The effects of severe myopia on the properties of sampling units in peripheral retina

Research output: Contribution to journalArticle

Abstract

Significance: Poor peripheral visual acuity in myopia may reflect, in part, photoreceptor misalignment with the exit pupil of the eye. We speculate that if such misalignment causes sufficient visual deprivation and/or disrupts retinal feedback processes, it may influence eye growth itself.
Purpose: It is known that myopic eyes have a reduced peripheral resolution acuity relative to emmetropic eyes, though it remains unclear how mechanical stretching of the retina in myopia impacts on peripheral visual performance. Our aim was to determine how retinal stretching affects the properties of sampling units in peripheral vision.
Methods: Three-dimensional magnetic resonance imaging provided a depiction in vivo of ocular shape, allowing the inter-eye ratio of retinal image surface areas and the relative alignment of surfaces to be determined in our observer, who was unique in having severe myopia in the right eye (~21D) but only modest myopia in the left (~3D). Visual performance was assessed for the
detection and direction discrimination of drifting sinusoids positioned 40º in the temporal retina. Applying the sampling theorem to our measures, we estimated the density and cut-off frequency of the underlying sampling units.
Results: The retinal image surface area of the right eye was 40% larger than that of the left, and was rotated 8.9º anticlockwise relative to the left eye’s image surface. In agreement with a linear stretch model of myopia, the sampling density of the right eye was reduced by approximately the same ratio as that predicted from the inter-eye MRI data, namely 1.18. However, the cut-off
frequency (cycles/mm) of the right eye was approximately half that of the left, a reduction that cannot be explained solely by a linear areal expansion of retinal sampling units.
Conclusions: Poor peripheral acuity in severe myopia may be caused, at least in part, by receptoral misalignment with the exit pupil.
Original languageEnglish
Pages (from-to)99–404
JournalOptometry and Vision Science
Volume95
Issue number4
Early online date16 Mar 2018
DOIs
Publication statusPublished - 1 Apr 2018

Bibliographical note

This is not the final version of record. This is the accepted manuscript of the article: Nagra, Manbir; Gilmartin, Bernard; Logan, Nicola, S.; Anderson, Stephen, J. The Effects of Severe Myopia on the Properties of Sampling Units in Peripheral Retina. Optometry and Vision Science: March 16, 2018. https://dx.doi.org/10.1097/OPX.0000000000001199

Funding: College of Optometrist and the Lord Dowding Fund for Humane Research

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