角膜周辺部のエキシマレーザー線状切開による家兎眼での乱視矯正効果

Correction of astigmatism in rabbits by linear incision of peripheral cornea with excimer laser

　角膜乱視の矯正を目的にエキシマレーザー（ArF，193nm）を用い，家兎角膜の12時方向，輪部より3mmと5�の位置に水平に線状切開を行い，角膜屈折力の変化を経時的に観察した。照射後，垂直方向の角膜屈折力は，2種類の切開とも遠視化を示したが，照射後1週目で5mmの切開のほうが平均0.88diopter（D）遠視化が強く認められた。水平方向の角膜屈折力は，3mmの切開では効果は不安定であったが，5mmの切開ではすべて近視化を示した。経時的には，垂直方向の遠視化は照射2週後にピークを示し，その後，徐々に減弱していったが，照射12週後でも3mmの切開で平均0.81D，5mmの切開で平均1.07Dの遠視化効果が得られた。

We incised the cornea with excimer laser in 11 rabbit eyes. The incision was placed horizontally in the superior corneal segment, was 6 mm long and 3 to 5 mm away from the limbus. We used an argon fluoride excimer laser with the wavelength of 193 nm and repetion rate of 100 Hz. The depth of the incision was two-thirds of the corneal thickness. The corneal curvature was measured up to 12 weeks after laser incision.

Flattening of the corneal along the perpendicularmeridian resulted after surgery. At one week after surgery, the amount of change in refraction was greater for incision 5 mm than 3 mm away from the limbus. Refractive changes along the horizontal meridian were variable after incision 3 mm away from the limbus. The changes were towards myopia in all the eyes after incision 5 mm away from the limbus. The induced changes in refraction along the vertical meridican reached a peak 2 weeks after surgery to decrease thereafter. At 12 weeks after surgery, the induced changes in refraction averaged 0.81 D for incisions 3 mm away from the limbus and 1.07 D for 5 mm from the limbus.