Pseudoexfoliation Syndrome

From EyeWiki



Pseudoexfoliation Syndrome
Classification and external resources
DiseasesDB 31302


Pseudoexfoliation syndrome (PXF or PEX) is an age-related systemic syndrome that targets mainly ocular tissues through the gradual deposition of fibrillary white flaky material from the lens, mainly on the lens capsule, ciliary body, zonules, corneal endothelium, iris and pupillary margin.   Higher prevalence of open angle glaucoma in about 50% of these patients. 

Disease Entity

Exfoliation/Pseudoexfoliation syndrome is a systemic disease. It is most commonly noted in older individuals, typically over 50 years of age.

Disease

Exfoliation (pseudoexfoliation) Syndrome is characterized by the fibrillar deposits in the anterior segment of the eye. The deposits have been found on and in the subconjunctival tissue, pupillary margin, ciliary epithelium, lens epithelium, lens capsule, iris pigment epithelium, trabecular meshwork,cornea,zonules, orbital soft tissues, iris stroma and iris blood vessels. These deposits have also been found elsewhere in the body,including in the skin, heart, lungs, liver, kidneys, and elsewhere.[1] 

The disease may be bilateral by asymmetric.

It has been associated with myocardial infarction, cerebrovascular events and systemic hypertension.

Etiology

Etiology is unknown. It may a generalized disorder involving abnormal production or turnover of extracellular matrix in the basement membrane.

Risk Factors

  • Advance age over 70
  • Possible genetic prevalence
  • Its prevalence in different human populations especially, it is prevalent in Scandinavia.

General Pathology

The deposits are composed of elastic fibers (fibrillin and α-elastin)and noncollagenous basement membrane materials (laminin)which form fibrils. They are coated with the glycosaminoglycan hyaluroni acid.

Pathophysiology

Unclear, but  there is a gentic link to the gene LOXL1. In March 2008 of the American Glaucoma Society in Washington, D.C. Dr. Allingham. described a LOXL1 is a member of a family of enzymes that are active in the cross-linking of collagen and elastin in the extracellular matrix, he explained. “Because pseudoexfoliation syndrome is associated with abnormalities of the extracellular matrix and the basement membrane, this gene could reasonably play a role in the pathophysiology of the condition.”

Primary prevention

  • Routine annual eye exam by an ophthalmologist for the patients over ago 50.
  • Biomicroscopic examination(Slit Lamp) used by an eye doctor to examine the anterior lens capsule, pupillary dilation, intraocular pressure and optic nerve.
  • Treatment of elevated eye pressure with eye drops, laser or surgery.
  • Special precaution and awareness is essential prior and during cataract surgery.
    • Anterior chamber depth less than 2.5mm centrally could be an indication of zonular instability
    • Poor pupillary dilation
    • Zonular dialysis
    • Phacodonesis

All of the above may poses a significantly higher risk for intraoperative complications.

Diagnosis

Diagnosis is done by an eye exam using slit lamp and intraocular pressure exam. On regular routine exam an eye doctor could see a white fluffy material deposit on the anterior lens casule, and pupillary margin. Gonioscopy may show increase pigment deposit on the Trabecular Meshwork.

History

In 1971, a Finnish ophthalmologist John Linberg is the first doctor who described Pseudoexfoliation syndrome.  He reported the classic findings of white/grey flakes on the anterior lens capsule, glaucoma in approximately 50% of eyes, and an increasing prevalence of the condition with advancement of the age.  A few decades later, an American ocular pathologist named Georgiana Dvorak-Theobald suggested the term pseudoexfoliation to distinguish it from the true exfoliation syndrome. True exfoliation is caused by heat from glassblowing or infrared radiation exposure in the anterior lens capsule. It is characterized by "lamellar delamination of the lens capsule".

Physical examination

Poor pupillary dilation, transillumination defect on the pupilary borders, white fluffy deposits on the anterior lens capsule

Signs

  • Increased intraocular pressure
  • Poor dilation with peripupillary transillumination defect
  • fibrin white flaky deposits on the anterior lens capsule

Symptoms

No real symptom is associated with it, most of the finding are based on an eye exam.  The intraocular eye pressure elevation may not have symptom.

Clinical diagnosis

By an eye exam for patients over 50.

Diagnostic procedures

  • Slit lamp exam
  • Intraocular pressure check
  • Pupil check and transillumination exam
  • Dilated eye exam to check optic nerve
  • Gonioscopy to check for trabecular meshwork hyperpigmentation and open angle 

Laboratory test

  • Genetic test for a single mutation in the LOXL1
  • Check for Homocysteine level in tear film and plasma.  Scientists believe that elevated levels of plasma homocysteine are a risk factor for cardiovascular disease, and two studies have found higher levels of plasma and tear fluids homocysteine level in Psuedoexfoliation patients.

Differential diagnosis

  • LENS CAPSULE: True exfoliation
  • TRABECULAR MESHWORK HYPERPIGMENTATION/GLAUCOMA: Pigment dispersion,
  • IRIS TRANSILLUMINATION DEFECTS: Pigment dispersion

Management

  • Routine regular eye exam
  • Glaucoma treatment if the patient develops it
  • Special surgical precaution for cataract surgery pre-intra and post operation

Medical therapy

  • Eye drops if the patient has glaucoma
  • Use of Antioxidants 
  • Lower Homocysteine if the level is high in plasma or tear film

Medical follow up

Routine annual eye screening exam with dilation, if the patient has glaucoma then he/she needs 3-4 time per year eye exam.

Complications

  • Glaucoma or optic nerve cupping
  • Cataract surgery complications:
    • Drop nucleus or lens fragment
    • Zonular dialysis
    • Phacodonesis
    • Lens subluxation, either the natural lens or intraocular lens
  • Other systemic problems

Additional Resources

References

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