試作したプラスチック非球面白内障レンズについて

New Aspheric Cataract Lens of Optical Plastics

緒言

　眼鏡レンズを理想に近づける一つの条件を示すTscherning楕円から明らかなように，遠用レンズの場合，＋8Dをこえる強度凸レンズでは球面レンズを以てしては非点収差を除くことが不可能で，非球面が必要となる。先に第1報^1），第2報^2）において，非点収差を除去した光学ガラス製の楕面レンズの矯正眼鏡を装用させた時の無水晶体眼の視機能を球面レンズ，双曲面レンズ装用時のそれと比較検討し，光学的な特性が視機能に反映された結果を得たが，今回さらに光学プラスチックCR39を材料とした軽量の楕円面白内障レンズの遠用ならびに近用眼鏡を無水晶体症例に使用させたので，ここに報告する。

A new cataract lens with an ellipsoidal sur-face elliminating the oblique astigmatism was made from optical plastics.The correcting spec-tacles with such lenses for distance and reading were fitted for 4 aphakic patients. The extentof visual field, the visual acuity at oblique gaze and the distortion of space perception experi-enced often by cataract lens wearers were tested, and the aspheric cataract lens gave the better results than the spherical or toric one in all cases.

The plastic cataract lens has half the weight when compared with the lens of glass materials. The comfortable wear of the former lenses mentioned by the patients was considered to be resulted therefrom as well as from the optical properties. Furthermore, the light-weight specta-cles were easily weared in the correct position not to be slipped down. Finally the remarks on the spectacle perscription for aphakia, especially the importance of the vertex distance, were discussed.