Abstract
BACKGROUND: Vitreous cysts are rare clinical findings and seldom cause visual disturbance. They are generally classified as congenital or acquired and are considered idiopathic when the etiology can not be determined. A previous electron microscopic observation on an idiopathic pigmented vitreous cyst has confirmed its pigment epithelial origin. However, the specific kind of pigment epithelium involved remains unclear. CASE PRESENTATION: A 39-year-old female presented with a round-shaped floater causing frequent visual disturbance in the left eye. A pigmented, non lobulated and freely mobile vitreous cyst was observed in the anterior vitreous by slit lamp examination and anterior segment optical coherence tomography. The pigment clumps on the cyst wall showed no autofluorescence. No persistent hyaloid artery or connection between the cyst and ocular structures was found by fundus fluorescein angiography and B-scan ultrasound. Serum tests for cysticercoids, sparganosis and toxoplasma were negative. A diagnosis of idiopathic vitreous cyst was made and no intervention was given. The cyst sank to the inferior part of the vitreous and the patient felt less visual disturbance during one-year follow-up. CONCLUSIONS: We described the features of a pigmented vitreous cyst revealed by autofluorescence and anterior segment optical coherence tomography for the first time. The intact retina, the absence of lipofuscin of the cyst and its location in the anterior vitreous led to the hypothesis that the cyst may originate from the ciliary pigment epithelium rather than the retinal pigment epithelium.