Alió J L, Ismail M M, Sanchéz Pego J L
Department of Ophthalmology, Instituto Oftalmologico de Alicante, Spain.
J Refract Surg. 1997 Jan-Feb;13(1):17-22. doi: 10.3928/1081-597X-19970101-07.
To assess the potential of non-contact holmium:YAG laser thermal keratoplasty to safely and effectively correct hyperopia up to +5.00 diopters (D).
Non-contact laser thermal keratoplasty with a holmium:YAG laser using energies ranging from 215 to 255 mJ with 6, 7, and 8-min ablation zone diameters, was applied to 57 sighted eyes of 42 hyperopic patients in a controlled study. All patients were followed for 15 months after surgery.
Preoperative spectacle-corrected visual acuity returned to baseline levels from 2 to 6 weeks after treatment. Regression of effect was evident in all eyes, and after 15 months was total in 18 eyes (31.5%). The mean cycloplegic refraction before surgery was +3.80 +/- 0.22 D (range, +1.50 to +5.00 D); after surgery, it was +1.40 +/- 0.12 at 3 months, +1.69 +/- 0.19 D at 6 to 8 months, and +1.73 +/- 0.16 D at 15 months. At the end of the study, 41 eyes (71.9%) had an uncorrected visual acuity of 20/40 or better. Thirty-two eyes (58.8%) were within +/- 1.00 D of the intended refraction. Patient age and central pachymetric values were significantly correlated with regression (ANOVA, (p less than .005).
Regression of initial effect can be large with non-contact holmium:YAG laser thermal keratoplasty. We think the technique works best up to +3.00 D in older individuals with central corneal thickness less than 525 microns. Algorithms to improve the final results should include an initial calculated overcorrection adjusted on variables that influence regression such as patient age and corneal thickness.
评估非接触钬激光热角膜成形术安全有效地矫正高达+5.00屈光度（D）远视的潜力。
在一项对照研究中，对42例远视患者的57只眼进行非接触钬激光热角膜成形术，使用的能量范围为215至255 mJ，消融区直径分别为6、7和8分钟。所有患者术后随访15个月。
治疗后2至6周，术前眼镜矫正视力恢复至基线水平。所有眼睛均出现明显的效果消退，15个月后18只眼（31.5%）完全消退。术前平均睫状肌麻痹验光为+3.80±0.22 D（范围为+1.50至+5.00 D）；术后3个月为+1.40±0.12 D，6至8个月为+1.69±0.19 D，15个月为+1.73±0.16 D。研究结束时，41只眼（71.9%）的裸眼视力达到20/40或更好。32只眼（58.8%）的屈光度数在预期屈光度的±1.00 D范围内。患者年龄和中央角膜厚度值与效果消退显著相关（方差分析，p<0.005）。
非接触钬激光热角膜成形术的初始效果消退可能较大。我们认为该技术在中央角膜厚度小于525微米的老年个体中，矫正+3.00 D以下的远视效果最佳。改善最终结果的算法应包括根据影响效果消退的变量（如患者年龄和角膜厚度）进行初始计算的过度矫正。
