Grosvenor T
School of Optometry, Indiana University, Bloomington, USA.
Optom Vis Sci. 1995 Oct;72(10):698-712. doi: 10.1097/00006324-199510000-00002.
At the close of 1994, the AOA News reported that at least 14 companies were preparing to market equipment for excimer laser photorefractive keratectomy (PRK). More than a dozen PRK centers had been formed for the purpose of recruiting optometrists to co-manage PRK patients. Because the surgery is a "no-touch" computer-driven procedure whose duration is measured in seconds, the preoperative and postoperative care of PRK patients will assume major importance. Optometrists who will be asked to take part in the management of PRK patients must be able to counsel patients on matters such as the predictability of the procedure in terms of postoperative refractive error and visual acuity, as well as the possibility of unintended consequences such as difficulty in night driving. Information currently available, mainly as a result of studies conducted in other countries, shows that the results of PRK are highly predictable for preoperative myopia up to about -3.00 D and somewhat less predictable for myopia between -3.00 and -6.00 D, whereas for myopia greater than -6.00 D the probability of achieving a full correction decreases rapidly with increasing amounts of myopia. As compared to radial keratotomy (RK) in which the postoperative refractive error drifts relentlessly in the hyperopic direction, PRK brings about an initial hyperopic shift followed by regression leading to increasing myopia. Researchers disagree on the cause of the postoperative hyperopic shift and regression, and on the value of various methods of controlling regression including the use of wider and deeper ablation profiles and the postoperative use of corticosteroids and nonsteroid anti-inflammatory drugs. It is too early to determine whether the myopic creep in PRK will be as persistent as the hyperopic creep in RK, but it is likely that whereas presbyopic post-RK patients may have adequate distance vision but require corrective lenses for reading, presbyopic post-PRK patients may be sufficiently myopic to require lenses for distance vision but not for reading.
1994年末，《美国眼科学会新闻》报道，至少有14家公司正准备将准分子激光屈光性角膜切削术（PRK）设备推向市场。为招募验光师共同管理PRK患者，已成立了十几家PRK中心。由于该手术是一种“非接触式”计算机驱动的手术，手术时间以秒计算，因此PRK患者的术前和术后护理将变得至关重要。被要求参与PRK患者管理的验光师必须能够就手术在术后屈光不正和视力方面的可预测性，以及诸如夜间驾驶困难等意外后果的可能性等问题为患者提供咨询。目前可获得的信息，主要是其他国家开展研究的结果，表明PRK对于术前近视度数高达约-3.00 D的患者，手术结果具有高度可预测性；对于近视度数在-3.00 D至-6.00 D之间的患者，可预测性稍低；而对于近视度数大于-6.00 D的患者，随着近视度数增加，实现完全矫正的概率迅速降低。与放射状角膜切开术（RK）相比，RK术后屈光不正会持续向远视方向漂移，而PRK会导致初始远视偏移，随后出现回退，导致近视增加。研究人员对于术后远视偏移和回退的原因，以及包括使用更宽更深的消融模式和术后使用皮质类固醇及非甾体抗炎药等各种控制回退方法的价值存在分歧。现在确定PRK中的近视蠕变是否会像RK中的远视蠕变一样持续还为时过早，但很可能RK术后的老花眼患者可能有足够的远视力，但阅读时需要矫正镜片，而PRK术后的老花眼患者可能近视程度足以需要戴镜片矫正远视力，但阅读时不需要。
