Ectopic lens

An ectopic lens (ectopia lentis) is a displacement of the eye's lens from its position for various reasons. The degree of ectopia varies: there may be a slight displacement with the lens remaining in the area of the iris (a subluxated lens), or conversely a complete displacement of the lens from the iris area (a luxated/dislocated lens).

Signs and symptoms of an ectopic lens

• Impairment of visual acuity
• Appearance of astigmatism
• Double vision in one eye (monocular diplopia)
• Tremor of the iris during eye movement (iridodonesis) – a simple test that all ophthalmologists know how to perform.

Complications of an ectopic lens

• Cataract
• Displacement of the lens into the anterior chamber, which can lead to pupillary block and angle-closure glaucoma.
• Displacement of the lens into the posterior segment.

Causes of an ectopic lens

• Trauma – the most common cause
• Marfan syndrome – in 2/3 of patients there will be an ectopic lens, usually bilateral and symmetrical. The displacement of the lens is usually in a superotemporal direction.
• Homocystinuria – up to 80% of patients with this disease will suffer from an ectopic lens, usually bilateral and symmetrical. The displacement of the lens is usually in an inferonasal direction.
• Aniridia – absence of the iris.
• Congenital glaucoma
• Ehlers-Danlos syndrome
• Hyperlysinemia
• Sulfite oxidase deficiency
• Simple ectopia lentis (an isolated disorder of ectopic lens – usually inherited in an autosomal dominant manner).
• Ectopia lentis et pupillae – an autosomal recessive disorder that involves both the lens and the iris. The lens and iris are pushed in opposite directions and the iris has an abnormal shape. The disorder is usually bilateral but not symmetrical, and it is accompanied by additional ocular impairments.