Scheimpflug Corneal Densitometry Changes After Trabeculectomy

Purpose: To study the possible changes in Scheimpflug corneal densitometry 6 months after mitomycin C-augmented trabeculectomy and to compare these measurements with healthy controls. Methods: Corneal densitometry was monitored with the Pentacam HR3 before and 6 months after first-time uncomplicated mitomycin C-augmented trabeculectomy in 42 eyes of 42 white patients with open-angle glaucoma and in 22 healthy age-matched controls. Preoperative intraocular pressure (IOP), central corneal thickness, known duration of the disease, gender, the type and number of substances, applications and amount of benzalkonium chloride per day, and postoperative topical cortisone use were tested for possible correlations in the trabeculectomy group. Results: There was a statistically significant reduction of mean diurnal IOP from 19.0 +/- 7.7 to 11.1 +/- 7.7 mm Hg (P = 0.003) and the amount of pressure-lowering substances from 3.7 +/- 1.0 to 0.1 +/- 0.5 (P < 0.001). Densitometry measurements decreased in the entire cornea from 25.5 +/- 5.7 to 23.1 +/- 5.8 grayscale units (P = 0.001) with emphasis in the anterior layer. They returned close to normal 6 months after trabeculectomy and were not statistically significantly different compared with a healthy control group (22.8 +/- 3.4 grayscale unit; P = 0.824). No correlations could be found with these observations and possible causing factors studied. Conclusions: Corneal densitometry, an objective and sensitive measure of corneal transparency, returned close to normal 6 months after trabeculectomy. Although the observations cannot be associated with any causing factor in this study, the significant IOP reduction and the nearly complete cessation of topical antiglaucomatous substances including benzalkonium chloride seem to be the most plausible reasons for this finding.