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Color fundus photography (CFP) has been widely used in clinical practice as well as in research and population screening. CFP is an effective imaging modality to document changes in the posterior pole (Fig. 1). Montage of several images capturing the periphery of the retina can further provide the basis for assessment of the periphery of the retina (Fig. 2). Early Treatment Diabetic Retinopathy Study (ETDRS) 7-standard field 35-mm 30° stereoscopic CFP has been widely accepted as the gold standard for evaluation of severity of diabetic retinopathy (DR). Based on CFP, the severity of DR can be determined by grading the degree of the following lesions according to the modified Airlie House classification [1]: hemorrhages, microaneurysms (MAs), intraretinal microvascular abnormalities, venous beading, cotton wool spots, hard exudates, retinal thickening, neovascularization, preretinal hemorrhage, vitreous hemorrhage, and traction retinal detachment. A combination of ETDRS field 1 (centered on disc) and field 2 (centered on fovea) has been adopted for population screening of DR [2]. Subsequent studies have reported good to excellent agreement between film and digital images in determining DR severity.

Fig. 1. Color fundus photography of an eye with proliferative diabetic retinopathy. Image centered on fovea (a) shows neovascularization at the disc (NVD; arrows) as well as areas of dot and blot hemorrhages and hard exudates. NVD can be seen more clearly on the image centered on the disc (b).

Fig. 2. Montage of color photographs to document posterior pole as well as peripheral retina. In this montage of an eye with severe nonproliferative diabetic retinopathy, widespread dot, blot, and flame hemorrhages, as well as cotton wool spots can be seen. Intraretinal microvascular abnormality can be seen in the nasal retina (arrow).

High-quality stereoscopic CFP has also been widely used to assess the severity of age-related macular degeneration (AMD), typically using modifications of the Wisconsin AMD grading system [3]. This method has been employed in many population-based studies around the world, including the Beaver Dam and Blue Mountains Eye Studies [4]. Features assessed include drusen characteristics as well as pigmentary changes for early AMD, whereas signs of pigment epithelial detachment (PED), choroidal neovascularization (CNV), and geographic atrophy are the key features assessed for late AMD (Fig. 3). Detailed grading of early AMD features of drusen characteristics based on CFP, include drusen size (usually graded categorically as small <63 μm; ≥63 and <125 μm; ≥125 and <250 μm; ≥250 μm), drusen border (distinct vs. indistinct), characteristics (soft, calcified, or reticular), plus total drusen area. In longitudinal studies, drusen area and drusen size were identified as important indicators of AMD progression [5, 6].

Fig. 3. Color fundus photography of any eye with age-related macular degeneration. Extensive drusen of variable sizes, some confluent, can be seen throughout the macula. An area of geographic atrophy can also be seen (arrow), characterized by the well-circumscribed round shape within which the underlying choroidal vessels can clearly be seen.