Influence of Overnight Orthokeratology Lens Treatment Zone Decentration on Myopia Progression

Purpose. To investigate the effect of OK lens treatment zone decentration on myopia control. Methods. We retrospectively selected 30 OK lens wearers who met the following conditions in our hospital from more than 1300 cases: wearing lens in both eyes and only one eye was off-center while the other one was centric for more than 12 months. During the period of follow-up, the UCVA of each eye was better than 0.1 of logMAR and there were no obvious tropia, Kappa angle, and complications such as glare and diplopia. Result. Among 30 cases, 15 are males and 15 are females, with an average age of 9.3 +/- 1.51Y. There were no significant differences in equivalent spherical lens, astigmatism, e value, flat K, steep K, astigmatism, lens diameter, and toric between the two groups (p>0.05). The average distance of decentration was 0.73 +/- 0.25 mm. Axis growth per year in was 0.20 +/- 0.24 mm the OK-lens-decentered group and 0.29 +/- 0.20 mm in the OK-lens-centric group, which shows significant difference between them (p<0.05). According to the direction of decentration, 30 decentered eyes were divided into temporal group (20 eyes) and other direction group (10 eyes). The efficiency of myopia control (the growth of AL per year in OK-lens-decentered eye/the growth of AL per year in the contralateral OK-lens-centric eye) was 0.69 +/- 0.50 in the temporal decentration group and 0.75 +/- 0.52 in the other direction group, showing no significant difference between them (p>0.05). There was no significant correlation between the efficiency of myopia control and the degree of decentration among temporal decentration group (p>0.05). Conclusion. This self-control study without much interference factors shows that the decentration of OK lens can delay the development of myopia more effectively than being centric when uncorrected visual acuity was acceptable without obvious corneal complications, glare, or ghosting.