Goggin M, Lavery F
Wellington Eye Clinic, Dublin, Republic of Ireland.
Br J Ophthalmol. 1997 Jul;81(7):541-3. doi: 10.1136/bjo.81.7.541.
Overcorrection following myopic photorefractive keratectomy, with a target of emmetropia, leaving a spherical equivalent of more than 1.0 D of hyperopia is of the order of 1%. This study analyses the efficacy, safety, and 1 year stability of outcome of laser thermokeratoplasty (LTK) carried out on eyes with persistent symptomatic hyperopia following photorefractive keratectomy (PRK) for myopia.
11 consecutive eyes in 11 patients underwent LTK using the Technomed Holmium 25, contact holmium:YAG laser system. The mean spherical equivalent before LTK was +2.06 D (SD 1.02 D, range +1.00 D to +4.75 D) based on a non-cycloplegic refraction. Between four and 16 burns were used per eye, depending on the error to be corrected.
The mean spherical equivalent was +0.511 D (SD 0.551) at 1 year. Ten of the 11 eyes were seeing 6/12 or greater, unaided (91%) and nine were within 1.0 D of the target sphere equivalent (82%). Recovery of unaided acuity occurred during the first week in four cases and the first month in the rest. One eye lost greater than one line of best corrected vision (9%), going from 6/5 to 6/7.5 and one gained a line (9%), 6/12 to 6/7.5. No complications occurred during the follow up period.
In this study of a small number of eyes with hyperopia induced by PRK, LTK appears safe, predictable, and stable for low errors followed for 1 year.
近视性准分子激光角膜切削术后以正视化为目标进行过度矫正，导致等效球镜度超过1.0 D远视的发生率约为1%。本研究分析了对近视性准分子激光角膜切削术（PRK）后持续存在症状性远视的眼睛进行激光热角膜成形术（LTK）的疗效、安全性及1年结果稳定性。
11例患者的11只眼睛连续接受了使用Technomed钬25接触式钬：YAG激光系统的LTK治疗。基于非睫状肌麻痹验光，LTK术前平均等效球镜度为+2.06 D（标准差1.02 D，范围+1.00 D至+4.75 D）。每只眼睛根据需要矫正的误差进行4至16次烧灼。
1年后平均等效球镜度为+0.511 D（标准差0.551）。11只眼睛中有10只（91%）无需辅助视力达到6/12或更好，9只（82%）在目标等效球镜度的1.0 D范围内。4例患者在第一周恢复了无需辅助的视力，其余患者在第一个月恢复。1只眼睛最佳矫正视力下降超过1行（9%），从6/5降至6/7.5，1只眼睛提高了1行（9%），从6/12提高到6/7.5。随访期间未发生并发症。
在这项针对少量PRK诱导的远视眼的研究中，LTK对于低误差且随访1年的情况似乎是安全、可预测且稳定的。
