A-Z of posterior eye conditions

Leber’s congenital amaurosis

DESCRIPTION Infant child with oculodigital The word ‘amaurosis’ refers to partial syndrome in Leber’s or complete vision impairment, partic- congenital amaurosis. Figure ularly when there is no obvious cause. courtesy of Kanski J J Clinical Leber’s congenital amaurosis is a retinal Ophthalmology 4th Edition, dystrophic disease that is inherited as an Butterworth-Heinemann autosomal recessive trait. It is characterised by a bilateral severe vision loss, if not blindness, at birth or shortly thereafter, and should be suspected if an infant presents with vision loss, nystagmus and poor pupil reflexes in the presence of normal or near normal fundi. The few cases that retain reasonable vision in their early years tend to decline with time so that in adulthood they are legally blind. A variety of fundus changes may lead to a ance of white flecks and a salt-and-pepper MANAGEMENT difficulty in diagnosis (see below). mottling, macular dysplasia and raised Most patients are otherwise normal optic discs (pseudopapilloedema). With Advice although certain potential systemic time optic disc pallor and attenuated There is no treatment for the ocular associations may be seen. These include arterioles develop. Fluorescein angiogra- complications of this disease. mental retardation, deafness and renal, phy is rarely helpful to the diagnosis and skeletal and cardiac abnormalities. both photopic and scotopic components Genetics of the electroretinogram are severely Paediatric and genetic consultations SYMPTOMS abnormal or even absent. should be obtained. There are few symptoms other than poor vision in those old enough to appreciate PREVALENCE Refractive correction or LVAs it. The parents may have noted roving It has been estimated that Leber’s congen- If necessary, spectacles should be eye movements and strabismus, as well ital amaurosis has a prevalence of about prescribed following refraction under as a poking or rubbing of the eyes which 3 per 100,000 live births. cycloplegia to enhance any remaining is known as the oculo-digital sign. vision. DIFFERENTIAL DIAGNOSIS SIGNS If peripheral pigmentary changes are External signs include nystagmus and present there may some confusion with The full series of these articles will be available in the strabismus. Keratoconus is quite common retinitis pigmentosa. Similarly, macular book Posterior Eye Disease and Glaucoma A-Z by Bruce and has been related to the propensity dysplasia can resemble macular scarring AS, O’Day J, McKay D and Swann P. £39.99. For further for eye rubbing. Continuous eye rubbing from toxoplasmosis. Optic atrophy as an information click on the Bookstore at opticianonline.net (oculo-digital syndrome) may cause a loss early finding in some Leber’s patients may of orbital fat, leading to enophthalmos. be confused with autosomal recessive ● Adrian Bruce is a Chief Optometrist at the Victorian High hypermetropic and high myopic optic atrophy. The disease also needs to be College of Optometry and a Senior Fellow, Department refractive errors may be seen, with the distinguished from congenital stationary of Optometry and Vision Sciences, The University of former being more common. Pupil night blindness and achromatopsia. Melbourne. reflexes to light are sluggish and may be ● Justin O’Day is an Associate Professor in the absent altogether. Cataracts frequently Department of Ophthalmology, The University of develop in the second decade. Melbourne and Head Of Neuro-Ophthalmology Clinic, As noted above, fundus changes can Royal Victorian Eye and Ear Hospital. be very variable. The fundi may appear ● Daniel McKay is a Medical Officer at the Royal normal at birth and in infancy, with Victorian Eye & Ear Hospital. changes developing in the first few ● Peter Swann is Associate Professor in the School of years of life. These include a peripheral Optometry, Queensland University of Technology. pigmentary degeneration, the appear- ● opticianonline.net 25.05.07 | Optician | 59