AIM: To observe the effect of eccentricity of the optical treatment zone on retinal defocus after wearing orthokeratology lens for 12mo.
METHODS: In this case-control study, a total of 120 myopic patients(120 eyes)who completed the fitting in our hospital from March 2021 to September 2021 and insisted on wearing orthokeratology lenses for 12mo were selected. According to the eccentricity after wearing lenses for 12mo, they were divided into the low eccentricity group(<0.5mm, 58 cases, 58 eyes)and the moderate and high eccentricity group(≥0.5mm, 62 cases, 62 eyes). The optical treatment zone diameter(OTZD), eccentricity, axial length(AL), pupil diameter(PD)and refraction difference value(RDV)were evaluated after 12mo of wearing orthokeratology lenses, and the correlation between RDV and eccentricity was analyzed.
RESULTS: After wearing orthokeratology lenses for 12mo, AL growth and RDV at 30°～40° and 40°～53° from the fovea were significantly lower in the moderate and high eccentricity group than in the low eccentricity group(all P<0.05). In all patients, RDV at 40°～53° from the fovea was positively correlated with AL growth and OTZD(rs=0.544, 0.333, both P<0.01), and negatively correlated with eccentricity(rs=-0.224, P=0.014).
CONCLUSION: Peripheral retinal defocus is related to eccentricity and OTZD after wearing orthokeratology lenses. The greater eccentricity and the smaller OTZD within a certain range can induce more peripheral retinal myopic defocus, leading to a better control of AL growth.