POAG has no obvious and universal signs that can be detected using biomicroscopy. However, certain signs are associated with secondary forms of glaucoma. Pigmentation on the corneal endothelium (e.g., Kruckenberg’s spindle), peripheral transillumination of the iris, and increased pigment in the trabcular meshwork may indicate pigmentary dispersion glaucoma.

Figure 1. Corneal endothelial pigment dusting (Kruckenberg’s spindle).

Grey flake-like material on the anterior lens capsule in a target pattern (i.e., a central disc and peripheral ring with an intervening clear area), and loss of pupillary ruff pigment may indicate pseudoexfoliative glaucoma.Pseudoexfoliation should not to be confused with true exfoliative material occasionally seen with 'glassblowers' cataract. Pseudoexfoliative glaucoma is more common in patients of Northern European/Scandinavian ethnicity.

Figure 2. Pseudoexfoliation of the anterior lens capsule.

A difference in color between the irides (iris hetereochromia) may warn of a unilateral glaucoma. Iris neovascularization (rubeosis iridis), usually secondary to diabetes or vascular occlusion, may indicate neovascular glaucoma.Iris synechiae can accompany uveitic or inflammatory glaucoma. Pupillary corectopia (irregular-shaped pupil) and/or pupillary dialysis (breakage of the iris root connection to the ciliary body) can be associated with fibrotic or neovascular changes in the anterior chamber angle, or it can result from a prior injury, potentially resulting in traumatic (angle recession) glaucoma.

Figure 3. Iris neovascularization (rubeosis iridis).

A narrow anterior chamber, and/or a hazy, ‘steamy’ cornea with perilimbal injection suggests angle closure glaucoma. Opacities in the anterior lens cortex (glaucomflecken) may also result from highly elevated intraocular pressure associated with angle closure glaucoma or malignant glaucoma secondary to cataract surgery complication.

Figure 4. Acute angle closure glaucoma.

As an interesting side-note, highly elevated pressures from glaucomatocyclic crisis (Posner-Schlossman Syndrome) tend to show no markedly obvious biomicroscopic findings except for mild anterior uveitic signs. This rare condition typically affects young male adults, of which 40% are positive for white blood cell component HLA-Bw54. These patients may be completely asymptomatic.(5)

Figure 5. Glaucomflecken (Schiemflug photo).

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