Leber congenital amaurosis

Leber congenital amaurosis (LCA) is an inherited retinal condition. It's a rare eye disease that usually first becomes apparent in young adult life (10-30 years old) or rarely, earlier. It's the leading reason for inherited vision loss in children.

Leber congenital amaurosis can cause sudden painless loss of vision in one or both eyes. It can be difficult to learn that your child may have a visual impairment. However, with practical and emotional support, your family can adapt and help your child reach their potential.

Leber congenital amaurosis symptoms

Leber congenital amaurosis is a severe retinal dystrophy and is sometimes known as Leber hereditary optic neuropathy or Leber optic atrophy.

The symptoms typically start in the teenage years or twenties but rarely can start in early childhood. It can lead to blindness or severe vision loss and tends to progress more quickly than other retinal diseases.

Leber congenital amaurosis leads to poor visual function because it affects the optic nerve at the back of the eye. Signs and symptoms can include:

• Severely reduced visual acuity in one or both eyes
• Pupils that are slow to respond to light
• Night blindness
• Sensitivity to light (photophobia)
• Farsightedness (hyperopia)
• Involuntary eye movement (nystagmus)
• Crossed eyes (strabismus)

Sometimes the disease is associated with syndromes that involve developmental delay and learning disabilities, although only in a minority of cases.

Different types of Leber congenital amaurosis can present with different symptoms. Some types are relatively stable. Others lead to progressive degeneration of sight. Most often the basic symptoms and signs include nystagmus, sensitivity to light and sluggish pupil responses.

Babies and children with vision impairment can be prone to rubbing their eyes a lot, stimulating the retina to detect light. This rubbing can lead to a condition called keratoconus, which damages the cornea at the front of the eye. They may also lose fatty tissue around the eyes giving eyes a sunken appearance (Source: Retina UK).

What causes Leber congenital amaurosis?

A defect in a number of genes causes Leber congenital amaurosis. The defect affects how photoreceptor cells at the back of the eye work. These retinal cells detect light and convert it into electrical signals to the brain, enabling us to see.

There are different forms of LCA, depending on which specific gene has the fault. Some types of Leber congenital amaurosis remain stable, while others worsen with time, leading to degeneration in eyesight.

How is Leber congenital amaurosis diagnosed?

Babies and children should have their sight checked at key milestones in their early years, including newborn eyesight screening. Leber congenital amaurosis might be detected at this early stage. If you have concerns about your baby or child's eyesight, speak to your health visitor or GP. They may refer your child to an ophthalmologist (eye doctor) to examine their eyes.

An ophthalmologist will look for clinical signs and symptoms to help decide which tests to do. The symptoms of Leber congenital amaurosis can be similar to some other diseases, including Loken-Senior syndrome and Joubert syndrome.

To reach a diagnosis of LCA, an eye doctor may do a test called an electroretinogram (ERG) which looks at how the retina works. Other tests include ophthalmoscopy (looking closely at the eye with a special light and magnifying tool), visual field tests, colour vision tests, and how the pupils react to light.

If your child does have Leber congenital amaurosis, then genetic testing may be used to identify which gene is responsible for the condition. Knowing the gene involved may be important if new treatments become available in the future, and for genetic counselling. A specialist can look at your child's symptoms to help decide which genes to test.

Treatment for Leber congenital amaurosis

Unfortunately, there's currently no cure for most cases of Leber congenital amaurosis. A lot of research and clinical trials are happening to explore gene therapy as a potential treatment for the future.

One gene therapy called Luxturna has been approved in the UK to treat Leber congenital amaurosis caused by a fault in the RPE65 gene. The RPE65 gene is thought to be responsible for between 6-16% of cases of Leber congenital amaurosis (Source: NICE). Luxturna is given by injection into the eye under general anaesthetic.

Gene therapy targets a specific gene. That's why genetic testing to confirm the exact gene involved is important if you want to know about future developments in treatment that may be relevant.

There are ways to help your child make the most of their vision, such as correcting any refractive errors with prescription glasses. It's also best to discourage your child from poking and rubbing their eyes which can cause keratoconus. If your child has some useful vision, they will have regular eye exams to monitor their sight.

When to get medical advice

If you're worried about your baby or child's sight, speak health visitor or GP. All babies have a newborn screening check, and you can ask about your child's sight at one of their regular health and development reviews.