個別A定数を用いた白内障術後屈折誤差の検討

Investigation of refractive error after cataract surgery using individual A constant

要約　目的：白内障手術にて個別A定数を用いて眼内レンズ（IOL）度数計算を行い，術後屈折誤差につき検討した報告。対象と方法：対象は過去1年間に白内障手術を施行した77例134眼。それ以前の2年間の白内障手術で得られたA定数（118.59）（PAC群）と個別A定数（IAC群）を用い，同じIOL度数における予測屈折値をSRK/T式で算出。術後1か月での自覚屈折値と比較した。結果：術後1か月での屈折誤差平均値（絶対値平均値）はPAC群が0.28±0.42D（0.42±0.29D），IAC群は0.08±0.41D（0.31±0.28D）で両平均値ともにIAC群が有意に小さかった（t検定，p＜0.001）。術後屈折誤差が各度数以内に入った症例割合は±0.25D以内の群のみIAC群が有意に多かった（χ²検定，p＜0.001）。結論：個別A定数で算出した予測屈折値のほうが術後屈折誤差は小さくなることが判明した。

Abstract.　Purpose：To report investigation of refractive error after cataract surgery using individual A constant in intraocular lens（IOL）. Cases and Method：This study was made on 134 eyes of 77 cases that received cataract surgery in the past one year. Power of IOL was calculated using the SRK/T formula. Prospective refraction in each IOL were calculated using personal A constant（PAC group）and individual A constant（IAC group）provided by cataract surgery during 2-3 years ago. Both groups were evaluated regarding subjective refraction in one month after surgery. Results：The means of refractive error（absolute refractive error）in one month later after surgery were 0.28±0.42D（0.42±0.29D）（PAC group）, 0.08±0.41D（0.31±0.28D）（IAC group）. Both means were significant difference between the two groups（t-test, p＜0.001）. In ratio of refractive error within each diopter, the error group within ±0.25D was significant difference（χ² test, p＜0.01）. Conclusion：It became that the refractive error after cataract surgery using individual A constant was significantly less compared with the usual method. It was suggested that this calculation method reduced the refractive error after cataract surgery.