June 2023
Volume 64, Issue 8
Open Access
ARVO Annual Meeting Abstract  |   June 2023
The Axis of Astigmatic Blur Affects the Magnitude of Cylindrical-Lens Induced Astigmatism Across the Visual Field in Chickens
Author Affiliations & Notes
  • Patience Ansomah Ayerakwah
    School of Optometry, The Hong Kong Polytechnic University, Kowloon, Hong Kong
  • Byung Soo Kang
    Centre for Eye and Vision Research Limited, Hong Kong, Hong Kong
  • Yuanyuan Liang
    School of Optometry, The Hong Kong Polytechnic University, Kowloon, Hong Kong
  • Henry Ho-lung Chan
    School of Optometry, The Hong Kong Polytechnic University, Kowloon, Hong Kong
    Research Centre for SHARP Vision, Hong Kong
  • Chea-Su Kee
    School of Optometry, The Hong Kong Polytechnic University, Kowloon, Hong Kong
    Research Centre for SHARP Vision, Hong Kong
  • Tsz Wing Leung
    School of Optometry, The Hong Kong Polytechnic University, Kowloon, Hong Kong
    Research Centre for SHARP Vision, Hong Kong
  • Footnotes
    Commercial Relationships   Patience Ayerakwah None; Byung Kang None; Yuanyuan Liang None; Henry Chan None; Chea-Su Kee None; Tsz Wing Leung None
  • Footnotes
    Support  Start-up Fund for RAPs under the Strategic Hiring Scheme (P0035517)
Investigative Ophthalmology & Visual Science June 2023, Vol.64, 961. doi:
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      Patience Ansomah Ayerakwah, Byung Soo Kang, Yuanyuan Liang, Henry Ho-lung Chan, Chea-Su Kee, Tsz Wing Leung; The Axis of Astigmatic Blur Affects the Magnitude of Cylindrical-Lens Induced Astigmatism Across the Visual Field in Chickens. Invest. Ophthalmol. Vis. Sci. 2023;64(8):961.

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

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Abstract

Purpose : Astigmatism is a common refractive error in children. A recent study has reported that the retinal signaling pathway is involved in experimentally induced astigmatism in chicks. However, whether the retina across the visual field is equally sensitive to astigmatic cues remains unclear. This study investigated the impacts of the astigmatic axis on astigmatism development by exposing the retina of restricted regions to two common astigmatic subtypes.

Methods : With-The-Rule (WTR) and Against-The-Rule (ATR) astigmatisms were optically imposed, monocularly, by using crossed-cylindrical lenses (+2.00DS/-4.00DC) of 90° or 180°, respectively, from post-hatching day 5 (P5) for a week. White Leghorn chicks were randomly assigned to wear these lenses covering different retinal regions:
Full-Field (FF): WTR, n = 9; ATR, n = 9
Horizontal Field (HF): WTR, n = 8; ATR, n = 10
Vertical Field (VF): WTR, n = 9; ATR, n = 7
The remaining visual field in the HF and VF groups were blocked by a black occluder (see Fig 1). Objective refraction was conducted at the end of the treatment period using a modified Hartinger refractometer.

Results : Regardless of where the visual field was exposed, both WTR and ATR conditions induced significant refractive astigmatism in treated eyes when compared to untreated fellow eyes (p ≤ 0.02). Comparing the refractive astigmatism (inter-ocular difference = treated eye –control eye) across groups showed that WTR condition (FF: -2.28±0.73D; HF: -2.50±1.36D; VF: -2.50±0.52D) generally induced higher magnitudes of astigmatism than ATR condition (FF: -0.81±0.51D; HF: -1.75±0.93D; VF: -0.93±0.75 D). The differences were statistically significant for all (p < 0.001) except the HF condition (p = 0.19). In the ATR condition, the induced astigmatism was significantly higher in the HF than in the FF conditions (p = 0.03), but the differences between VF and the other two visual field conditions were insignificant (p ≥ 0.09). No significant differences in the astigmatisms induced were found in the WTR condition across the three visual field conditions (p ≥ 0.87).

Conclusions : WTR astigmatism, either presented full-field or hemifield, appears to be more potent than ATR astigmatism in inducing astigmatism development in chicks.

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

 

A Horizontal field lens that exposes the horizontal visual field to imposed astigmatism while covering the vertical visaul field

A Horizontal field lens that exposes the horizontal visual field to imposed astigmatism while covering the vertical visaul field

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