低SNR（signal-to-noise ratio）症例での光眼軸長測定（OA-1000TM）の精度

Accuracy of axial length in eyes with low signal-to-noise ratio measured by OA-1000TM

要約　目的：信号対雑音比が低い症例と眼内レンズ挿入眼の眼軸長を光干渉眼軸測定装置（OA-1000^TM）で測定した精度の評価。対象と方法：15か月間に眼内レンズを移植した395眼を対象とした。術前の信号対雑音比は，3未満が53眼，6未満が195眼，6以上が200眼であり，各群について術前後の眼軸長と術後屈折誤差を評価した。結果：術後の眼軸長は各群で約0.10mm低くなり，3群の間に有意差はなかった。自覚的な屈折誤差は全例で－0.32±0.55mmであり，3群の間に有意差はなかった。結論：信号対雑音比が低い眼でも高い精度の眼軸長の測定値が得られる。OA-1000^TMによる眼内レンズ挿入眼の眼軸長測定値は安定し，信頼できる。

Abstract.　Purpose：To report the accuracy of axial length in phakic and pseudophakic eyes with low signal-to-noise ratio measured by coherence interferometer（OA-1000^TM）. Cases and Method：This study was made on 395 eyes that received cataract surgery with implantation of intraocular lens（IOL）in the past 15 months. Signal-to-noise ratio before surgery was less than 3 in 53 eyes, less than 6 in 195 eyes and 6 or over in 200 eyes. Each group was evaluated regarding axial length before and after surgery and postoperative refractive error. Results：Axial length became shorter by about 0.10 mm in each group. There was no difference among the 3 groups. Subjective error in refraction averaged －0.32±0.55 mm in the 395 eyes. There was no difference among the 3 groups. Conclusion：Measurement OA-1000^TM gives reliable values of axial length in eyes with low signal-to-noise ratio including pseudophakic eyes.