What can cause a change in iris color or depigmentation in the iris (trauma, physical damage) ?

Iritis: Many conditions can cause iris pirgmentation as well as depigmentation. Trauma resulting in physical damage as well as due to chronic bleed may affect the coloration of iris. Some topical as well as systemic medications can also affect the iris color. Inflammation due to any cause as well as lack of neural input may also cause iris atrophy and discoloration in the form of hypopigmentation.

See below: Iris color change can be from congenital changes, trauma, chronic inflammation inside the eye or from certain medications. Changes to the outer cornea such as edema can also give the appearance of a different eye color.