3焦点眼内レンズ挿入眼における角膜乱視の影響

Effect of corneal astigmatism in eyes with trifocal intraocular lens

要約　目的：3焦点眼内レンズ（IOL）が挿入された症例において，軽度乱視が術後視機能に及ぼす影響を後ろ向きに検討した。

対象と方法：2017年5月〜2021年3月に東京歯科大学水道橋病院にて白内障手術が施行され，トーリック機能のない3焦点IOLが挿入された症例のうち，オートケラトメータで術前の角膜前面乱視が1.0D未満の症例を対象とした。診療記録から術前角膜乱視，挿入IOL度数，術後1か月以降の遠方，40cm，30cmの裸眼視力を調べた。さらに，術前の角膜乱視を0.5D未満と0.5D以上1.0D未満の2群に分け，各距離の術後裸眼視力を比較した。

結果：症例は100例172眼，平均年齢は66.0±9.3歳，男性33例，女性67例，直乱視87眼，倒乱視40眼，斜乱視45眼であった。乱視軸ごとの度数と術後裸眼視力の相関では，倒乱視群のみ度数が増えると遠方と40cmで視力低下の傾向であった。また，乱視度数0.5D未満と0.5D以上1.0D未満の2群間で平均裸眼視力を比較したところ，倒乱視群のみ全距離において0.5D以上1.0D未満群が0.5D未満群より有意に低下していた。

結論：倒乱視例では3焦点IOL挿入後，術前角膜乱視が軽度でも視力低下が認められ，低加入度トーリックモデルの有用性が示唆された。

Abstract　Purpose：To retrospectively investigated the effect of mild astigmatism on postoperative visual function in patients with trifocal intraocular lenses（IOLs）.

Subjects and Methods：Patients who underwent cataract surgery with a trifocal IOL without toric function（TFNT00, Alcon）between May 2017 and March 2021 at Tokyo Dental Collage Suidobashi Hospital, and had preoperative anterior corneal astigmatism of less than 1.0D were included. Preoperative corneal astigmatism, IOL power, and uncorrected visual acuity（UCVA）at distance, 40 cm and 30 cm 1 month postoperatively were obtained from the medical records. Preoperative astigmatisms of with-the-rule（WTR）, against-the-rule（ATR）and oblique astigmatism were divided into two groups（＜0.50D and between 0.5D and 1.00D）, and their influence on UCVA at all distances were evaluated.

Results：There were 172 eyes of 100 cases（33 males and 37 females）included, with a mean age 66.0±9.3 years Eighty-seven eyes had WTR, 40 eyes ATR, and 45 eyes oblique astigmatism. The correlation between the amount of astigmatism and postoperative UCVA at all distances were not found in the WTR and oblique groups. However, the ATR group showed a correlation at distance and 40 cm. UCVA of the 0.5-1.0D group was significantly lower than that of the＜0.5D group at all distances in the ATR group（distance p＝0.004, 30 cm p＝0.048, 40 cm p＝0.020）.

Conclusion：In cases of ATR, mild preoperative corneal astigmatism between 0.5D and 1.0D affects postoperative UCVA, and trifocal IOL with a low amount of cylinder correction is suggested to be useful in these cases.