白内障摘出術による眼球光学系の変化

Changes in the optical system following cataract surgery

　合併症を認めなかった67人83眼の白内障手術前後の屈折要素の変化，とくに眼軸長の変化を検討し，以下の結果を得た．

（1）術前眼軸長が23.50mm以下の群（43眼）では，術前眼軸長と術後の眼軸長変化に相関を認めなかった（r＝−0.04,p＞0.05）．術前眼軸長が23.50mmを超える群（40眼）では，術前眼軸長と術後の眼軸長短縮に有意の相関を認めた（r＝0.50,p＜0.005）．

（2）術後の眼軸長変化は白内障のタイプには無関係で，手術法（嚢内法，嚢外法）による差も認めなかった（p＞0.05）．

（3）術前前房深度，水晶体厚および手術による角膜屈折力の変化は術後の眼軸長変化と相関を示さなかった（p＞0.05）．

（4）術後1カ月目とそれ以降（平均9カ月目）の眼軸長を49眼において検討した結果，両群間に有意差を認めず，このことから合併症のない白内障術後において眼軸長はほぼ1カ月で安定化するものと考えられた．

（5）以上の結果より，とくに近視眼における人工水晶体度数決定に際しては，水晶体摘出による眼軸長短縮を考慮する必要があると考えられた．

Quantitation of refractive elements, including the axial length, was performed in 83 eyes before and one month after surgery. The cases averaged 67 years in age. The removal of the lens was done in-tracapsularly in 63 eyes and extracapsularly in 20 eyes.

In 43 eyes which measured less than 23.5mm in axial length before surgery, the changes in axial length induced by surgery occurred in a rando-mized fashion. In 40 eyes which measured more than 23.5mm in axial length before surgery, there was a positive correlation between the presurgical axial length and the decrease in axial length induced by surgery. No difference was noted in the induced changes in axial length between intra- and extra-capsular extraction. The induced changes in the axial length were independent of other refractive elements or the type of cataract.

The axial length was determined again in 49 eyes after 3 months or more (average : 9 months) follow-ing surgery. The values were identical with those measured 1 month after surgery. The findings suggest that a possible decrease in the axial length following cataract surgery should be considered while deciding the power of intra-ocular lens in myopic eyes.