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Results for “ACCOMMODATION, OCULAR”

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At least 649 records · Page 36Linked to original sources
PubMed1995

Varifocal contact lenses for the correction of presbyopia.

A Nissel +1.75 D PS45 lens' label power seems to be made up of about +0.75 D distance and +0.75 D near addition. There are individual variations which will depend on pupil size, corneal shape, lens position and ocular aberrations. When a +0.75 Bausch & Lomb U3 lens was used as a control, there was also a significant increase in 'accommodation' measured (+0.75 D), but this could not be explained. When two other lenses with an aspheric surface were studied, they also showed a near addition effect. In this supplementary study the changes were explained by changes in spectacle accommodation. A lens with two spherical surfaces did not show the expected increase in spectacle accommodation. Astigmatism, as a general rule, was not corrected by the PS45 lens, although the very occasional case did show some reduction. Visual acuity and contrast sensitivity at 8 cpd and 3 cpd were not significantly affected when compared to the control lens.

Accommodation, Ocular↗
PubMed1976

Miotic drugs: a review of ocular, visual, and systemic complications.

Cholinergic drugs and anticholinesterases have caused ocular complications including cataracts, iris cysts, retinal detachment, iritis, increased intraocular tension, allergic and toxic reactions, and hypermia. The visual complications include accommodative spasm; myopia and reduced visual acuity; changes in vision sensitivity, dark adaptation, and visual fields; and discomfort. The systemic complications are those common to cholinergic drugs and anticholinesterases. This review is intended as a ready reference to the drugs that cause such effects and source material.

Accommodation, Ocular↗
PubMed1989

Computer eyestrain.

Main ocular mechanisms probably underlying eyestrain symptoms in computer users-diminished aqueous tears, extraocular muscle fatigue, color fatigue and decreased amplitude of accommodation induced by monochromatic light--are discussed. With this background, some practical consequences are drawn to avoid or reduce eyestrain.

Accommodation, Ocular↗
PubMed1997

[Correlation analysis between visual acuity and sitting postural parameters of young students].

The relationship between failing eyesight and the sitting posture of young students while studying was studied quantitatively. Among the 19 students who participated in this study, 9 were classified as emmetropic and 10 were myopic. The mean age was 13.2 +/- 2.2 (mean +/- standard deviation) years. Viewing distance, neck angle, viewing angle, vertical gaze direction, and ocular surface area while studying were measured from the lateral and frontal view images of video recordings of the posture. Viewing distance, accommodative power, neck angle, viewing angle, near point, and log transformed visual acuity showed significant differences between these two groups (p < 0.001). Viewing distance of myopes (15.0 +/- 1.9 cm) (mean +/- standard desviation) is shorter than that of emmetropes (30.2 +/- 4.1 cm). Accommodative power of myopes was lower than that of emmetropes. Correlation analysis revealed that the viewing distance of students significantly correlates to neck angle, viewing angle, accommodative power, near point, and visual acuity (p < 0.01). It can be surmised that the failing eyesight of young students results from postural problems such as shortness of viewing distance and increased neck flexion.

Accommodation, Ocular↗
PubMed2002

Ocular symptoms in children treated with human-mouse chimeric anti-GD2 mAb ch14.18 for neuroblastoma.

Unusual ocular symptoms observed during intravenous treatment with anti-disialoganglioside antibody (Ab) in children suffering from neuroblastoma were analyzed and the results reported. Within the framework of the German Collaborative Neuroblastoma Study NB97, 85 children with high-risk neuroblastoma received anti-GD2 monoclonal antibody ch14.18 intravenously. Side effects were regularly reported to the study center. Ocular symptoms were recorded in clinical detail, duration and development over time. Symptoms of a parasympathetic deficit corresponding to internal ophthalmoplegia, i.e. mydriasis and accommodation deficit, were found in 10 patients. They were uni- or bilateral, began after the termination of Ab infusion and improved or disappeared in all surviving children. They did not reappear or worsen upon repeated Ab infusions. The pathophysiology of these disorders remains poorly understood. It is concluded that during systemic treatment with the anti-GD2 antibody ch14.18, reversible symptoms of parasympathetic denervation of the eye may occur which, however, do not warrant termination of this treatment.

Accommodation, Ocular↗
PubMed1996

The M1 muscarinic antagonist pirenzepine reduces myopia and eye enlargement in the tree shrew.

PURPOSE: To determine the efficacy of the M1-selective muscarinic antagonist, pirenzepine, in preventing experimentally induced myopia in a mammalian model, the tree shrew. METHODS: Tree shrews were monocularly deprived (MD) using translucent goggles or negative lenses for a period of 12 days. In two of the MD groups, tree shrews received daily subconjunctival administration of either pirenzepine (17.7 mumol; n = 9) or vehicle control (n = 6). Control groups (n = 6) were used to assess the effects of MD, injection regimen, and drug effects. RESULTS: In sham-injected and saline-injected MD tree shrews, 12 days of MD produced-13.2 D +/- 0.8 D and -14.1 D +/- 0.5 D of axial myopia, respectively. In pirenzepine-injected MD tree shrews, 12 days of MD induced an axial myopia of only -2.1 D +/- 1.4 D. The significant reduction in myopia in pirenzepine-injected MD tree shrews was caused by significantly less vitreous chamber elongation of the deprived eye (0.05 mm +/- 0.04 mm) relative to the contralateral control eye when compared to sham-injected and saline-injected MD tree shrews (0.24 mm +/- 0.02 mm and 0.29 mm +/- 0.01 mm). Mean equatorial enlargement and increased eye weight were prevented in pirenzepine-injected MD tree shrews (P < 0.01). Pirenzepine also was found to reduce myopia and ocular enlargement in lens defocus-induced myopia. Control experiments demonstrated that pirenzepine did not cause a significant reduction in amplitude of carbachol-induced accommodation. CONCLUSIONS: Findings demonstrate that chronic administration of the M1-selective muscarinic antagonist, pirenzepine, prevents experimentally induced myopia in this mammalian model by a nonaccommodative mechanism.

Accommodation, Ocular↗
PubMed1993

Chromatic aberration and ocular focus: Fincham revisited.

Longitudinal chromatic aberration of the eye (LCA) produces "color fringes" at edges that specify focus. Fincham [(1951) British Journal of Ophthalmology, 35, 381-393] concluded that these chromatic effects were important for accommodation, but most investigators disagree. We monitored accommodation in 25 subjects while they viewed a sinusoidally moving target (1.5-2.5 D at 0.2 Hz) in a Badal optometer. The target was monochromatic (590 nm with 10 nm bandwidth), or white (3000 K) with LCA normal, neutralized or reversed. Sensitivity to the effects of LCA is profound and widespread. Gain decreases substantially and phase-lag increases when LCA is eliminated, and reversing the aberration severely disrupts accommodation. The ordered arrangement of spectral foci produced by LCA seems to be a fundamental aspect of the stimulus for "reflex" accommodation.

Accommodation, Ocular↗
PubMed1985

An unusual ocular presentation of multiple sclerosis.

An unusual presentation of visual loss in multiple sclerosis is reported. The case is also noteworthy because the patient's presenting complaint appeared to be the result of insufficient or fatiguing accommodation. Had an unsuspected visual loss not been detected, the patient's management may have been inappropriate until more debilitating symptoms of the underlying cause became apparent.

Accommodation, Ocular↗
PubMed2001

Compensation of corneal aberrations by the internal optics in the human eye.

The objective was to study the relative contribution of the optical aberrations of the cornea and the internal ocular optics (with the crystalline lens as the main component) to overall aberrations in the human eye. Three sets of wave-front aberration data were independently measured in the eyes of young subjects: for the anterior surface of the cornea, the complete eye, and internal ocular optics. The amount of aberration of both the cornea and internal optics was found to be larger than for the complete eye, indicating that the first surface of the cornea and internal optics partially compensate for each other's aberrations and produce an improved retinal image. This result has a number of practical implications. For example, it shows the limitation of corneal topography as a guide for new refractive procedures and provides a strong endorsement of the value of ocular wave-front sensing for those applications.

Accommodation, Ocular↗
PubMed2000

The effect of L-arginine on intraocular pressure in the human eye.

PURPOSE: L-Arginine, a non-toxic amino acid, is converted to nitric oxide (NO) by NO synthase. Recent findings have demonstrated that NO serves as an ocular hypotensive agent. The objectives of the present study were to clarify the effect of L-arginine on intraocular pressure (IOP), pupil size, refraction and accommodative amplitude in human eyes, and to examine whether L-arginine is converted to NO in vivo. METHODS: Fourteen volunteers received an intravenous drip-infusion of 100 ml of L-arginine (10.0 g) solution. IOP levels were measured before, during and after infusion using Goldmann applanation tonometry. Pupillary diameter, refraction and accommodative amplitude were also measured in human subjects. In rabbits, the nitrite levels in the aqueous humor were measured during L- or D-arginine infusion. RESULTS: The mean IOP of the L-arginine group was significantly decreased during infusion, but recovered rapidly after infusion. The mean IOP of the control group increased during infusion. The changes in pupillary diameter, refraction, and accommodative amplitude before and after infusion of L-arginine were not significant. L-Arginine significantly elevated the level of nitrite in the aqueous humor compared with the controls. CONCLUSIONS: These findings demonstrated that L-arginine lowers IOP mainly through the formation of NO.

Accommodation, Ocular↗
PubMed2006

Factors affecting sensory functions after successful postoperative ocular alignment of acquired esotropia.

PURPOSE: We sought to evaluate the sensory status of patients with acquired esotropia who were able to re-establish stable alignment by optical correction and surgery and to determine the possible predictors of the different sensory outcomes. METHODS: Thirty-four successfully aligned esotropic patients were included in the study. Preoperative evaluation comprised history taking, measurement of visual acuity, evaluation of the sensory status (using the Worth 4-Dot test, and the Titmus Stereo test), measurement of ocular deviation, cycloplegic refraction, and fundus examination. All patients underwent successful surgical alignment to within 10 prism diopters (Delta) of orthotropia. At each postoperative follow-up visit, the sensory functions and ocular alignment were assessed. Statistical analysis of the results was performed. RESULTS: Among the 34 patients included in the study, 62% achieved fusion, 17% had diplopia, 15% had suppression, and 6% had a variable response to the Worth 4-Dot test at 6 months after surgery. Stereopsis was achieved in 32% as determined by the Titmus Stereo test. Statistical analysis revealed a significant relationship between the sensory status and the duration of strabismus (P=.00002), the age at surgery (P=.00289), and postoperative ocular alignment (P=.02211). CONCLUSION: Early surgical and optical ocular alignment of strabismic patients is advisable to achieve fusion and stereopsis.

Accommodation, Ocular↗