NON-RETINOVASCULAR LEAKAGE IN DIABETIC MACULOPATHY

Background-Diabetic macular oedema is the leading cause of vision dete rioration in diabetic retinopathy. Extracellular fluid within the reti na, which distorts the retinal architecture, was assumed to be strictl y of retinal vasculature origin. However, there is some experimental e vidence supporting clinical observations suggesting a possible role of the retinal pigment epithelium (RPE). An unusual form of diabetic mac ulopathy is presented in which the RPE and the subretinal space play t he main role. Methods-Fluorescein angiograms of 1850 non-proliferative diabetic retinopathy (NPDR) patients were examined. Nineteen eyes (14 patients, 1% of NPDR patients) met the criteria - mainly having minim al diabetic retinopathy with only a few microaneurysms and no clinical ly significant macular oedema (CSMO). Early phase angiograms were comp ared with late phase angiograms. Results-It was found that in all 19 e yes the area of diffuse RPE late phase leakage was spread around the m acular area. No cystic changes or cystoid macular oedema were present in any of the eyes and the visual acuity was 6/10 or better in all the eyes. Conclusions-Possible changes occur in the RPE that may be respo nsible for the late leakage in NPDR patients - namely, diabetic retina l pigment epitheliopathy. These changes are associated with a breakdow n of the outer blood-retinal barrier, consisting of leakage through RP E cells. No focal or diffuse leakage across the RPE has been reported in the literature related to the fluorescein angiograms in diffuse dia betic maculopathy.