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. Any other eye disease with pigmentation of the anterior segment must be differentiated from “primary” PDS. The different sources and mechanisms of pigmentation may require different management. Inflammation of the anterior segment of the eye, cysts, tumors, trauma, and intraocular surgery and laser treatment can all lead to loss of iris pigment granules, causing pathologic changes similar to PDS. The following are the tests that need to be done to identify 1. iridocyclitis Most acute inflammation of the iridociliary body will have symptoms or discomfort such as eye redness, eye pain, photophobia, or vision loss, unlike patients with PDS, who have almost none of these clinical symptoms and will only have vision loss, sometimes with eye distention and discomfort, when combined with glaucoma in advanced stages. The anterior chamber glow is a common clinical sign of iridocyclitis and is a “barometer” of the severity of the inflammation, but patients with PDS rarely have anterior chamber glow. Chronic iridocyclitis is associated with anterior and posterior adhesions of the iris, with lambdoid and dusty posterior corneal deposits (KP) and floating cells in the anterior chamber. Deposits of pigment granules in the posterior iris recess and anterior surface are usually absent. History taking and slit lamp examination can identify. 2. iris or ciliary body cysts and tumors The above lesions can cause iris depigmentation and deposition of pigment granules in the anterior segment, with features similar to the pigment spreading process and chronic onset in patients with PDS, but KP is mostly diffuse and rarely has a vertical spindle shape. Cysts or tumors on the iris surface are easily detected and diagnosed under slit lamp, and cysts and tumors on the iris stroma or even the posterior surface and ciliary body can be differentiated on UBM examination. 3. Post-trauma, laser, and surgical pigmentation of the anterior segment Patients who have undergone these treatments have a clear history of treatment, as well as other ocular lesions and abnormalities, and pigmentation is not uniformly deposited on the trabecular meshwork but is phasic, and is often most evident below. IOL implantation has a low incidence of pigment dispersion, in most cases due to implantation of the IOL into the ciliary sulcus or an unstable IOL position that brings the optical portion or loop into contact with the iris pigment epithelium and results in pigment dispersion. The detached pigment granules in such patients are coarser than those in patients with PDS, with large pigment granules deposited and more uniformly visible behind the cornea, in the atrial water and even on the iris surface and IOL surface, and the lower atrial angle can be covered by a large number of detached pigment granules, while pigment granule deposition in the trabecular meshwork in other quadrants is relatively light, which is uncommon in patients with PDS.