Diabetic Retinopathy Grading

diab 01 Screenshot from 2015-03-06 20:50:40
diab 02 Screenshot from 2015-03-06 20:54:09
diab 03 Screenshot from 2015-03-06 20:54:41
Diabetic retinopathy is a progressive ophthalmic microvascular complication of diabetes characterised by the presence of microaneurysms, haemorrhages, exudates, venous changes, neovascularisation, and retinal thickening. It can involve the peripheral retina, the macula, or both.1 The various identifiable stages of the condition are described as: background where pathology is intraretinal, proliferative where pathology extends forward onto the retinal surface into the vitreous and beyond, and pre-proliferative where the condition exhibits signs of imminent proliferation.2
The Wisconsin Epidemiologic Study of Diabetic Retinopathy showed that background diabetic retinopathy (microaneurysms and haemorrhages) was present in nearly all subjects with type 1 diabetes of 20 years’ duration,3 and in 80% of those with type 2 diabetes of a similar duration.4 However, the grading scheme used was very complicated involving seven pictures of each eye making it impractical for a large-scale, population-based screening programme. The condition remains the leading cause of blindness among the UK’s working age population.5A comprehensive National Screening Programme is currently being implemented to meet targets set out in the National Service Framework for Diabetes.6 The National Screening Committee (NSC) has produced grading criteria (see Table 1) describing each level of disease determined by the lesions detected during screening, and management guidelines (see Table 2) to ensure appropriate monitoring and treatment of the condition.7 This is a simplified version of the Wisconsin grading criteria used in the Early Treatment Diabetic Retinopathy Study (ETDRS).Figures 1 to 6 show examples of retinal screening images grouped according to NSC grading criteria.

Table 1. National Screening Committee grading criteria — minimum data set7
  1. These are core data which can be expanded to meet local clinical and research needs.
Level R0 — None
Level R1 — Background
• Microaneurysm(s)
• Retinal haemorrhage(s) ± any exudate
Level R2 — Pre-proliferative
• Venous beading
• Venous loop or reduplication
• Intraretinal microvascular abnormality (IRMA)
• Multiple deep, round or blot haemorrhages
Cotton wool spots (CWS) — careful search for above features)
Level R3 — Proliferative
• New vessels on disc (NVD)
• New vessels elsewhere (NVE)
• Pre-retinal or vitreous haemorrhage
• Pre-retinal fibrosis ± tractional retinal detachment
Maculopathy (M0 — nil present, M1 — maculopathy)
• Exudate within 1 disc diameter (DD) of the centre of the fovea
• Circinate or group of exudates within the macula
• Retinal thickening within 1DD of the centre of the fovea (if stereo available)
• Any microaneurysm or haemorrhage within 1DD of the centre of the fovea only if associated with a best visual acuity of ≤ 6/12 (if no stereo)
Photocoagulation (P)
• Focal/grid to macula
• Peripheral scatter
Unclassifiable (U)
• Ungradable/unobtainable
Table 1. National Screening Committee management criteria/action7
R0 Annual screening
R1 Annual screening, inform diabetes care team
R2 Refer to hospital eye service
R3 Fast-track referral to hospital eye service
Maculopathy (M)
M0 Annual screening
M1 Refer to hospital eye service
Photocoagulation (P)
P1 New screenee — refer to hospital eye service
P2 Quiescent post treatment — annual screening
Other lesions (OL)
• Refer to hospital eye service or inform primary physician
Ungradable/unobtainable (U)
• Media opacity hospital eye service
Unscreenable

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