To compare gradings of lesions associated with age-related macular degeneration(AMD) from digital and stereoscopic film images.
Instrument validation study.
Sixty-two subjects (124 eyes) with varying degrees of AMD, includingno AMD.
Images of the optic disc and macula were taken using a 45° digitalcamera (6.3 megapixels) through dark-adapted pupils and pharmacologicallydilated pupils. In addition, 30° stereoscopic retinal film images weretaken through pharmacologically dilated pupils of the same eyes. All imageswere graded for drusen size, type, and area; pigmentary abnormalities; geographicatrophy; and neovascular lesions using the modified Wisconsin Age-RelatedMaculopathy Grading System. Exact agreement and unweighted κ scores werecalculated for paired gradings resulting from digital and film images.
Main Outcome Measure
Agreement between gradings obtained from stereoscopic slide transparenciesand digital nonstereoscopic images.
Exact agreement between gradings of digital and stereoscopic film imagestaken through pharmacologically dilated pupils was 91% (κ = 0.85)for the categories of none, early AMD, and late AMD. Exact agreement for gradingsof digital images taken through dark-adapted pupils compared with gradingsof film images was 80% (κ = 0.69). Exact agreement for gradingsof digital images captured through dark-adapted and pharmacologically dilatedpupils was 86% (κ = 0.78). In addition, κ scores for agreementbetween different approaches for individual lesions were moderate to almostperfect.
Gradings resulting from high-resolution digital images, especially whenthe pupil is pharmacologically dilated, are comparable with those resultingfrom film-based images. We conclude that digital imaging of the retina isuseful for epidemiological studies of AMD.