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.