Changes in Shape Discrimination Sensitivity Under Glare Conditions After Orthokeratology in Myopic Children: A Prospective Study

PURPOSE. To investigate changes in shape discrimination under mesopic conditions with and without glare after orthokeratology in myopic children. METHODS. This prospective study included 79 eyes of 79 myopic children (ages: 8- 16 years). Shape discrimination thresholds (SDTs) were measured using radial frequency patterns, with a radial frequency of 4 cycles/360 & DEG;, a peak spatial frequency of 3 cycles per degree, a contrast of 20%, and a mean radius of 1.5 degrees. SDT under mesopic conditions with and without glare was measured before orthokeratology and again at 1 week and 1 month after orthokeratology. Changes in the SDTs and their relationships to baseline ocular parameters were analyzed. RESULTS. SDTs with glare decreased significantly at 1 week (-0.08 & PLUSMN; 0.15 log(arcsec), P < 0.001) and 1 month (-0.09 & PLUSMN; 0.15 log(arcsec), P < 0.001) after orthokeratology. SDTs without glare remained stable (P = 0.81 and P = 1.00, respectively). The difference between SDTs with and without glare also decreased significantly at 1 week (-0.10 & PLUSMN; 0.17 log(arcsec), P < 0.001) and at 1 month (-0.08 & PLUSMN; 0.18 log(arcsec), P = 0.001) after orthokeratology. Based on a multivariate analysis, the greater decrease in SDT with glare after 1 month of orthokeratology was associated with a higher baseline spherical equivalent refraction. CONCLUSIONS. Orthokeratology resulted in improved shape discrimination in myopic children under mesopic conditions but only when measured in the presence of glare.