エキシマレーザー屈折矯正術後のcentral islandの視力への長期的影響

Longterm influence of central island on the visual acuity following photorefractive keratectomy

（25D-1）　Visx Twenty／Twenty Excimer Laser Systemで，Ver.3.2とVer.4.0〔central island（Cl）発生予防プログラム〕の2種類のアルゴリズムを使用し，術前の矯正視力が1.0以上を示す30例55眼に対してエキシマレーザー屈折矯正術（photorefractive keratectomy：PRK）を施行した。術後1か月に角膜形状解析を行つてClの有無を判定した。Ver.4.0ではClを認めなかつたため，Ver.3.2のCl（＋）群，Ver.3.2のCl （−）群，Ver.4.0のCl （−）群の3群で，術前，および術後2年までの矯正視力を比較検討した。術後1年までは3群間に有意な差を認め，PRK後のCl発生に対する予防プログラムの長期的な有用性が示された。

We performed photorefractive keratectomy (PRK) on 55 myopic eyes using a Twenty/Twenty Excimer Laser System (Visx) . All the eyes showed good preoperative corrected visual acuity. PRK was perfomed using either of the two algorithms : Version 3.2 and Version 4.0 which was modified to decrease the postoperative central island. When examined one month after PRK, the central island was present in 7 and absent in 16 eyes out of 23 eyes treated with Version 3.2. Out of 32 eyes treated with Version 4.0, no eye showed the central island. Three groups were compared regarding the best corrected visual acuity until two years after PRK. Significant differences were present among the three groups until one year after surgery, showing the longterm value of Version 4.0 in preventing the post-PRK central island.