Equine Image Quiz: A Percheron with ocular trauma
The forceful impact resulted in posterior lens luxation with secondary cataract formation (see the crescent-shaped opaque structure in the ventral aspect of the pupil). Detachment of the corpora nigra occurred after the trauma, and segments are seen floating in the anterior chamber (see brown circular structures in the pupil). Additional ocular changes include the presence of linear corneal band opacities that resulted from permanent defects of the Descemet's membrane in this normotensive eye (intraocular pressure was 20 mm Hg).
Trauma severe enough to cause lens displacement usually also induces severe uveal tissue damage leading to vision deficits or blindness as a result of retinal degeneration. In addition to severe trauma, other possible causes for acquired anterior or posterior luxation or subluxation of the lens in horses include cataract formation (primary or as a result of chronic uveitis), glaucoma, intraocular neoplasia, and endophthalmitis. Luxated lenses invariably become cataractous, and intracapsular lens extraction can be recommended in certain cases. Evisceration or implantation of an intrascleral silicone prosthesis is an alternative to lens removal in blind eyes with lens luxation.