title: Multifocal electroretinogram in non-pathological myopic subjects: correlation with optical coherence tomography.
abstract: OBJECTIVE
  To investigate the changes of retinal function in non-pathological myopic subjects using multifocal electroretinography (mfERG) and to correlate the data with the central macular thickness obtained using optical coherence tomography (OCT).
  
  
  METHODS
  One hundred and thirteen subjects (113 eyes) with age range from 18 to 35y were enrolled in the study. The subjects were divided into four groups according to spherical equivalent (SE) and axial length (AL): emmetropia group (EG, n=31; SE: +0.75 to -0.50 D; AL: 22 to 24 mm), low and medium myopia group (LMMG, n=26; SE: >-0.50 to -6.00 D; AL: >24 to 26 mm), high myopia group (HMG, n=34; SE: >-6.00 to -10.00 D; AL: >26 to 28 mm) and super high myopia group (SHMG, n=22; SE: >-10.00 D; AL:>28 mm). The P1 amplitude density, P1 amplitude, and P1 implicit time of the first-order kernel mfERG responses were obtained and grouped into five rings. The central subfield macular thickness (CST) was obtained using macular cube 512×218 scan of Cirrus HD-OCT.
  
  
  RESULTS
  With the increasing of eccentricity, the first positive peak (P1) amplitude density (P=0.0000, 0.0001, 0.0021 in ring 1-3 respectively) and P1 amplitude (all P=0.0000 in ring 1-5) of each group decreased. With the increasing of myopia, P1 implicit time gradually extended (all P=0.0000 in ring 1-3). The average CST in four diagnostic groups was 241.56±12.72 µm, 244.56±12.19 µm, 254.33±11.61 µm, 261.75±11.83 µm respectively. With the increasing of myopia, CST increased (P<0.001). There was negative relationship between CST and P1 amplitude, P1 amplitude density (r=-0.402, P<0.001; r=-0.261, P=0.003). There was positive relationship between CST and P1 implicit time (r=0.34, P<0.001).
  
  
  CONCLUSIONS
  With the increasing of myopia, P1 amplitude density and P1 amplitude of the first-order reaction gradually reduced. This showed potential decline in retinal function in myopia. To some extent it may reflect the functional disorder or depression of the visual cells. The exact mechanism needs further study.
authors.affiliation: Department of Ophthalmology, Second People's Hospital, Jinan 250001, Shandong Province, China.
authors.forename: Ai-Ping
authors.initials: AP
authors.lastname: Song
authors.affiliation: Department of Ophthalmology, Second People's Hospital, Jinan 250001, Shandong Province, China.
authors.forename: Tao
authors.initials: T
authors.lastname: Yu
authors.affiliation: Department of Ophthalmology, Second People's Hospital, Jinan 250001, Shandong Province, China.
authors.forename: Jian-Rong
authors.initials: JR
authors.lastname: Wang
authors.affiliation: Department of Ophthalmology, Second People's Hospital, Jinan 250001, Shandong Province, China.
authors.forename: Wei
authors.initials: W
authors.lastname: Liu
authors.affiliation: Department of Ophthalmology, Second People's Hospital, Jinan 250001, Shandong Province, China.
authors.forename: Yan
authors.initials: Y
authors.lastname: Sun
authors.affiliation: Department of Ophthalmology, Second People's Hospital, Jinan 250001, Shandong Province, China.
authors.forename: Su-Xiang
authors.initials: SX
authors.lastname: Ma
keywords: multifocal electroretinogram; myopia; optical coherence tomography