High myopia induced by form deprivation is associated with altered corneal biomechanical properties in chicks

Kang, Byung Soo; Wang, Li Ke; Zheng, Yongping; Guggenheim, Jeremy A.; Stell, William K.; Kee, Chea Su

doi:10.1371/journal.pone.0207189

Cited by 27 publications

(19 citation statements)

References 52 publications

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“…For instance, the crystalline lens thickness and corneal refractive power decrease in proportion to AL elongation ( Meng et al, 2011 ). However, when the eye is elongated further, pathological changes start to appear ( Backhouse and Phillips, 2010 ; Kang et al, 2018 ). When the eye progresses to a pathological state, the traction resulting from the AL elongation is mainly from the posterior pole with minimal or no collaboration with the other parts of the globe; hence, the changes in the anterior structures tend to be relatively stable and irrelevant to the excessive AL elongation ( Larsen, 1971 ; Khokhar et al, 2018 ).…”

Section: Discussionmentioning

confidence: 99%

The Effect of Axial Length Elongation on Corneal Biomechanical Property

Hua

Zhang

et al. 2021

Front. Bioeng. Biotechnol.

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Background: To investigate the correlation between the corneal biomechanical parameter stress-strain index (SSI) and axial length (AL) in moderately elongated eye (MEE) and severely elongated eye (SEE).Methods: This study included 117 eyes from 117 participants. Among them, 59 (50.4%) had MEE (AL<26 mm) and 58 (49.6%) had SEE (AL≥26 mm). AL was measured using Lenstar LS-900, and central corneal thickness (CCT) and anterior chamber volume (ACV) were measured using Pentacam. SSI was measured via corneal visualisation Scheimpflug technology (Corvis ST). Kolmogorov-Smirnov test, Student’s t-test, and Pearson and partial correlation analyses were used for statistical analyses.Results: The mean (±SD) SSI was 1.08 ± 0.15 in the MEE group and 0.92 ± 0.13 in the SEE group (p < 0.01). SSI was positively correlated with age (MEE: r = 0.326, p < 0.05; SEE: r = 0.298, p < 0.05) in both groups; it was negatively correlated with AL (r = −0.476, p < 0.001) in the MEE group but not in the SEE group (p > 0.05). CCT was negatively correlated with AL (r = −0.289, p < 0.05) and ACV positively correlated with AL (r = 0.444, p < 0.001) in the MEE group. Neither CCT nor ACV was correlated with AL (p > 0.05) in the SEE group.Conclusion: Corneal biomechanical parameter SSI, which represents the stiffness of corneal tissue, was lower in the SEE group than in the MEE group. When analyzed separately, SSI was negatively correlated with AL in the MEE group, but not in the SEE group, which may provide insight into different ocular growth patterns between lower myopia and higher myopia.

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Section: Discussionmentioning

confidence: 99%

The Effect of Axial Length Elongation on Corneal Biomechanical Property

Hua

Zhang

et al. 2021

Front. Bioeng. Biotechnol.

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“…At the end of the treatment period, refractive state, corneal curvature, and ocular axial dimensions were measured by a modified Hartinger coincidence refractometer 47 (Jena coincidence Refractometer, Model 110; Carl Zeiss Meditec, Jena, Germany), custom-made Placido-ring videokeratography, 48 and high-resolution A-scan ultrasonography, 49 , 50 respectively. The refractive state was measured for all birds, whereas corneal curvature and ocular axial dimensions were measured for subsets of birds.…”

Section: Methodsmentioning

confidence: 99%

“…Eyelids of anesthetized chicks were held open with a speculum while three measurements were taken along the pupillary axis. Each measurement consisted of 50 echograms, and these were averaged as previously described 49 , 50 to obtain the axial dimensions of individual ocular components. The axial length was defined as the sum of the distance from anterior cornea to the posterior sclera.…”

Section: Methodsmentioning

confidence: 99%

Early Astigmatism Can Alter Myopia Development in Chickens

Vyas

Kee

2021

Invest. Ophthalmol. Vis. Sci.

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Purpose To determine the effects of optically imposed astigmatism on myopia development in chickens. Methods Chicks were randomly assigned to wear either spherical (−10D, “LIM”, n = 14) or sphero-cylindrical lenses ( n ≥ 19 in each group) monocularly for a week from 5 days of age. All lenses imposed the same magnitude of spherical-equivalent hyperopic defocus (−10D), with the two astigmatic magnitudes (−8D or −4D) and four axes (45°, 90°, 135°, or 180°) altered to simulate four subtypes of clinical astigmatism. At the end of the treatment, refractive state was measured for all birds, whereas ocular axial dimensions and corneal curvature were measured for subsets of birds. Results Sphero-cylindrical lens wear produced significant impacts on nearly all refractive parameters ( P < 0.001), resulting in myopic-astigmatic errors in the treated eyes. Compared to LIM, the presence of astigmatic blur induced lower myopic error (all except L180 group, P < 0.001) but with higher refractive astigmatism (all P < 0.001) in birds treated with sphero-cylindrical lenses. Distributions of the refractive, axial, and corneal shape parameters in the sphero-cylindrical lens-wear groups indicated that the astigmatic blur had directed the eye growth toward the least hyperopic image plane, with against-the-rule (ATR) and with-the-rule (WTR) astigmatisms typically inducing differential biometric changes. Conclusions The presence of early astigmatism predictably altered myopia development in chicks. Furthermore, the differential effects of WTR and ATR astigmatisms on anterior and posterior segment changes suggest that the eye growth mechanism is sensitive to the optical properties of astigmatism.

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“…The increase in ACD of FDEP eyes compared to controls was expected and only accounted for 19.8% and 30.3% of the overall axial elongation on D14 under BEW and SW lights, respectively. Conversely, corneal thinning have only recently been reported in form-deprivation models of chickens 67 , but is not unusual in humans 68 . Interestingly, anterior segment alterations during form-deprivation were not corrected (especially CCT under SW) during the 14 days recovery phase and were possibly epiphenomena of excessive ocular or posterior segment growth in an ordinarily growing orbit.…”

Section: Discussionmentioning

confidence: 98%

Ocular growth and metabolomics are dependent upon the spectral content of ambient white light

Najjar

Barca

Barathi

et al. 2021

Sci Rep

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Myopia results from an excessive axial growth of the eye, causing abnormal projection of remote images in front of the retina. Without adequate interventions, myopia is forecasted to affect 50% of the world population by 2050. Exposure to outdoor light plays a critical role in preventing myopia in children, possibly through the brightness and blue-shifted spectral composition of sunlight, which lacks in artificial indoor lighting. Here, we evaluated the impact of moderate levels of ambient standard white (SW: 233.1 lux, 3900 K) and blue-enriched white (BEW: 223.8 lux, 9700 K) lights on ocular growth and metabolomics in a chicken-model of form-deprivation myopia. Compared to SW light, BEW light decreased aberrant ocular axial elongation and accelerated recovery from form-deprivation. Furthermore, the metabolomic profiles in the vitreous and retinas of recovering form-deprived eyes were distinct from control eyes and were dependent on the spectral content of ambient light. For instance, exposure to BEW light was associated with deep lipid remodeling and metabolic changes related to energy production, cell proliferation, collagen turnover and nitric oxide metabolism. This study provides new insight on light-dependent modulations in ocular growth and metabolomics. If replicable in humans, our findings open new potential avenues for spectrally-tailored light-therapy strategies for myopia.

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High myopia induced by form deprivation is associated with altered corneal biomechanical properties in chicks

Cited by 27 publications

References 52 publications

The Effect of Axial Length Elongation on Corneal Biomechanical Property

The Effect of Axial Length Elongation on Corneal Biomechanical Property

Early Astigmatism Can Alter Myopia Development in Chickens

Ocular growth and metabolomics are dependent upon the spectral content of ambient white light

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