Table 2

 Assessment of image quality and acceptability for grading. Photographs were deemed ungradable if any of the criteria below resulted in rejection, unless a specific reason for referral could be identified (for example, foveal changes seen even if only half the field could be visualised

Criteria judgedAcceptance for grading
(a) Definition of image
    (i) Good; all features fully assessableAccepted
    (ii) Moderate; some haziness of some small vesselsAccepted
    (iii) Poor; unable to define small vesselsRejected
(b) Field of image seen
    (i) Full image seenAccepted
    (ii) >3/4 of image seenAccepted
    (iii) <3/4, but >1/2 of image seenRejected
    (iv) <1/2 of image seenRejected
(c) Fovea visible
    (i) YesAccepted
    (ii) NoRejected