Congenital isolated idiopathic episcleral arteriovenous malformation.

Purpose: To report the occurrence of an episcleral AVM and to discuss the gravity as well as management of dilated tortuous episcleral vasculature.

Observation: A 16-year-old Asian male presented with redness in the left eye since birth and a history of gradual painless progressive increase in size since the past two years, causing a cosmetic concern for the patient. There was no history of any diminution of vision, diplopia, headache, trauma or any similar lesions anywhere in the body.On examination, unaided visual acuity (UCVA) was 6/6 Snellen in both eyes. Hirschberg's reflex was central and extraocular movements were full and free in both the eyes.On slit-lamp examination, dilated tortuous episcleral vessels were found in the temporal aspect of the palpebral aperture, shaped like a single continuous vascular frond, vertically measuring 10-11mm in extent and horizontally commencing 6mm from the temporal limbus but the posterior limit could not be discernible. The episcleral plane was freely mobile from the overlying conjunctiva and underlying sclera. The dilated episcleral vasculature remained unchanged on Valsalava maneuver and on bending forward.Intraocular pressure was 14 mmHg by Goldmann's appalanation tonometer in both eyes. Iris was normal in configuration and gonioscopy revealed open angles without any evidence of any neovascularisation in both eyes. Fundus examination was unremarkable.USG B-scan was grossly normal. MR Angiography of head and orbit with using thin high-resolution cuts (1mm using 3T machine) was done and was later followed up with a Contrast Enhanced MRI. Both imaging studies revealed an isolated episcleral AVM with a possible feeder vessel from the anterior ciliary artery to the lateral rectus and without any intraorbital or intracranial lesion.A diagnosis of isolated episcleral AVM was made. The episcleral plane was dissected and dilated tortuous vessels were excised. After cautery, conjunctival autograft was obtained from the fellow-eye was used to cover the defect. Histopathological examination revealed both thick and thin walled vessels of varying calibre corresponding to arteries and veins confirming the diagnosis of isolated episcleral AVM. Ref. Fig. 2. No recurrence has been observed over a follow-up period of 1 year.

Conclusion: AND IMPORTANCE: Isolated idiopathic episcleral AVM should be a diagnosis of exclusion. A thorough systemic and ophthalmological evaluation including a glaucoma workup is necessary for both diagnosis and management. UBM and MRI/MRA may be required in select cases to rule out any associations or complications. Management includes observation, embolization and excision.