Abstract
Purpose:
SDD are extracellular lesions that confer risk for AMD progression independently from drusen, yet are misclassified or omitted altogether from grading systems based on color fundus photography, including those used for genetic association studies. We determined SDD frequency and optimal imaging modality in a sample of eyes in normal macular health or with early or intermediate AMD.
Methods:
Patients ≥ 60 years old with either normal macular health or AMD were recruited from comprehensive ophthalmology clinics. Color fundus photographs, infrared (IR) and autofluorescence (AF) images, and SD-OCT volumes were obtained. Patients were stratified by the AREDS 9-step severity scale (PMID 162866100), the CARMS (PMID 16458093), and the Clinical Classification System (PMID 23332590). In each IR, SD-OCT, AF, and color image from a 96 patient convenience sample, SDD was graded as present, questionable, or absent. For each eye, a summary SDD classification considered SDD Present if present in SD-OCT and present or questionable in at least one en face modality; Questionable if questionable in SD-OCT and either questionable or absent in all en face modalities; and Absent if absent in SD-OCT and in all en face modalities. The distribution of summary classifications was determined relative to the 3 grading systems.
Results:
SDD was judged Present, Questionable, and Absent in 18 (19%), 37 (39%), and 39 (41%), respectively, of 94 imaged Right eyes, and 16 (17%), 30 (32%), 44 (47%), respectively, in 90 imaged Left eyes. When present by SD-OCT, SDD was also present in 55% more Right Eyes and 88% more Left Eyes using IR than using AF. SDD was present in 18.2-34.5% of eyes with either early or intermediate AMD, and in 4.9-20.0% of normal eyes, depending on the eye and grading system. Up to 40% of SDD evaluations were considered questionable, at all stages.
Conclusions:
This is the first examination of SDD frequency in eyes with early and intermediate AMD and those in normal macular health, all subject to imaging technologies suitable for SDD detection. IR in combination with SD-OCT revealed more eyes with SDD than AF in combination with SD-OCT.
Keywords: 412 age-related macular degeneration