Leber’s congenital amaurosis (LCA) is an eye disease that primarily affects the retina, the inner eye tissue on which images are projected and where light signals are converted into electrical impulses reaching the brain and generating vision.

It is described as the sudden loss of vision in one of the two eyes due to the absence of blood circulation in the retina.. Patients with amaurosis report that a grey or black spot appears in the visual field and moves down the eye until all vision is compromised for a few seconds or minutes.

This disease causes severe visual impairment in children from the first months of life and can be recognised by the persistence of nystagmus (continuous pendular movements of both eyes) from the third month of life, intense photophobia and enophthalmos (sunken eyes). Vision loss in children with ABI occurs when the photoreceptor cells of the retina (rods and cones) stop functioning. Cones (allow daytime vision and colour vision) and rods (allow vision at night or in dimly lit places).

AKI is characterised by severely reduced visual acuity (≤ 20/400) or blindness during the first year of life. Depending on the genetic cause, slow pupillary response, wandering eye movements, photophobia, high hyperopia, nystagmus, convergent strabismus or keratoconus may be present.

Franceschetti’s oculo-digital sign, consisting of squeezing, pressing and rubbing the eyes, is characteristic of the disease and allows the diagnosis to be established. Leber congenital amaurosis may also be associated with mutations in genes linked to other syndromes presenting with neurodevelopmental delay, intellectual disability, apraxia (eye movement difficulty) and renal dysfunction.

There are two types of Leber’s congenital amaurosis, genetic and fugax, which is often caused by a vascular problem that causes one or more transient symptoms.

There are 17 or so subtypes of genetic or permanent Leber’s congenital amaurosis, which are caused by mutations in different genes, although there are 30% of causes that are still under investigation.

Its prevalence is estimated at 1 to 9 cases per 100.000 population and accounts for 5% of all retinal dystrophies and 20% of paediatric blindness. It is therefore a rare but serious eye disease with a genetic basis that begins to show signs as early as the first year of life.

The company doing research in the field of this disease is Sylentis.