Table 1. The retinal image quality classification system^a.

Retinal image	Good (acceptable)	Fair (acceptable)	Poor
Posterior pole	Good focus, illumination, and exposure of disk center image; optic disk and the vessels in circular area up to at least 3 disk diameters from edge of disk in all 4 quadrants are clearly observed	Reasonable focus, illumination, and exposure of disk center image; apresence of artifacts may obscure parts of disk center image so that vessels within circular region of 3 disk diameters surrounding disk cannot be visualized clearly in one or more quadrants	Unable to visualize vessels within circular region of 3 disk diameters surrounding disk in all 4 quadrants
Temporal retina Nasal retina Superior retina Inferior retina	Good focus, illumination, and exposure; vascular components, presence or absence of pathology, and avascularity can be ascertained with certainty in peripheral retina of the image	Reasonable focus, illumination and exposure; presence of artifacts may obscure some parts of peripheral retina; not all peripheral vascular components, pathology, and avascularity can be determined with certainty	Unable to visualize vessels, pathology, or avascular areas in retinal periphery

^aA single category of acceptable consisting of “good” and “fair” images was used in this analysis.