Mehdizadeh Alireza, Hoseinzadeh Amin, Fazelzadeh Afsoon
Medical Physics Research Center, Shiraz University of Medical Sciences, Iran.
Med Hypotheses. 2007;69(6):1205-7. doi: 10.1016/j.mehy.2006.12.066. Epub 2007 Jun 12.
Glaucoma is the second leading cause of blindness worldwide. It has many risk factors such as age, race, sex, intraocular pressure, optic nerve changes, corneal thickness, refractive error, systemic diseases, family history and trauma. Central corneal thickness plays an important role in risk stratification among patients in whom glaucoma was of concern. Scleral thickness and central corneal thickness have a moderately positive correlation. Stress is responsible for glaucoma and causes deformations of the retinal layers and the consequent high levels of neural tissue strain. Stress and scleral thickness have inverse relation together and since scleral thickness is related to central corneal thickness positively, stress is related to central corneal thickness inversely. Risk of progression of glaucoma damage has an inverse relation with the central corneal thickness. This hypothesis is provable via two ways: (1) Based on formula of stress, when central corneal thickness decreases, the amount of stress increases inversely. This leads to more interruption of retinal layers and consequent higher levels of neural tissue strain that increases the risk of suffering glaucoma. (2) Variations of central corneal thickness lead to misestimation of intraocular pressure with Goldmann applanation tonometry. Underestimation of intraocular pressure may lead to underdiagnosis and consequently undertreatment of glaucoma. In conclusion central corneal thickness is a powerful predictor for risk of progression of glaucoma in population. So it should be added to routine clinical examinations for screening of glaucoma. Our hypothesis answers the question about relationship between increased susceptibility to glaucoma damage in patients with thinner corneas.
青光眼是全球第二大致盲原因。它有许多风险因素，如年龄、种族、性别、眼压、视神经变化、角膜厚度、屈光不正、全身性疾病、家族病史和外伤。在关注青光眼的患者中，中央角膜厚度在风险分层中起着重要作用。巩膜厚度与中央角膜厚度呈中度正相关。压力是青光眼的成因，会导致视网膜层变形以及随之而来的高水平神经组织应变。压力与巩膜厚度呈负相关，且由于巩膜厚度与中央角膜厚度呈正相关，所以压力与中央角膜厚度呈负相关。青光眼损害进展的风险与中央角膜厚度呈负相关。这一假设可通过两种方式得到证实：（1）根据应力公式，当中央角膜厚度减小时，应力大小呈反比增加。这会导致视网膜层更多中断，进而使神经组织应变水平升高，增加患青光眼的风险。（2）中央角膜厚度的变化会导致用Goldmann压平眼压计测量眼压时出现误差。眼压低估可能导致青光眼诊断不足，进而治疗不足。总之，中央角膜厚度是人群中青光眼进展风险的有力预测指标。因此，应将其纳入青光眼筛查的常规临床检查中。我们的假设回答了角膜较薄患者对青光眼损害易感性增加之间关系的问题。
