不同应力水平对幼兔巩膜生物力学特性的影响

Effects of stress level on biomechanical properties of sclera in ped-rabbit

目的了解不同应力水平对幼兔巩膜生物力学特性的影响。方法21d新西兰白兔20只随机平均分为2组。高应力组兔1只眼定期向前房内注入玻璃酸钠注射液造成慢性高眼压模型,对侧眼以平衡盐溶液代替玻璃酸钠注射液作为对照;低应力组1只眼采用巩膜下切除、虹膜大部切除加0.5%噻吗心胺滴眼液点眼的方法造成慢性低眼压模型,对侧眼作为对照。幼兔3个月时测量眼轴长度,摘除双眼行巩膜生物力学指标测定。结果高应力组与低应力组实验眼和对照眼实验后的眼轴长度均较实验前明显延长(P<0.05);而实验后2组实验眼眼轴长度与各自的对照眼的差异均无统计学意义。高应力组实验眼的巩膜生物力学指标与对照眼相比差异无统计学意义;低应力组实验眼与对照眼间的差异、高应力组与低应力组实验眼间的差异有统计学意义(P<0.05);两组对照眼之间差异无统计学意义。结论眼压在(9.83±0.30)～(35.10±2.78)mmHg时对幼兔眼轴发育和巩膜应力的影响不大。巩膜下切除加虹膜部分切除降低幼兔巩膜的承载能力。通过控制眼压改变巩膜的应力水平与近视眼对巩膜的影响机制不同。

Objective To investigate the effects of stress intensity on the biomechanical properties of the sclera of the pedrabbit. Methods Twenty 21-day-old New Zealand white rabbits were randomly divided into 2 groups. The one eye of each rabbit was chosen as experimental eye and another one was as control. Intraocular hypertension was induced through injection of Sodium Hyaluronatc into anterior chamber and balanced salt solution was used in control eye in group 1. Chronic intraocular hypotension model was created using sclerectomy, and the combination of part of iridotomy and topical administration of 0. 5% Timolol eye drops was applied in another group. Ocular axis length was measured at 3-month old of rabbits. Eyeballs of rabbits were enucleated and the biomechanical properties of sclera were analyzed. Results The ocular axis length was significantly increased after intraocular pressure manipulation in intraocular hypertension group and ocular hypotension group（ P 〈0. 05 ）. In intraocular hypertension group, the axis length of experimental eye was （ 15.09 ±0. 36） mm, and that in the control group was （ 15. 01 ± 0. 56） mm （ P 〉 0. 05 ）. In ocular hypotension group,axis length of experimental eye was （ 15.41 ± 1. 19） mm and （ 15.40 ±1.02） mm in control group （P 〉 0. 05 ）. In intraocular hypertension group, the variable value was （6.06 ×10^- 5 ± 5.57 × 10^- 6 ） mL/mmH2O in experimental eye and （6. 07 × 10^-5 ±4. 13 × 10^-6） in control eye（ P 〉 0. 05 ） ;while that in ocular hypotension group was（7.04 × 10^-5±9.71 × 10^-6） mL/mmH2O and （6. 59 × 10^-5 ± 1.28 × 10^-5 ） in experimental eye and control eye respectively （ P 〈 0. 05 ）. There was significant difference between 2 experimental groups （ P 〈 0. 05 ）. Conclusion The intraocular pressure ranged from （9. 83 ×0. 30） and （35. 10 ± 2.78） mmHg has little impact on ocular axis and transformation and carrying capacity of sclera of younger rabbit. The regulation of sclera stress intensity through controlling intraocular pressure is a passive effect,and therefore has completely different mechanism from the initiative influence of myopic eyes on sclera.