An 11-year-old girl is brought to the clinic due to acute vision changes. Two hours ago, the symptoms began at school after the patient bumped into another student while walking to her honors class. After sitting, she noticed difficulty seeing out of the right eye. The patient has high myopia and recently received new glasses and an updated prescription. Vital signs are normal. Visual acuity with her glasses on shows 20/50 in the right eye and 20/20 in the left. The pupils are equal and reactive bilaterally. Extraocular muscles are intact, but there is vibration of the iris during left and right movement, a finding consistent with lens dislocation. In addition to ophthalmologic management, which of the following is indicated in this patient?
Lens dislocation (ectopia lentis) | |
Pathogenesis |
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Clinical features |
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Management |
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This patient has lens dislocation (ectopia lentis), a condition in which the lens detaches from the ciliary body. Poor vision is typically the first sign; a tremulous iris during eye movement and a displaced lens are seen during examination. Although blunt ocular trauma from a high-speed object (eg, golf ball) is the most common cause, an underlying genetic condition should be suspected after minimal or no trauma, as in this patient.
Two classic causes associated with ectopia lentis are homocystinuria and Marfan syndrome. In contrast with this patient who is an honor student, homocystinuria is associated with intellectual disability and thrombotic events. Marfan syndrome is characterized by defective fibrillin, an integral component of the ligaments that hold the lens in place. The characteristic Marfanoid habitus (eg, tall stature) may not be apparent in young children; high myopia (nearsightedness requiring ≥6 diopters of correction) and lens dislocation may be the presenting features, as in this patient.
Aortic root disease (eg, dilation, dissection), the major cause of morbidity and mortality in Marfan syndrome, can develop at a young age, and any patient with suspected Marfan syndrome (eg, unexplained ectopia lentis) requires echocardiography for confirmation.
(Choice A) CHARGE and Alport syndrome are genetic conditions associated with hearing loss and ophthalmic findings. Coloboma (hole in one of the eye structures) and intellectual disability are typical of CHARGE syndrome. Alport syndrome can include hematuria and lens protrusion in boys; however, lens dislocation is not typically seen in either condition. Marfan syndrome is not associated with hearing loss.
(Choice B) Although skeletal findings are common with Marfan syndrome (eg, long extremities, joint hypermobility), skeletal maturity and bone age are normal. Moreover, evaluation for life-threatening cardiac features associated with Marfan syndrome should be the priority.
(Choice D) Karyotype analysis can detect genetic conditions (eg, Down syndrome), which has a higher incidence of myopia and early-onset cataracts but is not associated with lens dislocation.
(Choice E) MRI of the head can assess for a CNS tumor (eg, retinoblastoma), which can cause vision loss but not lens dislocation.
(Choice F) Renal ultrasound can evaluate for a horseshoe kidney, as seen in Turner syndrome. Ocular abnormalities associated with this syndrome include astigmatism and farsightedness.
Educational objective:
Lens dislocation typically occurs after blunt trauma to the eye. However, ectopia lentis following minimal or no trauma should prompt evaluation for Marfan syndrome, including echocardiography to detect associated aortic root disease.