Relationship Between Rod-Mediated Sensitivity, Low-Luminance Visual Acuity, and Night Vision Questionnaire in Age-Related Macular Degeneration.

Purpose: To quantify the association between dark adaptation parameters and other clinical measures of visual function among people with and without early and intermediate age-related macular degeneration (AMD). Methods: In this cross-sectional study, participants underwent multimodal imaging and visual function testing, including best-corrected visual acuity (BCVA), low-luminance visual acuity (LLVA), low-luminance deficit (LLD = BCVA - LLVA) and the 10-item Night Vision Questionnaire (NVQ-10). Dynamic and static dark-adapted chromatic perimetry (DACP) was performed. Sensitivity difference was defined as the difference in sensitivity between the 505-nm and 625-nm stimuli. Rod intercept time (RIT) was estimated as the time required to reach a threshold of -3 log candelas/meter2 with the 505-nm stimulus following bleaching. The magnitude of association between the DACP parameters and other clinical tests was estimated via mixed-effects regression. Results: A total of 51 participants (aged 51-88 years, 65% female, 39% with AMD) were included. RIT was found to be negatively associated with BCVA (P < 0.001), LLVA (P = 0.005), and NVQ-10 score (P = 0.028) but not LLD (P = 0.763). There was no evidence of an association between sensitivity difference and any of the clinical measures (P ≥ 0.081). Conclusions: Reduced rod function, as determined by RIT, was associated with lower NVQ-10 scores (designed to interrogate rod-mediated function) and with worse BCVA and LLVA (measures of cone function). Translational Relevance: Decreasing rod function maybe indicative of more generalized photoreceptor dysfunction involving cones. Further development of questionnaires to target function in scotopic conditions may provide an easier to administer test without the need to perform perimetric tests of rod function.

Topical anaesthetic in the treatment of corneal epithelial defects: What are the risks?

BACKGROUND: Recent publications have suggested that  topical anaesthetic eye drops can be used safely and are effective in providing pain relief for the treatment of corneal abrasions. Complications resulting from the injudicious prescribing of topical anaesthetic eye drops are seen with some frequency in the Royal Victorian Eye and Ear Hospital's (RVEEH's) emergency department. OBJECTIVE: The aim of this article is to review the literature and provide a clinical perspective to challenge the safety of topical anaesthetic eye drops for corneal abrasions. DISCUSSION: The literature relevant to this clinical question is reviewed, with an emphasis on a critical evaluation of the publications in question. Cases from the RVEEH are used for illustrative purpose. An alternative option for analgesia is suggested.

Longitudinal Changes in Retinotopic Rod Function in Intermediate Age-Related Macular Degeneration.

Purpose: Although impairment of rod function in the early stages of age-related macular degeneration (AMD) has been well recognized, data on longitudinal changes in rod function at multiple retinal locations remain limited. This study investigated the longitudinal changes in retinotopic rod function in eyes with intermediate AMD (iAMD). Methods: Complete ophthalmic examination, multimodal imaging, and scotopic perimetry were performed at baseline and at 12-month follow-up. Perimetric scotopic retinal sensitivities for the 505-nm stimulus were repeatedly measured for 20 minutes after exposing to a single photobleach (∼30%). The rod intercept time (RIT) and retinal sensitivity at seven retinal loci within the central 12° were ascertained. Using the 95% limit of measurement variability derived from the control eyes as a reference, the proportion of test points with a significant change in retinal sensitivity or RIT at follow-up was determined. Results: Twenty iAMD and 6 control eyes were included. Decline in rod function was detected at 12-month follow-up in eyes with iAMD, but not in control eyes. Approximately 25% of test points in iAMD eyes showed a significant increase in RIT compared to 6% of test points with a decrease in RIT over the 12-month period (P < 0.001). Similarly, 40% of test points demonstrated a reduction in retinal sensitivity compared to the 7% of test points with an increase in retinal sensitivity at follow-up (P < 0.001). Conclusions: There are detectable retinotopic changes in rod function over 12 months in iAMD eyes, indicating an ongoing disease progression in rod impairment or loss with time.

Assessment of Retinotopic Rod Photoreceptor Function Using a Dark-Adapted Chromatic Perimeter in Intermediate Age-Related Macular Degeneration.

PURPOSE: We determine the feasibility of using a dark-adapted chromatic (DAC) perimeter to obtain dark-adapted static and dynamic rod function at multiple retinal locations, and compare these functional parameters between subjects with intermediate age-related macular degeneration (AMD) and normal controls. METHODS: Perimetric dark-adapted retinal sensitivities for the 505 and 620 nm stimuli across 7 retinal locations within the central 12° were repeatedly measured after exposing to a single photobleach in 22 intermediate AMD subjects and 8 controls. The sensitivities for each stimulus at 20 minutes after bleach and the sensitivity difference between the stimuli were used to determine static rod function. Sensitivities for the 505 nm stimulus at various times within the initial 20 minutes after bleach were used to estimate the rod criterion time to determine rod function dynamics. The static and dynamic rod functional parameters were compared between AMD and control eyes. RESULTS: Compared to the control eyes, AMD eyes had a reduction in retinal sensitivities for the 505 nm (P < 0.001) and 620 nm (P < 0.001) stimuli, a reduction in sensitivity difference (P < 0.001), and an increased in rod criterion time (P < 0.001). Region within the central 6° appeared to be the most defective and AMD eyes with reticular pseudodrusen (RPD) seemed to have worse function than eyes without RPD. CONCLUSIONS: It is feasible to use a DAC perimeter to study dark-adapted static and dynamic rod-mediated function at multiple retinal loci. Static and dynamic rod function were abnormal in intermediate AMD and more so in eyes with RPD, particularly within the central 6° retina.