Objective: To determine the incidence of encapsulated bleb (EB) after filtering surgery, and the risk factors for the development of this complication, especially those related with the surgical procedure.
Methods: Ninety eyes that were submitted to trabeculectomy were prospectively studied. Lens extraction was associated in 56 eyes (62.9%). All patients were followed up for at least 3 months.
Results: There were clinical characteristics of encapsulation in 29 eyes (32.3%) and EB with a peak IOP of 25 mmHg or higher in 14 eyes (15.7%). The incidence of EB formation was 20.5% in men and 11.8% in women (p.044). The incidence of EB was higher in the trabeculectomy group alone (24.2%) than in the group in which it was associated to cataract surgery (10.5%) (p.003). There were clinical characteristics of encapsulation in 40.7% of primary open angle glaucoma (p.041). EB was significantly associated with an increased failure rate (21.4%) when compared to normal blebs (5.55% failure rate) (p<.001).
Conclusions: The encapsulated bleb is significantly more frequent in the male gender and thick conjunctivas and in trabeculectomy alone versus trabeculectomy associated to cataract surgery. It means a significantly greater risk of failure after surgery in the short term.