Marfan's Syndrome
Marfan's Syndrome is a heritable disorder of connective tissue with characteristic skeletal, cardiovascular, and ocular manifestations. Dislocation of the lens is a frequent finding.Since the syndrome is inherited in an autossomal dominant fashion with a high degree of penetrance, other family members are frequently found to be affected.
In the classic form, Marfan's syndrome is characterized by the following: Cardiac anomalies such as aneurysms of the ascending aorta and aortic regurgitation. Skeletal anomalies in which the patient's limbs are long compared with the trunk. Arachnodactyly, pectus deformities, mild joint laxity and high arched palate are also seen.Muscular underdevelopment, leading to a high incidence of hernias.
The characteristic eye findings in Marfan's syndrome include: Lens subluxation, angle anomaly, glaucoma, hypoplasia of dilator muscle, axial myopia and retinal detachment.
Subluxation of the lens is the most common ocular abnormality (fig1.), wich is bilateral, symetrical, and upward is present in 80% of cases. The dislocation may be complete, with the lens floating free within the vitreous cavity.Iridodonesis(tremulousness of the iris) may occur from nonsupport of the overlying iris by the lens.
The axial length of the globe is increased in Marfan's patients leading to moderate to severe myopia as the most common refractive error.Retinal detachment is more common than in the normal population.Glaucoma may be the result of the angle anomaly or it may be associated with lens subluxation.
The essential biochemical defect of Marfan's syndrome is unknown, but a single primary defect in collagen is suspected.To diagnose Marfan's syndrome, people with affected relative need features in at lest two systems.People with no family history need features in the skeletal system, two other systems, and one of the major criteria of ectopia lentis, dilation of the aortic root, or aortic dissection.Mutations on the cromossome 15 cause Marfan's syndrome but no diagnostic laboratory tests exists.
Diferential diagnosis must be done with Weill-Marchesani syndrome and Homocystinuria, but in a big number of cases Marfan's syndrome is characteristic.
Children with Marfan's syndrome require regular ophtalmologic surveillance to correct visual acuity and thus prevent amblyopia.Patients of all ages require echocardiography annualy to monitor aortic diameter and mitral valve function, and should use standard endocarditis profilaxis.
New surgical techniques are being used in patient's with ectopia lentis. It depends on the hardness of the lens and its location within the vitreous cavity.
Jack J.Kansky. Clinical Ophtalmology - A Systemic Approach. Second edition
Daniel H. Gold; Thomas A. Weingeist. The Eye in Systemic Disease
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