From the LaserVision Clinical & Research Eye Institute, Athens, Greece (Vingopoulos, Zisimopoulos, Kanellopoulos); New York University Medical School, New York, New York (Kanellopoulos).
J Cataract Refract Surg. 2022 Jan 1;48(1):83-88. doi: 10.1097/j.jcrs.0000000000000691.
To describe the concordance of keratoconus (KC) expression in 2 pairs of monozygotic twins before and after a combined corneal crosslinking (CXL)/photorefractive keratectomy (PRK) procedure.
Private ambulatory eye surgery unit.
Retrospective interventional twin study.
Two pairs of male monozygotic twins with KC were studied retrospectively. Improvement of flattest (K1) and steepest (K2) keratometry, index of height decentration (IHD), and corneal thickness at the thinnest point and corneal epithelial thickness measured by anterior segment optical coherence tomography and Scheimpflug tomography was compared between respective eyes of monozygotic twin siblings 1 to 5 years after the application of combined CXL and topography-guided PRK of part of the refractive error (the Athens Protocol).
Significant improvement was noted in all the keratometric indices of all 8 eyes after the combined CXL/PRK procedure. The difference in K1, K2, IHD, corneal thickness at the thinnest point, and corneal epithelial thickness percentage improvement between the right eyes of each pair of twins was statistically significant 1 year and 5 years postoperatively (P < .05). Statistically significant discordance in the aforementioned parameters percentage improvement was similarly observed between the left eyes of each pair of twins (P < .05).
Although a genetic predisposition in KC is well documented, the discordance in keratometric indices improvement after a CXL/PRK procedure between respective eyes of monozygotic twins suggests that environmental influences may contribute to the disease expression as well. Variable degree of synergy in a combined CXL/PRK procedure may also explain the aforementioned discordant improvement.
描述 2 对接受角膜交联术（CXL）/准分子激光角膜切削术（PRK）联合治疗前后的同卵双胞胎的圆锥角膜（KC）表现的一致性。
私人门诊眼科手术单位。
回顾性干预性双胞胎研究。
回顾性研究了 2 对患有 KC 的男性同卵双胞胎。通过眼前节光学相干断层扫描和 Scheimpflug 断层扫描，比较了 CXL 和部分屈光不正的 topography-guided PRK 联合治疗后 1 至 5 年时，同卵双胞胎同胞各自眼睛的最平坦（K1）和最陡峭（K2）角膜曲率计值、高度偏心指数（IHD）、角膜最薄点的角膜厚度和角膜上皮厚度的改善情况（雅典协议）。
在接受联合 CXL/PRK 手术后，所有 8 只眼的所有角膜曲率计指数均有显著改善。每对双胞胎右眼之间的 K1、K2、IHD、角膜最薄点厚度和角膜上皮厚度百分比改善差异在术后 1 年和 5 年均有统计学意义（P <.05）。同样，每对双胞胎左眼之间的上述参数百分比改善也存在显著的不一致（P <.05）。
尽管 KC 的遗传易感性已有充分记录，但 CXL/PRK 手术后各自眼睛的角膜曲率计指数改善程度的不一致表明，环境影响也可能导致疾病的表现。联合 CXL/PRK 手术中的协同作用程度不同也可以解释上述不一致的改善。
