眼内レンズによるモノビジョン法における近見時の両眼加算の検討

Binocular summation during near gaze in pseudophakic monovision

要約　目的：単焦点眼内レンズを用いたモノビジョン法の近見時の両眼加算を検討。対象と方法：術後6か月以上経過し，遠方両眼開放視力1.0以上の180例（男性56例，女性124例；平均年齢70±8歳）である。近見時の両眼加算を，近方視力が単眼視より両眼視時で一段階以上上昇したものと定義し，両眼加算あり群64例と両眼加算なし群116例で，術後屈折値・近見外斜位角度・近方瞳孔径・縮瞳率を比較した。結果：両眼加算あり群では非優位眼の術後屈折値－1.48±0.78D，近方瞳孔径2.51±0.46mm，両眼加算なし群ではそれぞれ－1.87±0.79D，2.70±0.43mmで両群間に有意差があり（p＜0.05），近見外斜位角度と縮瞳率は有意差はなかった。結論：非優位眼の屈折値が－1.50D，近方瞳孔径が2.5mm程度で近見時の両眼加算が得やすかった。

Abstract.　Purpose：To report binocular summation during near gaze by persons implanted with monofocal intraocular lens（IOL）. Cases and Method：This prospective study was made on 180 persons who were implanted with monofocal IOL 6 months before. The series comprised 56 males and 124 females. The age averaged 70 years. Binocular summation was defined as positive when near visual acuity was better during binocular gaze than with one eye only. Results：Binocular summation was positive in 64 cases and negative in 116 cases. Postoperative refraction of nondominant eye was －1.48±0.78D in cases with dominant binocular summation and －1.87±0.79D in cases without. The difference was significant（p＜0.05）. Pupil diameter during near gaze was 2.51±0.46 mm and 2.70±0.43 mm respectively. The difference was significant（p＜0.05）. There was no difference in the angle of exophoria during near gaze or rate of miosis between the two groups. Conclusion：Binocular summation tended to be positive when the refraction of nondominant eye was －1.50D or pupil diameter during near gaze was 2.5 mm.