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Mariela C Aguilar, Alex Gonzalez, Cornelis Rowaan, Carolina P De Freitas, Karam AlRahman Alawa, Heather Ann Durkee, Alejandro Arboleda, Florence Cabot, Potyra R Rosa, Byron L Lam, Jean-Marie A Parel; Longitudinal Ocular Photosensitivity Assessment of Healthy and Achromatopsic Subjects. Invest. Ophthalmol. Vis. Sci. 2016;57(12):622.
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© ARVO (1962-2015); The Authors (2016-present)
Achromatopsia is a genetic disorder characterized by decreased vision, discomfort when exposed to light, and an inability to differentiate color. The purpose of this study was to determine the stability and reliability of the Ocular Photosensitivity Analyzer (OPA) using healthy subjects over time and whether there is a significant change in photosensitivity thresholds over time in achromatopsic subjects.
The OPA generates a light stimulus using 210 white LEDs mounted on a bi-cupola concave surface providing varying light intensity in logarithmic ascending and descending steps ranging from 0 to 4.51 log(lux) (1 to 32,000 lux). The subject is instructed to indicate whether the light stimulus is uncomfortable by pressing a hand-held button and the photosensitivity threshold is calculated after 10 response reversals. Catch trials were programmed into the OPA software to ensure the subjects’ response reliability throughout the test. Power output and irradiance were measured to ensure the OPA meets safety exposure limits set forth by the ISO standard for ophthalmic instruments.Nine healthy (5 females and 4 males, age = 31.4±7.6 years) and four achromatopsic subjects (2 females and 2 males, age = 10.5±4.4 years) were tested under an IRB approved protocol. Photosensitivity of healthy and achromatopsic subjects were measured at 0, 2, 12, 40, and 379 days and at 0, 6 and 12 months, respectively. A one-way analysis of variance was performed within each of the subject groups to determine significance in the photosensitivity thresholds between time points.
The mean photosensitivity threshold up to 379 days for healthy subjects was 3.27±0.13 log(lux). No significant change was noted for healthy subjects (p=0.98), demonstrating the reliability of the OPA. The mean photosensitivity threshold between 0 and 12 months for achromatopsic subjects was 0.48±0.52 log(lux). Despite the larger standard deviation, the change in the photosensitivity thresholds for achromatopsic subjects was not significant (p= 0.71) within 12 months.
The OPA is a safe and reliable instrument to perform longitudinal determinations of the photosensitivity thresholds in subjects. Healthy and achromatopsic subjects demonstrated no significant change in photosensitivity thresholds at varying time points. Ongoing studies are being performed with this system to increase our subject population and further validate our findings.
This is an abstract that was submitted for the 2016 ARVO Annual Meeting, held in Seattle, Wash., May 1-5, 2016.
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