title: Interocular symmetry of abnormal multifocal electroretinograms in adolescents with diabetes and no retinopathy.
abstract: OBJECTIVE
  To investigate, in adolescents with type 1 diabetes and no retinopathy, the spatial correspondence between abnormal multifocal electroretinogram (mfERG) responses in the two eyes.
  
  
  METHODS
  mfERG and fundus photographs were measured in both eyes of 68 adolescents with type 1 diabetes and no retinopathy (13 to 19 years old; best corrected visual acuity ≥ 20/20), and 30 age-matched controls. The mfERG stimulus was comprised of 103 hexagons, and subtended 45°. mfERG implicit times (IT) and amplitudes (AMP) were derived. Fifteen patients for IT, and five for AMP with at least one eye defined as abnormal (six or more locations with abnormal Z-scores; P < 0.03) were analyzed.
  
  
  RESULTS
  Nasal retina had significantly more abnormal IT locations compared with temporal retina (P = 0.015), and the opposite was true with regard to abnormal AMP (P < 0.001). The proportion of abnormal responses in the superior retina was not significantly different from that in the inferior retina (P > 0.1 for IT and AMP). Interocular correspondence of locations with abnormal mfERG IT was significant for all 15 patients (P values <0.0001-0.012), and agreement between eyes was 68% to 94% (AC1 agreement coefficient: 0.48-0.94). Overall interocular correspondence was also significant (P < 0.0002), with 86% agreement (AC1 = 0.76). Overall interocular correspondence of locations with abnormal mfERG AMP was also significant (P < 0.0002).
  
  
  CONCLUSIONS
  Interocular spatial correspondence of abnormal mfERG responses exists in adolescents with type 1 diabetes and no retinopathy. This is most apparent for IT abnormalities. This correspondence could be used in clinical trials, and raises the possibility of initiating treatment in both eyes at early disease stages as new topical treatments emerge.
authors.affiliation: School of Optometry, University of California, Berkeley, California 94720, USA. mlaron@berkeley.edu
authors.forename: Michal
authors.initials: M
authors.lastname: Laron
authors.forename: Marcus A
authors.initials: MA
authors.lastname: Bearse
authors.forename: Kevin
authors.initials: K
authors.lastname: Bronson-Castain
authors.forename: Soffia
authors.initials: S
authors.lastname: Jonasdottir
authors.forename: Barbara
authors.initials: B
authors.lastname: King-Hooper
authors.forename: Shirin
authors.initials: S
authors.lastname: Barez
authors.forename: Marilyn E
authors.initials: ME
authors.lastname: Schneck
authors.forename: Anthony J
authors.initials: AJ
authors.lastname: Adams
mesh_terms: D000293:Adolescent; D003922:Diabetes Mellitus, Type 1 / Q000503:physiopathology*; D003930:Diabetic Retinopathy / Q000503:physiopathology; D004596:Electroretinography; D005260:Female; D006442:Glycated Hemoglobin / Q000378:metabolism; D006801:Humans; D008297:Male; D012160:Retina / Q000503:physiopathology*; D014792:Visual Acuity / Q000502:physiology
chemical_list: D006442:Glycated Hemoglobin; C517652:hemoglobin A1c protein, human