Fuchs heterochromic iridocyclitis (FHI) is a chronic unilateral uveitis appearing with the triad of heterochromia, predisposition to cataract and glaucoma, and keratitic precipitates on the posterior corneal surface.

However current plausible theories include infection with Toxoplasma gondii, Herpes simplex virus, Rubella, neurogenic causes, and autoimmune pathology.

One indication can be the Amsler sign, which is the presence of blood (hyphema) in the aspirated vitreous fluid, in paracentesis of the anterior chamber.

The sudden change of pressure in the anterior chamber upon suction induced by the paracentesis, or during cataract surgery, causes bursting of the fragile superficial iris capillaries resulting in micro-bleeding.

This is one clinical diagnostic sign of FHI slit-lamp examination shows stringy keratic precipitates Patients usually do not require treatment due to the benign nature of the disease.