Faculty Bibliography

PURPOSE: To evaluate quantitatively the effects of tinted spectacle lenses on visual performance in individuals without visual pathology. METHODS: Twenty-five subjects were assessed by measuring contrast sensitivity with and without glare. Gray, brown, yellow, green, purple, and blue lens tints were evaluated. Measurements were repeated with each lens tint and with a clear lens, and the order was counterbalanced within and between subjects. Glare was induced with a modified brightness acuity tester. RESULTS: All subjects demonstrated an increase in contrast thresholds under glare conditions for all lens tints. However, purple and blue lens tints resulted in the least amount of contrast threshold increase; the yellow lens tint resulted in the largest contrast threshold increase. CONCLUSIONS: Purple and blue lens tints may improve contrast sensitivity in control subjects under glare conditions

PURPOSE/OBJECTIVE:To examine whether a mosaic pattern of retinal dysfunction in obligate carriers of X-linked retinitis pigmentosa (XLRP) could be observed in local electroretinographic responses obtained with the multifocal electroretinogram (mfERG). DESIGN/METHODS:Prospective observational case series. PARTICIPANTS/METHODS:Five obligate carriers of XLRP (mean age, 53.2 years) were recruited into the study. METHODS:Examination of each subject included a complete ocular examination, Humphrey visual field, standard full-field electroretinogram (ERG), and mfERG testing. For the mfERG, we used a 103-scaled hexagonal stimulus array that subtended a retinal area of approximately 40 in diameter. The amplitudes and implicit times in each location for the mfERG was compared with the corresponding value determined for a group of normally sighted, age-corrected control subjects. MAIN OUTCOME MEASURES/METHODS:Mapping of 103 local electroretinographic response amplitudes and implicit times within the central 40 with the multifocal electroretinogram. RESULTS:Localized regions of reduced mfERG amplitudes and/or delayed implicit times were found in four of five carriers. In one of these four carriers, a mosaic pattern of mfERG dysfunction was present even in the absence of any clinically apparent retinal changes, retinal sensitivity losses on Humphrey field testing, or abnormal full-field cone ERG responses. However, one carrier with a typical tapetal-like reflex demonstrated no deficit on any functional tests. CONCLUSIONS:The mfERG demonstrated patchy areas of retinal dysfunction in some carriers of XLRP. This mosaic pattern of dysfunction may be observed in some patients with a normal-appearing fundus, normal psychophysical thresholds, and normal amplitude and implicit time full-field ERG cone responses.

The multifocal electroretinogram (mfERG) has been commonly used as a method for obtaining objective visual fields. Although qualitative comparisons have been good, quantitative comparisons between the results from mfERG and the results from Humphrey Visual Field Analyser (HVFA) have found variable degrees of agreement depending upon the mfERG response parameter examined and/or the disease studied. Lack of agreement may be due to differences in methodology, differences in the sites of response generation, and/or differences derived from comparing suprathreshold versus threshold responses. In addition, the two procedures are performed at different levels of adaptation. We developed an approach for matching stimulus parameters and compared mfERG and psychophysical thresholds to assess the effects of technique and level of adaptation on the two responses. Psychophysical and mfERG thresholds were obtained as a function of the adaptation level (1.5-4.0 log td) and retinal location. The derived increment threshold-versus-intensity functions for both measures were fitted using the equation logT=logT(0)+log((A+A(0))/A(0))(n). We found that the values of A(0) for the mfERG data were one log unit higher than those for the psychophysical data. In addition, the value of the slope (n) for the mfERG data was shallower (0.8) than that of the psychophysical data (1.0). Predictions were made about comparisons of HVFA threshold and mfERG amplitude data in patients with retinal disease based upon a two-site model of adaptation. The data for some groups of patients could be best-fitted with a model of a disease acting at a site distal to all gain changes, whereas data from other patients were best fitted with a model of a disease acting at a site proximal to all retinal gain. The relationship between the Humphrey visual field threshold losses and mfERG amplitude reductions depends upon the site and mechanism of a particular disease process and the model of retinal gain assumed. In no case is a one-to-one relationship between the losses in the two measures predicted

OBJECTIVE: To test the hypothesis that the retinal pigment epithelial/photoreceptor complex is affected in patients with pigment dispersion syndrome and/or in patients with pigmentary glaucoma. METHODS: Electro-oculograms were recorded from patients with pigment dispersion syndrome, pigmentary glaucoma, ocular hypertension, and primary open-angle glaucoma and from control subjects. Electro-oculograms were recorded during 15 minutes of dark adaptation followed by 15 minutes of light adaptation. For each subject, dark-trough amplitudes, dark-trough latencies, light-peak amplitudes, light-peak latencies, and ratios of the light-peak amplitude to the dark-trough amplitude (Arden ratios) were calculated. RESULTS: A 1-way analysis of variance of the Arden ratios indicated significant differences among the groups of subjects. Results of a post hoc Newman-Keuls test revealed that the mean Arden ratios of patients with pigment dispersion syndrome and patients with pigmentary glaucoma were significantly lower than the mean ratios of the controls, the patients with primary open-angle glaucoma, and those with ocular hypertension. CONCLUSIONS: The results provide support for the hypothesis that the integrity of the retinal pigment epithelial/photoreceptor complex is affected in patients with pigment dispersion syndrome and in those with pigmentary glaucoma. Congenital and/or structural abnormalities of the retinal pigment epithelial/photoreceptor complex should be considered when models of the etiology of pigment dispersion syndrome are proposed

We examined whether lateral spread of adaptation can be observed in the electroretinogram in humans. Specifically, we tested whether the luminance level of a surrounding, nonmodulated annulus affects the multifocal electroretinogram (ERG) response of a modulated central area. Multifocal electroretinograms were recorded in response to an array of 37 unscaled hexagons subtending a retinal area of 38 deg x 35 deg. Responses were recorded in six control subjects. In the first series of experiments, only the center hexagon was modulated, while the surrounding 36 hexagons were held constant at either 0.45, 172, or 340 cd/m2. In a subsequent series of control experiments, modulation depth of the center hexagon was varied and the proximity of the surrounding hexagon systematically altered. For the center-modulated condition, response amplitude and implicit time for the first-order kernel response significantly decreased as a function of increasing surround luminance. Control experiments demonstrated that the effect of the surround illumination was not due to scattered light but was influenced by the proximity of the surrounding annulus. These results demonstrate that lateral adaptation influences can be measured using the multifocal ERG

PURPOSE: To determine the correlation between the aesthetics of lens tints preferred for cosmesis and lens tints preferred for viewing. METHODS: Thirty-five subjects (mean age: 25; 49% male, 51% female) with no significant ocular pathology participated in the study. Median visual acuity was 20/20. Color vision testing was performed on each subject using Ishihara plates, and those with abnormal scores were excluded from the study. Subjects were shown nine pre-selected tinted lenses (50% transmittance) of variable wavelengths. These lenses were mounted on two separate color backgrounds, one white and the other approximating their skin tone. Subjects were asked to choose from each background which tinted lens they would most prefer to wear and which lens they would least prefer to wear. The subjects were then shown a series of eight pictures (four nature photographs and four paintings) with different dominant wavelengths. Subjects were asked to grade the aesthetic effect of a clear lens and each of the nine tinted lenses on the appearance of the pictures. Chromaticity coordinates were calculated for each lens and picture. RESULTS: The blue lens was the most frequently chosen preferred lens to wear, followed by green, purple, and gray. The least preferred lenses were yellow, brown, and pink. For viewing the nature photographs, the clear lens was preferred over any of the tinted lenses. For viewing the paintings, the purple lens was most preferred. The yellow lens was least preferred for both photographs and paintings. CONCLUSIONS: Younger individuals with no significant ocular pathology preferred viewing both nature photographs and paintings through tinted lenses that did not, or only slightly, altered the chromaticity of the image. Whereas a clear lens was favored over the tinted lenses for viewing the photographs, some tinted lenses (purple and pink) were preferred for viewing paintings. There was no correlation between the most favored lens tint chosen based purely on cosmesis and the most favored lens tint based on viewing preference. However, the least preferred lens tint for cosmesis and viewing was yellow