Conjunctival vasculature patterns influencing the filtering bleb shape following trabeculectomy with limbal-based conjunctival flaps

Purpose To investigate the correlation between conjunctival vasculature factors and two types of functional bleb shape, cystic and diffuse, formed after trabeculectomy with limbal-based conjunctival flaps. Methods Eighty-five eyes of glaucoma patients were consecutively enrolled. After 6 months, functioning blebs were classified as either cystic or diffuse. For each bleb type, the presence of neovascularized vessels in the dissected area (NVc) or the nondissected area (NVi), an avascular area (AVA), or a posterior tarsal artery (PTA) feeding the conjunctiva was analyzed. Results In 62 eyes with functioning blebs, there were 54 cystic and eight diffuse blebs. AVA was present in 96.3% of the cystic and 25.0% of the diffuse blebs. NVc was present in 100% of the cystic and 62.5% of the diffuse blebs, and NVi in 96.3% of the cystic and 12.5% of the diffuse blebs. A PTA was present in 87.5% of the diffuse blebs, but in only 3.7% of the cystic blebs. AVA, NVi, and NVc were significantly more frequent in cystic blebs, whereas a PTA was more frequent in diffuse blebs. The presence of a PTA in the blebs was negatively related to the presence of AVA, NVc, or NVi. Conclusions Avoidance of damage to the PTA during conjunctival dissection might facilitate the formation of a diffuse filtration bleb. The conjunctival vasculature should be considered to avoid cystic avascular bleb formation in trabeculectomy with limbal-based flaps.