Primary vitreous cysts.

Objective: To report two cases of vitreous cysts with discussion of their pathophysiology and management. Methods: Clinical examination with fundus photography, ultrasound and optical coherence tomography. Histopathology was performed in the first case. Results: The first case illustrates a pigmented, free-floating cyst, which was removed during a 27-gauge vitrectomy. The histopathology shows a single layer of pigmented epithelium and confirms the previously reported presence of a PAS-positive basement membrane. The second case shows a sessile, non-pigmented cyst associated with significant anisometropia. Conclusion: Primary vitreous cysts are rare and can have a wide range in their clinical aspect. This likely reflects whether they originate either from the pigment epithelium or the primary hyaloidal system. The management of vitreous cysts is mostly conservative, but pars plana vitrectomy can be used safely if the symptoms are debilitating.