June 2023
Volume 64, Issue 8
Open Access
ARVO Annual Meeting Abstract  |   June 2023
IOP-Induced Peripapillary Tissue Thinning in Emmetropic and High Myopic Juvenile Tree Shrews
Author Affiliations & Notes
  • Rafael Grytz
    Department of Ophthalmology and Visual Sciences, The University of Alabama at Birmingham, Birmingham, Alabama, United States
  • Mustapha El Hamdaoui
    Department of Ophthalmology and Visual Sciences, The University of Alabama at Birmingham, Birmingham, Alabama, United States
  • Preston A Fuchs
    Department of Ophthalmology and Visual Sciences, The University of Alabama at Birmingham, Birmingham, Alabama, United States
  • Mahmoud Tawfik KhalafAllah
    Vision Science Graduate Program, The University of Alabama at Birmingham, Birmingham, Alabama, United States
  • Mokshad Gaonkar
    Department of Biostatistics, The University of Alabama at Birmingham, Birmingham, Alabama, United States
  • Brian C. Samuels
    Department of Ophthalmology and Visual Sciences, The University of Alabama at Birmingham, Birmingham, Alabama, United States
  • Footnotes
    Commercial Relationships   Rafael Grytz iVeena Delivery Systems, Code C (Consultant/Contractor), Heidelberg Engineering provided Spectralis OCT2 at no cost , Code F (Financial Support); Mustapha El Hamdaoui None; Preston Fuchs None; Mahmoud KhalafAllah None; Mokshad Gaonkar None; Brian Samuels Heidelberg Engineering provided Spectralis OCT2 at no cost, Code F (Financial Support)
  • Footnotes
    Support  NIH Grants R01-EY027759, P30 EY0039039; EyeSight Foundation of Alabama; Research to Prevent Blindness. We like to thank Heidelberg Engineering for providing the Spectralis OCT2 at no cost.
Investigative Ophthalmology & Visual Science June 2023, Vol.64, 2856. doi:
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    • Get Citation

      Rafael Grytz, Mustapha El Hamdaoui, Preston A Fuchs, Mahmoud Tawfik KhalafAllah, Mokshad Gaonkar, Brian C. Samuels; IOP-Induced Peripapillary Tissue Thinning in Emmetropic and High Myopic Juvenile Tree Shrews. Invest. Ophthalmol. Vis. Sci. 2023;64(8):2856.

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

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Abstract

Purpose : To investigate the effect of high myopia on IOP-induced peripapillary tissue thinning in juvenile tree shrews.

Methods : Two groups of juvenile tree shrews were studied: (i) binocular normal vision (spherical equivalent refraction 0.34 ± 0.97 D, n = 10 eyes) and (ii) experimental high myopia in one eye (-9.76 ± 1.19 D, n = 6 eyes) while the other eye served as control (0.39 ± 0.88 D, n = 6 eyes). Animals were anesthetized and the anterior chamber was cannulated to control IOP through a hydrostatic column. Forty-eight radial optical coherence tomography B-scans centered on the optic nerve head (ONH) were obtained at four IOP levels: 5, 15, 30, 45 mmHg. The sclera, choroid-retinal pigment epithelium complex (Ch-RPE), retinal nerve fiber layer (RNFL) and remaining retinal layers (RRL) were automatically segmented and reconstructed in 3D after nonlinear distortion correction of each B-scan. The peripapillary tissue thickness was calculated over a 50 µm band located 1000 µm away from the ONH center. Results were analyzed as relative thickness changes from baseline IOP. Differences among groups were assessed using a marginal mean model accounting for repeated and correlated observations. A quadratic term was incorporated into the model to account for nonlinear trends in tissue thinning with IOP. The significance level was set to 0.05 and Bonferroni correction was applied.

Results : IOP-induced thinning of all tissues was significantly increased in high myopia compared to control eyes (Fig. 1). Scleral and RRL thinning was also significantly different between high myopia and normal eyes. Across all groups, relative IOP-induced thinning was significantly lower in the retinal layers compared to Ch-RPE and sclera. A sectorial analysis (Fig. 2) revealed that high myopia introduced an asymmetric thinning response, where the sclera and RRL thinned significantly more in sectors that were closest to the posterior pole. A similar thinning pattern was not seen in the RNFL and Ch-RPE.

Conclusions : Peripapillary tissues respond very differently to acute IOP elevation in juvenile tree shrews, where the retina seems to be shielded from IOP-induced thinning but not the choroid and sclera. Juvenile high myopia increased the susceptibility of all peripapillary tissues to IOP-induced thinning and introduced an asymmetric thinning pattern across sectors, which may contribute to increased risk for glaucoma.

This abstract was presented at the 2023 ARVO Annual Meeting, held in New Orleans, LA, April 23-27, 2023.

 

 

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