摘要:

Age-related maculopathy (ARM) can be considered a transition from normal retinal changes to pathological processes. It is important to recognize patients who have progressed beyond a normal state in order to provide appropriate clinical management. This pilot study considers the clinical dilemma of diagnosing and monitoring early ARM. We carried out a controlled study and tested the visual functions of 11 pre-ARM (PARM) and 11 early ARM subjects. Apart from compromised visual acuity, losses in central visual field, color vision, and visual adaptation were also recorded in our ARM subjects. We found a low contrast (LC) Amsler grid to be most sensitive to central field defects and that the desaturated panel D-15 gave too many false positives among normal elderly subjects. Our results indicate foveal sparing in early ARM and question the capacity of acuity assessment to reflect early functional changes adequately. A clinical battery is recommended to detect and monitor ARM.

ISSN:1040-5488    

出版商:OVID    

年代:1993

数据来源: OVID

摘要:

We used a new card procedure to evaluate binocular contrast sensitivity (CS) in 24- and 36-month-old children. The test consists of 40 large (50 by 28 cm) matteboard cards, each of which contains a sine wave grating with 1 of 5 spatial frequencies (0.4, 0.8,1.6, 3.2, and 4.8 cpd at 80 cm) and with 1 of 8 contrast levels [from 33% (CS=3) to 0.4% (CS=260)]. Estimates of subjects' CS to each spatial frequency were obtained with a modified forced-choice preferential looking (FPL) technique similar to that developed for the Teller Acuity Cards (TAC). All 36-month-olds and 74% of the 24- month-olds completed the entire procedure in an average of 12 min per child. For both groups, the shape of the mean constrast sensitivity functions (CSF's) resembled the characteristic inverted U shown by normal adults, except that the toddlers' functions were shifted to lower contrasts and spatial frequencies. Combined with previous results, it appears that the CS cards hold promise as a time-efficient means of assessing CS in infants and young children, and may provide the prototype for a clinical tool to help detect early visual and neurological dysfunction.

ISSN:1040-5488    

出版商:OVID    

年代:1993

数据来源: OVID

摘要:

In a random sample of 3283 subjects, 1266 right eyes and 1334 left eyes were diagnosed as having one of the following: age-related macular degeneration (ARMD), cataract, or glaucoma. In this same sample 1369 right eyes and 1312 left eyes had no ocular disease. All eyes had their contrast sensitivity measured using the Arden-type gratings manufactured by The American Optical Corporation. This is a large sample survey and although prevalence rates for the diseases examined may be inferred, this must be carried out with caution. I found for those eyes where the disease interfered with the integrity of the retina (ARMD, glaucoma) the mean contrast sensitivity scores were higher, in the middle and upper frequencies, than for those eyes with lens opacities. For frequencies above 0.4 cpd contrast sensitivities associated with diseased eyes were significantly (p < 0.001) reduced when compared to the same measures obtained on nondiseased eyes.

ISSN:1040-5488    

出版商:OVID    

年代:1993

数据来源: OVID

摘要:

In the presence of one or two intraocular lenses (lOL's; pseudophakic corrections) or in the presence of naturally occurring or developmental anisometropia (due to a tumescent cataract) some induced or residual refractive aniseikonia is usually encountered. We wish to call this problem to the attention of the optometric practitioner. We provide a discussion of the resultant aniseikonia and simple rules of thumb for management of such patients with refractive aniseikonia. Aniseikonia in these patients may be less important than once had been suggested, but certainly it is more significant than it is currently being considered. Use of personal computers to calculate this aniseikonia makes appropriate correction relatively easy and readily applicable

ISSN:1040-5488    

出版商:OVID    

年代:1993

数据来源: OVID

摘要:

We approached the question of the visual tolerance to uncorrected astigmatism by exploring the changes in the retinal diffraction images brought about by astigmatism, as a function of spherical focus. Consideration of the Rayleigh and Maréchal wavefront criteria and of the changes in ocular modulation transfer function (MTF) broadly supports a value of 0.25 DC as a practical tolerance limit for uncorrected astigmatism. This study underlines the limitations of a geometrical optical approach to this problem in particular, and shows that the concept of the circle of least confusion may be misleading.

ISSN:1040-5488    

出版商:OVID    

年代:1993

数据来源: OVID

摘要:

The angiographic characteristics of central serous chorioretinopathy (CSC) were studied by analyzing digitalized angiograms with an IMAGEnet system. We determined the type of leak, its location, and its distance from the fovea and from the center of the detachment. Round leaks were located farther from the detachment center and farther from the fovea than smokestack leaks. Detachments tended to center on the fovea regardless of the leak to fovea distance. These findings suggest that for serous detachment of the sensory retina to develop and be maintained, there must be a diffuse dysfunctional area of retinal pigment epithelium and a focal leak.

ISSN:1040-5488    

出版商:OVID    

年代:1993

数据来源: OVID

摘要:

Previous studies have shown that changes in target parameters, such as luminance, color, size, and shape exert little effect on the stability of fixation, measured as the standard deviation of eye positions over several seconds of fixation. In this study, we investigated the effect of target contrast and dioptric blur on the stability of fixation in five normal subjects. The horizontal positions of both eyes were assessed by infrared limbal tracking while the subjects fixated binocularly for 20-s intervals on a cross-shaped target at 2 m. Across subjects, the mean stability of fixation on a high contrast target worsened significantly from 8.9 to 12.0 min arc with fixation through increasing amounts (0 to 4 D) of dioptric blur. However, without blur there was no statistically significant effect on fixation stability of varying the target contrast from 7 to 84%. The variability of vergence was not significantly influenced in either condition. Like other target parameters investigated in previous studies, dioptric blur and contrast have relatively inconsequential effects on fixation stability, indicating that the signals used to control fixation are largely independent of stimulus parameters. Practically, the findings suggest that when patients' eye movements are recorded for clinical reasons, the results are unlikely to be affected seriously by the presence of residual refractive error.

ISSN:1040-5488    

出版商:OVID    

年代:1993

数据来源: OVID

摘要:

The Gunning Fog Index and the Flesch Reading Ease Formula were used to analyze the readability of a sample population of optometric and ophthalmological journals. The results suggest that ophthalmological journals are significantly less readable when compared to optometric publications. Specific findings are reported along with the limitations of the study.

ISSN:1040-5488    

出版商:OVID    

年代:1993

数据来源: OVID

摘要:

Prepresbyopic patients with reduced accommodative amplitude (accommodative insufficiency) are commonly seen in optometric practice. Treatments include accommodative therapy and plus reading lenses. We did a prospective study of the effects of vision therapy and plus reading lenses on 15 patients (mean age 21.87 ± 9.66 years) with accommodative insufficiency; presumed etiologies included head trauma (6 patients), thyroid disease (3 patients), seizures (1 patient), toxoplasmosis (1 patient), and idiopathic causes (4 patients). A 7-question scaled response pre- and posttreatment questionnaire assessed symptoms of two groups, vision therapy (idiopathic only) and progressive addition lenses (all patients). No idiopathic patient improved after 3 weeks of accommodative therapy. Progressive lenses with a near addition of +1.00 or +1.25 were then prescribed. Questionnaire results, which indicate that near additions provided more relief of symptoms than vision therapy for treatment of accommodation insufficiency, underscore the need for careful examination of prepresbyopic patients to determine those who would benefit from a near addition.

ISSN:1040-5488    

出版商:OVID    

年代:1993

数据来源: OVID

摘要:

This review discusses the role of lasers in eye care under five headings: ·Absorption of laser radiation by ocular tissues. · Types of lasers include: ruby, argon, gas, organic dye, krypton, Nd:YAG, excimer, and infrared. ·Applications of lasers for examining the eye include: laser refraction, determining visual acuity by laser fringes, measuring retinal blood flow, scanning laser ophthalmoscopy and tomography, measuring aqueous flare, ocular holography, measuring retinal absorption, measuring visually evoked potentials, and measuring corneal sensitivity. ·Applications of laser radiation for ocular surgery include: photocoagulation, destruction of tumors, reattaching the retina, treating glaucoma by producing an iridotomy or by trabeculoplasty or by cyclodestruction. Lasers can be used to remove surface irregularities or superficial opacities from the cornea or eyelids. Other uses are for producing a capsulotomy and for altering corneal curvature as a means of correcting ametropia. ·Potential adverse effects of laser radiation on the eye are summarized.

ISSN:1040-5488    

出版商:OVID    

年代:1993

数据来源: OVID