Subluxation and Dislocation of the Lens (Ectopia Lentis)

Subluxation or dislocation of the lens, also called ectopia lentis, refers to a partial or complete displacement of the crystalline lens.
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Subluxation and Dislocation of the Lens

Subluxation or dislocation of the lens, also called ectopia lentis, refers to a partial or complete displacement of the crystalline lens from its normal position due to the weakening or rupture of zonular fibers.

  • Subluxation: The lens is partially displaced but remains within the pupillary area.
  • Dislocation (Luxation): The lens is completely displaced out of the pupillary area, either into the anterior chamber or the vitreous cavity.

Subluxation and Dislocation of the Lens

Causes of Lens Subluxation/Dislocation

A. Traumatic Causes

  • Blunt trauma (e.g., sports injury, road traffic accident)
  • Penetrating trauma (e.g., sharp object injury, gunshot wounds)

B. Non-Traumatic Causes

1. Congenital/Hereditary Causes

  • Marfan syndrome - Lens subluxation is usually superotemporal.
  • Homocystinuria - Lens dislocation is inferonasal.
  • Ehlers-Danlos syndrome - Can cause lens instability.
  • Weill-Marchesani syndrome - Lens dislocation often inferior.

2. Acquired Causes

  • Pseudophakia (complication of cataract surgery)
  • High myopia
  • Hyper mature cataract
  • Syphilis, Uveitis, Pseudoexfoliation syndrome

Types of Lens Displacement

  • Partial Subluxation: Lens remains partially attached to the zonules.
  • Complete Dislocation:
    • Anterior dislocation - Can cause acute angle-closure glaucoma.
    • Posterior dislocation - Can lead to vitreous inflammation and retinal detachment.

Clinical Features

  • Decreased vision
  • Monocular diplopia
  • Iris tremulousness (iridodonesis)
  • Lens shimmering (phacodonesis)
  • Acute pain and redness (if glaucoma develops)

Diagnosis

A. Slit-Lamp Examination
  • Detects iridodonesis and phacodonesis.
B. Gonioscopy
  • Checks for angle closure in anterior dislocation.
C. Retinal Examination
  • Indirect ophthalmoscopy to rule out retinal detachment.
D. Investigations
  • Ultrasound B-scan (for posterior dislocation)
  • OCT (for zonular assessment)
  • Genetic Testing (for syndromic cases)
  • Homocysteine levels (if homocystinuria is suspected)

Management

A. Conservative Management (For mild subluxation)

  • Spectacles or contact lenses (for refractive correction)
  • Mydriatics (e.g., Atropine 1%) (to relieve pupillary block)
  • Regular monitoring (if no complications)

B. Surgical Management

1. Anterior Dislocation

  • Emergency lens removal (ICCE or Pars Plana Lensectomy)
  • Intraocular Lens (IOL) implantation
    • Scleral-fixated IOL (SFIOL)
    • Anterior Chamber IOL (ACIOL)

2. Posterior Dislocation

  • Pars Plana Vitrectomy with Lensectomy
  • IOL implantation if needed

3. Management of Complications

  • Glaucoma → IOP-lowering medications, surgery
  • Retinal Detachment → Vitrectomy with repair

Key Points for Exams

  • Most common cause: Trauma
  • Superotemporal dislocation: Marfan syndrome
  • Inferonasal dislocation: Homocystinuria
  • Most serious complication: Secondary glaucoma
  • Treatment of choice for posterior dislocation: Pars plana vitrectomy with lensectomy