Abstract
Introduction: :
Purposes:-To correlate MOFO mfERG with clinical functional and morphological tests-To evaluate the functional changes of various types of diabetic retinopathy (DR) lesions by MOFO mfERG
Methods: :
38 diabetic patients were examined: 9 of them (aged 49.7± 6.4years) were free from DR while 29 of them (aged 49.8 ± 6.4years) had non-proliferative DR. 14 normal subjects (aged 49.4 ± 7.0years) were also recruited. Each subject underwent the Humphrey visual field (VF) test. The retinal nerve fiber layer thickness (RNFL) was measured by the optical coherence tomography (OCT). One eye of each subject was selected for the 103-hexagonal MOFO mfERG assessment under 98% and 46% contrast conditions. 103 hexagons were grouped into 35 regions. Regional z-scores of mfERG responses (direct component DC and induced component IC) were calculated to study the functional changes among various types of DR. Correlations among the tests were studied.
Results: :
Individual mean z-score of the DC and IC amplitude had a moderate correlation with VF mean defect (r=0.33 to 0.47, p<0.025). No correlation existed between mfERG and the RNFL thickness (r=0 to 0.25, p>0.07). 1019 regional MOFO responses were divided into 5 groups: a) control (47.7%), b) no non-proliferative DR (29.6%), c) hard exudates (2.8%), d) dot/blot-hemorrhages (16.5%) and e) flame-hemorrhages with soft exudates (3.4%). Under both contrasts, z-score of the DC and IC amplitude was significantly smaller in the diabetic group (p<0.01). The z-score of IC amplitude in the cases with retinopathy was further reduced than those without retinopathy (p<0.05).
Conclusions: :
MOFO mfERG correlates well with the clinical functional test but not with the morphological test. Reduction of the DC (mainly from the outer retina) and IC (mainly from the inner retina) responses indicates that the adaptive function may deteriorate before vascular and structural changes in diabetes. MOFO mfERG may provide a way for the early functional detection of the diabetic retina.Keywords: multifocal electroretinogram, diabetic retinopathy, adaptation
Keywords: electrophysiology: clinical • diabetic retinopathy • perimetry