Ocular Pathology

Anatomy and pathology of the human eye. Use it to review eye pathology for Ophthalmology Board Review or OKAP.

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Wednesday, July 04, 2007

Marfan's Syndrome- Lens Displacement

Definition: Marfan's syndrome is a disorder of connective tissue with ocular, musculoskeletal, and cardiovascular manifestations.
Incidence/Prevalence: the most common cause of lens dislocation from a genetic mutation. The incidence is about 0.7/100,000 live births. The prevalence is 7-17/100,000 population.
Etiology: Marfan's syndrome is an autosomal dominant disorder caused by mutations in the fibrillin gene on chromosome 15. Fibrillin is a glycoprotein that is a major component in elastic tissue and is important in lens zonules. 50-80 percent of patients with Marfan’s syndrome have ectopia lentis.
Clinical Findings: Lens dislocation upward or superortemporally is the most common manifestation of ectopia lentis due to inferior zonule compromise. However, a 360 degree compromised lens zonule is possible in which case the lens floats in the posterior chamber.
Histopathology: The lens is usually displaced upward or in a superotemporal direction, and axial myopia is often present. In the accompanying images the lens is displaced upward because of inferior zonular compromise. The inferior border of the lens is concave in areas of zonular dehiscence (arrows #1 in gross photo). The displacement superiorly is evident by the increased distance between the lens and iris inferiorly (arrow #3 below) and their near apposition superiorly. The lens may bulge posteriorly (arrow #4 in microscopic photo). Sections generally show some morphologically normal appearing zonular fibrils that are decreased in number, and others that are short and in disarray. Associated findings include iris hypoplasia with transillumination defects and numerous iridociliary processes (arrows 2).
Treatment: When visual symptoms cannot be corrected medically, lens removal with trans-scleral or iris fixation may produce acceptable results. Sulcus placement may be difficult especially if there are numeorus enlarged cilio-iridal processes that bridge the ciliary sulcus and block the placement of a haptic.

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