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Topic:Ophthalmology
Ophthalmology in horses encompasses the study and treatment of eye disorders and diseases affecting equine species. Equine ophthalmic conditions can range from conjunctivitis and corneal ulcers to more complex issues such as uveitis and cataracts. These conditions can impact a horse's vision and overall well-being. Diagnostic techniques in equine ophthalmology include visual examinations, fluorescein staining, and advanced imaging methods like ultrasonography. Treatment approaches vary depending on the specific condition and may involve medication, surgical intervention, or supportive care. This page compiles peer-reviewed research studies and scholarly articles that explore the anatomy, pathology, diagnostics, and treatment modalities related to equine ophthalmology.
Ocular cosmetic and prosthetic devices. Specific details on surgical procedures, although not covered here, are available in other references. Factors enhancing the overall cosmetic appearance obtained with procedures are emphasized, providing information that should allow veterinarians to offer clients a good cosmetic appearance and effective treatment for disfiguring ocular problems in their horses. Questions regarding procedures should be addressed to your referral ophthalmologist or, in the case of a corneoscleral prosthesis, the ocularist assisting.
Diagnosis and treatment of lens diseases. The lens represents a unique tissue in light of its embryologic development, retention of old cells and nuclear make-up, transparent nature, immune privileged status, and metabolic restrictions. Disorders of malformation and malposition occur, but cataract development is the most common and significant problem for owners and animals. Technologic and pharmacologic advances have allowed surgical removal of equine cataracts to become an acceptable alternative, capable of returning a visually impaired horse to a functional status. Uveal inflammation represents the greatest threat to successful sur...
Ocular neoplasia. Except for two neoplasms, notably SCC and sarcoid, ocular and periocular tumors are uncommon in horses. The practitioner must accurately determine the type of tumor by histopathology so appropriate treatment and a legitimate prognosis can be offered. The first attempt at treatment has the greatest chance to result in a cure; an aggressive treatment regimen therefore should be selected from the start.
Eyelid and nasolacrimal disease. An understanding of normal structure and function of the equine eyelid is essential to make an accurate diagnosis and appropriately treat equine eyelid diseases. Entropion, eyelid trauma, neoplasia, and nasolacrimal disorders are reviewed. Methods of diagnosis and treatment are presented.
Normal equine ocular anatomy and eye examination. When compared with small domestic animals, the horse has unique ocular characteristics (complete bony orbit, well-developed eyelid muscles, a nasal and temporal gray limbal line, granulae iridica, paurangiotic fundus). Knowledge of normal equine ocular anatomy is essential for ocular lesion interpretation. It is important to obtain a full history and general examination before sedation, nerve blocks, or other diagnostic ophthalmic tests are performed. All ocular examinations should include a systematic evaluation of both the anterior and posterior segments. Selection of other diagnostic tests ...
Medical evaluation of the eye relevant to purchase. Performance and pleasure horses depend upon their ability to see and assess the environment. Thus, the veterinarian must be able to examine the eyes and recognize abnormalities so that the owner or purchaser can be informed about the visual status and prognosis for the horse's vision. If the veterinarian encounters suspicious or abnormal findings during the examination, a more detailed examination and/or referral to a veterinary ophthalmologist can be recommended to the owner or purchaser.
Comparison of applanation tonometers in dogs and horses. Two Mackay-Marg tonometers and 2 Tono-Pen tonometers were evaluated in eyes in which intraocular pressure (IOP) had been altered and measured by use of a manometer. Eyes of anesthetized dogs and enucleated horse eyes were used. Compared with the manometer, none of the tonometers accurately measured IOP over the range between 0 and 100 mm of Hg. However at manometer measurements from 0 to 30 mm of Hg, several of the tonometers accurately measured IOP. In addition, significant differences were observed when the measurement accuracy of one tonometer was compared with that of another, especially a...
[Two rare lens abnormalities in horses]. Coloboma and ectopia of the crystalline lens are rarely encountered or diagnosed congenital defects of the equine eye. The clinical and ophthalmoscopic features of a congenital coloboma of the lens in a 3 year old Hanoverian stallion and of an ectopic lens in a 6-month old Hanoverian filly are described and depicted. In the stallion, the lens coloboma was associated with a partial coloboma of the zonules, and in the filly, the ectopic lens was small and spherical (microphakia, spherophakia) and associated with syneresis of and small floaters in the vitreous. Although it cannot be excluded that...
Immunotherapy of periocular squamous cell carcinoma with metastasis in a pony. A 5-year-old Pony of America mare was referred for evaluation of inflamed upper and lower right eyelids. Squamous cell carcinoma of the eyelids and ulcerative keratitis secondary to self-trauma were diagnosed. Initial treatment of the eyelid neoplasia with 2 applications of cryotherapy failed to resolve the lesions, and immunotherapy with bacillus of Calmette-Guerin (BCG) was instituted. Multiple injections of BCG over a 17-week period resulted in progressive shrinkage of the tumor mass, but regional metastasis to the ipsilateral submandibular lymph node occurred. Six months later, ocular neop...
Chlamydia psittaci infection in horses: results of a prevalence survey and experimental challenge. Nasal and conjunctival swabs were obtained from 300 horses and Chlamydia psittaci was isolated from 15 of them (5 per cent). Eleven nasal swabs and six conjunctival swabs were positive on culture, but there was no association between the isolation of the organism and the presence of clinical ocular or respiratory disease. Six ponies were challenged with an equine isolate of C psittaci into the eye, nasal cavity or bronchial tree. The organism could be isolated from nasal and conjunctival swabs taken from the ponies for up to 17 days after challenge, but there was no clinical evidence of diseas...
Evaluation of zones of iris hypoplasia in horses and ponies. Mass-like lesions of the iris were evaluated in 15 horses or ponies of various ages and breeds. Breed or gender predilection was not found. These lesions were most often found in blue irides at the 12 o'clock region. Because the lesions transilluminated and changed shape rapidly with changes in pupillary size, they were hypothesized to be zones of iris hypoplasia. Histologic evaluation of one specimen supported this interpretation. The lesions were not associated with any other ocular or systemic abnormality.
[Lens-induced uveitis (endophthalmitis phakoanaphylactica) in domestic animals]. In this paper ophthalmological and clinical results as well as the literature on lens-induced uveitis (LIU), a relatively unknown pathological syndrome in domestic animals, are presented. Out of all ocular material sent to the Institute of Pathology, GSF, from 1970 until 1990 (n = 864), 40 individual cases of LIU (14 cases in dogs, 13 in cats, 10 in rabbits, 1 in a horse and 2 in birds) were diagnosed. The histology of the eyes of the cases is characterized by a lesion of the lens capsule and a consequent reactive phacogenic inflammation of the anterior segment of the eye in the region of the ...
Ophthalmic procedures and surgery in the standing horse. Although many ophthalmic procedures can be performed on the standing horse, the decision to perform a procedure under sedation rather than general anesthesia must be made on the basis of the temperament of the horse, severity of the injury, and skill of the veterinarian. For example, veterinarians who are not comfortable with small suture material may find accurate repair of an eyelid laceration easier after general anesthesia rather than attempting to handle this suture in a moving patient. Correct use of nerve blocks and topical anesthesia will greatly facilitate examination, diagnosis, and ...
Anterior uveal melanoma, with secondary keratitis, cataract, and glaucoma, in a horse. Intraocular melanoma was diagnosed in a 13-year-old horse. Secondary clinical findings included keratitis, cataract, and glaucoma. The eye was enucleated. Follow-up information did not give an indication of metastatic disease.
[Clinical case report: unilateral malformation of the eye of a thoroughbred foal]. A unilateral malformation of the eye of a thoroughbred foal is described. The specific form of the tiny lens we named, "lenticulus". It is correlated with a maximal unchangeable mydriasis. The bulb shows physiological size. A brown-black pigmented mass inhibited (internal) inspection and examination of the middle and rear part of the eye. Special emphasis is laid on the insecure behaviour of the foal. A connection with an iridocyclochoroiditis, which was treated in the mare about a year ago, and the pathological changes in the eye of the foal is not evident.
Squamous cell carcinoma as a cause of dyspnea and blindness in a horse. An 8-year-old Quarter Horse mare was examined for chronic nasal discharge and obstruction of both nasal passages. A solid mass lesion was identified in the maxillary sinuses, soft palate, nasal and pharyngeal cavities. Palliative surgery was used to debulk the lesion and facilitate nasal airflow. Squamous cell carcinoma was diagnosed from surgical biopsies. Approximately 7-8 weeks after surgery, the mare was observed to be acutely blind. Ophthalmologic examination revealed central origin blindness and active retinitis. The squamous cell carcinoma had reobstructed the nasal passages. Pressure b...
Use of phacofragmentation for cataract removal in horses: 12 cases (1985-1989). The medical records of 12 horses that had cataracts removed by use of phacofragmentation were reviewed. Cataracts were removed from 16 eyes in horses ranging in age from 2 months to 15 years. Complications after surgery included corneal ulcers in 13 eyes, diffuse corneal edema in 5 eyes, and uncontrollable uveitis in 3 eyes. Follow-up information was obtained in all horses from 1 month to 3.5 years after surgery. Visual results were judged good by owners or veterinarians in 10 of the horses.
Mycotic keratitis in a horse caused by Aspergillus fumigatus. The first reported case in Finland. The first identified Finnish case of equine mycotic keratitis caused by Aspergillus fumigatus is described. The clinical picture, the sampling method, the macro- and micromorphology of the causative fungus and the therapy applied are reported in detail. Therapy with natamycin (Pimafucin 2.5% eyedrops. Gist-Brocades) was successful. Mykotisk keratit hos häst orsakad av beskrivs första gången i Finland. Klinisk bild, provtagning, makroskopisk och mikroskopisk morfologi av svampen samt terapi rapporteras i detalj. Terapin med natamycin (Pimafucin® 2.5 % ögondroppar, Gist-Brocades) var effek...
Bilateral colobomas involving the optic discs in a quarterhorse. THIS report describes bilateral colobomas of the optic discs with associated aberrations in ocular differentiation • and unusual hypopigmentation of the uveal tissues.
The equine fundus. III: Pathological variants. A wide range of ophthalmoscopic variants are encountered during routine examination of the horse. Some result from minor anatomical anomalies, cause no significant effect on vision and may be considered to lie within the limits of 'biological normality'. Others are a consequence of pathological disruption of the anatomical integrity of the fundus, and may directly or indirectly affect the neurosensory retina and produce some degree of visual deficit. This paper illustrates the ophthalmoscopic appearance of a number of pathological variants of the anatomic fundus, and discusses their possible e...
