The role of Near-infrared reflectance imaging in the evaluation of subclinical choroidal abnormalities in neurofibromatosis
Yousef Alizadeh1 , Maryam Dourandeesh1 *
- Eye Research Center, Department of Eye, Amiralmomenin Hospital, School of Medicine, Guilan University of Medical Sciences, Rasht, Iran.
Abstract: Neurofibromatosis type I is an autosomal dominant disease caused by deletion or mutation of the neurofibromin gene located on chromosome 17p11.2 with an average prevalence of 1:4000 and an estimated incidence of 1:3000 (1,2) ocular manifestations of this disease include iris Lisch nodules, optic gliomas, orbital and eyelid neurofibromas, eyelid café-au-lait spots, congenital absence of the greater wing of sphenoid bone, congenital glaucoma and choroidal abnormalities such as choroidal nevi.(2) Imaging techniques such as Indocyanine green angiography, spectral-domain optical coherence tomography (SD-OCT) and confocal near-infrared reflectance (NIR) imaging can be used to detect choroidal abnormalities, undetectable with conventional ophthalmoscopic examination or in fluorescein angiograms.(3)
Here, we present subclinical choroidal involvement in a known case of neurofibromatosis type I.
Methods: A 33-year-old female, known case of Neurofibromatosis type I, referred to our clinic for a routine eye examination. Her ocular and drug histories were unremarkable. The best-corrected visual acuity (BCVA) of both eye was 20/20.Slit-lamp examination, fundus examination and IOP of both eyes were normal (figure 1). Near-infrared reflectance (NIA) of both eye revealed multiple well-defined, bright, patchy lesions (figure 2). The corresponding enhanced depth spectral-domain optical coherence tomography (EDI SD-OCT) showed hyperreflective lesions within the choroid ( choroidal nodule) (figure 3)
Results: Figure 1-3
Conclusion: NIR imaging is used as a non-invasive, in vivo, non-contact, fast, sensitive, and reproducible examination to detect choroidal nodules in patients with NF-1 especially when fundus examination seems normal. It can record pathologic features underneath the retinal pigment epithelium because of the good transmission of long-wavelength light through melanin and lipofuscin.(3)
Choroidal nodules , also known as choroidal neurofibromatosis, can be seen in up to 82% of the NF-1 patients. These ovoid bodies are consisting of proliferating neoplastic Schwann cells arranged in concentric rings around axons. They represent as hyperreflective rounded or patchy nodules in NIR imaging which are associated with hyperreflective signals in choroidal tissue on EDI SD-OCT. The high prevalence of these nodules in patients with NF-1 has prompted the researchers to add it to the actual diagnostic criteria for NF1.(4,5)
