School of Biomedical Engineering, Shanghai Jiao Tong University, 800 Dongchuan Rd., Shanghai 200240, China.
Exp Eye Res. 2011 Oct;93(4):541-7. doi: 10.1016/j.exer.2011.06.021. Epub 2011 Jul 13.
Collagen crosslinking induced by riboflavin and ultraviolet A irradiation (UVAR) has recently been introduced as a clinical treatment to halt or reverse the progression of keratoconus. We investigated changes in corneal sensitivity and nerve morphology as part of a comprehensive safety evaluation of this treatment. Fifty-four New Zealand white rabbits were divided into three experimental groups: UVAR with deepithelialization, UVAR without deepithelialization, and deepithelialization alone. Corneal sensitivity was measured with a Cochet-Bonnet esthesiometer before treatment and 3, 7, 14, 30, 90, and 180 days after treatment. Corneal nerve morphology was evaluated using acetylcholinesterase histochemistry staining. We found that corneal sensitivity in the center of the treated area was significantly reduced 3 days after UVAR with deepithelialization treatment compared with the corneal sensitivity of the control eye but gradually recovered to normal levels at 90 days. Corneal sensitivity after deepithelialization treatment was significantly lower than control corneal sensitivity at 3 days but was significantly higher after 30 days of recovery compared with the corneal sensitivity after UVAR with deepithelialization. Corneal sensitivity after UVAR without deepithelialization treatment had significantly decreased at 7 days compared with control corneal sensitivity but was not significantly different from control values at other measurement times. In parallel with these functional alterations, corneal nerve degeneration was visible in the treatment area by 3 days; by 7 days there was a significant decrease in nerve density. Corneal nerve sprouts were identified from neighboring non-injured nerve fibers 7 days after treatment; by 90 days, excessively regenerating nerves were observed throughout the anterior stroma. The density of corneal nerve fibers appeared normal by 180 days. Ultraviolet A/riboflavin with deepithelialization treatment resulted in corneal nerve fiber damage and subsequent regeneration in the treatment area, simultaneously accompanied by the reduction and recovery of corneal sensitivity.
核黄素和紫外线 A 照射（UVAR）诱导的胶原交联最近被引入临床治疗，以阻止或逆转圆锥角膜的进展。我们研究了角膜敏感性和神经形态的变化，作为这种治疗全面安全性评估的一部分。54 只新西兰白兔被分为三组：去上皮化 UVAR、无去上皮化 UVAR 和单独去上皮化。在治疗前和治疗后 3、7、14、30、90 和 180 天，使用 Cochet-Bonnet 触觉计测量角膜敏感性。使用乙酰胆碱酯酶组织化学染色评估角膜神经形态。我们发现，与对照眼相比，去上皮化 UVAR 治疗后 3 天治疗区域中央的角膜敏感性显著降低，但在 90 天逐渐恢复正常水平。去上皮化治疗后的角膜敏感性在 3 天时明显低于对照角膜敏感性，但在 30 天恢复后明显高于去上皮化 UVAR 后的角膜敏感性。无去上皮化 UVAR 治疗后的角膜敏感性在 7 天与对照角膜敏感性相比明显降低，但在其他测量时间与对照值无显著差异。与这些功能改变平行的是，在治疗区域 3 天即可观察到角膜神经变性；在 7 天，神经密度显著降低。在治疗后 7 天，从邻近未受伤的神经纤维中识别出角膜神经芽；在 90 天时，在前基质中观察到过度再生的神经。在 180 天时，角膜神经纤维的密度似乎恢复正常。去上皮化的紫外线 A/核黄素治疗导致治疗区域的角膜神经纤维损伤和随后的再生，同时伴有角膜敏感性的降低和恢复。
