Influence of white-light-emitting diodes on primary visual cortex layer 5 pyramidal neurons (V1L5PNs) and remodeling by blue-light-blocking lenses.

Studies have explored the consequences of excessive exposure to white-light-emitting diodes (LEDs) in the retina. Hence, we aimed to assess the implications of such exposure on structural alterations of the visual cortex, learning and memory, and amelioration by blue-light-blocking lenses (BBLs). Eight-week-old Wistar rats (n = 24) were used for the experiment and divided into four groups (n = 6 in each group) as control, white LED light exposure (LE), BBL Crizal Prevencia-1 (CP), and DuraVision Blue-2 (DB). Animals in the exposure group were exposed to white LED directly for 28 days (12:12-h light/dark cycle), whereas animals in the BBL groups were exposed to similar light with BBLs attached to the LEDs. Post-exposure, a Morris water maze was performed for memory retention, followed by structural analysis of layer 5 pyramidal neurons in the visual cortex. We observed a significant difference (P < 0.001) in the functional test on day 1 and day 2 of training in the LE group. Structural analysis of Golgi-Cox-stained visual cortex layer 5 pyramidal neurons showed significant alterations in the apical and basal branching points (p < 0.001) and basal intersection points (p < 0.001) in the LE group. Post hoc analysis revealed significant changes between (p < 0.001) LE and CP and (p < 0.001) CP and DB groups. Constant and cumulative exposure to white LEDs presented with structural and functional alterations in the visual cortex, which are partly remodeled by BBLs.

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.

Agreement and repeatability of Icare ic100 tonometer.

PURPOSE: To find the agreement and repeatability of Icare ic100 tonometer. METHODS: We included 150 subjects above the age of 18 years for this cross-sectional, multicenter study with intraocular pressure (IOP) ≥7 mmHg. After the initial ophthalmic examination, two masked examiners took five IOP measurements using three different instruments; Icare ic100, Icare TA01i, and Goldmann applanation tonometer (GAT) in only one eye of the participants. Comparison of agreement of IOP using different instruments was quantified with intraclass correlation coefficient (ICC) using the two-way random effects models of absolute agreement and Cronbach's alpha. The test-retest variability of the instruments was assessed by deriving repeatability coefficient (RC) and coefficient of variation (CV). RESULTS: Agreement between the tonometers across the different IOP groups had no statistically significant difference in their mean IOP. Icare ic100 was found to have good reliability across all IOP groups (ICC value >0.78) when compared with Icare TA01i. In comparison with GAT, Icare ic100 showed good reliability across all IOP groups (ICC >0.87) except >16 to <23 mmHg group where it showed moderate reliability (ICC = 0.52). Icare ic100 showed good repeatability with RC and CV of 2.67 and 4.89, respectively. CONCLUSION: Icare ic100 rebound tonometer can measure IOP with relatively small measurement error and can provide a reliable and repeatable reading in comparison with GAT across a wide pressure range without hampering corneal health.

Awareness, knowledge, and barriers to low vision services among eye care practitioners.

BACKGROUND: Eyesight plays an important role in our day today life. When the vision gets hampered, daily activities of an individual will be affected. The prevalence of visual impairment is increasing across the globe, with more burdens on the developing world. The uptake of low vision services remains to be low in developing countries like India. METHODS: A newly constructed questionnaire using information from previously conducted telephonic interviews and article search was administered among 50 eye care practitioners from Kerala, India for the pilot study. Modifications were made in the questionnaire, based on the responses obtained from the pilot study. From their responses, awareness, knowledge, and barriers for the low vision services among eye care practitioners were assessed. RESULTS: (1) Pilot study - the Cronbach's alpha values obtained for knowledge, awareness and barrier questions were 0.814, 0.297, and 0.810, respectively, and content validity index was found to be 0.64. (2) Main study - 211 eye care practitioners from 12 states of India took part in the study that accounted for a response rate of 16.7%. The participants included were 95 (45%) men and 116 (55%) women with a mean age of 28.18 ± 7.04 years. The lack of awareness was found to be the major barrier in the provision and uptake of low vision services from the practitioner's perspective. CONCLUSION: The study results showed that there is a lack of awareness among eye care practitioners about low vision services, which acts as a major barrier in the effective delivery of these services.

Virtually controlled computerised visual acuity screening in a multilingual Indian population.

INTRODUCTION: The efficacy of tele-based (virtually monitored) visual acuity (VA) examination in a hospital-based multilingual population was assessed based on subjects from the Outpatient Department of Optometry, School of Allied Health Sciences, Manipal University and Department of Ophthalmology, Kasturba Medical College, Manipal, India. METHODS: Visual acuity measurement using a computerized VA chart (COMPlog) was done using a telemethod and face-to-face method in a randomized fashion for all subjects. Virtual (remotely operated) control of examination procedure and video-conferencing helped the optometrist positioned elsewhere (different physical location) to remotely operate the COMPlog VA chart and also interact with the subjects. The connection was facilitated using Lync software connected through local area network connections. During tele-examination, instructions were given on subject's language preference (Kannada, Malayalam or English). RESULTS: Mean age of 96 subjects (three language groups) was 40.3±14.1 years and a Bland-Altman plot showed good agreement with clinically acceptable limits of agreement. The mean difference in VA between the telemethod and face-to-face method was 0.00 logMAR (±0.16), p=0.844. Two methods had good intra-class correlation (0.912, 95% confidence interval 0.868-0.941) and had good agreement across the language groups (kappa>0.7). CONCLUSIONS: Visual acuity measurements using the telemethod along with native dialect was comparable to conventional face-to-face method in a hospital-based multilingual population. Digital VA testing systems along with communication in native dialect can be effectively integrated into a tele-eyecare model.