Purpose: To compare intraocular pressure (IOP) control in eyes with or without clear corneal phacoemulsification following trabeculectomy. Methods: The study group included 30 eyes that underwent uneventful clear corneal phacoemulsification and foldable intraocular lens implantation following trabeculectomy without antimetabolites. Thirty eyes that had undergone filtering surgery without cataract extraction were selected as controls. Case and control groups were matched with respect to age, gender, IOP, number of glaucoma medications, glaucoma type (primary open-angle glaucoma/pseudoexfoliative glaucoma), trabeculectomy time and follow-up. Comparisons between the study and control groups (intergroup) and within the same group at different time-points (intragroup)were performed for IOP, glaucoma medications and bleb morphology. Success rates were investigated by Kaplan-Meier survival analysis and the factors influencing final success by logistic regression. Results: Intraocular pressure (p=0.04) and glaucoma medications (p=0.001) increased during an average follow-up of 26.1 ± 9.9 months in both groups. Intragroup differences became statistically significant after the 6- month visit, but intergroup differences remained insignificant. Bleb height decreased significantly following phacoemulsification in the study group (p=0.017). Success rates decreased with time in both groups, with no intergroup difference (p=0.46). The final success rate was negatively correlated with IOP and number of glaucoma medications used at the study entry, while there was a positive correlation between the baseline and final success rates. Conclusion: Trabeculectomy success decreased in a time-dependent manner in eyes with and without subsequent phacoemulsification. Uncomplicated clear corneal phacoemulsification was not found to have any additional unfavorable influence on IOP control in eyes with filtering blebs. Methods: The study group included 30 eyes that underwent uneventful clear corneal phacoemulsification and foldable intraocular pressure (IOP) control in eyes with or without clear corneal phacoemulsification following eyes or with clear corneal phacoemulsification without antimetabolites. Thirty eyes that had undergone filtering surgery without cataract extraction were selected as controls. Case and control groups were matched with respect to age, gender, IOP, number of glaucoma medications, glaucoma type (primary open-angle glaucoma / pseudoexfoliative glaucoma), trabeculectomy time and follow-up. Comparisons between the study and control groups (intergroup) and within the same group at different time-points (intragroup) were performed for IOP, glaucoma medications and bleb morphology. Success rates were investigated by Kaplan-Meier survival analysis and the factors influencing final success by logistic regression. Results: Intraocular pressure (p = 0.04) and glaucoma medications (p = 0.001) increased during an average follow-up of 26.1 ± 9.9 months in both groups. Intragroups became resistance significant after the 6- month visit, but intergroup differences remained insignificant. Success rates decreased with time in both groups, with no intergroup difference (p = 0.46). The final success rate was negatively correlated with IOP and number of glaucoma medications used at the study entry, while there was a positive correlation between the baseline and final success rates. Conclusion: Trabeculectomy success decreased in a time-dependent manner in eyes with and without subsequent phacoemulsification. Uncomplicated clear corneal phacoemulsification was not found to have any additional unfavorable influence on IOP control in eyes with filtering blebs.