Two cases of spontaneous filtering blebs, one idiopathic and one associated with Terrien marginal degeneration

To report a case of an idiopathic unilateral filtering bleb in an otherwise well patient and a case of bilateral spontaneous filtering blebs in association with Terrien marginal degeneration.

In this retrospective observational study of 2 cases, clinical notes, ultrasound biomicroscopy and gonioscopy images were reviewed.

Case 1: A 32-year-old woman presented with a 1-year history of a gradually growing cyst in her right eye. No changes in vision were reported. The patient had no previous ocular or systemic history, trauma, or surgical interventions. Slit-lamp examination revealed a multilobulated cyst at the supranasal limbus OD. Diagnosis was an idiopathic spontaneous limbal filtering bleb of unclear etiology because there was no inciting event or obvious cause. Case 2: A 31-year-old man, with 2 past episodes of spontaneous filtering bleb development, affecting the left, then the right, eye, presented with his third event in May 2012. The visual acuity was decreased to 20/400 OD. The right eye was hypotonous and ultrasound biomicroscopy confirmed a shallow anterior chamber, a superior peripheral corneal defect, and an echolucent space suggestive of subconjunctival fluid. Limbal thinning was noted bilaterally, consistent with Terrien marginal degeneration.

This is a rare case of an idiopathic filtering bleb occurring in a healthy patient with no precipitating cause, other ocular abnormalities, or physical malformations, and the only reported case of bilateral sequential filtering blebs associated with an atypical presentation of Terrien marginal degeneration.