[Risk factors for trabeculectomy failure].

BACKGROUND

Trabeculectomy is today the filtering procedure of choice, because complications are rare and success-rates high. A modification of our technique (fornix-based conjunctival flap closed by a running suture) introduced 3 years ago, has lead us to this retrospective assessment of complications and success-rates. Some of the risk factors for failure are known, others however remain obscure. This retrospective series was also used to further identify some of these risk factors for trabeculectomy failure.

PATIENTS AND METHODS

All 388 trabeculectomies performed between January 1992 and June 1994 at our hospital were included in the study. Important pre- and postoperative data were retrospectively assessed from patients case notes, with a special interest in the course of post-operative intra-ocular pressure (IOP). Two major groups were differentiated: Those with open-angle glaucoma (OAG) (i.e. primary open-angle glaucoma (POAG), pseudoexfoliation glaucoma (PEX) and pigment dispersion syndrome (PDS)), and other various glaucoma diagnoses. Risk factors were assessed using Cox-proportional hazard model adopting three different criteria for success.

RESULTS

The best success-rate after 12 months of follow-up had patients with narrow angle glaucoma (93.1%)(at least those suitable for filtering surgery), followed by patients with POAG (92.8%), 2 degrees open-angle glaucoma (81.8%), aphakic (75%), juvenile (70.6%) and PDS (52.9%). Pseudophakia and development of an encapsulated bleb (Tenon' cyst) were identified as significant (p < 0.05) risk factors for failure. In addition, YAG-Laser Iridotomy in OAG-group and Aphakia in the group of various glaucoma diagnoses were identified as risk factors for successful post-operative IOP control.

CONCLUSIONS

Filtering surgery (trabeculectomy) is a potent method to reduce IOP. Pseudophakia and an encapsulated bleb are the main risk factors for surgical failure. Because of amazingly high success-rates we tend to perform filtering surgery today earlier than ten years ago, especially as previous long-term topical antiglaucoma treatment may reduce filtering surgery success.