Secondary Glaucomas

Pigment Dispersion Syndrome

In pigment dispersion syndrome, the posterior iris surface rubs against the anterior lens zonules, a mechanical contact called reverse pupillary block. Pigment granules shear off the iris pigment epithelium with each blink and pupillary movement, circulate in the aqueous, and settle into the trabecular meshwork. The meshwork's outflow capacity is finite. Once accumulated pigment overwhelms it, IOP rises and the result is a secondary open-angle glaucoma: pigmentary glaucoma.

Pseudoexfoliation Syndrome

Pseudoexfoliative material is a fluffy, white, fibrillar substance resembling amyloid, produced by abnormal extracellular matrix turnover. It deposits on the lens capsule, the pupillary margin, and the trabecular meshwork, producing the same secondary open-angle mechanism seen with pigment dispersion. It also weakens the lens zonules independently of that meshwork effect, which is why zonular instability during cataract surgery is a recognized risk in these patients.

The syndrome also shows striking geographic variation, with the highest reported rates in Scandinavian and other Nordic populations. Prevalence climbs steadily with age. Pseudoexfoliation glaucoma tends to run a rougher course than primary open-angle glaucoma at a comparable starting pressure, with higher peak IOP, wider diurnal swings, and faster visual field progression, so many clinicians set a lower target pressure for these patients from the start.

Phacolytic vs. Phacomorphic Glaucoma

These two are easy to conflate, but they are mechanistically opposite. Phacolytic glaucoma is a leak: a hypermature cataract lets high-molecular-weight lens proteins escape through an intact but permeable capsule, and macrophages that engulf that protein clog the trabecular meshwork. The result is open-angle. Phacomorphic glaucoma is a squeeze: a large, swollen (intumescent) cataractous lens physically pushes the iris forward and narrows the drainage angle. The result is angle-closure, not open-angle. Same organ, opposite pathophysiology.

A third lens-induced route, lens particle glaucoma, needs a torn capsule rather than a leaky one. Trauma or cataract surgery that leaves solid cortical fragments behind lets those fragments drift into the anterior chamber, where they jam the trabecular meshwork directly and stir up a secondary trabeculitis on top of the blockage. The angle stays open, just like phacolytic glaucoma, but the culprit is visible lens debris rather than dissolved protein.

Glaucoma can also follow cataract surgery that goes smoothly, with no retained lens material or torn capsule in sight. This form, often labeled pseudophakic or aphakic glaucoma, is almost always open-angle. It tends to show up months to years after surgery, not right away. Proposed mechanisms overlap rather than compete: trabecular meshwork obstruction by inflammatory debris, subtle synechiae formation, and steroid-induced pressure elevation from the postoperative drop regimen itself. Because no single mechanism explains every case, it is worth ruling out before a pseudophakic patient with new open-angle glaucoma gets labeled as simply having developed POAG.

Neovascular Glaucoma

The classic driver is diabetic retinopathy: ischemic retina produces VEGF, which diffuses forward into the anterior segment and drives new vessel growth across the iris and angle. Those new vessels physically obstruct the trabecular drainage angle, and the iris itself can take on a "whorled" appearance from the same ischemia-driven neovascularization, a finding called rubeosis iridis. Neovascular glaucoma is one of the more aggressive and treatment-resistant forms of secondary glaucoma. Controlling IOP is not enough; the underlying retinal ischemia has to be addressed as well, typically with panretinal photocoagulation or anti-VEGF injection.