Morphological Correlations of Clinical Lens Changes: Non-opaque Lens Defects

To review the published evidence to evaluate the ability of orthokeratology (Ortho-K) treatment to reduce myopic progression in children and adolescents compared with the use of spectacles or daytime contact lenses for standard refractive correction.Literature searches of the PubMed database, the Cochrane Library, and the databases of clinical trials were last conducted on August 21, 2018, with no date restrictions but limited to articles published in English. These searches yielded 162 citations, of which 13 were deemed clinically relevant for full-text review and inclusion in this assessment. The panel methodologist then assigned a level of evidence rating to the selected studies.The 13 articles selected for inclusion include 3 prospective, randomized clinical trials; 7 nonrandomized, prospective comparative studies; and 3 retrospective case series. One study provided level I evidence, 11 studies provided level II evidence, and 1 study provided level III evidence. Most studies were performed in populations of Asian ethnicity. Change in axial length was the primary outcome for 10 of 13 studies and change in refraction was the primary outcome for 3 of 13 studies. In these studies, Ortho-K typically reduced axial elongation by approximately 50% over a 2-year study period. This corresponds to average axial length change values of approximately 0.3 mm for Ortho-K patients compared with 0.6 mm for control patients, which corresponds to a typical difference in refraction of approximately 0.5 diopters (D). Younger age groups and individuals with larger than average pupil size may have a greater effect with Ortho-K. Rebound can occur after discontinuation or change to alternative refractive treatment.Orthokeratology may be effective in slowing myopic progression for children and adolescents, with a potentially greater effect when initiated at an early age (6–8 years). Safety remains a concern because of the risk of potentially blinding microbial keratitis from contact lens wear.