Frequency of choroidal abnormalities in neurofibromatosis type 1

Background Choroidal neurofibromatosis is thought to be a rare form of neurofibromatosis that involves the eyes. The development of infrared light examination with a scanning laser ophthalmoscope (SLO) and indocyanine-green fundus angiography has allowed examination of the choroid. We studied choroidal abnormalities in patients with neurofibromatosis 1 and compared their frequency with that of other ocular abnormalities. Methods We examined 33 eyes of 17 consecutive patients diagnosed with neurofibromatosis 1 by conventional ophthalmoscopy and by non-invasive infrared monochromatic light with confocal SLO. 76 eyes of 39 age-matched controls were examined similarly by confocal SLO. 21 digital fluorescein and indocyanine-green angiographies were obtained from 11 adult patients, and 77 angiograms were obtained from age-matched controls. Findings Infrared monochromatic light examination by confocal SLO showed bright multiple patchy regions at and around the entire posterior pole of all 33 eyes examined. All bright patchy regions seen in adult patients corresponded to hypofluorescent areas on their indocyanine-green angiograms. However, no abnormalities were noted in any patient at corresponding areas under conventional ophthalmoscopic examination or fluorescein angiography. In SLO and indocyanine-green studies, controls and control angiograms showed no choroidal abnormalities. Iris nodules were noted in 25 eyes (76%) of 14 patients (82%) and eyelid neurofibroma in five patients (29%). Interpretation The bright patchy regions noted under infrared fundus examination and the corresponding hypofluorescent areas seen on indocyanine-green angiograms are probably of choroidal origin. The high frequency (100%) of these abnormalities suggests that the choroid is one of the structures most commonly affected by neurofibromatosis 1.