Abad J C, An B, Power W J, Foster C S, Azar D T, Talamo J H
Massachusetts Eye and Ear Infirmary, Department of Ophthalmology, Harvard Medical School, Boston, USA.
Ophthalmology. 1997 Oct;104(10):1566-74; discussion 1574-5. doi: 10.1016/s0161-6420(97)30095-5.
The purpose of the study is to compare alcohol-assisted versus mechanical debridement of the corneal epithelium before photorefractive keratectomy (PRK) for low-to-moderate myopia.
A prospective study was performed on a group of consecutive patients operated on at the Massachusetts Eye and Ear Infirmary from February to April 1996 and followed for 6 months.
Eighty patients (eyes) were divided in 2 groups: 40 alcohol and 40 mechanical.
The patients underwent PRK for myopia (-1.5 to -7.5 diopters) with a Summit Apex excimer laser. The corneal epithelium was removed either with 20% ethanol or with a scalpel blade.
The two groups were compared for epithelial removal time, epithelial defect size at the end of surgery, and rate of re-epithelialization. Uncorrected visual acuity (UCVA), refractive outcome, best-corrected visual acuity (BCVA), and subjective haze were measured at 4 days and at 1, 3, and 6 months. In an additional short-term study, 40 patients (20 alcohol, 20 mechanical) had intraoperative pachymetry performed.
Alcohol-assisted de-epithelialization was faster than mechanical debridement (107 [+/-20.6 standard deviation] versus 141 [+/-30.5] seconds [P < 0.0001]) and led to a more circumscribed and reproducible epithelial defect at the end of surgery (87,739 [+/-11,852] versus 103,518 [+/-33,942] square pixels [t test, P = 0.04; f test, P = 0.001]). At 4 days, 95% of the alcohol-treated patients had healed compared with 78% of the mechanically scraped patients (Fisher's exact test, P = 0.04). The alcohol group had a better UCVA at 4 days (logarithm of the minimum angle of resolution UCVA 0.36 [+/-0.22] versus 0.51 [+/-0.26]) and at 1 month (0.14 [+/-0.17] versus 0.22 [+/-0.16] [Mann-Whitney U test, P = 0.02 and P = 0.03]) but equalized at 3 months (0.10 [+/-0.14] versus 0.13 [+/-0.16]) and at 6 months (0.11 [+/-0.15] versus 0.14 [+/-0.13] [Mann-Whitney U test, P = 0.23 and P = 0.34]). There was a trend toward less subjective haze in the alcohol-treated patients over the course of the study (area under the curve, 71.9 [+/-35.3] versus 87.9 [+/-33.8] [Mann-Whitney U test, P = 0.07]). The difference from target was equivalent in both groups at 6 months (-0.22 [+/-0.58] diopter in the alcohol group and -0.43 [+/-0.52] diopter in the mechanical group [t test, P = 0.14; f test, P = 0.57]). There were no differences in intraoperative pachymetry, corneal uniformity index as calculated from the corneal topography, and loss of BCVA between the two groups.
Twenty percent ethanol is a simple, safe, and effective alternative to mechanical scraping before PRK and appears to be associated with a quicker visual rehabilitation.
本研究旨在比较准分子激光原位角膜磨镶术（PRK）治疗中低度近视前，酒精辅助去除角膜上皮与机械去除角膜上皮的效果。
对1996年2月至4月在马萨诸塞州眼耳医院连续接受手术的一组患者进行前瞻性研究，并随访6个月。
80例患者（80只眼）分为两组：40例采用酒精法，40例采用机械法。
患者使用Summit Apex准分子激光进行近视（-1.5至-7.5屈光度）PRK手术。角膜上皮用20%乙醇或手术刀去除。
比较两组的上皮去除时间、手术结束时上皮缺损大小和上皮再形成率。在术后4天、1个月、3个月和6个月测量未矫正视力（UCVA）、屈光结果、最佳矫正视力（BCVA）和主观 haze。在另一项短期研究中，40例患者（20例酒精法，20例机械法）进行了术中测厚。
酒精辅助上皮去除术比机械清创术更快（107[±20.6标准差]秒对141[±30.5]秒[P<0.0001]），且在手术结束时导致更局限且可重复的上皮缺损（87,739[±11,852]对103,518[±33,942]平方像素[t检验，P = 0.04；F检验，P = 0.001]）。在4天时，95%接受酒精治疗的患者已愈合，而机械刮除患者为78%（Fisher精确检验，P = 0.04）。酒精组在4天时UCVA更好（最小分辨角对数UCVA 0.36[±0.22]对0.51[±0.26]）和1个月时（0.14[±0.17]对0.22[±0.16][Mann-Whitney U检验，P = 0.02和P = 0.03]），但在3个月时（0.10[±0.14]对0.13[±0.16]）和6个月时（0.11[±0.15]对0.14[±0.13][Mann-Whitney U检验，P = 0.23和P = 0.34]）趋于相等。在研究过程中，酒精治疗患者的主观haze有减少趋势（曲线下面积，71.9[±35.3]对87.9[±33.8][Mann-Whitney U检验，P = 0.07]）。两组在6个月时与目标值的差异相当（酒精组为-0.22[±0.58]屈光度，机械组为-0.43[±0.52]屈光度[t检验，P = 0.14；F检验，P = 0.57]）。两组在术中测厚、根据角膜地形图计算的角膜均匀性指数以及BCVA损失方面无差异。
20%乙醇是PRK术前机械刮除的一种简单、安全且有效的替代方法，似乎与更快的视力恢复相关。
