Optical Causes of Experimental Myopia

Sivak, J. G.; Barrie, D L; Callender, M.G.; Doughty, Michael J.; Seltner, Ruth L. Pickett; West, Judith A.

doi:10.1002/9780470514023.ch10

Cited by 9 publications

(5 citation statements)

References 18 publications

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“…In vivo determination of CCT in living chicks can provide important corneal morphometric data for myopia, refractive surgery, and glaucoma research models 1,13–17 . The measurement of CCT in eyes of small living animals is difficult and is often based only on postmortem measurements taken on histological sections.…”

Section: Discussionmentioning

confidence: 99%

In vivo measurement of central corneal thickness in normal chicks (Gallus gallus domesticus) with the optical low‐coherence reflectometer

Tappeiner

Goldblum

Κatsoulis

et al. 2011

Veterinary Ophthalmology

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Section: Discussionmentioning

confidence: 99%

In vivo measurement of central corneal thickness in normal chicks (Gallus gallus domesticus) with the optical low‐coherence reflectometer

Tappeiner

Goldblum

Κatsoulis

et al. 2011

Veterinary Ophthalmology

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“…The effect of optical defocus on the pERG response was investigated with a series of defocusing lenses (−10, −5, +5 & +10 D lenses), covering the range commonly encountered in eye growth studies involving chicks (Sivak, Barrie, Callender, Doughty, Seltner & West, 1990). The effect of diffusing blur was investigated using a series of Bangerter filters (0.6, 0.2, <0.1 & light perception (LP)), which attenuate stimulus contrast and act as low pass spatial frequency filters (Tran, Chiu, Tian & Wildsoet, 2008).…”

Section: Methodsmentioning

confidence: 99%

The pattern ERG in chicks – Stimulus dependence and optic nerve section

2016

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The chick is widely used in studies of eye growth regulation and myopia. The aim of this study was to explore the utility of pattern (p)ERG as a tool to assess retinal function in such studies. Effects of optical defocus and diffusing blur, manipulations used to alter eye growth experimentally, were evaluated. PERGs were recorded from White-Leghorn chickens, using a checkerboard pattern, including 8 spatial frequencies (0.05 to 2.2 c/d SF), 13 contrast levels (1–100%), and 8 temporal reversal frequencies (0.5 to 20 Hz). The acute effects of defocus and diffusing blur were examined. Flash- and pERGs were also recorded from chicks that underwent monocular optic nerve section (ONS), to explore the contribution of retinal ganglion cells (RGCs). Measurements were made up to 6 weeks post-ONS, complemented with SD-OCT imagng. In normal chicks, the response to 1 Hz, 100% contrast stimuli showed positive- and negative-going waveforms at 43 ms (P1) and 75 ms (N95), respectively, with 0.06–0.1 c/d SF eliciting the largest P1 amplitudes of 21.9 ± 2.5 μV. Contrast levels above 5% yielded measurable P1 responses. Responses were transient and monophasic for 0.5 to 5 Hz reversal rates, with higher temporal frequencies yielding steady state responses. Defocus and diffusing blur decreased pERG amplitude across all SFs. pERG responses remained normal after ONS, despite the loss of RGCs. In conclusion, chicks show robust pERG responses, which are attenuated by defocus and diffusing blur. The pERG response is not affected by ONS, suggesting that RGCs do not contribute to the chick pERG.

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“…In animal models, the defocus phenomenon was demonstrated in chicks as early as 1990 [18]: the application of plus lenses resulted in the formation of an image in front of the retina. This imposed myopic defocus will slow the elongation speed of the eye and the thickening of the choroid, thereby effectively pushing the retina to the image plane and minimizing the imposed refractive error [19].…”

Section: Introductionmentioning

confidence: 99%

Mechanism of Myopic Defocus or Atropine for Myopia Control: Different or Similar Ways?

Sun

Chen

et al. 2022

Ophthalmic Res

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Introduction: Myopia is usually caused by excessive elongation of the eye during development. This condition is common worldwide. In clinical practice, the progression of myopia is commonly controlled through optical or drug measures, but the specific mechanisms underlying these two treatments remain unclear. To verify whether the effects of these two treatments on posterior-pole tissues are similar or different, we studied a set of common transcriptional changes in chicken models. Methods: Chicks were divided into four groups, and they were given the intervention measures of plus-lens induction, minus-lens induction, minus-lens induction with atropine injection, and minus-lens induction with saline injection. Then, the genetic changes in each tissue at the posterior pole were detected, and the results of different genes were compared. A semiquantitative real-time polymerase chain reaction (RT-PCR) method was used to further study the visually induced changes in the transcription of potential candidate genes. Results: Based on RNA-sequencing (RNA-seq) analysis of the transcriptome, we identified variations between the differentially expressed transcripts (DETs) in three tissues from the two treatment groups. Through Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analyses, eukaryotic protein translation elongation factor 1α2 (EEF1A2) was enriched in the ‘leishmaniasis’ pathway in the choroid and showed increased expression in both the plus-lens induction and injection atropine groups. The expression levels of selected genes verified by qPCR were concordant with the RNA-seq data. Conclusions: Overlapping differentially expressed mRNAs of only one-tenth could suggest a different mechanism of myopic defocus and intravitreal injection of atropine controlling myopia. EEF1A2 might play an important role in the choroid during the treatment of myopia.

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Optical Causes of Experimental Myopia

Cited by 9 publications

References 18 publications

In vivo measurement of central corneal thickness in normal chicks (Gallus gallus domesticus) with the optical low‐coherence reflectometer

In vivo measurement of central corneal thickness in normal chicks (Gallus gallus domesticus) with the optical low‐coherence reflectometer

The pattern ERG in chicks – Stimulus dependence and optic nerve section

Mechanism of Myopic Defocus or Atropine for Myopia Control: Different or Similar Ways?

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