June 2021
Volume 62, Issue 8
Open Access
ARVO Annual Meeting Abstract  |   June 2021
A-type Horizontal Cell-Coupling is Enhanced in Myopic Guinea Pig Retina
Author Affiliations & Notes
  • William Myles
    Vision Sciences, The University of Newcastle Hunter Medical Research Institute, New Lambton, New South Wales, Australia
  • Sally A McFadden
    Vision Sciences, The University of Newcastle Hunter Medical Research Institute, New Lambton, New South Wales, Australia
  • Footnotes
    Commercial Relationships   William Myles, None; Sally McFadden, ALCON (C), Dopavision (C), Myopia treament (P)
  • Footnotes
    Support  Funding: HMRI G 140 0967
Investigative Ophthalmology & Visual Science June 2021, Vol.62, 2279. doi:
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    • Get Citation

      William Myles, Sally A McFadden; A-type Horizontal Cell-Coupling is Enhanced in Myopic Guinea Pig Retina. Invest. Ophthalmol. Vis. Sci. 2021;62(8):2279.

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

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Purpose : Myopia (short-sightedness) is caused by excessive ocular growth. Hyperopic defocus can experimentally induce myopia, however the underlying mechanisms are not fully understood. Dopamine, retinoic acid and nitric oxide are intrinsic to eye growth and each helps regulate retinal gap-junction conductance. As such, cell-cell coupling may play an important role in the propagation of ocular growth signals in the retina. We investigated whether coupling between A-type horizontal cells (HC) is altered in myopic guinea pig retina.

Methods : Myopia was induced in guinea pigs from p6 using -6 diopter lenses covering one eye for 14 days. Coupling was assessed using cut-loading. Briefly; whole retinas were sustained in Ames solution (37oC, bubbled with 95% O2 5% CO2) and a cut made with a scalpel blade coated in neurobiotin (3% wt/v in Ames media). Retinas were incubated for 25 minutes to allow dye to transfer, fixed (4% PFA 30 minutes), reacted with streptavidin (1:100 in PBS) and imaged using a confocal microscopy. Dye-transfer through HCs was modelled by measuring the decline in cell fluorescence per distance from the cut. For lighting experiments, animals were either dark or light-adapted for one hour prior to euthanasia and retinas were sustained in these lighting conditions for all subsequent stages.

Results : Lens-wearing Guinea pigs developed -4.95D of relative myopia in the lens-wearing eye compared with the contralateral control (W=-2.521, p=0.012). Across both eyes, A-type HCs were more extensively coupled in the superior retina than the inferior (F=7.684, p=0.024). The lens-wearing eye displayed significantly increased A-type HC coupling within both the superior and inferior retina under dark-adapted conditions relative to the contralateral control (F=6.556, p=0.034).
A-type HC coupling was dependant on the lighting environment, with light-adapted retinas displaying reduced coupling compared to dark-adapted retinas (F=17.587, p=0.001).

Conclusions : A-type HC-coupling is locally higher in superior retina which is naturally more myopic. Myopia development enhances coupling further and is possibly involved in propagating ocular growth signals in response to ocular defocus. Since coupling in A-type HCs is also enhanced by dark adaption, and conversely reduced by the light, it is possible that light stimulation may be used to counteract myopia development.

This is a 2021 ARVO Annual Meeting abstract.


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