Morphologic and vasculature features of the choroid and associated choroid-retinal thickness alterations in neurofibromatosis type 1.

Background/aims: A normal structural and functional choroid is essential in supplying blood flow to the retina. Neurofibromatosis type 1 (NF1) is a neurocristopathy where the choroid is altered due to the presence of nodules. The present transversal study was conducted to examine choroidal nodules and their effect on choroidal and retinal thickness in NF1 patients.

Methods: Near-infrared reflectance and optical coherence tomography with enhanced depth imaging were used to evaluate choroidal morphology and vasculature in 19 patients with NF1 and 19 healthy, age-matched control subjects. Choroidal thickness, neuroepithelium thickness, photoreceptors together with retinal pigment epithelium (RPE) thickness and outer nuclear layer (ONL) thickness were measured at the fovea and 1000 μm nasal, temporal, superior and inferior to the fovea in NF1 patients and control subjects. Choroidal and neuroepithelium thickness were assessed overlying and adjacent to nodules in NF1 patients.

Results: Choroidal nodules were classified as 'dome-shaped' or 'placcoid' subtypes in 17 patients. Small and medium calibre choroidal vessels were observed above dome-shaped nodules where choroidal thickness was significantly reduced. There was a statistically significant reduction in mean choroidal thickness (p=0.013) in NF1 patients with respect to control subjects. The neuroepithelium, photoreceptors together with RPE and ONL had a statistically significant reduction in mean thickness in NF1 patients (p<0.001, p<0.001, p=0.012, respectively).

Conclusions: In NF1, there are dome-shaped and placcoid choroidal nodules which alter choroidal morphology and thickness. There is reduction in mean choroid thickness with generalised thinning of the neuroepithelium, photoreceptors together with RPE and ONL in NF1 patients.