Retinal control of lens-induced astigmatism in chicks

Popa, Anca Vanessa; Kee, Chea Su; Stell, William K.

doi:10.1016/j.exer.2020.108000

Cited by 5 publications

(4 citation statements)

References 49 publications

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“…They found that ocular growth was altered in chicks exposed to simple hyperopic or myopic astigmatic defocus, with a greater magnitude of myopia or hyperopia developing in the treated compared to the untreated fellow eye, respectively. 5 − 7 Changes in axial eye growth in response to astigmatic defocus have also been reported in chicks 8 − 14 and monkeys. 15 , 16 In the current study, changes in the macular ChT were observed in response to short-term exposure to simple myopic astigmatic defocus, providing further evidence that orientation-dependent cues associated with astigmatism also alter human ChT.…”

Section: Discussionmentioning

confidence: 63%

“…A recent study in chicks also provides evidence for local retinal mechanisms contributing to the modulation of eye growth associated with astigmatic defocus. 14 Although orientation selectivity in the human retina has not been confirmed, the vertical-horizontal asymmetry in the local spacing of foveal cone photoreceptors (with less spacing vertically than horizontally) 49 may contribute to orientation selectivity occurring early in retinal light sampling. 50 There is also compelling evidence from mice and macaques demonstrating retinal amacrine 51 and ganglion cells 52 exhibiting preferential sensitivity to vertically or horizontally oriented features.…”

Section: Discussionmentioning

confidence: 99%

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Astigmatic Defocus Leads to Short-Term Changes in Human Choroidal Thickness

Hoseini-Yazdi

Vincent

Read

et al. 2020

Invest. Ophthalmol. Vis. Sci.

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To examine the choroidal thickness (ChT) response to short-term with-the-rule (WTR) and against-the-rule (ATR) simple myopic astigmatic defocus, with the response to spherical myopic defocus and clear vision used as control conditions. METHODS. The left eye of 18 healthy adults aged 28 ± 6 years was exposed to clear vision, +3 D spherical myopic defocus, +3 D × 180 WTR, or +3 D × 90 ATR astigmatic defocus for 60 minutes, over four randomly ordered visits, while their right eye was optimally corrected. The macular ChT was measured with optical coherence tomography along the vertical and horizontal meridians before and after 20, 40, and 60 minutes of defocus. RESULTS. After 60 minutes of defocus, ChT increased by +8 ± 5 μm (P < 0.001) with spherical myopic defocus, but varied with simple myopic astigmatic defocus, depending on the axis of astigmatism (P < 0.001), increasing by +5 ± 6 μm (P = 0.037) with WTR and decreasing by −4 ± 5 μm (P = 0.011) with ATR astigmatic defocus. These changes were similar across the vertical and horizontal meridians (P = 0.22). The ChT changes were greater than the change during the clear vision control condition (−1 ± 4 μm) for WTR (+5 ± 5 μm, P = 0.002) but not ATR (−4 ± 6 μm, P = 0.09) astigmatic defocus. CONCLUSIONS. These results provide insights into the human ChT response to short-term astigmatic defocus and highlight a potential difference in the myopiagenic signal associated with the orientation of astigmatic blur.

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Section: Discussionmentioning

confidence: 63%

Section: Discussionmentioning

confidence: 99%

Astigmatic Defocus Leads to Short-Term Changes in Human Choroidal Thickness

Hoseini-Yazdi

Vincent

Read

et al. 2020

Invest. Ophthalmol. Vis. Sci.

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“…Astigmatism is a frequently found ocular disease, but this visual defect is a correctable refractive error [ 51 ]. It is due to the incompatibility between corneal or lens curvature error, leading to blurred distance and near vision [ 52 , 53 ]. Females of the current study participants had higher CC than their male counterparts.…”

Section: Discussionmentioning

confidence: 99%

A Study Linking Axial Length, Corneal Curvature, and Eye Axis With Demographic Characteristics in the Emmetropic Eyes of Bangladeshi People

Benzir¹,

Afroze²,

Zahan³

et al. 2022

Cureus

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BackgroundAxial length (AL) and corneal curvature (CC) are one of the furthest critical parameters for optometry and oculoplastic surgery. These two variables are crucial in biometry for accurately measuring the power of the intraocular lens in cataract surgery. This research aimed to determine the association linking axial length and corneal curvature with demographic characteristics in emmetropic eyes of Bangladeshi people. MethodsThis descriptive cross-sectional research was carried out among 200 emmetropic eyes of Bangladeshi people attending the Department of Ophthalmology at Rajshahi Medical College, Bangladesh, with different eye conditions, between July 2017 and June 2018. Data was gathered by conducting person-to-person interviews, checking visual activity using the Snellen chart, and measuring corneal curvature using an autokeratometer and axial eyeball length using A-scan ultrasonography. ResultsA total of 200 attendances were studied, 90 males and 110 females. All were emmetropic. The age range was 21-52 years, and the highest contributors were in the 21-30-year age group. The association between right axial length and right corneal curvature shows a negative relation among both sexes. It was -0.61 (βcoefficient (β-coff)), and highly significant in females at -0.89 (β-coff). Additionally, the association between left axial length and left corneal curvature shows a negative relation of -0.65 (β-coff), which was again highly significant in females at -0.87 (β-coff). Both were not significant in males. There was no significant association linking axial length and eye axis in both sexes. The multivariate regression model was used to assess the p-value, and the regression model was adjusted by age. ConclusionOptical parametric measurement is a noninvasive diagnostic and assessment tool that might help in the actual measurement of intraocular lens implantation in cataract surgery and may also provide supplementary information to the researcher domain.

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“…A recent animal study, which involved destruction of retinal amacrine and bipolar cells by excitotoxin mixture, revealed that astigmatism compensation is mediated by the visual processing by the retina, as the cell obliteration confirmed halted astigmatism development. 52 It has been reported that the retina of many vertebrates, including primate, 53 , 54 cat, 55 – 57 rodent, 58 – 61 and rabbit, 62 , 63 comprises ganglion and amacrine cells that are orientation-selective, responding robustly to a preferred orientation, but weakly to the orthogonal one. Further studies are warranted to understand how the cornea, crystalline lens, and retinal signals interact and contribute to the refractive astigmatic changes after short-term exposure to astigmatic blur.…”

Section: Discussionmentioning

confidence: 99%

Bi-directional Refractive Compensation for With-the-Rule and Against-the-Rule Astigmatism in Young Adults

Chan

Shik

Kwok

et al. 2022

Invest. Ophthalmol. Vis. Sci.

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Purpose The purpose of this study was to investigate the short-term effect of imposing astigmatism on the refractive states of young adults. Methods Nineteen visually healthy low-astigmatic young adults (age = 20.94 ± 0.37 years; spherical-equivalent errors [M] = −1.47 ± 0.23 diopters [D]; cylindrical errors = −0.32 ± 0.05 D) were recruited. They were asked to wear a trial frame with treated and control lenses while watching a video for an hour. In three separate visits, the treated eye was exposed to one of three defocused conditions in random sequence: (1) with-the-rule (WTR) astigmatism = +3.00 DC × 180 degrees; (2) against-the-rule (ATR) astigmatism = +3.00 DC × 90 degrees; and (3) spherical defocus (SPH) = +3.00 DS. The control eye was fully corrected optically. Before and after watching the video, non-cycloplegic autorefraction was performed over the trial lenses. Refractive errors were decomposed into M, J0, and J45 astigmatism. Interocular differences in refractions (treated eye – control eye) were analyzed. Results After participants watched the video with monocular astigmatic defocus for an hour, the magnitude of the J0 astigmatism was significantly reduced by 0.25 ± 0.10 D in both WTR (from +1.53 ± 0.07 D to +1.28 ± 0.09 D) and 0.39 ± 0.15 D in ATR conditions (from −1.33 ± 0.06 D to −0.94 ± 0.18 D), suggesting an active compensation. In contrast, changes in J0 astigmatism were not significant in the SPH condition. No compensatory changes in J45 astigmatism or M were found under any conditions. Conclusions Watching a video for an hour with astigmatic defocus induced bidirectional, compensatory changes in astigmatic components, suggesting that refractive components of young adults are moldable to compensate for orientation-specific astigmatic blur over a short period.

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Retinal control of lens-induced astigmatism in chicks

Cited by 5 publications

References 49 publications

Astigmatic Defocus Leads to Short-Term Changes in Human Choroidal Thickness

Astigmatic Defocus Leads to Short-Term Changes in Human Choroidal Thickness

A Study Linking Axial Length, Corneal Curvature, and Eye Axis With Demographic Characteristics in the Emmetropic Eyes of Bangladeshi People

Bi-directional Refractive Compensation for With-the-Rule and Against-the-Rule Astigmatism in Young Adults

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