Outcomes of trabeculectomy with polyvinylpyrrolidone collagen versus mitomycin in primary open angle glaucoma. 36-month follow-up.

PURPOSE: Describe and compare the effects of intraoperative application of Polyvinylpyrrolidone Collagen (PVP) versus Mitomycin C (MMC) on the pattern of change in mean IOP reduction and mean number of medications over 36-months follow-up in patients with primary open angle glaucoma (POAG) undergoing trabeculectomy.

METHODS

Prospective, randomized, comparative study. Twenty-six eyes of 26 patients with POAG and no previous incisional glaucoma surgery underwent trabeculectomy and were randomized to PVP or MMC and completed a 36-month follow-up. Main outcome measures were IOP and number of glaucoma medications. Multivariate longitudinal analysis was performed by fitting a linear trend model adjusting for baseline response for the IOP outcome and a log-linear regression model with within-subject associations for the number of hypotensive medications outcome. Sensitivity analysis was performed to assess lower and higher order polynomial trends over time in IOP.

RESULTS

The univariate analysis revealed that the mean IOP reduction from baseline to 36 months was 7.62mmHg (3.05; 12.18) in the MMC group and 8.15mmHg (-0.64; 16.95) in the PVP group. Mean percentage IOP reduction from baseline was 37.09% (15.93; 58.17) and 36.08% (5.16; 67.20) in the PVP group. Mean change in number of medications from baseline to 36 months was -0.92 medications (-3.38; +1.54) for the MMC group and -1 medication (-3.12; +1.12) for the PVP group. Both groups had a statistically significant decline in mean IOP over the follow-up period (p<0.001) but there was no discernible difference between the two exposure groups in the rate of change in IOP (p=0.5975). Sensitivity analysis showed that a linear trend model is adequate to describe the IOP reduction over the follow-up period. Both groups had a statistically significant change in the number of hypotensive medications used between baseline and month 36 (p<0.05) but there was no discernible difference between exposure groups (p=0.2917). Both the PVP and MMC groups showed an initial reduction in number of medications until month 12 and a relatively linear increase towards month 36. A longer follow-up may be warranted to reveal differences in the number of medications between the two exposure groups. Postoperative complications were less frequent in the PVP group.

CONCLUSIONS

The use of PVP during trabeculectomy achieves and maintains a statistically significant IOP reduction from baseline to 36 months and decreases the number of glaucoma medications. Secondary outcome measures showed a lower incidence of adverse events in the PVP group.