Anisomyopia and orthokeratology for myopia control - Axial elongation and relative peripheral refraction.

PURPOSE: To investigate axial elongation (AE) and changes in relative peripheral refraction (RPR) in anisomyopic children undergoing orthokeratology (ortho-k). METHODS: Bilateral anisomyopic children, 7-12 years of age, were treated with ortho-k. Axial length (AL) and RPR, from 30° nasal (N30°) to 30° temporal (T30°), were measured at baseline and every 6 months over the study period. AE, changes in RPR and changes in the interocular AL difference were determined over time. RESULTS: Twenty-six of the 33 subjects completed the 2-year study. The AE of the higher myopic (HM) eyes (at least 1.50 D more myopia than the other eye) (0.26 ± 0.29 mm) was significantly smaller than for the less myopic (LM) eyes (0.50 ± 0.27 mm; p = 0.003), leading to a reduction in the interocular difference in AL (p = 0.001). Baseline RPR measurements in the HM eyes were relatively more hyperopic at T30°, N20° and N30° (p ≤ 0.02) and greater myopic shifts were observed at T20° (p < 0.001), T30° (p < 0.001), N20° (p = 0.02) and N30° (p = 0.01) after lens wear. After 2 years of ortho-k lens wear, temporal-nasal asymmetry increased significantly, being more myopic at the temporal locations in both eyes (p < 0.001), while AE was associated with the change in RPR at N20° (ß = 0.134, p = 0.01). The interocular difference in AE was also positively associated with the interocular difference in RPR change at N30° (ß = 0.111, p = 0.02). CONCLUSIONS: Ortho-k slowed AE in bilateral anisomyopia, with slower growth in the HM eyes leading to a reduction in interocular AL differences. After ortho-k, RPR changed from hyperopia to myopia, with greater changes induced in the HM eyes, and slower AE was associated with a more myopic shift in RPR, especially in the nasal field of both eyes.

[The Influence of Short-term Orthokeratology on Tear Film in Adult Myope].

OBJECTIVE: To study the changes of tear film after short-term overnight orthokeratology wearing in adult myope. METHODS: Fifty adult myope aged 18 to 38 years old were enrolled in this study. The patients wore orthokeratology 6-10 h every night during this study. Data such as non-invasive tear break-up time (NITBUT), fluorescent tear break-up time (FTBUT), lower tear meniscus height (LTMH), corneal fluorescent staining as well as ocular surface disease index (OSDI) questionnaire score were measured at baseline, 1 d, 7 d, 14 d, 30 d and 90 d. RESULTS: Forty-four subjects completed the follow-up study. Tear break-up time (TBUT) decreased and became stable at 14 d after overnight orthokeratology wearing. LTMH sustained decreased and there was a difference after 90 d overnight wearing （ P<0.05）. Compared with baseline, the grade of corneal staining increased at all time points （ P<0.05）. As for the OSDI score, there was no difference at all time points. CONCLUSION: After overnight orthokeratology wearing, tear film stability and tear secretion decreased. Adult myope seems easily to suffer corneal injury after overnight orthokeratology wearing.