Secondary Glaucoma

Question 1

What is the difference between Pseudoexfoliation Glaucoma (PXG) and Exfoliation Glaucoma.

Answer 1

In Exfoliation Glaucoma, HEAT causes damage to the cells on the anterior lens and causes it to ëxfoliate” where as in Pseudoexfoliation Glaucoma Fibrillar Proteinaceous substances are produced in high concentrations and ultimately deposits in the Trabecular Meshwork, affecting aqueous outflow.

Question 2

What are the risk factors for PXF/PXG?

Answer 2

-Age - Rarely occurs in people under 50
5 year risk is 5% and 10 year risk 15%
- Having PXF without glaucoma - 5-10x more likely to develop glaucoma
-Background - 50% of cases are of Scandinavian countries
- Gender - Women > Men
- Location - Living at HIgher Altitudes

Question 3

What are the Signs/Symptoms of PXG?

Answer 3

• PXF deposits on the pupil margin.
• Upon dilation, you will always see a 3 ring sign on the anterior capsule.
• Loss of iris pigment near the pupil.
• Gonioscopy shows pigment along Schwabes Line (Sampaolesi line - think of it as a shelf-dust scenario), and PXF will also be seen on the Iris Surface and Corneal Endothelium.
• Poor Pupillary response to dilation is a subtle finding. Assumed to be due to iris dilator muscle atrophy, and can mean there will be weak zonular attachments making cataract surgery more difficult.

Question 4

What Gene is associated with PXF and what is it responsible for?

Answer 4

PXF pxs have been found to have sequence variants in the LOXL1 Gene.

The LOXL1 Gene is responsible for the sequencing of elastin fibers .

Question 5

What is the Mechanism behind PXF?

Answer 5

Pathogenesis is unknown. Although attempts at identifying the material have been unsuccessful, pathologic study has revealed that the lens epithelium, trabecular meshwork, iris, ciliary processes, conjunctiva and periocular tissue are its source. The material is insoluble and floats in the aqueous humor, where it is filtered and deposited in the trabecular meshwork. Meanwhile local production of the proteinaceous material by the trabecular endothelial cells continues. All of this accumulates in the trabecular spaces and focally collapses Schlemm’s canal. This decreases aqueous humor outflow and increases IOP.

Question 6

What is the treatment for PXF/PXG?

Answer 6

Same as POAG.
however studies have shown the medical therapy isn’t as effective as it is with OAG, so surgical interventions are often used in conjunction.

Question 7

How does cataract surgery interfere with PXF/PXG diagnosis?

Answer 7

Cataract Surgery can often wash out the 3-ring sign. ALSO having PXF/PXG can make cataract surgery more difficult as it causes miosis due to weakened iris dilator muscles and lens zonules.

Question 8

What is included in the TRIAD for describing PG?

Answer 8

• Mid Peripheral Iris Transillumination
• Corneal Endothelial Pigment Deposits
• Diffuse or dense pigmentation of the angle.