ABSTRACT
Objective To analyze the peripheral defocus of the retina in myopic children wearing orthokeratology lenses(OK lenses)using multispectral refraction topography(MRT).Methods A retrospective study was conducted.A total of 128 eyes of 128 myopic children(right eye)who got OK lenses in Ineye Hospital of Chengdu University of TCM from January to April 2021 were included.The steep keratometry(Ks),flat keratometry(Kf),eccentricity at the meridian of Ks and eccentricity at the meridian of Kf were measured by corneal topography before wearing OK lenses.The central corneal thickness before wearing OK lenses,baseline axial length(AL1)and axial length(AL2)after wearing OK lenses for 1 year were measured by optical biometer,and retinal defocus value(RDV)after wearing OK lenses for 1 year was meas-ured by MRT.According to the change in axial length(CAL)after wearing OK lenses for 1 year,subjects were divided into the SAL group(CAL≤0.3 mm)and LAL group(CAL＞0.3 mm).The peripheral RDV in the range of 0°-10°,＞10°-20°,＞20°-30°,＞30°-40°,and＞40°-53°(RDV0°-10°,RDV10°-20°,RDV20°-30°,RDV30°-40°,RDV40°-53°),av-erage RDV in the range of 0°-53°,and average RDVs in the superior,inferior,temporal and nasal quadrants(RDV-S,RDV-I,RDV-T and RDV-N)of both groups were compared after wearing OK lenses for 1 year.In addition,the effect of RDV in different peripheral retinal regions on AL growth was analyzed.Results After wearing OK lenses for 1 year,the peripheral RDV20°-30°,RDV30°-40°,RDV40°-53°,TRDV,RDV-I and RDV-T were higher in the LAL group than those in the SAL group(all P＜0.05).Correlation analysis showed that AL1 was negatively correlated with CAL(P＜0.05),whereas age,peripheral RDV0°-10°,RDV-S,RDV-N and other ocular biological parameters were not correlated with CAL(all P＞0.05).The peripheral RDV10°-20°,RDV20°-30°,RDV30°-40°,RDV40°-53°,TRDV,RDV-I and RDV-T were positively correlated with CAL(all P＜0.05).Conclusion Peripheral retinal defocus in the range of 10°-53° in myopic children is closely related to AL growth.The lower the RDV,the slower the AL growth.