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Muneeswar Gupta Nittala, David G Birch, Dwight Stambolian, Srinivas R Sadda; Scotopic and Mesopic Retinal Sensitivity in Age-Related Macular Degeneration in an Amish Population. Invest. Ophthalmol. Vis. Sci. 2016;57(12):48.
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© ARVO (1962-2015); The Authors (2016-present)
Dark adaptation and scotopic function abnormalities are thought to be early findings is some patients with AMD. In this study, we evaluated retinal sensitivity by scotopic and photopic microperimetry (MP1) in subjects with age-related macular degeneration (AMD) in an elderly Amish population.
Mesopic and scotopic microperimetry was performed in 107 eyes of 66 elderly (age>50) Amish subjects from Pennsylvania between August 2013 and August 2015. Microperimetry (MP-1S; Nidek Technologies) was performed using a macular grid with 32 stimulus points. A 2.0 log unit neutral density filter was introduced to perform scotopic microperimetry following 30 minutes of dark adaptation. Along with MP1, all subjects underwent complete ophthalmic examinations, including spectral domain optical coherence tomography (SD-OCT) with both a Cirrus OCT (512x128 Macular Cube, Carl Zeiss Meditec, Dublin, CA, USA) and a Spectralis HRA+OCT (97 B-scan, 6x6mm, ART= 15) Heidelberg Engineering, Heidelberg Germany), fundus autofluorescence, infrared reflectance imaging, and flash color fundus photography. All images were graded at the Doheny Image Reading center by certified graders to identify subjects with evidence of AMD as defined by the Beckman classification, and to quantify drusen volume (Cirrus Advanced RPE analysis). Retinal sensitivity between subjects with and without AMD was compared.
Of the 107 eyes from 66 subjects, 31 eyes from 17 subjects had evidence of early or intermediate AMD. The mean age of the subjects with AMD was 74.86 years compared with 65.07 years in the elderly subjects without AMD. Scotopic retinal sensitivity was significantly lower (mean ± SD; 15 ± 3 dB, P = 0.007) in subjects with AMD compared to normal subjects (18 ± 3 dB). Similarly, mesopic sensitivity was also significantly lower (18 ± 3 dB, P = 0.008) in subjects with AMD (19 ± 0.5 dB), but the magnitude of the difference was small, and likely not clinically relevant. There was no significant correlation between retinal sensitivity and drusen volume.
In an elderly Amish population, eyes with early and intermediate AMD show a greater reduction in scotopic retinal sensitivity than photopic retinal sensitivity, suggesting that rod function is more severely affected than cone function.
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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