Chapter

Ectopia Lentisand Associated Systemic Disease

Elias I. Traboulsi and Suneel S. Apte

in Genetic Diseases of the Eye, Second Edition

Second edition

Published on behalf of © Elias I. Traboulsi

Published in print January 2012 | ISBN: 9780195326147
Published online October 2012 | e-ISBN: 9780199975181 | DOI: http://dx.doi.org/10.1093/med/9780195326147.003.0043

Series: Oxford Monographs on Medical Genetics

Ectopia Lentisand Associated Systemic Disease

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The crystalline lens collects light rays and images and keeps them in focus on the retina by changing its refractive power through the complex process of accommodation. The zonular fibers connect the ciliary processes to the equatorial region of the lens (Fig. 43.1) and suspend the latter in a centered position behind the iris and pupil. Zonular fibers are rich in fibrillin, which in turn is rich in cysteine and extensively disulfide bonded; the zonule is hence disrupted in diseases of sulfate metabolism such as homocystinuria and sulfite oxidase deficiency and in the Marfan syndrome (MFS), where abnormalities of fibrillin-1 cause the clinical manifestations of the disease. Recent research has identified mutations in members of the ADAMTS family of genes in a few diseases that feature ectopia lentis (EL), suggesting the potential role of ADAMTS proteins in the normal formation of the zonule and possible interactions with fibrillin-1. Loss of normal zonular support leads to displacement of the lens from its normal position and to changes in its curvature and refractive power.

Chapter.  14521 words.  Illustrated.

Subjects: Clinical Genetics ; Ophthalmology

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