Microvascular retinal abnormalities, presenting in a corkscrew configuration, have been very recently described in patients with neurofibromatosis type 1 (NF-1). We report one more patient with NF-1 who had distinctive corkscrew retinal vessels superior and inferior to the fovea. This patient further supports the existence of a true association between this recently described retinal finding and NF-1.
A 31-year-old Greek man was referred for a routine ophthalmic examination. He had been diagnosed with neurofibromatosis type 1 (NF-1) according to the criteria established by the National Institutes of Health (1). Best-corrected visual acuity was 20/20 bilaterally. Anterior segment examination revealed multiple Lisch nodules bilaterally. Retinal examination of the OD was unremarkable. Retinal examination of the OS revealed tortuous retinal venules in a corkscrew configuration superior to the fovea, adjacent to which a microvascular collateral-like network was noted. Inferior to the fovea, similar but less prominent tortuous venules were seen (Figs. 1 and 2). No retinal edema was present clinically. The patient refused to undergo fluorescein angiography.
NF-1 is a common genetic disorder resulting in the formation of a variety of benign and malignant tumors (2). It has an autosomal dominant mode of inheritance with 100% penetrance and variable expressivity. The responsible gene has been located on the long arm of chromosome 17 and encodes for a protein termed “neurofibromin,” which appears to be a tumor-suppression protein.
Iris hamartomas, referred to as Lisch nodules, are the most common ocular finding in NF-1. Other ophthalmic manifestations include plexiform neurofibromas of the eyelids, orbital neurofibromas, orbital bone abnormalities, enlarged corneal nerves, congenital glaucoma, and optic pathway gliomas (2).
Findings in the fundus include choroidal hamartomas (present in one-third to one-half of adults with NF-1), retinal astrocytic hamartomas, combined retinal and retinal pigment epithelial hamartomas, and retinal capillary hemangiomas (3).
In 2002, Muci-Mendoza et al. (4) described a novel retinal finding in NF-1, distinctive microvascular abnormalities noted in 12 out of 32 (37.5%) patients. In 10 cases, the anomaly was very subtle, involving a second or third order venule, a tributary of the superior or inferior temporal veins, or, less frequently, the nasal veins. The tortuous vessel had a corkscrew appearance and ended in a minute tuft. In two of the patients, however, more striking abnormalities were observed: a venovenous anastomosis in the nasal retina and an extensive arteriovenous malformation coexisting with an epiretinal membrane. Two of these 12 patients also had choroidal neurofibromas. Fluorescein angiography obtained in half of the cases did not reveal any leakage. The condition did not disturb vision. According to the authors, this finding is a new retinal marker for NF-1.