시력에 영향을 줄 수 있는 안과적 질병이나 질환을 가지고 있는 자, 원추각막, 안과적 수술을 받은 자, 콘택트렌즈 착용자는 제외하였다.
Those who had ophthalmic diseases or diseases that could affect vision, those who had conical cornea, ophthalmic surgery, and those who had contact lenses were excluded.