June 2015
Volume 56, Issue 7
Free
ARVO Annual Meeting Abstract  |   June 2015
Abnormal rod- and cone-isolated flicker electroretinograms in carriers of X-linked retinoschisis
Author Affiliations & Notes
  • J Jason McAnany
    Ophthalmology and Visual Sciences, University of Illinois at Chicago, Chicago, IL
  • Jason C Park
    Ophthalmology and Visual Sciences, University of Illinois at Chicago, Chicago, IL
  • Frederick T Collison
    The Pangere Center for Hereditary Retinal Diseases, The Chicago Lighthouse for People Who Are Blind or Visually Impaired, Chicago, IL
  • Gerald A Fishman
    Ophthalmology and Visual Sciences, University of Illinois at Chicago, Chicago, IL
    The Pangere Center for Hereditary Retinal Diseases, The Chicago Lighthouse for People Who Are Blind or Visually Impaired, Chicago, IL
  • Footnotes
    Commercial Relationships J Jason McAnany, None; Jason Park, None; Frederick Collison, None; Gerald Fishman, None
  • Footnotes
    Support None
Investigative Ophthalmology & Visual Science June 2015, Vol.56, 478. doi:https://doi.org/
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    • Get Citation

      J Jason McAnany, Jason C Park, Frederick T Collison, Gerald A Fishman; Abnormal rod- and cone-isolated flicker electroretinograms in carriers of X-linked retinoschisis. Invest. Ophthalmol. Vis. Sci. 2015;56(7 ):478. doi: https://doi.org/.

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      © ARVO (1962-2015); The Authors (2016-present)

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Abstract

Purpose: Identifying potential carriers of X-linked retinoschisis (XLRS) in some cases requires identifying mutations in the RS1 gene, as XLRS carriers generally do not exhibit clinically-apparent fundus abnormalities. This study evaluated rod- and cone-isolated electroretinograms (ERGs) as a possible means to identify such potential carriers.

Methods: Full-field ERGs were recorded from the right eye of 7 obligate carriers of XLRS (mean age, 63.7 years) and 10 normally-sighted subjects (mean age, 33.1 years) under two paradigms: 1) The standard ISCEV paradigm, consisting of scotopic single-flash, photopic single-flash, and 30-Hz flicker responses; 2) Rod-isolated (ERGR), cone-isolated (ERGC), and non-receptor-specific (ERGR+C) flicker responses. ERGs were obtained using a 4-primary LED-based ganzfeld photostimulator and standard ERG recording techniques. The 4 primaries were modulated sinusoidally in phase to achieve non-receptor-specific activation (ERGR+C) or in counter-phase to achieve ERGR and ERGC by means of triple silent substitution. After 30 minutes of dark adaptation, 8 and 15 Hz ERGR, ERGC, and ERGR+C responses were obtained at a mean luminance level of 24 cd/m2. Receiver operating characteristic (ROC) analysis was performed on the amplitude and phase of the fundamental response component derived by Fourier analysis.

Results: All ISCEV and 15-Hz flicker ERG responses were within the normal range for all carriers. The 8-Hz ERGR, ERGC, and ERGR+C amplitudes were also generally within the normal range. In contrast, the carriers had clear ERGR, ERGC, and ERGR+C timing abnormalities. That is, phase was advanced beyond the range of normal for the ERGR (3 carriers), ERGC (5 carriers), and ERGR+C (4 carriers). Only one carrier had normal responses under all conditions. Using 8-Hz response phase as the sole metric to distinguish carriers from controls, ROC analysis found the area under the curve to be 90% (p = 0.006), 86% (p = 0.01), and 69% (p = 0.20), for the ERGC, ERGR+C, and ERGR, respectively.

Conclusions: In 6 of 7 carriers of XLRS, abnormal flicker ERG timing was observed that was restricted to 8-Hz, which is the stimulus frequency at which abnormal rod-cone interactions were reported in a previous psychophysical study of XLRS carriers. The 8-Hz flicker ERG, particularly under conditions in which cone-pathway response is isolated, may be a useful marker for the carrier state of XLRS.

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