Ectopia lentis refers to subluxation or dislocation of the lens of the eye secondary to dysfunction or disruption of zonular fibres. It is most commonly due to trauma. The commonest atraumatic aetiologies are Marfan syndrome and homocystinuria.
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Pathology
Aetiology
trauma
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systemic and syndromic disorders
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typically upwards and out
most common spontaneous cause 2
homocystinuria - typically downwards
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primary ocular disorders
infective conditions, e.g. syphilis
Marfan syndrome, homocystinuria, and Weil-Marchesani syndrome account for the vast majority of non-traumatic cases.
Radiographic features
Ultrasound
Sonographic features of lens malposition differ based upon the degree of luxation as follows 5:
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subluxation
unilateral deviation of the lens margin posteriorly into the anechoic vitreous body
the contralateral margin remains fixed adjacent to the iris
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complete luxation
the lens assumes a dependent position in the vitreous
demonstrates free mobility with eye movements
Associated findings include:
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traumatic cataract
increased echogenicity of the lens is suggestive
CT
CT will clearly demonstrate the subluxed or dislocated lens. It has the advantage of identifying additional injuries in the context of trauma.
Treatment and prognosis
Complications
An anterior dislocation/subluxation carries greater complications than a posterior one. Such complications include:
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