Leukodystrophies can affect vision. Blindness or reduced vision that is congenital (i.e. present from birth) will have a different effect and require different care to loss of sight over time. This is because people born with reduced vision cannot use past visual experience to relate to the world around them.
Nystagmus, or constant uncontrolled eye movements, is a common symptom of those leukodystrophies that affect vision. Nystagmus can be either congenital (present from birth or early infancy) or acquired (developing later in life).
People with nystagmus do not necessarily have severely reduced vision. Many experience large variations, with vision worsening when eye movements increase in frequency or speed. The eye movements are not painful but may cause the eyes to feel tired and achy, particularly when doing tasks that require high concentration.
People who develop nystagmus over time (i.e. those with acquired nystagmus) often find that their brain has not adapted to the constant movements of their eyes. This gives them a constant and sometimes disabling sensation that everything is moving around them. This rarely happens to those who have nystagmus from birth.
There is no cure for nystagmus, but those affected should have regular eye tests so that issues like long or short sight can be addressed through glasses or contact lenses where appropriate. This does not affect the nystagmus but makes sure that the person’s sight is as good as possible. Conditions which can be affected by nystagmus include:
A cataract is when the lens of the eye become cloudy instead of transparent. This makes the vision cloudy or misty. Cataracts are common in leukodystrophies. Some conditions cause a baby to be born with cataracts, while in others cataracts develop over time. Cataracts can occur in one or both eyes. Depending on severity, cataracts may require surgery to remove the cloudy lens. This is the most common operation performed in the UK and has a high success rate. In some cases the surgeon fits a plastic replacement lens. In other cases, the affected person must use glasses or contact lenses. If cataracts are present from birth, the surgery is usually done in the first 2 months of life. Cerebrotendinous Xanthomatosis; Hypomyelination with Congenital Cataracts; POLR3 related leukodystrophy are the leukodystrophies most commonly affected by cataracts.
Strabismus, or squint, occurs when one eye is fixed in one position, while the other looks forward. Without treatment, children with strabismus develop a ‘lazy eye’ (amblyopia), and vision in this eye deteriorates. Squint and lazy eye should be assessed and treated as soon as possible, otherwise vision problems can become permanent. Treatments for strabismus include corrective prescription glasses, wearing an eye patch to improve the vision in the lazy eye, and surgery. Surgery to adjust the position of the eye muscles is used if other treatment proves ineffective. It is usually done as day surgery.
Strabismus is most likely to affect those with the following conditions: Alpha-Mannosidosis; Oculodentodigital Dysplasia with cerebral white matter abnormalities; Peroxisomal Acyl CoA Oxidase deficiency.
Optic atrophy is an abnormality in which the optic nerve (the nerve that carries signals from the eye to the brain) becomes damaged and its function deteriorates. This causes visual problems such as blurred vision, difficulties with colour or peripheral vision, reduced sharpness in vision, and in some cases blindness. There is no treatment for optic atrophy. Conditions most likely to be affected by optic atrophy are 3-Methylglutaconic Aciduria type 1; Peroxisomal Acyl CoA Oxidase deficiency; POLR3 related leukodystrophy; Vanishing White Matter Disease.