Secondary Glaucoma: NBEO/OKAP Guide
Master secondary glaucoma mechanisms, causes and board pearls for NBEO and OKAP with this focused clinical review for eye care trainees.
Which combination of findings is most typical of pigment dispersion syndrome?
Secondary Glaucoma in 30 Seconds
Secondary glaucoma occurs when an identifiable ocular or systemic condition raises intraocular pressure and damages the optic nerve. This differs from primary glaucoma, where no causative disease is found. Recognizing the underlying cause changes treatment and matters heavily on NBEO and OKAP.
How Secondary Glaucoma Differs from Primary
In secondary glaucoma, a specific disease process disrupts aqueous outflow or angle anatomy and drives the IOP rise. Primary glaucoma has no such identifiable cause. Secondary glaucomas fall into two broad mechanisms. Open-angle secondary glaucomas increase resistance at the trabecular meshwork while the angle remains open. Secondary angle-closure glaucomas involve a mechanical or pathologic process that pushes the iris into the angle or blocks aqueous flow. Board exams test whether you can match the mechanism to the clinical picture and then predict the correct management.
Common Causes by Mechanism
Open-angle secondary glaucomas (increased outflow resistance):
- Pigmentary glaucoma: pigment dispersion syndrome, Krukenberg spindle, iris transillumination defects, reverse pupillary block
- Pseudoexfoliation glaucoma: exfoliation material deposits on the lens and trabecular meshwork, zonular weakness, often produces higher IOP fluctuations and peak pressures than primary open-angle glaucoma
- Steroid-induced glaucoma: corticosteroids increase extracellular matrix deposition and reduce trabecular meshwork outflow, partly through glycosaminoglycan accumulation and altered trabecular cell function
- Neovascular glaucoma: early disease is open angle because a fibrovascular membrane covers the trabecular meshwork; progressive membrane contraction produces peripheral anterior synechiae and secondary angle closure
- Uveitic glaucoma: inflammatory cells, protein, trabeculitis and peripheral anterior synechiae impair aqueous outflow
- Angle recession glaucoma: follows blunt trauma with a widened ciliary body band on gonioscopy; may present years after the injury
Secondary angle-closure glaucomas:
- Phacomorphic glaucoma: a swollen lens pushes the iris forward
- Plateau iris: an anteriorly positioned ciliary body crowds the angle
- Aqueous misdirection (malignant glaucoma): aqueous is redirected posteriorly, pushing the iris-lens diaphragm forward
4 Facts Exams Always Ask
- Pseudoexfoliation syndrome is the most common identifiable cause of secondary open-angle glaucoma worldwide.
- The Krukenberg spindle is a vertical band of pigment on the corneal endothelium, a classic sign of pigment dispersion syndrome.
- A steroid responder shows an IOP rise after corticosteroid exposure because extracellular matrix accumulates in the trabecular meshwork and reduces outflow. This response is reversible if the steroid is stopped early.
- Pseudoexfoliation causes zonular weakness, raising the risk of lens subluxation and complications during cataract surgery.
The Classic Trap
The most common exam mistake is treating every glaucoma the same way and missing the underlying cause. A second frequent trap is confusing pigmentary glaucoma with pseudoexfoliation glaucoma, since both involve pigment liberation and open-angle disease. Identifying the true secondary cause changes management. Neovascular glaucoma needs anti-VEGF therapy and panretinal photocoagulation, not just IOP-lowering drops. Phacomorphic glaucoma needs lens extraction, not long-term medical therapy.
Clinical Pearl
Any patient on chronic corticosteroids, whether topical, systemic or intranasal, needs periodic IOP monitoring because a subset of the population are steroid responders. This response can develop weeks after starting therapy and is reversible if the steroid is stopped early. Steroid response is more likely in patients with POAG, high myopia, diabetes or a family history of glaucoma.
Checkpoint 1
Which patient is at increased risk for a significant steroid-induced IOP rise?
Checkpoint 2
Which slit-lamp finding is most characteristic of pseudoexfoliation syndrome?
A 68-year-old man presents with mild blurred vision. Slit lamp exam shows a vertical pigment band on the corneal endothelium and transillumination defects in the iris. IOP is 28 mmHg in both eyes. Gonioscopy shows an open angle with dense trabecular pigmentation.
After blunt ocular trauma, which angle finding is associated with later development of angle-recession glaucoma?
Sources & Reviewer Info
Diagram created with AI image generation, clinically reviewed for accuracy.
References
- American Academy of Ophthalmology. Basic and Clinical Science Course, Section 10: Glaucoma.
- Shields' Textbook of Glaucoma.
- American Academy of Ophthalmology. EyeWiki: Secondary Glaucoma.
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