Effect of Correcting Peripheral Refractive Errors on Retinal Sensitivity in Younger and Older Healthy Adults.

SIGNIFICANCE: Retinal sensitivity decreases with age and age-related eye diseases. Peripheral retinal sensitivity may also be compromised if the refractive correction is not optimized for peripheral vision. PURPOSE: This study aimed to determine the impact of using a peripheral refractive correction on perimetric thresholds and the influence of age and spherical equivalent on this impact. METHODS: We measured, in 10 younger (20 to 30 years) and 10 older (58 to 72 years) healthy subjects, perimetric thresholds for Goldmann size III stimulus in several test locations along the horizontal meridian of the visual field (eccentricity, 0, ±10, and ±25°), with default central refractive correction and with peripheral refractive corrections as measured with a Hartmann-Shack wavefront sensor. We used analysis of variance to determine the effect of age and spherical equivalent (between-subject variables) and eccentricity and correction method (central vs. eccentricity specific; within-subject variables) on retinal sensitivity. RESULTS: Retinal sensitivity was higher if the eyes were optimally corrected for the concerning test location (P = .008), and the effect of this peripheral correction differed between the younger and older subjects (interaction term between group and correction method: P = .02), primarily because of more myopia in the younger group (P = .003). The average improvement by applying peripheral corrections was 1.4 dB in the older subjects and 0.3 dB in the younger subjects. CONCLUSIONS: Peripheral optical correction has a variable impact on retinal sensitivity, and therefore, assessment of retinal sensitivity may be more accurate if peripheral defocus and astigmatism are corrected.

Binocular Interactions in Glaucoma Patients With Nonoverlapping Visual Field Defects: Contrast Summation, Rivalry, and Phase Combination.

Purpose: In glaucoma, visual field defects in the left and right eye may be non-overlapping, resulting in an intact binocular visual field. In clinical management, these patients are often considered to have normal vision. However, visual performance also relies on binocular processing. The aim of this study was to evaluate binocular visual functions in glaucoma patients with intact binocular visual field, normal visual acuity, and stereoscopy. Methods: We measured in 10 glaucoma patients and 12 age-similar controls: (1) monocular and binocular contrast sensitivity functions (CSF) using a modified quick CSF test to assess binocular contrast summation, (2) dominance during rivalry, and (3) contrast ratio at balance point with a binocular phase combination test. A mirror stereoscope was used to combine the left and right eye image (each 10° horizontally by 12° vertically) on a display. Results: Area under the monocular and binocular CSF was lower in glaucoma compared to healthy (P < 0.001), but the binocular contrast summation ratio did not differ (P = 0.30). For rivalry, the percentage of time of mixed percept was 9% versus 18% (P = 0.056), the absolute difference of the percentage of time of dominance between the two eyes 19% versus 10% (P = 0.075), and the rivalry rate 8.2 versus 12.1 switches per minute (P = 0.017) for glaucoma and healthy, respectively. Median contrast ratio at balance point was 0.66 in glaucoma and 1.03 in controls (P = 0.011). Conclusions: Binocular visual information processing deficits can be found in glaucoma patients with intact binocular visual field, normal visual acuity, and stereoscopy.

Retinal Contrast Gain Control and Temporal Modulation Sensitivity Across the Visual Field in Glaucoma at Photopic and Mesopic Light Conditions.

Purpose: Glaucoma affects many aspects of visual performance, including adaptation, and this may depend on ambient luminance. We determine the influence of glaucoma and luminance on temporal aspects of adaptation, specifically on contrast gain control and temporal modulation sensitivity (TMS). Methods: This case-control study included 12 glaucoma patients and 25 age-similar controls (50-70 years). Threshold perimetry was performed with a minimized testing grid (fovea and four peripheral locations). Stimuli (Goldmann size III 50 ms increment/decrement) were presented on a time-varying background with sinusoidally-modulated luminance (amplitude 60%; frequency 0-30 Hz; mean background luminance, 1 and 100 cd/m2). TMS (2.5-30 Hz) was measured in the same locations with a sinusoidally-modulated stimulus (Goldmann size IV, 334 ms) on a steady background (1 and 100 cd/m2). Results: In healthy subjects, contrast sensitivity decreased with increasing background modulation frequency and increased again at very high frequencies, indicating contrast gain control. Minimum sensitivity was located between 2.5 and 20 Hz, depending on luminance and eccentricity. In glaucoma patients, the same frequency dependency was found (P = 0.12) but with an overall reduced sensitivity (P = 1 × 10-5), independent of luminance (P = 0.20). Decrements differentiated better between glaucoma and healthy subjects than increments (P = 0.004). TMS was reduced in glaucoma (P = 5 × 10-6) across all frequencies and luminance levels, with complete loss for high frequencies at 1 cd/m2. Conclusions: Contrast gain control is largely unaffected in glaucoma, suggesting intact amacrine cell function. Perimetry with decrements or a high-frequency stimulus on a low-luminance background seems best to differentiate between glaucoma and healthy subjects.

The colors of paintings and viewers' preferences.

One hypothesis to explain the aesthetics of paintings is that it depends on the extent to which they mimic natural image statistics. In fact, paintings and natural scenes share several statistical image regularities but the colors of paintings seem generally more biased towards red than natural scenes. Is the particular option for colors in each painting, even if less naturalistic, critical for perceived beauty? Here we show that it is. In the experiments, 50 naïve observers, unfamiliar with the 10 paintings tested, could rotate the color gamut of the paintings and select the one producing the best subjective impression. The distributions of angles obtained are described by normal distributions with maxima deviating, on average, only 7 degrees from the original gamut orientation and full width at half maximum just above the threshold to perceive a chromatic change in the paintings. Crucially, for data pooled across observers and abstract paintings the maximum of the distribution was at zero degrees, i.e., the same as the original. This demonstrates that artists know what chromatic compositions match viewers' preferences and that the option for less naturalistic colors does not constrain the aesthetic value of paintings.

Assessing the effects of dynamic luminance contrast noise masking on a color discrimination task.

The aim of this work was to assess the influence of dynamic luminance contrast noise masking (LCNM) on color discrimination for color normal and anomalous trichromats. The stimulus was a colored target on a background presented on a calibrated CRT display. In the static LCNM condition, the background and target consisted of packed circles with variable size and static random luminance. In the dynamic LCNM condition, a 10 Hz square luminance signal was added to each circle. The phase of this signal was randomized across circles. Discrimination thresholds were estimated along 20 hue directions concurrent at the color of the background. Six observers with normal color vision, six deuteranomalous observers, and three protanomalous observers performed the test in both conditions. With dynamic LCNM, thresholds were significantly lower for anomalous observers but not for normal observers, suggesting a facilitation effect of the masking for anomalous trichromats.