OBJECTIVE: To compare the intraocular pressure control of trabeculectomy with mitomycin-C (Trab MMC) versus glaucoma drainage device (GDD) implantation in glaucoma management after penetrating keratoplasty (PKP).
METHODS: A review of medical records of patients who developed glaucoma after penetrating keratoplasty and underwent either trabeculectomy with mitomycin-C augmentation or glaucoma drainage device implantation between October 2006 to June 2012 at a tertiary referral eye center was done. The following information were obtained for each patient: age, gender, corneal diagnosis before keratoplasty, details of keratoplasty in terms of graft versus donor size, other simultaneous operations, visual acuity (VA), intraocular pressure (IOP), number of glaucoma medications before and after PKP, graft status before glaucoma treatment and at the final visit, type of glaucoma before treatment, and the glaucoma procedure performed and its complications if any. Three primary outcomes were evaluated: graft status, postoperative IOP, and VA. Controlled IOP with or without medications was defined as IOP greater than 6 but less than 20. Paired t-test determined the significant decrease in the mean IOP control and the number of medications before and after keratoplasty. Single-factor analysis of variance (ANOVA) determined if there were significant differences in the mean between the two surgeries. Kaplan-Meier survival analysis compared the surgeries in their effects on graft clarity.
RESULTS: Out of the 222 medical records reviewed, 23 patients met the inclusion criteria. Twelve (52.2%) eyes had clear grafts after glaucoma surgery; 8 (72.7%) in the Trab MMC and 4 (33.3%) in the GDD groups. Twenty-one (91.3%) eyes had controlled IOP; 9 (81.8%) had Trab MMC, 12 had GDD surgeries. There was no difference (p = 0.07) in percentage of patients with controlled IOP between the 2 groups. Mean IOP in the Trab MMC (32.6 ± 4.3 to 15.1 ± 4.0, p = 0.004) and GDD (23.6 ± 4.6 to 12.5 ± 0.8, p = 0.04) groups significantly decreased after the procedures. The decrease in mean IOP was not different (p = 0.55) between the 2 groups. The number of patients with controlled IOP increased significantly (p = 0.02) in the Trab MMC group. There were no differences in the mean number of glaucoma medications between both groups before (p = 0.92) and after (p = 0.18) glaucoma surgery. There was no difference (p = 0.17) in the survival distribution of controlled IOP between the 2 surgeries.
CONCLUSION: Trabeculectomy with mitomycin-C augmentation and glaucoma drainage device implantation are effective methods of controlling IOP post penetrating keratoplasty. There was no difference between the two groups in controlling the IOP and in reducing the number of glaucoma medication postoperatively.