照射径5mmと6mmでのエキシマレーザー屈折矯正手術

Excimer laser photorefractive surgery with ablation zone of 5 or 6 millimeters

　60以下の中等度近視を対象として，Summit社製エキシマレーザーを用いて照射径5mmと6mmで屈折矯正手術を施行し，両群の術後成績について比較検討した。術前屈折値を揃えた5mm群45眼，6mm群45眼において，調節麻痺下の屈折値は，5mm群では術後1,3,6か月ともに6mm群より有意に遠視化がみられた（p＜0.0001〜p＜0.01）。また，術後屈折値のばらつきも，すべての時点で6mm群は5mm群に比べて有意に少なかった（p＜0.0001）。Hazeに関しては，術後すべての時点で両群に有意差はみられなかった（p＝0.16〜p＝0.21）。また，6mm群では術後経過中にhaloの訴えは少ないものの，5mm群に比べcentrai islandの高い発生をみた。術後6か月の時点では両群ともに良好な術後成績が得られた。6mm照射径では，central islandの発生率は高いものの，術後屈折変化，予測性，裸眼視力の早期回復，haloの予防において優れていると思われた。

We reviewed 90 myopic eyes treated by excimer laser photorefractive keratectomy. Omnimed excimer laser with 6mm ablation zone was used in 45 eyes and Eximed excimer laser with 5mm ablation zone was used in 45 eyes. All the eyes had myopia of 6 diopters or less. Both groups were matched for preoperative myopia, gender and age. Eyes in the 5mm group showed greater hyperopic shift than those in the 6mm group at 1, 3 and 6 months after treatment. The differences were significant (p ＜ 0.0001 to p ＜ 0.01) . Eyes in 6mm group showed lesser variance of refraction under cycloplegia than those in 5mm group at all postoperative periods (p ＜ 0.0001). Both groups showed no significant differences regarding haze at all postoperative periods (p = 0.16 to p =0.21) . Night halo was more frequent in the 5mm group at all postoperative periods. The incidence of central island was higher in the 6mm group. The overall refractive improvement was good in both groups. Eyes in the 6mm group showed more predictive results, more rapid recovery of uncorrected visual acuity and lesser side effects as night halo in spite of higher incidence of central island.