Retinal microvascular abnormalities overlying choroidal nodules in neurofibromatosis type 1

Background: Neurofibromatosis type 1 (NF1) is an autosomal dominant disorder involving aberrant proliferation of multiple tissues of neural crest origin. Retinal vascular alterations in NF1 have rarely been reported in the literature and their nature is not clear. This study describes distinctive retinal microvascular alterations and their relationship to choroidal nodules in patients with neurofibromatosis type 1. Methods: This was a retrospective study where records of seventeen consecutive patients with diagnosis of NF1, presenting Lisch nodules and choroidal alterations, and 17 age and gender-matched healthy control patients were evaluated. Fundus photographs, near infrared reflectance and enhanced depth imaging - optical coherence tomography images were reviewed. Retinal microvascular abnormalities and choroidal and retinal alterations in proximity of the retinal microvacular alterations were carefully noted. Results: 6 patients (35%) presented distinctive microvascular abnormalities. These consisted of small, tortuous vessels with a spiral or corckscrew aspect. They were second or third order, small tributaries of the superior or inferior temporal vein. These vessels were all located overlying choroidal alterations as observed with near infrared reflectance. Enhanced depth imaging - optical coherence tomography showed alteration of choroidal vasculature due to the presence of choroidal nodules but otherwise retinal and choroidal cross-sections were unremarkable for morphology. Conclusions: Retinal microvascular alterations overlying choroidal nodules in patients with NF1 can be considered another distinctive characteristic of the disease. Although the nature of these alterations is not clear, the authors speculate that functional disorders of vasomotor nerve cells, which originate in the embryonal neural crest can lead to their formation.