摘要:

ABSTRACTUsing forced vergence fixation disparity curves, proximal vergence was analyzed in two asymptomatic patient samples; 20 young adults (average age 25.2 ± 4.71 years) and 20 presbyopes (average age 61.6 ± 7.8 years). Total proximal vergence was significantly larger when measured under binocular (closed loop) conditions than monocular (open loop) conditions for pre-presbyopes (binocular 10.51 ± 4.7 vs. 6.4 ± 3.84 monocular) and presbyopes (binocular 11.59 ± 3.13 vs. 4.71 ± 2.15 monocular). Associated proximal vergence was shown to predict associated phoria magnitude in presbyopes and in pre-presbyopes when vergence adaptation and convergence accommodation (CA/C) interactions with accommodative convergence (AC/A) are included. A vergence/accommodation model is presented which includes influences of proximal vergence. Clinical implications of the findings relating to diagnosis and therapy are discussed.

ISSN:0093-7002    

出版商:OVID    

年代:1985

数据来源: OVID

摘要:

ABSTRACTThe magnification of the fundus image with various forms of funduscopy in ametropia and aphakia is poorly understood. This paper investigates these relationships. Direct and indirect ophthalmoscopy and biomicroscopic funduscopy is included. The Gullstrand Simplified Schematic Eye is modified by changing either the axial length, the power of the cornea, or the index of refraction of the lens to produce ametropia. Aphakia is produced by considering these same eyes with the crystalline lens removed. The magnification of these various eye/funduscope systems is presented, along with general principles illustrated by the figures.

ISSN:0093-7002    

出版商:OVID    

年代:1985

数据来源: OVID

摘要:

ABSTRACTConventional fixation disparity was compared with the corresponding fovea) fixation misalignment measured by a recently developed method based on the effect of retinal eccentricity on the width of the border enhancement band. Unlike procedures using binocular nonius alignment, the method is not subject to adaptive changes in perceived direction. Forced convergence and divergence stimulation served as the independent variable. It was found that conventional fixation disparity rep-resents only a small, constant fraction of the misalignment through the greater portion of the vergence range. However, when the misalignment is restricted to a small, central portion of the foveola, this relation changes drastically, and the fixation disparity can then be much larger than the fixation misalignment. During perfect fixation alignment of the foveal centers, there is always a significant amount of fixation disparity present. It is suggested that the large differences between fixation disparity and fixation misalignment are due to a fundamental, perceptual mechanism that is always at work during binocular vision, changing the relation between retinal location and perceived visual direction.

ISSN:0093-7002    

出版商:OVID    

年代:1985

数据来源: OVID

摘要:

ABSTRACTElectroretinograms (ERG's) and visual evoked potentials (VEP's) were recorded from four cynomolgus monkeys in response to a sinusoidally flickering argon laser beam (514 nm) producing a 50-μm spot on the fovea. Superposition of a 20-Hz train of six pulses of Qswitched (120 ns) frequency-doubled neodymium laser light (532 nm) at “safe” exposure energies in 250 ms had no significant effects on the ERG (p > 0.05). The VEP was disrupted significantly (p < 0.001) but demonstrated recovery within 500 ms of the initial pulse. There-fore, flash effects of pulsed visible lasers at these doses on suprathreshold luminance processing are probably limited only to the exposure period.

ISSN:0093-7002    

出版商:OVID    

年代:1985

数据来源: OVID

摘要:

ABSTRACTTwenty-seven subjects having vitreous asteroid bodies were matched for age and sex with control subjects. The results of random blood glucose analysis and 2-hr glucose tolerance tests were used to determine the presence of diabetes mellitus or impaired glucose tolerance. Five of the subjects having asteroid bodies were diabetic and four had impaired glucose tolerance. In the control group there were no diabetics; however, three subjects had impaired glucose tolerance. These results con-firm that a relation exists between the occurrence of vitreous asteroid bodies and diabetes mellitus (p = 0.036). There was no statistically significant difference between random blood glucose levels of the two cohorts. Four of the five diabetics were excluded from the 2-hr glucose tolerance tests; however, for the remainder of the asteroid body group, there was no significant difference in the results of this test compared with the control group. These results suggest that the relation between asteroid bodies and diabetes may not be de-pendent on blood glucose levels. Diabetics having asteroid bodies may form a special subgroup of the disease in which there is accelerated degeneration and mineralization of collagen associated with increased intraocular vascular permeability.

ISSN:0093-7002    

出版商:OVID    

年代:1985

数据来源: OVID

摘要:

ABSTRACTVisual function and ocular structures were evaluated in a family with retinitis pigmentosa (RP) by dark adaptometry, electroretinography (ERG), perimetry, and fundus photography. All members examined showed gross rod dysfunction by dark adaptometry and ERG. The inferior and nasal segments of each patient's retina showed denser accumulations of pigment than the other segments. All patients showed superior field losses, the extent of which was correlated with the age and sex of the individual. The clinical impression formed from the assessment of visual fields in this sample was that males are more severely affected than females.

ISSN:0093-7002    

出版商:OVID    

年代:1985

数据来源: OVID

摘要:

ABSTRACTVisual acuity and reading performance of 178 partially sighted patients from a rehabilitation center were measured using a TV text display device. A linear relation was demonstrated between visual acuity and reading speed for patients with visual acuity values below 15% of the normal value. With respect to reading performance, three groups of partially sighted patients could be distinguished: (1) 25% of the patients are unable to read visually and require tactile reading aids; (2) 50% are partially sighted and require high-magnification electronic reading aids; (3) 25% can read normal text by using optical magnifying devices. There is evidence that reading performance is related to the nature of the underlying ocular problem, such as refractive anomalies, macular degeneration, or other diseases.

ISSN:0093-7002    

出版商:OVID    

年代:1985

数据来源: OVID

摘要:

ABSTRACTIntraocular pressures (IOP's) were measured using the Digilab Pneuma-tonometer with the subject in both the sitting and supine positions. The IOP with the Pneuma-tonometer was greater (17.03 mm Hg) in the supine position than in the sitting position (12.90 mm Hg). The IOP measured with the Pneuma-tonometer, with the subject sitting, was similar to the IOP measured with the Goldmann applanation tonometer (13.42 mm Hg). Inasmuch as IOP tends to be lower with the patient in a sitting position, the clinician should be alert to the possibility that some patients with borderline Goldmann IOP's may have pressures well above the normal range when they are lying down. Due to the continuous recording provided by the Pneuma-tonometer, the ocular pulse pressure can be measured. We found a mean ocular pulse pressure amplitude of 1.77 mm Hg. All values are shown plus or minus 1 SD. Comparison of the ocular pulse pressure amplitude for the two eyes could aid in detecting patients with suspected carotid artery stenosis.

ISSN:0093-7002    

出版商:OVID    

年代:1985

数据来源: OVID

摘要:

ABSTRACTOn the basis of routine clinical findings taken on a group of 100 patients serving as subjects in the Houston Myopia Control study, a three-way comparison was made between retinoscopy, subjective, and Dioptron Nova refractive findings. Retinoscopy and subjective findings compared very favorably, mean differences being –0.01 D for spherical equivalent power and –0.05 D for cylinder power. Dioptron and retinoscopy findings differed by –0.30 D for spherical equivalent power and –0.13 D for cylinder power, whereas Dioptron and subjective findings differed by –0.33 D for spherical equivalent power and –0.18 D for cylinder power.

ISSN:0093-7002    

出版商:OVID    

年代:1985

数据来源: OVID

摘要:

ABSTRACTExtended wear lenses (Scanlens 75) +4.25 to –10.00 D were worn monocularly by 19 patients for an average of 5.4 years. The other eye of each patient was either emmetropic or amblyopic and no lens was worn. Both eyes were tested after lens removal and again 2 days and 7 days later. No significant differences in refraction, keratometry, or visual acuity were found between the experimental and control eyes. The amount of changes in both groups was not clinically significant: refractive changes averaged less than 0.37 D, keratometric changes averaged an equivalent 0.25 D, astigmatism increases were less than 0.25 D, and visual acuity was fully correctible to previous best visual acuity with spectacles in all cases.

ISSN:0093-7002    

出版商:OVID    

年代:1985

数据来源: OVID