title: Global flash multifocal electroretinogram: early detection of local functional changes and its correlations with optical coherence tomography and visual field tests in diabetic eyes.
abstract: OBJECTIVE
  To investigate the correlations of the global flash multifocal electroretinogram (MOFO mfERG) with common clinical visual assessments--Humphrey perimetry and Stratus circumpapillary retinal nerve fiber layer (RNFL) thickness measurement in type II diabetic patients.
  
  
  METHODS
  Forty-two diabetic patients participated in the study: Ten were free from diabetic retinopathy (DR), while the remainder suffered from mild to moderate nonproliferative diabetic retinopathy. Fourteen age-matched controls were recruited for comparison. MOFO mfERG measurements were made under high- and low-contrast conditions. Humphrey central 30-2 perimetry and Stratus OCT circumpapillary RNFL thickness measurements were also performed. Correlations between local values of implicit time and amplitude of the mfERG components [direct component (DC) and induced component (IC)], and perimetric sensitivity and RNFL thickness were evaluated by mapping the localized responses for the three subject groups.
  
  
  RESULTS
  MOFO mfERG was superior to perimetry and RNFL assessments in showing differences between the diabetic groups (with and without DR) and the controls. All the MOFO mfERG amplitudes (except IC amplitude at high contrast) correlated better with perimetry findings (Pearson's r ranged from 0.23 to 0.36, p < 0.01) than did the mfERG implicit time at both high and low contrasts across all subject groups. No consistent correlation was found between the mfERG and RNFL assessments for any group or contrast conditions. The responses of the local MOFO mfERG correlated with local perimetric sensitivity but not with RNFL thickness.
  
  
  CONCLUSIONS
  Early functional changes in the diabetic retina seem to occur before morphological changes in the RNFL.
authors: Laboratory of Experimental Optometry Neuroscience, School of Optometry, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong SAR, China.
authors: J C Y
authors: JC
authors: Lung
authors: P G
authors: PG
authors: Swann
authors: D S H
authors: DS
authors: Wong
authors: H H L
authors: HH
authors: Chan
mesh_terms: D003930:Diabetic Retinopathy / Q000175:diagnosis* / Q000503:physiopathology; D042241:Early Diagnosis; D004596:Electroretinography / Q000379:methods*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D012165:Retinal Ganglion Cells / Q000502:physiology*; D041623:Tomography, Optical Coherence / Q000379:methods*; D058609:Visual Field Tests; D014794:Visual Fields