Which of the following is NOT listed as a cause of lens luxation in horses?

• A. Trauma
• B. Uveitis
• C. Glaucoma
• D. Corneal ulceration

Answer: (D)

Lens luxation happens when the zonular fibers that suspend the lens are disrupted or weakened. In horses, this most often follows trauma to the eye, inflammatory damage from uveitis, or changes from glaucoma that put stress on or rupture the zonules. Corneal ulceration, while a serious ocular issue that can trigger pain and secondary inflammation, does not directly involve the zonular apparatus or the lens suspension, so it is not listed as a direct cause of lens luxation. If corneal disease leads to secondary glaucoma or severe uveitis, that could create conditions that predispose to luxation, but the corneal ulcer itself is not a primary cause.