Peripheral Eye Length Evaluation in Myopic Children Undergoing Orthokeratology Treatment for 12 Months Using MRI.

Purpose: To investigate changes in peripheral eye length (PEL) in myopic children undergoing orthokeratology (Ortho-K) treatment for 12 months using MRI. The results were compared to single vision spectacle wearers (SVS). Patients and Methods: A total of 70 children with myopia (aged 8-9 years old) were recruited. A total of 45 children were fitted with Ortho-K, and 25 were fitted with SVS. The PEL and axial length (AL) were measured by using MRI 3-Tesla, whereas central and peripheral refraction (PR) measurements were conducted at ±30 degrees horizontally with nasal (N) and temporal (T) intervals of 10°, 20°, and 30° and with an open field autorefractometer (WAM-5500 Grand Seiko). All the measurements were conducted at the baseline and 12 months. Results: The MRI analysis indicates that at 12 months, the SVS group showed more elongation of the PEL and AL at all eccentricities than the Ortho-K group did (p < 0.05). The Ortho-K group only showed significant PEL elongation beyond 20 degrees at N20, N30, T20, and T30 (p < 0.05); however, a significant reduction in the AL was detected in the center AL, N10, and T10 (p < 0.05). All eccentricities in the relative PR of the Ortho-K group were significantly more myopic than at the baseline (p < 0.05), whereas in the SVS group, all eccentricities in the relative PR were shown to be significantly more hyperopic than at the baseline (p < 0.05). The PEL and PR showed negative correlations at 12 months in the Ortho-K group. Conclusion: MRI analysis can be utilized to describe changes in PEL in myopic children. It appears that as myopia progressed in Ortho-K lens wearers, the PEL increased by a greater amount than the AL did; thus, the retina was reshaped to become increasingly oblate and to display peripheral myopic defocus.

Comparison of vision-related quality of life between wearing Orthokeratology lenses and spectacles in myopic children living in Kuala Lumpur.

PURPOSE: There are limited reports available on the impact of wearing Orthokeratology (ortho-K) lenses on the quality of life of Asian children. This study evaluated and compared vision-related quality of life (VRQoL) between myopic children wearing ortho-K lenses and single-vision spectacles (SVSs), living in Kuala Lumpur, using Paediatric Refractive Error Profile (PREP) questionnaires. METHODS: This is a cross sectional study. Myopic children who had been wearing ortho-K and SVSs for 12 months were recruited, and the questionnaires were distributed online. The PREP scores were obtained using a summary scoring method. The Shapiro-Wilk test was used to determine data normality. Unpaired t-test was performed for normally distributed data, and the Mann-Whitney test for non-normally distributed data. P < 0.05 was considered significant. RESULTS: A total of 70 subjects participated in this study (45 ortho-K and 25 SVSs), with a mean age of 10.86 ± 0.73 years. The mean scores for all the items were higher in ortho-K than SVS wearers (p < 0.05). With regard to symptoms during ortho-K lens wear at night, <10 % of the subjects reported difficulty falling asleep, itch/burning/dry eyes and foreign body sensation after lens insertion. CONCLUSION: Ortho-K improves the vision-related quality of life of myopic school children in Kuala Lumpur. Thus, it should be considered by more local optometrists when managing myopic children.

Corneal endothelial morphology of healthy myopic Malaysian children of Chinese ethnicity aged 8-9 years and its association with axial length.

Background: This is a cross-sectional study to further understand the effects of axial length elongation on the corneal endothelial cell's morphology in myopic children. Abnormal changes in the morphology of corneal endothelium are indicators of corneal stress or instability which could be linked to myopia. Methods: 111 school children comprising of 37 emmetropes, 37 mild myopes and 37 moderate myopes aged 8-9 years old were recruited. Visual acuity was measured using the LogMar chart, cycloplegic refraction was determined using an open-field autorefractor (Grand Seiko WAM-5100, Hiroshima, Japan) and refined using subjective refraction. Morphology of corneal endothelial cells [endothelial cell density, coefficient of variation, hexagonality and central corneal thickness] was evaluated using a non-contact specular microscope (Topcon SP-2000P). Axial length was measured with A-scan ultrasound biometry (PacScan Plus, Sonomed Escalon, NY). The correlation between morphology of corneal endothelial cells and axial length were assessed using Pearson Correlation and Linear regression analysis. Results: There was no significant difference in corneal endothelial cells and axial length between gender (p>0.05). Significant reduction in endothelial cells density and hexagonality and increased coefficient of variation was found in eyes of higher myopic power which had longer axial when compared to emmetropes (p<0.001). Except for central corneal thickness, all corneal endothelial cells parameters correlated significantly with axial length (p<0.05). For every 1mm increase in axial length, endothelial cells density decreased by 73.27cells/mm 2, hexagonality decreased by 2.32% and coefficient of variation increased by 1.75%. Conclusions: There were significant changes in morphology of cornea endothelial cells in young moderate myopic children of Chinese ethnicity at 8-9 years of age. This result provides normative data for Malaysian children of Chinese ethnicity that can be used for comparison and reference for clinical procedures, thereby facilitating decision-making with respect to interventions for myopia control, especially in prescribing contact lens for children.

Ocular Dimensions, Refractive Error, and Body Stature in Young Chinese Children with Myopia in Kuala Lumpur, Malaysia.

Purpose: Eyeball shape varies with refraction and body stature. Nevertheless, there are few reports on three-dimensional measurements of eyeball shape in children. The aim of this cross-sectional observational study was to investigate the associations between three-dimensional measurements of ocular dimensions, refractive error, and body stature in young Chinese children with myopia in Kuala Lumpur. Materials and Methods: Thirty-five female and 35 male school children aged 8-9 years old were recruited in this study. Cycloplegic spherical equivalent (SE) and visual acuity (VA) were determined using a logarithm of the minimum angle of resolution (logMAR) chart. Body mass index (BMI), body height, and head circumference were ascertained. Three ocular dimensions, that is, longitudinal axial length (LAL), horizontal width (HW), and vertical height (VH), were determined using magnetic resonance imaging (MRI). Results: There were significant differences among the ocular dimensions in the myopic children. Bonferroni-corrected pairwise t-tests showed that LAL was significantly longer (mean difference, 0.318 mm) than VH, which was in turn significantly longer (mean difference, 0.245 mm) than HW. Body height was significantly correlated with LAL (p < 0.001) and SE (p < 0.001), and multivariate linear regression confirmed that longer LAL and more myopic SE were associated with increased body height (p < 0.001 for both) but not BMI (p = 0.894 and p = 0.413) or head circumference (p = 0.305 and p = 0.226). Conclusion: This study confirms previous reports that changes in ocular dimensions are associated with body height in young children. Axial elongation (forming a prolate profile) occurs in myopic children of both genders at a young age.