Defining Diabetic Retinopathy Severity

The fundus abnormalities seen in diabetic retinopathy can conceptually be split into three categories – those findings resulting from leaking microvasculature (hemorrhages, lipid exudates, retinal edema); those findings resulting from structural damage to the microvasculature wall (microaneurysms); and those findings resulting from ischemia with a subsequent overproduction of vascular growth factors (cottonwool patches, intraretinal microvascular abnormalities [IRMA], preretinal neovascularization, fibrous proliferation, and vitreous hemorrhage). The severity of each of these findings can be classified and quantified based on the degree of retina involvement, e.g., the number of microaneurysms and hemorrhages in each quadrant or photographic field, the area of retina affected by neovascular tissue or IRMA, the area of macula involved with retinal thickening. Classification schemes are a means to categorize the varying degrees of such findings to facilitate communication.As with all specialized languages, the value of these languages depends upon who is speaking to whom. The ultimate goal of classification schemes is to provide a system to improve patient care. This may be achieved initially by precise communication among researchers to define categories by which the natural history and subsequent response to intervention(s) can be identified. Once these research goals have been achieved these classification schemes should be understandable and reproducible by practicing clinicians. If not, then modification of these classification schemes is desirable to allow clinicians to communicate among themselves and with their patients the expected results of therapies demonstrated to be beneficial in clinical trials. One should realize that the goals of communication between researchers may be different from the goals of communication between clinicians and may likewise be different from the goals of communication between clinician and patient. Evolution of classification schemes is desirable dependent upon who is communicating with whom.