July 2018
Volume 59, Issue 9
Open Access
ARVO Annual Meeting Abstract  |   July 2018
Shape discrimination hyperacuity robust to decreased retinal illuminance and induced optical degradation for achromatic and colour vision
Author Affiliations & Notes
  • Luis Garcia-Suarez
    School of Health Professions, Plymouth University, Plymouth, Devon, United Kingdom
  • Mona SP Mousavi-Jalali
    School of Health Professions, Plymouth University, Plymouth, Devon, United Kingdom
  • Melissa Nelson
    School of Health Professions, Plymouth University, Plymouth, Devon, United Kingdom
  • Footnotes
    Commercial Relationships   Luis Garcia-Suarez, None; Mona Mousavi-Jalali, None; Melissa Nelson, None
  • Footnotes
    Support  none
Investigative Ophthalmology & Visual Science July 2018, Vol.59, 5964. doi:
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      Luis Garcia-Suarez, Mona SP Mousavi-Jalali, Melissa Nelson; Shape discrimination hyperacuity robust to decreased retinal illuminance and induced optical degradation for achromatic and colour vision. Invest. Ophthalmol. Vis. Sci. 2018;59(9):5964.

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

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Abstract

Purpose : Reduced pupil size and lens opacities are typically age related and can often occur concurrently with retinal disease such as age-related macular degeneration (AMD). Hyperacuity tests are known to be resistant to the optical degradation and previous studies have suggested shape discrimination hyperacuity (SDH) to be a good test to monitor the progression of retinal changes in AMD. This study aims to determine the effects of decreased retinal illuminance and induced optical degradation on a SDH task and whether the effects are similar for achromatic, red-green and yellow-blue stimuli.

Methods : Three healthy subjects observed monocularly the radial frequency (RF) test displayed on a calibrated CRT monitor. RF stimuli consisted of a circular pattern (4th derivative of a Gaussian) with a 8° radius, a peak spatial frequency of 1cpd and a RF of 6. Using a two-interval forced-choice staircase, modulation thresholds for the deformations of the RF pattern were measured under decreased retinal illuminance using neutral density filters (ND 0.6, 1.2 and 1.8 log) and increased light scatter using Bangerter foils (BF 0.8, 0.6 and 0.4). All conditions were randomized. Stimuli were designed to isolate the achromatic (ACH), red-green (RG) and yellow-blue (YB) post-receptoral systems. Isoluminant points and a contrast matching task for setting the different colour stimuli to equivalent contrasts were completed beforehand for each subject.

Results : For all three observers, performance in SDH was best for the ACH condition followed by the YB and was worse for the RG condition. Modulation thresholds for YB and RG stimuli were respectively on average 2.4x and 3.6x higher than ACH thresholds. SDH performance was minimally affected by the introduction of the different ND and BF filters. For each colour condition, thresholds were similarly on average 1.2x higher with filters than with no filters. ANOVA tests confirmed that there were no significant differences in performance between filter levels.

Conclusions : The present results show that SDH are resistant to decreased retinal illuminance and increased light scatter. They suggest that colour vision performs worse but may share similar mechanisms in SDH to the ACH system. These results confirm that RF stimuli, including RG and YB patterns, are a very attractive type of stimulus to study visual function in retinal diseases.

This is an abstract that was submitted for the 2018 ARVO Annual Meeting, held in Honolulu, Hawaii, April 29 - May 3, 2018.

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