Ocular ultrasonography: A diagnostic key to solving the mystery of sudden unilateral blindness in a mare

Background: Sudden unilateral blindness in horses can arise from various ocular or neuro-ophthalmic disorders. This case report describes an acute right-sided blindness in a mare, where ocular ultrasonography revealed traumatic lens luxation secondary to chronic entropion-induced self-trauma, an unusual and diagnostically challenging presentation. Methods: A ۷-year-old Kochon mare named Rojina was referred with a recent onset of right-sided blindness. Clinical examination revealed a central corneal opacity consistent with chronic keratitis extending laterally. Comprehensive ophthalmic evaluation was followed by ocular ultrasonography using a ۱۰ MHz linear transducer to assess intraocular structures. The owner reported a history of chronic entropion and frequent eye rubbing against stable walls or hard surfaces, suggesting repeated self-inflicted trauma. Results: B-mode ultrasonography revealed complete posterior lens luxation, with the lens appearing as a well-defined hyperechoic structure floating freely within the posterior chamber. Multiple linear echogenicities consistent with vitreous hemorrhage were identified. The iris appeared thickened, and the ciliary bodies were detached from the lens capsule. Based on ultrasonographic and historical findings, a diagnosis of traumatic posterior lens luxation secondary to entropion-associated ocular trauma was made. The condition led to sudden and irreversible blindness, which gradually progressed to lens atrophy, increased opacity, and fibrotic degeneration. Given the fibrotic and deformed nature of the displaced lens, surgical correction was not feasible. Systemic therapy with the antibiotic (amikacin), NSAIDs (phenylbutazone), and the gastric protectant omeprazole, along with topical autologous serum eye drops (ASED), was administered to reduce inflammation and promote corneal healing. Conclusion: This case highlights the importance of thorough diagnostic imaging in equine ophthalmology, particularly when clinical signs and ocular lesions are inconsistent. Chronic entropion, by causing continuous ocular irritation and pruritus, can lead to persistent rubbing of the eye against hard surfaces such as stable walls. This repetitive trauma may ultimately result in complete lens luxation, leading to irreversible blindness. Early detection and management of entropion are therefore essential to prevent irreversible vision loss in horses.

کلیدواژه ها:

Lens luxation ، Equine ، Entropion ، Ultrasonography ، Blindness