Ophthalmology Department, Fundación Jiménez Díaz University Hospital, Madrid, Spain.
Centre for Microsystems Technology (CMST), Ghent University and Imec, Technologiepark, Ghent, Belgium.
Transl Vis Sci Technol. 2022 Mar 2;11(3):19. doi: 10.1167/tvst.11.3.19.
The purpose of this study was to assess the impact of different intracorneal ring segments (ICRS) combinations on corneal morphology and visual performance on patients with keratoconus.
A total of 124 eyes from 96 patients who underwent ICRS surgery were analyzed and classified into 7 groups based on ICRS disposition and the diameter of the surgical zone (5- and 6-mm). Pre- and postoperative complete ophthalmological examinations were conducted. Corneal geometry, volume, and symmetry were studied. Zernike polynomials were used to build a virtual ray-tracing model to evaluate optical aberrations and the Visual Strehl (VS).
ICRS induced significant flattening across the cornea, being more pronounced on the anterior (+0.38 mm, P < 0.001) than on the posterior (+0.15 mm, P < 0.001) corneal radius. Asphericity experienced a larger change for a 6-mm surgical zone diameter (from -1.23 ± 1.1 to -1.86 ± 1.2, P < 0.001) than for a 5-mm zone (from -1.99 ± 1.1 to -2.10 ± 1.5, P = 0.536). Mean astigmatism was reduced by 2.05 D (P < 0.001). Combination four was the most effective in reducing astigmatism. Coma decreased by 30% on average and combination one produced an average reduction by 51% (P < 0.05). Patients experienced significant improvement in visual performance, best corrected visual acuity increased from 0.57 ± 0.21 to 0.69 ± 0.21 and VS changed from 0.049 ± 0.02 to 0.065 ± 0.041.
ICRS combinations implanted within 5 mm diameter zone are more effective in flattening the cornea, whereas those implanted on 6 mm diameter are as effective in reducing astigmatism and are a good choice if the asymmetry and the intended flattening are smaller. Combinations with asymmetrical implants are the best option to regularize corneal surface.
This study uses methods and metrics of optical research applied to daily clinical practice.
本研究旨在评估不同的角膜内环段（ICRS）组合对圆锥角膜患者角膜形态和视觉性能的影响。
对 96 例 124 只眼接受 ICRS 手术的患者进行分析，并根据 ICRS 位置和手术区直径（5mm 和 6mm）将其分为 7 组。术前和术后进行全面眼科检查。研究角膜几何形状、体积和对称性。使用泽尼克多项式构建虚拟光线追踪模型，以评估像差和视觉斯特雷尔（VS）。
ICRS 导致角膜明显变平，在前部（+0.38mm，P<0.001）比后部（+0.15mm，P<0.001）更明显。对于 6mm 手术区直径，非球面性变化较大（从-1.23±1.1 变为-1.86±1.2，P<0.001），而对于 5mm 区，从-1.99±1.1 变为-2.10±1.5，P=0.536）。平均散光减少 2.05D（P<0.001）。组合四在减少散光方面最有效。平均平均散光减少 30%，组合一平均减少 51%（P<0.05）。患者的视觉性能显著改善，最佳矫正视力从 0.57±0.21 增加到 0.69±0.21，VS 从 0.049±0.02 增加到 0.065±0.041。
植入 5mm 直径区内的 ICRS 组合在使角膜变平时更有效，而植入 6mm 直径区内的组合在减少散光方面同样有效，如果不对称性和预期变平较小，则是一个不错的选择。具有不对称植入物的组合是使角膜表面规则化的最佳选择。
石冰冰
