This 10 year-old girl recently developed bilateral poor eyesight. She required +11DS glasses to achieve 6/6 vision. One of her parents had a history of dissecting aneurysm.

a. What is the most likely cause for her poor vision?

Bilateral lens subluxation (Figure 2).

Her prescription suggests that she is aphakic. With a family history of dissecting aneurysm, lens subluxation due to Marfan's syndrome is the most likely diagnosis. The lens subluxation in Marfan's syndrome is typically superotemporal.

b. What other ocular signs may be present?

Anterior segment:

• keratoconus
• glaucoma which may be caused by angle anomaly or from lens subluxation
• hypoplastic dilator pupillae
• myopia usually lenticular with normal axial length

Posterior segment:

• lattic degeneration and increased incidence of retinal detachment

c. What systemic conditions may be present?

• long limbs with the arm span longer than height
• arachnodactyly
• pectus excavatum
• joint laxity
• high arched palate
• underdevelopment of muscles (hernias)
• cardiovascular abnormalities including aortic incompetence, dissecting aneurysm, mitral incompetence
• hydroxyproline in urine