Image supplied by Rachel Dixon, Specsavers Maidstone, UK
Pigment deposition on the endothelium is most effectively assessed during slit lamp examination by focussing light directly onto the corneal endothelium.
Endothelial pigment can be observed in patients for several reasons.
It can be a sign seen in pigment dispersion syndrome whereby friction between the iris and lens zonules causes the release of iris pigment granules into the anterior chamber and onto the posterior corneal surface. The pigment commonly collects in a vertical line centrally, commonly known as a Krukenberg spindle. This sign is often seen in conjunction with iris transillumination and usually occurs bilaterally.
Endothelial pigment may be observed in anterior uveitis, usually in an irregular pattern and in association with cells and flare in the aqueous, keratic precipitates and peripheral anterior synechiae.
Less commonly, trauma or retinal detachment may also give rise to endothelial pigment deposition.
Progression & Prognosis
Although the presence of pigment on the endothelium does not commonly impact vision, it can be an indicator of certain conditions that require a comprehensive work up and further investigation.
Intraocular pressures should always be assessed due to the pathophysiology behind this sign. Aqueous currents can cause the pigment granules that are released in the anterior chamber to collect in the trabecular meshwork and block aqueous outflow, leading to raised intraocular pressure and subsequent risk for glaucoma. This can be assessed through gonioscopy.