Multicenter study of Orthokeratorogy for infancy using " Breath-O Correct"

INTERVENTION: contact lens CONDITION: myopia and myopic astigmatism PRIMARY OUTCOME: Safty: uncorrected visual acuity; Efficacy: Decrease of corneal endothelial cell density INCLUSION CRITERIA: Participant must meet all of the following conditions listed below; 1) Patient who is 6 years old to 16 years old (including 6 years old and 16 years old), at the time of the consent acquisition. 2) Patient with ‐1.00 to ‐4.00D myopia. 3) Patient with astigmatism (spherical power being less than 1/2 of cylindrical power, and less ‐0.75D). 4) Patient whom examiner is able to observe both eyes. 5) Patient who is able to attend the hospital during the research. 6) Patient whose parent is able to take care the RGP lenses. 7) Patient who is able to acquire a consent of his/her adult legal representative.