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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.
Electroretinogram evaluation of equine eyes with extensive ‘bullet-hole’ fundic lesions. To evaluate the impact of extensive bullet-hole nontapetal fundic lesions in horses on retinal function as measured by full-field electroretinography (ERG). Methods: Full-field ERG was performed on two horses with numerous bullet-hole lesions in the nontapetal fundus of both eyes. The ERG was first recorded from the eye with the more extensive lesions in response to a low-intensity light stimulus (0.03 cd s/m(2) ) that was given at times (T) T = 5, 10, 15, 20 min of dark adaptation. Consecutively, combined rod-cone response was evaluated bilaterally in response to high-intensity light stimulus...
Comparison of tear pH in dogs, horses, and cattle. To determine baseline tear pH in dogs, horses, and cattle by use of a microelectrode. Methods: 28 dogs, 24 horses, and 29 cattle. Methods: Under manual restraint, tears were collected from each subject's left eye with cotton spears. A Schirmer tear test was performed in the right eye. Tears were extracted from the spears by centrifugation. Tear volume was measured, pH was determined with a microelectrode, and total solids (TS) concentration was measured by refractometry. Results: Mean ± SD pH of tears in cattle, dogs, and horses was 8.32 ± 0.14, 8.05 ± 0.26, and 7.84 ± 0.30, respectively. ...
The location of sites and effect of semiconductor diode trans-scleral cyclophotocoagulation on the buphthalmic equine globe. To determine appropriate location and energy settings for trans-scleral cyclophotocoagulation (TSCPC) for buphthalmic equine globes. Methods: Eleven horses with a buphthalmic eye blinded by glaucoma presented for enucleation. Methods: Globe and corneal dimensions were measured via ultrasonography and calipers, and TSCPC was performed under general anesthesia immediately prior to enucleation. Part 1: In nine globes, sixty sites were lasered 4 mm posterior to the limbus in the dorsotemporal and ventrotemporal quadrants at settings of 1500 milliwatts and 1500 ms. Globes were processed and section...
A retinoscopic survey of 333 horses and ponies in the UK. Ophthalmic examination in the horse is generally limited to crude assessment of vision and screening for ocular lesions. The refractive state of equine eyes and the potential impact on vision and performance requires further investigation. Objective: To assess the refractive state of a large, mixed-breed sample of horses and ponies in the United Kingdom (UK). Methods: The refractive state of both eyes of 333 horses and ponies was determined by streak retinoscopy, and the effect of age, height, gender, breed and management regime on the refractive state assessed. Results: Emmetropia was found i...
Stability of 1% voriconazole solution in a constant-rate infusion pump for topical ocular delivery to horses. To establish the effect of storage in a constant-rate infusion (CRI) pump on the sterility and stability of voriconazole 1% solution. Methods: Nine vials of voriconazole (Vfend(®) I.V.) 1% solution were prepared. Approximately half of each solution was used to prime a commercially available CRI pump with attached subpalpebral lavage system (CRI/SPL unit) with the remaining solution stored in the commercial glass vial. Three CRI/SPL units and their three corresponding vials were stored at one of three temperatures: 23 °C, 33 °C, and 40 °C. The CRI pumps ran for 7 days, and the vials were st...
Corneal dystrophy in Friesian horses may represent a variant of pellucid marginal degeneration. To describe the clinical presentation, treatment, and outcome of a corneal dystrophy in Friesian horses and to analyze affected horses' pedigrees to investigate its heritability. Methods: Nine Friesians with bilateral disease were identified. Methods: Retrospective medical record review was used to identify Friesian horses exhibiting bilateral symmetric corneal lesions. Variables identified from medical records included patient sex and age at diagnosis; location, depth and size of corneal lesions; medical and surgical therapy instituted; and visual outcome. A four-generation pedigree for each ...
Standing ophthalmic surgeries in horses. Standing ophthalmic surgery without general anesthesia allows for several routine ophthalmic procedures including eyelid lacerations and enucleations to be performed in the horse, but does contain increased risk of causing tissue damage arising from the inability to eliminate eye and head movements. Heavy sedation and local nerve blocks of the involved motor and sensory nerves are essential in achieving a good outcome from ophthalmic surgery in the nonanesthetized horse. The inability to use an operating microscope in standing surgery in horses prevents performing precise corneal and intraocul...
Clinical ophthalmic challenges in the horse: a retrospective view forward. The author reviews some aspects of vision and ophthalmic disease in the horse and considers how some recent developments in ocular immunobiology and molecular pathology in other species may give pointers toward an understanding of disease processes in the horse.
Treatment of nonhealing corneal ulcers in 60 horses with diamond burr debridement (2010-2013). To review the signalment, clinical characteristics, and outcome of horses with nonhealing corneal ulcers treated with diamond burr debridement (DBD); and to evaluate the role of ulcer duration, size and location, and bandage contact lens (BCL) placement on healing. Methods: From January 2012-April 2013, 60 horses were diagnosed with ulcers classified as nonhealing based on the presence of raised epithelial margins and duration of at least 7 days. Methods: Retrospective record review. Results: Average age of included horses was 14.68 years, SD 8.17 years. There were three times as many males (4...
Comparative evaluation of aqueous humor viscosity. To evaluate aqueous humor viscosity in the raptor, dog, cat, and horse, with a primary focus on the barred owl (Strix varia). Methods: Twenty-six raptors, ten dogs, three cats, and one horse. Methods: Animals were euthanized for reasons unrelated to this study. Immediately, after horizontal and vertical corneal dimensions were measured, and anterior chamber paracentesis was performed to quantify anterior chamber volume and obtain aqueous humor samples for viscosity analysis. Dynamic aqueous humor viscosity was measured using a dynamic shear rheometer (AR 1000 TA Instruments, New Castle, DE, US...
Ocular fungal flora from healthy horses in Iran. This study was carried out in order to isolate and identify the normal conjunctival fungal flora from Caspian miniature, Thoroughbred, Turkmen and Persian Arab breeds in Tehran, Iran. Methods: A total of seventy-two adult healthy horses were studied. Ocular samples were collected from right and left eyes by using sterile cotton swabs; samples were cultured on Sabouraud dextrose agar and incubated at 30°C for 7-10 days. Molds and yeasts were identified using macro and micro-morphological and physiological characteristics. Conclusions: Number of fungal colonies per eye varied between 0 and 123 ...
Treatment of six cases of equine corneal stromal abscessation with intracorneal injection of 5% voriconazole solution. To describe a reproducible technique for intrastromal injection in the standing horse for treatment of corneal stromal abscessation. Methods: A retrospective clinical study addressing the history, treatment, and outcome of six equids (six eyes) that received intrastromal voriconazole injection. Methods: Equids having a deep stromal abscess suspected to be of fungal origin were administered intrastromal injection of 5% voriconazole solution under standing sedation in an effort to bring about enhanced resolution of clinical disease. Results: Intracorneal administration of 5% voriconazole solutio...
Manual corneal thickness measurements of healthy equine eyes using a portable spectral-domain optical coherence tomography device. Corneal thickness measurements of the equine globe using spectral-domain optical coherence tomography (SD-OCT) have not been reported. Objective: To determine corneal thickness measurements and the intra- and interoperator reliability of a portable SD-OCT device in equine eyes. Methods: Prospective observational study. Methods: Horses free of ocular disease were used for this study. Gentle manual restraint, in combination with detomidine hydrochloride and a head stand, were employed to ensure proper animal positioning. Corneal pachymetry measurements were obtained from both eyes of each animal...
Clinical course of ophthalmic findings and potential influence factors of herpesvirus infections: 18 month follow-up of a closed herd of lipizzaners. To date the influence of herpesviruses on the development of equine ocular diseases has not been clearly determined. Objective: The purpose of this study was to illustrate the course of equine ocular findings over a period of 18 months at 6 month intervals, in correlation with the results of herpesvirus detection. Methods: 266 Lipizzaners in 3 federal states of Austria underwent complete ophthalmologic examination 4 times. Blood samples, nasal- and conjunctival swabs were obtained at the same time and used for the detection of the equid gammaherpesviruses EHV-2 and EHV-5 using consensus herpes...
Treatment and long-term follow-up of distichiasis, with special reference to the Friesian horse: a case series. Distichiasis is very uncommon in horses and treatment options and outcome remain unknown. Objective: To describe treatment and long-term follow-up of distichiasis in the horse. Methods: Retrospective clinical study. Methods: Case records of horses admitted for diagnosis and treatment of uni- or bilateral distichiasis between 2003 and 2012 were reviewed. Long-term (>6 months after last treatment) follow-up was by telephone conversation with the owner or referring veterinarian. Data were analysed using a Chi-squared test. Results: Eighteen cases were identified, of which 17 were Friesians. Al...
Equine deep stromal abscesses (51 cases – 2004-2009)–Part 1: the clinical aspects with attention to the duration of the corneal disease, treatment history, clinical appearance, and microbiology results. To study the equine deep stromal abscesses (DSA) with focus on the duration of the corneal disease, medical treatment, season of presentation, clinical appearance, and the degree of corneal vascularization. Methods: Equine DSA diagnosed, biopsied, and surgically treated at the University of Florida Veterinary Medical Center (UFVMC) from 2004 to 2009 were identified. The medical record, clinical photographic images, and microbiology results for each case were evaluated. Frequency and prevalence calculation as well as qualitative data analysis was performed for clinical and microbiological data....
Equine multiple congenital ocular anomalies and silver coat colour result from the pleiotropic effects of mutant PMEL. Equine Multiple Congenital Ocular Anomalies (MCOA) syndrome is a heritable eye disorder mainly affecting silver colored horses. Clinically, the disease manifests in two distinct classes depending on the horse genotype. Horses homozygous for the mutant allele present with a wide range of ocular defects, such as iris stromal hypoplasia, abnormal pectinate ligaments, megaloglobus, iridociliary cysts and cataracts. The phenotype of heterozygous horses is less severe and predominantly includes iridociliary cysts, which occasionally extend into the temporal retina. In order to determine the genetic ...
Evaluation of the conjunctival fungal flora and its susceptibility to antifungal agents in healthy horses in Switzerland. To characterize the conjunctival fungal flora and to determine the susceptibility of 2 isolated molds to antifungal drugs in samples of 64 healthy horses from The National Stud in Switzerland. Methods: Conjunctival cytobrush samples were collected from both eyes of 64 ophthalmologically normal horses in August 2012 and subsequently cultured on Sabouraud's agar medium. Growing fungi were identified and counted. Etests or broth microdilution tests for Aspergillus fumigatus and Eurotium amstelodami were carried out to determine antifungal drug sensitivity. These species had previously been detect...
Treatment of immune-mediated keratitis in horses with episcleral silicone matrix cyclosporine delivery devices. To describe the use of episcleral silicone matrix cyclosporine (ESMC) drug delivery devices in horses with immune-mediated keratitis (IMMK) with evaluation of tolerability and efficacy in long-term control of inflammation. Methods: Retrospective study. ESMC implants (1.2 cm length, 30% wt/wt cyclosporine (CsA) in silicone; with approximately 2 μg/day steady-state release for at least 400 days) were used. Results: Nineteen horses (20 eyes) received two or more ESMC implants for superficial stromal (n = 9), midstromal (n = 3), or endothelial (n = 5) IMMK. Three additional horses received two or...
Mast cell tumor invading the cornea in a horse. A 3-year-old Marwari mare was presented for evaluation of an irregular, reddish mass protruding from behind the right third eyelid. The mass appeared to arise at the ventral limbal area, involved the perilimbal bulbar conjunctiva and widely extended into corneal tissue. No other ocular or systemic abnormalities were detected at the time of presentation. The mass was surgically removed by lamellar keratectomy, with defocused CO(2) laser used as adjunctive therapy to treat the surgical exposed area and its surroundings. Histopathologic evaluation showed sheets of densely packed, well-differentia...
Feasibility of aqueous shunts for reduction of intraocular pressure in horses. Based on the current literature, neither medical, surgical nor combination therapy adequately controls equine glaucoma for many horses. Aqueous shunts have been useful in other species to control glaucoma. Objective: To determine whether aqueous shunts in normal equine eyes significantly reduce intraocular pressure (IOP) without causing vision threatening complications. Methods: Prospective experimental trial. Methods: Aqueous shunts were placed in 7 normal eyes of 4 horses. The shunts were placed dorsotemporally. Examinations were initially performed daily for 7 days and after that every 3 da...
Comparison of ultrasonography and histologic examination for identification of ocular diseases of animals: 113 cases (2000-2010). To compare ultrasonographic and histologic examination findings for eyes of animals with ocular diseases. Methods: Retrospective case series. Methods: 116 eyes of 113 animals examined at 2 facilities. Methods: Diseased eyes of animals were examined by means of ultrasonography, removed via enucleation or exenteration, then histologically examined. Ultrasonographic images and histopathologic slides were evaluated, and diseases of eyes were identified with each of those methods and allocated to various categories. For each disease category, agreement between results of ultrasonography and those o...
Prevalence of linear keratopathy in a herd of Lipizzaners over an 18-month period. The prevalence of linear keratopathy with progressing age in a closed population of a single horse breed is reported. All Lipizzaners in three federal states in Austria underwent complete ophthalmic examination four times over a period of 18 months, with six-month intervals. Findings consistent with linear keratopathy were recorded, and associated with factors such as sex, location, boarding system and level of performance throughout the study period. Logistic regression was applied to determine the influence of age on ophthalmic findings. On the first, second, third and fourth examinations, 0...
Evaluation of the effects of age and pituitary pars intermedia dysfunction on corneal sensitivity in horses. To determine effects of age and pituitary pars intermedia dysfunction (PPID) on corneal sensitivity in horses. Methods: 20 adult horses allocated into 3 groups (PPID group, old [> 15 years old] horses with PPID [n = 5]; old group, old [> 15 years old] horses without PPID [9]; and young group, young [≤ 10 years old] horses without PPID [6]). All horses with PPID had hirsutism and abnormal fat deposition or laminitis; none of the old or young horses had hirsutism, abnormal fat deposition, or laminitis. Methods: A Cochet-Bonnet aesthesiometer was used to measure the corneal touch threshol...
Eosinophilic keratitis in 46 eyes of 27 horses in the Mid-Atlantic United States (2008-2012). To review the signalment, clinical characteristics, treatment, and outcome of equine EK cases in the Mid-Atlantic United States; to evaluate the effects of topical or systemic corticosteroid treatment, oral cetirizine treatment and secondary corneal infection on disease duration; and to evaluate the association between corticosteroid and cetirizine treatment and likelihood of recurrence. Methods: Twenty-seven horses (47 eyes) diagnosed with EK from 2008 to 2012. Methods: Retrospective medical record review followed by phone interview to obtain recurrence data. Results: Average age of affected ...
