Diagnosis and treatment of spontaneous filtering bleb: A case report

A 72-year-old patient presented with decreased visual acuity and ocular discomfort. The patient had not undergone previous ocular surgery or had a history of ocular trauma. Physical examination revealed decreased intraocular pressure (IOP) (9 mmHg), a subconjunctival filtering bleb, and hypotonic maculopathy. Ultrasound biomicroscopy revealed a fistula between the anterior chamber and the subconjunctival space at Schwalbe's line. The patient presented no findings suggestive of systemic disease or dysmorphic facial features. Surgical closure of the fistula was attempted using multiple transconjunctival 10-0 nylon sutures and staining using trypan blue 0.06%. Although the fistula was not sealed, the bleb became flatter, IOP increased (18 mmHg), and hypotonic maculopathy resolved. Spontaneous formation of subconjunctival filtering blebs is exceedingly rare; most reported cases are associated with concomitant systemic or local disease. Our novel surgical approach successfully treated the hypotony and revealed that intraoperative use of trypan blue 0.06% in phakic patients causes temporary capsular staining.