Glaucoma control after phacoemulsification in eyes with functioning glaucoma filtration surgeries: trabeculectomies versus glaucoma drainage devices.

PURPOSE

Several studies have demonstrated decompensation of intraocular pressure (IOP) control following phacoemulsification in eyes with a functioning trabeculectomy. Limited evidence base suggests that this effect is minimal in eyes with functioning glaucoma drainage devices (GDD). The aim of this study was to report on glaucoma control after phacoemulsification in eyes with a functioning GDD compared to eyes with a functioning trabeculectomy.

METHODS

Single-centre retrospective comparative study of patients with a functioning non-valved GDD (Baerveldt 350; Johnson & Johnson Surgical Vision) or trabeculectomy undergoing phacoemulsification. Glaucoma outcomes including IOP, cup:disc ratio (CDR), global retinal nerve fibre layer (RNFL) thickness and visual field mean deviation (MD) are reported. Failure was defined as IOP rise > 20% from baseline.

RESULTS

Fifteen eyes with a functioning trabeculectomy and twenty-three eyes with a functioning GDD with 24-month post-phacoemulsification data were identified. Mean IOPs were significantly lower in the trabeculectomy group at month 24 compared to the GDD group, 9.5 and 15.9 mmHg (p = 0.001) respectively. At month 12, there was significant worsening on MD in GDD group compared to trabeculectomy group, - 20.0 dB and - 11.3 dB respectively (p = 0.03). A greater proportion of eyes failed in the GDD group compared to the trabeculectomy group, N = 15 (65%) and n = 7 (47%), p = 0.26.

CONCLUSION

As with functioning trabeculectomies, phacoemulsification should be approached with similar caution in eyes with functioning GDD. An existing GDD is at least as likely to fail following clear corneal phacoemulsification as an existing trabeculectomy and non-augmented GDDs may be at greater risk.