Background: Evaluation of corneal biomechanical properties 3 months after using rigid gas permeable (RGP) contact lenses in keratoconus.

Methods: In this prospective trial study, cases were 32 keratoconic eyes with no history of RGP lens wear. All eyes were examined with the Ocular Response Analyzer (ORA) and the Corneal Visualization Scheimpflug Technology (CORVIS-ST) to measure corneal hysteresis (CH), corneal resistance factor (CRF), deformation amplitude (DA), applanation velocity (AV) 1 and 2, applanation length (AL) 1 and 2, and peak distance before and 3 months after fitting aspheric RGP lenses. The effect of the correlation between contralateral eyes and maximum keratometry were controlled for in the analysis. Results were compared using repeated measures analysis of covariance.

Results: At 3 months, neither the increases in mean CH (0.14±2.77 mmHg, P=0.789), CRF (0.41±4.35 mmHg, P=0.612), AV1 (0.03±0.17 m/s, P=0.301), AV2 (0.11±0.59 m/s, P=0.299), AL1 (0.44±1.56 m/s, P=0.118), AL2 (1.16±5.06 m/s, P=0.211), and peak distance (0.19±1.29 m/s, P=0.409), nor the decrease in mean DA (0.03±0.17 mm, P=0.402) was statistically significant.

Conclusions: Results in our series of patients indicated that 3 months of RGP lens wear had no significant impact on corneal biomechanics, and perhaps non progression of keratoconus. Therefore, RGP lenses can be regarded safe and appropriate in keratoconic patients.

Background: Evaluation of corneal biomechanical properties 3 months after using rigid gas permeable (RGP) contact lenses in keratoconus.

Methods: In this prospective trial study, cases were 32 keratoconic eyes with no history of RGP lens wear. All eyes were examined with the Ocular Response Analyzer (ORA) and the Corneal Visualization Scheimpflug Technology (CORVIS-ST) to measure corneal hysteresis (CH), corneal resistance factor (CRF), deformation amplitude (DA), applanation velocity (AV) 1 and 2, applanation length (AL) 1 and 2, and peak distance before and 3 months after fitting aspheric RGP lenses. The effect of the correlation between contralateral eyes and maximum keratometry were controlled for in the analysis. Results were compared using repeated measures analysis of covariance.

Results: At 3 months, neither the increases in mean CH (0.14±2.77 mmHg, P=0.789), CRF (0.41±4.35 mmHg, P=0.612), AV1 (0.03±0.17 m/s, P=0.301), AV2 (0.11±0.59 m/s, P=0.299), AL1 (0.44±1.56 m/s, P=0.118), AL2 (1.16±5.06 m/s, P=0.211), and peak distance (0.19±1.29 m/s, P=0.409), nor the decrease in mean DA (0.03±0.17 mm, P=0.402) was statistically significant.

Conclusions: Results in our series of patients indicated that 3 months of RGP lens wear had no significant impact on corneal biomechanics, and perhaps non progression of keratoconus. Therefore, RGP lenses can be regarded safe and appropriate in keratoconic patients.

角膜屈光手术是目前屈光手术的主流术式，随着全飞秒、全激光手术方式的发展，手术变得更加安全精准，不仅角膜创伤小，术后恢复时间也进一步缩短。角膜具有屈光特性和典型的生物软组织力学特性，角膜力学特性不仅参与维持角膜形态，影响角膜手术尤其屈光手术的效果及预后，而且还与部分角膜疾病的发生和发展密切相关。近年来生物力学研究发展迅速，其在眼部疾病的诊疗中发挥着越来越重要的作用。角膜生物力学的变化与术前角膜的形态、不同手术方式的选择、术后角膜厚度的改变等多种因素相关，但手术导致的角膜自身形态改变是不可逆的，若术后角膜生物力学的变化较大，可能会引起医源性角膜扩张、继发性圆锥角膜等并发症的发生。为了规避术后角膜扩张风险和指导个性化的术式选择，了解角膜生物力学特性的影响至关重要。文章对角膜的基础结构、角膜生物力学特性、生物力学测量方法和不同术式及不同角膜瓣厚度术后生物力学变化的研究进展进行综述，为近视患者的个性化精准治疗提供理论指导。

Corneal refractive surgery is currently main stream of refractive surgery. With the development of femtosecond and laser surgery, the surgery has become safer and more accurate, resulting in less corneal trauma and a shorter postoperative recovery time. In recent years, biomechanics research has rapidly progressed, and its clinical application has gradually increased. The cornea not only possesses refractive properties but also exhibits typical biological soft tissue mechanical properties. Corneal mechanical properties not only play a role in maintaining corneal morphology but also influence the outcome and prognosis of corneal surgery, especially refractive surgery, and are closely related to the occurrence and development of some corneal diseases. Corneal refractive surgery involves cutting the cornea according to the patient's diopter, which disrupts the integrity of the cornea and inevitably affects its biomechanical stability. Changes in corneal biomechanics are associated with various factors, such as preoperative corneal morphology, the selection of different surgical methods, and postoperative changes in corneal thickness. However, the self-morphology changes caused by surgery are irreversible. If the postoperative changes in corneal biomechanics are significant, it may lead to complications such as postoperative corneal dilation and secondary keratoconus. To avoid postoperative iatrogenic corneal dilation and guide personalized surgical choice, it is crucial to understand the limits of influence of corneal biomechanical properties. This article reviews the research progress regarding corneal biomechanical properties and changes associated with corneal refractive surgery.

随着科学技术的提高、手术方式的改进，角膜屈光手术成为治疗近视的主要方式。角膜屈光手术后角膜形态及生物力学的变化对于尽早发现术后相关并发症及术后长期稳定性具有重要意义，不同的术式及术后不同的恢复阶段角膜表面非球面参数及生物力学指标的变化存在一定差异，明确其变化的原因及机制可对临床研究提供一定的参考。

With the improvement of science and technology and the improvement of surgical methods, corneal refractive surgery has become the main way to treat myopia. The changes of corneal morphology and biomechanics after corneal refractive surgery are of great significance for early detection of postoperative complications and also affect the long-term stability after corneal refractive surgery. There are some differences in the changes of aspheric parameters and biomechanical properties in different surgical procedures and different postoperative recovery stages. Clarifying the reasons and mechanisms of these changes can provide some reference for clinical research.