Neurofibromatosis and the Eyes

Neurofibromatosis is an inherited condition in which benign tumours grow on nerves and skin. It is among the most common genetic conditions and can affect numerous organs, including the eyes. Two main forms are distinguished: the more common neurofibromatosis type 1 (NF1, also known as von Recklinghausen disease) and the rarer neurofibromatosis type 2 (NF2).

Neurofibromatosis type 1 (NF1)

NF1 affects about 1 in 3 000 to 5 000 people and is inherited in an autosomal dominant manner. In half of all cases, however, the genetic change arises spontaneously, without any family history.

Typical features

• Café-au-lait spots: light brown patches of skin that are often visible at birth
• Neurofibromas: benign nodules on or under the skin and on nerves
• Freckle-like spots: in the armpits and groin
• Skeletal changes: scoliosis, bowing of the lower leg
• Learning difficulties: in a proportion of children

Eye changes in NF1

The eyes are frequently involved in NF1:

• Lisch nodules: small, harmless nodules on the iris, which occur in over 90 % of adult NF1 patients and represent an important diagnostic sign
• Optic pathway glioma: a benign tumour of the optic nerve, which occurs in about 15 % of children with NF1. It can impair vision and requires regular monitoring. Many optic gliomas grow slowly or not at all and need no treatment.
• Plexiform neurofibroma of the lids: soft, sometimes growing tumours of the eyelids, which can obstruct vision and cause amblyopia
• Choroidal spots: flat changes of the choroid, which can be made visible with OCT
• Glaucoma: raised intraocular pressure occurs in some patients, particularly where a neurofibroma is present in the region of the upper lid
• Amblyopia and strabismus: squinting and reduced vision occur more frequently

Neurofibromatosis type 2 (NF2)

NF2 is considerably rarer and affects about 1 in 25 000 people. Its main features are:

• Vestibular schwannomas: benign tumours of the auditory nerve, usually on both sides
• Cataract: clouding of the lens, which often appears as early as young adulthood
• Other tumours: meningiomas and schwannomas

Diagnosis

The diagnosis of neurofibromatosis is made on the basis of clinical criteria and confirmed by genetic testing where needed. For NF1, at least two of the following features must be present: café-au-lait spots, neurofibromas, axillary or inguinal freckling, optic pathway glioma, Lisch nodules, characteristic bone changes, or an affected first-degree relative.

Ophthalmological care

Children with neurofibromatosis need regular ophthalmological monitoring:

• Annual check-ups from the time of diagnosis, more frequently in younger children
• Visual acuity tests and visual field testing to detect optic pathway gliomas
• Examination of the iris for Lisch nodules
• Measurement of intraocular pressure where there is a risk of glaucoma
• MRI of the head where an optic pathway glioma or other central nervous system tumour is suspected

Most eye changes in NF1 take a mild course and require no active treatment. Where treatment is necessary, it is directed at the particular complication, whether that is amblyopia treatment, glaucoma therapy, or the monitoring or treatment of an optic pathway glioma in collaboration with oncologists and neurosurgeons.