Relationship between Central Corneal Thickness and Hypotony Maculopathy after Trabeculectomy

Abstract

To study the relationship of central corneal thickness and other factors and the development of hypotony maculopathy (HM). Prospective case-control study. Thirteen patients with HM and 25 controls with hypotony (defined as intraocular pressure [IOP] of 6 mmHg or less) without signs of maculopathy after trabeculectomy or combined phacotrabeculectomy. Information from consecutive patients and controls was collected in a prospective manner. Factors associated with presence of HM were investigated by comparing the findings in the 2 groups in univariate and multivariate analysis. The following factors were investigated: demographic factors (age and gender), presenting IOP, central corneal thickness (CCT), refractive error, type of glaucoma surgery, and presence of choroidal effusion, among others. Among the variables evaluated, a significant difference between the 2 groups was observed in the age of the patients (patients with HM being significantly younger: 59+/-20 years vs. 73+/-9 years; P = 0.015) and in CCT (eyes with HM having significantly thicker cornea: 553+/-51 microm vs. 506+/-34 microm; P = 0.004). Both predictive factors (younger age and thicker CCT) persisted as significant in a multivariate logistic regression analysis. The measured IOP during hypotony was similar between eyes with HM and hypotony alone (4.7+/-3.2 mmHg and 3.9+/-1.6 mmHg, respectively; P = 0.649). No differences in gender, type of surgery, presence of choroidal detachment, lens status, or degree of myopia were observed between the 2 groups. This study shows that patients with hypotony and thinner central corneas have a lower risk of experiencing maculopathy. This association may result from the influence of CCT on applanation tonometry, although we can not rule out that CCT is related to the development of HM by other mechanisms. This study suggests that CCT should be taken in consideration when setting a target pressure after glaucoma filtering surgery, particularly if the target IOP is low.