Leber congenital amaurosis (LCA) refers to a group of diseases that cause severe vision loss in infancy. The vision loss is due to abnormal function and later degen-eration of the retina, the layer in the back of the eye that captures images, similar to the film in a camera. With LCA, the light-sensing (photoreceptor) cells of the retina do not function properly, causing an inability to capture images.
THE RETINA is a thin layer of light-sensitive nerve tissue that lines the back of the eye (or vitreous) cavity. When light enters the eye, it passes through the iris to the retina where images are focused and converted to electrical impulses that are carried by the optic nerve to the brain resulting in sight.
Leber congenital amaurosis LCA is inherited (passed down from parents) through their genes. There are at least 19 different gene mutations that can be passed down and cause the spectrum of LCA. The affected genes instruct our body to make proteins that are necessary for vision.
In Leber congenital amaurosis LCA, the abnormal genes are typically passed down in an autosomal recessive pattern. This means that in order to have the disease, the child needs two abnormal genes, one from each parent. Both parents are typically unaware they carry the mutation, as they do not have vision loss.
On ophthalmic examination, patients with LCA often initially have a relatively normal-looking retina, as the degeneration of the retina occurs later. The diagnosis can be confirmed with an electroretinogram (ERG), which measures the activity of the retina. LCA patients classically have a “flat” ERG, which suggests virtually no retinal function. Later, the retinas become damaged and show thinning, often with pigmentary changes, and the optic nerve heads become pale.
Genetic testing is important to determine which gene is abnormal. Genetic counseling can also help parents and patients understand the inheritance and the risk of future children having the condition. Some mutations cause problems in other organs of the body, including developmental delay, so it is important for affected children to be evaluated by a pediatrician experienced in treating inherited diseases.
Electroretinogram (ERG): Non-invasive test that measures the electrical “circuitry” of the eye by assessing the response of the retina’s light-sensitive cells to stimulus.
Retinitis pigmentosa (RP): A group of inherited (passed down from parents) diseases causing retinal degeneration and blindness. Individuals with RP lose their vision because photoreceptor (light-sensing) cells of the retina gradually degenerate and then die
THANK YOU TO THE AUTHORS
Sophie J. Bakri, MD Audina Berrocal, MD
Thomas Ciulla, MD, MBA Geoffrey G. Emerson, MD, PhD Roger A. Goldberg, MD, MBA Dilraj Grewal, MD
Larry Halperin, MD Vi S. Hau, MD, PhD
G. Baker Hubbard, MD Talia R. Kaden, MD
M. Ali Khan, MD
Mathew J. MacCumber, MD, PhD Timothy G. Murray, MD, MBA Oded Ohana, MD, MBA Jonathan L. Prenner, MD
Carl D. Regillo, MD, FACS Naryan Sabherwal, MD Sherveen Salek, MD Andrew P. Schachat, MD Michael Seider, MD
Janet S. Sunness, MD Edward Uchiyama, MD Allen Z. Verne, MD Christina Y. Weng, MD, MBA Yoshihiro Yonekawa, MD
John T. Thompson, MD
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