Shen Steven R, Fleming Gloria P, Jain Shelly Gupta, Roberts Cynthia J
College of Medicine, The Ohio State University, Columbus, OH, USA.
Department of Ophthalmology and Visual Sciences, The Ohio State University, Columbus, OH, USA.
Curr Eye Res. 2023 Feb;48(2):172-181. doi: 10.1080/02713683.2022.2099903. Epub 2022 Aug 5.
The mechanism of action underlying prostaglandin analog (PGA) therapy involves changes in the expression of different metalloproteases to increase permeability of the sclera and allow increased aqueous humor outflow through this alternative drainage pathway. This alteration of structure impacts cornea/scleral biomechanics and may introduce artifact into the measurement of intraocular pressure (IOP) in the clinical setting.
A literature search reviewing the impact of PGA therapy on corneal and scleral biomechanics was conducted including basic studies, clinical studies with treatment naïve patients, and a clinical study examining the cessation of PGA therapy. Additional literature including engineering texts was added for greater clarity of the concepts underlying ocular biomechanics.
One study with an animal model reported significant corneal stiffening with PGA treatment. Most longitudinal clinical studies examining the effects of initiation of PGA therapy in PGA naïve subjects failed to report biomechanical parameters associated with stiffness using the Corvis ST and only included those parameters strongly influenced by IOP. One study reported a significant reduction in scleral stiffness with IOP as a co-variate, highlighting the need to account for the effects of IOP lowering when assessing clinical biomechanics. The report of cessation of PGA therapy on corneal biomechanics showed no change in corneal compensated IOP after 6 weeks, raising the question of reversibility of the PGA-induced structural alteration.
Given that the findings in several clinical studies may merely reflect a reduction in IOP, further studies are warranted using Corvis ST parameters associated with corneal and scleral stiffness. The gold standard for IOP measurement in the clinical setting is Goldmann applanation tonometry, a technique previously shown to be affected by corneal stiffness. Since PGA therapy has been reported to alter not only scleral biomechanics, but also corneal biomechanics, it is essential to consider alternative tonometry technologies in the clinic.
前列腺素类似物（PGA）治疗的作用机制涉及不同金属蛋白酶表达的改变，以增加巩膜的通透性，并使房水通过这一替代引流途径增加流出量。这种结构改变会影响角膜/巩膜生物力学，并可能在临床环境中给眼压（IOP）测量带来假象。
进行了一项文献检索，回顾了PGA治疗对角膜和巩膜生物力学的影响，包括基础研究、对未接受过治疗的患者的临床研究，以及一项关于停止PGA治疗的临床研究。还添加了包括工程学文本在内的其他文献，以更清晰地阐明眼部生物力学的基本概念。
一项动物模型研究报告称，PGA治疗后角膜显著变硬。大多数纵向临床研究在未接受过PGA治疗的受试者中研究PGA治疗起始的效果时，未能使用Corvis ST报告与硬度相关的生物力学参数，仅纳入了那些受IOP强烈影响的参数。一项研究报告称，以IOP作为协变量时，巩膜硬度显著降低，这突出了在评估临床生物力学时考虑降低IOP的影响的必要性。关于停止PGA治疗对角膜生物力学影响的报告显示，6周后角膜补偿眼压没有变化，这引发了PGA诱导的结构改变是否可逆的问题。
鉴于几项临床研究的结果可能仅仅反映了IOP的降低，有必要使用与角膜和巩膜硬度相关的Corvis ST参数进行进一步研究。临床环境中IOP测量的金标准是Goldmann压平眼压测量法，这是一种先前已证明受角膜硬度影响的技术。由于据报道PGA治疗不仅会改变巩膜生物力学，还会改变角膜生物力学，因此在临床中考虑使用替代眼压测量技术至关重要。
