Objective: To compare gradings of lesions associated with age- related macular degeneration (AMD) from digital and stereoscopic film images. Design: Instrument validation study. Participants: Sixty- two subjects (124 eyes) with varying degrees of AMD, including no AMD. Methods: Images of the optic disc and macula were taken using a 45° digital camera (6.3 megapixels) through dark- adapted pupils and pharmacologically dilated pupils. In addition, 30° stereoscopic retinal film images were taken through pharmacologically dilated pupils of the same eyes. All images were graded for drusen size, type, and area; pigmentary abnormalities; geographic atrophy; and neovascular lesions using the modified Wisconsin Age- Related Maculopathy Grading System. Exact agreement and unweighted κ .scores were calculated for paired gradings resulting from digital and film images. Main Outcome Measure: Agreement between gradings obtained from stereoscopic slide transparencies and digital nonstereoscopic images. Results: Exact agreement between gradings of digital and stereoscopic film images taken through pharmacologically dilated pupils was 91% (κ .=0.85) for the categories of none, early AMD, and late AMD. Exact agreement for gradings of digital images taken through dark- adapted pupils compared with gradings of film images was 80% (κ .=0.69). Exact agreement for gradings of digital images captured through dark- adapted and pharmacologically dilated pupils was 86% (κ =0.78). In addition, κ scores for agreement between different approaches for individual lesions were moderate to almost perfect. Conclusions: Gradings resulting from high- resolution digital images, especially when the pupil is pharmacologically dilated, are comparable with those resulting from film- based images. We conclude that digital imaging of the retina is useful for epidemiological studies of AMD.
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