title: Multifocal electroretinogram responses in Nepalese diabetic patients without retinopathy.
abstract: OBJECTIVE
  To determine neuroretinal function with multifocal electroretinogram (mfERG) in diabetic subjects without retinopathy.
  
  
  METHODS
  Multifocal electroretinogram (mfERG) was performed in 18 eyes of 18 diabetic subjects without retinopathy and 17 eyes of 17 age and gender-matched healthy control participants. Among 18 diabetic subjects, two had type 1 and 16 had type 2 diabetes. MfERG responses were averaged by the retinal areas of six concentric rings and four quadrants, and 103 retinal locations; N1-P1 amplitude and P1-implicit time were analysed.
  
  
  RESULTS
  Average mfERG N1-P1 amplitude (in nv/deg(2)) of 103 retinal locations was 56.3 ± 17.2 (mean ± SD) in type 1 diabetic subjects, 47.2 ± 9.3 in type 2 diabetic subjects and 71.5 ± 12.7 in controls. Average P1-implicit time (in ms) was 43.0 ± 1.3 in type 1 diabetic subjects, 43.9 ± 2.3 in type 2 diabetic subjects and 41.9 ± 2.1 in controls. There was significant reduction in average N1-P1 amplitude and delay in P1-implicit time in type 2 diabetic subjects in comparison to controls. mfERG amplitude did not show any significant correlation with diabetes duration and blood sugar level. However, implicit time showed a positive correlation with diabetes duration in type 2 diabetic subjects with diabetes duration ≥5 years.
  
  
  CONCLUSIONS
  This is the first study in a Nepalese population with diabetes using multifocal electroretinography. We present novel findings that mfERG N1-P1 amplitude is markedly reduced along with delay in P1-implicit time in type 2 diabetic subjects without retinopathy. These findings indicate that there might be significant dysfunction of inner retina before the development of diabetic retinopathy in the study population, which have higher prevalence of diabetes than the global estimate and uncontrolled blood sugar level.
authors.affiliation: Visual Science and Medical Retina Laboratories, Institute of Health and Biomedical Innovation, School of Optometry and Vision Science, Queensland University of Technology, 60 Musk Avenue, Kelvin Grove, Brisbane, QLD, 4059, Australia, p.adhikari@qut.edu.au.
authors.forename: Prakash
authors.initials: P
authors.lastname: Adhikari
authors.forename: Subash
authors.initials: S
authors.lastname: Marasini
authors.forename: Raman Prasad
authors.initials: RP
authors.lastname: Sah
authors.forename: Raman Prasad
authors.initials: RP
authors.lastname: Shah
authors.forename: Sagun Narayan
authors.initials: SN
authors.lastname: Joshi
authors.forename: Jeevan Kumar
authors.initials: JK
authors.lastname: Shrestha
mesh_terms: D001786:Blood Glucose / Q000378:metabolism; D003922:Diabetes Mellitus, Type 1 / Q000208:ethnology / Q000503:physiopathology*; D003924:Diabetes Mellitus, Type 2 / Q000208:ethnology / Q000503:physiopathology*; D003930:Diabetic Retinopathy / Q000208:ethnology / Q000503:physiopathology*; D004596:Electroretinography; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009390:Nepal; D012160:Retina / Q000503:physiopathology*; D014792:Visual Acuity
chemical_list: D001786:Blood Glucose