Predictive Value of Conjunctival Cytology in Bleb-dependent Glaucoma Surgery

Abstract

Purpose: Metaplasia, chronic inflammation and subconjunctival fibrosis favor failure of bleb-dependent glaucoma surgery. The aim of the study is to identify the patients at a higher risk of post-surgical failure.

Materials and methods: Prospective, open study, performed in the Glaucoma Unit of the Hospital Universitario Virgen Macarena, from April to November 2021, with a minimum follow-up of one year. 38 eyes with ocular hypertension or chronic open-angle glaucoma were included. All patients underwent preoperative conjunctival sampling in the operating room, under topical or locoregional anesthesia.

Parameters measured: Sex, age, and laterality; number, type and mean time of preoperative drugs use; type of surgery performed; cytology results and degree of metaplasia; percentage of patients in whom the bleb was closed. Evaluation of potential correlation between bleb closure and any of the other variables.

Results: 20 women and 18 men participated, with a mean age of 67 years. The mean number of preoperative hypotensive drugs was 2.7. The mean time of use was 90,97 +/- 48,97 months. Most patients had normal cytology, 8% had inflammatory infiltrate and 21% had squamous metaplasia. When relating bleb failure and cytology, we saw that in those who failed surgery, more than half had cytological alterations. A multiple logistic regression was performed, in which we observed that there was statistically significant association (p = .02) between surgical closure and altered cytology.

Conclusions: According to these results, preoperative conjunctival cytology can help predict those cases with a lower probability of surgical success.

Keywords: Bleb failure; conjunctival cytology; conjunctival squamous metaplasia; filtering surgery; glaucoma.