Refai Tamer Adel
MD, FRCS, Refractive Unit, Ophthalmology Department, Research Institute of Ophthalmology, Giza, Egypt.
Electron Physician. 2015 Sep 16;7(5):1296-300. doi: 10.14661/1296. eCollection 2015 Sep.
LASIK surgery is currently the preferred procedure to correct low to moderate myopia. The aim of this study was to determine the orientation of the steepest meridian of regular astigmatism in order to determine the relative incidence of vertical, horizontal, and oblique regular astigmatism among highly myopic Egyptian patients seeking non-ablative surgical correction of the refractive error.
One hundred and one eyes of 68 highly myopic patients who were seeking refractive surgery were included in this consecutive case series study. The refractive errors were measured using an autorefractometer and confirmed by trial. We measured the uncorrected and best corrected visual acuity in Snellen lines. Keratometry, central corneal thickness, and anterior chamber depth also were measured. The cylinder power in diopters and the axis in degrees were reported. Astigmatism was graded as with the rule (i.e., vertical meridian steeper), against the rule (i.e., horizontal meridian steeper), and oblique astigmatism. The number and the percentage of eyes with the rule, against the rule, and oblique astigmatism were calculated, and the chi-squared test was performed to analyze the data.
The spherical refractive error ranged from -6.5 to -24.5 diopters (-13.45 ± 4.60). The cylinder power (Cyl) ranged from -0.25 to -7.5 diopters (-2.23 ± 1.28). The uncorrected visual acuity (UCVA) in Snellen lines ranged from 0.01 - 0.1 (0.03 ± 0.02). The mean for best corrected visual acuity (BCVA) in Snellen lines was 0.40 (± 0.23). The steepest meridian was vertical (i.e., with-the-rule astigmatism) in 44 eyes (43.56%), horizontal (i.e., against-the-rule astigmatism) in 27 eyes (26.73%), and oblique (i.e., oblique astigmatism) in 30 eyes (29.70%).
The incidence of with-the-rule astigmatism in patients with high myopia was found to be much lower than in previous studies for non-myopic patients, with a higher incidence for against-the-rule astigmatism and oblique astigmatism.
准分子原位角膜磨镶术（LASIK）目前是矫正轻度至中度近视的首选手术。本研究的目的是确定规则散光最陡子午线的方向，以确定在寻求非消融性屈光不正手术矫正的高度近视埃及患者中，垂直、水平和斜向规则散光的相对发生率。
本连续病例系列研究纳入了68例寻求屈光手术的高度近视患者的101只眼。使用自动验光仪测量屈光不正，并通过试镜进行确认。我们用斯内伦视力表测量了未矫正和最佳矫正视力。还测量了角膜曲率、中央角膜厚度和前房深度。报告了屈光度的柱镜度数和轴位度数。散光分为顺规（即垂直子午线较陡）、逆规（即水平子午线较陡）和斜向散光。计算了顺规、逆规和斜向散光眼的数量及百分比，并进行卡方检验以分析数据。
球镜屈光不正范围为-6.5至-24.5屈光度（-13.45±4.60）。柱镜度数（Cyl）范围为-0.25至-7.5屈光度（-2.23±1.28）。斯内伦视力表的未矫正视力（UCVA）范围为0.01 - 0.1（0.03±0.02）。斯内伦视力表的最佳矫正视力（BCVA）平均值为0.40（±0.23）。最陡子午线为垂直方向（即顺规散光）的有44只眼（43.56%），水平方向（即逆规散光）的有27只眼（26.73%），斜向（即斜向散光）的有30只眼（29.70%）。
发现高度近视患者中顺规散光的发生率远低于先前针对非近视患者的研究，逆规散光和斜向散光的发生率较高。
