On average, subjects wearing ortho-k lenses had a slower increase in axial elongation by 43% compared with that of subjects wearing single-vision glasses. Younger children tended to have faster axial elongation and may benefit from early ortho-k treatment. (ClinicalTrials.gov number, NCT00962208.).

This retrospective longitudinal analysis aimed to investigate the association between ocular higher-order aberrations (HOAs) and axial eye growth in Hong Kong children. Measures of axial length and ocular HOAs under cycloplegia were obtained annually over a two-year period from 137 subjects aged 8.8 ± 1.4 years with mean spherical equivalent refraction of −2.04 ± 2.38 D. A significant negative association was observed between the RMS of total HOAs and axial eye growth (P = 0.03), after adjusting for other significant predictors of axial length including age, sex and refractive error. Similar negative associations with axial elongation were found for the RMS of spherical aberrations ( and combined) (P = 0.037). Another linear mixed model also showed that greater levels of vertical trefoil , primary spherical aberration and negative oblique trefoil were associated with slower axial elongation and longer axial length (all P < 0.05). These findings support the potential role of HOAs, image quality and a vision-dependent mechanism in childhood eye growth.

Citation: Cho P, Cheung S-W. Protective role of orthokeratology in reducing risk of rapid axial elongation: a reanalysis of data from the ROMIO and TO-SEE studies. Invest Ophthalmol Vis Sci. 2017;58:141158: -141658: . DOI: 10.1167 PURPOSE. To determine the relative risk of rapid progression and number needed to treat (NNT) in younger and older children using combined data from the retardation of myopia in orthokeratology (ROMIO) and toric orthokeratology-slowing eye elongation (TO-SEE) studies.METHODS. Data from 136 subjects of two studies, ROMIO and TO-SEE, were retrieved (72 orthokeratology [ortho-k]: 37 ROMIO, 35 TO-SEE; 64 control: 41 ROMIO, 23 TO-SEE) and the myopia control effect on younger (6-8 years) and older (9-12 years) subjects evaluated. The rate of axial elongation was classified as not rapid (axial elongation ¼ <0.36 mm/year) or rapid (axial elongation >0.36 mm/year). RESULTS.Cumulative frequency curves showed that the younger subjects in the control group had the greatest and most rapid axial elongation at the end of 24 months. In the younger subjects, ortho-k lens wear significantly reduced the risk of rapid progression by 88.8% (P ¼ 0.002). The 2-year NNT for the younger ortho-k subgroup was 1.8, suggesting that treating just two younger subjects with ortho-k would prevent one subject from experiencing rapid progression over a 2-year period of treatment. The 2-year NNT for the older ortho-k subgroup was 11.8, which was statistically insignificant (P ¼ 0.197).CONCLUSIONS. Orthokeratology significantly reduced risk of rapid progression in younger subjects. Treating just two 6-to 8-year-old subjects with ortho-k instead of single-vision spectacles could prevent one subject from developing rapidly progressing axial elongation during this critical 2-year period.

PURPOSE.To investigate the short-term effect of orthokeratology (ortho-k) lens wear on the anterior segment length for validating the use of axial length for monitoring myopic progression after ortho-k treatment.METHODS. Thirty-seven and 39 subjects (ages: 7-10 years) were randomly assigned to wear ortho-k and single-vision spectacles, respectively. Central corneal thickness (CCT), anterior chamber depth (ACD), crystalline lens thickness (LT), and anterior segment length (ASL: summation of CCT, ACD, and LT) were measured before and 6 months after the treatment under cycloplegia. Changes in these parameters were evaluated and compared between the two groups of subjects.RESULTS. There were no significant between-group differences in the baseline data (P > 0.37). After 6 months of lens wear, in the ortho-k group, CCT was significantly reduced by 0.009 6 0.009 mm (P < 0.001), whereas ACD and LT remained unchanged (P > 0.15). In the spectacle group, ACD was significantly increased by 0.01 6 0.03 mm (P ¼ 0.008), whereas CCT and LT remained unchanged (P > 0.06). In both groups of subjects, ASL did not appreciably change but axial length was significantly increased by 0.10 6 0.10 mm and 0.20 6 0.11 mm in the ortho-k and the spectacle groups, respectively (P < 0.001).CONCLUSIONS. Eyeball elongation occurred in children wearing both ortho-k and single-vision spectacles. Since ASL was not affected by ortho-k treatment, axial length measured reflects the true growth of the eyeball and is a valid parameter for monitoring myopic progression in ortho-k treated eyes. (ClinicalTrials.gov number, NCT00962208.) (Invest Ophthalmol Vis Sci.

Background:  Our aim was to compare the clinical performance of a biweekly (second generation) silicone hydrogel lens and a biweekly hydrogel lens worn for daily wear modality. Methods:  We used a double‐masked study, in which non‐presbyopic, asymptomatic and adapted soft lens wearers were recruited. Subjects wore a silicone hydrogel lens in one eye and a hydrogel lens in the other (lens types and eyes were randomly assigned) for one month. Lenses were replaced every two weeks. Contact lens fitting, pre‐lens tear film thinning time, vision, corneal integrity and lens deposits were assessed before and every fortnight after delivery of new lenses. A questionnaire was used to compare the subjective performance of the two lens types. Results:  Thirty of the 33 subjects completed the study. There were no significant differences in lens fitting (centration and movement), pre‐lens tear film thinning time, vision or corneal integrity between the two lens types. Statistically, there was no significant difference in lens deposits between the two lens types but silicone hydrogel lenses tended to have more Grade 3 to 4 lipid deposits than hydrogel lenses. Subjects found no significant differences between the two lens types in terms of vision and comfort. Preference for silicone hydrogel lenses increased from 33 at the first after‐care visit to 50 per cent at the second after‐care visit. Conclusion:  This short‐term study demonstrates that the performance of silicone hydrogel and hydrogel lenses is comparable but the former tends to build up more lipid deposits than the latter. We did not find better performance in terms of ocular integrity of silicone hydrogel lenses compared to the hydrogel lenses, probably because the subjects were adapted asymptomatic contact lens wearers before commencing the study. Contact lens wearers having hypoxia‐related problems are likely to benefit from using silicone hydrogel lenses, as these lenses provide at least three times more oxygen than conventional hydrogel lenses.