Higher-Order Aberrations and Axial Elongation in Myopic Children Treated With Orthokeratology

Abstract

Citation: Lau JK, Vincent SJ, Cheung S-W, Cho P. Higher-order aberrations and axial elongation in myopic children treated with orthokeratology. Invest Ophthalmol Vis Sci. 2020;61(2):22. https://doi.org/10.1167/iovs. 61.2.22 PURPOSE. This retrospective longitudinal study aimed to examine the relationship between ocular higher-order aberrations (HOA) and axial eye growth in young myopic children undergoing orthokeratology (ortho-k) treatment. METHODS.Axial length and ocular HOA, measured under cycloplegia annually over a 2year period from the right eyes of myopic children, who previously completed ortho-k clinical trials, were retrieved. Linear mixed model analyses were applied to determine the association between ocular HOA, other known confounding variables (age, sex, and refractive error), and axial eye growth. RESULTS.Data from 103 subjects were analyzed. The root-mean square (RMS) values of total ocular HOA (third to sixth orders combined), spherical (Z 0 4 and Z 0 6 combined), and comatic (Z −1 3 , Z 1 3 , Z −1 5 , and Z 1 5 combined) aberrations increased by approximately 3, 9, and 2 times, respectively, after 2 years of ortho-k treatment. After adjusting for age, sex, and refractive error, higher RMS values of total HOA and spherical aberrations were associated with both longer axial length and slower axial elongation (all P < 0.01). For individual Zernike term coefficients, a higher level of positive spherical aberration (Z 0 4 ) was also associated with longer axial length and slower axial elongation (both P < 0.01), after adjusting for baseline HOA. CONCLUSIONS.Ortho-k for myopia control significantly increases the Zernike coefficients and therefore the RMS values for a range of total ocular HOA terms or metrics in children. These findings suggest the potential role of HOA, particularly spherical aberration, as the possible mechanism of slowing axial elongation in ortho-k treatment.

The human axial length and choroidal thickness responses to continuous and alternating episodes of myopic and hyperopic blur

“…In eyes experiencing chronic deprivation of form vision through ocular conditions such as ptosis [12,13], congenital cataract [14], corneal opacity [15], and vitreous haemorrhage [16], abnormal ocular growth is often observed. Similarly, manipulation of retinal image focus through optical treatment strategies such as bifocal or multifocal spectacles [17,18], soft multifocal contact lenses [19,20], or orthokeratology [21][22][23][24] have been linked with reduced progression of axial myopia in children. Investigations in human eyes have also shown a bi-directional response to short-term imposed continuous myopic and hyperopic defocus in children [25] and adults [26][27][28][29][30][31], with a small magnitude axial length reduction associated with rapid choroidal thickening in response to myopic defocus and axial elongation associated with rapid choroidal thinning in response to hyperopic defocus.…”

Higher order aberrations and axial elongation in combined 0.01% atropine with orthokeratology for myopia control

“…9,11 Some authors have also reported a strong association between more positive primary spherical aberration and slower eye growth in both spectacle-wearing children 8 and those treated with orthokeratology. 10 While a significant difference in spherical aberration was observed between the two treatment groups after six months (mean 0.54 µm more positive primary spherical aberration in the AOK group), the magnitude of change in spherical aberration was not associated with the extent of eye growth ( Table 4). With respect to analyses of HOA's and eye growth in children treated with orthokeratology, this is the first study to examine the change in the optics of the eye using the natural pupil diameters rather than a fixed pupil size.…”

“…6 Recent longitudinal studies have reported an association between axial elongation with inherent corneal 7 or total ocular HOA's in spectacle-wearing children, 8 as well as the change in total ocular HOA's in children treated with orthokeratology. [9][10][11] These studies have utilised fixed pupil diameters across all participants (4-6 mm) with higher levels of individual Zernike terms, such as primary spherical aberration or coma (or greater HO RMS), associated with less axial eye growth. However, the natural pupil size of individuals may be an important factor in the regulation of eye growth with myopia control interventions, given that greater treatment efficacy has been reported for orthokeratology in children with larger pupil diameters.…”

“…Recent longitudinal studies have reported an association between axial elongation with inherent corneal 7 or total ocular HOA’s in spectacle‐wearing children, 8 as well as the change in total ocular HOA’s in children treated with orthokeratology 9–11 . These studies have utilised fixed pupil diameters across all participants (4–6 mm) with higher levels of individual Zernike terms, such as primary spherical aberration or coma (or greater HO RMS), associated with less axial eye growth.…”

A strategically oriented conception of optical prevention of myopia onset and progression

“…В некоторых работах последних лет повышению СА и комы после ОК-коррекции отводят самостоятельную роль в тормозящем прогрессирование эффекте данного воздействия [79,80]. Но прежде всего повышенный уровень аберраций увеличивает глубину фокусной области, снижая нагрузку на аккомодацию за счет повышения псевдоаккомодации.…”