Abstract
Purpose: :
The count and distribution of microaneurysms(MAs) is a predictor of severity of vascular changes in diabetic retinopathy while the visual functions are thought to correlate better with neuronal changes. This study aims to quantify the impact of MA count and distribution on visual function and neuronal changes in DR.
Methods: :
Thirty-nine eyes of 23 patients with type 2 diabetes and mild non-proliferative DR were recruited for this study. Patients underwent colour fundus photography, Cirrus OCT scanning and HbA1c measurement. Using Retmarker, MA counts of the inner, middle and outer circles, as defined by ETDRS, were done. Functional tests performed include best corrected visual acuity (ETDRS letters), fixation and retinal sensitivity using microperimetry (MP-1), contrast sensitivity (Pelli-Robson tests) and colour contrast (ChromaTest). Results from the functional tests were correlated with OCT-computed qualitative and quantitative measurements, MA counts and HbA1c. Pearson’s correlation test was used and P<0.05 was considered statistically significant.
Results: :
The number or location of MAs did not correlate with average macular thickness or the individual retinal thickness in each of the nine grids. Neither the average macular thickness nor retinal thickness within each individual grid correlated with any of the tests of visual functions including visual acuity, contrast sensitivity and retinal sensitivity using MP-1. MA count and location also did not correlate to any of the tests of visual functions.
Conclusions: :
Microaneurysm count and distribution are an independent risk factor for DR and do not correlate with visual functions and neuronal changes.
Keywords: diabetic retinopathy