June 2022
Volume 63, Issue 7
Open Access
ARVO Annual Meeting Abstract  |   June 2022
Photopic Negative Response as an Objective Outcome Measure in Dominant Optic Atrophy
Author Affiliations & Notes
  • Qingqing (Kinna) Zhao
    Ottawa Hospital Research Institute, Ottawa, Ontario, Canada
    University of Ottawa Eye Institute, Ottawa, Ontario, Canada
  • Hong-An Nguyen
    Ottawa Hospital Research Institute, Ottawa, Ontario, Canada
    University of Ottawa Eye Institute, Ottawa, Ontario, Canada
  • Melanie Renee Lalonde
    Ottawa Hospital Research Institute, Ottawa, Ontario, Canada
    University of Ottawa Eye Institute, Ottawa, Ontario, Canada
  • Stuart Glenn Coupland
    Ottawa Hospital Research Institute, Ottawa, Ontario, Canada
    University of Ottawa Eye Institute, Ottawa, Ontario, Canada
  • Rustum Karanjia
    University of Ottawa Eye Institute, Ottawa, Ontario, Canada
    Doheny Eye Institute, Los Angeles, California, United States
  • Footnotes
    Commercial Relationships   Qingqing (Kinna) Zhao None; Hong-An Nguyen None; Melanie Lalonde None; Stuart Coupland Diagnosys LLC (C), Code C (Consultant/Contractor); Rustum Karanjia None
  • Footnotes
    Support  United Mitochondrial Disease Foundation (UMDF) and International Foundation for Optic Nerve Disease (IFOND)
Investigative Ophthalmology & Visual Science June 2022, Vol.63, 746 – F0398. doi:
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      Qingqing (Kinna) Zhao, Hong-An Nguyen, Melanie Renee Lalonde, Stuart Glenn Coupland, Rustum Karanjia; Photopic Negative Response as an Objective Outcome Measure in Dominant Optic Atrophy. Invest. Ophthalmol. Vis. Sci. 2022;63(7):746 – F0398.

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

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Abstract

Purpose : Kjer’s dominant optic atrophy (DOA) is an autosomal dominant disorder caused by mutation in the OPA1 gene in chromosome 3. The mutation results in retinal ganglion cell (RGC) degeneration and optic atrophy. The affected patients have varying degrees of visual deficits, including decreased best corrected visual acuity (BCVA), visual field defects, cataracts, and nystagmus. These visual deficits pose challenges to clinical testing. Subjective assessments such as BCVA and visual field tests do not accurately reflect the disease severity due to floor effect. Similarly, the retinal nerve fiber layer (RNFL) thickness, which reflects the structural changes of the retina, also plateaus as the disease progresses.

Photopic negative response (PhNR), recorded via the electroretinogram, can be used to assess the RGC dysfunction in the absence of reliable patient fixation or clear ocular media. The purpose of this study was to validate the use of PhNR as an objective measurement to assess visual function in patients with DOA.

Methods : Data were collected at the University of Ottawa Eye Institute. Ganglion cell complex analysis was performed by Cirrus HD-OCT (Carl Zeiss Meditec). Mean deviations were analyzed by Humphrey Field Analyzer 3 (Carl Zeiss Meditec). PhNR data of control subjects and DOA patients were recorded on Espion E3 (v.6, Diagnosys LLC). Briefly, full field PhNRs were recorded using red (640 nm) flashes on blue (470 nm) rod saturating background. PhNR was performed using three stimulus intensities: 1, 5, and 7 cd●s/m2. Statistical analysis was performed using SigmaPlot (v.14.5).

Results : Clinical data from 14 eyes of 7 DOA patients with BCVA varying between 20/40 to counting fingers at 2 ft, were compared to control data (n=28). All DOA patients showed visual field mean deviations outside of normal limits, and abnormally reduced RGC layer, inner plexiform layer, and RNFL thickness. PhNR data demonstrated reduced amplitudes across all three stimulus intensities compared to controls (-8.8 ± 6.2 μV vs -32.6 ± 2.2 μV @ 1 cd●s/m2; -5.1 ± 4.6 μV vs -34.2 ± 2.5 μV @ 5 cd●s/m2; and -7.5 ± 4.7 μV vs -40.2 ± 3.4 μV @ 7 cd●s/m2; p = < 0.001).

Conclusions : In combination with the other standard clinical measurements, such as BCVA, visual field and RNFL thickness, the PhNR tests can provide objective measurement of the RGC layer integrity and serve as a biomarker for disease and therapy management.

This abstract was presented at the 2022 ARVO Annual Meeting, held in Denver, CO, May 1-4, 2022, and virtually.

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