Artola Alberto, Patel Sudi, Schimchak Patricia, Ayala María J, Ruiz-Moreno José M, Alió Jorge L
Research, Development, and Innovation Department, Vissum, Institute of Ophthalmology and School of Medicine, University Miguel Hernández, Alicante, Spain.
Ophthalmology. 2006 May;113(5):735-41.e1. doi: 10.1016/j.ophtha.2006.01.054.
To evaluate uncorrected near visual acuity (NVA), accommodation, corneal aberrations, and the optical quality of the retinal image in presbyopic eyes after photorefractive keratectomy (PRK).
Nonrandomized comparative retrospective study.
Ten post-PRK patients and 10 normal patients.
Twenty eyes (10 right and 10 left after PRK for myopia, minimum of 10 years after the operation; group A) were compared with 20 eyes (10 right and 10 left age- and gender-matched normal controls; group B). All subjects were over 40 years of age.
With best distance correction, NVA was measured at 40 cm (Jaeger, J series), and the range of accommodation (diopters [D]) was measured subjectively (negative relative amplitude and positive relative amplitude). The modulation transfer function (MTF) and corneal aberrations such as comalike, spherical (SAs), and higher order (HOAs) were measured with a Hartmann-Shack aberrometer. From the MTF curves, the spatial frequencies corresponding to contrast values of 0.1 and 0.5 were noted.
Mean ages (+/- standard deviations [SDs]) were 46.3 years (4.7) for group A and 47.6 years (4.9) for group B (P>0.05). Near acuity was J1 or better in 12 of 20 post-PRK and 4 of 20 control eyes. Mean accommodations (+/- SDs) were 3.2 D (1.14) for right group A eyes and 2.1 D (0.94) for right group B eyes (P = 0.0152), and 3.4 D (0.99) for left A eyes and 2.3 D (1.02) for left B eyes (P = 0.0168). Total HOA indexes (+/- SDs) were 1.449 (0.409) for right group A eyes and 0.824 (0.241) for right group B eyes (P = 0.008), and 1.464 (0.388) for left A eyes and 1.067 (0.542) for left B eyes (P = 0.0752). Pooling the data from post-PRK and control eyes, a significant correlation was found between near acuity and SA (right eyes, r = -0.535, P = 0.015; left eyes, r = -0.493, P = 0.027). Significant associations were found between accommodation, near acuity, HOA, and comalike aberration for right eyes only. Mean spatial frequencies (+/- SDs) corresponding to contrast values of 0.1 for right and left eyes were 14.96 (5.71) for right group A eyes and 22.02 (6.85) for right group B eyes (P = 0.074), and 15.11 (7.80) for left A eyes and 21.41 (9.00) for left B eyes (P = 0.271). Mean spatial frequencies (+/- SDs) corresponding to contrast values of 0.5 for right and left eyes were 2.86 (0.63) for right group A eyes and 3.21 (0.35) for right group B eyes (P = 0.596), and 2.76 (0.98) for left A eyes and 3.22 (0.27) for left B eyes (P = 0.194).
Compared with normal eyes, in previously myopic eyes treated with first-generation PRK lasers there is a tendency for (1) the optical quality of the retinal image to be reduced at low contrast, (2) the aberrations attributed to the corneal surface to increase, and (3) both measured subjective accommodation and near acuity to be greater than expected. We postulate that the corneal aberrations induced by PRK for myopia may reduce the quality of the retinal image for distance but enhance near acuity by way of a multifocal effect that can delay the onset of age-related near vision symptoms.
评估准分子激光原位角膜磨镶术（PRK）后老花眼中未矫正的近视力（NVA）、调节功能、角膜像差以及视网膜图像的光学质量。
非随机对照回顾性研究。
10例PRK术后患者和10例正常患者。
将20只眼（近视PRK术后，至少术后10年，10只右眼和10只左眼；A组）与20只眼（年龄和性别匹配的正常对照，10只右眼和10只左眼；B组）进行比较。所有受试者年龄均超过40岁。
在最佳远距离矫正下，测量40cm处的NVA（Jaeger，J系列），并主观测量调节范围（屈光度[D]）（负相对调节幅度和正相对调节幅度）。使用哈特曼-夏克像差仪测量调制传递函数（MTF）和角膜像差，如彗差、球差（SAs）和高阶像差（HOAs）。从MTF曲线中，记录对应于对比度值0.1和0.5的空间频率。
A组平均年龄（±标准差[SDs]）为46.3岁（4.7），B组为47.6岁（4.9）（P>0.05）。20只PRK术后眼中12只、20只对照眼中4只的近视力为J1或更好。A组右眼平均调节（±SDs）为3.2D（1.14），B组右眼为2.1D（0.94）（P = 0.0152）；A组左眼为3.4D（0.99），B组左眼为2.3D（1.02）（P = 0.0168）。A组右眼总HOA指数（±SDs）为1.449（0.409），B组右眼为0.824（0.241）（P = 0.008）；A组左眼为1.464（0.388），B组左眼为1.067（0.542）（P = 0.0752）。汇总PRK术后眼和对照眼的数据，发现近视力与球差之间存在显著相关性（右眼，r = -0.535，P = 0.015；左眼，r = -0.493，P = 0.027）。仅在右眼中发现调节、近视力、HOA和彗差之间存在显著关联。对应于对比度值0.1的右眼和左眼平均空间频率（±SDs），A组右眼为14.96（5.71），B组右眼为22.02（6.85）（P = 0.074）；A组左眼为15.11（7.80），B组左眼为21.41（9.00）（P = 0.271）。对应于对比度值0.5的右眼和左眼平均空间频率（±SDs），A组右眼为2.86（0.63），B组右眼为3.21（0.35）（P = 0.596）；A组左眼为2.76（0.98），B组左眼为3.22（0.27）（P = 0.194）。
与正常眼相比，在接受第一代PRK激光治疗的既往近视眼中，存在以下趋势：（1）低对比度下视网膜图像的光学质量降低；（2）归因于角膜表面的像差增加；（3）测量的主观调节和近视力均大于预期。我们推测，近视PRK引起的角膜像差可能会降低远距离视网膜图像的质量，但通过多焦点效应提高近视力，从而可以延迟与年龄相关的近视力症状的出现。
