Factors related to hypertensive phase after glaucoma drainage device implantation

BACKGROUND: The aim of the study was to evaluate factors related to hypertensive phase (HP) after glaucoma drainage device (GDD) implantation. PATIENTS AND METHODS: Retrospective charts review of glaucoma patients who underwent GDD implantation and completed 12 months of follow-up at King Chulalongkorn Memorial Hospital since 2004 was performed. Patients were divided into two groups according to the presence or absence of HP. The data were analyzed for factors associated with HP. The surgical outcomes including surgical failure, post-operative visual acuity (VA), post-operative number of medications, post-operative intraocular pressure (IOP), and post-operative complication were compared between the two groups. RESULTS: Seventy-two patients were included. Most were diagnosed with secondary glaucoma (N=51, 70.8%), and Baerveldt was the most implanted GDD (N=49, 68.1%). Mean ± SD of IOP was significantly lower: 27.1±9.6 mmHg at pre-operation and 13.7±59 mmHg at 12-month follow-up (p<0.001). HP was identified in 38/72 patients (52.8%, 95% CI 40.7–64.7). Risk factor of HP was pre-operative VA equal or better than 20/70 (p=0.021, OR 7.5; 95% CI 1.4–41.4). Presence of underlying heart disease (patients in this group had taken anti-platelets) was found as a protective factor for HP (p=0.027, OR 0.06; 95% CI 0.00–0.72). It was speculated that the anti-inflammatory effect of the anti-platelets, particularly aspirin, may be responsible for controlling inflammation and retarding fibrosis formation around drainage implants. Failure rate at 12 months was 24/72 (33%). There was no difference in all surgical outcomes between the two groups. Survival analysis also showed no significant difference between HP and non-HP group. CONCLUSION: HP commonly occurred after GDD implantation. Pre-operative VA was a risk factor for the development of HP, whereas presence of underlying heart disease was a protective factor. No association between HP and surgical outcomes was identified.