title: A late foveal response component of multifocal electroretinograms in healthy subjects.
abstract: OBJECTIVE
  To investigate the characteristics of the late foveal response component (lfrc) that presents on the first slice of the second-order kernel (K2.1) in multifocal electroretinograms (mfERGs).
  
  
  METHODS
  mfERGs with 37 hexagonal stimulus elements were obtained from 27 healthy subjects under a stimulus intensity of 2.67 cds/m2, base rate of 75 Hz, and a net recording time of 1 min 49.2 s, using bipolar contact lens electrodes. The responses on the centermost hexagon (with a diameter of 4.5°-5.2°) were designated as foveal mfERGs.
  
  
  RESULTS
  The foveal mfERG of the first-order kernel (K1) was shaped similarly to the K1 of the surrounding mfERGs. The foveal mfERG of K2.1 differed from the K2.1s of the surrounding mfERGs. This difference varied among subjects; however, the potential (0.34 ± 0.10 µV: mean ± SD) of the lfrc acutely changed at approximately 50 ms (range 48.56 ± 1.02-56.86 ± 1.99 ms). Whereas the amplitudes of the other major components of K1 and K2.1 significantly decreased with increasing refractive error, the amplitude of lfrc was not significantly correlated with refraction in this cohort.
  
  
  CONCLUSIONS
  The lfrc was obtained only on the centermost hexagon within an appropriate recording time (<2 min). This finding reflects the particular structure and peculiar adaptiveness of the fovea, a specialized area of the human retina, and enables the estimation of foveal function in clinical practice.
authors.affiliation: Department of Ophthalmology, Sohag University, Sohag, Egypt.|Department of Ophthalmology, Fujita Health University Banbuntane Hotokukai Hospital, Otobashi 3-6-10, Nakagawa-Ku, Nagoya, Aichi, 454-8509, Japan.
authors.forename: Gamal Tamam Ahmed
authors.initials: GT
authors.lastname: Kariman
authors.affiliation: Department of Ophthalmology, Fujita Health University Banbuntane Hotokukai Hospital, Otobashi 3-6-10, Nakagawa-Ku, Nagoya, Aichi, 454-8509, Japan. ysmd@fujita-hu.ac.jp.|Department of Ophthalmology, Fujita Health University, Toyoake, Aichi, Japan. ysmd@fujita-hu.ac.jp.
authors.forename: Yoshiaki
authors.identifier: http://orcid.org/0000-0001-5277-7768
authors.initials: Y
authors.lastname: Shimada
authors.affiliation: Department of Ophthalmology, Fujita Health University, Toyoake, Aichi, Japan.
authors.forename: Masayuki
authors.initials: M
authors.lastname: Horiguchi
mesh_terms: D000328:Adult; D004596:Electroretinography / Q000379:methods*; D005584:Fovea Centralis / Q000502:physiology*; D006801:Humans; D008297:Male; D008839:Microelectrodes; D008875:Middle Aged; D012160:Retina / Q000503:physiopathology
keywords: Electroretinogram; Fovea; Late foveal response component (lfrc); Multifocal electroretinogram; Nonlinear response