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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.
Glaucoma with Descemet’s membrane detachment in five horses. To describe the clinical and histopathologic features of glaucoma associated with Descemet's membrane (DM) detachment in five horses without prior history of intraocular surgery. Methods: Three Appaloosa horses and two Thoroughbreds were included in this study. The affected horses ranged in age from 16 to 27 years and presented with severe diffuse corneal edema. Methods: Five eyes were enucleated due to intraocular hypertension and/or chronic corneal ulceration. The enucleated globes were evaluated by the Comparative Ocular Pathology Laboratory of Wisconsin (COPLOW). Each globe was routinely ...
Field use of N-butylscopolammonium bromide to facilitate thorough ophthalmic examination in horses. N-butylscopolammonium bromide (NBB), an anticholinergic muscarinic antagonist, was assessed as a mydriatic agent for field examination of equine eyes. Six adult horses were randomly assigned to four treatments with 2 weeks washout between treatments: (1) topical saline/IV saline (negative control); (2) topical tropicamide/IV saline (positive control); (3) topical NBB/IV saline; or (4) topical saline/IV NBB. Horizontal and vertical pupil diameters, temperature, pulse, respiration, pupillary light reflexes (PLRs) and mydriasis sufficient to perform complete fundic examination were recorded. Trop...
Episcleral cyclosporine A implants for the management of unilateral keratoconjunctivitis sicca in an 8-year-old mare. An 8-year-old mare was presented for investigation of a 1-month history of blepharospasm, eyelid swelling, corneal edema, and ocular discharge of the right eye (OD). Ophthalmic examination confirmed mucopurulent ocular discharge, conjunctival hyperemia, and a dry, dull appearance to the cornea OD. Schirmer tear test results confirmed an absence of tear production OD (0 mm/min) consistent with keratoconjunctivitis sicca. Treatment with topical 0.2% cyclosporine A resulted in an improvement in clinical signs. An episcleral cyclosporine A implant was placed under standing sedation 5 days after in...
Modified penetrating keratoplasty with Acell® bioscaffold implant in seven horses with deep full-thickness corneal stromal abscess. To describe and evaluate a modified penetrating keratoplasty technique utilizing ACell® for management of equine deep stromal or full-thickness corneal stromal abscesses (SA). Methods: Cases presenting to the University of Georgia Ophthalmology service for surgical management of SA necessitating penetrating keratoplasty (PK) were included in the study population. Surgery entailed the use of an ACell® disk sutured within the deep level of a stepped full-thickness corneal incision with an overlying conjunctival pedicle flap placed in the superficial step incision. Patients were evaluated for s...
Corneal edema in four horses treated with a superficial keratectomy and Gundersen inlay flap. To describe the clinical presentation, treatment, and outcome of four horses with severe corneal edema caused by suspected endothelial disease treated with a superficial keratectomy and Gundersen inlay flap and to determine whether this procedure (i) reduces corneal edema, (ii) reduces ocular pain, (iii) eliminates recurrent corneal ulceration, and (iv) improves vision in these horses. Methods: Four horses met inclusion criterion of (i) diagnosis with endothelial disease by a board-certified veterinary ophthalmologist and (ii) surgical treatment with a superficial keratectomy and Gundersen inl...
Comparison of corneal degeneration and calcific band keratopathy from 2000 to 2013 in 69 horses. To compare signalment, presentation, treatment, and outcome in horses diagnosed with corneal degeneration (CD) or calcific band keratopathy (CBK) at a referral hospital. Methods: Sixty-nine horses (87 eyes) diagnosed with either CD or CBK. Methods: Medical records of horses diagnosed with CD or CBK at the University of California-Davis Veterinary Medical Teaching Hospital (UCD-VMTH) between 2000 and 2013 were reviewed. Signalment, concurrent ophthalmic diagnoses, previous therapies, diagnostic tests, systemic diagnoses, treatment, follow-up, and outcomes were compared between horses diagnosed ...
Multiple etiologies of equine recurrent uveitis–A natural model for human autoimmune uveitis: A brief review. Equine recurrent uveitis (ERU) has various etiologies, with Leptospira infection and genetic predisposition being the leading risk factors. Regardless of etiology, expression of ocular proteins associated with maintenance of the blood-ocular barrier is impaired in ERU. The recurring-remitting cycle of ERU repeatedly disrupts the blood-ocular barrier, allowing the previously immune-privileged ocular environment to become the site of a progressive local autoimmune pathology that ultimately results in tissue destruction and vision loss. The immune-mediated process involves humoral and cellular me...
Tear film osmolality and electrolyte composition in healthy horses. To evaluate the tear film osmolality and electrolyte composition in healthy horses. Methods: 15 healthy adult horses. Methods: Each horse was manually restrained, and an ophthalmic examination, which included slit-lamp biomicroscopy, indirect ophthalmoscopy, and a Schirmer tear test, was performed. Tear samples were collected from both eyes with microcapillary tubes 3 times at 5-minute intervals. The tear samples for each horse were pooled, and the osmolality and electrolyte concentrations were measured. The mean (SD) was calculated for each variable to establish preliminary guidelines for tea...
Distribution of CD163-positive cell and MHC class II-positive cell in the normal equine uveal tract. Antigen-presenting cells (APCs) in the uveal tract participate in ocular immunity including immune homeostasis and the pathogenesis of uveitis. In horses, although uveitis is the most common ocular disorder, little is known about ocular immunity, such as the distribution of APCs. In this study, we investigated the distribution of CD163-positive and MHC II-positive cells in the normal equine uveal tract using an immunofluorescence technique. Eleven eyes from 10 Thoroughbred horses aged 1 to 24 years old were used. Indirect immunofluorescence was performed using the primary antibodies CD163, MHC...
Equine eosinophilic keratitis in horses: 28 cases (2003-2013). This retrospective case series evaluates husbandry and environmental conditions in relation to eosinophilic keratitis in horses. While no associations were found between disease and husbandry practices or specific environmental factors such as humidity or temperature, an increased prevalence of presentation in summer months was identified in this population of horses.
Methicillin-resistant Staphylococcus aureus ulcerative keratitis in a Thoroughbred racehorse. We report the first case of methicillin-resistant Staphylococcus aureus (MRSA) keratitis in a racehorse. A 5-year-old mare developed punctate keratitis after racing. The corneal ulcer continued to expand despite ophthalmic antimicrobial therapy. On day 6, a conjunctival graft surgery was performed. The mare was euthanized, following colitis and laminitis development on day 10. MRSA was isolated from the corneal swab taken at the time of euthanasia. Immunohistochemical analysis demonstrated gram-positive and anti-S. aureus monoclonal antibody-positive cocci infiltration of the corneal stroma; a...
Ocular Pathology. Although not comprehensive of all ocular conditions in the equine species, this article concentrates on various ophthalmic conditions observed in the horse where laboratory diagnostics are recommended. The importance of laboratory diagnostic testing cannot be underestimated with equine ophthalmic disease. In many cases, laboratory diagnostics can aid in obtaining an early diagnosis and determining appropriate therapy, which in turn, can provide a better prognosis. In unfortunate cases where ocular disease results in a blind, painful eye necessitating enucleation, light microscopic evaluation i...
Prognosis and impact of equine recurrent uveitis. Equine recurrent uveitis (ERU) is a leading cause of vision loss in horses. Objective: To assess the prognosis and impact of ERU on affected horses and their owners by evaluating the signalment, treatment and outcome (including the loss of use, vision assessment and economic loss). Methods: Retrospective impact study. Methods: Medical records of horses presenting to the North Carolina State University Veterinary Health Complex (NCSU-VHC) with ERU between 1999 and 2014 were reviewed. Signalment, clinical signs, ophthalmic examination findings, treatments and outcomes were evaluated. Owner quest...
Introduction of the use of thermography and thermometry in the diagnosis of uveitis in horses: a pilot project. To date assessment of changes in ocular temperature, as a hallmark of uveitis in horses has not been determined. Therefore the aim of the current study was to determine whether ocular temperature is increased in acute uveitic eyes compared with non-uveitic eyes, and to compare an affordable thermometry device with a thermography device. Methods: Ocular temperatures of both eyes of five horses with acute unilateral uveitis and 10 normal horses were measured using thermometry and thermography. Presence and absence of acute uveitis were diagnosed through a complete ophthalmological examination. A...
Melanocytic Ophthalmic Neoplasms of the Domestic Veterinary Species: A Review. Melanocytic neoplasms in veterinary species occur in various ophthalmic locations including the eyelid, conjunctiva, cornea, sclera, anterior and posterior uvea, and orbit. Histology usually provides the definitive diagnosis for melanocytic ocular neoplasias. The degree of tissue invasiveness and anaplastic cellular characteristics are more reliable indicators of biological behavior than is mitotic index in most ophthalmic melanocytic tumors. Melanocytic neoplasias of the eyelid are predominantly benign in canines and equines, though in felines, there is the potential for metastasis, especiall...
Tear ferning test in horses and its correlation with ocular surface evaluation. To describe the tear ferning test (TFT) in healthy horses and its correlation with other parameters for evaluating the ocular surface. Methods: Thirty male and female adult healthy horses (60 eyes), of no defined breed. Methods: Tear sample was collected with a microcapillary tube, placed on the surface of a glass slide, and allowed to dry at room temperature. The crystallization pattern was classified according to Rolando (Chibret International Journal Ophthamology, 1984; 2, 32). The program STEPanizer(©) stereology tool, version 1.0, was utilized for counting points on the digitally capture...
Efficacy and safety of lomefloxacin on bacterial extraocular disease in the horse. Lomefloxacin is a broad-spectrum fluoroquinolone antibiotic used for the treatment of bacterial extraocular disease. This study investigated the efficacy and safety of lomefloxacin eye drops for bacterial extraocular disease in horses. Lomefloxacin ophthalmic solution (0.3%) was instilled three times daily for 2-5 days in 65 horses diagnosed with bacterial extraocular disease based on clinical findings. Clinical observations and bacteriological examinations were performed at the start of treatment, 2 and 5 days after the start of treatment, and at the discontinuation or termination of treatmen...
Detection of equine herpesvirus in horses with idiopathic keratoconjunctivitis and comparison of three sampling techniques. To determine the role of equine herpesvirus (EHV) in idiopathic keratoconjunctivitis in horses and to determine whether sample collection method affects detection of EHV DNA by quantitative polymerase chain reaction (qPCR). Methods: Twelve horses with idiopathic keratoconjunctivitis and six horses without signs of ophthalmic disease. Methods: Conjunctival swabs, corneal scrapings, and conjunctival biopsies were collected from 18 horses: 12 clinical cases with idiopathic keratoconjunctivitis and six euthanized controls. In horses with both eyes involved, the samples were taken from the eye judg...
Presumed primary ocular lymphangiosarcoma with metastasis in a miniature horse. A 7-year-old, 153.0-kg American Miniature mare presented for evaluation of keratoconjunctivitis of the right eye (OD). A superior palpebral conjunctival mass and stromal keratitis were diagnosed. The incisional biopsy diagnosis was a presumptive corneal hemangiosarcoma. Transpalpebral enucleation was performed, and histopathologic evaluation confirmed angiosarcoma of the conjunctiva, cornea, and extraocular muscles. The horse developed progressive epistaxis and orbital swelling following surgery. A systemic workup was performed 3 months after enucleation, revealing regrowth within the orbit an...
Unilateral choristoma of the nictitating membrane in a horse. A 2-year-old Morgan mare was evaluated because of a corneal ulceration. Results: An irregular, deep stromal corneal ulcer in an area of malacia was noted in the left eye. Hypopyon was present in the ventral portion of the anterior chamber with moderate aqueous flare. The nictitating membrane of the left eye had hairs originating from its leading edge that contacted the corneal surface. Results: General anesthesia was induced, and a bulbar pedicle conjunctival graft was performed. The conjunctiva at the leading edge of the nictitating membrane, including the aberrant hair follicles, was excised...
Effect of topical ophthalmic dorzolamide(2%)-timolol(0.5%) solution and ointment on intraocular pressure in normal horses. To compare the effect of commercially available solution and compounded ointment formulations of dorzolamide(2%)-timolol(0.5%) on intraocular pressure (IOP) of normal horses. Methods: Eighteen clinically normal horses. Methods: A randomized, masked prospective design was used with horses divided into two equal groups. One eye of each horse was selected for topical ophthalmic treatment with either 0.2 mL of dorzolamide(2%)-timolol(0.5%) solution or 0.2 g of dorzolamide(2%)-timolol(0.5%) ointment every 12 h for 5 days. The contralateral eye of horses in both groups was untreated. Rebound tonomet...
Porcine urinary bladder extracellular matrix grafts (ACell Vet® Corneal Discs) for keratomalacia in 17 equids (2012-2013). To describe the clinical course, outcomes, and complications associated with use of commercially available porcine urinary bladder extracellular matrix (ECM) grafts (ACell Vet(®) Corneal Discs) in equid patients with keratomalacia, and to evaluate the efficacy of ECM grafts as a viable alternative to other biomaterials for corneal grafting in equid patients. Methods: Sixteen horses and one donkey (17 eyes) with unilateral keratomalacia severe enough to warrant surgical repair between August 2012 and September 2013. Methods: Retrospective medical record review to identify equid patients meetin...
Clinical, histopathological and immunohistochemical characterization of a novel equine ocular disorder: heterochromic iridocyclitis with secondary keratitis in adult horses. To describe the clinical, histopathologic and immunohistochemical characteristics of an equine ocular inflammatory disease resulting in anterior uveitis and corneal endothelial inflammation associated with iris pigment dispersion and retrocorneal fibrous membrane (RFM) formation. Methods: Retrospective study. Methods: Sixteen horses with evidence of pigmented keratic precipitates (KPs), corneal edema, and/or iris depigmentation. Information collected from the medical records included signalment, clinical signs, prereferral treatment duration and response to therapy, ophthalmic examination find...
Ocular dimensions, corneal thickness, and corneal curvature in quarter horses with hereditary equine regional dermal asthenia. The aim of this study was to compare ocular dimensions, corneal curvature, and corneal thickness between horses affected with hereditary equine regional dermal asthenia (HERDA) and unaffected horses. Methods: Five HERDA-affected quarter horses and five healthy control quarter horses were used. Methods: Schirmer's tear test, tonometry, and corneal diameter measurements were performed in both eyes of all horses prior to ophthalmologic examinations. Ultrasonic pachymetry was performed to measure the central, temporal, nasal, dorsal, and ventral corneal thicknesses in all horses. B-mode ultrasound...
Evaluation of ultrasound velocity in enucleated equine aqueous humor, lens and vitreous body. Sonographic ophthalmic examinations have become increasingly important in veterinary medicine. If the velocity of ultrasound in ocular tissues is known, the A-mode ultrasound method may be used to determine the axial intraocular distances, such as anterior chamber depth, lens thickness, axial length of the vitreous and axial globe length, which are required for intraocular lens (IOL) power calculations. To the authors' knowledge, the velocity of ultrasound in the ocular tissues of the horse was not previously determined. In the present study, 33 lenses, 29 samples of aqueous and 31 of vitreous...
Limbal squamous cell carcinoma in Haflinger horses. To describe the prevalence of LSCC in Haflinger horses and to analyze affected horses' pedigrees investigating the genetic mode of inheritance. Methods: Fifteen horses met inclusion criterion of (i) being of the Haflinger breed, as confirmed by North American Haflinger Registry pedigree and (ii) being diagnosed with LSCC, as confirmed by clinical examination by a veterinary ophthalmologist or by histopathology. Pedigrees could not be obtained for four additional horses diagnosed with LSCC that had been identified as Haflingers. Methods: Retrospective medical record review of all 19 horses was ...
Assessment of intraocular measurements in neonatal foals and association with gender, laterality, and body weight: a clinical study. Objective of this study was to describe intraocular measurements in newly born foals (1-7 days of age) and assess the association between globe measurements and gender, laterality, and body weight. B-scan ultrasonographic biometry was performed on both eyes of 22 healthy foals (44 eyes) ages 1-7 days using a 10-MHz transducer. Intraocular measurements (anterior chamber depth, central lens thickness, vitreous chamber depth, axial globe length, longitudinal globe length, lens poles distance) were carried out using the ultrasound internal calipers. The influence of gender (male or female), latera...
Characterization and outcome following excision of masses in the nictitating membranes of horses: 50 cases (1998-2012). To determine the histologic findings associated with masses in the nictitating membranes (third eyelids) of horses and to identify prognostic factors associated with recurrence and the outcome. Methods: Retrospective case series. Methods: 50 horses with masses in a third eyelid. Methods: Medical records of horses with partial or complete excision of a third eyelid and submission for histologic evaluation between September 1998 and November 2012 were reviewed. Horses were included if follow-up information for at least 1 year after surgery was available. Information regarding signalment and trea...
Descemet’s membrane detachment in horses; case series and literature review. The aim of this article was to describe Descemet's membrane detachment (DMD) following phacoemulsification in five equine eyes and to review the human literature on this topic. In the last decade, there has been increased reporting of DMD in the human literature, in particular following cataract surgery. The natural history of DMD remains unknown and although various medical and surgical treatments have been advocated there is no recognized 'gold standard' treatment for DMD. This case series reports the diagnosis of DMD in four horses (5 eyes) in association with phacoemulsification surgery. T...
