High-frequency ultrasound biomicroscopy (UBM) has been proven useful in the diagnosis and management of anterior segment pathology.1,2 A case of probable arteriovenous malformation (AVM) of the ciliary body that was imaged with UBM is described. Case reportA 33-year-old male presented with abnormal redness in the left eye associated with symptoms of itch and discomfort for 5 years. He was most disturbed by the cosmetic appearance of persistent dilated vessels ( Figure 1). There was no history of orbital trauma or family history of vascular disorders. Visual acuity (VA) unaided was 20/20 in both eyes. Eye position was neutral with no proptosis. Pupils were isocoric and round, with full extraocular movements. Slit-lamp examination revealed dilated tortuous conjunctival and episcleral vessels in the nasal aspect of the left eye. Intraocular pressures were normal. There was no abnormal iris pigmentation or mass. Fundus examination showed normal retinal vessels. A provisional diagnosis of AVM over the left nasal conjunctiva was made and was initially managed expectantly.UBM revealed hypoechoic 'sheets' and tubular structures (Figure 2, arrows) in the ciliary body corresponding to the position of the overlying dilated conjunctival and episcleral vessels and with possible communications between the deep and superficial portions. These hypoechoic areas were shown to communicate. The iris configuration was normal. There was no ciliary body mass or swelling and the ciliary body processes appeared normal. The patient elected for surgical excision for cosmesis, and this was performed. At the time of surgery, the dilated, tortuous vessels were cauterised and excised without difficulty and a free conjunctival autograft was obtained from the superotemporal bulbar conjunctiva and sutured over the nasal defect. The eye was treated with topical antibiotics and steroids postoperatively.VA was unchanged postoperatively. The patient was happy with the cosmetic result and no recurrence of dilated vessels occurred. UBM repeated 2 weeks postoperatively showed no change in the extent or configuration of the ciliary body hypoechoic areas and no ciliary body swelling or mass. Comment