アイドラ®を用いたMRD-1の測定

Measuring margin reflex distance-1 using Idra®

要約　目的：アイドラ^®（Idra^®）は，ドライアイに対する検査機器で，開瞼時の瞳孔中央から上眼瞼縁までの距離（MRD-1）も測定することが可能である。眼瞼下垂の手術前後のMRD-1値について，従来のメジャーを用いた測定値とアイドラを用いた測定値の相関を調査した。また，アイドラで1回のみ測定した場合と3回測定し中央値を採用した場合を比較した。

対象と方法：2024年11月〜2025年1月に，横浜桜木町眼科で挙筋前転法を施行し，術前，術後1週間の時点でメジャーおよびアイドラを用いてMRD-1を測定した症例を対象とした。診療録からアイドラで1回測定した群（アイドラ1回測定群）と3回測定し中央値を採用した群（アイドラ3回測定群）で，それぞれメジャーでの測定値と比較した。

結果：アイドラで1回のみ測定した症例は66名116眼，3回測定し中央値を採用した症例は50名91眼であった。術前のMRD-1は，アイドラ1回測定群では，メジャー測定値は1.1±1.1mm，アイドラ測定値は1.4±1.3mm，相関係数は0.79で，アイドラ3回測定群では，メジャー測定値は1.2±1.0mm，アイドラ測定値は1.5±1.1mm，相関係数は0.86で，それぞれ有意差があった（p＜0.01）。術後のMRD-1は，1回測定群では，メジャー測定値は3.3±0.8mm，アイドラ測定値は3.0±1.0mm，相関係数は0.80で，3回測定群では，メジャー測定値は3.5±0.9mm，アイドラ測定値は3.4±1.0mm，相関係数は0.90で，それぞれ有意差があった（p＜0.01，p＝0.03）。

結論：アイドラを用いたMRD-1測定は，従来のメジャーでの測定との相関が強く，3回測定し中央値を採用することで，相関がさらに強くなる。術前はメジャーでの測定値のほうがアイドラ測定値より有意に弱く，術後はメジャーでの測定値のほうがアイドラ測定値より有意に高い。本測定法は赤外線撮影でまぶしさがなく，測定と解析が簡便かつ迅速であり，測定単位が0.1mmと精密な数値化が可能であり，従来の測定より正確である可能性も考えられる。

Abstract　Purpose：Idra^® is a diagnostic device for dry eye that can be used to measure the margin reflex distance-1（MRD-1）. MRD-1 is the distance from the pupillary center to the upper eyelid margin in the open-eye position. We examined the correlation between the MRD-1 obtained with Idra^® and that obtained with conventional ruler-based measurement before and after ptosis surgery. We also compared the MRD-1 from a single Idra^® measurement with the median of three measurements.

Participants and Methods：Patients who underwent levator advancement between November 2024 and January 2025 were included. The MRD-1 was measured using a ruler and the Idra^® prior to and at one week after surgery. The data were compared（between ruler-based and Idra^® measurements based on medical records；the measurements were obtained once or calculated as the median of three trials.

Results：A total of 66 patients（116 eyes） and 50 patients（91 eyes） were included in the single- and three-measurement groups, respectively. The preoperative MRD-1 ruler and Idra^® values were 1.1±1.1 and 1.4±1.3 mm in the single-measurement group, respectively, with a correlation coefficient of 0.79. The preoperative ruler and Idra^® values were 1.2±1.0 and 1.5±1.1 mm in the three-measurement group, respectively, with a correlation coefficient of 0.86. Significant difference was observed in each case（p＜0.01） The postoperative MRD-1 ruler and Idra^® values in the single-measurement group were 3.3±0.8 and 3.0±1.0 mm, respectively, with a correlation coefficient of 0.80. The postoperative ruler and Idra^® values in the three-measurement group were 3.5±0.9 and 3.4±1.0 mm respectively, with a correlation coefficient of 0.90. Also significant difference was observed in each case（p＜0.01, p＝0.03）

Conclusion：The Idra^®-measured MRD-1 strongly correlated with the conventional ruler-based measurements, and the correlation further strengthened for the median of three measurements. Before surgery the ruler-based measurements were significantly lower than Idra^®-measured MRD-1, after surgery the rular-based measurements were significantly higher than Idra^®-measured MRD-1. Idra^® uses infrared imaging, avoids glare, enables rapid and simple measurement and analysis, and provides precise quantification in 0.1 mm units. Idra^® may more accurately measure MRD-1 than conventional methods.