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 judged	Acceptance for grading
(a) Definition of image
(i) Good; all features fully assessable	Accepted
(ii) Moderate; some haziness of some small vessels	Accepted
(iii) Poor; unable to define small vessels	Rejected
(b) Field of image seen
(i) Full image seen	Accepted
(ii) >3/4 of image seen	Accepted
(iii) <3/4, but >1/2 of image seen	Rejected
(iv) <1/2 of image seen	Rejected
(c) Fovea visible
(i) Yes	Accepted
(ii) No	Rejected