Answer 4 Echocardiography. This patient presents with glaucoma as a complication of ectopia lentis, which obstructed the flow of aqueous humor. When ectopia lentis is diagnosed, one must rule out the systemic causes in addition to local causes. Trauma to the eye is the most common local cause of ectopia lentis; however, Marfan syndrome is the most common among systemic causes, followed by homocystinuria. Echocardiography can identify aortic root abnormalities such as aortic root dilatation or aortic dissection, which are major signs of Marfan syndrome. Homocystinuria must be ruled out even in patients suspected to have Marfan syndrome because treatment is available for this disorder. Serum methionine levels are elevated in homocystinuria. Serum lysine is elevated in hyperlysinemia, which is a rare inborn error of amino acid metabolism and can be associated with ectopia lentis. In assessing levels of both serum lysine and methionine, the results of the test do not rule out Marfan syndrome. Although abdominal CAT scans can identify abdominal aortic aneurysm, they are not diagnostic of Marfan syndrome. Slit-lamp examination is performed to identify ectopia lentis (subluxation) in situations where it cannot be identified by routine eye examination. As it is already known that the patient has ectopia lentis, this test is unnecessary. Click here to return to the questions

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