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PXF in opthalmology

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pseudoexfoliation syndrome glaucoma

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Pseudoexfoliation Syndrome (PXF / PXS) in Ophthalmology

Definition

Pseudoexfoliation syndrome (PXF or PXS) is an age-related systemic disorder characterised by the production and progressive accumulation of a grey-white fibrillary extracellular material in ocular and non-ocular tissues. It is the most common identifiable cause of secondary open-angle glaucoma worldwide and a leading cause of glaucoma blindness. The glaucoma that results is called pseudoexfoliation glaucoma (PXG) or "capsular glaucoma."
  • Wills Eye Manual, p. 595 | Kanski's Clinical Ophthalmology 10th ed., p. 397

Epidemiology

FeatureDetail
AgeRare before 50; prevalence increases rapidly after the 6th decade; ~5% prevalence at age 75-85
SexMore common in women
GeographyHighest prevalence in Scandinavia; found worldwide in all ethnic groups
Glaucoma risk15-30% have glaucoma at time of PXF diagnosis; cumulative risk requiring glaucoma treatment can reach 60% at 5 years
LateralityUsually bilateral but often asymmetric; glaucoma confined to one eye in ~two-thirds of patients

Pathogenesis

Pseudoexfoliative material is a grey-white fibrillary substance arising from abnormal extracellular matrix (ECM) metabolism. Key points:
  • Deposited on: lens capsule, zonular fibres, iris, trabecular meshwork (TM), conjunctiva, and distant visceral organs (skin, heart, liver)
  • Genetic basis: Single nucleotide polymorphisms (SNPs) in the LOXL1 gene (chromosome 15), which encodes lysyl oxidase-like 1, an enzyme vital for tropoelastin and collagen cross-linking and ECM maintenance. These SNPs are nearly universal in PXF patients in some populations, but are also common in individuals without PXF.
  • Elevated homocysteine in plasma and aqueous humour is associated; inadequate dietary folate (which reduces homocysteine) may be a risk factor.
  • IOP elevation results from trabecular obstruction by PXF material and liberated iris pigment, causing secondary degenerative outflow dysfunction.
Diagram of PXF material (A) accumulating and (B) depositing in the trabecular meshwork
Diagrams (A & B from Kanski's) illustrating how PXF fibrillary material accumulates in the anterior segment angle and clogs the trabecular meshwork.
Diagram B of material in the angle

Clinical Signs

Slit Lamp (Critical Signs)

1. Anterior lens capsule - the classic "target pattern":
  • Central zone: disc of PXF material (often with rolled-up edges)
  • Mid-zone (clear zone): the iris rides over and wipes away PXF material during pupillary movement
  • Peripheral cloudy zone: PXF deposits here undisturbed
Pupil dilation is often needed to visualise the full anterior lens capsular pattern.
Classic PXF "target pattern" on anterior lens capsule - slit lamp view showing white flaky material at pupil margin and peripheral zone
Fig: PXF material on anterior lens capsule (Kanski's) - note the white scrolled deposits at the peripheral zone boundary.
2. Pupillary margin:
  • White, flaky PXF material visible at the pupillary border
  • Peripupillary transillumination defects (TIDs) - from iris pigment loss at the sphincter region
PXF with white material at pupillary margin
Fig 9.11.1 (Wills Eye): White PXF material at the pupillary margin with peripupillary iris transillumination defects.
3. Iris:
  • Poor pupillary dilation (believed to be due to iris dilator muscle atrophy)
  • Peripupillary iris atrophy
Poor pupil dilation with iris TIDs in PXF
Fig 9.11.2 (Wills Eye): White material on the anterior lens capsule of a dilated PXF eye.

Gonioscopy (Angle Signs)

  • Heavy, irregular trabecular pigmentation - especially inferiorly (more than in pigment dispersion)
  • Sampaolesi line: an irregular pigment band on or anterior to the Schwalbe line, especially inferiorly - present but not pathognomonic (also seen in pigment dispersion syndrome)
  • Dandruff-like PXF material deposits on trabecular meshwork
  • Increased risk of secondary angle closure due to zonular laxity

Other Slit-Lamp Signs

  • PXF material on the corneal endothelium (angular, irregular KP-like deposits); endothelial cell density is lower than normal
  • Phacodonesis (lens tremulousness) from zonular weakness
  • Cataract formation (more common - possibly from reduced aqueous ascorbate)
  • Zonular fragility - spontaneous lens subluxation is rare, but surgical risk is high

IOP Characteristics

  • PXF is associated with highly volatile IOP with large diurnal fluctuations
  • IOP may rise acutely despite an open angle (mimicking acute angle closure)
  • IOP levels tend to be higher than in POAG

Prognosis

Key teaching point: Pseudoexfoliation glaucoma progresses more rapidly than primary open-angle glaucoma (POAG) and is more likely to result in significant visual loss. Severe damage may be present at diagnosis and can develop very rapidly.
  • Kanski's Clinical Ophthalmology, p. 398

Systemic Associations

  • High-tone sensorineural hearing loss
  • Ischaemic cardiovascular and cerebrovascular disease
  • Increased risk of pelvic organ prolapse in older women
  • Elevated plasma homocysteine

Differential Diagnosis

ConditionDistinguishing Features
Pigment dispersion syndromeMid-peripheral iris TIDs (not peripupillary); pigment on posterior lens equator; deep anterior chamber; typically young myopes; Krukenberg spindle on cornea
True capsular exfoliationTrauma or chronic heat exposure (glassblowers); thin membrane peels from anterior capsule; glaucoma uncommon
Inflammatory glaucomaPhotophobia, flare; ragged "volcano-like" PAS; no PXF material
Primary amyloidosisAmyloid deposits at pupillary margin/anterior capsule; systemic features
UGH syndromePrior intraocular surgery history

Workup

  1. History: Family history; age; ethnicity
  2. Slit-lamp examination: Look for PXF material at pupillary margin; dilate pupil to assess anterior lens capsule
  3. Gonioscopy: Assess pigmentation pattern, Sampaolesi line, angle width
  4. Baseline glaucoma evaluation: IOP (including diurnal curve), optic disc assessment, visual fields, OCT RNFL

Treatment

Medical

  • Similar to POAG - prostaglandin analogues are first-line
  • Medical therapy fails more commonly than in POAG; IOP control is often more difficult

Laser

  • Selective Laser Trabeculoplasty (SLT) is more effective in PXF than in POAG, with mean IOP reduction ~30%
  • Caution: trabecular hyperpigmentation causes higher laser energy absorption - risk of transient IOP spikes
  • SLT benefit may wane after ~2 years

Surgical

  • Phacoemulsification alone can significantly lower IOP but carries high complication risks:
    • Poor mydriasis (difficult to dilate)
    • Zonular fragility and weakness - risk of zonular dehiscence
    • Increased risk of intraoperative vitreous loss
    • Postoperative IOP spikes, corneal oedema, inflammation, capsular opacification, and IOL dislocation
  • Combined phaco + trabeculectomy for better IOP control
  • Cataract extraction does NOT eliminate the glaucoma

Follow-Up

Patient groupInterval
PXF with glaucomaEvery 1-3 months (as with POAG, but with awareness of rapid progression)
PXF without glaucomaEvery 6-12 months; treat at first sign of IOP elevation or glaucomatous damage

Recent Evidence (2025)

A 2025 systematic review and meta-analysis (PMID 40131012) examined OCT alterations of the choroid and lamina cribrosa in PXF and PXG, providing new structural insights into how PXF affects deep optic nerve head architecture - relevant for understanding the aggressive progression of PXG beyond just IOP effects.
Sources: Kanski's Clinical Ophthalmology: A Systematic Approach (10th ed.), pp. 397-399 | The Wills Eye Manual (7th ed.), pp. 595-598
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