Inducing ametropias in hatchling chicks by defocus—Aperture effects and cylindrical lenses

Irving, Elizabeth L.; Callender, M.G.; Sivak, J. G.

doi:10.1016/0042-6989(94)00235-e

Cited by 74 publications

(58 citation statements)

References 14 publications

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“…Some animal studies have assessed the effect of applying cylindrical lenses to the central retina of developing animals and produced mixed results. Irving et al 47 found evidence for a partial compensatory astigmatic growth in chick eyes; the effectiveness of the compensation varied with the orientation of the axis of the cylinder. In contrast, Schmid and Wildsoet 48 found no astigmatic compensation in the growing chick eye: rather chicks appeared to ''emmetropize'' to the meridian with the greater myopic defocus, irrespective of the cylinder axis.…”

Section: Discussionmentioning

confidence: 99%

Peripheral Refractive Changes Associated with Myopia Progression

Radhakrishnan

Allen

Calver

et al. 2013

Invest. Ophthalmol. Vis. Sci.

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PURPOSE.To evaluate the changes in peripheral refraction profiles associated with myopia progression and treatment modalities used in the Cambridge Anti-Myopia Study. METHODS.One hundred and seventy-seven myopes in the age range of 14 to 22 years were enrolled in the study. The mean spherical equivalent refractive error was À3.12 6 1.87 diopters (D) and the refractive error of each participant was corrected with contact lenses. The participants were randomly assigned to one of four treatment groups, which included: altered spherical aberration and vision training, altered spherical aberration only, vision training only, and control. Peripheral refractive error was measured using an open field autorefractor in the central 608 of the retina in 108 steps. The refractive error was measured using cycloplegic autorefraction. Two-year refractive progression data and initial peripheral refraction measurements were available in 113 participants. Measurements of peripheral refraction and cycloplegic refraction were obtained at three visits over 2 years in 12-month intervals for 92 participants.RESULTS. All subjects showed a relative peripheral hyperopia, especially in the nasal retina. A limited magnitude of myopia progression of À0.34 6 0.36 D over 2 years was found in each of the four groups on average. There were no significant differences in the rate of progression between any of the treatment groups (P > 0.05). Initial peripheral J45 astigmatic refractive error at 208 and 308 in the nasal retina was weakly correlated with progression of myopia over 2 years (r ¼À0.27, P ¼ 0.004 and r ¼À0.20, P ¼ 0.040, respectively; n ¼ 113). The change in spherical equivalent peripheral refractive error at 308 nasal retina over time was also significantly correlated with progression of myopia especially at 24 months (r ¼À0.24, P ¼ 0.017, n ¼ 92). CONCLUSIONS.Relative peripheral hyperopia is associated with myopia. Myopia progression may be weakly linked to changes in the peripheral refraction profiles in the nasal retina.However, a causative link between peripheral refractive error and myopia progression could not be established. (Invest

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Section: Discussionmentioning

confidence: 99%

Peripheral Refractive Changes Associated with Myopia Progression

Radhakrishnan

Allen

Calver

et al. 2013

Invest. Ophthalmol. Vis. Sci.

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“…111 Plus lenses have been shown to act inversely to decrease the AL elongation rate in tree shrews 112 and chicks. 113 The idea of recovery from induced myopia emerged when it was reported that induced chick axial elongation due to form deprivation showed recovery when patterned light was restored in young animals. 114 These researchers also suggested that this recovery is inversely related to age and hinted at the existence of an active emmetropization mechanism.…”

Section: Animal Model Studies Related To Myopia and Eye Growthmentioning

confidence: 99%

Complex Trait Genetics of Refractive Error

Young¹

2007

Arch Ophthalmol

180

127

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“…Moreover, optically imposing either myopia or hyperopia in young animals with spherical lenses results in compensating axial ametropias that are dependent on the sign and power of the treatment lenses (e.g., rhesus monkeys,24 marmosets,25 tree shrews, 26 and chickens27). However, in part because experimentally induced refractive errors have traditionally been expressed in a spherical-equivalent format (i.e., the averaged correction for the two principal astigmatic meridians), only a few studies in chickens have previously noted an association between astigmatism and either axial hyperopia or myopia.28, 29 The purpose of this study was to determine if vision-dependent alterations in axial growth also lead to the development of astigmatism in primates. Specifically, we examined the frequency and characteristics of astigmatism in infant monkeys that developed axial ametropias in response to a variety of different types of altered visual experience.…”

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confidence: 99%

Astigmatism in Monkeys with Experimentally Induced Myopia or Hyperopia

Kee¹,

Hung²,

Qiao-Grider

et al. 2005

Optometry and Vision Science

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Purpose-Astigmatism is the most common ametropia found in humans and is often associated with large spherical ametropias. However, little is known about the etiology of astigmatism or the reason(s) for the association between spherical and astigmatic refractive errors. This study examines the frequency and characteristics of astigmatism in infant monkeys that developed axial ametropias as a result of altered early visual experience.Methods-Data were obtained from 112 rhesus monkeys that experienced a variety of lens-rearing regimens that were intended to alter the normal course of emmetropization. These visual manipulations included form deprivation (n = 13); optically imposed defocus (n = 48); and continuous ambient lighting with (n = 6) or without optically imposed defocus (n = 6). In addition, data from 19 control monkeys and 39 infants reared with an optically imposed astigmatism were used for comparison purposes. The lens-rearing period started at approximately 3 weeks of age and ended by 4 to 5 months of age. Refractive development for all monkeys was assessed periodically throughout the treatment and subsequent recovery periods by retinoscopy, keratometry, and A-scan ultrasonography.Results-In contrast to control monkeys, the monkeys that had experimentally induced axial ametropias frequently developed significant amounts of astigmatism (mean refractive astigmatism = 0.37 ± 0.33 D [control] vs. 1.24 ± 0.81 D [treated]; two-sample t-test, p < 0.0001), especially when their eyes exhibited relative hyperopic shifts in refractive error. The astigmatism was corneal in origin (Pearson's r; p < 0.001 for total astigmatism and the JO and J45 components), and the axes of the astigmatism were typically oblique and bilaterally mirror symmetric. Interestingly, the astigmatism was not permanent; the majority of the monkeys exhibited substantial reductions in the amount of astigmatism at or near the end of the lens-rearing procedures.Conclusions-In infant monkeys, visual conditions that alter axial growth can also alter corneal shape. Similarities between the astigmatic errors in our monkeys and some astigmatic errors in humans suggest that vision-dependent changes in eye growth may contribute to astigmatism in humans. Keywordsastigmatism; ametropia; refractive error; primate; emmetropization Astigmatism is the most common refractive error, occurring frequently in both healthy (for a review, see reference 1) and diseased eyes.2-4 For instance, in a recent multicentered, schoolbased study (ages 5-17 years), significant amounts of astigmatism were more prevalent (≥1.0 Chea-Su Kee, University of Houston, College of Optometry, 505 J Davis Armistead Bldg. Houston, Texas 77204-2020, e-mail: ckee@mail.uh.edu NIH Public Access Author ManuscriptOptom Vis Sci. Author manuscript; available in PMC 2007 March 5. Published in final edited form as:Optom Vis Sci. 2005 April ; 82(4): 248-260. NIH-PA Author ManuscriptNIH-PA Author Manuscript NIH-PA Author Manuscript D, 28.4%) than myopia (≥−0.75 D, 9.2%) or hyperopia (≥+1.2...

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Inducing ametropias in hatchling chicks by defocus—Aperture effects and cylindrical lenses

Cited by 74 publications

References 14 publications

Peripheral Refractive Changes Associated with Myopia Progression

Peripheral Refractive Changes Associated with Myopia Progression

Complex Trait Genetics of Refractive Error

Astigmatism in Monkeys with Experimentally Induced Myopia or Hyperopia

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