The lens, together with the cornea, is responsible for refracting light onto the retina. Zonular fibers 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.
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Anatomy of the lens
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- Definition: displacement of the lens of the eye
- Trauma (most common)
- Ocular disease
- Simple ectopia lentis: a hereditary disorder in which zonular fibers degenerate, leading to lens dislocation.
- Ectopia lentis et pupillae: displaced pupils and lenses (usually in opposite directions); rare congenital disorder
- Pseudoexfoliation syndrome (mean age of onset is 69–75 years): deposition of fibrillary residue from the lens and iris onto the lens capsule, ciliary body, zonules, iris, and corneal endothelium
- Systemic disease
Subluxation of the lens
- Partially displaced lens; still within the hyaloid fossa and attached to the ciliary body
- Little to no loss of visual acuity: If the displacement is more severe, monocular double-images, significant optical distortions, and visual impairment may occur.
- : superior, temporal subluxation of the lens (upward and outwards)
- : inferior, medial subluxation of the lens (downward and inwards)
- Luxation of the lens
- Subluxation of the lens
Diagnostics: visual acuity, slit lamp examination, retinoscopy, and ultrasound of the eye
- Ophthalmological assessment may include visual acuity testing, slit lamp examination, retinoscopy, ultrasound of the eye, and tonometry
- Findings include:
- Evaluation for underlying Marfan syndrome or homocystinuria
- Refractive correction
- Treatment of the underlying condition
- Definition: absent lens
- Surgical removal of the lens (most common)
- Trauma (rare)
- Congenital (very rare)
- Clinical features
- Refractive correction with aphakic glasses or contact lenses