摘要:

2Δ) than the distance heterophoria. In these subjects, proximally induced vergence may have accounted for the difference in response.

ISSN:1040-5488    

出版商:OVID    

年代:1990

数据来源: OVID

摘要:

The relation between corneal thickness changes and the Dk value of rigid contact lenses was investigated in 42 patients who were fitted with contact lenses for the first time. These 42 patients were divided into 4 groups that were fitted with contact lenses of different Dk values. Corneal thickness in the open-eye state was measured (mid-afternoon) before contact lens fitting and after 6 weeks of daily contact lens wear. The changes in corneal thickness were not significantly different among the 4 contact lens materials (Dk values 8, 26, 54, and 92). We conclude that for daily wear use the lower Dk materials meet corneal requirements. However, there is a significant trend; the higher Dk values result in a thinner cornea. Causes for this phenomenon are discussed.

ISSN:1040-5488    

出版商:OVID    

年代:1990

数据来源: OVID

摘要:

The relation between the practitioner and patient may have important effects upon the safety and success of contact lens wear. In this study we investigated the interrelations among clinicians' interpersonal communication skills and patients' motivation, satisfaction, and compliance with care and maintenance instructions. These variables were measured through questionnaires and interviews. Significant associations were found among many aspects of the clinicians' interpersonal skills and aspects of the patients' motivation and satisfaction. These findings are consistent with those from other health care settings and indicate that the quality of the contact lens practitioner's interpersonal skills can substantially influence patient outcomes and perceptions.

ISSN:1040-5488    

出版商:OVID    

年代:1990

数据来源: OVID

摘要:

Some investigators have suggested that the poor quality of vision which some spherical, single vision, soft lens-wearing patients report may be a result of spherical aberration induced in the ocular system when a soft lens is placed on the eye. In this study, the longitudinal spherical aberration of spherical soft lenses, both on and off the eye, was calculated using an aspheric corneal model and two-dimensional ray tracing program. Specifically designed front-surface aspheric, soft lenses were produced which demonstrated levels of in-air power variation similar to that calculated for similar-parameter spherically surfaced lenses. The effect of these lenses on the visual performance of nine subjects was assessed by measuring changes in contrast sensitivity and high contrast visual acuity through 3- and 6-mm artificial pupils. Significant losses of contrast sensitivity were recorded for the spherically aberrated lenses with the 6-mm pupil but not with the 3-mm pupil. High contrast acuity was not affected by any of the aberrated lenses with either the 3- or 6-mm pupils. Theoretical calculations and the contrast sensitivity results indicate that negatively powered lenses produce significantly less spherical aberration in situ than positively powered lenses. Because the majority of the prepresbyopic soft lens-wearing population have low to moderate amounts of myopia, it would appear that soft lens-induced spherical aberration is unlikely to be responsible for the reduction in visual performance which some patients report when corrected with single vision soft lenses.

ISSN:1040-5488    

出版商:OVID    

年代:1990

数据来源: OVID

摘要:

Presented here is a method for the improvement of stereopsis. It is based on covering and uncovering one eye in a particular way. A complete program for the improvement of stereopsis is described. This includes an uncovering technique, the use of an Orthofuser, and the observation of specular reflections. Examples are given which demonstrate the effectiveness of the method. Persons who are capable of stereopsis but who use it selectively or not at all in everyday life (paradoxical stereopsis) are particularly easy to cure.

ISSN:1040-5488    

出版商:OVID    

年代:1990

数据来源: OVID

摘要:

Binocular summation, defined as an increase in the binocular response compared with the monocular, occurs when the sensitivities of the two eyes are equal. We investigated the psychophysical and electrophysiological binocular response to a difference in monocular retinal illuminance. Different levels of unequal monocular sensitivities were induced by means of neutral density filters placed in front of one eye. Both studies produced similar results. In the absence of filters, maximum binocular summation was produced. With increasing difference in monocular illuminance, the binocular response decreased steadily until it reached a level below the monocular. The clinical implications of binocular inhibition, a perceptual phenomenon similar to Fechner's Paradox, are discussed.

ISSN:1040-5488    

出版商:OVID    

年代:1990

数据来源: OVID

摘要:

Two methods have been described for measuring tonic accommodation (TA) under clinical conditions. One is the near retinoscopy (NEAR) method; the other uses Nott retinoscopy as the patient views a low spatial frequency difference of Gaussian (DOG) target. The purpose of this study was to compare the TA measures made by these two procedures on a group of 6- to 14- year-old children. The data indicate that the procedures yield significantly different information.

ISSN:1040-5488    

出版商:OVID    

年代:1990

数据来源: OVID

摘要:

Various subjective procedures have been used in the past to examine the visual disorders and ocular symptoms often associated with prolonged usage of Video Display Units (VDU's). We examined visual neural performance for VDU stimuli which differed in size (14, 21, or 28 min arc), chromaticity (white, red, green, or blue), and retinal clarity, by transient pattern visually evoked potentials (t-p VEP's). Such information could prove useful in the design of electro-optical display systems that optimize visual neural performance and minimize ocular fatigue. Stimuli consisted of “monochromatic” (W, R, G, or Blue on black) and “multichromatic” (Blue/ R, Blue/G, and R/G) checkerboards with brightnessmatched chromatic elements displayed on a high resolution RGB monitor at 40 and 80 cm. The ambient lighting level was 54 lux. Group-averaged amplitudes and implicit times of t-p VEP's from 20 visually normal subjects indicated a differential neural response across target colors and three experimentally induced levels of blur. For monochromatic stimuli, the Blue/Black targets elicited t-p VEP's with the lowest amplitude, longest implicit time, and greatest sensitivity to optical defocus. Increasing the target element size reduced the VEP sensitivity to defocus across all colors except red. For multichromatic targets, Red/Green targets elicited the most vulnerable t-p VEP's. Several optical and neural explanations are given to explain these results. Implications for VDU designs are presented.

ISSN:1040-5488    

出版商:OVID    

年代:1990

数据来源: OVID

摘要:

The ability of a new alpha-adrenergic antagonist, dapiprazole, to reverse mydriasis produced by phenylephrine 2.5% or 10%, tropicamide 0.5%, and the combination of phenylephrine 2.5% and tropicamide 0.5% was investigated. A double masked crossover design was used to study both efficacy of mydriatic reversal and time course. The safety of administration was evaluated as well. Subjects were optometry students and their spouses. The results demonstrate that dapiprazole is safe and effective for reversing mydriasis produced by both concentrations of phenylephrine, and partially effective in reversing mydriasis in eyes treated with tropicamide 0.5%, alone, or in combination with 2.5% phenylephrine.

ISSN:1040-5488    

出版商:OVID    

年代:1990

数据来源: OVID

摘要:

This study was performed to determine the prevalence of Meibomian gland dysfunction (MGD) and to determine which patient profile factors might be associated with the syndrome. Patients were randomly selected, apparently normal patients presenting for routine vision examinations. Of the 398 patients for whom Meibomian gland expression was performed and a detailed history obtained, 155 patients or 38.9% exhibited MGD based on the principal clinical criterion of an absent or cloudy Meibomian gland secretion upon expression. Patient profile factors of gender, age, allergy occurrence, and contact lens wear were analyzed for correlation with MGD. Age was found to be the only significant correlating factor (positive correlation, p<0.0001).

ISSN:1040-5488    

出版商:OVID    

年代:1990

数据来源: OVID