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.
Best LJ, Alexiades V, Hendrix DVH, Chen T, Ward DA.OBJECTIVE To describe qualitative blinking patterns and determine quantitative kinematic variables of eyelid motion in ophthalmologically normal horses. ANIMALS 10 adult mares. PROCEDURES High-resolution videography was used to film blinking behavior. Videotapes were analyzed for mean blink rate, number of complete versus incomplete blinks, number of unilateral versus bilateral blinks, and subjective descriptions of blinking patterns. One complete blink for each horse was analyzed with image-analysis software to determine the area of corneal coverage as a function of time during the blink and ...
Hampson ECGM, Gibson JS, Barot M, Shapter FM, Greer RM.To identify bacteria and fungi found on the conjunctival surface of normal horse eyes; to investigate potential risk factors for these microflora; and to determine their susceptibility to common topical ophthalmic antimicrobials. Methods: A total of 95 client-owned horses were studied. Methods: Horses within sub-tropical Australia (South-East Queensland) were sampled once between April 2012 and March 2013. A conjunctival swab was taken from each eye and cultured for aerobic bacteria and fungi. Organisms were identified by colony morphology and phenotype. Antimicrobial disk diffusion susceptibi...
Pirie CG, LoPinto AJ, Tenney WA.OBJECTIVE To assess and compare 2 injection techniques for conducting ocular anterior segment indocyanine green angiography (ASICGA) and sodium fluorescein (SF) angiography in horses. ANIMALS 3 healthy adult female horses (age range, 19 to 25 years). PROCEDURES Horses were sedated, jugular catheters were placed, and manual restraint was used to ensure proper positioning for the angiography procedure. Two injection techniques (IV and intra-arterial) were performed for each horse 1 week apart. Intravenous injections of 0.25% indocyanine green (ICG; 50 mg) and 10% SF (10 mg/kg) were administered ...
Shank AMM, Teixeria LBC, Dubielzig RR.Corneal vascular neoplasms (hemangioma and hemangiosarcoma) are rare in all species. Reported cases are single case reports in a single species. Archived cases of corneal hemangioma and hemangiosarcoma from dogs, cats, and horses were obtained from the Comparative Ocular Pathology Lab of Wisconsin (COPLOW, Madison, WI), tabulated, and examined. This retrospective study describes the breeds, ages, tumor types, and characteristics of vascular neoplasms that appeared to be primarily corneal in location, in feline, canine, and equine patients, with gross and histologic images. There is a discussio...
Proietto L, Beatty SS, Plummer CE.To compare corneal cytology samples from three common sampling techniques: cytobrush (CB), Kimura platinum spatula (KS), and the handle edge of a scalpel blade (SB). Methods: Equine patients presenting to the University of Florida College of Veterinary Medicine with ulcerative keratitis were included. Following diagnosis of corneal ulcer and sampling for microbial culture, two cytology samples per technique were collected with sterile CB, KS, and SB in a randomized order. Cytologic evaluation was performed by two observers masked to collection method. Objective measures of sample cellularity, ...
Curto EM, Griffith EH, Posner LP, Walsh KT, Balko JA, Gilger BC.OBJECTIVE To compare complications between healthy horses undergoing general anesthesia for ophthalmic versus non-ophthalmic procedures and identify potential risk factors for the development of complications. DESIGN Retrospective case series. ANIMALS 502 horses (556 anesthetic procedures). PROCEDURES Medical records from January 2012 through December 2014 were reviewed to identify horses undergoing general anesthesia. Signalment, body weight, drugs administered, patient positioning, procedure type (ophthalmic, orthopedic, soft tissue, or diagnostic imaging), specific procedure, procedure time...
Meister U, Görig C, Murphy CJ, Haan H, Ohnesorge B, Boevé MH.Phacoemulsification and intraocular lens (IOL) implantation during cataract surgery in horses occur with increasing frequency. To reduce the postoperative refractive error it is necessary to determine the proper IOL power. In the present study retinoscopy, keratometry and ultrasonographic biometry were performed on 98 healthy equine eyes from 49 horses. The refractive state, corneal curvature (keratometry) and the axial location of all optical interfaces (biometry) were measured. The influences of breed, height at the withers, gender and age on values obtained and the comparison between the le...
Hibbs CD, Barrett PM, Dees DD.To determine intraocular pressure (IOP) reference intervals in eyes of healthy miniature donkeys (Equus africanus asinus) via rebound and applanation tonometry. Methods: Complete ophthalmic and physical examinations were performed by board-certified veterinary ophthalmologists. Inclusion criteria for animals participating in this study were dictated by the American Society for Veterinary Clinical Pathology (ASVCP) reference interval guidelines. Intraocular pressure estimates (TonoVet® and TonoPen XL® ) were obtained in both eyes. Forty animals (San Angelo group) received intramuscular xylazi...
Gialletti R, Marchegiani A, Valeriani T, Nannarone S, Beccati F, Fruganti A, Laus F.To describe the association of clinical and ultrasonographic (US) findings in horses affected by visual impairments, to estimate the most frequent ultrasonographic alteration as well importance and limits of US as a part of ophthalmic evaluation in equine patients. Methods: One-hundred-forty-five horses referred to the Veterinary Teaching Hospitals of the University of Perugia and Camerino for ocular problems were submitted to ophthalmic examination and ocular ultrasound. The following group of abnormalities was established: corneal alteration, cataract, synechiae, iris prolapse, anterior cham...
Gordon E, Stang BV, Heidel J, Poulsen KP, Cebra CK, Schlipf JW.To determine if corneal epithelial cell integrity is detrimentally affected by short-term administration of 1.0% morphine sulfate. Additionally, we sought to determine if topical 1.0% morphine applied to the equine cornea would result in ocular or systemic absorption. Methods: Six healthy horses. Methods: Morphine sulfate (1.0%) was applied topically to one eye every four hours for 72 h before horses were euthanized. Serum samples were collected at varying time points during the study and aqueous and vitreous humor were collected immediately after euthanasia. Morphine quantification in serum, ...
Flores AR, Azinhaga A, Pais E, Faria F, Nunes F, Gartner F, Amorim I.This report describes an ocular mast cell tumor in a 13-year-old female sport horse. Clinical examination revealed a solitary firm mass located in the ocular mucosa, protruding from behind the left lower eyelid. The lesion was surgically removed and submitted to histopathology. Microscopically, the mass was composed of sheets of well-differentiated neoplastic round cells circumscribed by delicate connective tissue. Positive Giemsa and Toluidine Blue staining confirmed the presence of cytoplasmic granules. Neoplastic cells showed strong membranous and mild diffuse cytoplasmic immunoreactivity f...
Wehrman RF, Gemensky-Metzler AJ, Zibura AE, Nyhart AB, Chandler HL.OBJECTIVE To determine the safety of topical administration of 1% atropine ophthalmic solution in healthy horses by objectively measuring gastrointestinal transit time. DESIGN Randomized, masked, controlled crossover study. ANIMALS 6 adult geldings. PROCEDURES Horses were randomly assigned (3/group) to first receive topical treatment of the left eye with 1% atropine or artificial tears solution; the right eye was left untreated. After 24 hours of treatment every 6 hours, 200 nontoxic beads were administered to each horse via nasogastric intubation and treatment frequency was decreased to every...
Michau TM.Glaucoma is a multifactorial neurodegenerative ocular disease leading to progressive loss of retinal ganglion cells and their axons that form the optic nerve, causing blindness. Knowledge of the pathogenesis and development of equine glaucoma is in its infancy compared with human glaucoma. Glaucoma occurs most commonly secondary to uveitis and may be underdiagnosed or misdiagnosed in horses suffering from uveitis. Recognition and clinical diagnosis of glaucoma in the horse is improved with clinician awareness and the availability of handheld tonometers. Therapy for glaucoma is aimed at decreas...
Estell K.Periocular neoplasia is common in horses. Treatment of the periocular skin and ocular adnexal structures can be technically challenging. Common neoplastic conditions, a treatment algorithm, surgical principles, and therapeutic modalities are reviewed. Regardless of the type of neoplasia found or the treatment that is applied, success is most likely when the neoplastic tumor is small.
Townsend WM.Examination of the lens is critical, particularly when evaluating horses with visual impairment or performing prepurchase examinations. To adequately evaluate the lens, the pupil must be pharmacologically dilated. A cataract is any lens opacity. The size, density, and position of a cataract determine the impact on vision. Cataracts may be congenital or inherited or occur secondary to trauma or equine recurrent uveitis. Surgical removal is the only treatment option for vision impairing cataracts, but careful selection of surgical candidates is critical for successful outcomes.
Wotman KL, Johnson AL.Many systemic diseases have ocular manifestations. In some cases, ocular abnormalities are the most obvious or first recognized sign of disease that prompts veterinary evaluation. In other cases, the systemic disease leads to secondary ocular changes that might lead to loss of vision or globe if not addressed. Therefore, recognition of ocular abnormalities that might result from systemic diseases is an essential skill for the equine practitioner. This article provides practitioners with information regarding the most common systemic diseases of horses in North America that have ocular manifest...
Ben-Shlomo G.Fundus is an anatomic term referring to the portion of an organ opposite from its opening, and the fundus of the eye is the back portion of the posterior segment of the globe, including the optic nerve, retina, and choroid. Clinically, the fundus can be visualized by direct or indirect ophthalmoscopy. Understanding the normal anatomy and appearance of the equine fundus is crucial for differentiating normal variations from abnormalities. This article reviews the normal anatomy and appearance of the equine fundus and discusses basic and advanced examination techniques. It also discusses common f...
Bellone RR.Advances in equine genetics and genomics resources have enabled the understanding of some inherited ocular disorders and ocular manifestations. These ocular disorders include congenital stationary night blindness, equine recurrent uveitis, multiple congenital ocular anomalies, and squamous cell carcinoma. Genetic testing can identify horses with or at risk for disease and thus can assist in clinical management. In addition, genetic testing can identify horses that are carriers and thus can inform breeding decisions. Use of genetic tests in management and breeding decisions should aid in reduci...
Scherrer NM, Lassaline M, Engiles J.To determine the characteristics of and prognosis for ocular and periocular hemangiosarcoma in horses. Methods: Six horses treated for ocular or periocular hemangiosarcoma. Methods: A retrospective review of medical records from 2007 to 2015 was performed to identify horses with a histologic diagnosis of ocular or periocular hemangiosarcoma. Signalment (age, sex, breed), duration of clinical signs, prior treatment, tumor size and location, medical and surgical treatment including postoperative chemotherapy, follow-up time, and outcome were obtained from medical records. Histopathology was revi...
Paschalis-Trela K, Cywińska A, Trela J, Czopowicz M, Kita J, Witkowski L.Equine ocular diseases pose a medical challenge due to long-lasting and cost-consuming therapies as well as economic issues associated with potential decrease in value of affected horses. The scale of the problem is significant but difficult to precisely define because epidemiological data is limited and lacks consistency in presentation. To date, no retrospective studies specifically investigating Arabian horses have been published. Results: The aim of this cross-sectional study was to investigate the prevalence of ocular lesions and define the ocular diseases present in Arabian horses from b...
Rushton JO, Kammergruber E, Tichy A, Egerbacher M, Nell B, Gabner S.Despite advances in therapy of corneal ulcerative diseases in horses, a vast number of cases require surgical intervention, due to poor response to treatment. Topical application of serum has been used for many years, based on its anticollagenolytic properties and the presence of growth factors promoting corneal wound healing. However, although other blood derived products i.e. platelet rich plasma (PRP), plasma rich in growth factors (PRGF) have been widely used in equine orthopaedics and in human ophthalmology, no reports of the effects of these blood derived products exist in equine ophthal...
Gilger BC.This article reviews the literature for studies describing advanced imaging of the equine eye as a reference for practitioners to help in the selection of image modalities, describe how to use the instruments, and help interpret the image findings. Indications for, technique of, and image interpretation of advanced image modalities such as ultrasound, computed tomography, MRI, optical coherence tomography, confocal microscopy, and angiography are reviewed. The article is organized anatomically, not by instrument, so that the reader will be able to quickly research ways to image specific diseas...
McMullen RJ, Fischer BM.Equine recurrent uveitis (ERU) is characterized by recurrent bouts of inflammation interrupted by periods of quiescence that vary in duration. There is little consensus on the clinical manifestations, the underlying causes, or the management. The 3 commonly recognized syndromes of ERU (classic, insidious, and posterior) do not accurately separate the clinical manifestations of disease into distinct categories. An accurate diagnosis and early intervention are essential to minimizing the effects of disease and preserving vision. There are multiple medical and surgical options for controlling ERU...
Ledbetter EC.Fungi are clinically important causes of ocular infections in the horse. Keratomycosis is the most common; however, a diverse range of mycotic infections, affecting numerous ocular tissues, may be encountered. Many equine mycoses are diagnostic and therapeutic challenges. Prompt and appropriate treatment is essential to minimize morbidity and reduce the likelihood of vision loss. Knowledge of the characteristics and properties of equine ophthalmology antifungal medications is essential to selecting an optimal treatment strategy, including selection of appropriate medication and effective admin...
Myrna KE.This article provides a brief, clinically relevant review of neurologic disorders of the eye. A description of the neuro-ophthalmic examination is provided. Stepwise descriptions of the most common neuro-ophthalmic abnormalities are provided along with common rule outs.
Grosås S, Østevik L, Revold T, Ottesen N, Ropstad EO.A uveal leiomyosarcoma of a horse is reported. There are few published reports of intraocular tumors in horses. Intraocular tumors challenge animal welfare by causing uveitis, glaucoma, and loss of vision. Knowledge regarding treatment of intraocular tumors with globe preservation is sparse, and further investigations on this topic are required.
Regnier A, Berton I, Concordet D, Douet JY.To assess the degree and duration of corneal anaesthesia provided by topical application of a non-ophthalmic 2% lidocaine gel in horses. Methods: Experimental, 'blinded', randomized prospective study. Methods: Twelve adult horses without relevant ocular abnormalities. Methods: Baseline corneal touch threshold (CTT) measurements were obtained bilaterally by use of a Cochet-Bonnet aesthesiometer just prior to topical treatment. A volume of 0.2mL of 2% lidocaine gel was administered in one randomly selected eye and the same volume of a viscous lubricant in the other eye to serve as control. The C...
Wright K, Ireland JL, Rendle DI.Horses are reported to return to a variety of disciplines following unilateral enucleation; however, owners of horses with ocular disease are frequently reluctant to consider the procedure. There is little published information investigating owners' attitudes towards, and satisfaction following, enucleation. Objective: To investigate the hypotheses: 1) horses return to their previous level of work following unilateral enucleation and 2) their owners are satisfied with the post-operative outcome. Methods: Retrospective case series with cross-sectional survey. Methods: Clinical records from eigh...
Yi NY, Davis JL, Salmon JH, Gilger BC.To determine ocular distribution and toxicity of a single injection of intravitreal triamcinolone acetonide (TA) in normal horses. Methods: Six adult horses, donated to North Carolina State University. Methods: Six horses were injected intravitreally with either 10, 20, or 40 mg (n = 2 each) of TA. The opposite eye of each horse was injected with balanced salt solution (BSS). Ocular toxicity was assessed by biomicroscopy, tonometry, indirect ophthalmoscopy, and electroretinogram. Aqueous humor (AH), vitreous humor (VH), and plasma samples were collected. Horses were euthanized 7 or 21 days aft...
The Journal of physiologyOctober 24, 2003
Volume 554, Issue Pt 3 791-801 doi: 10.1113/jphysiol.2003.054809
Kostyuk O, Birch HL, Mudera V, Brown RA.This study aimed to investigate the preferential collagen fibril alignment in unloaded and loaded tendons using elastic scattering spectroscopy. The device consisted of an optical probe, a pulsed light source (320-860 nm), a spectrometer and a PC. Two probes with either 2.75 mm or 300 microm source-detector separations were used to monitor deep and superficial layers, respectively. Equine superficial digital flexor tendons were subjected to ex vivo progressive tensional loading. Seven times more backscattered light was detected parallel rather than perpendicular to the tendon axis with the 2.7...
Herring IP, Pickett JP, Champagne ES, Troy GC, Marini M.OBJECTIVE: To determine the effect of topical 1% ophthalmic atropine sulfate on intraocular pressure (IOP) in ocular normotensive horses. Animals Studied Eleven clinically healthy horses. Procedures IOP was measured bilaterally twice daily, at 8 AM and 4 PM, for 5 days. No medication was applied for the first 2 days of the study. Thereafter, one eye of each horse was treated with 0.1 mL of topical 1% atropine sulfate ointment twice daily (7 AM and 7 PM) for 3 days. The contralateral eye served as a control. In eight of the horses, an additional IOP reading was taken 3 days following cessation ...
Meister U, Ohnesorge B, Körner D, Boevé MH.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...
Auer U, Moens Y.The production of a central eye to ease surgical access for intraocular surgery is generally dependent on the depth of anesthesia. The aim of this study was to evaluate the eyeball position under muscle relaxation with rocuronium during general anesthesia. Methods: Twenty horses, body weight 480 ± 62 kg; age 12.6 ± 6.2 years (mean ± SD) were anesthetised for various ophthalmic surgeries. Horses were premedicated with acepromazine, xylazine, and butorphanol intravenously and anesthesia induced with ketamine and diazepam. Anesthesia was maintained with isoflurane in 100% oxyge...
Barsotti G, Sgorbini M, Nardoni S, Corazza M, Mancianti F.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 ...
Giuliano EA, MacDonald I, McCaw DL, Dougherty TJ, Klauss G, Ota J, Pearce JW, Johnson PJ.Local photodynamic therapy (PDT) is a novel cancer therapy in veterinary ophthalmology. A prospective pilot study seeking to demonstrate proof of principle and safety for the treatment of equine periocular squamous cell carcinoma (PSCC) was therefore conducted. We hypothesized that surgical excision with adjunctive local PDT is an effective and safe treatment for equine PSCC. Methods: Nine horses (10 eyes) with PSCC were treated with surgical resection, local infiltration of resulting wound beds with 2-[1-hexyloxyethyl]-2-devinylpyropheophorbide-a (HPPH) and irradiation with 665-nm wavelength ...
Herrera HD, Duchene AG, Croxatto JO, Burgués N, Amusquibar H.Vascular tumors of the conjunctiva in the horse are rare. We present a unique case of an intravascular papillary endothelial hyperplasia of the conjunctiva. Methods: Horse. Methods: Case report. A 6-year-old-mare presented with a red mass in the conjunctiva of the left eye. After complete ophthalmologic examination the lesion was excised. The tissue was processed for light microscopy and studied histopathologically. Results: Pathologic examination revealed a nonencapsulated vascular lesion composed of confluent vascular spaces filled by multiple papillary structures composed of a central colla...
Reinstein SL, Lucio-Forster A, Bowman DD, Eberhard ML, Hoberg EP, Pot SA, Miller PE.A 4-year-old Hanoverian gelding was evaluated because of a mobile worm-like structure in the right eye. Results: Ophthalmologic examination of the right eye revealed a white, thin, coiled, mobile parasite, which was presumed to be a nematode, located in the ventral portion of the anterior chamber of the eye; there also were vitreal strands located temporally and inferiorly near the margin of the pupil. Results of ophthalmologic examination of the left eye were unremarkable. Results: The horse was treated with a neomycin-polymyxin B-dexamethasone ophthalmic solution applied topically (1 drop, q...
Trim CM, Colbern GT, Martin CL.Intraocular pressure was measured with a MacKay-Marg tonometer in eight horses following auriculopalpebral nerve block and topical application of lignocaine. Measurements were recorded before and after xylazine, 1.1 mg/kg intravenously, every two minutes for 16 minutes after administration of ketamine, 2.2 mg/kg intravenously, and after recovery from anaesthesia. Before xylazine, intraocular pressure was 17.1 +/- 3.9 and 18.4 +/- 2.2 mm Hg in the left and right eyes, respectively. Intraocular pressure tended to decrease after administration of xylazine and ketamine, with a significant decrease...
Holve DL.To determine the effect of sedation with detomidine on intraocular pressure (IOP) in standing horses and whether topical ocular application of anesthetic alters this effect. Methods: Clinical trial. Methods: 15 clinically normal horses. Methods: Horses were assigned to group 1 (n = 7) or 2 (8). Intraocular pressure measurements were obtained at baseline (before sedation) and 10 minutes after IV administration of detomidine (0.02 mg/kg [0.009 mg/lb]). Group 1 horses had an additional IOP measurement at 20 minutes after sedation. For group 2 horses, topical ocular anesthetic was administered 10 ...
Hazel SJ, Thrall MA, Severin GA, Lauerman LH, Lavach JD.Using routinely available clinical laboratory methods, aqueous humor samples were evaluated from 12 healthy dogs, 15 healthy cats, 7 healthy horses, and 6 healthy cows. Aqueous humor was almost acellular; cells that were present had degenerated beyond recognition. Protein concentration was low; only albumin was detectable on electrophoresis. Creatine phosphokinase and lactate dehydrogenase isoenzymes were not detected. Artifacts induced by sampling were insignificant compared with alterations in aqueous humor composition that occur with ocular diseases.
Launois T, González Hilarión LM, Barbe F, Leurquin C, Bihin B, Hontoir F, Dugdale A, Vandeweerd JM.We report a retrospective evaluation of intravitreal gentamicin (6 mg in 0.3 mL solution) injection in 71 horses with equine recurrent uveitis between 2010 and 2016. Aqueous flare and hyalitis were scored at the baseline in all horses, then at 15, 30, 60, 90, 180, 365, and 730 in 37, 46, 30, 25, 22, 18, and 11 horses, respectively. Forty-two animals had a global score of inflammation (sum of scores for aqueous flare and hyalitis) of zero at the last examination (number of re-examinations per horse ranged from 1 to 5). Among the 29 remaining horses, four were not reassessed after the interven...
Ramadan RO.The clinical features and pathology of an ocular melanoma in a young born-grey mare are described. The tumour, possibly arising on the cornea, invaded the eye and extra-orbital muscles. Histologically; it consisted predominantly of spindle-shaped and polygonal cells containing melanin.
Denis HM.Corneal disease is common in equine ophthalmology and requires vigilant monitoring and appropriate therapy to optimize the outcome. Many equine corneal diseases, particularly those that progress rapidly, may benefit from surgical intervention. These include descemetoceles, deep corneal lacerations and ulcers, corneal perforation/iris prolapse, ulcerative keratitis, corneal stromal abscesses, and corneoscleral neoplasia. Indications for corneal transplantation include optical, tectonic, therapeutic, and cosmetic purposes. Corneal transplantation is most often implemented in equine patients for ...
Wehrman RF, Gemensky-Metzler AJ, Zibura AE, Nyhart AB, Chandler HL.OBJECTIVE To determine the safety of topical administration of 1% atropine ophthalmic solution in healthy horses by objectively measuring gastrointestinal transit time. DESIGN Randomized, masked, controlled crossover study. ANIMALS 6 adult geldings. PROCEDURES Horses were randomly assigned (3/group) to first receive topical treatment of the left eye with 1% atropine or artificial tears solution; the right eye was left untreated. After 24 hours of treatment every 6 hours, 200 nontoxic beads were administered to each horse via nasogastric intubation and treatment frequency was decreased to every...
Wada S, Ode H, Hobo S, Niwa H, Katayama Y, Takatori K.To describe a case of superficial keratomycosis caused by Mortierella wolfii (M. wolfii) in a horse. Methods: A thoroughbred filly was presented with painful right eye of 2 days' duration. A superficial corneal ulcer was observed ventrally together with multifocal punctuate opacities axially. Samples were collected by swabbing and scraping the ulcerated lesion and submitted for microbiologic and cytologic examination. Results: Microscopic evaluation of debrided corneal tissue revealed the presence of nonseptate fungal hyphae, and culture of a corneal swab yielded fungal growth. Medical treat...
Miller C, Utter ML, Beech J.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 threshold (CTT...
Gilger BC, Davidson MG, Nadelstein B, Nasisse M.To determine clinical features of cystic granula iridica in horses and outcome of horses treated with an ophthalmic neodymium:yttrium-aluminum-garnet (Nd:YAG) laser. Methods: Retrospective study. Methods: 8 horses. Methods: An ophthalmic Nd:YAG laser was used to deflate cysts in all horses. Results: Horses were examined because of visual impairment (n = 5), decreased jumping performance (2), or head shaking (1). Clinical signs associated with cysts resolved in all horses after treatment. Short- and long-term complications did not develop, and cysts did not recur. Conclusions: Cystic granula ir...
Nunnery C, Pickett JP, Zimmerman KL.This report documents congenital stationary night blindness (CSNB) in two non-Appaloosa horse breeds (Thoroughbred and Paso Fino). History of vision impairment since birth, normal ocular structures on ophthalmic examination, and electroretinographic findings were consistent with CSNB. In one horse (Thoroughbred), a 9-year follow-up was carried out. In the Paso Fino, severe vision impairment from birth to approximately 1 year of age in both dim and bright light situations led to humane euthanasia and histopathologic confirmation of the disorder.
Spiess BM, Nyikos S, Stummer E, Sahin A, Naegeli H.To determine concentrations of dexamethasone in serum and urine of horses treated repeatedly with a topically administered ophthalmic dexamethasone preparation. Methods: 4 clinically normal horses (2 mares, 2 geldings). Methods: 0.1% dexamethasone ophthalmic ointment was administered to the left eye of each horse every 5 to 9 hours for 8 consecutive days, yielding an estimated cumulative dexamethasone dose of 6.4 microg/kg of body weight. Serum and urine samples were obtained before the first dexamethasone treatment, on days 4 and 8 of treatment, and 24, 48, and 96 hours after cessation of tre...
McMullen RJ, Davidson MG, Campbell NB, Salmon JH, Gilger BC.To determine appropriate intraocular lens (IOL) implant strength to approximate emmetropia in horses. Methods: 16 enucleated globes and 4 adult horses. Methods: Lens diameter of 10 enucleated globes was measured. Results were used to determine the appropriate-sized IOL implant for insertion in 6 enucleated globes and 4 eyes of adult horses. Streak retinoscopy and ocular ultrasonography were performed before and after insertion of 30-diopter (D) IOL implants (enucleated globes) and insertion of 25-D IOL implants (adult horses). Results: In enucleated globes, mean +/- SD lens diameter was 20.14 ...
Crispin SM.The iris is derived from interaction between neural crest tissue and the adjacent neuroectoderm of the optic cup. Developmental anomalies of the equine iris are common, and include congenital miosis, iris cysts, various manifestations of iris hypoplasia, heterochromia, and persistent pupillary membrane remnants. They may be found alone or in combination with other ocular defects.
Rayner SG, Van Zyl N.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...
Stine JM, Michau TM, Williams MK, Kuebelbeck KL, Stengard ME.Original study. Objective: To evaluate the effect of sedation with romifidine hydrochloride 1% (Sedivet: Boehringer-Ingelheim) on intraocular pressure (IOP) in the normal horse and horses with incidental ophthalmic findings as measured by applanation tonometry. Methods: Nineteen clinically normal horses (13 geldings, six mares) and eight horses (three geldings, five mares) with incidental ophthalmic findings were included in this study. Methods: All horses underwent complete ophthalmic examination with pharmacologic mydriasis a minimum of 2 weeks prior to IOP evaluation. Baseline intraocular p...
Labelle AL, Clark-Price SC.Effective delivery of local anesthesia is essential for successful standing surgical procedures in the horse. Local anesthesia can be used to facilitate examination of the eye, diagnostic procedures, therapeutic techniques, and surgical procedures. Understanding the relevant clinical anatomy and techniques for performing local anesthesia is critical to delivering successful local and regional anesthesia and analgesia.
May A, Gesell-May S, Müller T, Ertel W.Due to recent developments in artificial intelligence, deep learning, and smart-device-technology, diagnostic software may be developed which can be executed offline as an app on smartphones using their high-resolution cameras and increasing processing power to directly analyse photos taken on the device. Objective: A software tool was developed to aid in the diagnosis of equine ophthalmic diseases, especially uveitis. Methods: Prospective comparison of software and clinical diagnoses. Methods: A deep learning approach for image classification was used to train software by analysing photograph...
