... Accession Number : ADA186818. Title : A-Scan Ultrasound Measurement of Ocular Changes during Accommodation. Descriptive ...

and visual accommodation - with 382 pilbts, divided into four groups which ..... If the ascents are rapid, the gases dissolved in the humors change from ...

... studies revealed accommodation disturbances in all of the patients noted, other ocular disturbances in many, including diplopia, eg, in 22.6%. ...

A dynamic model of ocular accommodation is used to simulate the stability and dynamic performance of accommodating intraocular lenses (A-IOLs) that replace the hardened natural ocular lens that is unable to change focus. Accommodation simulations of an older eye with A-IOL materials having ...

Eccentric photorefraction is an optical technique used to assess static and/or dynamic changes in ocular focus (accommodation), ocular alignment (vergence) and pupil size. In this paper, we have developed and tested an offline application namely the dynamic photorefraction system (DPRS) which allows an accurate analysis of ...

Head and eye movements, together with ocular accommodation enable us to explore our visual environment. The stability of this environment is maintained during saccadic and vergence eye movements due to reduced contrast sensitivity to low spatial frequency information. Our recent work has revealed a new type of selective reduction of contrast sensitivity to ...

The author presents characteristics of refraction in 67 children and adolescents suffering from diabetes mellitus. The state of accomodative function of the eyes was studied in 39 schoolchildren with spherical refraction. Accomodation was found to be reduced in diabetic schoolchildren, this being connected with a prolonged course of the main disease. PMID:683963

Accommodation and vergence are two ocular motor systems that interact during binocular vision. Independent measurement of the response dynamics of each system has been achieved by the application of optometers and eye trackers. However, relatively few devices, typically earlier model optometers, allow the simultaneous assessment of ...

PURPOSE: To describe a new technique for viewing and measuring the lens diameter during accommodation. METHODS: The accommodative lens activity, in a young female carrier of ocular albinism, was evaluated using retro-illumination infrared video photography and pixel unit measurements. RESULTS: Right and left lens diameter measurements ...

PURPOSE: To assess the relationship and respective contribution of ocular higher-order aberrations (HOAs) on residual accommodative performance in presbyopic patients. PATIENTS AND METHODS: We enrolled 20 patients (40 eyes) without ophthalmological pathology, between 48 and 58 years old, with a best-corrected visual acuity more than 10/10. Total ...

This study investigated the changes in ocular aberrations that occur over the entire lens equatorial diameter during accommodation in iridectomized rhesus monkey eyes to understand the nature of accommodative lenticular deformation. Accommodation was centrally stimulated to a range of different response amplitudes ...

Previous studies have suggested that targets illuminated by monochromatic (narrow-band) light are less effective in stimulating the eye to change its focus than are black�white (broadband) targets. The present study investigates the influence of target spectral bandwidth on the dynamic accommodation response in eight subjects. The fixation target was a 3.5-cycle?deg ...

Refilling the lens capsule while preserving capsular integrity offers the potential to restore ocular accommodation. There are two persisting problems in capsular bag refilling for possible clinical application: Leakage of the injectable material through the capsular opening and capsular opacification. Numerous attempts for solving these cardinal problems ...

A Shack-Hartmann wavefront sensor was modified to allow measurement of ocular aberrations in downward gaze with binocular fixation. Subjects first performed a control task prior to four different trials involving a distance task or a near task (accommodative demand of 2.5 D) performed in primary and downward gaze (25�). Immediately after beginning and ...

The purpose of this study is to determine if cues within the blurred retinal image due to the Stiles�Crawford (SC) effect and the eye�s monochromatic aberrations can drive accommodation with a small pupil (3 mm) that is typical of bright photopic conditions.The foveal, psychophysical SC function (17 min arc) and ocular monochromatic aberrations were ...

Previous research has shown that ocular accommodation tends to correspond to an intermediate distance, the dark focus, in the absence of effective stimulation. The present experiments measured accommodative responses in the presence of two adequate, monocular stimuli superimposed optically at different distances. In Experiment I, ...

Xylopia aethiopica, African guinea pepper, is an angiosperm belonging to the family Annonecae, and used mainly as spice and in traditional medicine. The ocular dynamics of bolus consumption of 300 mg total dose was undertaken on visually active volunteers with a view to finding its ocular effects or complications. Results showed that the aqueous extract of ...

The purpose of this study was to evaluate some of the methods used to calculate objective refractions from wavefront aberrations, to determine their applicability for accommodation research. A wavefront analyzer was used to measure the ocular aberrations of 13 emmetropes and 17 myopes at distance, and 4 near target vergences: 2, 3, 4, and 5 D. The ...

Experiments were undertaken to understand the relationship between dynamic accommodative refractive and biometric (lens thickness (LT), anterior chamber depth (ACD) and anterior segment length (ASL=ACD+LT)) changes during Edinger�Westphal stimulated accommodation in rhesus monkeys. Experiments were conducted on three rhesus monkeys (aged 11�5, 4�75 ...

Experiments were undertaken to understand the relationship between dynamic accommodative refractive and biometric (lens thickness (LT), anterior chamber depth (ACD) and anterior segment length (ASL=ACD+LT)) changes during Edinger-Westphal stimulated accommodation in rhesus monkeys. Experiments were conducted on three rhesus monkeys (aged 11.5, 4.75 and ...

1. We examined the functional morphology of the intra-ocular muscles of the grey squirrel using pharmacological and histological methods. Using sympathomimetic (phenylephrine) and parasympathomimetic (carbachol) agents, administered by transcorneal iontophoresis, the response of the iris sphincter and dilator muscles and the ciliary muscle were recorded. Measurement techniques ...

1. We examined the functional morphology of the intra-ocular muscles of the grey squirrel using pharmacological and histological methods. Using sympathomimetic (phenylephrine) and parasympathomimetic (carbachol) agents, administered by transcorneal iontophoresis, the response of the iris sphincter and dilator muscles and the ciliary muscle were recorded. Measurement techniques ...

The lens capsule is a modified basement membrane that completely surrounds the ocular lens. It is known that this extracellular matrix is important for both the structure and biomechanics of the lens in addition to providing informational cues to maintain lens cell phenotype. This review covers the development and structure of the lens capsule, lens diseases associated with ...

ObjectiveInstability of ocular alignment may cause surgeons to delay surgical correction of childhood esotropia. We investigated the stability of ocular alignment over 18 weeks in children with infantile esotropia (IET), acquired non-accommodative esotropia (ANAET), or acquired partially-accommodative esotropia ...

This article discusses three largely unrecognized aspects related to fluid movement in ocular tissues; namely, a) the dynamic changes in water permeability observed in corneal and conjunctival epithelia under anisotonic conditions; b) the indications that the fluid transport rate exhibited by the ciliary epithelium is insufficient to explain aqueous humor production; and c) ...

PurposeAccommodation results in increased lens thickness and lens surface curvatures. Previous studies suggest that lens biometric accommodative changes are different with pharmacological and voluntary accommodation. In this study, refractive and biometric changes during Edinger-Westphal (EW) and pharmacologically stimulated ...

Analysis and applications of vision correction via accommodating intraocular lens (AIOL) are presented. By Gaussian optics, analytic formulas for the accommodation rate function (M) for two-optics and three-optics systems are derived and compared with the exact numerical results. In a single-optics AIOL, typical value of M is (0.5-1.5) D/mm, for an IOL ...

The human ocular lens is a tissue capable of changing its shape to dynamically adjust the optical power of the eye, a function known as accommodation, which gradually declines with age. This capability is the response of the lens tissue to external forces, which, in turn, is modulated by the biomechanical characteristics of lens tissues. In order to ...