Epstein D, Fagerholm P, Hamberg-Nyström H, Tengroth B
St. Erik's Eye Hospital, Karolinska Institute, Stockholm, Sweden.
Ophthalmology. 1994 Sep;101(9):1558-63; discussion 1563-4. doi: 10.1016/s0161-6420(94)31150-x.
To evaluate the 24-month refractive outcome of excimer laser photorefractive keratectomy (PRK) performed on normal, sighted myopic eyes; and to assess the evolution of postoperative refraction, the accuracy of predicted correction, and the results in terms of uncorrected visual acuity.
Photorefractive keratectomy was performed on 495 eyes, with a preoperative refraction ranging from -1.25 to -7.50 diopters (D). Ablation zone diameters of 4.3 and 4.5 mm were used. All patients were treated with a standard topical steroid regimen postoperatively. Minimum follow-up time was 24 months.
Mean refraction (spherical equivalent +/- standard deviation) at 24 months was -0.27 +/- 0.74 D, which was significantly (P < 0.01) different from the mean at 12 months (0.01 +/- 0.78 D). There was also a significant (P = 0.01) difference between the 12- and 18-month (-0.15 +/- 0.82 D) mean refractions. But there was no significant difference between the means at 18 and 24 months postoperatively. Subgroup analysis at 24 months showed that patients with low to moderate myopia (up to -3.90 D) had significantly better refractive outcomes than those with higher myopia. Also at 24 months, 91% of the eyes had an uncorrected visual acuity of at least 20/40, and 81.5% had an uncorrected visual acuity of at least 20/30. Correspondingly, 87.5% of the eyes were within 1.00 D of emmetropia, and 71.7% were within 0.50 D. Only 0.4% lost one line of best-corrected visual acuity, no eye lost two lines or more.
Refraction after PRK is slow to stabilize, but appears to reach stability by 18 to 24 months after surgery. The refractive results are reasonably predictable and compare well with those achieved with radial keratotomy.
评估准分子激光屈光性角膜切削术（PRK）对正常、有视力的近视眼睛的24个月屈光结果；并评估术后屈光的演变、预测矫正的准确性以及未矫正视力的结果。
对495只眼睛进行了屈光性角膜切削术，术前屈光度范围为-1.25至-7.50屈光度（D）。使用了4.3毫米和4.5毫米的消融区直径。所有患者术后均接受标准的局部类固醇治疗方案。最短随访时间为24个月。
24个月时的平均屈光（球镜等效度±标准差）为-0.27±0.74 D，与12个月时的平均值（0.01±0.78 D）有显著差异（P<0.01）。12个月和18个月时的平均屈光（-0.15±0.82 D）之间也有显著差异（P = 0.01）。但术后18个月和24个月时的平均值之间无显著差异。24个月时的亚组分析表明，低度至中度近视（高达-3.90 D）患者的屈光结果明显优于高度近视患者。同样在24个月时，91%的眼睛未矫正视力至少为20/40，81.5%的眼睛未矫正视力至少为20/30。相应地，87.5%的眼睛屈光不正度数在正视眼的1.00 D范围内，71.7%的眼睛在0.50 D范围内。只有0.4%的眼睛最佳矫正视力下降了一行，没有眼睛下降两行或更多。
PRK术后屈光稳定缓慢，但似乎在术后18至24个月达到稳定。屈光结果具有合理的可预测性，与放射状角膜切开术的结果相当。
