Q. What is Sampaolesi’s line and its significance in PXFG?
A) A line of inflammation at the iris root
B) A pigment deposition anterior to Schwalbe’s line
C) A line indicating corneal edema
D) Pigmented rings in the peripheral cornea
Answer: B) A pigment deposition anterior to Schwalbe’s line
Explanation: Sampaolesi’s line is a characteristic finding in PXFG, described as pigment deposition anterior to Schwalbe’s line. It is commonly seen on gonioscopy.
👁️ AETIOLOGY OF PSEUDOEXFOLIATION (PXF) AND PSEUDOEXFOLIATIVE GLAUCOMA (PXFG)
🔬 1. Aetiology of Pseudoexfoliation Syndrome (PXF)
PXF is a systemic, age-related, extracellular matrix disorder characterized by the abnormal production and accumulation of fibrillogranular proteinaceous material within ocular and systemic tissues.
🧪 Pathogenesis Overview
- The material is amyloid-like and elastotic, primarily composed of:
- Fibrillin-1
- Fibulin
- Elastin
- Laminin
- Glycoproteins
- Cross-linked matrix proteins
🧬 Cellular Origins:
- Produced by nonpigmented ciliary epithelium, trabecular endothelial cells, lens epithelial cells, and iris pigment epithelium.
- Accumulates in:
- Anterior lens capsule
- Zonules
- Iris
- Corneal endothelium
- Trabecular meshwork
🧠 Underlying Mechanisms:
- Elastosis: Abnormal elastin fiber production and deposition
- LOXL1 gene mutation:
- LOXL1 (Lysyl Oxidase-Like 1) on chromosome 15q24 is essential for cross-linking collagen and elastin.
- Certain SNPs (e.g., rs1048661 and rs3825942) increase the risk of PXF development.
- Oxidative stress: Increased reactive oxygen species (ROS) and impaired antioxidant defenses
- Abnormal ECM remodeling: Dysregulated matrix metalloproteinases (MMPs) and tissue inhibitors (TIMPs)
⚠️ 2. Aetiology of Pseudoexfoliative Glaucoma (PXFG)
PXFG arises as a secondary open-angle glaucoma due to the mechanical obstruction of the trabecular meshwork (TM) by PXF material and pigment granules.
🧩 Mechanism of Glaucoma Development:
- Accumulated material obstructs aqueous humor outflow.
- Pigment dispersion from iris rubbing further clogs TM.
- TM endothelial cells degenerate and lose phagocytic activity.
- Outflow resistance rises → increased intraocular pressure (IOP).
- Resultant optic nerve damage and retinal ganglion cell loss lead to glaucomatous visual field defects.
PXFG is more aggressive than primary open-angle glaucoma (POAG), with higher peak IOP, wider fluctuations, faster optic nerve damage, and worse visual prognosis.
👁️ CLINICAL PRESENTATION OF PXF AND PXFG IN THE EYE
🔎 A. Slit-Lamp and Anterior Segment Findings (PXF)
| Feature | Description |
|---|---|
| Anterior lens capsule deposits | Classic “target sign”: Central disc, clear intermediate zone, peripheral granular ring with radial striae |
| Iris transillumination defects | Moth-eaten appearance, especially at pupillary border |
| Poor pupil dilation | Due to rigid, atrophic iris |
| Pigment dispersion | On corneal endothelium, lens zonules, and angle |
| Zonular instability | Can result in phacodonesis, lens subluxation, or intraoperative complications during cataract surgery |
| Krukenberg spindle | Vertical pigment deposition on corneal endothelium (may overlap with pigment dispersion syndrome) |
🔬 B. Gonioscopic Findings
| Finding | Explanation |
|---|---|
| Sampaolesi’s line | A pigmented line anterior to Schwalbe’s line, commonly seen in PXF |
| Angle pigmentation | Dense, irregular pigment in trabecular meshwork |
| Open angles | PXFG is an open-angle glaucoma, unlike angle-closure types |
| PXF material in angle structures | May be visible on gonioscopy with high magnification |
🔍 C. Fundoscopic and Optic Nerve Findings (PXFG)
| Feature | Description |
|---|---|
| Optic disc cupping | Increased cup-to-disc ratio, often asymmetrical |
| Neuroretinal rim thinning | Especially superior and inferior rim loss |
| Disc hemorrhages | May precede progression |
| Peripapillary atrophy | Common with chronic PXFG |
| More advanced cupping at presentation | PXFG often discovered late due to asymptomatic IOP spikes |
🔬 D. Visual Field Defects
- Similar to POAG but often:
- More severe at diagnosis
- Faster progression
- Common field defects:
- Paracentral scotomas
- Nasal steps
- Arcuate scotomas
- Generalized depression (late)
📈 PXF vs PXFG Summary Table
| Feature | PXF | PXFG |
|---|---|---|
| Definition | Systemic elastotic disorder with ocular material deposition | Secondary open-angle glaucoma due to TM obstruction from PXF |
| IOP | Usually normal | Elevated, fluctuating, often >30 mmHg |
| Laterality | Unilateral early, often progresses to bilateral | Typically develops in the eye with greater PXF burden |
| Angle | Open, heavily pigmented | Open, often with Sampaolesi’s line |
| Optic nerve | Normal initially | Cupping, rim thinning, hemorrhages |
| Visual field | Normal early | Glaucomatous defects; often worse than POAG |
| Treatment | Observation, monitoring | Requires IOP-lowering meds, laser, or surgery |
🧠 Key Points to Remember
- PXF is the precursor to PXFG and should be monitored regularly.
- PXFG has a higher IOP at diagnosis, poorer medication response, and faster progression than POAG.
- Early diagnosis of PXF (by slit lamp and gonioscopy) can prevent late-stage vision loss.
- Always check both eyes, as the disease is asymmetric but often bilateral.