Table 3.

Definition of overall image quality for all images from a given eye

Image quality	Definition
Good	Focus and clarity are sufficient for grading of all features to be completed
	Retinal details (small capillaries) are sharply defined and have crisp boundaries. It should be possible to see the ends of the larger vessels approaching the foveal avascular zone (FAZ), if they are not obscured by pathology
Fair	The image is less well focused (than good), with it becoming more difficult to determine the ends of the larger vessels approaching the FAZ
	Retinal details are slightly fuzzy but subtle lesions, such as small retinal haemorrhages, can still be seen and graded
Poor gradeable	The image is less well focussed (than fair), but it is possible to glean some information for grading
	Clarity is decreased so that subtle lesions might be missed, but is sufficient for assessment of large retinal haemorrhages and large retinal vessels
Poor ungradeable	This should be selected if the grader is unable to evaluate or distinguish (with more than 50 % confidence) the absence or presence of any feature in all of the available images