Abnormalities of the corpora nigra can include which of the following?

• A. Cysts: congenital or acquired
• B. Glaucoma
• C. Retinal detachment
• D. Conjunctival edema

Answer: (A)

Abnormalities of the corpora nigra are cystic lesions that can be present from birth or develop later in life. In the horse, the corpora nigra are dark iris nodules near the pupil, and cysts can form within these structures, sometimes protruding into the pupil or appearing as small sacs. This is why congenital or acquired cysts are the typical abnormality associated with the corpora nigra. The other conditions listed—glaucoma, retinal detachment, and conjunctival edema—affect different parts of the eye (intraocular pressure, posterior segment, and the ocular surface or adnexa, respectively) and do not reflect pathology of the corpora nigra itself.