• Clinical science

Diseases of the lens

Abstract

The lens, together with the cornea, is responsible for refracting light onto the retina. Zonular fibers (which make up the zonule of Zinn) attach the lens to the ciliary body, which holds the lens in position and determines its degree of accommodation. Pathological conditions of the lens include cataracts, displacement of the lens, and aphakia. Cataracts, in which age-related degenerative processes lead to clouding of the lens, are the most common disease of the lens. Ectopia lentis, a displacement of the lens, can be caused by ocular diseases, trauma, or systemic conditions. While a partially displaced lens (subluxation) involves little to no loss of visual acuity, complete displacement of the lens (luxation) results in severe visual impairment. Subluxation is common in individuals with Marfan syndrome and homocystinuria. Treatment of a displaced lens involves refractive correction and/or surgical removal of the lens. Aphakia is the absence of the lens, which can be congenital or secondary to trauma or surgery (e.g., cataract surgery). Clinical features include poor visual acuity and total loss of visual accommodation. Treatment consists of refractive correction with aphakic glasses, contact lenses, or surgery.

For more information on cataracts, see the corresponding learning card.

Anatomy of the lens

For more details, see gross anatomy of the eye and lens.

Ectopia lentis

In Marfan syndrome, the lens subluxates superiorly and temporally (upward and outwards). In homocystinuria, the lens subluxates inferiorly and medially (downward and inwards).

References:[1][2]

Aphakia

  • Definition: absent lens
  • Etiology
    • Surgical removal of the lens (most common)
    • Trauma (rare)
    • Congenital (very rare)
  • Clinical features
  • Diagnostics
    • Assessment of visual acuity
    • Slit-lamp examination
  • Treatment
    • Refractive correction with aphakic glasses or contact lenses
    • Surgery
  • Complications: retinal detachment

References:[3][4]