The role of optical defocus in regulating refractive development in infant monkeys

Smith, Earl L.; Hung, Li-Fang

doi:10.1016/s0042-6989(98)00229-6

Cited by 337 publications

(320 citation statements)

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“…23,24 The same occurs if one puts a positive lens over the eye in chicks and monkeys. 25,26 The range of lens powers compensated for is greater in chicks than in monkeys, although monkeys can also compensate for stronger lenses if the lens power is stepped up gradually. 25,27 Similar mechanism may also be active in humans, however this entails further research.…”

Section: Discussionmentioning

confidence: 99%

Ciliary body thickness in unilateral high axial myopia

Müftüoğlu

Hoşal

Zílelíoğlu

2008

Eye

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Purpose To compare the thickness of the ciliary bodies of eyes with unilateral high axial myopia with their relatively normal fellow eyes. Methods A total of 19 patients with unilateral high axial length (AL) were included in the study. Mean patient age was 28. 4±10.4 (11-44) years. All eyes underwent ultrasound biometry to measure the AL, and ultrasound biomicroscopy to measure the anterior chamber depth, ciliary body thickness (CBT), and ciliary process thickness (CPT), ciliary muscle thickness (CMT). The results were compared between each subject's high myopic eye and relatively normal fellow eye. Results The mean AL was 27.24±1.52 mm (range: 25.16-30.21 mm) in high myopic eyes and 23.64 ± 0.86 mm (range: 22.47-25.10 mm) in normal fellow eyes. The median ± 95% confidence interval of CBT, CPT, and CMT was 1.350±0.034, 0.626±0.072, and 0.698±0.057 mm, respectively, in high myopic eyes and 1.211±0.050, 0.535±0.064, and 0.644±0.065 mm, respectively, in normal fellow eyes. The anterior chamber depth, CBT, CPT, and CMT were significantly higher in myopic eyes compared with their relatively normal fellow eyes (Po0.05). CMT significantly increased with age in both groups (Po0.05). There was no significant correlation between age and CBT in both the groups (P40.05). Conclusion The CBT, CMT, and CPT are significantly higher in eyes with unilateral high axial myopia than in their relatively normal fellow eyes.

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Section: Discussionmentioning

confidence: 99%

Ciliary body thickness in unilateral high axial myopia

Müftüoğlu

Hoşal

Zílelíoğlu

2008

Eye

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“…[27][28][29][30][31][32][33] In particular, the negative-powered lenses imposed relative hyperopia on the treated eyes, which in response became more myopic than their fellow control eyes. In contrast, the positivepowered lenses imposed relative myopia, which initiated relative hyperopic shifts in the treated eye refractive errors.…”

Section: Refractive Development Is Regulated By Optical Defocusmentioning

confidence: 99%

“…Specifically, the myopia was caused by an increase in the vitreous chamber elongation rate. 29 The hyperopic changes were due to a reduction in vitreous chamber elongation rate coupled with the normal reduction in corneal and crystalline lens power. 29 Monocular experiments like those illustrated in Figure 1 provide in-animal controls for many factors that could influence ocular growth (eg, genetic factors) and demonstrate that refractive development is largely independent in the two eyes.…”

Section: Refractive Development Is Regulated By Optical Defocusmentioning

confidence: 99%

“…The hyperopic shifts come about in young animals because reductions in axial growth occur in concert with the normal maturational decreases in corneal and lens power. 29 However, corneal power reaches adult levels very early in life and lens power decreases very slowly in adolescents, normally reaching adult values relatively early in life. 38,39 As a consequence, even viewing conditions that reduce or stop axial elongation rates will not produce hyperopic shifts because the total refracting power of the eye is stable and other mechanisms such as changes in choroidal thickness are small in primates.…”

Section: Refractive Development Is Regulated By Optical Defocusmentioning

confidence: 99%

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Visual regulation of refractive development: insights from animal studies

Smith

Hung

Arumugam

2013

Eye

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Investigations employing animal models have demonstrated that ocular growth and refractive development are regulated by visual feedback. In particular, lens compensation experiments in which treatment lenses are used to manipulate the eye's effective refractive state have shown that emmetropization is actively regulated by signals produced by optical defocus. These observations in animals are significant because they indicate that it should be possible to use optical treatment strategies to influence refractive development in children, specifically to slow the rate of myopia progression. This review highlights some of the optical performance properties of the vision-dependent mechanisms that regulate refractive error development, especially those that are likely to influence the efficacy of optical treatment strategies for myopia. In this respect, the results from animal studies have been very consistent across species; however, to facilitate extrapolation to clinical settings, results are presented primarily for nonhuman primates. In agreement with preliminary clinical trials, the experimental data show that imposed myopic defocus can slow ocular growth and that treatment strategies that influence visual signals over a large area of the retina are likely to be most effective. Eye (2014) 28, 180-188; doi:10.1038/eye.2013.277; published online 13 December 2013Keywords: myopia; hyperopia; defocus; emmetropization Curtin 1 credits Kepler with being one of the first vision scientists to recognize the association between near work and myopia and for hypothesizing that myopia was an adaptation to near work. Although these seminal observations (circa 1610) have been replicated numerous times and much has been learnt about potential risk factors for the development of common forms of myopia, centuries of research on myopia in humans have failed to provide a clear indication of what it is about near work that promotes the development of myopia or to identify the physiological mechanisms that promote myopia in children as a result of chronic near work. However, beginning in the 1960s, research employing animal models was greatly expanded and began to provide new insights into the effects of visual experience on ocular growth and refractive development.The nature of the visual manipulations that have been employed to characterize refractive development in animals fall into three broad categories. The first category involved either natural or imposed restrictions in viewing distance and was largely motivated by the near work hypothesis. For example, comparisons of refractive errors between feral and domesticated or laboratory-reared animals supported the idea that environments that restrict viewing distance are myopiagenic. 2,3 However, these studies suffered from many of the same confounding issues associated with human studies. 4 A more controlled line of research was begun by Levinsohn 5 and continued most notably by Young, 6-9 who demonstrated that monkeys reared in environments with a maximum viewing distance o...

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“…This knowledge of the accommodation mechanism and its stimulus could improve our understanding of the emmetropisation mechanism, since studies on animals and humans show that the process of long‐term growth and development of the eye (emmetropisation) responds to the direction of defocus, i.e., the same optical signals that control short term defocus adaptation (dynamic accommodation) also could control long‐term emmetropisation 1, 11, 30, 31, 32, 33, 34…”

Section: Discussionmentioning

confidence: 99%

Human eyes do not need monochromatic aberrations for dynamic accommodation

Bernal-Molina

Marín-Franch

Águila-Carrasco

et al. 2017

Ophthalmic Physiologic Optic

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PurposeTo determine if human accommodation uses the eye's own monochromatic aberrations to track dynamic accommodative stimuli.MethodsWavefront aberrations were measured while subjects monocularly viewed a monochromatic Maltese cross moving sinusoidally around 2D of accommodative demand with 1D amplitude at 0.2 Hz. The amplitude and phase (delay) of the accommodation response were compared to the actual vergence of the stimulus to obtain gain and temporal phase, calculated from wavefront aberrations recorded over time during experimental trials. The tested conditions were as follows: Correction of all the subject's aberrations except defocus (C); Correction of all the subject's aberrations except defocus and habitual second‐order astigmatism (AS); Correction of all the subject's aberrations except defocus and odd higher‐order aberrations (HOAs); Correction of all the subject's aberrations except defocus and even HOAs (E); Natural aberrations of the subject's eye, i.e., the adaptive‐optics system only corrected the optical system's aberrations (N); Correction of all the subject's aberrations except defocus and fourth‐order spherical aberration (SA). The correction was performed at 20 Hz and each condition was repeated six times in randomised order.ResultsAverage gain (±2 standard errors of the mean) varied little across conditions; between 0.55 ± 0.06 (SA), and 0.62 ± 0.06 (AS). Average phase (±2 standard errors of the mean) also varied little; between 0.41 ± 0.02 s (E), and 0.47 ± 0.02 s (O). After Bonferroni correction, no statistically significant differences in gain or phase were found in the presence of specific monochromatic aberrations or in their absence.ConclusionsThese results show that the eye's monochromatic aberrations are not necessary for accommodation to track dynamic accommodative stimuli.

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The role of optical defocus in regulating refractive development in infant monkeys

Cited by 337 publications

References 48 publications

Ciliary body thickness in unilateral high axial myopia

Ciliary body thickness in unilateral high axial myopia

Visual regulation of refractive development: insights from animal studies

Human eyes do not need monochromatic aberrations for dynamic accommodation

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