Department of Ophthalmology, Massachusetts Eye and Ear, Harvard Medical School, Boston, MA, USA.
Schepens Eye Research Institute, Boston Keratoprosthesis Laboratory, Massachusetts Eye and Ear, Harvard Medical School, Boston, MA, USA.
Transl Vis Sci Technol. 2020 Nov 3;9(12):10. doi: 10.1167/tvst.9.12.10. eCollection 2020 Nov.
To benchmark the optical performance of Boston Keratoprosthesis (B-KPro).
Back focal lengths (BFL) of B-KPros for various eye axial lengths were measured using an optical bench, International Organization for Standardization-certified for intraocular lens characterization, and compared against manufacturer's specification. The modulation transfer function (MTF) and the resolution efficiencies were measured. The theoretical geometry-dependent higher-order aberrations (HOA) were calculated. The devices were characterized with optical profilometry for estimating the surface scattering. Aberration correction and subsequent image quality improvement were simulated in CODE-V. Natural scene-imaging was performed in a mock ocular environment. Retrospective analysis of 15 B-KPro recipient eyes were presented to evaluate the possibility of achieving 20/20 best-corrected visual acuity (BCVA).
BFL measurements were in excellent agreement with the manufacturer-reported values (r = 0.999). The MTF specification exceeded what is required for achieving 20/20 visual acuity. Astigmatism and field curvature, correctable in simulations, were the primary aberrations limiting imaging performance. Profilometry of the anterior surface revealed nanoscale roughness (root-mean-square amplitude, 30-50 nm), contributing negligibly to optical scattering. Images of natural scenes obtained with a simulated B-KPro eye demonstrated good central vision, with 10/10 visual acuity (equivalent to 20/20). Full restoration of 20/20 BCVA was obtainable for over 9 years in some patients.
Theoretical and experimental considerations demonstrate that B-KPro has the optical capacity to restore 20/20 BCVA in patients. Further image quality improvement can be anticipated through correction of HOAs.
We establish an objective benchmark to characterize the optics of the B-KPro and other keratoprosthesis and propose design changes to allow improved vision in B-KPro patients.
对波士顿角膜镜（B-KPro）的光学性能进行基准测试。
使用经过国际标准化组织认证的眼科人工晶状体特性测试光学平台，测量不同眼轴长度的 B-KPro 的后焦距（BFL），并与制造商的规格进行比较。测量调制传递函数（MTF）和分辨率效率。计算理论上依赖于几何形状的高阶像差（HOA）。使用光学轮廓术对设备进行特性描述，以估算表面散射。在 CODE-V 中进行像差校正和随后的图像质量改善的模拟。在模拟眼环境中进行自然场景成像。回顾性分析 15 例 B-KPro 受术眼，评估达到 20/20 最佳矫正视力（BCVA）的可能性。
BFL 测量值与制造商报告的值非常吻合（r=0.999）。MTF 规格超过了达到 20/20 视力所需的规格。可在模拟中校正的散光和场曲率是限制成像性能的主要像差。前表面的轮廓分析显示纳米级粗糙度（均方根幅度为 30-50nm），对光学散射的贡献可以忽略不计。使用模拟 B-KPro 眼获得的自然场景图像显示出良好的中心视力，视力为 10/10（相当于 20/20）。在一些患者中，超过 9 年可完全恢复 20/20 BCVA。
理论和实验考虑表明，B-KPro 具有恢复患者 20/20 BCVA 的光学能力。通过校正 HOAs，可以预期进一步提高图像质量。
郭雪
