Munger R, Dohadwala A A, Hodge W G, Jackson W B, Mintsioulis G, Damji K F
University of Ottawa Eye Institute, Ottawa Hospital, Ottawa, Ontario, Canada.
J Cataract Refract Surg. 2001 Aug;27(8):1254-62. doi: 10.1016/s0886-3350(01)00971-3.
To investigate the effect of hyperopic photorefractive keratectomy (PRK) on intraocular pressure (IOP) measurements.
University of Ottawa Eye Institute, Ottawa Hospital, Ottawa, Canada.
In this retrospective cohort study, IOP and central corneal thickness (CCT) were measured preoperatively and at 1, 2, 3, 6, 12, 18, and 24 months in 191 eyes that had hyperopic PRK with the VISX Star excimer laser. All corrections applied were between +1.00 and +6.50 diopters (D) of sphere and less than 3.75 D of cylinder.
At all postoperative examinations, the mean IOP in the hyperopic PRK group was 1.0 to 1.8 mm Hg lower than the preoperative IOP (P <.001). A large range of IOP changes was found across the population; eg, at 6 months, 49% of the eyes had a change in IOP from baseline of at least +/-3 mm Hg. A mean reduction of 19 microm of CCT was found with pachymetry after surgery (P < .001). The change in IOP readings postoperatively was not correlated with age, sex, keratometric readings, or applied correction. Changes in IOP were strongly correlated with preoperative IOP at all time points and with preoperative CCT at 18 and 24 months (P < .001). After hyperopic PRK, the measured IOP was more likely to increase in patients with preoperative IOPs less than 14.5 mm Hg and more likely to decrease in patients with preoperative IOPs above 14.5 mm Hg.
Changes in IOP after hyperopic PRK were similar to changes after myopic PRK, despite only minimal changes in the CCT. This suggests that hyperopic PRK results in biomechanical effects that modify the elastic properties of the cornea beyond the changes in rigidity expected from central corneal thinning. There was a strong negative correlation between the measured preoperative IOP and the change in IOP postoperatively that was likely the result of regression of the mean effect.
研究远视性准分子激光角膜切削术（PRK）对眼压（IOP）测量的影响。
加拿大渥太华渥太华医院渥太华大学眼科学院。
在这项回顾性队列研究中，对191只接受VISX Star准分子激光远视性PRK手术的眼睛，在术前以及术后1、2、3、6、12、18和24个月测量眼压和中央角膜厚度（CCT）。所有矫正度数范围为球镜度数+1.00至+6.50屈光度（D），柱镜度数小于3.75 D。
在所有术后检查中，远视性PRK组的平均眼压比术前眼压低1.0至1.8 mmHg（P <.001）。整个人群中眼压变化范围很大；例如，在术后6个月时，49%的眼睛眼压相对于基线的变化至少为±3 mmHg。术后经角膜厚度测量发现CCT平均减少了19微米（P <.001）。术后眼压读数的变化与年龄、性别、角膜曲率读数或矫正度数无关。在所有时间点，眼压变化与术前眼压密切相关，在术后18个月和24个月时与术前CCT密切相关（P <.001）。远视性PRK术后，术前眼压低于14.5 mmHg的患者测量得到的眼压更有可能升高，而术前眼压高于14.5 mmHg的患者测量得到的眼压更有可能降低。
远视性PRK术后眼压的变化与近视性PRK术后的变化相似，尽管CCT仅有微小变化。这表明远视性PRK会产生生物力学效应，改变角膜的弹性特性，超出了中央角膜变薄所预期的硬度变化。术前测量的眼压与术后眼压变化之间存在很强的负相关性，这可能是平均效应消退的结果。
