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.
Saunders LZ, Bistner SI, Rubin LF.An asymptomatic, ophthalmoscopically visible proliferation affected the optic disc and nerve of two aged horses. The lesion consisted of an accumulation of foamy cells, histologically akin to fat cells, which contained an unidentified lipid-like material. The affected area and its environs were permeated by tortuous, thickened blood vessels with heavy deposits of collagen in their walls. The neuropathy is considered to be a storage disease, and although the product stored is unidentified, the lesion is similar to that of human xanthelasma. The neuropathy seems distinct from the exudative optic...
Garner A, Griffiths P.The purpose of this paper is to describe congenital defects, having no direct counterpart in
the literature, that affected both eyes of a new-born foal of pedigree racing stock, which
otherwise appeared to be entirely healthy as were both the sire and the dam.
ROBERTS SR.The research article explores the origin or causation (etiology) of an ancient horse disease known as equine periodic ophthalmia, where clinical and pathological investigations have yet to yield conclusive results. […]
Imposimato I, Mariella J, Freccero F, Gialletti R.Riboflavin/UV-A corneal cross-linking (CXL) has been applied to treat corneal ulcers in adult horses, but its use in critically ill neonatal foals has not been described. Five cases of hospitalized, critically ill neonatal foals that were in intensive care with corneal ulcers, the ophthalmic treatment, and their outcome up to 1 year are described. A single treatment of CXL phototherapy was performed in three of five foals (five eyes). The application of a riboflavin ophthalmic solution for 20 minutes was followed by the UV-A light irradiation at 30 mW/cm2 for 3 minutes. Topical antibiotic admi...
Sandmeyer LS, Bellone RR, Archer S, Bauer BS, Nelson J, Forsyth G, Grahn BH. To determine if congenital stationary night blindness (CSNB) exists in the Miniature Horse in association with leopard complex spotting patterns (LP), and to investigate if CSNB in the Miniature Horse is associated with three single nucleotide polymorphisms (SNPs) in the region of TRPM1 that are highly associated with CSNB and LP in Appaloosas. Methods: Three groups of Miniature Horses were studied based on coat patterns suggestive of LP/LP (n=3), LP/lp (n=4), and lp/lp genotype (n=4). Methods: Horses were categorized based on phenotype as well as pedigree analysis as LP/LP, LP/lp,...
Wilkie DA.Understanding and awareness of equine glaucoma has significantly improved in recent years. The availability of portable tonometers and veterinarian/owner awareness has increased the frequency of glaucoma as a clinical diagnosis. A variety of medications for the medical management of equine glaucoma have been evaluated and the addition of lasers has improved the surgical treatment of equine glaucoma. Despite this, equine glaucoma is an insidious and painful disease that probably remains under diagnosed and often results in blindness in the affected eye.
Scharre A, Scholler D, Gesell-May S, Müller T, Zablotski Y, Ertel W, May A.The aim was to compare ophthalmic diagnoses made by veterinarians to a deep learning (artificial intelligence) software tool which was developed to aid in the diagnosis of equine ophthalmic diseases. As equine ophthalmology is a very specialised field in equine medicine, the tool may be able to help in diagnosing equine ophthalmic emergencies such as uveitis. Methods: In silico tool development and assessment of diagnostic performance. Methods: A deep learning tool which was developed and trained for classification of equine ophthalmic diseases was tested with 40 photographs displaying various...
Blohm KO, Nell B.A 17-year-old Appaloosa mare was referred for evaluation of presumed refractory keratitis of the left eye. Gross examination revealed ocular discomfort and corneal neovascularization with a nasal focal opacification affecting approximately 40% of the corneal surface. On ophthalmic examination, extensive subepithelial to mid-stromal vascular branching accompanied by a homogeneous white, dense opacification, which affected up to 80% of the total corneal thickness, were apparent. Signs of concurrent uveitis were absent. Deep-stromal lamellar keratectomy with a conjunctival pedicle graft was perfo...
Tooley ZC, Eaton JS, Grant-Counard SM, Ilkenhans SM, Hetzel SJ, Bartholomew KJ.To compare the efficacy of low-volume (5-mL) locoregional retrobulbar anesthesia ("retrobulbar block") by use of 3 commercial local anesthetic formulations. Methods: 8 healthy adult mares. Methods: A block-randomized, masked, controlled design was used. A single ultrasound-guided retrobulbar block was performed with 2% lidocaine, 2% mepivacaine, or 0.5% bupivacaine (n = 5 eyes/group). Contralateral eyes served as untreated controls. End points performed at baseline and time intervals up to 24 hours postblock included the following: assessment of neurophthalmic reflexes/responses, intraocular p...
Pereira R, Gillespie S, Rapezzano G, Withers J, Duz M, Foote A.A 15-month-old, grey, Thoroughbred filly presented for investigation of a 6-week history of corneal oedema and blepharospasm on the right eye (OD). The filly was otherwise healthy. Following ophthalmic examination, glaucoma on the OD was diagnosed. A space occupying mass within the anterior chamber was documented on transpalpebral ultrasonographic examination. This mass obliterated most of the anterior intraocular structures on the peripheral nasal side (corneal endothelium and drainage angle), leading to secondary glaucoma. After systemic and topical treatment addressing secondary glaucoma, t...
Pereira R, Bowen M, Rapezzano G, Redpath A, Pratt S, Hallowell G.Recombinant intracameral tissue plasminogen activator (rTPA) administration can aid clearance of fibrin from the anterior chamber. In this retrospective multicentre case series, the effect of intracameral rTPA administration to treat fibrin in the anterior chamber resulting from trauma or inflammatory ocular disease was evaluated. Clinical data from 30 treatments in 29 horses were obtained from medical records from 2003 to 2022. Association between time from onset of clinical signs and time for rTPA treatment to effect was studied with regression analysis. Twenty-seven horses (93.1%) had no pr...
Collins EN, Barr EM, Westermeyer H, Gilger BC, Oh A.To determine the predictive value of corneal ultrasound biomicroscopy (UBM) findings for the outcome of equine corneal disease. Methods: 46 horses with a clinical diagnosis of either infectious ulcerative keratitis or stromal abscess. Methods: Corneal UBM (VevoMD; UHF70; VisualSonics) of horses with infectious corneal disease presenting to the North Carolina State University Equine Ophthalmology Service from 2019 to 2023 were evaluated. Size and depth of lesion, presence of Descemet membrane disruption (DMD), corneal thickness, and aqueous humor cell counts (AHCC) were assessed. Comparisons of...
Shnaiderman-Torban A, Pe'er O, Gustafsson K, Tatz A, Brizi M, Soback S, Abu Ahmad W, Magen R, Ofri R, Kelmer G.In equine glaucoma, topical treatment with carbonic anhydrase inhibitors (CAIs) is recommended. Oral acetazolamide, a systemic CAI, is used in horses with hyperkalemic periodic paralysis. Information regarding its effect on equine intraocular pressure (IOP) is scarce. The aim of the study was to determine the effect of oral acetazolamide treatment on IOP in horses, in a case-control study. Methods: Ten healthy horses. Methods: Horses were treated with oral acetazolamide (4.4 mg/kg) BID for 1 week. Serum acetazolamide concentrations were determined by liquid chromatography/tandem mass spect...
Roberts DM, Gilger BC.Equine fungal keratitis represents a substantial portion of keratitis cases in horses, with fungal involvement identified in approximately half of all infectious keratitis cases. Despite its prevalence, more comprehensive retrospective analyses are needed to better understand this condition. Outcomes vary, with approximately two-thirds of cases achieving complete healing with retained vision, although enucleation is often necessary. Predominant pathogens include Aspergillus and Fusarium, with yeast reported in a minority of cases. Resistance to common antifungal agents among filamentous fungi ...
Cho PW, Park SA, Sledge D, Gruenwald R, Townsend WM.The aim of this report was to provide a clinical description and clinical, ultrasonographic, and histologic images of a foal with microphthalmia and multiple ocular abnormalities. Methods: A 12-h old Friesian-American Paint Horse crossbred filly presented for blindness, microphthalmia and marked ventral strabismus in both eyes. Methods: A complete ophthalmic examination was performed. Ultrasound biomicroscopy and B-mode ultrasonography were performed. The globes were submitted for histopathology. Results: Ultrasound biomicroscopy demonstrated a hyperechoic cornea void of the typical epithelium...
Beldeanu S, Tay MCA, Daniel C, Dosi MCM, Hahn CN, James O, Townsend NB, Liuti T, Schwarz T, Parkinson NJ.Fractures of the paracondylar process of the occipital bone may cause headshaking, neck pain and neurologic deficits. The condition is being recognised more frequently with increasing availability of computed tomography. However, to date only limited information is available as to presentation, treatment, surgical approach and outcome. Objective: To describe the clinical signs, imaging findings, treatment, surgical approach and outcome in three horses diagnosed with paracondylar process fracture. Methods: Retrospective case series. Methods: Clinical records and diagnostic images of affected ca...
Mascaró Triedo CE, Karar S, Abunemeh M, Portier K.Pupillometry is used in humans to monitor pain, nociception and analgesia. This single-center, non-randomized, non-blinded intervention trial, evaluated the effect of nose twitching on the pupil size in awake, sedated, and anesthetized horses. Pupil height (H) and length (L) were measured before (Be) and after (Af) nose twitching in fourteen non-painful adult awake horses (T0). The percentage of variation (PSV) was calculated (PSVTn = [(TnAf-TnBe)/TnBe]*100). Measurements were repeated (Tn) after acepromazine (0.04 mg kg IV) (T1), romifidine (0.04 mg kg IV) (T2), morphine (0.1 mg...
Gould J, Wells M, de Linde Henriksen M, Gilger BC.To determine the causes, time to resolution, effect of therapeutics, and ocular sequelae of hyphema, fibrin, and/or vitreal hemorrhage in horses. Methods: 225 horses (219 eyes) who were diagnosed with hyphema, fibrin, and/or vitreal hemorrhage. Methods: Records were retrospectively reviewed for the horses. Signalment, ophthalmic examination findings, causes, treatments, and outcomes were evaluated. Results: Common causes of intraocular fibrin or hemorrhage were equine recurrent uveitis (42/219 horses), corneal stromal abscess (32/219 horses), corneal stromal ulcer (25/219 horses), and trauma (...
Conduit S, Bowen M, Hallowell G, Pereira R, Rapezzano G, Redpath A.Equine primary iris cysts are usually incidental findings but, if associated with clinical signs, may require intervention. The use of laser (Nd:Yag or diode) has been reported but requires specialised equipment. Transcorneal aspiration has not been previously evaluated in the standing horse. To review outcomes of standing transcorneal aspiration of primary iris cysts (STAPIC) in horses. Horses were identified from electronic patient records from 2018 to 2024 across four collaborating centres. Clinical presentation and outcomes were identified and reported using descriptive statistics. Eightee...
Charnock LN, McMullen RJ.To describe a combined treatment approach for heterochromic iridocyclitis and secondary keratitis (HIK) in horses. Methods: A total of 15 horses (16 eyes). Methods: Sixteen eyes from 15 horses (mean age 14.1 years, range 6-26 years) received low-dose (4 mg) intravitreal preservative-free gentamicin injection (IVGI) and modified Gundersen grafts with standing sedation and local anesthesia following a clinical diagnosis of HIK. Additional therapies of suprachoroidal triamcinolone (8 mg) injection, episcleral bromfenac implants, and suprachoroidal cyclosporine implants were performed in i...
Anandu S, Tanuj GN, Vijayasarathi MK, Manjusha KM, Samanta S, Bandyopadhyay S, Sankar M.Ocular setariasis is an ectopic infection caused by a parasite under the genus Setaria. Adult worms belong to the Setariidae family and typically reside in the peritoneal cavity of ungulates. However, immature forms of these species may aberrantly migrate to the eyes of cattle, buffalo, goats, horses and several other hosts, leading to corneal opacity and blindness. Here, we have distinguished the Setaria digitata collected from both equine and buffalo hosts based on the morphology, molecular profiling of mitochondrial cytochrome c oxidase subunit 1 (Cox1), cytochrome c oxidase subunit 3 (Cox3...
Preston JF, Mustikka MP, Priestnall SL, Dunkel B, Fischer MC.There is limited literature regarding equine immune mediated keratitis (IMMK) in Europe. North America-based publications describe minimal blepharospasm, rare corneal ulceration and no uveitis; clinical impression suggests these are seen in Europe. Objective: Assess the prevalence of blepharospasm, corneal ulceration and uveitis and their impact on outcome in horses diagnosed with IMMK in Europe (UK and Finland). Methods: Retrospective case series. Methods: Clinical records of 94 horses with IMMK were evaluated. The UK and Finland populations were comparable; therefore, descriptive statistics ...
Labelle AL, Gemensky Metzler AM, McMullen RJ, Wiggans KT, Labelle P, Hamor RE.To describe the clinical appearance, histopathology, and treatment of equine intraocular melanocytic neoplasia in adult horses. Unassigned: A retrospective review of medical records was conducted. Data recorded included signalment, ocular examination findings, physical examination findings, therapeutic interventions, and case outcomes. Histopathologic characteristics of enucleated globes were evaluated. A Student's -test was used to evaluate differences in the interval from diagnosis to last known outcome between horses receiving therapeutic interventions and horses undergoing monitoring alone...
Faghihi H, Gharibi A, Ansari Mood M, Rajaei SM, Alavi SM.The aim of this study was to detect and describe ocular abnormalities in a population of Turkmen horses. Methods: A total of 55 Turkmen horses (33 mares and 22 stallions) from one herd were evaluated in this study. Methods: Demographic data (Age, Sex, Coat color) were recorded. All animals underwent complete ophthalmic examination. The Schirmer tear test -I (STT-I) was performed for all horses prior to other diagnostic tests. Neuro-ophthalmic examinations (menace response, dazzle reflex, pupillary light reflex, maze test, and visual tracking) were carried out in different lighting situations (...
Smith HL, Love KR, Antezana A, Barr EM, Gilger BC, Oh A.To determine clinical outcome, treatment costs, and hospitalization duration in horses treated for keratomycosis and identify ophthalmic examination and diagnostic results associated with these outcomes. Methods: This was a retrospective study of 126 equine keratomycosis cases between 2004 and 2020 with fungal infection confirmed on cytology, culture, and/or histopathology and a minimum of 1-month follow-up. Details of the ophthalmic examination, diagnostic test results, and treatment and cost outcomes were recorded. Outcomes of interest were analyzed by treatment type. The relationship of pat...
Allen R, Goodhead AD.Warmblood horses are a popular breed around the world for equestrian sports. Previous studies have investigated ocular findings in other breeds of horses; however, no studies exist for the Warmblood breed. Objective: To determine the prevalence of ocular abnormalities in a convenience sample of Warmblood horses in South Africa and to determine if the prevalence of lens and chorioretinal lesions increase with age. Methods: Descriptive, observational study. Methods: Warmblood horses underwent a full ophthalmic examination which included a Schirmer tear test (STT), tonometry, fluorescein dye test...
Sano Y, Miura C, Kinoshita Y, Kakimoto M, Tsuda T, Matsuda K.Congenital cystic eye (CCE) is a rare congenital ocular disease, which has been suggested to be caused by problems with optic vesicle invagination. This is characterized by the formation of intraorbital cystic lesions lined by undifferentiated neuroepithelium. However, cases involving ocular structures with varying degrees of differentiation have also been reported as CCE in humans and animals. In horses, CCE have only been reported as a case presenting as neuroepithelial-lined cysts without the formation of ocular structures. This paper describes large bilateral intraorbital cysts in a 1-day-...
Morris JM, Lassaline ME, Nunnery CM, Teixeira LBC, Martins BC, Moore BA, Knickelbein KE, Scherrer NM, Plummer CE.Little information describing the biologic behaviour and therapies for corneal lymphoma exist. Objective: To characterise histologically confirmed equine corneal lymphoma considering breed, age or sex predisposition, histologic and immunologic features, therapies and outcomes. Methods: Retrospective case series. Methods: A multicentre retrospective medical record review was used to identify horses that presented with corneal disease confirmed morphologically as corneal lymphoma from 2012 to 2022. Results: Mean age at diagnosis was 10.5 years. Males represented 18/26 cases. Warmblood (14) and...
McMullen RJ.To review data on the advances in equine ophthalmic imaging that have been made during the past 5 years and highlight advantages of using multiple imaging modalities to improve clinical observational skills and improve diagnostic accuracy. Methods: A literature review from 2019 through 2024 of equine ophthalmic digital photography, fundus photography, ocular and orbital ultrasonography (US), ultrasound biomicroscopy (UBM), confocal microscopy (CM), spectral domain optical coherence tomography (SD-OCT), radiography, CT, and MRI. Results: Digital photography remains the cornerstone of equine oph...
Larsen MME, Eriksson A, Impellizeri JA.To describe the procedure and outcome of electrochemotherapy (ECT) with bleomycin as a first-line treatment for bilateral ocular surface squamous neoplasia (OSSN) in the eye of a horse. Methods: A client-owned 5-year-old Haflinger gelding with limbal-conjunctival squamous cell carcinoma. Methods: During general and local anesthesia, injection of bleomycin in the ocular tumor was followed by electroporation, applied with a 15 mm needle electrode, needles held parallel to the ocular surface. Results: Treatment with ECT resulted in therapeutic electric pulses and complete tumor response with no...
Farkas A, Thieme K, Soimala T, Jensen CK, Eule JC.This retrospective study evaluates the efficacy of povidone-iodine (PI) and polyhexamethylene biguanide (PHMB) as preoperative antiseptics in equine ophthalmic procedures. Methods: Horses that underwent routine ophthalmic surgery and procedures. Methods: Data were collected retrospectively from the medical records of equine patients undergoing ophthalmic procedures. Inclusion criteria were sampling for aerobic microbial culture at three different time points (T0: pre-irrigation, T1: post-irrigation, and T2: postoperatively) and T0 showing bacterial growth. Microbiological outcomes were assesse...
Stafford LS, Plummer CE, Smith WC, Gibson DJ, Sharma J, Vicuna V, Diakite S, Larkin J.Recurrent uveitis (RU), an autoimmune disease, is a leading cause of ocular detriment in humans and horses. Equine and human RU share many similarities including spontaneous disease and aberrant cytokine signaling. Reduced levels of SOCS1, a critical regulator of cytokine signaling, is associated with several autoimmune diseases. Topical administration of SOCS1-KIR, a peptide mimic of SOCS1, was previously correlated to reduced ocular pathologies within ERU patients. Unassigned: To further assess the translational potential of a SOCS1 mimetic to treat RU, we assessed peptide-mediated modulatio...
Gerras J, Young K, Roberts D, Waldman G, Salmon JH, Gilger BC.To describe the ocular findings, chronology of disease, and serum leptospiral titers in a group of horses, mules, and donkeys following an outbreak of leptospirosis. Unassigned: Fifty Equidae in central North Carolina had ophthalmic examinations and serum leptospiral microscopic agglutination test (MAT) titers performed every 3-6 months for 24 months followed by a final examination at 34 months. Unassigned: Throughout the nearly three-year study period, 17 horses (34%; 17/49 horses) developed signs of uveitis; 20 eyes (20/34; 58.8%) of these 17 horses were visual at the initial examinati...
