July 2019
Volume 60, Issue 9
Open Access
ARVO Annual Meeting Abstract  |   July 2019
Early changes in fundus reflectivity and retinal nerve fiber layer thickness in chickens during induction of deprivation myopia
Author Affiliations & Notes
  • Barbara Swiatczak
    University of Tuebingen, Germany
  • Marita P Feldkaemper
    University of Tuebingen, Germany
  • Frank Schaeffel
    University of Tuebingen, Germany
  • Footnotes
    Commercial Relationships   Barbara Swiatczak, None; Marita Feldkaemper, None; Frank Schaeffel, None
  • Footnotes
    Support  Marie Sklodowska-Curie Research training Network MyFun Grant MSCA-ITN-2015-675137
Investigative Ophthalmology & Visual Science July 2019, Vol.60, 4368. doi:
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      Barbara Swiatczak, Marita P Feldkaemper, Frank Schaeffel; Early changes in fundus reflectivity and retinal nerve fiber layer thickness in chickens during induction of deprivation myopia. Invest. Ophthalmol. Vis. Sci. 2019;60(9):4368.

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

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Purpose : Previous studies have shown that changes in functional activity in the retina can be visualized as changes in fundus reflectivity. In an attempt to identify changes that may occur during development of myopia, we have measured fundus reflectivity in chickens in vivo in visible (white) and near ultraviolet (UV) light (315-380 nm), using the chicken model of deprivation and lens-induced myopia.

Methods : Pupil brightness was measured when a single white or UV LED (375 nm), centered in the camera lens, was flashed. The average pixel grey level (px) in the pupil was taken as a measure of the amount of light reflected from the fundus after pupil brightness was corrected for pupil area size. Trial lenses were used to correct refractive errors to avoid isotropic photorefraction. Two CCD cameras were used, one RGB camera and the other sensitive in near UV (peak at 360 nm). Myopia was induced in one eye in ten days old male chickens (n=15) by attaching frosted plastic diffusers (form-deprivation myopia, n=10) or -7D lenses (lens-induced myopia, n=5) for seven days. The thickness of RNFL and RGCL and the thickness of the layers between the inner plexiform layer and the retinal pigment epithelium were directly measured in SD-OCT scans in alert chicks.

Results : Myopic eyes had brighter pupils in UV light, compared to controls with normal vision, no matter whether myopia was induced by diffusers or negative lenses (48 ± 8.6 vs. 27.6 ± 2.8, p<0.001 and 47 ± 6.6 vs. 27.3 ± 1.9; respectively). The retinal nerve fiber layer (RNFL) and the retinal ganglion cell layer (RGCL) in the central retina became thinner already in eyes that started to become myopic, compared to controls (31.2 ± 5.8 µm vs. 43.9 ± 2.6 µm, p<0.001 and 36.9 ± 1.2 µm vs. 44 ± 0.5 µm, respectively). No changes were observed in the other retinal layers. Decreasing RNFL thickness was significantly correlated with increasing UV reflectivity (R=0.62, p<0.001).

Conclusions : Already at the very early stages of myopia development, eyes had significantly higher UV reflectivity and thinner RNFL+RGCL compared to controls. Possible explanations for the thinning of the RNFL include reduced neural activity in retinal ganglion cells due to a poor quality of the retinal images, or interactions of the biochemical messengers controlling scleral growth with the integrity of spiking retinal neurons.

This abstract was presented at the 2019 ARVO Annual Meeting, held in Vancouver, Canada, April 28 - May 2, 2019.


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