眼内レンズ挿入眼での光干渉眼軸測定（OA-1000TM）の精度の検討

Accuracy of axial length in pseudophakic eyes measured by coherence interferometry（OA-1000TM）

要約　目的：眼内レンズ挿入眼の眼軸長を光干渉測定法で計測した結果の報告。対象と方法：過去5か月間にアクリル製眼内レンズを挿入した84眼を対象とし，手術前と手術3か月後の眼軸長をOA-1000^TMで計測した。術前の信号対雑音比（signal to noise ratio：SNR）が6以上の45眼を高SNR群，6未満の39眼を低SNR群として両群を比較した。結果：術後の眼軸長は術前よりも全体で0.11mm短くなった。高SNR群では0.11mm，低SNR群では0.10mmであり，ばらつきが小さかった。術前後での眼軸長差と術後の屈折誤差には各群間に有意差がなかった。結論：眼内レンズ挿入後には眼軸長が短くなるが，術前の眼軸長の値は，挿入する眼内レンズの決定に信頼できる指標となる。

Abstract.　Purpose：To report the outcome of axial length measurement before and after insertion of intraocular lens（IOL）. Cases and Method：This study was made on 84 eyes that underwent cataract surgery with insertion of acrylic IOL during a 5-month period. Axial length was measured by coherence interferometer（OA-1000^TM）before and after cataract surgery. The eyes were assigned to two groups according to the signal-to-noise ratio（SNR）. Forty-five eyes were assigned to high-SNR group that showed 6 or higher SNR. The other 39 eyes were assigned to low-SNR group that showed less than 6 SNR. Results：The axial length became shorter by an average of 0.11 mm after surgery. The value averaged 0.11 mm in high-SNR and 0.10 mm in low-SNR group. There was no difference between the two groups regarding the change in axial length or refraction after surgery. Conclusion：Axial length of the eye decreases after surgery. Its value measured before surgery serves as a reliable guide in predicting the power of IOL to be inserted.