Incidence of, risk factors for, and combined mechanism of late-onset open-angle glaucoma after vitrectomy.

PURPOSE

To estimate the incidence of and identify the risk factors for late-onset open-angle glaucoma (OAG) after uncomplicated pars plana vitrectomy (PPV).

METHODS

All patients who underwent PPV at the Edward Harkness Eye Institute between January 1998 and January 2004 had at least 6 months of follow-up and did not have preexisting glaucoma or reason for secondary development of glaucoma were included. Retrospective cohort and matched case-control study designs were used.

RESULTS

Of 285 vitrectomized eyes that met enrollment criteria, 11.6% (n = 33) developed glaucoma after vitrectomy. In the matched case-control analysis, the only variable that had a statistically significant association with the development of OAG was cataract extraction (CE), as compared with phakic status at the last follow-up (odds ratio = 16.4; 95% confidence interval, 2.1-127.4; P = 0.007). There was no difference in OAG development between eyes that had CE before or at the time of PPV and those that had it after PPV. The overall incidence of OAG development after PPV among all eyes, phakic eyes, and nonphakic eyes was 11.6%, 1.4%, and 15.0%, respectively. The difference in incidence between phakic and nonphakic eyes was statistically significant (P = 0.001).

CONCLUSION

Lens extraction is a strong risk factor for the development of late-onset OAG after uncomplicated PPV. While the overall incidence of OAG development after PPV is substantial, it is more so among eyes that have had CE. The absence of substantial OAG incidence in phakic patients points toward a combined mechanism for late-onset post-PPV OAG involving PPV and CE at any time. Preoperative PPV counseling should include the risk of glaucoma development in addition to cataract development and the connection between the two. Patients who have undergone PPV, and especially those who also had CE in the same eye, should be carefully monitored for glaucoma.