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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.
Exophthalmus secondary to a sinonasal cyst in a horse. A 13-year-old female Miniature Horse was evaluated for progressive unilateral exophthalmia of the left globe of 3 weeks' duration. Results: Results of a physical examination were unremarkable. Ophthalmic examination identified exophthalmus of the left globe with complete resistance to retropulsion and mild blepharoconjunctivitis. Computed tomography revealed a large, space-occupying mass within the left caudal maxillary and left conchofrontal sinuses. The mass extended into the left retrobulbar space and contacted the cribriform plate. Trephination yielded copious amounts of turbid yellow flui...
Diagnostic ophthalmology. Squamous cell carcinoma. The research article deals with a case study of an 18-year old male horse suffering from an enlarging mass on its right lower eyelid, which was examined and diagnosed at [...]
Surgical management of a progressive iris melanocytoma in a Mustang. A 7-year-old gray Mustang gelding weighing 454 kg was presented for evaluation of a brown mass within the left eye (OS) of 1 year's duration with recent enlargement. Results: A nonpainful, 8 mm diameter, brown, vascularized mass was identified in the anterior chamber of the OS. Ocular B-scan ultrasound confirmed iris involvement and corneal endothelial contact. Histopathology confirmed the presumptive diagnosis of a uveal melanocytic neoplasm, and revealed 1-3 mitotic figures per high power (400x) field. Results: The mass was removed via sector iridectomy without complications, but without com...
Corneal transplantation for inflammatory keratopathies in the horse: visual outcome in 206 cases (1993-2007). To evaluate the visual outcome of three techniques of corneal transplantation surgery in treating severe inflammatory keratopathies in the horse. Methods: Retrospective medical records study. Methods: Medical records of 206 horses that received corneal transplantation surgery at the University of Florida Veterinary Medical Center from 1993 to 2007 were reviewed. Methods: Data collected from the medical records included signalment, types of ocular lesions, type of transplant surgery performed, length of follow-up, complications, and visual outcomes. Results: Full thickness penetrating keratopla...
In vitro efficacy of an ophthalmic drug combination against corneal pathogens of horses. To evaluate the in vitro efficacy of an ophthalmic drug combination against common corneal pathogens of horses. Methods: Representative isolates of 3 bacterial and 2 fungal corneal pathogens of horses. Methods: Pathogens were subjected to minimum inhibitory concentration (MIC) testing of a drug combination that consisted of equal volumes of natamycin 3.33%, tobramycin 0.3%, cefazolin 5.5%, and equine serum. Proteinase inhibitory activity of the drug combination was assessed by use of a fluorescence microplate assay with gelatin and collagen I as substrates. The MICs of the drug combination wer...
Multidisciplinary management of a complicated orbital injury inflicted by a horse. This case report describes an unusual and complicated orbital injury inflicted by a horse. Definitive management required multidisciplinary surgical collaboration to prevent significant ocular sequelae. The diagnostic role of good imaging and the potential use of bio-models are highlighted.
Solute transport in the deep and calcified zones of articular cartilage. (1) To establish whether the tidemark and calcified cartilage are permeable to low molecular weight solutes, thereby providing a potential pathway for nutrition of cells in the deep cartilage. (2) To investigate transport from the subchondral microcirculation into calcified cartilage in an intact perfused joint and the effects on transport of static loading. Methods: The permeability of the tidemark and calcified cartilage was investigated in plugs of cartilage and subchondral bone which formed the membrane of a diffusion cell. Transport from the subchondral microcirculation and the effects of...
Detection of Leptospira interrogans DNA and antigen in fixed equine eyes affected with end-stage equine recurrent uveitis. Equine recurrent uveitis (ERU) is the most frequent cause of blindness in horses worldwide. Leptospira has been implicated as an etiologic agent in some cases of ERU and has been detected in fresh ocular tissues of affected horses. The objective of this study was to determine the presence of Leptospira antigen and DNA in fixed equine ocular tissues affected with end-stage ERU. Sections of eyes from 30 horses were obtained. Controls included 1) 10 normal equine eyes and 2) 10 equine eyes with a nonrecurrent form of uveitis. The experimental group consisted of 10 eyes diagnosed with ERU based on...
Pharmacokinetics of topically applied ciprofloxacin in equine tears. To evaluate the pharmacokinetics of topically applied ciprofloxacin 0.3% ophthalmic solution in tears of healthy horses. Methods: Twenty healthy, adult, mixed-breed horses. Methods: Twenty study horses were confirmed free of ophthalmic disease by complete ophthalmic examination. Seventy microliters of 0.3% ciprofloxacin (Ciloxan) was placed in the ventral cul-de-sac of each eye using a microliter syringe and 19-g cannula. Population kinetics were carried out by sampling the tear film from the lower cul-de-sac of each eye with tear test strips at 5, 10, 15 and 30 min and 1, 2, 4 and 6 h post ad...
Clinical and electroretinographic characteristics of congenital stationary night blindness in the Appaloosa and the association with the leopard complex. To determine the prevalence of congenital stationary night blindness (CSNB) in Appaloosa horses in western Canada, investigate the association with the leopard complex of white spotting patterns, and further characterize the clinical and electroretinographic aspects of CSNB in the Appaloosa. Methods: Three groups of 10 Appaloosas were studied based on coat patterns suggestive of LpLp, Lplp, and lplp genotype. Methods: Neurophthalmic examination, slit-lamp biomicroscopy, indirect ophthalmoscopy, measurement of corneal diameter, streak retinoscopy, scotopic and photopic full-field and flicker ER...
Retinal detachment in horses: 40 cases (1998-2005). To determine clinical features, ophthalmic examination findings, etiology, treatment, and outcome of horses diagnosed with retinal detachment (RD). Methods: Forty horses, presented to the North Carolina State University and The Ohio State University Veterinary Teaching Hospitals from 1998 to 2005 that were diagnosed with RD. PROCEDURE(S): Horses with documented RD, confirmed either on ophthalmic examination or by ultrasonography, and with a complete medical record were included. Information retrieved from the medical records included signalment, presenting complaint, duration of clinical signs...
Evaluation of the in vivo behaviour of gentamicin sulphate ocular mini-tablets in ponies. The in vivo behaviour of 5% gentamicin sulphate ocular mini-tablets (2-mm diameter, 6.525 mg weight) was compared with gentamicin eye drops in six ponies. Two mini-tablets were inserted on the bulbar conjunctiva of the right eye while a similar dose of gentamicin was administered via eye drops in the left eye. Irritation induced by the mini-tablets and the eye drops was evaluated using a visual analogue scale (0-10). Tears were sampled with ophthalmologic absorption triangles for 1 min for the determination of the concentration of gentamicin sulphate using a microbiological plate diffusion met...
Grid keratotomy as a treatment for superficial nonhealing corneal ulcers in 10 horses. To describe the clinical symptoms of 10 cases of superficial nonhealing corneal ulcers in horses and to evaluate the results of grid keratotomy in these patients. Methods: Retrospective study. Methods: Ten horses with superficial nonhealing corneal ulceration in one eye. Methods: The signalment, history and clinical symptoms are reported of 10 patients with superficial nonhealing corneal ulcers during the period from August 2003 to February 2005. Grid keratotomy was performed in all cases. In addition, the surgical procedure of grid keratotomy and response to therapy are described. Results: Ho...
Ophthalmic emergencies in horses. The emergency clinician is frequently in the position of receiving, evaluating, and initiating treatment on horses with ophthalmic emergencies or orbital trauma. In the best of circumstances, an ophthalmologist is available to guide initial therapy and ultimately assume responsibility for the management of the patient during the remainder of its hospitalization, but this is not always the case. The information presented here is meant to provide the emergency clinician with basic guidelines for the initial assessment and management of horses sustaining ocular injuries or presented with an ophth...
Comparison of cytologic and histologic evaluations of the conjunctiva in the normal equine eye. To describe the cells observed in conjunctival brush cytology (CBC) from normal horses and compare these findings with conjunctival structural histology so as to understand which cells are recovered from CBC. Methods: This study was divided into three parts. (1) Conjunctival brush smears were collected from 20 healthy horses on both eyes and a differential count on 300 cells was carried out on May Grünwald-Giemsa (MGG) smears. (2) A similar protocol was used for whole eyes from five horses obtained rapidly after death from a slaughterhouse. The eyes were then assessed for conjunctival histolo...
Combined keratectomy, strontium-90 irradiation and permanent bulbar conjunctival grafts for corneolimbal squamous cell carcinomas in horses (1990-2002): 38 horses. The purpose of this study was to evaluate the effectiveness of postoperative beta-irradiation with strontium-90 as an adjunctive treatment to superficial keratectomy and permanent bulbar conjunctival graft for removal of equine corneolimbal squamous cell carcinoma (SCC), in decreasing recurrence rate. Methods: The retrospective case study included 38 horses diagnosed and treated for SCC of the eye that involved the limbus and/or cornea. The patients were treated between 1990 and 2002, with strontium-90 irradiation immediately after corneal and conjunctival graft surgery. Recurrence was defined...
Occurrence of fungi from conjunctiva of healthy horses in Tuscany, Italy. The fungal flora of the normal conjunctival fornix has been described for many animal species (Urban et al., 1972; Samuelson et al., 1984; Moore et al., 1988; Davidson et al., 1994; Cooper et at, 2001) and many environmental factors, such as age, geography, habitat and husbandry are reported to influence its composition (Samuelson at at, 1984; Andrew et at, 2003). Equine keratomycosis can be caused by saprophytic fungi following an underlying corneal pathology or improper use of topical antibiotics and/or topical corticosteroids (Andrew at al., 1998; Brooks, 1999). Knowledge of differences in ...
Amniotic membrane transplantation for corneal surface reconstruction after excision of corneolimbal squamous cell carcinomas in nine horses. The purpose of this study was to evaluate the usefulness and effectiveness of permanent amniotic membrane transplantation as an adjunctive treatment to superficial keratectomy alone or combined with strontium-90 irradiation for treatment of equine corneolimbal squamous cell carcinoma (SCC) to decrease corneal scarring and recurrence rate. Methods: The retrospective case study included 11 horses (n = 12 eyes) diagnosed and treated for ocular SCC that involved the limbus and cornea. Nine of those horses (n = 9 eyes) were treated between 2002 and 2006, with superficial lamellar keratectomy alone ...
Keratometry, biometry and prediction of intraocular lens power in the equine eye. To determine ocular dimensions (A- and B-scan ultrasound) and corneal curvature (radius of corneal diameter determined in B-scan ultrasound) in the equine eye and to calculate the appropriate dioptric power for a posterior chamber intraocular lens (IOL) necessary to achieve emmetropia in the eyes of horses undergoing lens extraction. Methods: Fourteen clinically normal adult horses of various breeds. Additionally, for comparison, one American Miniature colt foal, and one 2.5-year-old Shire gelding were examined. Methods: B-scan ultrasound was performed on one eye from each horse. One eye from ...
Clinical features and outcomes of phacoemulsification in 39 horses: a retrospective study (1993-2003). To identify visual outcome and postoperative complications following phacoemulsification of equine cataracts. Methods: Records of 39 horses (55 eyes) with cataracts were reviewed. Methods: Eyes with cataracts removed by phacoemulsification were included in the study. Data collected included age, breed, sex, stage and etiology of cataract, unilateral vs. bilateral involvement, and ultrasound findings. Horses were grouped by etiology of the cataract. Visual outcome and complications were evaluated for each group and the overall population. Results: Immediately postoperatively 46 out of 47 eyes (...
Prevalence of equine herpesvirus type 2 (EHV-2) DNA in ocular swabs and its cell tropism in equine conjunctiva. Equine herpes virus 2 (EHV-2), a gamma(2)-herpesvirus, is common in horses of all ages. Its role as a primary pathogen is unclear but there is an association between EHV-2, respiratory disease and keratoconjunctivitis. The purpose of this study was to gain more information on the prevalence of EHV-2 DNA in conjunctival swabs from horses with and without ocular disease and to define the anatomical site and cell type harbouring viral genome or antigen. By polymerase chain reaction (PCR) 22 out of 77 (28.6%) ocular swabs of clinically healthy and only 4 out of 48 (8.3%) samples from diseased hors...
Infections of the head and ocular structures in the horse. Infectious conditions of the equine head are commonly encountered in clinical practice. Pathogenic bacterial, viral, and fungal organisms may localize in the extensive nasal passages, paranasal sinuses, and guttural pouches, creating a range of clinical signs and conditions that can be severe enough to lead to unexpected fatality. Renewed interest in equine dentistry has led to a greater recognition of dental disease that is associated with infection. This article focuses on bacterial and fungal infections of the main anatomic regions of the equine head, where advances in diagnosis and managem...
Effect of head position on intraocular pressure in horses. To evaluate the effect of head position on intraocular pressure (IOP) in horses. Methods: 30 horses. Methods: Horses were sedated with detomidine HCl (0.01 mg/kg, IV). Auriculopalpebral nerve blocks were applied bilaterally with 2% lidocaine HCl. The corneas of both eyes were anesthetized with ophthalmic 0.5% proparacaine solution. Intraocular pressures were measured with an applanation tonometer with the head positioned below and above heart level. The mean of 3 readings was taken for each eye at each position for data analysis. The effect of head position on IOP was assessed and generalized ...
In vitro efficacy of a buffered chelating solution as an antimicrobial potentiator for antifungal drugs against fungal pathogens obtained from horses with mycotic keratitis. To determine whether a novel third-generation chelating agent (8 mM disodium EDTA dehydrate and 20 mM 2-amino-2-hydroxymethyl-1, 3-propanediol) would act as an antimicrobial potentiator to enhance in vitro activity of antifungal medications against fungal isolates obtained from horses with mycotic keratitis. Methods: Fungal isolates (3 Aspergillus isolates, 5 Fusarium isolates, 1 Penicillium isolate, 1 Cladosporium isolate, and 1 Curvularia isolate) obtained from horses with mycotic keratitis and 2 quality-control strains obtained from the American Type Culture Collection (ATCC; Candida albica...
The use of mitomycin C as an adjunctive treatment for equine ocular squamous cell carcinoma. To assess the effectiveness of topical mitomycin C application as an alternative adjunctive therapy to CO2 laser ablation in the treatment of equine ocular squamous cell carcinoma. Methods: A retrospective clinical study of eight client owned horses in which 10 affected eyes were treated for ocular squamous cell carcinoma over a 17 month period. (March 2003 to August 2004). Methods: Each horse was given a general anaesthetic to allow CO2 laser ablation of the lesion(s). Mitomycin C at a concentration of 0.4 mg/mL was then applied intraoperatively to the affected areas for 1 or 5 minutes. Posto...
Ophthalmic examination findings of Thoroughbred racehorses in Australia. To record the prevalence and document the types of eye disease in population of Thoroughbred racehorses in Victoria, Australia. Methods: Prospective study. Methods: Two hundred four Thoroughbred racehorses. Methods: All horses and both eyes were examined at four metropolitan and two country racing stable complexes. Ophthalmic exam was performed following dark adaptation with a transilluminator, biomicroscope, and direct ophthalmoscope. Intraocular pressures were measured when indicated. Both pupils were dilated with tropicamide when indicated. Results: One hundred eighty-two (89.2%) flat-racin...
