Abstract
Visual light sensitivity (VLS) is a common subjective symptom found in many conditions including retinal disorders such as achromatopsia, retinitis pigmentosa, and stargardt’s macular dystrophy as well as neurologic disorders such as migraines and traumatic brain injuries. The pathophysiologic basis of VLS is poorly understood and treatment is often difficult. Associated features of VLS may include light-induced glare or dazzle, involuntary blinking squeezing or closure of the eyelid, and discomfort or pain in the eyes or/and head. Afferent light inputs arise from the rod, cone, and melanopsin photoreceptors in the retina and light stimulation may lead to pain from stimulation of the trigeminal nerve. For conditions where VLS is a prominent feature, quantitation of VLS is particularly important to understand the stage or severity of the diseases, to monitor disease progression, and to evaluate the efficacy of a treatment. Despite a common subjective symptom, quantitative studies in VLS are scarce. The objective of this study is to quantify ocular photosensitivity symptoms and light sensitivity threshold in healthy of different age group and retinal disease subjects. For the healthy cohort, I measured the intra-individual light aversion variability in 35 subjects to obtain normative values. For the retinal disease cohort, I measured the intragroup and intergroup light aversion variability in 24 retinal disease subjects with achromatopsia, retinitis pigmentosa, or stargardt’s disease. To quantify VLS, I used an automated photosensitivity tester to determine the light intensity threshold of the VLS and designed a questionnaire consisting of eight questions to assess the presence and severity of VLS symptoms. I recruited and enrolled these study subjects under detailed clinical and ophthalmic evaluations. All subjects underwent testing that included complete eye examination, visual acuity, fundus examination, and visual light sensitivity assessments in two visits, four weeks apart between April 2015 and August 2016. To the best of my knowledge, this could be the first quantitative VLS study on retinal disease subjects. The finding suggests that this novel approach demonstrated to be a sensitivity, reproducible, and reliable tool for detecting and quantifying VLS symptoms and threshold in an individual. It has ease in clinical use as a potential outcome measure in clinical trials as more treatment strategies are being tested for hereditary retinal disorders.