Clinical:Scottish Diabetic Retinopathy Grading Scheme v 2007

The Scottish national screening program for diabetic retinopathy was established on the basis of the recommendations made by the Health Technology Board for Scotland (HTBS). HTBS after evaluationg the available literature recommended that the screening program should be based on digital fundus photography.^[1]

The screening program managed at a national level by executive group of the DIABETIC RETINOPATHY SCREENING COLLABORATIVE of the National Services Division,Scotland ^[2]. All patients have a single 45 degree disc/macula photograph taken. A mydriatic or pupil dilating drop is instilled in the eye only if a good quality photograph is not without mydriasis (Staged Mydriasis). Since most image grading schemes are based on at least 2 fields per eye a separate grading scheme was developed and is listed below Scottish Diabetic Retinopathy Grading Scheme 2007 v1.1

The scheme is based on identification of individual features and is hierarchical. Since macular odema cannot be diagnosed by routine fundus photography, the word Maculopathy was coined to identify such patients by the presence of surrogate markers of retinopathy like exudates and blot hemorrhages. This is graded separately and in addition to the overall retinopathy grade.

R0 (no visible retinopathy) Description: No diabetic retinopathy anywhere Outcome: Rescreen 12 months

R1 (mild) Description: Background diabetic retinopathy BDR - mild The presence of any of the following features anywhere in the picture dot haemorrhages, microaneurysms,hard exudates,cotton wool spots,blot haemorrhages, superficial/ flame shaped haemorrhages. These patient are invited for re-screening in 12 months

R2(observable background) Description: Background diabetic retinopathy BDR - observable The presence of four or more blot haemorrhages (Airlie house (AH) standard photograph 2a) in one hemi-field only (Inferiorand superior hemi-fields delineated by a line passing through the centre of the fovea and optic disc). These patient are invited for re-screening in 6 months or refered to ophthalmology if this is not feasible

R3 (referable background) Description: Background diabetic retinopathy BDR – referable The presence of Four or more blot haemorrhages (AH standard photograph 2a) in both inferior and superior hemi-fields, Venous beading (AH standard photograph 6a), IRMA (AH standard photograph 8a) These patient are referred to ophthalmology These patients may be kept under surveillance and will not necessarily receive immediate laser treatment.

R4 (proliferative) Description: Proliferative diabetic retinopathy PDR The presence of active new vessels, vitreous haemorrhage. These patient are referred to ophthalmology These patients are likely to receive laser treatment or another intervention.

R6 (inadequate) In these patients the retinal images are not sufficiently visible for assessment. These screening episodes are also called Technical failure. An alternative screening examination using slit lamp biomicroscopy or repeat photography is planned. ^[3]