Blue-Light-Blocking Lenses Ameliorate Structural Alterations in the Rodent Hippocampus.

Evidence suggests that prolonged blue-light exposure can impact vision; however, less is known about its impact on non-visual higher-order functions in the brain, such as learning and memory. Blue-light-blocking lenses (BBLs) claim to reduce these potential impacts. Hence, we assessed structural and functional hippocampal alterations following blue-light exposure and the protective efficacy of BBLs. Male Wistar rats were divided into (n = 6 in each group) normal control (NC), blue-light exposure (LE), and blue-light with BBLs (Crizal Prevencia, CP and DuraVision Blue, DB) groups. After 28 days of light exposure (12:12 light: dark cycle), rats were trained for the Morris water maze memory retention test, and brain tissues were sectioned for hippocampal neuronal analysis using Golgi and Cresyl violet stains. The memory retention test was significantly delayed (p < 0.05) in LE compared with DB groups on day 1 of training. Comparison of Golgi-stained neurons showed significant structural alterations, particularly in the basal dendrites of hippocampal neurons in the LE group, with BBLs significantly mitigating these structural changes (p < 0.05). Comparison of Cresyl-violet-stained neurons revealed significantly (p < 0.001) increased degenerated hippocampal neurons in LE rats, with fewer degenerated neurons in the CP lens group for CA1 neurons (p < 0.05), and for both CP and DB groups (p < 0.05) for CA3 neurons. Thus, in addition to documented effects on visual centers, high-level blue-light exposure also results in degeneration in hippocampal neurons with associated behavioral deficits. These changes can be partially ameliorated with blue-light-blocking lenses.

A Comparison of the Visual Field Parameters of SITA Faster and SITA Standard Strategies in Glaucoma.

PURPOSE: To compare the visual field (VF) parameters of the new Swedish Interactive Thresholding Algorithm (SITA), SITA Faster (SFR) with that of SITA Standard (SS) on the Humphrey Field Analyzer. METHODS: Ninety-seven eyes of 97 subjects (63 glaucoma, 26 glaucoma suspects, and 8 normal eyes) underwent VF examination with SFR and SS strategies on the same day in random order. Agreement in VF parameters between SFR and SS strategies was assessed by Bland and Altman plots. In addition, some subjects underwent a second VF examination with SFR strategy to evaluate its test-retest variability. RESULTS: The median test duration of SS strategy was 6 minutes 14 seconds, whereas SFR was 2 minutes 49 seconds (55% shorter, P<0.001). Median mean deviation (-7.3 vs. -7.6 dB, P=0.73) and VF index (88 vs. 88%, P=0.32) were similar between the 2 strategies, whereas pattern standard deviation was significantly higher (4.8 vs. 4.7 dB, P=0.01) with SS strategy. Overall average threshold sensitivity and Garway-Heath sector-wise threshold sensitivities were similar between the 2 strategies except for the nasal sector where SFR strategy had higher sensitivity (26 vs. 25 dB, P=0.02). Bland-Altman plots showed the mean difference in all VF parameters between the SS and SFR strategies were small (ranging from -1.0 dB for the nasal sector to -0.01 dB for superotemporal sector sensitivity). The test-retest variability of VF parameters with SFR strategy was low. CONCLUSIONS: VF parameters with SFR showed good agreement with that of SS strategy. This, combined with low test-retest variability, suggests that SFR can be considered for diagnosis and monitoring of glaucoma.

Customized, automated stimulus location choice for assessment of visual field defects.

PURPOSE: To introduce a perimetric algorithm (gradient-oriented automated natural neighbor approach [GOANNA]) that automatically chooses spatial test locations to improve characterization of visual field (VF) loss without increasing test times. METHODS: Computer simulations were undertaken to assess the performance of GOANNA. GOANNA was run on a 3° grid of 150 locations, and was compared with a zippy estimation by sequential testing (ZEST) thresholding strategy for locations in the 24-2 test pattern, with the remaining 98 locations being interpolated. Simulations were seeded using empirical data from 23 eyes with glaucoma that were measured at all 150 locations. The performance of the procedures was assessed by comparing the output thresholds to the input thresholds (accuracy and precision) and by evaluating the number of presentations required for the procedure to terminate (efficiency). RESULTS: When collated across whole-fields, there was no significant difference in accuracy, precision, or efficiency between GOANNA and ZEST. However, GOANNA targeted presentations on scotoma borders; hence it was more precise and accurate at locations where the sensitivity gradient within the VF was high. CONCLUSIONS: Compared with ZEST, GOANNA was marginally less precise in areas of the VF that had spatially uniform sensitivity, but improved accuracy and precision in regions surrounding scotoma edges. GOANNA provides a principled framework for automatic placement of additional test locations to provide spatially denser testing around the borders of VF loss.