showed significantly larger absolute changes in IOP (4.13 ± 3.19 mmHg versus 2.51 ± 1.92 mmHg, respectively; P = 0.004) and OPP (9.86 ± 5.69 mmHg versus 7.50 ± 5.49 mmHg, respectively; P = 0.009) in the affected eye compared with the unaffected eye. In the affected eye, there was a significant positive correlation between absolute change in IOP and OPP when changing position from supine to DLDP (Rho = 0.512, P = 0.021). A postural change from supine to DLDP caused significant fluctuations in IOP and OPP of the affected eye, and may significantly increase IOP and decrease OPP. Posture-induced IOP changes may be a predisposing factor for NAION development.

Glaucoma drops control intraocular pressure and protect optic nerves in a rat model of glaucoma.

PubMed

Morrison, J C; Nylander, K B; Lauer, A K; Cepurna, W O; Johnson, E

1998-03-01

To determine whether chronic topical glaucoma therapy can control intraocular pressure (IOP) and protect nerve fibers in a rat model of pressure-induced optic nerve damage. Sixteen adult Brown Norway rats were-administered unilateral episcleral vein injections of hypertonic saline to produce scarring of the aqueous humor outflow pathways. Twice daily applications of either artificial tears (n = 6), 0.5% betaxolol (n = 5), or 0.5% apraclonidine (n = 5) were delivered to both eyes, and awake pressures were monitored with a TonoPen XL tonometer for 17 days before the rats were killed. For animals administered artificial tears, the mean IOP of the experimental eyes was 39 +/- 2 mm Hg compared with 29 +/- 1 mm Hg for the control eyes. This difference was statistically significant (P < 0.001). Mean IOPs in the experimental eyes of animals administered betaxolol and apraclonidine were 29 +/- 7 and 29 +/- 4 mm Hg, respectively, whereas the mean IOP in the control eyes was 28 +/- 1 mm Hg for both groups. There was no statistically significant difference among these values. The mean IOP for the experimental eyes in the betaxolol and apraclonidine groups was lower than that in animals administered artificial tears (P = 0.003). Quantitative histologic analysis of optic nerve damage in experimental eyes showed that four of the six animals administered artificial tears had damage involving 100% of the neural area. This degree of damage appeared in only 3 of 10 animals administered glaucoma therapy. Optic nerve protection was closely correlated with IOP history because damage was limited to less than 10% of the cross-sectional area in all animals in which the maximal IOP was less than or equal to 39 mm Hg, more than 2 SD below the mean value for eyes administered artificial tears. Topical glaucoma therapy in this model can prevent IOP elevation and protect optic nerve fibers.

Sodium Orthovanadate Effect on Outflow Facility and Intraocular Pressure in Live Monkeys

PubMed Central

Tan, James C.H.; Kiland, Julie A.; Gonzalez, Jose M.; Gabelt, B’Ann T.; Peters, Donna M.; Kaufman, Paul L.

2010-01-01

Sodium orthovanadate (Na3VO4) is reported to reduce IOP by affecting aqueous formation, but whether it also affects outflow facility (OF) is unclear. We tested the effect of Na3VO4 on OF and intraocular pressure (IOP) in live cynomolgus monkeys, and on actin and cell adhesion organization in cultured human trabecular meshwork (HTM) cells. Total OF (n = 12) was measured by 2-level constant pressure perfusion of the monkey anterior chamber (AC) before and after exchange with 1 mM Na3VO4 or vehicle in opposite eyes. Topical 1% Na3VO4 or vehicle only was given twice daily (each 2×20 μL drops) for 4 days to opposite eyes (n = 8), and Goldmann IOP was measured before and hourly after treatment for 6 hours on Days 1 and 4. Filamentous actin and vinculin-containing cell adhesions were examined by epifluorescence microscopy after the cells had been incubated with 1 mM Na3VO4 for 24 hours. A) In monkeys, Na3VO4 increased OF by 29.3 ± 8.8% (mean ± s.e.m.) over the perfusion interval when adjusted for baseline and contralateral eye washout (p = 0.01; n = 12). B) Day 1 baseline IOP was 16.2 ± 1.5 mmHg in treated eyes and 15.9 ± 1.3 mmHg in the contralateral control eyes. Following treatment on Day 1, IOP was no different (p>0.05) between treated eyes and control eyes at any time-point or compared to baseline. Day 4 mean IOP averaged over hours 2–6 was 13.5 ± 0.8 mmHg in treated eyes and 16.1 ± 0.2 mmHg in control eyes. Treated eye IOP was lower than its Day 4 baseline (p<0.005), lower than control eyes for the same Day 4 interval (p = 0.009), and lower than the Day 1 baseline (p = 0.0000). Control eye IOP on Day 4 was not significantly different from baseline on Day 1. C) Incubation of HTM cells with 1 mM Na3VO4 for 24 hours caused a loss of actin stress fibers and vinculin-containing adhesions. Cell retraction and separation was also observed in vanadate-treated cultures. Reformation of actin stress fibers, vinculin-containing adhesions and confluent monolayers

[How does central cornea thickness influence intraocular pressure during applanation and contour tonometry?].

PubMed

Schwenteck, T; Knappe, M; Moros, I

2012-09-01

Golmann applanation tonometry represents a well-established procedure for measuring intraocular pressure (IOP). This implies the necessity of an accurate measurement of IOP with the reference tonometer. One example is the contour tonometer Pascal with a measuring probe, adapted to the cornea geometry, for measuring the IOP and the ocular pulse amplitude. There is controversy of how strongly corneal thickness affects the measurement of IOP. We thus analysed, for a number of eyes, the correlation of IOP, as measured by two types of applanation tonometers and one contour tonometer and the central corneal thickness. In all 158 patient eyes were investigated in a clinical comparison of applanation tonometers AT 870 and Ocuton-A. The study was performed by a trained ophthalmologist and the comparison was in accordance with international standard ISO 8612. In addition, the corneal thickness in the vertex was repeatedly determined using an Oculus Pentacam. The potential effect of central corneal thickness on the IOP as measured by the mentioned tonometers was statistically evaluated by rank correlation analysis. We found that the measured IOP values for the three investigated tonometers were not normally distributed. The central corneal thickness values, in contrast, measured on 158 eyes by means of an ultrasound pachymeter and additionally on 235 eyes by the Pentacam, obeyed a Gaussian distribution. For the correlation analysis of both parameters the Spearman linear rank correlation coefficient (r) was considered. We found a very weak (|r| < 0.2) correlation between central corneal thickness and IOP for all 3 tonometers. The softness of the correlation is also illustrated by a large standard deviation of the regression line. A comparison of the different devices for corneal-thickness measurements shows less variance and a smaller variation coefficient when the ultrasoundpachymeter AL-1000 is used. The measured values for IOP are only very weakly correlated to the central

Real-time implementation of biofidelic SA1 model for tactile feedback.

PubMed

Russell, A F; Armiger, R S; Vogelstein, R J; Bensmaia, S J; Etienne-Cummings, R

2009-01-01

In order for the functionality of an upper-limb prosthesis to approach that of a real limb it must be able to, accurately and intuitively, convey sensory feedback to the limb user. This paper presents results of the real-time implementation of a 'biofidelic' model that describes mechanotransduction in Slowly Adapting Type 1 (SA1) afferent fibers. The model accurately predicts the timing of action potentials for arbitrary force or displacement stimuli and its output can be used as stimulation times for peripheral nerve stimulation by a neuroprosthetic device. The model performance was verified by comparing the predicted action potential (or spike) outputs against measured spike outputs for different vibratory stimuli. Furthermore experiments were conducted to show that, like real SA1 fibers, the model's spike rate varies according to input pressure and that a periodic 'tapping' stimulus evokes periodic spike outputs.

The effects of anesthesia and gender on intraocular pressure in lions (Panthera leo).

PubMed

Ofri, R; Horowitz, I; Jacobson, S; Kass, P H

1998-09-01

Intraocular pressure (IOP) was measured in a pride of 22 (11 males, 11 females) lions (Panthera leo) using a Schiotz tonometer. Two anesthetic protocols were used in the study. Lions in group I (n = 14) were anesthetized using xylazine, atropine sulfate, and ketamine. Lions in group II (n = 8) were anesthetized using ketamine and diazepam. Five sequential readings were taken from each eye of every lion. There were no significant differences in IOP between the two anesthetic groups, between left and right eyes, or over the five readings. The IOP was significantly higher in males than in females, controlling for age and weight. The mean (+/-SD) tonometer reading in 22 eyes of 11 male lions was 2.9 (+/-0.5) mm; with a 95% confidence interval (CI) of 1.6-4.5 mm. The mean tonometer reading in 22 eyes of 11 female lions was 4.0 (+/-0.7) mm, with a 95% CI of 1.8-6.3 mm. Using the 1955 Friedenwald human calibration table, the estimated mean IOP in 22 eyes of 11 male lions was 24.9 (+/-2.0) mm Hg, with a 95% CI of 20.4-29.4 mm Hg. The estimated mean IOP in 22 eyes of 11 female lions was 20.9 (+/-2.4) mm Hg, with a 95% CI of 15.6-26.3 mm Hg.

Corneal biomechanical changes in diabetes mellitus and their influence on intraocular pressure measurements.

PubMed

Sahin, Afsun; Bayer, Atilla; Ozge, Gökhan; Mumcuoğlu, Tarkan

2009-10-01

To investigate possible corneal biomechanical changes in patients with diabetes mellitus and understand the influence of such changes on intraocular pressure measurements. The study group was composed of 120 eyes from 61 healthy control subjects and 81 eyes from 43 diabetic subjects. IOP was measured first with an ocular response analyzer (ORA) and subsequently with a Goldmann applanation tonometer (GAT). Central corneal thickness (CCT) was measured with an ultrasonic pachymeter attached to the ORA. Axial length (AL), anterior chamber depth (ACD), and keratometry readings were acquired with partial coherence laser interferometry during the same visit before all IOP and CCT determinations were made. Corneal hysteresis (CH) was found to be significantly lower in diabetic patients when compared with healthy control subjects (9.51 +/- 1.82 mm Hg vs. 10.41 +/- 1.66 mm Hg, P < 0.0001). There was no significant difference in terms of corneal resistance factor (CRF; P = 0.8). Mean CCT, GAT IOP, Goldmann-correlated IOP (IOPg), and corneal-compensated IOP (IOPcc) were significantly higher in diabetic patients than in healthy control subjects (P = 0.01 for CCT, P < 0.0001 for GAT IOP, IOPg, and IOPcc). Diabetes affects corneal biomechanics and results in lower CH values than those in healthy control subjects, which may cause clinically relevant high IOP measurements independent of CCT.

Tear production and intraocular pressure in canine eyes with corneal ulceration

PubMed Central

Williams, David L.; Burg, Philippa

2017-01-01

This study aimed to evaluate changes in lacrimation and intraocular pressure (IOP) in dogs with unilateral corneal ulceration using the Schirmer tear test (STT) and rebound (TonoVet®) tonometry. IOP and STT values were recorded in both ulcerated and non-ulcerated (control) eyes of 100 dogs diagnosed with unilateral corneal ulceration. Dogs presented with other ocular conditions as their primary complaint were excluded from this study. The mean ± standard deviation for STT values in the ulcerated and control eyes were 20.2±4.6 mm/min and 16.7±3.5 mm/min respectively. The mean ± standard deviation for IOP in the ulcerated and control eyes were 11.9±3.1 mmHg and 16.7±2.6 mmHg respectively. STT values were significantly higher (p<0.000001) in the ulcerated eye compared to the control eye while IOP was significantly lower (p<0.0001). There is an increase in lacrimation and a decrease in IOP in canine eyes with corneal ulceration. The higher tear production in ulcerated eyes shows the importance of measuring STT in both eyes in cases of corneal ulceration, since this increased lacrimation may mask an underlying keratoconjunctivitis sicca only evident in the contralateral eye. The lower IOP in ulcerated eyes is likely to relate to mild uveitic change in the ulcerated eye with a concomitant increase in uveoscleral aqueous drainage. While these changes in tear production and IOP in ulcerated eyes are widely recognised in both human and veterinary ophthalmology, it appears that this is the first controlled documented report of these changes in a large number of individuals. PMID:28616393

EX VIVO MODEL FOR THE CHARACTERIZATION AND IDENTIFICATION OF DRYWALL INTRAOCULAR FOREIGN BODIES ON COMPUTED TOMOGRAPHY.

PubMed

Syed, Reema; Kim, Sung-Hye; Palacio, Agustina; Nunery, William R; Schaal, Shlomit

2017-06-06

The study was inspired after the authors encountered a patient with a penetrating globe injury due to drywall, who had retained intraocular drywall foreign body. Computed tomography (CT) was read as normal in this patient. Open globe injury with drywall has never been reported previously in the literature and there are no previous studies describing its radiographic features. The case report is described in detail elsewhere. This was an experimental study. An ex vivo model of 15 porcine eyes with 1 mm to 5 mm fragments of implanted drywall, 2 vitreous only samples with drywall and 3 control eyes were used. Eyes and vitreous samples were CT scanned on Days 0, 1, and 3 postimplantation. Computed ocular images were analyzed by masked observers. Size and radiodensity of intraocular drywall were measured using Hounsfield units (HUs) over time. Intraocular drywall was hyperdense on CT. All sizes studied were detectable on Day 0 of scanning. Mean intraocular drywall foreign body density was 171 ± 52 Hounsfield units (70-237) depending on fragment size. Intraocular drywall foreign body decreased in size whereas Hounsfield unit intensity increased over time. Drywall dissolves in the eye and becomes denser over time as air in the drywall is replaced by fluid. This study identified Hounsfield Units specific to intraocular drywall foreign body over time.

Real-Time Strap Pressure Sensor System for Powered Exoskeletons

PubMed Central

Tamez-Duque, Jesús; Cobian-Ugalde, Rebeca; Kilicarslan, Atilla; Venkatakrishnan, Anusha; Soto, Rogelio; Contreras-Vidal, Jose Luis

2015-01-01

Assistive and rehabilitative powered exoskeletons for spinal cord injury (SCI) and stroke subjects have recently reached the clinic. Proper tension and joint alignment are critical to ensuring safety. Challenges still exist in adjustment and fitting, with most current systems depending on personnel experience for appropriate individual fastening. Paraplegia and tetraplegia patients using these devices have impaired sensation and cannot signal if straps are uncomfortable or painful. Excessive pressure and blood-flow restriction can lead to skin ulcers, necrotic tissue and infections. Tension must be just enough to prevent slipping and maintain posture. Research in pressure dynamics is extensive for wheelchairs and mattresses, but little research has been done on exoskeleton straps. We present a system to monitor pressure exerted by physical human-machine interfaces and provide data about levels of skin/body pressure in fastening straps. The system consists of sensing arrays, signal processing hardware with wireless transmission, and an interactive GUI. For validation, a lower-body powered exoskeleton carrying the full weight of users was used. Experimental trials were conducted with one SCI and one able-bodied subject. The system can help prevent skin injuries related to excessive pressure in mobility-impaired patients using powered exoskeletons, supporting functionality, independence and better overall quality of life. PMID:25690551

Real-time strap pressure sensor system for powered exoskeletons.

PubMed

Tamez-Duque, Jesús; Cobian-Ugalde, Rebeca; Kilicarslan, Atilla; Venkatakrishnan, Anusha; Soto, Rogelio; Contreras-Vidal, Jose Luis

2015-02-16

Assistive and rehabilitative powered exoskeletons for spinal cord injury (SCI) and stroke subjects have recently reached the clinic. Proper tension and joint alignment are critical to ensuring safety. Challenges still exist in adjustment and fitting, with most current systems depending on personnel experience for appropriate individual fastening. Paraplegia and tetraplegia patients using these devices have impaired sensation and cannot signal if straps are uncomfortable or painful. Excessive pressure and blood-flow restriction can lead to skin ulcers, necrotic tissue and infections. Tension must be just enough to prevent slipping and maintain posture. Research in pressure dynamics is extensive for wheelchairs and mattresses, but little research has been done on exoskeleton straps. We present a system to monitor pressure exerted by physical human-machine interfaces and provide data about levels of skin/body pressure in fastening straps. The system consists of sensing arrays, signal processing hardware with wireless transmission, and an interactive GUI. For validation, a lower-body powered exoskeleton carrying the full weight of users was used. Experimental trials were conducted with one SCI and one able-bodied subject. The system can help prevent skin injuries related to excessive pressure in mobility-impaired patients using powered exoskeletons, supporting functionality, independence and better overall quality of life.

Fundus autofluorescence patterns in primary intraocular lymphoma.

PubMed

Casady, Megan; Faia, Lisa; Nazemzadeh, Maryam; Nussenblatt, Robert; Chan, Chi-Chao; Sen, H Nida

2014-02-01

To evaluate fundus autofluorescence (FAF) patterns in patients with primary intraocular (vitreoretinal) lymphoma. Records of all patients with primary intraocular lymphoma who underwent FAF imaging at the National Eye Institute were reviewed. Fundus autofluorescence patterns were evaluated with respect to clinical disease status and the findings on fluorescein angiography and spectral-domain optical coherence tomography. There were 18 eyes (10 patients) with primary intraocular lymphoma that underwent FAF imaging. Abnormal autofluorescence in the form of granular hyperautofluorescence and hypoautofluorescence was seen in 11 eyes (61%), and blockage by mass lesion was seen in 2 eyes (11%). All eyes with granular pattern on FAF had active primary intraocular lymphoma at the time of imaging, but there were 5 eyes with unremarkable FAF, which were found to have active lymphoma. The most common pattern on fluorescein angiography was hypofluorescent round spots with a "leopard spot" appearance (43%). These hypofluorescent spots on fluorescein angiography correlated with hyperautofluorescent spots on FAF in 5 eyes (36%) (inversion of FAF). Nodular hyperreflective spots at the level of retinal pigment epithelium on optical coherence tomography were noted in 43% of eyes. The hyperautofluorescent spots on FAF correlated with nodular hyperreflective spots on optical coherence tomography in 6 eyes (43%). Granularity on FAF was associated with active lymphoma in majority of the cases. An inversion of FAF (hyperautofluorescent spots on FAF corresponding to hypofluorescent spots on fluorescein angiography) was observed in less than half of the eyes.

VERSE - Virtual Equivalent Real-time Simulation

NASA Technical Reports Server (NTRS)

Zheng, Yang; Martin, Bryan J.; Villaume, Nathaniel

2005-01-01

Distributed real-time simulations provide important timing validation and hardware in the- loop results for the spacecraft flight software development cycle. Occasionally, the need for higher fidelity modeling and more comprehensive debugging capabilities - combined with a limited amount of computational resources - calls for a non real-time simulation environment that mimics the real-time environment. By creating a non real-time environment that accommodates simulations and flight software designed for a multi-CPU real-time system, we can save development time, cut mission costs, and reduce the likelihood of errors. This paper presents such a solution: Virtual Equivalent Real-time Simulation Environment (VERSE). VERSE turns the real-time operating system RTAI (Real-time Application Interface) into an event driven simulator that runs in virtual real time. Designed to keep the original RTAI architecture as intact as possible, and therefore inheriting RTAI's many capabilities, VERSE was implemented with remarkably little change to the RTAI source code. This small footprint together with use of the same API allows users to easily run the same application in both real-time and virtual time environments. VERSE has been used to build a workstation testbed for NASA's Space Interferometry Mission (SIM PlanetQuest) instrument flight software. With its flexible simulation controls and inexpensive setup and replication costs, VERSE will become an invaluable tool in future mission development.

Phakic iris-fixated intraocular lens placement in the anterior chamber: effects on aqueous flow.

PubMed

Repetto, Rodolfo; Pralits, Jan O; Siggers, Jennifer H; Soleri, Paolo

2015-05-01

Phakic intraocular lenses (pIOLs) are used for correcting vision; in this paper we investigate the fluid dynamical effects of an iris-fixated lens in the anterior chamber. In particular, we focus on changes in the wall shear stress (WSS) on the cornea and iris, which could be responsible for endothelial and pigment cell loss, respectively, and also on the possible increase of the intraocular pressure, which is known to correlate with the incidence of secondary glaucoma. We use a mathematical model to study fluid flow in the anterior chamber in the presence of a pIOL. The governing equations are solved numerically using the open source software OpenFOAM. We use an idealized standard geometry for the anterior chamber and a realistic geometric description of the pIOL. We consider separately the main mechanisms that produce fluid flow in the anterior chamber. The numerical simulations allow us to obtain a detailed description of the velocity and pressure distribution in the anterior chamber, and indicated that implantation of the pIOL significantly modifies the fluid dynamics in the anterior chamber. However, lens implantation has negligible influence on the intraocular pressure and does not produce a significant increase of the shear stress on the cornea, while the shear stress on the iris, although increased, is not enough to cause detachment of cells. We conclude that alterations in the fluid dynamics in the anterior chamber as a result of lens implantation are unlikely to be the cause of medical complications associated with its use.

Population-based Incidence of Intraocular Lens Exchange in Olmsted County, Minnesota.

PubMed

Bothun, Erick D; Cavalcante, Lilian C B; Hodge, David O; Patel, Sanjay V

2018-03-01

To determine the population-based incidence of pseudophakic intraocular lens exchange in Olmsted County, Minnesota. Retrospective review of a population-based cohort. Patients undergoing pseudophakic intraocular lens exchange in Olmsted County, Minnesota, between January 1, 1986 and December 31, 2016 were identified from the Rochester Epidemiology Project medical record linkage system. Indications and outcomes were determined, and the incidence rate was calculated as cases per 1 000 000 person-years. Poisson regression analysis was used to assess changes in incidence over time, and the cumulative probability of needing a lens exchange was estimated by Kaplan-Meier analysis. Eighty cases of intraocular lens exchange were identified, yielding an overall age- and sex-adjusted incidence rate of 28.4 per million (confidence interval [CI], 22.1-34.7), which increased over the study period (P = .04). The 30-year cumulative probability of intraocular lens exchange among patients undergoing cataract surgery was 1.5% (CI, 0.6%-2.4%), increasing at a relatively constant rate. Dislocated lenses accounted for 72.5% of lens exchanges. Unplanned refractive outcome of primary cataract surgery and uveitis-glaucoma-hyphema syndrome from squared-edged haptics emerged as newer indications for intraocular lens exchange. The population-based incidence of pseudophakic intraocular lens exchange has increased over the last 30 years, and can be explained by the increase in incidence rate of cataract surgery over the same period. Surgeons should be aware of emerging indications of intraocular lens exchange, which reflect changes in lens design and increasing expectations of refractive outcomes. Copyright © 2017 Elsevier Inc. All rights reserved.

Real-time contaminant sensing and control in civil infrastructure systems

NASA Astrophysics Data System (ADS)

Rimer, Sara; Katopodes, Nikolaos

2014-11-01

A laboratory-scale prototype has been designed and implemented to test the feasibility of real-time contaminant sensing and control in civil infrastructure systems. A blower wind tunnel is the basis of the prototype design, with propylene glycol smoke as the ``contaminant.'' A camera sensor and compressed-air vacuum nozzle system is set up at the test section portion of the prototype to visually sense and then control the contaminant; a real-time controller is programmed to read in data from the camera sensor and administer pressure to regulators controlling the compressed air operating the vacuum nozzles. A computational fluid dynamics model is being integrated in with this prototype to inform the correct pressure to supply to the regulators in order to optimally control the contaminant's removal from the prototype. The performance of the prototype has been evaluated against the computational fluid dynamics model and is discussed in this presentation. Furthermore, the initial performance of the sensor-control system implemented in the test section of the prototype is discussed. NSF-CMMI 0856438.

Long-term intraocular pressure changes in patients with neovascular age-related macular degeneration treated with ranibizumab.

PubMed

Menke, Marcel N; Salam, Adzura; Framme, Carsten; Wolf, Sebastian

2013-01-01

To investigate the long-term effects of multiple intravitreal injections (IVTs) of ranibizumab (Lucentis) on intraocular pressure (IOP) in patients with neovascular age-related macular degeneration. In 320 eyes, IOP measurements were performed at baseline prior to injection and compared with IOP measurements of the last visit. Correlations between mean IOP change and total number of IVTs, visual acuity or patient age were tested. The mean IOP increase was 0.8 ± 3.1 mm Hg (p < 0.0001). Seven eyes showed final IOP values between 22 and 25 mm Hg. The mean follow-up was 22.7 ± 14.1 months. No further correlations between IOP change and number of IVTs, visual acuity or patient age have been found. This study demonstrated a statistically significant IOP increase in patients treated with repeated injections of ranibizumab. However, IOP increase required no glaucoma treatment during the study. Therefore, repeated injections with ranibizumab can be considered safe with regard to long-term IOP changes in patients without ocular hypertension or glaucoma. Copyright © 2013 S. Karger AG, Basel.

Genome-wide analysis of multiethnic cohorts identifies new loci influencing intraocular pressure and susceptibility to glaucoma

PubMed Central

Vitart, Veronique; Nag, Abhishek; Hewitt, Alex W; Höhn, René; Venturini, Cristina; Mirshahi, Alireza; Ramdas, Wishal D.; Thorleifsson, Gudmar; Vithana, Eranga; Khor, Chiea-Chuen; Stefansson, Arni B; Liao, Jiemin; Haines, Jonathan L; Amin, Najaf; Wang, Ya Xing; Wild, Philipp S; Ozel, Ayse B; Li, Jun Z; Fleck, Brian W; Zeller, Tanja; Staffieri, Sandra E; Teo, Yik-Ying; Cuellar-Partida, Gabriel; Luo, Xiaoyan; Allingham, R Rand; Richards, Julia E; Senft, Andrea; Karssen, Lennart C; Zheng, Yingfeng; Bellenguez, Céline; Xu, Liang; Iglesias, Adriana I; Wilson, James F; Kang, Jae H; van Leeuwen, Elisabeth M; Jonsson, Vesteinn; Thorsteinsdottir, Unnur; Despriet, Dominiek D.G.; Ennis, Sarah; Moroi, Sayoko E; Martin, Nicholas G; Jansonius, Nomdo M; Yazar, Seyhan; Tai, E-Shyong; Amouyel, Philippe; Kirwan, James; van Koolwijk, Leonieke M.E.; Hauser, Michael A; Jonasson, Fridbert; Leo, Paul; Loomis, Stephanie J; Fogarty, Rhys; Rivadeneira, Fernando; Kearns, Lisa; Lackner, Karl J; de Jong, Paulus T.V.M.; Simpson, Claire L; Pennell, Craig E; Oostra, Ben A; Uitterlinden, André G; Saw, Seang-Mei; Lotery, Andrew J; Bailey-Wilson, Joan E; Hofman, Albert; Vingerling, Johannes R; Maubaret, Cécilia; Pfeiffer, Norbert; Wolfs, Roger C.W.; Lemij, Hans G; Young, Terri L; Pasquale, Louis R; Delcourt, Cécile; Spector, Timothy D; Klaver, Caroline C.W.; Small, Kerrin S; Burdon, Kathryn P; Stefansson, Kari; Wong, Tien-Yin; Viswanathan, Ananth; Mackey, David A; Craig, Jamie E; Wiggs, Janey L; van Duijn, Cornelia M; Hammond, Christopher J; Aung, Tin

2014-01-01

Elevated intraocular pressure (IOP) is an important risk factor in developing glaucoma and IOP variability may herald glaucomatous development or progression. We report the results of a genome-wide association study meta-analysis of 18 population cohorts from the International Glaucoma Genetics Consortium (IGGC), comprising 35,296 multiethnic participants for IOP. We confirm genetic association of known loci for IOP and primary open angle glaucoma (POAG) and identify four new IOP loci located on chromosome 3q25.31 within the FNDC3B gene (p=4.19×10−08 for rs6445055), two on chromosome 9 (p=2.80×10−11 for rs2472493 near ABCA1 and p=6.39×10−11 for rs8176693 within ABO) and one on chromosome 11p11.2 (best p=1.04×10−11 for rs747782). Separate meta-analyses of four independent POAG cohorts, totaling 4,284 cases and 95,560 controls, show that three of these IOP loci are also associated with POAG. PMID:25173106

Developments in real-time monitoring for geologic hazard warnings (Invited)

NASA Astrophysics Data System (ADS)

Leith, W. S.; Mandeville, C. W.; Earle, P. S.

2013-12-01

Real-time data from global, national and local sensor networks enable prompt alerts and warnings of earthquakes, tsunami, volcanic eruptions, geomagnetic storms , broad-scale crustal deformation and landslides. State-of-the-art seismic systems can locate and evaluate earthquake sources in seconds, enabling 'earthquake early warnings' to be broadcast ahead of the damaging surface waves so that protective actions can be taken. Strong motion monitoring systems in buildings now support near-real-time structural damage detection systems, and in quiet times can be used for state-of-health monitoring. High-rate GPS data are being integrated with seismic strong motion data, allowing accurate determination of earthquake displacements in near-real time. GPS data, combined with rainfall, groundwater and geophone data, are now used for near-real-time landslide monitoring and warnings. Real-time sea-floor water pressure data are key for assessing tsunami generation by large earthquakes. For monitoring remote volcanoes that lack local ground-based instrumentation, the USGS uses new technologies such as infrasound arrays and the worldwide lightning detection array to detect eruptions in progress. A new real-time UV-camera system for measuring the two dimensional SO2 flux from volcanic plumes will allow correlations with other volcano monitoring data streams to yield fundamental data on changes in gas flux as an eruption precursor, and how magmas de-gas prior to and during eruptions. Precision magnetic field data support the generation of real-time indices of geomagnetic disturbances (Dst, K and others), and can be used to model electrical currents in the crust and bulk power system. Ground-induced electrical current monitors are used to track those currents so that power grids can be effectively managed during geomagnetic storms. Beyond geophysical sensor data, USGS is using social media to rapidly detect possible earthquakes and to collect firsthand accounts of the impacts of

Near real time determination of the magnetopause and bow shock shape and position

NASA Astrophysics Data System (ADS)

Kartalev, M. D.; Keremidarska, V. I.; Grigorov, K. G.; Romanov, D. K.

2002-03-01

We present a web based near real time (once in 90 minutes) automated running of our 3D magnetosheath gasdynamic numerical model. (http://geospace.nat.bg). The determination of the shape and position of the bow shock and the magnetopause is a part of the solution. This approach of the model is utilizing the realistic semi-empirical Tsyganenko magnetosphere model T96-01 for ensuring the pressure balance at the magnetopause. In this realization, we use a real time ACE data, averaged over a 6 minutes time interval.

Development and Test of an Infrastructure Free Real-Time Water Level Measurement System

NASA Astrophysics Data System (ADS)

Breuer, E. R.; Heitsenrether, R.; Hensley, W., III; Krug, W.; Wolcott, D.

2016-02-01

NOAA's Center for Operational Oceanographic Products and Services (CO-OPS) is responsible for developing and maintaining the National Water Level Observation Network (NWLON). NWLON consists of over 200 long term observatories that provide near real-time, 6 minute average, water level observations from locations throughout all U.S. coasts. CO-OPS continually analyzes state-of-the-art and emerging technologies to identify potential improvements in data quality and operating efficiency. NOAA, recognizing the changing conditions, anticipates a critical need for real time oceanographic and meteorological observations where traditional approaches are less feasible. CO-OPS is working on the design, development and testing of a real-time tidal measurement system, "The Hermit," for use in coastal regions. The latest prototype has recently completed a successful 3 month field test deployment in the St Andrews Sound region of Georgia, a location where relatively few long term water level records have been collected to date. The test location provided unique challenges such as having a very limited coastal infrastructure and experiencing a 7-8 foot tidal range. The Hermit consists of a bottom mounted pressure/conductivity/temperature sensor (Seabird SBE 26+) and a surface communications buoy which are linked via acoustic modems (Link Quest). The surface buoy relays data back to the CO-OPS database in near-real time using an Iridium satellite based communication system. Additionally, the buoy includes an AirMar all-in-one meteorological sensor. In addition to The Hermit deployment, three test GPS bench marks and a tide staff were installed on a nearby coastline to vertically reference water level measurements. During this deployment, The Hermit successfully provided near real-time measurements of bottom pressure, water conductivity and temperature, wind speed and direction, air temperature, and barometric pressure over the 3 month deployment. During the test period, several

NDBC - NDBC Real-Time Data

Science.gov Websites

Subtropical Storm Alberto. NDBC Real-Time Data NDBC moored buoy, C-MAN, and drifting buoy data are available in real-time through selecting either: NDBC Station locator map: a series of regional maps which show : a tabular list of station identifiers. Real-time data are available for the last 45 days (at least

[Intraocular osteosarcoma in a dog].

PubMed

Wiesner, L; Schröder, S; Gralla, S; Goeck, D; Kramer, M; Ondreka, N

2014-01-01

The present case describes the diagnostic and therapeutic procedure of a dog with an intraocular osteosarcoma. According to the results of the diagnostic imaging studies, the tentative diagnosis of an intraocular neoplasm with perforation of the globe and orbital invasion of the tumour was made and an orbital exenteration was performed. The histopathological diagnosis of the extracted organ implied an intraocular, extraskeletal osteosarcoma. Seventy-seven days later the patient displayed an acute paraparesis. Clinical and diagnostic reevaluation using magnetic resonance imaging (MRI) was performed and the dog was euthanized at the owner's request. By means of MRI and necropsy, an additional axial osteosarcoma of the 6th lumbar vertebra and a malignant melanoma of the right tonsil were diagnosed.

Rabbit cornea microstructure response to changes in intraocular pressure visualized by using nonlinear optical microscopy.

PubMed

Wu, Qiaofeng; Yeh, Alvin T

2008-02-01

To characterize the microstructural response of the rabbit cornea to changes in intraocular pressure (IOP) by using nonlinear optical microscopy (NLOM). Isolated rabbit corneas were mounted on an artificial anterior chamber in series with a manometer and were hydrostatically pressurized by a reservoir. The chamber was mounted on an upright microscope stage of a custom-built NLOM system for corneal imaging without using exogenous stains or dyes. Second harmonic generation in collagen was used to image through the full thickness of the central corneal stroma at IOPs between 5 and 20 mm Hg. Microstructural morphology changes as a function of IOP were used to characterize the depth-dependent response of the central cornea. Regional collagen lamellae architecture through the full thickness of the stroma was specifically imaged as a function of IOP. Hypotensive corneas showed gaps between lamellar structures that decreased in size with increasing IOP. These morphologic features appear to result from interwoven lamellae oriented along the anterior-posterior axis and parallel to the cornea surface. They appear throughout the full thickness and disappear with tension in the anterior but persist in the posterior central cornea, even at hypertensive IOP. NLOM reveals interwoven collagen lamellae sheets through the full thickness of the rabbit central cornea oriented along the anterior-posterior axis and parallel to the surface. The nondestructive nature of NLOM allows 3-dimensional imaging of stromal architecture as a function of IOP in situ. Collagen morphologic features were used as an indirect measure of depth-dependent mechanical response to changes in IOP.

Systemic Medication and Intraocular Pressure in a British Population

PubMed Central

Khawaja, Anthony P.; Chan, Michelle P.Y.; Broadway, David C.; Garway-Heath, David F.; Luben, Robert; Yip, Jennifer L.Y.; Hayat, Shabina; Wareham, Nicholas J.; Khaw, Kay-Tee; Foster, Paul J.

2014-01-01

Objective To determine the association between systemic medication use and intraocular pressure (IOP) in a population of older British men and women. Design Population-based, cross-sectional study. Participants We included 7093 participants from the European Prospective Investigation into Cancer–Norfolk Eye Study. Exclusion criteria were a history of glaucoma therapy (medical, laser, or surgical), IOP asymmetry between eyes of >5 mmHg, and missing data for any covariables. The mean age of participants was 68 years (range, 48–92) and 56% were women. Methods We measured IOP using the Ocular Response Analyzer. Three readings were taken per eye and the best signal value of the Goldmann-correlated IOP value considered. Participants were asked to bring all their medications and related documentation to the health examination, and these were recorded by the research nurse using an electronic case record form. The medication classes examined were angiotensin-converting enzyme inhibitors, angiotensin-receptor blockers, α-blockers, β-blockers, calcium channel blockers, diuretics, nitrates, statins, insulin, biguanides, sulfonylureas, aspirin, and other nonsteroidal anti-inflammatory drugs. We examined associations between medication use and IOP using multivariable linear regression models adjusted for age, sex, and body mass index. Models containing diabetic medication were further adjusted for glycosylated hemoglobin levels. Main Outcome Measures Mean IOP of the right and left eyes. Results Use of systemic β-blockers (−0.92 mmHg; 95% CI, −1.19, −0.65; P<0.001) and nitrates (−0.63 mmHg; 95% CI, −1.12, −0.14; P = 0.011) were independently associated with lower IOP. The observed associations between statin or aspirin use with IOP were no longer significant after adjustment for β-blocker use. Conclusions This is the first population-based study to demonstrate and quantify clinically significant differences in IOP among participants using systemic �

Real-Time Simulation

NASA Technical Reports Server (NTRS)

1997-01-01

Coryphaeus Software, founded in 1989 by former NASA electronic engineer Steve Lakowske, creates real-time 3D software. Designer's Workbench, the company flagship product, is a modeling and simulation tool for the development of both static and dynamic 3D databases. Other products soon followed. Activation, specifically designed for game developers, allows developers to play and test the 3D games before they commit to a target platform. Game publishers can shorten development time and prove the "playability" of the title, maximizing their chances of introducing a smash hit. Another product, EasyT, lets users create massive, realistic representation of Earth terrains that can be viewed and traversed in real time. Finally, EasyScene software control the actions among interactive objects within a virtual world. Coryphaeus products are used on Silican Graphics workstation and supercomputers to simulate real-world performance in synthetic environments. Customers include aerospace, aviation, architectural and engineering firms, game developers, and the entertainment industry.

Real-time Tsunami Inundation Prediction Using High Performance Computers

NASA Astrophysics Data System (ADS)

Oishi, Y.; Imamura, F.; Sugawara, D.

2014-12-01

Recently off-shore tsunami observation stations based on cabled ocean bottom pressure gauges are actively being deployed especially in Japan. These cabled systems are designed to provide real-time tsunami data before tsunamis reach coastlines for disaster mitigation purposes. To receive real benefits of these observations, real-time analysis techniques to make an effective use of these data are necessary. A representative study was made by Tsushima et al. (2009) that proposed a method to provide instant tsunami source prediction based on achieving tsunami waveform data. As time passes, the prediction is improved by using updated waveform data. After a tsunami source is predicted, tsunami waveforms are synthesized from pre-computed tsunami Green functions of linear long wave equations. Tsushima et al. (2014) updated the method by combining the tsunami waveform inversion with an instant inversion of coseismic crustal deformation and improved the prediction accuracy and speed in the early stages. For disaster mitigation purposes, real-time predictions of tsunami inundation are also important. In this study, we discuss the possibility of real-time tsunami inundation predictions, which require faster-than-real-time tsunami inundation simulation in addition to instant tsunami source analysis. Although the computational amount is large to solve non-linear shallow water equations for inundation predictions, it has become executable through the recent developments of high performance computing technologies. We conducted parallel computations of tsunami inundation and achieved 6.0 TFLOPS by using 19,000 CPU cores. We employed a leap-frog finite difference method with nested staggered grids of which resolution range from 405 m to 5 m. The resolution ratio of each nested domain was 1/3. Total number of grid points were 13 million, and the time step was 0.1 seconds. Tsunami sources of 2011 Tohoku-oki earthquake were tested. The inundation prediction up to 2 hours after the

Characterization of real-time computers

NASA Technical Reports Server (NTRS)

Shin, K. G.; Krishna, C. M.

1984-01-01

A real-time system consists of a computer controller and controlled processes. Despite the synergistic relationship between these two components, they have been traditionally designed and analyzed independently of and separately from each other; namely, computer controllers by computer scientists/engineers and controlled processes by control scientists. As a remedy for this problem, in this report real-time computers are characterized by performance measures based on computer controller response time that are: (1) congruent to the real-time applications, (2) able to offer an objective comparison of rival computer systems, and (3) experimentally measurable/determinable. These measures, unlike others, provide the real-time computer controller with a natural link to controlled processes. In order to demonstrate their utility and power, these measures are first determined for example controlled processes on the basis of control performance functionals. They are then used for two important real-time multiprocessor design applications - the number-power tradeoff and fault-masking and synchronization.

Muscular Strength Is Associated with Higher Intraocular Pressure in Physically Active Males.

PubMed

Vera, Jesús; Jiménez, Raimundo; García-Ramos, Amador; Cárdenas, David

2018-02-01

The positive association between intraocular pressure (IOP) and relative maximum force may have relevance for exercise recommendations when IOP is a concern. The relationship between exercise and IOP has been approached in several studies. However, the influence of muscle function on IOP remains underexplored. This study aimed to determine the relationship between the maximal mechanical capabilities of muscles to generate force, velocity, and power with IOP. Sixty-five physically active males participated in this cross-sectional study. Baseline IOP measures were obtained by rebound tonometry, and participants performed an incremental loading test in the ballistic bench press. Baseline IOP showed a strong positive correlation with relative maximum force (r65 = 0.85, P < .001) relative maximum power (r65 = 0.85, P < .001), and relative one-repetition maximum (r65 = 0.91, P < .001). Also, a moderate positive association was obtained between baseline IOP and maximum force (r65 = 0.74, P < .001), maximum power (r65 = 0.72, P < .001), and maximum dynamic strength (r65 = 0.80, P < .001). No significant correlations between IOP and maximal velocity were obtained (all P > .05). There is a positive association between greater upper-body power and strength with higher baseline IOP, which might have important implications in the management of ocular health and especially in individuals constantly involved in resistance training programs (e.g., military personnel, weightlifters). The possible protective effect of high fitness level on the acute IOP response to strength exercise needs to be addressed in future studies.

Novel Gonioscopy Score and Predictive Factors for Intraocular Pressure Lowering After Phacoemulsification.

PubMed

Perez, Claudio I; Chansangpetch, Sunee; Feinstein, Max; Mora, Marta; Nguyen, Anwell; Badr, Mai; Masis, Marisse; Lin, Shan C

2018-05-04

To evaluate a novel gonioscopy score as a potential predictor for intraocular pressure (IOP) reduction after cataract surgery. Prospective study that included consecutive patients with or without glaucoma, either with open or narrow angles but without peripheral anterior synechiae, who underwent phacoemulsification. Eyes with intraoperative complications and secondary glaucoma were excluded. A preoperative gonioscopy score was created, summing the Shaffer gonioscopy grading in 4 quadrants (range 0-16). To determine variables associated with IOP change at 6 months, univariate and multivariate linear mixed-effects regression analysis was performed adjusting for age, sex, and preoperative IOP. 188 eyes from 137 patients were enrolled. The mean age of the patients was 75.0 (±8.5) years and the average preoperative IOP was 15.6 (±3.6) mm Hg with 0.7 (range 0-4) glaucoma medications. The mean IOP reduction after phaco was 3.0 (±2.6) mm Hg at postoperative month 6. After multivariate analysis, preop IOP (β=0.49 [0.41 - 0.58] P<0.0001), gonioscopy score (β=-0.17 [-0.24 - -0.09] P<0.0001), ACD (β=-0.88 [-1.64 - -0.14] P=0.02) and IOP/ACD ratio (β=0.45 [0.07 - 0.83] P=0.021) were associated with IOP reduction at 6 months. Preoperative predictors for IOP reduction after cataract surgery were preoperative IOP, ACD, gonioscopy score and IOP/ACD ratio. The IOP/ACD ratio and gonioscopy score can be easy parameters to obtain and may help clinicians to estimate the IOP reduction after phaco.

The Effect of Laser Trabeculoplasty on Posture-Induced Intraocular Pressure Changes in Patients with Open Angle Glaucoma

PubMed Central

Yang, Jee Myung; Sung, Mi Sun; Heo, Hwan; Park, Sang Woo

2016-01-01

Purpose To investigate the effect of argon laser trabeculoplasty (ALT) on posture-induced intraocular pressure (IOP) changes in patients with open angle glaucoma (OAG). Methods Thirty eyes of 30 consecutive patients with OAG who underwent ALT were prospectively analyzed. The IOP was measured using Icare PRO in the sitting position, supine position, and dependent lateral decubitus position (DLDP) before ALT and at 1 week, 1 month, 2 months, and 3 months after ALT. Results Compared to the baseline values, the IOP in each position was significantly decreased after ALT (all P < 0.001). During follow-up, the mean percentage of IOP reduction was similar in the sitting and supine positions, but was significantly lower in DLDP than in the sitting or supine positions (all P < 0.05). In terms of postural IOP changes, the IOP in the supine position and DLDP was significantly higher than that in the sitting position at the same time points during the follow-up period (all P < 0.001). The difference between the IOP in the supine position and DLDP during follow-up was significant (all P < 0.001). The extent of IOP differences between any positions did not show significant changes during the follow-up period (all P > 0.05). Conclusions ALT appears to be effective in lowering the IOP in various body positions, but the degree of this effect was significantly lower in DLDP. In addition, ALT seemed to have limited effects on posture-induced IOP changes. PMID:26807852

Real-time observation of X-ray diffraction patterns with the Lixiscope

NASA Technical Reports Server (NTRS)

Chung, D. Y.; Tsang, T.; Yin, L. I.; Anderson, J. R.

1981-01-01

The feasibility of the Lixiscope (Low Intensity X-ray Imaging Scope) is demonstrated for real-time observation of transmission Laue patterns. Making use of the high-gain capability of microchannel plate (MCP) visible-light image intensifier tubes, X-ray images are converted to visible-light images by a scintillator. Pb discs are taped to the center of the Lixiscope input face, and crystal samples are held on a goniometer stage with modeling clay. With a compact size to facilitate off axis viewing, and real-time viewing to allow instantaneous response, the Lixiscope may prove useful in dynamic studies of the effects of plastic flows, stresses, high pressures, and low temperatures.

Effects of central corneal thickness on measurement of intra-ocular pressure in keratoconus and post-keratoplasty.

PubMed

Patel, S; McLaughlin, J M

1999-05-01

To measure and compare central corneal thickness (CT) and intraocular pressure (IOP) in keratoconus and post-keratoplasty subjects and examine the CT-IOP relationship. 22 keratoconus (category I: six female sixteen male, average age 27.0 range 12-47) and 19 post-keratoplasty (category II: ten female nine male average age 34.6 range 16-54) patients without other anterior segment conditions were recruited. Only one, non-contact lens wearing, eye of the patient was included for analysis. Cornea was anaesthetised with non-preserved 0.4% Benoxinate Hydrochloride. Using a randomised approach, CT was measured using a standard ultrasonic pachymeter. IOP was then measured using a standard Goldmann tonometer. At all times the tonometrist remained unaware of the corneal thickness values. The mean (+/- s.d.) values for CT and IOP respectively in the two categories were: (I), 445 (45) mu and 9.8 (2.3) mmHg, (II), 564(44) microns and 15.8 (3.9) mmHg. Differences between I and II for both CT and IOP were significant (t-test, p = 0.01). Within each category, a significant correlation between CT and IOP was not found. Pooling all pairs of data (n = 41) a significant relationship between CT and IOP was detected (r = 0.635, p = 0.0001). The results confirm the hypothesis that an eye with a thicker cornea tends to present with a higher measured IOP. In the management of keratoconus and other corneal surgical procedures, changes in CT will contribute to any apparent changes in measured IOP.

Changes in the retrobulbar arterial circulation after decrease of the elevated intraocular pressure in men and women with primary open angle glaucoma.

PubMed

Marjanović, Ivan; Martinez, Antonio; Marjanović, Marija; Kontić, Djordje; Hentova-Senćanić, Paraskeva; Marković, Vujica; Bozić, Marija

2013-01-01

An altered perfusion of the optic nerve head has been proposed as a pathogenic factor of glaucoma. The aim of this study was to evaluate the changes of the hemodynamic parameters in the retrobulbar arterial circulation after decrease of the elevated intraocular pressure (IOP) in women and men with primary open angle glaucoma. The study included 60 patients (33 males and 27 females) older than 50 years, with diagnosed and treated primary open angle glaucoma (77 eyes of 39 patients had increased IOP, > 25 mm Hg).They were examined at the Clinic of Eye Diseases (complete ophthalmologic exam) and Clinic of Neurology, Clinical Center of Serbia, Belgrade, from December 2009 to December 2010. Imaging of hemodynamic parameters of three retrobulbar arterial vessels: ophthalmic, central retinal and posterior ciliary arteries with color Doppler was performed. Among women, hemodynamic arterial parameter of the peak-systolic velocity was increased in the central retinal artery and decreased in the ophthalmic artery and posterior ciliary arteries; end-diastolic velocity was increased in all three retrobulbar vascular levels; Pourcelot resistivity index was increased, but pulsatility index was decreased in all three vessels. Among men, peak-systolic velocity, end-diastolic velocity and pulsatility index were decreased in all three vessels; resistivity index was increased in the ophthalmic artery, but decreased in the central retinal artery and posterior ciliary arteries. There was a significant change of the ophthalmic artery pulsatility index in women, and the end-diastolic velocity of the ophthalmic artery in men. There was a difference of the retrobulbar arterial circulation between women and men with primary open angle glaucoma after decrease of the elevated intraocular pressure.The role of vascular factors in the supply of the optic disc neuroretinal rim is important.

Effect of Nocturnal Intermittent Peritoneal Dialysis on Intraocular Pressure and Anterior Segment Optical Coherence Tomography Parameters.

PubMed

Chong, Ka Lung; Samsudin, Amir; Keng, Tee Chau; Kamalden, Tengku Ain; Ramli, Norlina

2017-02-01

To evaluate the effect of nocturnal intermittent peritoneal dialysis (NIPD) on intraocular pressure (IOP) and anterior segment optical coherence tomography (ASOCT) parameters. Systemic changes associated with NIPD were also analyzed. Observational study. Nonglaucomatous patients on NIPD underwent systemic and ocular assessment including mean arterial pressure (MAP), body weight, serum osmolarity, visual acuity, IOP measurement, and ASOCT within 2 hours both before and after NIPD. The Zhongshan Angle Assessment Program (ZAAP) was used to measure ASOCT parameters including anterior chamber depth, anterior chamber width, anterior chamber area, anterior chamber volume, lens vault, angle opening distance, trabecular-iris space area, and angle recess area. T tests and Pearson correlation tests were performed with P<0.05 considered statistically significant. A total of 46 eyes from 46 patients were included in the analysis. There were statistically significant reductions in IOP (-1.8±0.6 mm Hg, P=0.003), MAP (-11.9±3.1 mm Hg, P<0.001), body weight (-0.7±2.8 kg, P<0.001), and serum osmolarity (-3.4±2.0 mOsm/L, P=0.002) after NIPD. All the ASOCT parameters did not have any statistically significant changes after NIPD. There were no statistically significant correlations between the changes in IOP, MAP, body weight, and serum osmolarity (all P>0.05). NIPD results in reductions in IOP, MAP, body weight, and serum osmolarity in nonglaucomatous patients.

Ethnic differences of intraocular pressure and central corneal thickness: the Singapore Epidemiology of Eye Diseases study.

PubMed

Chua, Jacqueline; Tham, Yih Chung; Liao, Jiemin; Zheng, Yingfeng; Aung, Tin; Wong, Tien Yin; Cheng, Ching-Yu

2014-10-01

To determine the ethnic differences in the distribution of intraocular pressure (IOP) and central corneal thickness (CCT) in a multi-ethnic Asian population by self-reported ethnicity and genetic ancestry. Population-based, cross-sectional study. A total of 10 033 adults (3353 Chinese, 3280 Malays, and 3400 Indians) aged >40 years. Participants underwent standardized systemic and ocular examinations and interviewer-administered questionnaires for risk factor assessment. The IOP readings were obtained by Goldmann applanation tonometry (Haag-Streit, Konig, Switzerland) before pupil dilation. The CCT was measured with ultrasound pachymetry. Genetic ancestry was derived using principal component (PC) analysis. Regression models were used to investigate the association of IOP and CCT with potential risk factors and genetic ancestry. Intraocular pressure and CCT. After excluding participants with a history of glaucoma surgery or medication, refractive surgery, corneal edema, or corneal dystrophy, IOP and CCT readings were available for 3251 Chinese, 3232 Malays, and 3317 Indians. The mean IOP readings in the Chinese, Malay, and Indian participants were 14.3±3.1, 15.3±3.7, and 15.8±2.9 mmHg, respectively (P < 0.001). The prevalence of participants with IOP ≥21 mmHg was 2.6% in Chinese, 6.2% in Malays, and 4% in Indians (P < 0.001). In the multivariate regression analysis, the Malay and Indian participants on average had 0.81 and 1.43 mmHg higher IOP levels, respectively, than Chinese (P < 0.001). The mean CCT reading was 552.3±33.4 μm in Chinese, 540.9±33.6 μm in Malays, and 540.4±33.6 μm in Indians (P < 0.001). The percentage of participants with CCT <555 μm was 52.8% in Chinese, 68.5% in Malays, and 66.2% in Indians (P < 0.001). The IOP and CCT levels are significantly correlated with genetic ancestry in our South East Asian population. Chinese have the thickest CCT but lowest IOP among the 3 major ethnic groups. In addition, there is a

Acting to gain information: Real-time reasoning meets real-time perception

NASA Technical Reports Server (NTRS)

Rosenschein, Stan

1994-01-01

Recent advances in intelligent reactive systems suggest new approaches to the problem of deriving task-relevant information from perceptual systems in real time. The author will describe work in progress aimed at coupling intelligent control mechanisms to real-time perception systems, with special emphasis on frame rate visual measurement systems. A model for integrated reasoning and perception will be discussed, and recent progress in applying these ideas to problems of sensor utilization for efficient recognition and tracking will be described.

Application of troposphere model from NWP and GNSS data into real-time precise positioning

NASA Astrophysics Data System (ADS)

Wilgan, Karina; Hadas, Tomasz; Kazmierski, Kamil; Rohm, Witold; Bosy, Jaroslaw

2016-04-01

The tropospheric delay empirical models are usually functions of meteorological parameters (temperature, pressure and humidity). The application of standard atmosphere parameters or global models, such as GPT (global pressure/temperature) model or UNB3 (University of New Brunswick, version 3) model, may not be sufficient, especially for positioning in non-standard weather conditions. The possible solution is to use regional troposphere models based on real-time or near-real time measurements. We implement a regional troposphere model into the PPP (Precise Point Positioning) software GNSS-WARP (Wroclaw Algorithms for Real-time Positioning) developed at Wroclaw University of Environmental and Life Sciences. The software is capable of processing static and kinematic multi-GNSS data in real-time and post-processing mode and takes advantage of final IGS (International GNSS Service) products as well as IGS RTS (Real-Time Service) products. A shortcoming of PPP technique is the time required for the solution to converge. One of the reasons is the high correlation among the estimated parameters: troposphere delay, receiver clock offset and receiver height. To efficiently decorrelate these parameters, a significant change in satellite geometry is required. Alternative solution is to introduce the external high-quality regional troposphere delay model to constrain troposphere estimates. The proposed model consists of zenith total delays (ZTD) and mapping functions calculated from meteorological parameters from Numerical Weather Prediction model WRF (Weather Research and Forecasting) and ZTDs from ground-based GNSS stations using the least-squares collocation software COMEDIE (Collocation of Meteorological Data for Interpretation and Estimation of Tropospheric Pathdelays) developed at ETH Zurich.

Diagnostic accuracy of intraocular pressure measurement for the detection of raised intracranial pressure: meta-analysis: a systematic review.

PubMed

Yavin, Daniel; Luu, Judy; James, Matthew T; Roberts, Derek J; Sutherland, Garnette R; Jette, Nathalie; Wiebe, Samuel

2014-09-01

Because clinical examination and imaging may be unreliable indicators of intracranial hypertension, intraocular pressure (IOP) measurement has been proposed as a noninvasive method of diagnosis. The authors conducted a systematic review and meta-analysis to determine the correlation between IOP and intracranial pressure (ICP) and the diagnostic accuracy of IOP measurement for detection of intracranial hypertension. The authors searched bibliographic databases (Ovid MEDLINE, Ovid EMBASE, and the Cochrane Central Register of Controlled Trials) from 1950 to March 2013, references of included studies, and conference abstracts for studies comparing IOP and invasive ICP measurement. Two independent reviewers screened abstracts, reviewed full-text articles, and extracted data. Correlation coefficients, sensitivity, specificity, and positive and negative likelihood ratios were calculated using DerSimonian and Laird methods and bivariate random effects models. The I(2) statistic was used as a measure of heterogeneity. Among 355 identified citations, 12 studies that enrolled 546 patients were included in the meta-analysis. The pooled correlation coefficient between IOP and ICP was 0.44 (95% CI 0.26-0.63, I(2) = 97.7%, p < 0.001). The summary sensitivity and specificity for IOP for diagnosing intracranial hypertension were 81% (95% CI 26%-98%, I(2) = 95.2%, p < 0.01) and 95% (95% CI 43%-100%, I(2) = 97.7%, p < 0.01), respectively. The summary positive and negative likelihood ratios were 14.8 (95% CI 0.5-417.7) and 0.2 (95% CI 0.02-1.7), respectively. When ICP and IOP measurements were taken within 1 hour of another, correlation between the measures improved. Although a modest aggregate correlation was found between IOP and ICP, the pooled diagnostic accuracy suggests that IOP measurement may be of clinical utility in the detection of intracranial hypertension. Given the significant heterogeneity between included studies, further investigation is required prior to the adoption

Real-time forecasting of the April 11, 2012 Sumatra tsunami

USGS Publications Warehouse

Wang, Dailin; Becker, Nathan C.; Walsh, David; Fryer, Gerard J.; Weinstein, Stuart A.; McCreery, Charles S.; ,

2012-01-01

The April 11, 2012, magnitude 8.6 earthquake off the northern coast of Sumatra generated a tsunami that was recorded at sea-level stations as far as 4800 km from the epicenter and at four ocean bottom pressure sensors (DARTs) in the Indian Ocean. The governments of India, Indonesia, Sri Lanka, Thailand, and Maldives issued tsunami warnings for their coastlines. The United States' Pacific Tsunami Warning Center (PTWC) issued an Indian Ocean-wide Tsunami Watch Bulletin in its role as an Interim Service Provider for the region. Using an experimental real-time tsunami forecast model (RIFT), PTWC produced a series of tsunami forecasts during the event that were based on rapidly derived earthquake parameters, including initial location and Mwp magnitude estimates and the W-phase centroid moment tensor solutions (W-phase CMTs) obtained at PTWC and at the U. S. Geological Survey (USGS). We discuss the real-time forecast methodology and how successive, real-time tsunami forecasts using the latest W-phase CMT solutions improved the accuracy of the forecast.

Perilimbal sclera mechanical properties: Impact on intraocular pressure in porcine eyes

PubMed Central

Man, Xiaofei; Arroyo, Elizabeth; Dunbar, Martha; Reed, David M.; Shah, Neil; Kagemann, Larry; Kim, Wonsuk; Moroi, Sayoko E.

2018-01-01

There is extensive knowledge on the relationship of posterior scleral biomechanics and intraocular pressure (IOP) load on glaucomatous optic neuropathy; however, the role for biomechanical influence of the perilimbal scleral tissue on the aqueous humor drainage pathway, including the distal venous outflow system, and IOP regulation is not fully understood. The purpose of this work is to study the outflow characteristics of perfused porcine eyes relative to the biomechanical properties of the perilimbal sclera, the posterior sclera and the cornea. Enucleated porcine eyes from eleven different animals were perfused with surrogate aqueous at two fixed flow rates while monitoring their IOP. After perfusion, mechanical stress-strain and relaxation tests were conducted on specimens of perilimbal sclera, posterior sclera, and cornea from the same perfused eyes. Statistical analysis of the data demonstrated a strong correlation between increased tangent modulus of the perilimbal sclera tissues and increased perfusion IOP (R2 = 0.74, p = 0.0006 at lower flow rate and R2 = 0.71, p = 0.0011 at higher flow rate). In contrast, there were no significant correlations between IOP and the tangent modulus of the other tissues (Posterior sclera: R2 = 0.17 at lower flow rate and R2 = 0.30 at higher flow rate; cornea: R2 = 0.02 at lower flow rate and R2<0.01 at higher flow rate) nor the viscoelastic properties of any tissue (R2 ≤ 0.08 in all cases). Additionally, the correlation occurred for IOP and not net outflow facility (R2 ≤ 0.12 in all cases). These results provide new evidence that IOP in perfused porcine eyes is strongly influenced by the tangent modulus, sometimes called the tissue stiffness, of the most anterior portion of the sclera, i.e. the limbus. PMID:29718942

Deformable Surface Accommodating Intraocular Lens: Second Generation Prototype Design Methodology and Testing.

PubMed

McCafferty, Sean J; Schwiegerling, Jim T

2015-04-01

Present an analysis methodology for developing and evaluating accommodating intraocular lenses incorporating a deformable interface. The next generation design of extruded gel interface intraocular lens is presented. A prototype based upon similar previously in vivo proven design was tested with measurements of actuation force, lens power, interface contour, optical transfer function, and visual Strehl ratio. Prototype verified mathematical models were used to optimize optical and mechanical design parameters to maximize the image quality and minimize the required force to accommodate. The prototype lens produced adequate image quality with the available physiologic accommodating force. The iterative mathematical modeling based upon the prototype yielded maximized optical and mechanical performance through maximum allowable gel thickness to extrusion diameter ratio, maximum feasible refractive index change at the interface, and minimum gel material properties in Poisson's ratio and Young's modulus. The design prototype performed well. It operated within the physiologic constraints of the human eye including the force available for full accommodative amplitude using the eye's natural focusing feedback, while maintaining image quality in the space available. The parameters that optimized optical and mechanical performance were delineated as those, which minimize both asphericity and actuation pressure. The design parameters outlined herein can be used as a template to maximize the performance of a deformable interface intraocular lens. The article combines a multidisciplinary basic science approach from biomechanics, optical science, and ophthalmology to optimize an intraocular lens design suitable for preliminary animal trials.

A real-time architecture for time-aware agents.

PubMed

Prouskas, Konstantinos-Vassileios; Pitt, Jeremy V

2004-06-01

This paper describes the specification and implementation of a new three-layer time-aware agent architecture. This architecture is designed for applications and environments where societies of humans and agents play equally active roles, but interact and operate in completely different time frames. The architecture consists of three layers: the April real-time run-time (ART) layer, the time aware layer (TAL), and the application agents layer (AAL). The ART layer forms the underlying real-time agent platform. An original online, real-time, dynamic priority-based scheduling algorithm is described for scheduling the computation time of agent processes, and it is shown that the algorithm's O(n) complexity and scalable performance are sufficient for application in real-time domains. The TAL layer forms an abstraction layer through which human and agent interactions are temporally unified, that is, handled in a common way irrespective of their temporal representation and scale. A novel O(n2) interaction scheduling algorithm is described for predicting and guaranteeing interactions' initiation and completion times. The time-aware predicting component of a workflow management system is also presented as an instance of the AAL layer. The described time-aware architecture addresses two key challenges in enabling agents to be effectively configured and applied in environments where humans and agents play equally active roles. It provides flexibility and adaptability in its real-time mechanisms while placing them under direct agent control, and it temporally unifies human and agent interactions.

Real Time Conference 2014 Overview

NASA Astrophysics Data System (ADS)

Nomachi, Masaharu

2015-06-01

This article presents an overview of the 19th Real Time Conference held last May 26-30, 2014, at the Nara Prefectural New Public Hall, Nara, Japan, organized by the Research Center for Nuclear Physics of the Osaka University. The program included many invited talks and oral sessions offering an extensive overview on the following topics: real-time system architectures, intelligent signal processing, fast data transfer links and networks, trigger systems, data acquisition, processing-farms, control, monitoring and test systems, emerging real-time technologies, new standards, real-time safety and security, and some feedback on experiences. In parallel to the oral and poster presentations, industrial exhibits by companies, workshops and short courses also ran through the week.

Real-time flutter identification

NASA Technical Reports Server (NTRS)

Roy, R.; Walker, R.

1985-01-01

The techniques and a FORTRAN 77 MOdal Parameter IDentification (MOPID) computer program developed for identification of the frequencies and damping ratios of multiple flutter modes in real time are documented. Physically meaningful model parameterization was combined with state of the art recursive identification techniques and applied to the problem of real time flutter mode monitoring. The performance of the algorithm in terms of convergence speed and parameter estimation error is demonstrated for several simulated data cases, and the results of actual flight data analysis from two different vehicles are presented. It is indicated that the algorithm is capable of real time monitoring of aircraft flutter characteristics with a high degree of reliability.

HEVC real-time decoding

NASA Astrophysics Data System (ADS)

Bross, Benjamin; Alvarez-Mesa, Mauricio; George, Valeri; Chi, Chi Ching; Mayer, Tobias; Juurlink, Ben; Schierl, Thomas

2013-09-01

The new High Efficiency Video Coding Standard (HEVC) was finalized in January 2013. Compared to its predecessor H.264 / MPEG4-AVC, this new international standard is able to reduce the bitrate by 50% for the same subjective video quality. This paper investigates decoder optimizations that are needed to achieve HEVC real-time software decoding on a mobile processor. It is shown that HEVC real-time decoding up to high definition video is feasible using instruction extensions of the processor while decoding 4K ultra high definition video in real-time requires additional parallel processing. For parallel processing, a picture-level parallel approach has been chosen because it is generic and does not require bitstreams with special indication.

Acoustic Performance of a Real-Time Three-Dimensional Sound-Reproduction System

NASA Technical Reports Server (NTRS)

Faller, Kenneth J., II; Rizzi, Stephen A.; Aumann, Aric R.

2013-01-01

The Exterior Effects Room (EER) is a 39-seat auditorium at the NASA Langley Research Center and was built to support psychoacoustic studies of aircraft community noise. The EER has a real-time simulation environment which includes a three-dimensional sound-reproduction system. This system requires real-time application of equalization filters to compensate for spectral coloration of the sound reproduction due to installation and room effects. This paper describes the efforts taken to develop the equalization filters for use in the real-time sound-reproduction system and the subsequent analysis of the system s acoustic performance. The acoustic performance of the compensated and uncompensated sound-reproduction system is assessed for its crossover performance, its performance under stationary and dynamic conditions, the maximum spatialized sound pressure level it can produce from a single virtual source, and for the spatial uniformity of a generated sound field. Additionally, application examples are given to illustrate the compensated sound-reproduction system performance using recorded aircraft flyovers

Intraocular cysts of toxoplasma gondii in patients with necrotizing retinitis following periocular/intraocular triamcinolone injection.

PubMed

Nijhawan, Raje; Bansal, Reema; Gupta, Nalini; Beke, Nikhil; Kulkarni, Pandurang; Gupta, Amod

2013-10-01

To report the detection of Toxoplasma gondii cysts in intraocular aspirates of patients with necrotizing retinitis following periocular/intraocular corticosteroid injection. Case report. Two patients (2 eyes) with widespread necrotizing retinitis in a steroid-exposed eye posed a diagnostic challenge and underwent pars plana vitrectomy (PPV). Intraocular samples (vitreous fluid, retinal tissue, and subretinal aspirate in case 1, and vitreous fluid in case 2) were subjected to cytological examination. The subretinal aspirate (case 1) revealed encysted bradyzoites of Toxoplasma gondii. Vitreous fluid (case 2) tested positive for anti-toxoplasma antibodies and the smear showed encysted forms of Toxoplasma gondii on cytology. CONCLUSION. Toxoplasma gondii cysts were detected in eyes with necrotizing retinitis that developed secondary to injudicious use of corticosteroids.

Reduction of enhanced rabbit intraocular pressure by instillation of pyroglutamic acid eye drops.

PubMed

Ito, Yoshimasa; Nagai, Noriaki; Okamoto, Norio; Shimomura, Yoshikazu; Nakanishi, Kunio; Tanaka, Ryuichiro

2013-01-01

L-Pyroglutamic acid (PGA) is an endogenous molecule derived from l-glutamate. We demonstrate the effects of PGA on intraocular pressure (IOP) in experimentally induced ocular hypertension in rabbits. In the in vitro and in vivo transcorneal penetration studies, the PGA solution (PGA in saline) did not penetrate the rabbit cornea. On the other hand, the penetration of PGA was improved by the addition of zinc chloride and 2-hydroxypropyl-β-cyclodextrin (HPCD), and PGA penetration was enhanced with increasing HPCD concentration. Therefore, PGA solutions containing 0.5% zinc chloride and 5% or 10% HPCD (PGA/HPCD(5% or 10%) eye drops) were used to investigate the effects for IOP in this study. An elevation in IOP was induced by the rapid infusion of 5% glucose solution (15 mL/kg of body weight) through the marginal ear vein or maintaining under dark phase for 5 h. In the both models, the induced elevation in IOP was prevented by the instillation of PGA/HPCD eye drops, and the IOP-reducing effect enhanced with increasing HPCD concentration in the drops. Nitric oxide (NO) levels elevated in the aqueous humor following the infusion of 5% glucose solution, and this increase was also suppressed by the instillation of PGA/HPCD eye drops. In conclusion, the present study demonstrates that the instillation of PGA/HPCD eye drops has an IOP-reducing effect in rabbits with experimentally induced ocular hypertension, probably as a result of the suppression of NO production.

The Effect of Dehydration and Fasting on Corneal Biomechanical Properties and Intraocular Pressure.

PubMed

Oltulu, Refik; Satirtav, Gunhal; Ersan, Ismail; Soylu, Erkan; Okka, Mehmet; Zengin, Nazmi

2016-11-01

To evaluate the changes in corneal biomechanical properties and intraocular pressure (IOP) during fasting period in healthy subjects. Seventy-two eyes of 72 fasting subjects (study group), and 62 eyes of 62 nonfasting subjects (control group) were enrolled in this prospective study undertaken at a single university hospital. All subjects underwent complete ophthalmologic examination including ocular biomechanical evaluation with ocular response analyzer. Ocular response analyzer measurement was performed on the right eyes of the subjects between 5.00 and 6.00 PM after approximately 14 hr of fasting for the study group and after a nonfasting period for the control group. The corneal hysteresis, corneal resistance factor, mean corneal compensated IOP (IOPcc), and Goldmann-correlated IOP (IOPg) values were measured with a patented dynamic bidirectional applanation process. Goldmann-correlated IOP and IOPcc measurements in the study group and the control group were found as 13.8±2.8 mm Hg, 14.6±2.6 mm Hg and 16.3±2.2 mm Hg, 15.7±2.4 mm Hg, respectively. There was statistically significant difference within the two groups in IOPg and IOPcc (P<0.001). In addition, corneal hysteresis and corneal resistance factor significantly decreased in study group compared with control group (P<0.001, P=0.012, respectively). Prolonged fasting causes a significant decrease in IOPg, IOPcc, corneal hysteresis, and corneal resistance factor in healthy subjects, altering the biomechanical properties of the cornea.

EFFECTS OF TOPICAL CORTICOSTEROID ADMINISTRATION ON INTRAOCULAR PRESSURE IN NORMAL AND GLAUCOMATOUS CATS

PubMed Central

Gosling, Allyson A; Kiland, Julie A; Rutkowski, Lauren E; Hoefs, Adam; Ellinwood, N Matthew; McLellan, Gillian J

2016-01-01

Objective to determine the effect of topical corticosteroid (CCS) therapy on intraocular pressure (IOP) in normal cats and cats with primary feline congenital glaucoma (FCG). Animals studied 5 normal and 11 FCG cats were studied in 2 cohorts. Procedures IOP was measured by a single, masked observer, once daily 3–5 days/week throughout the course of CCS treatment and for up to 11 days after treatment discontinuation. One eye per cat was randomly assigned for treatment twice daily with CCS; Balanced salt solution (BSS) applied to the contralateral eye, served as a control. Differences between eyes and between weeks of the study period were calculated for each cat. A positive response to CCS was defined as a consistent >15% or >25% higher IOP in the treated relative to control eye in normal and FCG cats, respectively. Results 8/11 FCG cats responded to topical CCS after 1–5 weeks of treatment with an increase in IOP relative to the untreated eye (maximum IOP discrepancy of 56 mmHg). 2/5 normal cats responded to topical CCS with appreciable but clinically unimportant increase in IOP in the treated eye (maximum IOP discrepancy of 6.4 mmHg). Conclusions our data indicate that the incidence of steroid induced IOP elevation in cats is lower than previously published feline studies suggest. Cats with pre-existing compromise in aqueous humor outflow may show a greater, clinically relevant response to topical CCS than normal cats. PMID:26876736

Ocular perfusion pressure control during pars plana vitrectomy: testing a novel device.

PubMed

Rossi, Tommaso; Querzoli, Giorgio; Gelso, Aldo; Angelini, Giampiero; Rossi, Alessandro; Corazza, Paolo; Landi, Laura; Telani, Serena; Ripandelli, Guido

2017-12-01

To study the efficacy of a novel device intended to control infusion pressure based on mean ocular perfusion pressure (MOPP) during pars plana vitrectomy (PPV). An arm blood pressure cuff connected to a vitrectomy machine calculated mean arterial pressure (MAP), while a pressure sensor close to the infusion trocar measured intraocular pressure (IOP). MOPP was calculated in real time in 36 consecutive patients undergoing PPV, who were divided into two groups. The device lowered IOP every time that calculated MOPP fell below 30 mmHg in the Control ON group (18 patients), while no action was taken in the Control OFF group (18 patients). Baseline IOP and blood pressure were similar between groups. The Control ON group had significantly lower average intraoperative IOP (30.5 ± 2.1 vs. 35.9 ± 6.9 mmHg; p = 0.002) and higher MOPP (56.4 ± 5.9 vs. 49.7 ± 6.1 mmHg) than the Control OFF group. The Control ON group also spent less time at MOPP < 10 mmHg and < 30 mmHg: 0 vs. 3.40 ± 2.38 min (p < 0.001) and 9.91 ± 7.15 vs. 16.13 ± 8.12 min (p = 0.02), respectively. The MOPP control device effectively maintained lower IOP and higher MOPP throughout surgery. It also helped avoid dangerous IOP peaks and MOPP dips, allowing patients to spend less time at MOPP of < 10 and < 30 mmHg.

Scleral and intraocular amoebic dissemination in Acanthamoeba keratitis.

PubMed

Arnalich-Montiel, Francisco; Jaumandreu, Laia; Leal, Marina; Valladares, Basilio; Lorenzo-Morales, Jacob

2013-12-01

To review an Acanthamoeba keratitis case series for the documented extracorneal spread of the amoeba. A retrospective review of an observational case series from a single institution. Three patients with 4 instances of microbiologically confirmed extracorneal amoebic spread were identified. Patient 1 had nodular scleritis after undergoing penetrating keratoplasty and was treated successfully with double freeze-thaw cryotherapy; patient 2 had intraocular dissemination of the amoeba detected in a retrocorneal membrane; and patient 3 had, after undergoing tectonic keratoplasty, intraocular dissemination of the amoeba that was treated successfully with intraocular and systemic voriconazole and, afterwards, a nodular scleritis treated with double freeze-thaw cryotherapy and a large-diameter corneal graft to treat corneal recurrence. Acanthamoeba can migrate to the sclera or to the intraocular tissues in some instances, such as in long-standing disease or in penetrating keratoplasty. A prompt biopsy for microbiological analysis and early treatment are required, if this is suspected. Voriconazole can be effective for intraocular invasion when used orally and intraocularly. Scleral involvement might require a surgical approach with double freeze-thaw cryotherapy to treat the localized disease.

Intraocular inflammation in autoimmune diseases.

PubMed

Pras, Eran; Neumann, Ron; Zandman-Goddard, Gisele; Levy, Yair; Assia, Ehud I; Shoenfeld, Yehuda; Langevitz, Pnina

2004-12-01

The uveal tract represents the vascular organ of the eye. In addition to providing most of the blood supply to the intraocular structures, it acts as a conduit for immune cells, particularly lymphocytes, to enter the eye. Consequently, the uveal tract is represented in many intraocular inflammatory processes. Uveitis is probably a misnomer unless antigens within the uvea are the direct targets of the inflammatory process. A better term of the condition is "intraocular inflammation" (IOI). To review the presence of IOI in autoimmune diseases, the immunopathogenic mechanisms leading to disease, and treatment. We reviewed the English medical literature by using MEDLINE (1984-2003) employing the terms "uveitis," "intraocular inflammation," and "autoimmune diseases." An underlying autoimmune disease was identified in up to 40% of patients with IOI, and included spondyloarthropathies, Behcets disease, sarcoidosis, juvenile chronic arthritis, Vogt-Koyanagi-Harada syndrome (an inflammatory syndrome including uveitis with dermatologic and neurologic manifestations), immune recovery syndrome, and uveitis with tubulointerstitial disease. The immunopathogenesis of IOI involves enhanced T-cell response. Recently, guidelines for the use of immunosuppressive drugs for inflammatory eye disease were established and include: corticosteroids, azathioprine, methotrexate, mycophenolate mofetil, cyclosporine, tacrolimus, cyclophosphamide, and chlorambucil. New therapies with limited experience include the tumor necrosis factor alpha inhibitors, interferon alfa, monoclonal antibodies against lymphocyte surface antigens, intravenous immunoglobulin (IVIG), and the intraocular delivery of immunosuppressive agents. An underlying autoimmune disease was identified in up to 40% of patients with IOI. Immunosuppressive drugs, biologic agents, and IVIG are employed for the treatment of IOI in autoimmune diseases.

Intraocular pressure spike after YAG iridotomy in patients with pigment dispersion.

PubMed

Birt, Catherine M

2004-04-01

The role of laser peripheral iridotomy to break a suspected reverse pupil block in the long-term control of pigment dispersion is promising, but the usefulness of this procedure has not been completely established. The author examined whether patients with pigment dispersion are at higher risk for an intraocular pressure (IOP) spike after laser peripheral iridotomy due to possible compromise of trabecular meshwork function, compared with patients undergoing prophylactic peripheral iridotomy for an occludable angle. Data were collected prospectively on the first eye of 87 patients with occludable angles and 13 patients with pigment dispersion treated with peripheral laser iridotomy between November 1995 and October 1996 at the glaucoma service of a university-affiliated hospital in Toronto. All patients received one drop of 0.5% apraclonidine before the procedure. IOP was measured before and 1 and 24 hours after the procedure. There was no difference between the two groups in the distribution of right vs. left eyes, sex, race, the mean total energy required to produce a patent iridotomy, the mean number of medications used or the mean IOP before the procedure. The patients with pigment dispersion were significantly younger than those with occludable angles (mean age [and standard deviation (SD)] 40.5 [9.45] years vs. 66.4 [10.78] years) (p < 0.001). There was no difference between the two groups in mean IOP at 1 hour or at 24 hours. Twenty-nine patients (33%) in the occludable angle group and seven (54%) in the pigment dispersion group had an IOP spike greater than 2 mm Hg after the procedure (p = 0.001). Among these patients, the mean IOP (36.4 [SD 10.83] mm Hg vs. 30.3 [SD 7.04] mm Hg, p = 0.05) and the mean rise in IOP (14.0 [SD 10.63] mm Hg vs. 8.7 [SD 4.73] mm Hg, p = 0.04) were significantly higher in those with pigment dispersion than in those with occludable angles. Among the patients who used antiglaucoma medications before the procedure or had a prelaser

Real-time PCR in virology.

PubMed

Mackay, Ian M; Arden, Katherine E; Nitsche, Andreas

2002-03-15

The use of the polymerase chain reaction (PCR) in molecular diagnostics has increased to the point where it is now accepted as the gold standard for detecting nucleic acids from a number of origins and it has become an essential tool in the research laboratory. Real-time PCR has engendered wider acceptance of the PCR due to its improved rapidity, sensitivity, reproducibility and the reduced risk of carry-over contamination. There are currently five main chemistries used for the detection of PCR product during real-time PCR. These are the DNA binding fluorophores, the 5' endonuclease, adjacent linear and hairpin oligoprobes and the self-fluorescing amplicons, which are described in detail. We also discuss factors that have restricted the development of multiplex real-time PCR as well as the role of real-time PCR in quantitating nucleic acids. Both amplification hardware and the fluorogenic detection chemistries have evolved rapidly as the understanding of real-time PCR has developed and this review aims to update the scientist on the current state of the art. We describe the background, advantages and limitations of real-time PCR and we review the literature as it applies to virus detection in the routine and research laboratory in order to focus on one of the many areas in which the application of real-time PCR has provided significant methodological benefits and improved patient outcomes. However, the technology discussed has been applied to other areas of microbiology as well as studies of gene expression and genetic disease.

A Real-Time Method for Estimating Viscous Forebody Drag Coefficients

NASA Technical Reports Server (NTRS)

Whitmore, Stephen A.; Hurtado, Marco; Rivera, Jose; Naughton, Jonathan W.

2000-01-01

This paper develops a real-time method based on the law of the wake for estimating forebody skin-friction coefficients. The incompressible law-of-the-wake equations are numerically integrated across the boundary layer depth to develop an engineering model that relates longitudinally averaged skin-friction coefficients to local boundary layer thickness. Solutions applicable to smooth surfaces with pressure gradients and rough surfaces with negligible pressure gradients are presented. Model accuracy is evaluated by comparing model predictions with previously measured flight data. This integral law procedure is beneficial in that skin-friction coefficients can be indirectly evaluated in real-time using a single boundary layer height measurement. In this concept a reference pitot probe is inserted into the flow, well above the anticipated maximum thickness of the local boundary layer. Another probe is servomechanism-driven and floats within the boundary layer. A controller regulates the position of the floating probe. The measured servomechanism position of this second probe provides an indirect measurement of both local and longitudinally averaged skin friction. Simulation results showing the performance of the control law for a noisy boundary layer are then presented.

Performances of the New Real Time Tsunami Detection Algorithm applied to tide gauges data

NASA Astrophysics Data System (ADS)

Chierici, F.; Embriaco, D.; Morucci, S.

2017-12-01

Real-time tsunami detection algorithms play a key role in any Tsunami Early Warning System. We have developed a new algorithm for tsunami detection (TDA) based on the real-time tide removal and real-time band-pass filtering of seabed pressure time series acquired by Bottom Pressure Recorders. The TDA algorithm greatly increases the tsunami detection probability, shortens the detection delay and enhances detection reliability with respect to the most widely used tsunami detection algorithm, while containing the computational cost. The algorithm is designed to be used also in autonomous early warning systems with a set of input parameters and procedures which can be reconfigured in real time. We have also developed a methodology based on Monte Carlo simulations to test the tsunami detection algorithms. The algorithm performance is estimated by defining and evaluating statistical parameters, namely the detection probability, the detection delay, which are functions of the tsunami amplitude and wavelength, and the occurring rate of false alarms. In this work we present the performance of the TDA algorithm applied to tide gauge data. We have adapted the new tsunami detection algorithm and the Monte Carlo test methodology to tide gauges. Sea level data acquired by coastal tide gauges in different locations and environmental conditions have been used in order to consider real working scenarios in the test. We also present an application of the algorithm to the tsunami event generated by Tohoku earthquake on March 11th 2011, using data recorded by several tide gauges scattered all over the Pacific area.

Downregulation of Glutamine Synthetase via GLAST Suppression Induces Retinal Axonal Swelling in a Rat Ex Vivo Hydrostatic Pressure Model

PubMed Central

Yoshitomi, Takeshi; Zorumski, Charles F.; Izumi, Yukitoshi

2011-01-01

Purpose. High levels of glutamate can be toxic to retinal GCs. Thus, effective buffering of extracellular glutamate is important in preserving retinal structure and function. GLAST, a major glutamate transporter in the retina, and glutamine synthetase (GS) regulate extracellular glutamate accumulation and prevent excitotoxicity. This study was an examination of changes in function and expression of GLAST and GS in ex vivo rat retinas exposed to acute increases in ambient pressure. Methods. Ex vivo rat retinas were exposed to elevated hydrostatic pressure for 24 hours. The expression of GLAST and GS were examined using immunochemistry and real-time PCR analysis. Also examined were the effects of (2S,3S)-3-[3-[4-(trifluoromethyl) benzoylamino] benzyloxy] aspartate (TFB-TBOA), an inhibitor of glutamate transporters, and l-methionine-S-sulfoximine (MSO), an inhibitor of GS. Results. In this acute model, Western blot and real-time RT-PCR analyses revealed that substantially (75 mm Hg), but not moderately (35 mm Hg), elevated pressure depressed GLAST expression, diminished GS activity, and induced axonal swelling between the GC layer and the inner limiting membrane. However, at the moderately elevated pressure (35 mm Hg), administration of either TFB-TBOA or MSO also induced axonal swelling and excitotoxic neuronal damage. MSO did not depress GLAST expression but TFB-TBOA significantly suppressed GS, suggesting that downregulation of GS during pressure loading may result from impaired GLAST expression. Conclusions. The retina is at risk during acute intraocular pressure elevation due to downregulation of GS activity resulting from depressed GLAST expression. PMID:21775659

Downregulation of glutamine synthetase via GLAST suppression induces retinal axonal swelling in a rat ex vivo hydrostatic pressure model.

PubMed

Ishikawa, Makoto; Yoshitomi, Takeshi; Zorumski, Charles F; Izumi, Yukitoshi

2011-08-22

PURPOSE. High levels of glutamate can be toxic to retinal GCs. Thus, effective buffering of extracellular glutamate is important in preserving retinal structure and function. GLAST, a major glutamate transporter in the retina, and glutamine synthetase (GS) regulate extracellular glutamate accumulation and prevent excitotoxicity. This study was an examination of changes in function and expression of GLAST and GS in ex vivo rat retinas exposed to acute increases in ambient pressure. METHODS. Ex vivo rat retinas were exposed to elevated hydrostatic pressure for 24 hours. The expression of GLAST and GS were examined using immunochemistry and real-time PCR analysis. Also examined were the effects of (2S,3S)-3-[3-[4-(trifluoromethyl) benzoylamino] benzyloxy] aspartate (TFB-TBOA), an inhibitor of glutamate transporters, and l-methionine-S-sulfoximine (MSO), an inhibitor of GS. RESULTS. In this acute model, Western blot and real-time RT-PCR analyses revealed that substantially (75 mm Hg), but not moderately (35 mm Hg), elevated pressure depressed GLAST expression, diminished GS activity, and induced axonal swelling between the GC layer and the inner limiting membrane. However, at the moderately elevated pressure (35 mm Hg), administration of either TFB-TBOA or MSO also induced axonal swelling and excitotoxic neuronal damage. MSO did not depress GLAST expression but TFB-TBOA significantly suppressed GS, suggesting that downregulation of GS during pressure loading may result from impaired GLAST expression. CONCLUSIONS. The retina is at risk during acute intraocular pressure elevation due to downregulation of GS activity resulting from depressed GLAST expression.

Intraocular extramedullary plasmacytoma in a cat.

PubMed

Michau, Tammy Miller; Proulx, David R; Rushton, Steven D; Olivry, Thierry; Dunston, Stanley M; Gilger, Brian C; Davidson, Michael G

2003-06-01

An 8-year-old, castrated male Domestic Short-haired cat was referred for evaluation of a possible intraocular neoplasm following previous ocular trauma. The eye was blind, and uveitis and an iridal mass were noted on examination. An enucleation was performed and the mandibular lymph node excised. Histopathologic examination revealed neoplastic proliferation of plasma cells in the iris and lymph node. No other evidence of disseminated disease was detected. This is the first case reported of an intraocular extramedullary plasmacytoma in the cat. The variation in clinical manifestations and potential association with multiple myeloma are not known at this time. Disseminated metastasis from a primary plasmacytoma of the uveal tract could also involve the bone marrow and be indistinguishable from multiple myeloma. Early enucleation, as in trauma-associated sarcomas, may be indicated to prevent metastasis. Periodic systemic evaluation for evidence of multiple myeloma should be performed.

Language at Three Timescales: The Role of Real-Time Processes in Language Development and Evolution.

PubMed

McMurray, Bob

2016-04-01

Evolutionary developmental systems (evo-devo) theory stresses that selection pressures operate on entire developmental systems rather than just genes. This study extends this approach to language evolution, arguing that selection pressure may operate on two quasi-independent timescales. First, children clearly must acquire language successfully (as acknowledged in traditional evo-devo accounts) and evolution must equip them with the tools to do so. Second, while this is developing, they must also communicate with others in the moment using partially developed knowledge. These pressures may require different solutions, and their combination may underlie the evolution of complex mechanisms for language development and processing. I present two case studies to illustrate how the demands of both real-time communication and language acquisition may be subtly different (and interact). The first case study examines infant-directed speech (IDS). A recent view is that IDS underwent cultural to statistical learning mechanisms that infants use to acquire the speech categories of their language. However, recent data suggest is it may not have evolved to enhance development, but rather to serve a more real-time communicative function. The second case study examines the argument for seemingly specialized mechanisms for learning word meanings (e.g., fast-mapping). Both behavioral and computational work suggest that learning may be much slower and served by general-purpose mechanisms like associative learning. Fast-mapping, then, may be a real-time process meant to serve immediate communication, not learning, by augmenting incomplete vocabulary knowledge with constraints from the current context. Together, these studies suggest that evolutionary accounts consider selection pressure arising from both real-time communicative demands and from the need for accurate language development. Copyright © 2016 Cognitive Science Society, Inc.

MARTe: A Multiplatform Real-Time Framework

NASA Astrophysics Data System (ADS)

Neto, André C.; Sartori, Filippo; Piccolo, Fabio; Vitelli, Riccardo; De Tommasi, Gianmaria; Zabeo, Luca; Barbalace, Antonio; Fernandes, Horacio; Valcarcel, Daniel F.; Batista, Antonio J. N.

2010-04-01

Development of real-time applications is usually associated with nonportable code targeted at specific real-time operating systems. The boundary between hardware drivers, system services, and user code is commonly not well defined, making the development in the target host significantly difficult. The Multithreaded Application Real-Time executor (MARTe) is a framework built over a multiplatform library that allows the execution of the same code in different operating systems. The framework provides the high-level interfaces with hardware, external configuration programs, and user interfaces, assuring at the same time hard real-time performances. End-users of the framework are required to define and implement algorithms inside a well-defined block of software, named Generic Application Module (GAM), that is executed by the real-time scheduler. Each GAM is reconfigurable with a set of predefined configuration meta-parameters and interchanges information using a set of data pipes that are provided as inputs and required as output. Using these connections, different GAMs can be chained either in series or parallel. GAMs can be developed and debugged in a non-real-time system and, only once the robustness of the code and correctness of the algorithm are verified, deployed to the real-time system. The software also supplies a large set of utilities that greatly ease the interaction and debugging of a running system. Among the most useful are a highly efficient real-time logger, HTTP introspection of real-time objects, and HTTP remote configuration. MARTe is currently being used to successfully drive the plasma vertical stabilization controller on the largest magnetic confinement fusion device in the world, with a control loop cycle of 50 ?s and a jitter under 1 ?s. In this particular project, MARTe is used with the Real-Time Application Interface (RTAI)/Linux operating system exploiting the new ?86 multicore processors technology.

GNSS global real-time augmentation positioning: Real-time precise satellite clock estimation, prototype system construction and performance analysis

NASA Astrophysics Data System (ADS)

Chen, Liang; Zhao, Qile; Hu, Zhigang; Jiang, Xinyuan; Geng, Changjiang; Ge, Maorong; Shi, Chuang

2018-01-01

Lots of ambiguities in un-differenced (UD) model lead to lower calculation efficiency, which isn't appropriate for the high-frequency real-time GNSS clock estimation, like 1 Hz. Mixed differenced model fusing UD pseudo-range and epoch-differenced (ED) phase observations has been introduced into real-time clock estimation. In this contribution, we extend the mixed differenced model for realizing multi-GNSS real-time clock high-frequency updating and a rigorous comparison and analysis on same conditions are performed to achieve the best real-time clock estimation performance taking the efficiency, accuracy, consistency and reliability into consideration. Based on the multi-GNSS real-time data streams provided by multi-GNSS Experiment (MGEX) and Wuhan University, GPS + BeiDou + Galileo global real-time augmentation positioning prototype system is designed and constructed, including real-time precise orbit determination, real-time precise clock estimation, real-time Precise Point Positioning (RT-PPP) and real-time Standard Point Positioning (RT-SPP). The statistical analysis of the 6 h-predicted real-time orbits shows that the root mean square (RMS) in radial direction is about 1-5 cm for GPS, Beidou MEO and Galileo satellites and about 10 cm for Beidou GEO and IGSO satellites. Using the mixed differenced estimation model, the prototype system can realize high-efficient real-time satellite absolute clock estimation with no constant clock-bias and can be used for high-frequency augmentation message updating (such as 1 Hz). The real-time augmentation message signal-in-space ranging error (SISRE), a comprehensive accuracy of orbit and clock and effecting the users' actual positioning performance, is introduced to evaluate and analyze the performance of GPS + BeiDou + Galileo global real-time augmentation positioning system. The statistical analysis of real-time augmentation message SISRE is about 4-7 cm for GPS, whlile 10 cm for Beidou IGSO/MEO, Galileo and about 30 cm

Increased expression of the WNT antagonist sFRP-1 in glaucoma elevates intraocular pressure

PubMed Central

Wang, Wan-Heng; McNatt, Loretta G.; Pang, Iok-Hou; Millar, J. Cameron; Hellberg, Peggy E.; Hellberg, Mark H.; Steely, H. Thomas; Rubin, Jeffrey S.; Fingert, John H.; Sheffield, Val C.; Stone, Edwin M.; Clark, Abbot F.

2008-01-01

Elevated intraocular pressure (IOP) is the principal risk factor for glaucoma and results from excessive impedance of the fluid outflow from the eye. This abnormality likely originates from outflow pathway tissues such as the trabecular meshwork (TM), but the associated molecular etiology is poorly understood. We discovered what we believe to be a novel role for secreted frizzled-related protein-1 (sFRP-1), an antagonist of Wnt signaling, in regulating IOP. sFRP1 was overexpressed in human glaucomatous TM cells. Genes involved in the Wnt signaling pathway were expressed in cultured TM cells and human TM tissues. Addition of recombinant sFRP-1 to ex vivo perfusion-cultured human eyes decreased outflow facility, concomitant with reduced levels of β-catenin, the Wnt signaling mediator, in the TM. Intravitreal injection of an adenoviral vector encoding sFRP1 in mice produced a titer-dependent increase in IOP. Five days after vector injection, IOP increased 2 fold, which was significantly reduced by topical ocular administration of an inhibitor of a downstream suppressor of Wnt signaling. Thus, these data indicate that increased expression of sFRP1 in the TM appears to be responsible for elevated IOP in glaucoma and restoring Wnt signaling in the TM may be a novel disease intervention strategy for treating glaucoma. PMID:18274669

Real-Time Aerodynamic Flow and Data Visualization in an Interactive Virtual Environment

NASA Technical Reports Server (NTRS)

Schwartz, Richard J.; Fleming, Gary A.

2005-01-01

Significant advances have been made to non-intrusive flow field diagnostics in the past decade. Camera based techniques are now capable of determining physical qualities such as surface deformation, surface pressure and temperature, flow velocities, and molecular species concentration. In each case, extracting the pertinent information from the large volume of acquired data requires powerful and efficient data visualization tools. The additional requirement for real time visualization is fueled by an increased emphasis on minimizing test time in expensive facilities. This paper will address a capability titled LiveView3D, which is the first step in the development phase of an in depth, real time data visualization and analysis tool for use in aerospace testing facilities.

The Influence of Scleral Flap Thickness, Shape, and Sutures on Intraocular Pressure (IOP) and Aqueous Humor Flow Direction in a Trabeculectomy Model.

PubMed

Samsudin, Amir; Eames, Ian; Brocchini, Steve; Khaw, Peng Tee

2016-07-01

Intraocular pressure and aqueous humor flow direction determined by the scleral flap immediately after trabeculectomy are critical determinants of the surgical outcome. We used a large-scale model to objectively measure the influence of flap thickness and shape, and suture number and position on pressure difference across the flap and flow of fluid underneath it. The model exploits the principle of dynamic and geometric similarity, so while dimensions were up to 30× greater than actual, the flow had similar properties. Scleral flaps were represented by transparent 0.8- and 1.6-mm-thick silicone sheets on an acrylic plate. Dyed 98% glycerin, representing the aqueous humor was pumped between the sheet and plate, and the equilibrium pressure measured with a pressure transducer. Image analysis based on the principle of dye dilution was performed using MATLAB software. The pressure drop across the flap was larger with thinner flaps, due to reduced rigidity and resistance. Doubling the surface area of flaps and reducing the number of sutures from 5 to 3 or 2 also resulted in larger pressure drops. Flow direction was affected mainly by suture number and position, it was less toward the sutures and more toward the nearest free edge of the flap. Posterior flow of aqueous humor was promoted by placing sutures along the sides while leaving the posterior edge free. We demonstrate a new physical model which shows how changes in scleral flap thickness and shape, and suture number and position affect pressure and flow in a trabeculectomy.

Real-Time Unsteady Loads Measurements Using Hot-Film Sensors

NASA Technical Reports Server (NTRS)

Mangalam, Arun S.; Moes, Timothy R.

2004-01-01

Several flight-critical aerodynamic problems such as buffet, flutter, stall, and wing rock are strongly affected or caused by abrupt changes in unsteady aerodynamic loads and moments. Advanced sensing and flow diagnostic techniques have made possible simultaneous identification and tracking, in real-time, of the critical surface, viscosity-related aerodynamic phenomena under both steady and unsteady flight conditions. The wind tunnel study reported here correlates surface hot-film measurements of leading edge stagnation point and separation point, with unsteady aerodynamic loads on a NACA 0015 airfoil. Lift predicted from the correlation model matches lift obtained from pressure sensors for an airfoil undergoing harmonic pitchup and pitchdown motions. An analytical model was developed that demonstrates expected stall trends for pitchup and pitchdown motions. This report demonstrates an ability to obtain unsteady aerodynamic loads in real-time, which could lead to advances in air vehicle safety, performance, ride-quality, control, and health management.

Qualitative analysis of tackifier resins in pressure sensitive adhesives using direct analysis in real time time-of-flight mass spectrometry.

PubMed

Mess, Aylin; Vietzke, Jens-Peter; Rapp, Claudius; Francke, Wittko

2011-10-01

Tackifier resins play an important role as additives in pressure sensitive adhesives (PSAs) to modulate their desired properties. With dependence on their origin and processing, tackifier resins can be multicomponent mixtures. Once they have been incorporated in a polymer matrix, conventional chemical analysis of tackifiers usually tends to be challenging because a suitable sample pretreatment and/or separation is necessary and all characteristic components have to be detected for an unequivocal identification of the resin additive. Nevertheless, a reliable analysis of tackifiers is essential for product quality and safety reasons. A promising approach for the examination of tackifier resins in PSAs is the novel direct analysis in real time mass spectrometry (DART-MS) technique, which enables screening analysis without time-consuming sample preparation. In the present work, four key classes of tackifier resins were studied (rosin, terpene phenolic, polyterpene, and hydrocarbon resins). Their corresponding complex mass spectra were interpreted and used as reference spectra for subsequent analyses. These data were used to analyze tackifier additives in synthetic rubber and acrylic adhesive matrixes. To prove the efficiency of the developed method, complete PSA products containing two or three different tackifiers were analyzed. The tackifier resins were successfully identified, while measurement time and interpretation took less than 10 mins per sample. Determination of resin additives in PSAs can be performed down to 0.1% (w/w, limit of detection) using the three most abundant signals for each tackifier. In summary, DART-MS is a rapid and efficient screening method for the analysis of various tackifiers in PSAs.

Scheduling Dependent Real-Time Activities

DTIC Science & Technology

1990-08-01

dependency relationships in a way that is suitable for all real - time systems . This thesis provides an algorithm, called DASA, that is effective for...scheduling the class of real - time systems known as supervisory control systems. Simulation experiments that account for the time required to make scheduling

Comparison of different intraocular pressure measurement techniques in normal eyes and post small incision lenticule extraction

PubMed Central

Hosny, Mohamed; Aboalazayem, Fayrouz; El Shiwy, Hoda; Salem, Mohsen

2017-01-01

Purpose The purpose of the study was to determine the accuracy of intraocular pressure (IOP) measurement after small incision lenticule extraction (SMILE) using Goldmann applanation tonometry (GAT) and ocular response analyzer (ORA). Methods This is a prospective clinical study that was conducted on 30 eyes in the interval between February 2016 and September 2016. The age of the patients ranged between 19 and 40 years. The patients underwent SMILE surgery using the femto laser. IOP was measured preoperatively and 1 month postoperatively by both techniques, the GAT and the ORA. Results GAT recorded lower values than ORA values (IOPcc) preoperatively and postoperatively and the difference was statistically significant. Both GAT and ORA IOP measurements decreased after SMILE. There was no statistically significant correlation between the changes in the GAT and ORA readings and the postoperative corneal pachymetry or the lenticule thickness. Both corneal hysteresis and corneal resistance factor showed significant decline after the procedure, which correlated with the lenticule thickness. Conclusion SMILE causes significant reduction in IOP measurement by ORA and GAT. Corneal biomechanics decreases following SMILE and this correlates with lenticule thickness. PMID:28761329

Longitudinal stability of the diurnal rhythm of intraocular pressure in subjects with healthy eyes, ocular hypertension and pigment dispersion syndrome.

PubMed

Huchzermeyer, Cord; Reulbach, Udo; Horn, Folkert; Lämmer, Robert; Mardin, Christian Y; Jünemann, Anselm G M

2014-10-15

The diurnal fluctuation of intraocular pressure may be relevant in glaucoma. The aim of this study was to find out whether the timing of diurnal fluctuation is stable over the years. Long-term IOP data from the Erlangen Glaucoma Registry, consisting of several annual extended diurnal IOP profiles for each patient, was retrospectively analyzed. Normal subjects, patients with ocular hypertension and with pigment dispersion syndrome were included because these subjects had not been treated with antiglaucomatous medications at the time of data acquisition. A cosine curve was fitted to the IOP data and the stability of individual rhythms over the years was tested using the Rayleigh test. To compare the peak times among groups, means were calculated only from subjects with a significant Rayleigh test. Of the fifty-two eligible subjects, a total of 364 extended diurnal IOP profiles measured in a sitting position had been collected over a period of 114 ± 39 months. The Rayleigh test indicated intraindividual stability of phase timing only in 19 subjects (36%). In subjects with pigment dispersions syndrome, peak IOP occurred on average two hours and seven minutes later during the day compared with subjects without this condition (p = 0.05). Fitting of cosine curves to the clinical IOP profiles was generally feasible, although careful interpretation is warranted due to lack of measurements in supine position and between midnight and 7 am. The interesting observation of a phase lag in eyes with pigment dispersion syndrome warrants confirmation and exploration in future prospective studies. The analysis of the IOP data showed no stable individual rhythm in the long term in a majority of patients.

Real-Time Nonlinear Optical Information Processing.

DTIC Science & Technology

1979-06-01

operations aree presented. One approach realizes the halftone method of nonlinear optical processing in real time by replacing the conventional...photographic recording medium with a real-time image transducer. In the second approach halftoning is eliminated and the real-time device is used directly

Intraocular Pressure Changes during Accommodation in Progressing Myopes, Stable Myopes and Emmetropes

PubMed Central

Jiang, Xiaodan; Hu, Xiaodan; Zhang, Mingzhou; Li, Xuemin

2015-01-01

Purpose To investigate the changes of intraocular pressure (IOP) induced by 3-diopter (3 D) accommodation in progressing myopes, stable myopes and emmetropes. Design Cross-sectional study. Participants 318 subjects including 270 myopes and 48 emmetropes. Methods 195 progressing myopes, 75 stable myopes and 48 emmetropes participated in this study. All subjects had their IOP measured using iCare rebound tonometer while accommodative stimuli of 0 D and 3 D were presented. Main Outcome Measures IOP values without accommodation and with 3 D accommodation were measured in all subjects. Baseline IOPs and IOP changes were compared within and between groups. Results There was no significant difference in IOPs between progressing myopes, stable myopes and emmetropes when no accommodation was induced (17.47±3.46, 16.62±2.98 and 16.80±3.62 respectively, p>0.05). IOP experienced an insignificantly slight decrease after 3 D accommodation in three groups (mean change -0.19±2.16, -0.03±1.68 and -0.39±2.65 respectively, p>0.05). Subgroup analysis showed in progressing myopic group, IOP of children (<18 years old) declined with accommodation while IOP of adults (≥18 years) increased, and the difference was statistically significant (p = 0.008). However, after excluding the age factor, accommodation induced IOP changes of high progressing myopes (≤-6 D), low, moderate and non-myopes (>-6 D) was not significantly different after Bonferroni correction (p = 0.838). Conclusions Although no difference was detected between the baseline IOPs and accommodation induced IOP changes in progressing myopes, stable myopes and emmetropes, this study found accommodation could cause transient IOP elevation in adult progressing myopes. PMID:26517725

Processes for manufacturing multifocal diffractive-refractive intraocular lenses

NASA Astrophysics Data System (ADS)

Iskakov, I. A.

2017-09-01

Manufacturing methods and design features of modern diffractive-refractive intraocular lenses are discussed. The implantation of multifocal intraocular lenses is the most optimal method of restoring the accommodative ability of the eye after removal of the natural lens. Diffractive-refractive intraocular lenses are the most widely used implantable multifocal lenses worldwide. Existing methods for manufacturing such lenses implement various design solutions to provide the best vision function after surgery. The wide variety of available diffractive-refractive intraocular lens designs reflects the demand for this method of vision correction in clinical practice and the importance of further applied research and development of new technologies for designing improved lens models.

Time flies faster under time pressure.

PubMed

Rattat, Anne-Claire; Matha, Pauline; Cegarra, Julien

2018-04-01

We examined the effects of time pressure on duration estimation in a verbal estimation task and a production task. In both temporal tasks, participants had to solve mazes in two conditions of time pressure (with or without), and with three different target durations (30 s, 60 s, and 90 s). In each trial of the verbal estimation task, participants had to estimate in conventional time units (minutes and seconds) the amount of time that had elapsed since they started to solve the maze. In the production task, they had to press a key while solving the maze when they thought that the trial's duration had reached a target value. Results showed that in both tasks, durations were judged longer with time pressure than without it. However, this temporal overestimation under time pressure did not increase with the length of the target duration. These results are discussed within the framework of scalar expectancy theory. Copyright © 2018 Elsevier B.V. All rights reserved.

The impact of intraocular pressure reduction on retrobulbar hemodynamic parameters in patients with open-angle glaucoma.

PubMed

Marjanovic, Ivan; Milic, Natasa; Martinez, Antonio

2012-01-01

To assess the retrobulbar hemodynamic parameters in the ophthalmic artery (OA), central retinal artery (CRA), and short posterior ciliary arteries (PCA) after decreasing elevated intraocular pressure (IOP) in patients with open-angle glaucoma (OAG) by using color Doppler imaging. A total of 46 eyes from 46 patients with OAG, with elevated IOP, were consecutively included in this prospective study. Peak-systolic velocity, end-diastolic velocity, and Pourcelot resistivity index were assessed in the OA, CRA, and PCA. The IOP was measured with Goldmann applanation tonometer (GAT) and the dynamic contour tonometer (DCT), 3 times respectively. Ocular pulse amplitude (OPA) appeared during the DCT measurement. After decreasing the elevated IOP, measured with both GAT and DCT, the retrobulbar parameters showed no differences as compared with baseline measurements. After Bonferroni correction (p ≤ 0.0042, alpha/12), statistical significance appeared in retrobulbar hemodynamics only in DCT (29.3 ± 6.4 vs 15.5 ± 4.2 mmHg), GAT (33.0 ± 8.3 vs 15.8 ± 7.0 mmHg), and OPA measurements (4.1 ± 1.3 vs 2.7 ± 1.4 mmHg), in comparison to baseline. There was no correlation between the changes in IOP measured with either DCT or GAT and the changes in the retrobulbar hemodynamic parameters (p>0.05 for all). The results of our study suggested a lack of correlation between the changes in IOP, measured with either DCT or GAT, and the changes in the retrobulbar hemodynamic parameters. The results of our study might suggest that the blood flow disturbances found in glaucoma patients are independent of the IOP.

Simplifying "target" intraocular pressure for different stages of primary open-angle glaucoma and primary angle-closure glaucoma.

PubMed

Sihota, Ramanjit; Angmo, Dewang; Ramaswamy, Deepa; Dada, Tanuj

2018-04-01

Lowering of intraocular pressure is currently the only therapeutic measure for Glaucoma management. Many longterm, randomized trials have shown the efficacy of lowering IOP, either by a percentage of baseline, or to a specified level. This has lead to the concept of 'Target" IOP, a range of IOP on therapy, that would stabilize the Glaucoma/prevent further visual field loss, without significantly affecting a patient's quality of life. A clinical staging of Glaucoma by optic nerve head evaluation and perimetric parameters, allows a patient's eye to be categorized as having - mild, moderate or severe Glaucomatous damage. An initial attempt should be made to achieve the following IOP range for both POAG or PACG after an iridotomy. In mild glaucoma the initial target IOP range could be kept as 15-17 mmHg, for moderate glaucoma 12-15 mmHg and in the severe stage of glaucomatous damage 10-12 mmHg. Factoring in baseline IOP, age, vascular perfusion parameters, and change on perimetry or imaging during follow up, this range may be reassessed over 6 months to a year. "Target" IOP requires further lowering when the patient continues to progress or develops a systemic disease such as a TIA. Conversely, in the event of a very elderly or sick patient with stable nerve and visual field over time, the target IOP could be raised and medications reduced. An appropriate use of medications/laser/surgery to achieve such a "Target" IOP range in POAG or PACG can maintain visual fields and quality of life, preventing Glaucoma blindness.

Effects of premedication with oral gabapentin on intraocular pressure changes following tracheal intubation in clinically normal dogs.

PubMed

Trbolova, Alexandra; Ghaffari, Masoud Selk; Capik, Igor

2017-09-19

Gabapentin is an antiepileptic drug widely approved as an add-on therapy for epilepsy treatment in human and dogs. There is a clinical impression that gabapentin is a suitable drug which attenuates the IOP elevation associated with tracheal intubation in humans. The present study performed to determine the effects of oral gabapentin on intraocular pressure (IOP) changes following tracheal intubation in dogs. Twenty adult healthy dogs were randomly assigned to treatment (n = 10) and control (n = 10) groups. Dogs in the treatment group received oral gabapentin (50 mg/kg) 2 h before induction of anesthesia and dogs in the control group received oral gelatin capsule placebo at the same time. The dogs were anesthetized with propofol 6 mg/kg, and anesthesia was maintained with a constant infusion of 0.2 mg/kg/min of propofol for 20 min. IOP were measured immediately before induction and then repeated immediately after induction, as well as 5 min, 10 min and 15 min following tracheal intubation in both groups. IOP was significantly higher immediately after induction, and 5 min after tracheal intubation when compared with IOP reading before induction in the control group. There was no statistically significant change in IOPs immediately after induction, and 5 min after tracheal intubation in comparison to the values before induction in the treatment group. Based on the findings of this study, preanesthetic oral administration of gabapentin significantly prevents an increase in the IOP associated with tracheal intubation in dogs anesthetized with propofol.

Real-Time and Near Real-Time Data for Space Weather Applications and Services

NASA Astrophysics Data System (ADS)

Singer, H. J.; Balch, C. C.; Biesecker, D. A.; Matsuo, T.; Onsager, T. G.

2015-12-01

Space weather can be defined as conditions in the vicinity of Earth and in the interplanetary environment that are caused primarily by solar processes and influenced by conditions on Earth and its atmosphere. Examples of space weather are the conditions that result from geomagnetic storms, solar particle events, and bursts of intense solar flare radiation. These conditions can have impacts on modern-day technologies such as GPS or electric power grids and on human activities such as astronauts living on the International Space Station or explorers traveling to the moon or Mars. While the ultimate space weather goal is accurate prediction of future space weather conditions, for many applications and services, we rely on real-time and near-real time observations and model results for the specification of current conditions. In this presentation, we will describe the space weather system and the need for real-time and near-real time data that drive the system, characterize conditions in the space environment, and are used by models for assimilation and validation. Currently available data will be assessed and a vision for future needs will be given. The challenges for establishing real-time data requirements, as well as acquiring, processing, and disseminating the data will be described, including national and international collaborations. In addition to describing how the data are used for official government products, we will also give examples of how these data are used by both the public and private sector for new applications that serve the public.

Software Design Methods for Real-Time Systems

DTIC Science & Technology

1989-12-01

This module describes the concepts and methods used in the software design of real time systems . It outlines the characteristics of real time systems , describes...the role of software design in real time system development, surveys and compares some software design methods for real - time systems , and

In-flight demonstration of a Real-Time Flush Airdata Sensing (RT-FADS) system

NASA Technical Reports Server (NTRS)

Whitmore, Stephen A.; Davis, Roy J.; Fife, John Michael

1995-01-01

A prototype real-time flush airdata sensing (RT-FADS) system has been developed and flight tested at the NASA Dryden Flight Research Center. This system uses a matrix of pressure orifices on the vehicle nose to estimate airdata parameters in real time using nonlinear regression. The algorithm is robust to sensor failures and noise in the measured pressures. The RT-FADS system has been calibrated using inertial trajectory measurements that were bootstrapped for atmospheric conditions using meteorological data. Mach numbers as high as 1.6 and angles of attack greater than 45 deg have been tested. The system performance has been evaluated by comparing the RT-FADS to the ship system airdata computer measurements to give a quantitative evaluation relative to an accepted measurement standard. Nominal agreements of approximately 0.003 in Mach number and 0.20 deg in angle of attack and angle of sideslip have been achieved.

Research of real-time communication software

NASA Astrophysics Data System (ADS)

Li, Maotang; Guo, Jingbo; Liu, Yuzhong; Li, Jiahong

2003-11-01

Real-time communication has been playing an increasingly important role in our work, life and ocean monitor. With the rapid progress of computer and communication technique as well as the miniaturization of communication system, it is needed to develop the adaptable and reliable real-time communication software in the ocean monitor system. This paper involves the real-time communication software research based on the point-to-point satellite intercommunication system. The object-oriented design method is adopted, which can transmit and receive video data and audio data as well as engineering data by satellite channel. In the real-time communication software, some software modules are developed, which can realize the point-to-point satellite intercommunication in the ocean monitor system. There are three advantages for the real-time communication software. One is that the real-time communication software increases the reliability of the point-to-point satellite intercommunication system working. Second is that some optional parameters are intercalated, which greatly increases the flexibility of the system working. Third is that some hardware is substituted by the real-time communication software, which not only decrease the expense of the system and promotes the miniaturization of communication system, but also aggrandizes the agility of the system.

Characterization of Intraocular Pressure Increases and Management Strategies Following Treatment With Fluocinolone Acetonide Intravitreal Implants in the FAME Trials.

PubMed

Parrish, Richard K; Campochiaro, Peter A; Pearson, P Andrew; Green, Ken; Traverso, Carlo E

2016-05-01

To compare elevated intraocular pressure (IOP) management and outcomes among patients with diabetic macular edema who received fluocinolone acetonide (FAc) implants versus sham-control treatment and explore the prior ocular steroid exposure impact on IOP outcomes. Best-corrected visual acuity (BCVA) was measured using Early Treatment Diabetic Retinopathy Study charts or electronic VA testers. Goldmann applanation tonometry was used to measure IOP. Elevated IOP was more common in FAc-versus sham control-treated patients. Medication, and less often trabeculoplasty or surgery, was used to lower IOP without affecting VA outcomes. No patient treated with 0.2 µg/day FAc who received prior ocular steroid required IOP-lowering surgery. Elevated IOP may occur following FAc implant receipt; however, in the present study, it was manageable and did not impact vision outcomes. Patients previously treated with ocular steroid did not require IOP-lowering surgery following 0.2 µg/day FAc implant administration. [Ophthalmic Surg Lasers Imaging Retina. 2016;47:426-435.]. Copyright 2016, SLACK Incorporated.

The role of cerebrospinal fluid pressure in glaucoma and other ophthalmic diseases: A review

PubMed Central

Fleischman, David; Allingham, R. Rand

2013-01-01

Glaucoma is one of the most common causes of blindness in the world. Well-known risk factors include age, race, a positive family history and elevated intraocular pressures. A newly proposed risk factor is decreased cerebrospinal fluid pressure (CSFP). This concept is based on the notion that a pressure differential exists across the lamina cribrosa, which separates the intraocular space from the subarachnoid fluid space. In this construct, an increased translaminar pressure difference will occur with a relative increase in elevated intraocular pressure or a reduction in CSFP. This net change in pressure is proposed to act on the tissues within the optic nerve head, potentially contributing to glaucomatous optic neuropathy. Similarly, patients with ocular hypertension who have elevated CSFPs, would enjoy a relatively protective effect from glaucomatous damage. This review will focus on the current literature pertaining to the role of CSFP in glaucoma. Additionally, the authors examine the relationship between glaucoma and other known CSFP-related ophthalmic disorders. PMID:24227969

INTRAOCULAR LENS SCAFFOLD TO PREVENT INTRAOCULAR FOREIGN BODY SLIPPAGE.

PubMed

Agarwal, Amar; Ashok Kumar, Dhivya; Agarwal, Athiya

2017-01-01

To report the application of intraocular lens (IOL) scaffold technique in intraocular foreign body (IOFB) removal. Patient with IOFB in posterior segment is included. The IOFB is retrieved from the posterior segment (pars plana vitrectomy and exteriorization of the IOFB from the retinal surface using an intravitreal forceps via the posterior capsulotomy) and placed on the iris. A three-piece posterior chamber IOL is placed in the sulcus via the clear corneal incision. IOFB is then removed from the anterior chamber over the IOL by forceps. Metallic IOFB of 4 mm × 3 mm has been retrieved by IOL scaffold technique after rescuing it from the posterior segment. There has been no drop or slip of IOFB in the vitreous during removal. Posterior chamber IOL served as scaffold during IOFB removal from anterior chamber. The IOL scaffold maneuver has shown to prevent slippage by acting as a barrier between the IOFB and the vitreous.

Hard real-time closed-loop electrophysiology with the Real-Time eXperiment Interface (RTXI)

PubMed Central

George, Ansel; Dorval, Alan D.; Christini, David J.

2017-01-01

The ability to experimentally perturb biological systems has traditionally been limited to static pre-programmed or operator-controlled protocols. In contrast, real-time control allows dynamic probing of biological systems with perturbations that are computed on-the-fly during experimentation. Real-time control applications for biological research are available; however, these systems are costly and often restrict the flexibility and customization of experimental protocols. The Real-Time eXperiment Interface (RTXI) is an open source software platform for achieving hard real-time data acquisition and closed-loop control in biological experiments while retaining the flexibility needed for experimental settings. RTXI has enabled users to implement complex custom closed-loop protocols in single cell, cell network, animal, and human electrophysiology studies. RTXI is also used as a free and open source, customizable electrophysiology platform in open-loop studies requiring online data acquisition, processing, and visualization. RTXI is easy to install, can be used with an extensive range of external experimentation and data acquisition hardware, and includes standard modules for implementing common electrophysiology protocols. PMID:28557998

[Correction of aphakia with the implantation of the retropupillary iris clip intraocular artificial lens].

PubMed

Szabó, Antal; Papp, András; Borbándy, Ágnes; D Géhl, Zsuzsanna; Nagy, Zoltán Zsolt; Resch, Miklós

2017-01-01

The correction of aphakia might be a challenge for the surgeon. The aim of this study is to describe the authors' experience with the implantation of the retropupillary iris clip intraocular lens. Patients between January 2014 and December 2015 were included in the retrospective study. Retropupillary implantation of iris clip intraocular lens VRSA 54 (AMO Advanced Medical Optics, USA) was performed in all cases. The minimum follow up period was three months. The stability of the intraocular lens and the intraoperative and postoperative complications and the visual acuity were evaluated. During this time period 11 cases (1 female, 10 males) were included in the study. The mean age at the time of the implantation was 57.7 years (between 25-74 years). In 4 cases the iris clip lens was implanted during the first intervention, in 7 cases during the secondary procedure. In all cases the lens was fixated onto the iris posteriorly. The best corrected visual acuity before the iris clip implantation was 0.43 (0.1-1.0) and postoperatively at the time of the follow up 0.49 (0.04-1.0). With the use of the retropupillary implanted iris clip intraocular lens all of the patients could have been rehabilitated without major complications. Orv. Hetil., 2017, 158(1), 20-24.

ControlShell - A real-time software framework

NASA Technical Reports Server (NTRS)

Schneider, Stanley A.; Ullman, Marc A.; Chen, Vincent W.

1991-01-01

ControlShell is designed to enable modular design and impplementation of real-time software. It is an object-oriented tool-set for real-time software system programming. It provides a series of execution and data interchange mechansims that form a framework for building real-time applications. These mechanisms allow a component-based approach to real-time software generation and mangement. By defining a set of interface specifications for intermodule interaction, ControlShell provides a common platform that is the basis for real-time code development and exchange.

[Exoskeleton robot system based on real-time gait analysis for walking assist].

PubMed

Xie, Zheng; Wang, Mingjiang; Huang, Wulong; Yong, Shanshan; Wang, Xin'an

2017-04-01

This paper presents a wearable exoskeleton robot system to realize walking assist function, which oriented toward the patients or the elderly with the mild impairment of leg movement function, due to illness or natural aging. It reduces the loads of hip, knee, ankle and leg muscles during walking by way of weight support. In consideration of the characteristics of the psychological demands and the disease, unlike the weight loss system in the fixed or followed rehabilitation robot, the structure of the proposed exoskeleton robot is artistic, lightweight and portable. The exoskeleton system analyzes the user's gait real-timely by the plantar pressure sensors to divide gait phases, and present different control strategies for each gait phase. The pressure sensors in the seat of the exoskeleton system provide real-time monitoring of the support efforts. And the drive control uses proportion-integral-derivative (PID) control technology for torque control. The total weight of the robot system is about 12.5 kg. The average of the auxiliary support is about 10 kg during standing, and it is about 3 kg during walking. The system showed, in the experiments, a certain effect of weight support, and reduction of the pressure on the lower limbs to walk and stand.

Real-Time, Non-Intrusive Detection of Liquid Nitrogen in Liquid Oxygen at High Pressure and High Flow

NASA Technical Reports Server (NTRS)

Singh, Jagdish P.; Yueh, Fang-Yu; Kalluru, Rajamohan R.; Harrison, Louie

2012-01-01

An integrated fiber-optic Raman sensor has been designed for real-time, nonintrusive detection of liquid nitrogen in liquid oxygen (LOX) at high pressures and high flow rates in order to monitor the quality of LOX used during rocket engine ground testing. The integrated sensor employs a high-power (3-W) Melles Griot diode-pumped, solid-state (DPSS), frequency-doubled Nd:YAG 532- nm laser; a modified Raman probe that has built-in Raman signal filter optics; two high-resolution spectrometers; and photomultiplier tubes (PMTs) with selected bandpass filters to collect both N2 and O2 Raman signals. The PMT detection units are interfaced with National Instruments Lab- VIEW for fast data acquisition. Studies of sensor performance with different detection systems (i.e., spectrometer and PMT) were carried out. The concentration ratio of N2 and O2 can be inferred by comparing the intensities of the N2 and O2 Raman signals. The final system was fabricated to measure N2 and O2 gas mixtures as well as mixtures of liquid N2 and LOX

Piggyback intraocular lens implantation to correct pseudophakic refractive error after segmental multifocal intraocular lens implantation.

PubMed

Venter, Jan A; Oberholster, Andre; Schallhorn, Steven C; Pelouskova, Martina

2014-04-01

To evaluate refractive and visual outcomes of secondary piggyback intraocular lens implantation in patients diagnosed as having residual ametropia following segmental multifocal lens implantation. Data of 80 pseudophakic eyes with ametropia that underwent Sulcoflex aspheric 653L intraocular lens implantation (Rayner Intraocular Lenses Ltd., East Sussex, United Kingdom) to correct residual refractive error were analyzed. All eyes previously had in-the-bag zonal refractive multifocal intraocular lens implantation (Lentis Mplus MF30, models LS-312 and LS-313; Oculentis GmbH, Berlin, Germany) and required residual refractive error correction. Outcome measurements included uncorrected distance visual acuity, corrected distance visual acuity, uncorrected near visual acuity, distance-corrected near visual acuity, manifest refraction, and complications. One-year data are presented in this study. The mean spherical equivalent ranged from -1.75 to +3.25 diopters (D) preoperatively (mean: +0.58 ± 1.15 D) and reduced to -1.25 to +0.50 D (mean: -0.14 ± 0.28 D; P < .01). Postoperatively, 93.8% of eyes were within ±0.50 D and 98.8% were within ±1.00 D of emmetropia. The mean uncorrected distance visual acuity improved significantly from 0.28 ± 0.16 to 0.01 ± 0.10 logMAR and 78.8% of eyes achieved 6/6 (Snellen 20/20) or better postoperatively. The mean uncorrected near visual acuity changed from 0.43 ± 0.28 to 0.19 ± 0.15 logMAR. There was no significant change in corrected distance visual acuity or distance-corrected near visual acuity. No serious intraoperative or postoperative complications requiring secondary intraocular lens removal occurred. Sulcoflex lenses proved to be a predictable and safe option for correcting residual refractive error in patients diagnosed as having pseudophakia. Copyright 2014, SLACK Incorporated.

Allometry and Scaling of the Intraocular Pressure and Aqueous Humour Flow Rate in Vertebrate Eyes.

PubMed

Zouache, Moussa A; Eames, Ian; Samsudin, Amir

2016-01-01

In vertebrates, intraocular pressure (IOP) is required to maintain the eye into a shape allowing it to function as an optical instrument. It is sustained by the balance between the production of aqueous humour by the ciliary body and the resistance to its outflow from the eye. Dysregulation of the IOP is often pathological to vision. High IOP may lead to glaucoma, which is in man the second most prevalent cause of blindness. Here, we examine the importance of the IOP and rate of formation of aqueous humour in the development of vertebrate eyes by performing allometric and scaling analyses of the forces acting on the eye during head movement and the energy demands of the cornea, and testing the predictions of the models against a list of measurements in vertebrates collated through a systematic review. We show that the IOP has a weak dependence on body mass, and that in order to maintain the focal length of the eye, it needs to be an order of magnitude greater than the pressure drop across the eye resulting from gravity or head movement. This constitutes an evolutionary constraint that is common to all vertebrates. In animals with cornea-based optics, this constraint also represents a condition to maintain visual acuity. Estimated IOPs were found to increase with the evolution of terrestrial animals. The rate of formation of aqueous humour was found to be adjusted to the metabolic requirements of the cornea, scaling as Vac(0.67), where Vac is the volume of the anterior chamber. The present work highlights an interdependence between IOP and aqueous flow rate crucial to ocular function that must be considered to understand the evolution of the dioptric apparatus. It should also be taken into consideration in the prevention and treatment of glaucoma.

Allometry and Scaling of the Intraocular Pressure and Aqueous Humour Flow Rate in Vertebrate Eyes

PubMed Central

Zouache, Moussa A.; Eames, Ian; Samsudin, Amir

2016-01-01

In vertebrates, intraocular pressure (IOP) is required to maintain the eye into a shape allowing it to function as an optical instrument. It is sustained by the balance between the production of aqueous humour by the ciliary body and the resistance to its outflow from the eye. Dysregulation of the IOP is often pathological to vision. High IOP may lead to glaucoma, which is in man the second most prevalent cause of blindness. Here, we examine the importance of the IOP and rate of formation of aqueous humour in the development of vertebrate eyes by performing allometric and scaling analyses of the forces acting on the eye during head movement and the energy demands of the cornea, and testing the predictions of the models against a list of measurements in vertebrates collated through a systematic review. We show that the IOP has a weak dependence on body mass, and that in order to maintain the focal length of the eye, it needs to be an order of magnitude greater than the pressure drop across the eye resulting from gravity or head movement. This constitutes an evolutionary constraint that is common to all vertebrates. In animals with cornea-based optics, this constraint also represents a condition to maintain visual acuity. Estimated IOPs were found to increase with the evolution of terrestrial animals. The rate of formation of aqueous humour was found to be adjusted to the metabolic requirements of the cornea, scaling as Vac0.67, where Vac is the volume of the anterior chamber. The present work highlights an interdependence between IOP and aqueous flow rate crucial to ocular function that must be considered to understand the evolution of the dioptric apparatus. It should also be taken into consideration in the prevention and treatment of glaucoma. PMID:26990431

Implantation of a Multifocal Toric Intraocular Lens after Radial Keratotomy and Cross-Linking with Hyperopia and Astigmatism Residues: A Case Report.

PubMed

Nuzzi, Raffaele; Monteu, Francesca; Tridico, Federico

2017-01-01

Radial keratotomy is a refractive surgical technique, widely used in the 80s and early 90s to correct myopia and astigmatism, but now overcome by more recent laser techniques. Important consequences, often in patients with more than 45 years of age, are progressive hyperopic shift and/or an increase in corneal astigmatism, whose main cause seems to be an increase in the curvature radius of the central portion of the cornea. This seems to be due to radial keratotomy incisions - with the consequent need for cross-linking - intraocular pressure, and corneal biomechanical parameters. The authors propose phacoemulsification with a customized multifocal toric intraocular lens implantation to correct the induced shift and hyperopic astigmatism. A decent postoperative visual acuity was observed with good patient satisfaction. A specific protocol must be applied to optimize the correct diagnosis, presurgical evaluation and postsurgical outcomes that are to be maintained over time, without regressions.

Method for Hot Real-Time Sampling of Gasification Products

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pomeroy, Marc D

The Thermochemical Process Development Unit (TCPDU) at the National Renewable Energy Laboratory (NREL) is a highly instrumented half-ton/day pilot scale plant capable of demonstrating industrially relevant thermochemical technologies from lignocellulosic biomass conversion, including gasification. Gasification creates primarily Syngas (a mixture of Hydrogen and Carbon Monoxide) that can be utilized with synthesis catalysts to form transportation fuels and other valuable chemicals. Biomass derived gasification products are a very complex mixture of chemical components that typically contain Sulfur and Nitrogen species that can act as catalysis poisons for tar reforming and synthesis catalysts. Real-time hot online sampling techniques, such as Molecular Beammore » Mass Spectrometry (MBMS), and Gas Chromatographs with Sulfur and Nitrogen specific detectors can provide real-time analysis providing operational indicators for performance. Sampling typically requires coated sampling lines to minimize trace sulfur interactions with steel surfaces. Other materials used inline have also shown conversion of sulfur species into new components and must be minimized. Sample line Residence time within the sampling lines must also be kept to a minimum to reduce further reaction chemistries. Solids from ash and char contribute to plugging and must be filtered at temperature. Experience at NREL has shown several key factors to consider when designing and installing an analytical sampling system for biomass gasification products. They include minimizing sampling distance, effective filtering as close to source as possible, proper line sizing, proper line materials or coatings, even heating of all components, minimizing pressure drops, and additional filtering or traps after pressure drops.« less

OPAD-EDIFIS Real-Time Processing

NASA Technical Reports Server (NTRS)

Katsinis, Constantine

1997-01-01

The Optical Plume Anomaly Detection (OPAD) detects engine hardware degradation of flight vehicles through identification and quantification of elemental species found in the plume by analyzing the plume emission spectra in a real-time mode. Real-time performance of OPAD relies on extensive software which must report metal amounts in the plume faster than once every 0.5 sec. OPAD software previously written by NASA scientists performed most necessary functions at speeds which were far below what is needed for real-time operation. The research presented in this report improved the execution speed of the software by optimizing the code without changing the algorithms and converting it into a parallelized form which is executed in a shared-memory multiprocessor system. The resulting code was subjected to extensive timing analysis. The report also provides suggestions for further performance improvement by (1) identifying areas of algorithm optimization, (2) recommending commercially available multiprocessor architectures and operating systems to support real-time execution and (3) presenting an initial study of fault-tolerance requirements.

Bilateral intraocular calcification in necrotizing cytomegalovirus retinitis.

PubMed

Tuncer, Samuray; Oray, Merih; Yildirim, Yeliz; Camcioglu, Yildiz; Tugal-Tutkun, Ilknur

2014-10-01

We report a unique case of bilateral intraocular calcification due to necrotizing cytomegalovirus (CMV) retinitis associated with congenital CMV infection. A 7-month-old boy with a history of congenital CMV infection showed bilateral intraocular calcific plaques on computed tomography (CT) and ultrasonography. We reviewed the patient's medical files for the purpose of this report. The patient had a prior medical history of hospitalization for fever and swelling in the neck at 3 months of age. Systemic findings (anemia, neutropenia, hepatosplenomegaly, and reactive lymphadenomegaly) in association with a low CD4 count, high blood CMV viral load, and positivity for urine CMV DNA by polymerase chain reaction led to the diagnosis of bone marrow suppression and congenital CMV infection. At 7 months, he developed horizontal nystagmus and bilateral leukocoria over 20 days. Cranial CT and ultrasonography revealed bilateral intraocular calcific plaques and the patient was referred to rule out retinoblastoma. Fundoscopy was consistent with bilateral hemorrhagic, necrotizing CMV retinitis. Significant resolution of the retinal infiltrations occurred 2 weeks after initiation of systemic treatment with ganciclovir. Intraocular calcification may be a sign of active CMV retinitis. To our knowledge this is the first report of bilateral intraocular calcification serving as the presenting clinical manifestation of necrotizing CMV retinitis.

[Real-time feedback systems for improvement of resuscitation quality].

PubMed

Lukas, R P; Van Aken, H; Engel, P; Bohn, A

2011-07-01

The quality of chest compression is a determinant of survival after cardiac arrest. Therefore, the European Resuscitation Council (ERC) 2010 guidelines on resuscitation strongly focus on compression quality. Despite its impact on survival, observational studies have shown that chest compression quality is not reached by professional rescue teams. Real-time feedback devices for resuscitation are able to measure chest compression during an ongoing resuscitation attempt through a sternal sensor equipped with a motion and pressure detection system. In addition to the electrocardiograph (ECG) ventilation can be detected by transthoracic impedance monitoring. In cases of quality deviation, such as shallow chest compression depth or hyperventilation, feedback systems produce visual or acoustic alarms. Rescuers can thereby be supported and guided to the requested quality in chest compression and ventilation. Feedback technology is currently available both as a so-called stand-alone device and as an integrated feature in a monitor/defibrillator unit. Multiple studies have demonstrated sustainable enhancement in the education of resuscitation due to the use of real-time feedback technology. There is evidence that real-time feedback for resuscitation combined with training and debriefing strategies can improve both resuscitation quality and patient survival. Chest compression quality is an independent predictor for survival in resuscitation and should therefore be measured and documented in further clinical multicenter trials.

EVALUATION OF REAL-TIME INNOVATIVE BIOLOGICAL AND CHEMICAL MONITORING SYSTEMS TO PROTECT SOURCE WATERS

EPA Science Inventory

Evaluation of Real-Time Innovative Biological and Chemical Monitoring Systems
To Protect Source Waters

Drinking water supplies have in recent years come under increasing pressure from regulatory concerns regarding TMDL designations and restoration strategies as well ...

[Changes of structures of anterior chamber angle in rabbit chronic high intraocular pressure model].

PubMed

Lei, Xun-wen; Wei, Ping; Li, Xiao-lin; Yang, Kan; Lei, Jian-zhen

2009-10-01

To observe the anterior chamber angle changes occurred in compound Carbomer-induced chronic high intraocular pressure (IOP) model in rabbit eyes. It was an experimental study. Thirty two rabbits were randomly divided into eight groups. Compound Carbomer (0.3%, 0.3 ml) was injected into the left anterior chamber. A group of rabbits were randomly killed after 1, 2, 3, 4, 6, 8, 10 and 12 weeks. The anterior chamber of the rabbit eye specimens was observed. IOP increased slowly following the application of the drug, high IOP lasted for 3 months. The drug-induced changes of anterior chamber angle consisted of early inflammatory response and late fibrous changes. Inflammatory response occurred in early stage and reduced or disappeared after 3 weeks. Fibrous degeneration and adhesion obstruction occurred in the anterior chamber angle after 4 weeks. Under the electron microscope, the trabecular was expanded and deformed, with hyperplasia of collagen and elastic fibers. Endothelial cells were separated from the trabecular, and showed the morphology of lymphocytes, with the function similar to the macrophages. Phagocytized Carbomer particles were transported through the vacuoles of Schlemm's canal endothelial cells. Large vacuoles gradually reduced. Excessive Carbomer particles were accumulated in the endothelial cells and obstructed the Schlemm's canal. This induced the fibrous proliferation and the destruction of anterior chamber angle structures. The obstruction of aqueous humor outflow induced by compound Carbomer in rabbit high IOP model is caused mainly by the changes in trabecular endothelial cells.

A real-time cabled observatory on the Cascadia subduction zone

NASA Astrophysics Data System (ADS)

Vidale, J. E.; Delaney, J. R.; Toomey, D. R.; Bodin, P.; Roland, E. C.; Wilcock, W. S. D.; Houston, H.; Schmidt, D. A.; Allen, R. M.

2015-12-01

Subduction zones are replete with mystery and rife with hazard. Along most of the Pacific Northwest margin, the traditional methods of monitoring offshore geophysical activity use onshore sensors or involve conducting infrequent oceanographic expeditions. This results in a limited capacity for detecting and monitoring subduction processes offshore. We propose that the next step in geophysical observations of Cascadia should include real-time data delivered by a seafloor cable with seismic, geodetic, and pressure-sensing instruments. Along the Cascadia subduction zone, we need to monitor deformation, earthquakes, and fluid fluxes on short time scales. High-quality long-term time series are needed to establish baseline observations and evaluate secular changes in the subduction environment. Currently we lack a basic knowledge of the plate convergence rate, direction and its variations along strike and of how convergence is accommodated across the plate boundary. We also would like to seek cycles of microseismicity, how far locking extends up-dip, and the transient processes (i.e., fluid pulsing, tremor, and slow slip) that occur near the trench. For reducing risk to society, real-time monitoring has great benefit for immediate and accurate assessment through earthquake early warning systems. Specifically, the improvement to early warning would be in assessing the location, geometry, and progression of ongoing faulting and obtaining an accurate tsunami warning, as well as simply speeding up the early warning. It would also be valuable to detect strain transients and map the locked portion of the megathrust, and detect changes in locking over the earthquake cycle. Development of the US portion of a real-time cabled seismic and geodetic observatory should build upon the Ocean Observatories Initiative's cabled array, which was recently completed and is currently delivering continuous seismic and pressure data from the seafloor. Its implementation would require

Real-time combustion control and diagnostics sensor-pressure oscillation monitor

DOEpatents

Chorpening, Benjamin T [Morgantown, WV; Thornton, Jimmy [Morgantown, WV; Huckaby, E David [Morgantown, WV; Richards, George A [Morgantown, WV

2009-07-14

An apparatus and method for monitoring and controlling the combustion process in a combustion system to determine the amplitude and/or frequencies of dynamic pressure oscillations during combustion. An electrode in communication with the combustion system senses hydrocarbon ions and/or electrons produced by the combustion process and calibration apparatus calibrates the relationship between the standard deviation of the current in the electrode and the amplitudes of the dynamic pressure oscillations by applying a substantially constant voltage between the electrode and ground resulting in a current in the electrode and by varying one or more of (1) the flow rate of the fuel, (2) the flow rate of the oxidant, (3) the equivalence ratio, (4) the acoustic tuning of the combustion system, and (5) the fuel distribution in the combustion chamber such that the amplitudes of the dynamic pressure oscillations in the combustion chamber are calculated as a function of the standard deviation of the electrode current. Thereafter, the supply of fuel and/or oxidant is varied to modify the dynamic pressure oscillations.

Research in Distributed Real-Time Systems

NASA Technical Reports Server (NTRS)

Mukkamala, R.

1997-01-01

This document summarizes the progress we have made on our study of issues concerning the schedulability of real-time systems. Our study has produced several results in the scalability issues of distributed real-time systems. In particular, we have used our techniques to resolve schedulability issues in distributed systems with end-to-end requirements. During the next year (1997-98), we propose to extend the current work to address the modeling and workload characterization issues in distributed real-time systems. In particular, we propose to investigate the effect of different workload models and component models on the design and the subsequent performance of distributed real-time systems.

Real-time Space-time Integration in GIScience and Geography

PubMed Central

Richardson, Douglas B.

2013-01-01

Space-time integration has long been the topic of study and speculation in geography. However, in recent years an entirely new form of space-time integration has become possible in GIS and GIScience: real-time space-time integration and interaction. While real-time spatiotemporal data is now being generated almost ubiquitously, and its applications in research and commerce are widespread and rapidly accelerating, the ability to continuously create and interact with fused space-time data in geography and GIScience is a recent phenomenon, made possible by the invention and development of real-time interactive (RTI) GPS/GIS technology and functionality in the late 1980s and early 1990s. This innovation has since functioned as a core change agent in geography, cartography, GIScience and many related fields, profoundly realigning traditional relationships and structures, expanding research horizons, and transforming the ways geographic data is now collected, mapped, modeled, and used, both in geography and in science and society more broadly. Real-time space-time interactive functionality remains today the underlying process generating the current explosion of fused spatiotemporal data, new geographic research initiatives, and myriad geospatial applications in governments, businesses, and society. This essay addresses briefly the development of these real-time space-time functions and capabilities; their impact on geography, cartography, and GIScience; and some implications for how discovery and change can occur in geography and GIScience, and how we might foster continued innovation in these fields. PMID:24587490

Real-time Space-time Integration in GIScience and Geography.

PubMed

Richardson, Douglas B

2013-01-01

Space-time integration has long been the topic of study and speculation in geography. However, in recent years an entirely new form of space-time integration has become possible in GIS and GIScience: real-time space-time integration and interaction. While real-time spatiotemporal data is now being generated almost ubiquitously, and its applications in research and commerce are widespread and rapidly accelerating, the ability to continuously create and interact with fused space-time data in geography and GIScience is a recent phenomenon, made possible by the invention and development of real-time interactive (RTI) GPS/GIS technology and functionality in the late 1980s and early 1990s. This innovation has since functioned as a core change agent in geography, cartography, GIScience and many related fields, profoundly realigning traditional relationships and structures, expanding research horizons, and transforming the ways geographic data is now collected, mapped, modeled, and used, both in geography and in science and society more broadly. Real-time space-time interactive functionality remains today the underlying process generating the current explosion of fused spatiotemporal data, new geographic research initiatives, and myriad geospatial applications in governments, businesses, and society. This essay addresses briefly the development of these real-time space-time functions and capabilities; their impact on geography, cartography, and GIScience; and some implications for how discovery and change can occur in geography and GIScience, and how we might foster continued innovation in these fields.

A Real-Time Systems Symposium Preprint.

DTIC Science & Technology

1983-09-01

Real - Time Systems Symposium Preprint Interim Tech...estimate of the occurence of the error. Unclassii ledSECUqITY CLASSIF’ICA T" NO MI*IA If’ inDI /’rrd erter for~~ble. ’Corrputnqg A REAL - TIME SYSTEMS SYMPOSIUM...ABSTRACT This technical report contains a preprint of a paper accepted for presentation at the REAL - TIME SYSTEMS SYMPOSIUM, Arlington,

Analysis of real-time vibration data

USGS Publications Warehouse

Safak, E.

2005-01-01

In recent years, a few structures have been instrumented to provide continuous vibration data in real time, recording not only large-amplitude motions generated by extreme loads, but also small-amplitude motions generated by ambient loads. The main objective in continuous recording is to track any changes in structural characteristics, and to detect damage after an extreme event, such as an earthquake or explosion. The Fourier-based spectral analysis methods have been the primary tool to analyze vibration data from structures. In general, such methods do not work well for real-time data, because real-time data are mainly composed of ambient vibrations with very low amplitudes and signal-to-noise ratios. The long duration, linearity, and the stationarity of ambient data, however, allow us to utilize statistical signal processing tools, which can compensate for the adverse effects of low amplitudes and high noise. The analysis of real-time data requires tools and techniques that can be applied in real-time; i.e., data are processed and analyzed while being acquired. This paper presents some of the basic tools and techniques for processing and analyzing real-time vibration data. The topics discussed include utilization of running time windows, tracking mean and mean-square values, filtering, system identification, and damage detection.

Flexible real-time magnetic resonance imaging framework.

PubMed

Santos, Juan M; Wright, Graham A; Pauly, John M

2004-01-01

The extension of MR imaging to new applications has demonstrated the limitations of the architecture of current real-time systems. Traditional real-time implementations provide continuous acquisition of data and modification of basic sequence parameters on the fly. We have extended the concept of real-time MRI by designing a system that drives the examinations from a real-time localizer and then gets reconfigured for different imaging modes. Upon operator request or automatic feedback the system can immediately generate a new pulse sequence or change fundamental aspects of the acquisition such as gradient waveforms excitation pulses and scan planes. This framework has been implemented by connecting a data processing and control workstation to a conventional clinical scanner. Key components on the design of this framework are the data communication and control mechanisms, reconstruction algorithms optimized for real-time and adaptability, flexible user interface and extensible user interaction. In this paper we describe the various components that comprise this system. Some of the applications implemented in this framework include real-time catheter tracking embedded in high frame rate real-time imaging and immediate switching between real-time localizer and high-resolution volume imaging for coronary angiography applications.

Smartphone-based Continuous Blood Pressure Measurement Using Pulse Transit Time.

PubMed

Gholamhosseini, Hamid; Meintjes, Andries; Baig, Mirza; Linden, Maria

2016-01-01

The increasing availability of low cost and easy to use personalized medical monitoring devices has opened the door for new and innovative methods of health monitoring to emerge. Cuff-less and continuous methods of measuring blood pressure are particularly attractive as blood pressure is one of the most important measurements of long term cardiovascular health. Current methods of noninvasive blood pressure measurement are based on inflation and deflation of a cuff with some effects on arteries where blood pressure is being measured. This inflation can also cause patient discomfort and alter the measurement results. In this work, a mobile application was developed to collate the PhotoPlethysmoGramm (PPG) waveform provided by a pulse oximeter and the electrocardiogram (ECG) for calculating the pulse transit time. This information is then indirectly related to the user's systolic blood pressure. The developed application successfully connects to the PPG and ECG monitoring devices using Bluetooth wireless connection and stores the data onto an online server. The pulse transit time is estimated in real time and the user's systolic blood pressure can be estimated after the system has been calibrated. The synchronization between the two devices was found to pose a challenge to this method of continuous blood pressure monitoring. However, the implemented continuous blood pressure monitoring system effectively serves as a proof of concept. This combined with the massive benefits that an accurate and robust continuous blood pressure monitoring system would provide indicates that it is certainly worthwhile to further develop this system.

Real-time photo-magnetic imaging.

PubMed

Nouizi, Farouk; Erkol, Hakan; Luk, Alex; Unlu, Mehmet B; Gulsen, Gultekin

2016-10-01

We previously introduced a new high resolution diffuse optical imaging modality termed, photo-magnetic imaging (PMI). PMI irradiates the object under investigation with near-infrared light and monitors the variations of temperature using magnetic resonance thermometry (MRT). In this paper, we present a real-time PMI image reconstruction algorithm that uses analytic methods to solve the forward problem and assemble the Jacobian matrix much faster. The new algorithm is validated using real MRT measured temperature maps. In fact, it accelerates the reconstruction process by more than 250 times compared to a single iteration of the FEM-based algorithm, which opens the possibility for the real-time PMI.

Making real-time reactive systems reliable

NASA Technical Reports Server (NTRS)

Marzullo, Keith; Wood, Mark

1990-01-01

A reactive system is characterized by a control program that interacts with an environment (or controlled program). The control program monitors the environment and reacts to significant events by sending commands to the environment. This structure is quite general. Not only are most embedded real time systems reactive systems, but so are monitoring and debugging systems and distributed application management systems. Since reactive systems are usually long running and may control physical equipment, fault tolerance is vital. The research tries to understand the principal issues of fault tolerance in real time reactive systems and to build tools that allow a programmer to design reliable, real time reactive systems. In order to make real time reactive systems reliable, several issues must be addressed: (1) How can a control program be built to tolerate failures of sensors and actuators. To achieve this, a methodology was developed for transforming a control program that references physical value into one that tolerates sensors that can fail and can return inaccurate values; (2) How can the real time reactive system be built to tolerate failures of the control program. Towards this goal, whether the techniques presented can be extended to real time reactive systems is investigated; and (3) How can the environment be specified in a way that is useful for writing a control program. Towards this goal, whether a system with real time constraints can be expressed as an equivalent system without such constraints is also investigated.

Retropupillary iris-claw intraocular lens for the surgical correction of aphakia in cases with microspherophakia.

PubMed

Fouda, Sameh Mosaad; Al Aswad, Mahmoud A; Ibrahim, Basem M; Bori, Ashraf; Mattout, Hala K

2016-12-01

This study aimed to evaluate the safety and efficacy of retropupillary fixation of an iris-claw intraocular lens (IOL; Verisyse polymethyl methacrylate IOL, Abbott Medical Optics [AMO], Netherlands) for the surgical correction of aphakia in microspherophakic eyes without sufficient capsular support. This was a prospective, interventional, noncomparative case series. This interventional case series comprised 17 eyes of 9 microspherophakic patients. Retropupillary fixation of the Verisyse iris-claw IOL (AMO) was performed in all cases. The surgical time was measured. Corrected distance visual acuity, astigmatism, intraocular pressure (IOP), tissue reaction, pigment dispersion, and stability of the IOL were studied 1 day, 3 days, 1 week, 2 weeks, 1 month, and 6 months postoperatively. Eight patients had familial microspherophakia and one patient had Marfan's syndrome. Eighty-two percent of the cases achieved a visual acuity of 0.3 or better. There was no significant postoperative inflammatory reaction. Transient elevation of IOP was recorded in two cases in the 1st week only. One IOL developed disengagement of one of the haptics from the iris and was successfully re-engaged. All the other IOLs were well centered and stable. The mean surgical time was 18.0 ± 4.5 min. Retropupillary fixation of an iris-claw IOL is a safe and effective procedure that provides early visual recovery. It is also a time-saving method for correcting aphakia in microspherophakic eyes without sufficient capsular support.

Reduced intraocular pressure after cataract surgery in patients with narrow angles and chronic angle-closure glaucoma.

PubMed

Brown, Reay H; Zhong, Le; Whitman, Allison L; Lynch, Mary G; Kilgo, Patrick D; Hovis, Kristen L

2014-10-01

To evaluate the effect of cataract surgery on intraocular pressure (IOP) in patients with narrow angles and chronic angle-closure glaucoma (ACG) and to determine whether the change in IOP was correlated with the preoperative pressure, axial length (AL), and anterior chamber depth (ACD). Private practice, Atlanta, Georgia, USA. Retrospective case series. Charts of patients with narrow angles or chronic ACG who had cataract surgery were reviewed. All eyes had previous laser iridotomies. Data recorded included preoperative and postoperative IOP, AL, and ACD. The preoperative IOP was used to stratify eyes into 4 groups. The charts of 56 patients (83 eyes) were reviewed. The mean reduction IOP in all eyes was 3.28 mm Hg (18%), with 88% having a decrease in IOP. There was a significant correlation between preoperative IOP and the magnitude of IOP reduction (r = 0.68, P < .001). The mean decrease in IOP was 5.3 mm Hg in eyes with a preoperative IOP above 20 mm Hg, 4.6 mm Hg in the over 18 to 20 mm Hg group, 2.5 mm Hg in the over 15 to 18 mm Hg group, and 1.4 mm Hg in the 15 mm Hg or less group. The mean follow-up was 3.0 years ± 2.3 (SD). Cataract surgery reduced IOP in patients with narrow angles and chronic ACG. The magnitude of reduction was highly correlated with preoperative IOP and weakly correlated with ACD. No author has a financial or proprietary interest in any material or method mentioned. Copyright © 2014 ASCRS and ESCRS. Published by Elsevier Inc. All rights reserved.

Visualization of Real-Time Data

NASA Technical Reports Server (NTRS)

Stansifer, Ryan; Engrand, Peter

1996-01-01

In this project we explored various approaches to presenting real-time data from the numerous systems monitored on the space shuttle to computer users. We examined the approach that several projects at the Kennedy Space Center (KSC) used to accomplish this. We undertook to build a prototype system to demonstrate that the Internet and the Java programming language could be used to present the real-time data conveniently. Several Java programs were developed that presented real-time data in different forms including one form that emulated the display screens of the PC GOAL system which is familiar to many at KSC. Also, we developed several communications programs to supply the data continuously. Furthermore, a framework was created using the World Wide Web (WWW) to organize the collection and presentation of the real-time data. We believe our demonstration project shows the great flexibility of the approach. We had no particular use of the data in mind, instead we wanted the most general and the least complex framework possible. People who wish to view data need only know how to use a WWW browser and the address (the URL). People wanting to build WWW documents containing real-time data need only know the values of a few parameters, they do not need to program in Java or any other language. These are stunning advantages over more monolithic systems.

Real-time Enhanced Vision System

NASA Technical Reports Server (NTRS)

Hines, Glenn D.; Rahman, Zia-Ur; Jobson, Daniel J.; Woodell, Glenn A.; Harrah, Steven D.

2005-01-01

Flying in poor visibility conditions, such as rain, snow, fog or haze, is inherently dangerous. However these conditions can occur at nearly any location, so inevitably pilots must successfully navigate through them. At NASA Langley Research Center (LaRC), under support of the Aviation Safety and Security Program Office and the Systems Engineering Directorate, we are developing an Enhanced Vision System (EVS) that combines image enhancement and synthetic vision elements to assist pilots flying through adverse weather conditions. This system uses a combination of forward-looking infrared and visible sensors for data acquisition. A core function of the system is to enhance and fuse the sensor data in order to increase the information content and quality of the captured imagery. These operations must be performed in real-time for the pilot to use while flying. For image enhancement, we are using the LaRC patented Retinex algorithm since it performs exceptionally well for improving low-contrast range imagery typically seen during poor visibility conditions. In general, real-time operation of the Retinex requires specialized hardware. To date, we have successfully implemented a single-sensor real-time version of the Retinex on several different Digital Signal Processor (DSP) platforms. In this paper we give an overview of the EVS and its performance requirements for real-time enhancement and fusion and we discuss our current real-time Retinex implementations on DSPs.

Real-time enhanced vision system

NASA Astrophysics Data System (ADS)

Hines, Glenn D.; Rahman, Zia-ur; Jobson, Daniel J.; Woodell, Glenn A.; Harrah, Steven D.

2005-05-01

Flying in poor visibility conditions, such as rain, snow, fog or haze, is inherently dangerous. However these conditions can occur at nearly any location, so inevitably pilots must successfully navigate through them. At NASA Langley Research Center (LaRC), under support of the Aviation Safety and Security Program Office and the Systems Engineering Directorate, we are developing an Enhanced Vision System (EVS) that combines image enhancement and synthetic vision elements to assist pilots flying through adverse weather conditions. This system uses a combination of forward-looking infrared and visible sensors for data acquisition. A core function of the system is to enhance and fuse the sensor data in order to increase the information content and quality of the captured imagery. These operations must be performed in real-time for the pilot to use while flying. For image enhancement, we are using the LaRC patented Retinex algorithm since it performs exceptionally well for improving low-contrast range imagery typically seen during poor visibility poor visibility conditions. In general, real-time operation of the Retinex requires specialized hardware. To date, we have successfully implemented a single-sensor real-time version of the Retinex on several different Digital Signal Processor (DSP) platforms. In this paper we give an overview of the EVS and its performance requirements for real-time enhancement and fusion and we discuss our current real-time Retinex implementations on DSPs.

Hard Real-Time: C++ Versus RTSJ

NASA Technical Reports Server (NTRS)

Dvorak, Daniel L.; Reinholtz, William K.

2004-01-01

In the domain of hard real-time systems, which language is better: C++ or the Real-Time Specification for Java (RTSJ)? Although ordinary Java provides a more productive programming environment than C++ due to its automatic memory management, that benefit does not apply to RTSJ when using NoHeapRealtimeThread and non-heap memory areas. As a result, RTSJ programmers must manage non-heap memory explicitly. While that's not a deterrent for veteran real-time programmers-where explicit memory management is common-the lack of certain language features in RTSJ (and Java) makes that manual memory management harder to accomplish safely than in C++. This paper illustrates the problem for practitioners in the context of moving data and managing memory in a real-time producer/consumer pattern. The relative ease of implementation and safety of the C++ programming model suggests that RTSJ has a struggle ahead in the domain of hard real-time applications, despite its other attractive features.

Occlusive ligature and standardized fenestration of a Baerveldt tube with and without antimetabolites for early postoperative intraocular pressure control.

PubMed

Trible, J R; Brown, D B

1998-12-01

To determine the effectiveness of a surgical modification for a nonvalved aqueous tube shunt in controlling intraocular pressure (IOP) in the early postoperative period. The effect of antimetabolite use on IOP also was studied. A retrospective study of consecutive patients who underwent modified Baerveldt 350-mm2 implant with varied, nonrandomized, exposure to antimetabolites. Fifty-one eyes of 46 patients with uncontrolled glaucoma were examined. Identical surgical modification of a Baerveldt 350-mm2 tube was performed in all cases and consisted of placement of an occlusive 7-0 polyglactin suture just anterior to the plate followed by a through-and-through penetration of the tube just anterior to the occlusive ligature with a standardized 15 degrees blade. Seventeen eyes were not exposed to antimetabolite, while 2 groups of 17 eyes had 3 minutes' episcleral exposure to either 5-fluorouracil 50 mg/ml or mitomycin C 0.4 mg/ml at the location corresponding to the fenestration. The Tenon's layer and conjunctiva were not exposed because of concerns regarding conjunctival erosion over the device. Intraocular pressure and number of antiglaucoma medications required were analyzed. For the group, mean IOP before surgery and on postoperative days 1, 4, 10, 21, 42, 63, 84, and 112 was (in millimeters of mercury) 34.6, 20.1, 17.0, 17.2, 22.0, 17.3, 18.7, 17.4, and 15.6, respectively. There was an elevation of IOP at day 21 relative to fibrotic blockage of the fenestration before suture autolysis. This was temporized with antiglaucoma medication until suture autolysis occurred or treated with laser suture lysis (8 eyes). On day 1, hypotony occurred in 3 (6%) eyes whereas IOP greater than 30 mmHg was observed in 13 (26%) eyes. By day 10, the frequency had decreased to one (2.1 %) eye and three (6.4%) eyes, respectively. The use of antimetabolites did not result in lower IOP or less medication needed for any group at any interval (analysis of variance). This modification of a

Research Directions in Real-Time Systems.

DTIC Science & Technology

1996-09-01

This report summarizes a survey of published research in real time systems . Material is presented that provides an overview of the topic, focusing on...communications protocols and scheduling techniques. It is noted that real - time systems deserve special attention separate from other areas because of...formal tools for design and analysis of real - time systems . The early work on applications as well as notable theoretical advances are summarized

Effect of caffeine on the intraocular pressure in patients with primary open angle glaucoma

PubMed Central

Chandra, Peeyush; Gaur, Ajit; Varma, Shambhu

2011-01-01

Purpose Coffee and tea are very common nonalcoholic beverages. However, their intake, particularly that of coffee, has been suggested to increase intraocular pressure (IOP) in patients with open angle glaucoma/ocular hypertension. The causative agent has been suggested to be their caffeine content. The objective of this study was to determine if this represents a direct caffeine effect. This study was therefore done using pure caffeine applied directly to the eyes. Methods The study was conducted with five human volunteers with open angle glaucoma/ ocular hypertension. IOP was measured using a Perkins applanation tonometer. Eye drops of 1% caffeine were prepared in-home. Following the initial (basal) measurement of the IOP, 50 μL of the eye drop preparation was instilled in the eye at 0-, 4-, and 6-hour intervals. IOPs were measured 30 minutes after each instillation. A second study was also undertaken following the first. In this study, the same patients instilled the eye drops three times per day for 1 week at home and then returned to the clinic on day 7. They were then again treated with caffeine eye drops as above and IOPs measured. Results In the 1-day study, the mean basal IOP was 23.6 ± 2.80 mmHg. Thirty minutes after instillation of the drops as described, the pressures were 23.2 ± 1.93, 22.2 ± 1.99, and 22.6 ± 2.31. The basal reading was taken at 10 am and another reading was then taken at 10.30 am. Additional eye drops were instilled at 2 and 8 pm and readings taken 30 minutes after each instillation. In the 1 week study, the basal value was 22.6 ± 2.32. After instillation of the drops as above the values were 23 ± 2.16, 22.4 ± 2.27, and 23 ± 1.94. Conclusion Administration of caffeine into the eyes of patients did not have any effect on IOP and it remained relatively unchanged. This was true in the 1-day study as well as in the 1-week study. A cumulative effect was not visible. The results therefore demonstrate that caffeine has no significant

Review and update of intraocular therapy in noninfectious uveitis.

PubMed

Sallam, Ahmed; Taylor, Simon R J; Lightman, Sue

2011-11-01

To review new clinically relevant data regarding the intraocular treatment of noninfectious uveitis. Triamcinolone acetonide, the most commonly used intravitreal corticosteroid for treatment of uveitis and uveitic macular oedema has a limited duration of action and is associated with a high risk of corticosteroid-induced intraocular pressure (IOP) rise and cataract. Recent advances have led to the development of sustained-release corticosteroid devices using different corticosteroids such as dexamethasone and fluocinolone acetonide. Treatment options for patients who have previously exhibited corticosteroid hypertensive response have also expanded through the use of new noncorticosteroid intravitreal therapeutics such as methotrexate and antivascular endothelial growth factor (anti-VEGF) agents. Ozurdex dexamethasone implant appears to have a better safety profile, and a slightly long-lasting effect than triamcinolone acetonide. The Retisert implant allows the release of corticosteroids at a constant rate for 2.5 years, but it requires surgical placement and its use is associated with a very high risk of cataract and requirement for IOP-lowering surgery. For patients who are steroid responders, methotrexate may offer a better alternative to corticosteroid treatment than anti-VEGF agents, but controlled trials are required to confirm this.

Real-time dynamic simulation of the Cassini spacecraft using DARTS. Part 2: Parallel/vectorized real-time implementation

NASA Technical Reports Server (NTRS)

Fijany, A.; Roberts, J. A.; Jain, A.; Man, G. K.

1993-01-01

Part 1 of this paper presented the requirements for the real-time simulation of Cassini spacecraft along with some discussion of the DARTS algorithm. Here, in Part 2 we discuss the development and implementation of parallel/vectorized DARTS algorithm and architecture for real-time simulation. Development of the fast algorithms and architecture for real-time hardware-in-the-loop simulation of spacecraft dynamics is motivated by the fact that it represents a hard real-time problem, in the sense that the correctness of the simulation depends on both the numerical accuracy and the exact timing of the computation. For a given model fidelity, the computation should be computed within a predefined time period. Further reduction in computation time allows increasing the fidelity of the model (i.e., inclusion of more flexible modes) and the integration routine.

Isoflurane and ketamine:xylazine differentially affect intraocular pressure-associated scotopic threshold responses in Sprague-Dawley rats.

PubMed

Choh, Vivian; Gurdita, Akshay; Tan, Bingyao; Feng, Yunwei; Bizheva, Kostadinka; McCulloch, Daphne L; Joos, Karen M

2017-10-01

Amplitudes of electroretinograms (ERG) are enhanced during acute, moderate elevation of intraocular pressure (IOP) in rats anaesthetised with isoflurane. As anaesthetics alone are known to affect ERG amplitudes, the present study compares the effects of inhalant isoflurane and injected ketamine:xylazine on the scotopic threshold response (STR) in rats with moderate IOP elevation. Isoflurane-anaesthetised (n = 9) and ketamine:xylazine-anaesthetised (n = 6) rats underwent acute unilateral IOP elevation using a vascular loop anterior to the equator of the right eye. STRs to a luminance series (subthreshold to -3.04 log scotopic cd s/m 2 ) were recorded from each eye of Sprague-Dawley rats before, during, and after IOP elevation. Positive STR (pSTR) amplitudes for all conditions were significantly smaller (p = 0.0001) for isoflurane- than for ketamine:xylazine-anaesthetised rats. In addition, ketamine:xylazine was associated with a progressive increase in pSTR amplitudes over time (p = 0.0028). IOP elevation was associated with an increase in pSTR amplitude (both anaesthetics p < 0.0001). The absolute interocular differences in IOP-associated enhancement of pSTR amplitudes for ketamine:xylazine and isoflurane were similar (66.3 ± 35.5 vs. 54.2 ± 24.1 µV, respectively). However, the fold increase in amplitude during IOP elevation was significantly higher in the isoflurane- than in the ketamine:xylazine-anaesthetised rats (16.8 ± 29.7x vs. 2.1 ± 2.7x, respectively, p = 0.0004). The anaesthetics differentially affect the STRs in the rat model with markedly reduced amplitudes with isoflurane compared to ketamine:xylazine. However, the IOP-associated enhancement is of similar absolute magnitude for the two anaesthetics, suggesting that IOP stress and anaesthetic effects operate on separate retinal mechanisms.

21 CFR 886.4300 - Intraocular lens guide.

Code of Federal Regulations, 2010 CFR

2010-04-01

...) MEDICAL DEVICES OPHTHALMIC DEVICES Surgical Devices § 886.4300 Intraocular lens guide. (a) Identification. An intraocular lens guide is a device intended to be inserted into the eye during surgery to direct... lenses, the device is exempt from the premarket notification procedures in subpart E of part 807 of this...

Real-Time MENTAT programming language and architecture

NASA Technical Reports Server (NTRS)

Grimshaw, Andrew S.; Silberman, Ami; Liu, Jane W. S.

1989-01-01

Real-time MENTAT, a programming environment designed to simplify the task of programming real-time applications in distributed and parallel environments, is described. It is based on the same data-driven computation model and object-oriented programming paradigm as MENTAT. It provides an easy-to-use mechanism to exploit parallelism, language constructs for the expression and enforcement of timing constraints, and run-time support for scheduling and exciting real-time programs. The real-time MENTAT programming language is an extended C++. The extensions are added to facilitate automatic detection of data flow and generation of data flow graphs, to express the timing constraints of individual granules of computation, and to provide scheduling directives for the runtime system. A high-level view of the real-time MENTAT system architecture and programming language constructs is provided.

Real Time Conference 2016 Overview

NASA Astrophysics Data System (ADS)

Luchetta, Adriano

2017-06-01

This is a special issue of the IEEE Transactions on Nuclear Science containing papers from the invited, oral, and poster presentation of the 20th Real Time Conference (RT2016). The conference was held June 6-10, 2016, at Centro Congressi Padova “A. Luciani,” Padova, Italy, and was organized by Consorzio RFX (CNR, ENEA, INFN, Università di Padova, Acciaierie Venete SpA) and the Istituto Nazionale di Fisica Nucleare. The Real Time Conference is multidisciplinary and focuses on the latest developments in real-time techniques in high-energy physics, nuclear physics, astrophysics and astroparticle physics, nuclear fusion, medical physics, space instrumentation, nuclear power instrumentation, general radiation instrumentation, and real-time security and safety. Taking place every second year, it is sponsored by the Computer Application in Nuclear and Plasma Sciences technical committee of the IEEE Nuclear and Plasma Sciences Society. RT2016 attracted more than 240 registrants, with a large proportion of young researchers and engineers. It had an attendance of 67 students from many countries.

Personalized Prediction of Glaucoma Progression Under Different Target Intraocular Pressure Levels Using Filtered Forecasting Methods.

PubMed

Kazemian, Pooyan; Lavieri, Mariel S; Van Oyen, Mark P; Andrews, Chris; Stein, Joshua D

2018-04-01

To generate personalized forecasts of how patients with open-angle glaucoma (OAG) experience disease progression at different intraocular pressure (IOP) levels to aid clinicians with setting personalized target IOPs. Secondary analyses using longitudinal data from 2 randomized controlled trials. Participants with moderate or advanced OAG from the Collaborative Initial Glaucoma Treatment Study (CIGTS) or the Advanced Glaucoma Intervention Study (AGIS). By using perimetric and tonometric data from trial participants, we developed and validated Kalman Filter (KF) models for fast-, slow-, and nonprogressing patients with OAG. The KF can generate personalized and dynamically updated forecasts of OAG progression under different target IOP levels. For each participant, we determined how mean deviation (MD) would change if the patient maintains his/her IOP at 1 of 7 levels (6, 9, 12, 15, 18, 21, or 24 mmHg) over the next 5 years. We also model and predict changes to MD over the same time horizon if IOP is increased or decreased by 3, 6, and 9 mmHg from the level attained in the trials. Personalized estimates of the change in MD under different target IOP levels. A total of 571 participants (mean age, 64.2 years; standard deviation, 10.9) were followed for a mean of 6.5 years (standard deviation, 2.8). Our models predicted that, on average, fast progressors would lose 2.1, 6.7, and 11.2 decibels (dB) MD under target IOPs of 6, 15, and 24 mmHg, respectively, over 5 years. In contrast, on average, slow progressors would lose 0.8, 2.1, and 4.1 dB MD under the same target IOPs and time frame. When using our tool to quantify the OAG progression dynamics for all 571 patients, we found no statistically significant differences over 5 years between progression for black versus white, male versus female, and CIGTS versus AGIS participants under different target IOPs (P > 0.05 for all). To our knowledge, this is the first clinical decision-making tool that generates personalized

On Time Performance Pressure

NASA Technical Reports Server (NTRS)

Connell, Linda; Wichner, David; Jakey, Abegael

2013-01-01

Within many operations, the pressures for on-time performance are high. Each month, on-time statistics are reported to the Department of Transportation and made public. There is a natural tendency for employees under pressure to do their best to meet these objectives. As a result, pressure to get the job done within the allotted time may cause personnel to deviate from procedures and policies. Additionally, inadequate or unavailable resources may drive employees to work around standard processes that are seen as barriers. However, bypassing practices to enable on-time performance may affect more than the statistics. ASRS reports often highlight on-time performance pressures which may result in impact across all workgroups in an attempt to achieve on-time performance. Reporters often provide in-depth insights into their experiences which can be used by industry to identify and focus on the implementation of systemic fixes.

Real-Time Network Management

DTIC Science & Technology

1998-07-01

Report No. WH97JR00-A002 Sponsored by REAL-TIME NETWORK MANAGEMENT FINAL TECHNICAL REPORT K CD July 1998 CO CO O W O Defense Advanced...Approved for public release; distribution unlimited. t^GquALmmsPEami Report No. WH97JR00-A002 REAL-TIME NETWORK MANAGEMENT Synectics Corporation...2.1.2.1 WAN-class Networks 12 2.1.2.2 IEEE 802.3-class Networks 13 2.2 Task 2 - Object Modeling for Architecture 14 2.2.1 Managed Objects 14 2.2.2

Real-time PCR detection chemistry.

PubMed

Navarro, E; Serrano-Heras, G; Castaño, M J; Solera, J

2015-01-15

Real-time PCR is the method of choice in many laboratories for diagnostic and food applications. This technology merges the polymerase chain reaction chemistry with the use of fluorescent reporter molecules in order to monitor the production of amplification products during each cycle of the PCR reaction. Thus, the combination of excellent sensitivity and specificity, reproducible data, low contamination risk and reduced hand-on time, which make it a post-PCR analysis unnecessary, has made real-time PCR technology an appealing alternative to conventional PCR. The present paper attempts to provide a rigorous overview of fluorescent-based methods for nucleic acid analysis in real-time PCR described in the literature so far. Herein, different real-time PCR chemistries have been classified into two main groups; the first group comprises double-stranded DNA intercalating molecules, such as SYBR Green I and EvaGreen, whereas the second includes fluorophore-labeled oligonucleotides. The latter, in turn, has been divided into three subgroups according to the type of fluorescent molecules used in the PCR reaction: (i) primer-probes (Scorpions, Amplifluor, LUX, Cyclicons, Angler); (ii) probes; hydrolysis (TaqMan, MGB-TaqMan, Snake assay) and hybridization (Hybprobe or FRET, Molecular Beacons, HyBeacon, MGB-Pleiades, MGB-Eclipse, ResonSense, Yin-Yang or displacing); and (iii) analogues of nucleic acids (PNA, LNA, ZNA, non-natural bases: Plexor primer, Tiny-Molecular Beacon). In addition, structures, mechanisms of action, advantages and applications of such real-time PCR probes and analogues are depicted in this review. Copyright © 2014 Elsevier B.V. All rights reserved.

Early changes in morphology and intraocular pressure by size of clear corneal incision.

PubMed

Cheng, Bing; Liu, Yi; Liu, Yizhi; Xie, Bin Bin; Xi, Lei; Yang, Ye

2011-06-01

We compared changes in morphology and intraocular pressure (IOP) induced by clear 2.2-mm and 3.0-mm corneal incisions in a cohort of patients with cataracts. In 160 eyes (from 70 men and 90 women at the Ophthalmic Center of Sun Yat-sen University), optical coherence tomography and tonometry were performed at 1, 5, and 24 hours after cataract surgery. The main outcome measures were IOP, postoperative changes in Descemet membrane detachment (DMD), healing of the surgical incision, and inflammation of the anterior chamber. Five hours after surgery, patients with 2.2-mm and 3.0-mm incisions had lower IOPs (P < 0.017) as measured by noncontact tonometry, but the difference was significant only among patients with grade V cataracts (2.2 mm, 12.6 ± 1.2 mm Hg; 3.0 mm, 14.5 ± 0.9 mm Hg, P < 0.05). The incidence of endothelial gap at 24 hours after surgery was significantly higher in the 2.2-mm (50%) versus 3.0-mm (11.1%) group of patients with grade V cataracts (P < 0.05). The incidence of DMD at 5 hours was also significantly higher in the 2.2-mm group (75%) than in the 3.0-mm group (22.2%) only among patients with this grade (P < 0.05). Incision width made no difference among patients with grade I-IV lens nuclei; but among those with grade V, 3.0-mm incisions had significantly less endothelial gaping, less DMD, and higher mean IOPs. For these patients, smaller incisions may not be optimal, and eyes may be especially vulnerable within 5 hours of surgery.

Intraocular pressure measurement over soft contact lens by rebound tonometer: a comparative study

PubMed Central

Nacaroglu, Senay Asik; Un, Emine Seker; Ersoz, Mehmet Giray; Tasci, Yelda

2015-01-01

AIM To evaluate the intraocular pressure (IOP) measurements by Icare rebound tonometer over a contact lens in comparison with Goldmann applanation tonometry (GAT). METHODS Fifty patients using contact lens were included in this study. One of the eyes of the patients was selected randomly and their IOP were measured by rebound tonometer with and without contact lens (RTCL, RT respectively) and by GAT, as well as their central corneal thickness (CCT) by optical pachymeter. The results of both methods were compared by correlation analysis, general linear method repeated measure and Bland-Altman analysis. RESULTS Mean IOP values measured by RTCL, RT and GAT were 15.68±3.7, 14.50±3.4 and 14.16±2.8 (P<0.001), respectively. Mean IOP by RTCL was significantly higher than the measurements implemented by RT and GAT (P<0.001), while there was no difference between the measurements by GAT and RT (P=0.629). There was a good level of positive correlation between GAT and RTCL as well as RT (r=0.786 P<0.001, r=0.833 P<0.001, respectively). We have observed that CCT increase did not show any correlation with the differences of the measurements between RTCL and RT (P=0.329), RTCL and GAT (P=0.07) as well as RT and GAT (P=0.189) in linear regression model. CONCLUSION The average of the measurements over contact lens by rebound tonometer was found to be higher than what was measured by GAT. Although this difference is statistically significant, it may be clinically negligible in the normal population. PMID:26086004

Real-Time Embedded High Performance Computing: Communications Scheduling.

DTIC Science & Technology

1995-06-01

real - time operating system must explicitly limit the degradation of the timing performance of all processes as the number of processes...adequately supported by a real - time operating system , could compound the development problems encountered in the past. Many experts feel that the... real - time operating system support for an MPP, although they all provide some support for distributed real-time applications. A distributed real

Review of the influence of pigment dispersion and exfoliation glaucoma diagnosis on intraocular pressure in clinical trials evaluating primary open-angle glaucoma and ocular hypertension.

PubMed

Stewart, William C; DeMill, D L; Wirostko, Barbara M; Nelson, Lindsay A; Stewart, Jeanette A

2013-08-01

To evaluate published, randomized, prospective, parallel clinical trials utilizing currently approved glaucoma medications to determine what influence, if any, pigment dispersion (PD) or exfoliation glaucoma (XFG) patients had on the intraocular pressure. A review of clinical trial articles evaluating currently used topical glaucoma medicines. Articles were published between January 1995 and April 2011. If the articles met the inclusion/exclusion criteria, they were analyzed for PD and XFG. Twenty-four articles were included, containing 49 treatment arms that included PD or XFG patients. The range of PD patients was 0% to 4.5%, with a mean of 1.5±0.9%, and for XFG patients 0% to 6.3%, with a mean of 2.2±2.1%. The treatment arms with PD showed a difference in the intraocular pressures (IOPs), for all studies analyzed together, for the baseline IOPs between clinical trials that did and did not include PD patients (8 AM IOPs: with PD 26.5±0.9 mm Hg and without PD 25.8±1.3 mm Hg, P=0.024; and diurnal curve mean IOPs: with PD 25.3±1.1 mm Hg and without PD 24.5±1.3 mm Hg, P=0.024). The XFG treatment arms showed that there was a difference in the IOPs for all studies analyzed together for diurnal baseline IOPs between clinical trials that did and did not include XFG patients (with XFG 25.2±1.2 mm Hg and without XFG 24.3±1.0 mm Hg, P=0.016). Trial designs for prospective, parallel, glaucoma clinical studies that are performed in the United States generally can include PD and XFG patients with only a small impact on the IOP and a low number of such subjects enrolled.

Real-Time Assessment of Mechanical Tissue Trauma in Surgery.

PubMed

Chandler, James H; Mushtaq, Faisal; Moxley-Wyles, Benjamin; West, Nicholas P; Taylor, Gregory W; Culmer, Peter R

2017-10-01

This work presents a method to assess and prevent tissue trauma in real-time during surgery. Tissue trauma occurs routinely during laparoscopic surgery with potentially severe consequences. As such, it is crucial that a surgeon is able to regulate the pressure exerted by surgical instruments. We propose a novel method to assess the onset of tissue trauma by considering the mechanical response of tissue as it is loaded in real-time. We conducted a parametric study using a lab-based grasping model and differing load conditions. Mechanical stress-time data were analyzed to characterize the tissue response to grasps. Qualitative and quantitative histological analyses were performed to inspect damage characteristics of the tissue under different load conditions. These were correlated against the mechanical measures to identify the nature of trauma onset with respect to our predictive metric. Results showed increasing tissue trauma with load and a strong correlation with the mechanical response of the tissue. Load rate and load history also showed a clear effect on tissue response. The proposed method for trauma assessment was effective in identifying damage. The metric can be normalized with respect to loading rate and history, making it feasible in the unconstrained environment of intraoperative surgery. This work demonstrates that tissue trauma can be predicted using mechanical measures in real-time. Applying this technique to laparoscopic tools has the potential to reduce unnecessary tissue trauma and its associated complications by indicating through user feedback or actively regulating the mechanical impact of surgical instruments.

Distribution and associations of intraocular pressure in 7- and 12-year-old Chinese children: The Anyang Childhood Eye Study.

PubMed

Li, Shuning; Li, Shi-Ming; Wang, Xiao-Lei; Kang, Meng-Tian; Liu, Luo-Ru; Li, He; Wei, Shi-Fei; Ran, An-Ran; Zhan, Siyan; Thomas, Ravi; Wang, Ningli

2017-01-01

To report the intraocular pressure (IOP) and its association with myopia and other factors in 7 and 12-year-old Chinese children. All children participating in the Anyang Childhood Eye Study underwent non-contact tonometry as well as measurement of central corneal thickness (CCT), axial length, cycloplegic auto-refraction, blood pressure, height and weight. A questionnaire was used to collect other relevant information. Univariable and multivariable analysis were performed to determine the associations of IOP. A total of 2760 7-year-old children (95.4%) and 2198 12-year-old children (97.0%) were included. The mean IOP was 13.5±3.1 mmHg in the younger cohort and 15.8±3.5 mmHg in older children (P<0.0001). On multivariable analysis, higher IOP in the younger cohort was associated with female gender (standardized regression coefficient [SRC], 0.11, P<0.0001), increasing central corneal thickness (SRC, 0.39, P<0.0001), myopia (SRC, 0.05, P = 0.03), deep anterior chamber (SRC, 0.07, P<0.01), smaller waist (SRC, 0.07, P<0.01) and increasing mean arterial pressure (SRC, 0.13, P<0.0001). In the older cohort, higher IOP was again associated with female gender (SRC, 0.16, P<0.0001), increasing central corneal thickness (SRC, 0.43, P<0.0001), deep anterior chamber (SRC, 0.09, P<0.01), higher body mass index (SRC, 0.07, P = 0.04) and with increasing mean arterial pressure (SRC, 0.09, P = 0.01), age at which reading commenced (SRC, 0.10, P<0.01) and birth method (SRC, 0.09, P = 0.01), but not with myopia (SRC, 0.09, P = 0.20). In Chinese children, higher IOP was associated with female gender, older age, thicker central cornea, deeper anterior chamber and higher mean arterial pressure. Higher body mass index, younger age at commencement of reading and being born of a caesarean section was also associated with higher IOP in adolescence.