Trabecular meshwork pigmentation is a manifestation of the clinical diagnosis of pigmentary glaucoma. Pigmentary glaucoma is a secondary open-angle glaucoma caused by pigmentation of the anterior segment of the eye. What are the clinical symptoms it can be confused with? Iris pigmentary loss There are no other conditions associated with iris spoke transillumination defects in PDS/PG. In patients with congenital glaucoma, some patients occasionally have a transillumination defect visible in the distal periphery of the iris near its attachment, but not in the form of a spoke. Patients with exfoliation syndrome occasionally have pigment spreading, and the transillumination defect is mostly located at the pupillary margin or in scattered patches throughout the iris. Damage to the posterior surface of the iris due to trauma or surgery presents as irregular patches of iris pigment loss. Patients with posterior iris depigmentation due to severe uveitis also present with a regional patchy loss of pigment, but not a peripheral whorl-spoke defect. Occasionally, there may be a marbled transillumination defect in a normal eye, but it is distinct from the changes seen in PDS/PG. Uveitis If small pigment particles are floating in the atrial water they can be mistaken for white blood cells and misdiagnosed as uveitis. To make a correct diagnosis, it is important to note the typical signs of PDS and the lack of other signs of uveitis, such as conjunctival congestion, KP, and posterior iris adhesions. loss of pigment on the posterior surface of the iris in patients with PDS does not provoke an inflammatory response, although phagocytes can advance into the iris stroma. Herpes zoster keratoconjunctivitis can cause fan-shaped iris atrophy, and herpes simplex keratoconjunctivitis can cause extensive iris atrophy. Neither has a PDS-like iris transillumination defect. Increased pigmentation of the trabecular meshwork Abnormal pigment dispersion can occur in eyes with syndromes other than PDS/PG. The pigment dispersion associated with exfoliation syndrome can lead to significant darkening of the trabecular meshwork. In many of these cases, the pigment mixes with the cystic membrane exfoliating material to form irregular, linen-like bands of pigment. A typical Krukenberg pike is not developed. The typical cystic membrane exfoliating material helps in the correct diagnosis. Patients with peripheral iris or ciliary body cysts occasionally have moderate pigmentation on the trabecular meshwork without a typical Krukenberg’s pike. Diagnosis is made with the aid of observation of the characteristic transillumination defect of the peripheral iris PDS Definitive diagnosis requires the application of an iridocorneal keratoscope under dilated pupil conditions to detect subiris cysts. In both of these cases there is no pigmentation on the posterior surface of the peripheral lens. Melanoma of the anterior and posterior segments Melanoma of the iris, ciliary body, or posterior segments (if the vitreous anterior membrane is ruptured) can be accompanied by pigmentation. Pigmented tumor cells or pigment-filled phagocytes can cause considerable darkening of the anterior and posterior chambers. However, the typical symptoms of PDS/PG are lacking: there is no Krukenberg shuttle and there is no transillumination defect. The primary tumor is easily detected. Inflammation of the posterior surface of the iris may occasionally be accompanied by moderate amounts of pigment release, often aggregated in clusters in the inferior atrial horn, along with signs of inflammation. Other Implantation of a posterior atrial IOL can sometimes cause PG, when the abnormally positioned posterior atrial IOL and the iris are in prolonged postoperative contact and friction resulting in pigment release. Exfoliation syndrome Mechanical friction between the peripheral lens and the peripupillary iris in pigmentary glaucoma, similar to pigmentary glaucoma with iris transmission defect Krukenberg’s shuttle, trabecular pigmentation and elevated intraocular pressure.