Eccentricity-dependent effects of simultaneous competing defocus on emmetropization in infant rhesus monkeys

Smith, Earl L.; Arumugam, Baskar; Hung, Li-Fang; She, Zhihui; Beach, Krista M.; Sankaridurg, Padmaja

doi:10.1016/j.visres.2020.08.003

Cited by 35 publications

(28 citation statements)

References 43 publications

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“…Currently all the existing theoretical hypotheses that the ortho-k lens controls myopia progression, such as the retinal peripheral defocus theory ( Gardner et al, 2015 ; Smith et al, 2020 ), the aberration theory ( Hiraoka et al, 2015 ; Zhang X. et al, 2020 ; Lau et al, 2020 ), and the accommodation theory ( Batres et al, 2020 ; Song et al, 2021 ), are based on the change of the corneal shape or reduction of the refractive error after ortho-k lens wear. The biomechanical interaction between the lens and the cornea or the entire eyeball is vitally important in the course of ortho-k treatment.…”

Section: Discussionmentioning

confidence: 99%

The Biomechanical Response of the Cornea in Orthokeratology

Fang

et al. 2021

Front. Bioeng. Biotechnol.

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Orthokeratology has been widely used to control myopia, but the mechanism is still unknown. To further investigate the underlying mechanism of corneal reshaping using orthokeratology lenses via the finite element method, numerical models with different corneal curvatures, corneal thicknesses, and myopia reduction degrees had been developed and validated to simulate the corneal response and quantify the changes in maximum stress in the central and peripheral corneal areas during orthokeratology. The influence of the factors on corneal response had been analyzed by using median quantile regression. A partial eta squared value in analysis of variance models was established to compare the effect size of these factors. The results showed central and peripheral corneal stress responses changed significantly with increased myopia reduction, corneal curvature, and corneal thickness. The target myopia reduction had the greatest effect on the central corneal stress value (partial eta square = 0.9382), followed by corneal curvature (partial eta square = 0.5650) and corneal thickness (partial eta square = 0.1975). The corneal curvature had the greatest effect on the peripheral corneal stress value (partial eta square = 0.5220), followed by myopia reduction (partial eta square = 0.2375) and corneal thickness (partial eta square = 0.1972). In summary, the biomechanical response of the cornea varies significantly with the change in corneal conditions and lens designs. Therefore, the orthokeratology lens design and the lens fitting process should be taken into consideration in clinical practice, especially for patients with high myopia and steep corneas.

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Section: Discussionmentioning

confidence: 99%

The Biomechanical Response of the Cornea in Orthokeratology

Fang

et al. 2021

Front. Bioeng. Biotechnol.

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“…Due to the presence of the two concentric defocus rings in the periphery, the rising edge of the inner ring may be closer to the center than that in MFCLs with only one defocus ring. Smith et al (2020) compared the treatment effects in infant monkeys with those in human clinical trials. They suggested that the relative effects on myopia control of the different optical treatments in both monkeys and humans were dependent on the eccentricity of the defocus.…”

Section: Discussionmentioning

confidence: 99%

“…However, more peripheral zones, beginning 3.25 mm from the lens center, had no effect ( Liu and Wildsoet, 2011 ). A study in monkeys reported that lenses imposing myopic defocus close to the optic axis were more effective in inhibiting axial growth than those in which defocus was limited to the more peripheral regions, e.g., 20 degrees away from the optic axis ( Smith et al, 2020 ).…”

Section: Introductionmentioning

confidence: 99%

The Spatial Distribution of Relative Corneal Refractive Power Shift and Axial Growth in Myopic Children: Orthokeratology Versus Multifocal Contact Lens

et al. 2021

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PurposeTo determine if the spatial distribution of the relative corneal refractive power shift (RCRPS) explains the retardation of axial length (AL) elongation after treatment by either orthokeratology (OK) or multifocal soft contact lenses (MFCLs).MethodsChildren (8–14 years) were enrolled in the OK (n = 35) or MFCL (n = 36) groups. RCRPS maps were derived by computing the difference between baseline and 12-month corneal topography maps and then subtracting the apex values. Values at the same radius were averaged to obtain the RCRPS profile, from which four parameters were extracted: (1) Half_x and (2) Half_y, i.e., the x- and y-coordinates where each profile first reached the half peak; (3) Sum4 and (4) Sum7, i.e., the summation of powers within a corneal area of 4- and 7-mm diameters. Correlations between AL elongation and these parameters were analyzed by multiple linear regression.ResultsAL elongation in the OK group was significantly smaller than that in the MFCL group (p = 0.040). Half_x and Half_y were also smaller in the OK group than the MFCL group (p < 0.001 each). Half_x was correlated with AL elongation in the OK group (p = 0.005), but not in the MFCL group (p = 0.600). In an analysis that combined eyes of both groups, Half_x was correlated with AL elongation (β = 0.161, p < 0.001).ConclusionsThe OK-induced AL elongation and associated RCRPS Half_x were smaller than for the MFCL. Contact lenses that induce RCRPS closer to the corneal center may exert better myopia control.

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“…It appears that the effect of the peripheral refraction on myopia inhibition depends on the retinal location, which should be relatively central [46]. A recent publication showed the highest effect in monkeys when the central unrestricted vision was small (1.5 • , 5.8 • , or 9.8 • , respectively) and the periphery was exposed to a simultaneous defocus (+3.00 D) [42,47]. The strength of the effect increased when the central unrestricted part of vision decreased in size.…”

Section: Peripheral Refraction and Image Qualitymentioning

confidence: 99%

Simultaneous Myopic Defocus for Myopia Control: Effect on Accommodation, Peripheral Refraction and Retinal Image Quality in Non-Presbyopic Patients

Fritschi¹,

Gerber²,

Eggler³

et al. 2021

Optics

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Exposing the retina to a simultaneous myopic defocus is an optical method that has shown a promising effect in slowing the progression of myopia. Optical treatments applying a simultaneous defocus are available in the form of soft contact lenses or multifocal lenses originally designed to correct presbyopia. Orthokeratology is another optical method that slows down the progression of myopia. With orthokeratology, it is hypothesized that a change in peripheral refraction could slow the progression of myopia. We aimed to measure the accommodation response between monofocal and multifocal contact lenses in young subjects. Additionally, we performed a ray-tracing simulation to visualize the quality of the retinal image and the refractive status in the retinal periphery. The accommodation and pupil size measurements were performed on 29 participants aged 24.03 ± 2.73 years with a refractive error (spherical equivalent) of −1.78 ± 1.06 D. With the multifocal lens in situ, our participants showed less accommodation in comparison to the monofocal contact lens (mean difference, 0.576 ± 0.36 D, p > 0.001) when focusing on a near target at 40 cm. Pupil size became smaller in both contact lens groups during an accommodation of 0.29 ± 0.69 mm, p ≤ 0.001 and 0.39 ± 0.46 mm, p ≤ 0.001 for monofocal and multifocal contact lenses, respectively. The ray-tracing model showed a degradation for central and peripheral vision with the multifocal contact lens. The peripheral refraction was relatively myopic in both contact lens conditions up to 30°. Even if the accommodation ability is without fault, parts of simultaneous myopic defocus are used for the near task. The peripheral refraction in the ray-tracing model was not different between the two contact lenses. This is contrary to the proposed hypothesis that myopic peripheral refraction slows down the progression of myopia in current optical methods.

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Eccentricity-dependent effects of simultaneous competing defocus on emmetropization in infant rhesus monkeys

Cited by 35 publications

References 43 publications

The Biomechanical Response of the Cornea in Orthokeratology

The Biomechanical Response of the Cornea in Orthokeratology

The Spatial Distribution of Relative Corneal Refractive Power Shift and Axial Growth in Myopic Children: Orthokeratology Versus Multifocal Contact Lens

Simultaneous Myopic Defocus for Myopia Control: Effect on Accommodation, Peripheral Refraction and Retinal Image Quality in Non-Presbyopic Patients

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