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At least 415 records · Page 23Linked to original sources
PubMed1984

Spatial contrast sensitivity. Importance of controlling the patient's visibility criterion.

Clinical spatial contrast sensitivity measurements are typically made using psychophysical methods that do not specify the response criterion being used by the patient in judging grating visibility. Results of this report show the necessity of such methods for (1) maximizing detectability of early contrast sensitivity deficits by minimizing normal sample variance, and (2) ensuring that changes in an individual's contrast sensitivity reflect changes in vision and not simply fluctuations in the patient's criterion for judging grating visibility.

Adult↗
PubMed1984

Mechanisms of visual loss in corneal edema.

Although visual disability from corneal edema is a well-recognized clinical finding, it is not easily confirmed by routine visual assessment. A more reliable assessment of visual changes resulting from corneal edema of varying origins is achieved by measurement of changes in the contrast sensitivity function. The measurements can be sensitized by the presence of a glare source to allow a more accurate determination of the nature of the visual loss. Even in the absence of a measurable loss of visual acuity, corneal edema leads to diminished visual function. The magnitude and type of this loss is dependent on the origin of the edema and the site of the corneal response.

Corneal Diseases↗
PubMed1985

Effectiveness of a pinhole method for visual acuity screening.

Visual acuity screening was performed in the home in an adult population, using a standardized, retroilluminated chart. A pinhole disk was utilized to retest those subjects who initially failed the screening. All subjects failing the screening with the pinholes, and an equal number of age-matched subjects passing the screening (controls), were asked to have a complete ophthalmologic examination, including a protocol refraction in an eye clinic (clinic examination). Without use of the pinhole disk, 14.4% of subjects failed to read a 20/40 line. Use of the pinholes reduced the failure rate to 6.9%. Fifty-seven percent of those failing and 55% of controls had the clinic examination. Determination of best-corrected visual acuity after protocol refraction in the clinic indicated that the false-positive rate (the percentage of subjects who failed the screening but had visual acuity of 20/40 or better on the clinic examination) for the screening was 26%, and the false-negative rate (the percentage of subjects who passed the screening but had visual acuity of worse than 20/40 on the clinic examination) was 1.5%. Use of a pinhole disk is highly effective for visual acuity screening, reducing the false-positive rate by more than half.

Adult↗
PubMed1985

Rod saturation perimetry. Testing of the cone function with achromatic objects.

Restriction of the visual fields in bright illumination and return of the peripheral field in lower illumination were the main complaints of a 59-year-old woman with slowly progressive cone dysfunction and normal rod function. She had normal central visual acuity, normal central color vision, and normal visual fields when tested with the standard Goldmann perimeter. A large ring scotoma was demonstrated in both of her eyes, using tangential perimetry employing a white background of 85% reflection and test objects darker than the background. Using a background of 250 candelas/sq m, which caused a complete saturation of the rod function, the scotoma was absolute. Black test objects of 5% reflection were not seen.

Color Perception↗
PubMed1988

Contrast sensitivity in age-related macular degeneration.

Low-contrast charts were used to investigate the possibility that patients with drusen have visual deficits not detected by standard Snellen charts. We compared performance on Regan letter charts between 52 eyes with drusen and Snellen acuity of 20/20 and 27 control eyes. The drusen group read fewer letters than the control group on all of the charts tested. This difference increased as the contrast of the charts decreased. The loss of performance on all of the Regan charts correlated with drusen severity. Twenty-one eyes with drusen and normal Snellen acuity also were tested with a Ginsburg contrast sensitivity chart and compared with age-matched normal controls. The results showed a loss of contrast sensitivity at high spatial frequencies and a loss of peak contrast sensitivity with increasing drusen severity. These results suggest that in patients with drusen, low-contrast charts may be useful for measuring visual loss not detected by standard Snellen charts.

Adult↗
PubMed1989

Visual, refractive, and keratometric results of radial keratotomy. Five-year follow-up.

This article presents five-year findings on the first 156 radial keratotomies in our series. Results are compared with findings on these same eyes at one and three years and with results from other studies. Follow-up at five years was on 123 eyes (79%). Before surgery, the mean spherical equivalent was -5.0 diopters (D). Five years after surgery, the mean change in the spherical equivalent was 5.17 D, and 53% of eyes were within 1 D of emmetropia. Uncorrected visual acuity was 20/200 or worse in 96% of eyes before surgery. At five years, 36% had 20/20 acuity or better, and 75% were 20/40 or better. Best corrected acuity was at least 20/20 in 90% of eyes before surgery. At five years, 85% retained at least 20/20 best corrected acuity. Although some patients still have shown refractive and visual acuity changes through five years after surgery, the overall group has been stable.

Adult↗
PubMed1990

Blindness and visual impairment in an American urban population. The Baltimore Eye Survey.

Data on the prevalence of blindness and visual impairment in multiracial urban populations of the United States are not readily available. The Baltimore Eye Survey was designed to address this lack of information and provide estimates of prevalence in age-race subgroups that had not been well studied in the past. A population-based sample of 5300 blacks and whites from east Baltimore, Md, received an ophthalmologic screening examination that included detailed visual acuity measurements. Blacks had, on average, a twofold excess prevalence of blindness and visual impairment than whites, irrespective of definition. Rates rose dramatically with age for all definitions of vision loss, but there was no difference in prevalence by sex. More than 50% of subjects improved their presenting vision after refractive correction, with 7.5% improving three or more lines. Rates in Baltimore are as high or higher than those reported from previous studies. National projections indicate that greater than 3 million persons are visually impaired, 890,000 of whom are bilaterally blind by US definitions.

Adult↗
PubMed1991

Superior oblique myokymia. Quantitative characteristics of the eye movements in three patients.

Using the magnetic search coil technique, we measured horizontal, vertical, and torsional rotations of both eyes of two patients with idiopathic superior oblique myokymia, and of the affected eye in a third patient. Superior oblique myokymia was strictly monocular and consisted of an initial intorsion and depression of the affected eye and subsequent oscillations with torsional and vertical components. The peak-to-peak torsional and vertical amplitudes of the oscillations were less than 1 degree, but peak velocities frequently exceeded 4 degrees/sec in both planes. Fourier analysis indicated two features: (1) a broad range of frequencies up to about 50 Hz, indicating irregular oscillations; and (2) a superimposed larger-amplitude oscillation in the range from 1.5 to 6 Hz. Taken with electromyographic data from other studies, these results indicate that superior oblique myokymia reflects spontaneous discharge of trochlear motor neurons that have undergone regenerative changes.

Adult↗
PubMed1992

Assessment of visual acuity via a telephone interview.

We compared the visual acuity of 89 patients obtained via a telephone interview with visual acuity elicited from the same patients in an ophthalmologist's office. Agreement within one line of vision between the telephone interview, in which patients used a modified Rosenbaum near card with attached patch, and the clinic near vision test was observed in 91% of eyes, while agreement within one line of vision between the telephone interview and clinic distance vision test was found in 86% of eyes. We conclude that testing visual acuity via a telephone interview is a potentially useful approach to assessment of visual acuity and prevalence of visual impairment in the larger population.

Adult↗
PubMed1992

Binocular fusion and stereopsis associated with early surgery for monocular congenital cataracts.

Despite improved visual acuity results in infants undergoing early surgery for monocular congenital cataracts, virtually all reports indicate a lack of binocular vision and the presence of strabismus in these patients. We report herein the presence of motor fusion and stereopsis in patients who have undergone early surgery for monocular congenital cataracts. Of 13 patients with congenital cataracts who were operated on by age 9 weeks, five (38%) had essentially straight eyes and evidence of motor fusion with a minimum of 1 year of follow-up. Three (60%) of five patients demonstrated sensory fusion, two with Titmus testing and one with Randot Stereo Acuity (Stereo Optical Co Inc, Chicago, Ill) of 250 seconds of arc. We conclude that binocular fusion and stereo visual acuity are obtainable in patients with monocular congenital cataracts.

Cataract↗
PubMed1993

Validity and interpretation of Amsler grid reports.

OBJECTIVE: To compare the reports of scotomas and metamorphosia in standard and threshold Amsler grid testing with the location and extent of scotomas in the macular region as determined by standard and threshold fundus perimetry. DESIGN: Fundus perimetry determined the existence, size, and retinal location of macular scotomas. Amsler grid testing was performed with the scanning laser ophthalmoscope and the TA-300 system (Stereo Optical, Chicago, Ill). All testing was done at both standard and threshold light conditions. PATIENTS: Fifty-five patients with vision loss in the macular region and 10 normally sighted subjects. RESULTS: Nearly half of the standard and threshold scotomas were not detected by Amsler grid testing. For scotomas of 6 degrees or less in diameter, 77% of standard and 87% of threshold scotomas were not detected by Amsler grid testing. Of the eyes with central scotomas involving the fovea, 66% used an eccentric preferred retinal locus for fixating the center of the grid. Finally, more than half of the distortion reported in Amsler grids was at the retinal area that corresponded to the scotoma area, not a nonscotoma retinal area. CONCLUSION: Amsler grid reports have poor validity and cannot be accurately interpreted for use in the clinical diagnosis of retinal defects.

Adolescent↗
PubMed1993

A screening test for integrative visual dysfunction in Alzheimer's disease.

OBJECTIVE: To develop a screening test to help ophthalmologists detect visually symptomatic patients with as yet undiagnosed Alzheimer's disease. DESIGN: Administration of a battery of tests consisting of items modified from existing psychometric materials to decrease examination time and increase ease of scoring. PARTICIPANTS: Fourteen patients with Alzheimer's disease and prominent visual symptoms; 53 control subjects matched to the patients with Alzheimer's disease for age, sex, and educational level; and 22 patients with subnormal visual acuity or visual fields who did not have Alzheimer's disease. RESULTS: The novel battery of tests distinguished all 14 visually symptomatic patients with Alzheimer's disease from patients without Alzheimer's disease and control subjects. CONCLUSION: This battery of tests should enhance the ophthalmologic detection of Alzheimer's disease.

Aged↗
PubMed1993

Examination methods for glaucoma prevalence surveys.

OBJECTIVE: To perform a pilot evaluation of new examination methods for the detection of glaucoma and other causes of visual impairment in rural East Africa. DESIGN: Testing was performed by local eye nurses after a brief training course. Two novel tests of visual function were used, a scotopic sensitivity test and a visual field test performed on a laptop computer. The optic disc was examined with direct ophthalmoscopy after pupillary dilation and compared with standard photographs on a laminated card. Intraocular pressure was measured with a hand-held, electronic tonometer. SETTING: Rural Tanzania. PARTICIPANTS: One hundred twenty adult villagers. RESULTS: The visual function tests could be performed on more than 90% of subjects, and the results were correlated with the size of the optic disc cup, an objective measure of glaucoma injury. CONCLUSIONS: This survey shows the practicality of instrument-based testing of visual function under field conditions.

Adult↗
PubMed1994

Visual field profile of optic neuritis. One-year follow-up in the Optic Neuritis Treatment Trial.

PURPOSE: The purpose of this present study was to evaluate longitudinal visual field information for 448 patients over their first year of follow-up in the Optic Neuritis Treatment Trial. METHODS: We reviewed 6536 automated static visual fields performed on a visual field analyzer (Humphrey Visual Field Analyzer) at nine visits within the 1-year period for each of the patients. RESULTS: The median values of the mean deviations for affected eyes were as follows: -22.88 dB at baseline, -1.94 dB at 6 months, and -1.62 dB at 1 year. At 6 months, 51% of affected eye visual fields were normal, and at 1 year 55.9% were normal. Approximately two thirds (68.8%) of the fellow eyes were classified as abnormal at baseline, although the defects were generally slight. One third (33.2%) were abnormal at 6 months, and approximately one third were still abnormal at 1 year. More than 87% of those abnormal at 6 months and at 1 year had been abnormal at baseline. Binocular analysis revealed that 13.2% of patients showed a chiasmal or retrochiasmal type of field defect at least once during the year (5.1% bitemporal; 8.9% homonymous). Of the patients who showed a retrochiasmal visual field defect, 75.7% had an abnormal magnetic resonance imaging scan at baseline compared with 46% of the rest of the patients in the Optic Neuritis Treatment Trial (chi 2 = 10.73, df = 1, P < .002). CONCLUSION: Over the first year of follow-up, the majority of patients with visual field defects from acute optic neuritis returned to normal, as measured by automated static perimetry. Many fields showed variation in the pattern and location of the sensitivity loss. Chiasmal and retrochiasmal defects occurred more commonly than previously reported.

Acute Disease↗
PubMed1995

Visual disturbance secondary to clomiphene citrate.

OBJECTIVE: To identify a distinctive constellation of persistent visual abnormalities secondary to treatment with clomiphene citrate. DESIGN: Description of the clinical findings in three patients with visual disturbance secondary to clomiphene treatment. SETTING: A neuro-ophthalmology referral center. PATIENTS: Three women aged 32 to 36 years treated for infertility with clomiphene for 4 to 15 months. RESULTS: All three patients experienced prolonged afterimages (palinopsia), shimmering of the peripheral field, and photophobia while undergoing treatment with clomiphene. The results of the neuro-ophthalmologic examination and electrophysiologic studies were normal in all three patients. Unlike previously reported cases, visual symptoms did not resolve on cessation of treatment. Patients remain symptomatic from 2 to 7 years after discontinuing treatment with the medication. CONCLUSIONS: Treatment with clomiphene can cause prolonged visual disturbance. Patients who develop such symptoms should be advised that continued administration may cause irreversible changes. Women with characteristic visual symptoms should be questioned about past use of clomiphene.

Adult↗
PubMed1995

Grating visual acuity with Teller cards compared with Snellen visual acuity in literate patients.

OBJECTIVE: To determine the usefulness of Teller Acuity Cards for detecting three levels of vision deficit, the cutoff for amblyopia (20/40 or poorer), vision impairment (20/70), or legal blindness (20/200). DESIGN: We compared grating visual acuity with the Teller cards with Snellen visual acuity (our gold standard) in 69 literate patients with amblyopia or other cause of vision loss in a prospective masked study. RESULTS: Teller card visual acuity and distance Snellen visual acuity correlated significantly (r = .508, P < .001); however, Teller card visual acuity explained only 26% of the variation in distance Snellen visual acuity. Teller card visual acuity had a low sensitivity for detecting vision deficit of 20/40 or poorer (58%), vision deficit of 20/70 or poorer (39%), or legal blindness (24%), but somewhat more accurately reflected near Snellen visual acuity than distance visual Snellen acuity. Teller cards had a higher positive predictive value--80% for 20/70 visual acuity and 43% for legal blindness, as determined by near Snellen visual acuity. Specificity of Teller cards was 88% for detecting visual acuity loss of 20/70 and 98% for legal blindness. Negative predictive value of Teller cards for detecting visual acuity loss of 20/70 was 50% and for legal blindness was 71%. CONCLUSIONS: Teller Acuity Cards may underestimate the presence of amblyopia of all types, legal blindness, and a specified level of vision impairment (20/70). Even in the presence of normal visual acuity measurements with Teller cards, significant visual loss as assessed by standard Snellen optotypes may be anticipated in many patients.

Adolescent↗