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At a glance

It is an inherited degenerative disease of the retina that appears at birth or in the first few months of life and is characterized by severely decreased vision manifesting at birth or shortly thereafter. Other ocular anomalies may include sensory (wandering) nystagmus, amaurotic pupils, deep-set eyes, photophobia, and eventually severe vision loss leading to blindness. Central nervous system anomalies have been described in some patients.

N.B.: Do not confuse with Leber hereditary optic neuropathy that is classified as mitochondrial inherited degeneration of the retina leading to acute or subacute los of vision. It affects predominantly young adult males (☞Leber Hereditary Optic Neuropathy).

History

First described by the German ophthalmologist Theodor von Leber (1840-1917) in 1869.

Incidence

It is established at 3:100,000 neonates. It is the most common cause of inherited blindness in childhood.

Genetic inheritance

It is presumed inherited as an autosomal recessive disorder. It is a disorder thought to be caused by abnormal development of photoreceptor cells and 18 genetic loci for LCA have been identified. It is no longer considered one medical condition but rather multiple disorders, which can be classified into three different categories: (1) aplasia, resulting in abnormal embryologic formation of photoreceptors; (2) early degeneration of photoreceptors with progressive cell death; and (3) dysfunction of the photoreceptors with normal retinal anatomy. Gene therapy has been used with some success in treating one type of LCA caused by the RPE65 mutations.

Clinical aspects

Vision is already significantly reduced at birth or shortly thereafter. Sensory (wandering) nystagmus and lack of visual responsiveness alert the parents, usually within the first months of life. Initial examination may reveal a normal retina and a fundus appearance that either is essentially normal or reveals a progressive pigmentary retinopathy. The pupils are amaurotic and the eyes deep sunken. However, the final diagnosis is made by electroretinography that shows only small (at high intensities) or no photopic responses. Both cone and rod responses are affected. Patients are described as frequently poking and rubbing their eyes (the so-called “Oculodigital Reflex” of Leber and Franceschetti), which is not specific to LCA because it is observed in other forms of amaurosis (Leber was the first to describe this phenomenon). Other associated ocular features may include ptosis, strabismus, keratoconus/keratoglobus, cataracts, microphthalmos, macular coloboma pigmentary retinopathy and maculopathy, optic disc edema, retinal vascular changes, and high-grade hyperopia or myopia (less common). By early adolescence, the retina of LCA patients may undergo significant changes. Retinal blood vessels often become narrow and constricted, and pigmentary changes similar to those found in retinitis pigmentosa may affect the retinal pigment epithelium. Despite these changes, vision does not usually deteriorate further. Visual acuity in LCA patients is most often limited to the level of finger counting or detection of bright light. Some patients are ...

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