The use of shotgun label-free quantitative proteomic mass spectrometry to evaluate the inflammatory response in aqueous humor from horses with uveitis compared to ophthalmologically healthy horses.

OBJECTIVE: The objective of this study was to use shotgun label-free tandem mass spectrometry (LF-MS/MS) to evaluate aqueous humor (AH) from horses with uveitis (UH) compared to ophthalmologically healthy horses (HH). ANIMALS STUDIED: Twelve horses diagnosed with uveitis based on ophthalmic examination and six ophthalmologically healthy horses (postmortem) purchased for teaching purposes. PROCEDURES: All horses received a complete ophthalmic examination and physical exam. Aqueous paracentesis was performed on all horses and AH total protein concentrations were measured with nanodrop (TPn) and refractometry (TPr). AH samples were analyzed with shotgun LF-MS/MS and proteomic data were compared between groups using Wilcoxon rank-sum test. RESULTS: A total of 147 proteins were detected, 11 proteins had higher abundance in UH, and 38 proteins had lower abundance in UH. Proteins with higher abundance included apolipoprotein E, alpha-2-macroglobulin (A2M), alpha-2-HS-glycoprotein, prothrombin, fibrinogen, complement component 4 (C4), joining chain for IgA and IgM, afamin, and amine oxidase. There were positive correlations between TPn (p = .003) and TPr (p = .0001) compared to flare scores. CONCLUSION: Differential abundance of A2M, prothrombin, fibrinogen, and C4 indicate upregulation of the complement and coagulation cascade in equine uveitis. Proinflammatory cytokines and the complement cascade have potential as therapeutic targets for equine uveitis.

Effect of gentamicin on CD3+ T-lymphocyte proliferation for treatment of equine recurrent uveitis: An in vitro study.

OBJECTIVE: The objective of the study was to determine the effect of gentamicin on CD3+ T-lymphocyte proliferation and cell viability using an in vitro cell culture model as a means of investigating the mechanism of action of low-dose intravitreal gentamicin injection. ANIMALS STUDIED: Three adult horses with no evidence of ophthalmic or systemic disease. PROCEDURE: Peripheral blood lymphocytes were treated with gentamicin at concentrations 37.5 µg/mL, 112.5 µg/mL, 187 µg/mL, 375 µg/mL, or 750 µg/mL then stimulated to proliferate with concanavalin A (ConA). 4',6-diamidino-2-phenylindole (DAPI) and carboxyfluoroscein succinimidyl ester (CSFE) were used as markers of cell viability and cell proliferation, respectively. Following 5-day culture, live cell counts and CSFE fluorescent intensity data were collected via automated cell count and flow cytometry. The experimental design was duplicated using preservative-free gentamicin and a proprietary brand formulation. Statistical analysis was performed using two-way ANOVA with Tukey's multiple comparison test. RESULTS: No statistically significant comparisons in CD3+ T-lymphocyte live cell counts and geometric mean fluorescent intensity of CSFE were identified between gentamicin concentrations or formulations. CONCLUSIONS: Gentamicin had no effect on equine peripheral blood CD3+ T-lymphocyte cell viability and proliferation in concentrations ranging from "safe" to "retinotoxic" in relation to intravitreal injection volumes. Low-dose intravitreal gentamicin may not suppress the Th1- and Th17-mediated immune response.

Limbal Squamous Cell Carcinoma in a Black Baldy Cow: Case Report and Surgical Treatment.

Objective: To document a case of limbal squamous cell carcinoma (SCC) in an adult Black Baldy cow treated with photodynamic therapy (PDT) as an adjunctive therapy following surgical excision. Animals Studied. One privately owned 8-year-old female, entire, Black Baldy cow. Procedures. A complete ophthalmic examination was performed on an adult Black Baldy cow for assessment of a mass affecting the left eye. Following a routine partial incision superficial lamellar keratectomy and conjunctivectomy under local analgesia using a Peterson retrobulbar block, photodynamic therapy was performed as an adjunctive treatment to lower the chance for recurrence and improve the prognosis for the globe. Results: Histopathologic analysis of the limbal mass was reported to be consistent with a squamous cell carcinoma, removed with clean margins. The patient was comfortable and visual with no signs of tumor recurrence 11 months after surgery. Conclusion: Superficial lamellar keratectomy and conjunctivectomy with adjunctive photodynamic therapy is an effective treatment for limbal squamous cell carcinoma and may be performed as an alternative to enucleation, exenteration, euthanasia, or slaughtering in cattle.

Prevalence, differences, and potential correlation to age, sex, breed, coat color, iris color, and geographic location in naturally occurring refractive errors in the normal equine eye from Germany and North Carolina.

PURPOSE: To evaluate the normal refractive state in horses in NCSU and ECMR and determine the prevalence of naturally occurring refractive errors and their association with breed, age, coat color, iris color, sex, and geographic location. METHODS: Horses from NCSU (January 2009-November 2012) and ECMR (January 2013-September 2016) underwent ophthalmic examination and streak retinoscopy. Location, color, breed, sex, and iris color were recorded. Gross and net refractive values for each meridian (horizontal and vertical), spherical refraction, astigmatism for both eyes, and anisometry were recorded, and statistical analyses were performed. RESULTS: There is excellent agreement in refraction between the eyes of the same horse (ICC = 0.89). The median net horizontal (H), vertical (V), and spherical refraction for the total population (n = 690) were H: +0.25 D (min. -6.50 D, max. +2.34 D), V: +0.25 D (min. -7.13 D, max. +2.75D), and spherical: +0.25 D (min. -6.82 D, max. +2.17 D), all with interquartile ranges of -0.25 to 0.25 D. Emmetropia (>-0.50 D and <+0.50 D; >-0.75 D and <+0.75 D) was present in 769/1380 eyes (55.7%) and 926/1380 eyes (67.1%), respectively. Anisometropia was present in 86/690 horses (12.5%). Sex, iris color, and location were significantly associated with refraction values, whereas age, breed, and coat color were not. CONCLUSIONS: Most eyes evaluated are emmetropic, or shifted myopically, with excellent agreement between eyes of the same horse. Sex, iris color, and geographic location appear to impact refraction in horses. SUPPORT: None.

Effects of corneoconjunctival transposition, posterior lamellar keratoplasty and modified deep lamellar endothelial keratoplasty on streak retinoscopy in equine cadaver eyes.

OBJECTIVE: Evaluate the effects of corneoconjunctival transposition (CCT), posterior lamellar keratoplasty (PLK) and modified deep lamellar endothelial keratoplasty (DLEK) on streak retinoscopy in equine cadaver eyes. METHODS: Intraocular pressure (IOP) was maintained at 25 ± 3 mmHg in 35 equine cadaver eyes. Streak retinoscopy was performed prior to (NO VISCO) and following (VISCO) intracameral injection of 1.0 ml of viscoelastic. Following optical coherence tomography (OCT), an axial CCT [n = 11] or PLK [n = 12], or peripheral DLEK [n = 12] was performed. Streak retinoscopy and OCT were repeated postoperatively. RESULTS: Postsurgical net meridional and spherical refraction for CCT [Horizontal (H): 3.4 (95% CI 2.4-4.4) diopters (D), p < .001, Vertical (V): 3.5 (95% CI 2.7-4.4) D, p < .001, Spherical: 3.5 (95% CI 2.6-4.3) D, p < .001] and PLK [H: 3.2 (95% CI 2.2-4.1) D, p < .001, V: 2.8 (95% CI 2.0-3.6) D, p < .001, Spherical: 3.0 (95% CI 2.2-3.8) D, p < .001] were significantly increased from presurgical (VISCO) values. No difference between presurgical (VISCO) and postsurgical values were identified for the DLEK. Postoperative OCT revealed space between anterior and posterior corneal grafts and corneal undulation associated with suture placement. CONCLUSION: Meridional and spherical refraction had a hyperopic shift following CCT and PLK, with a significantly higher value in the vertical meridian for the CCT. Pre- and postoperative refraction was not significantly different for the DLEK. This supports that the DLEK has a lesser effect on immediate postoperative refraction compared with CCT or PLK.

Clinical findings associated with blunt ocular trauma in horses: a retrospective analysis.

OBJECTIVE: Identify ocular findings associated with blunt ocular trauma to aid in differentiation from other equine ocular diseases. STUDY DESIGN: Retrospective case-control study. METHODS: Medical records of horses at the Equine Clinic Munich-Riem, Munich, Germany and Auburn University, College of Veterinary Medicine were reviewed. Age, sex, breed, laterality, and clinical findings on ophthalmic examination, as well as an observed (confirmed) or unobserved (suspected) history of trauma, were recorded. Statistical analysis was performed to identify any correlation between clinical signs and blunt ocular trauma. Fifty-nine clinical signs were evaluated, and their association with blunt ocular trauma and non-traumatic uveitis was determined. The frequency of clinical signs associated with non-traumatic uveitis was also reported. RESULTS: Fifty-five eyes affected with blunt trauma were included. The comparison group consisted of 233 eyes (168 horses) diagnosed with non-traumatic uveitis. The most frequent ocular findings after BOT included cataract (36/55, 65.5%), corneal edema (26/55, 47.2%), decreased intraocular pressure (23/55, 41.8%), aqueous flare (19/55, 34.5%), lens subluxation, luxation, or lens loss (18/55, 32.7%), fibrin in the anterior chamber (18/55, 32.7%), hyphema (16/55, 29.1%), peripapillary depigmentation ("butterfly lesion") (16/55, 29.1%), conjunctival hyperemia (16/55, 29.1%), corneal fibrosis (15/55, 27.3%), corpora nigra avulsion (14/55, 25.5%), blepharospasm (13/55, 23.6%), and iridodialysis (11/55, 20.0%). CONCLUSIONS: The characteristic pattern of ocular signs associated with blunt ocular trauma may assist in differentiation from other types of uveitis and may improve interpretation of ocular lesions identified during pre-purchase examinations. This study also represents the first peer-reviewed documented and photographed cases of iridodialysis in the horse.

Clinical and pathologic evaluation of chorioretinal lesions in wild owl species.

OBJECTIVE: Investigate histopathology and spectral-domain optical coherence tomography (OCT) imaging of wild owls with chorioretinitis and identify any potential correlation with an infectious etiology. MATERIALS AND METHODS: Ophthalmic examination and retinal OCT imaging were performed on fifteen great horned (Strix varia) and barred (Bubo virginianus) owls (30 eyes) with chorioretinitis and five owls with normal eyes (10 eyes). Testing to investigate the presence of potential infectious diseases included a complete blood count, biochemistry, protein electrophoresis, West Nile virus (WNV) plaque reduction neutralization test, Toxoplasma gondii modified direct agglutination test, WNV RT-PCR, and Avian Influenza RT-PCR. A necropsy was performed on all owls, including ocular histopathology. RESULTS: Fundus lesions included retinal detachment (7/15 owls), depigmented lesions (12/15), pigment clumping (8/15), and retinal tear (4/15). All birds were negative for WNV and Avian Influenza on RT-PCR. Of the owls with chorioretinitis, 3/15 were seropositive for WNV and 7/15 for T. gondii. Optical coherence tomography of 25/30 affected eyes revealed outer retinal lesions (19/25 eyes), retinal detachment (16/25), and retinal tears (3/25). Histopathological examination revealed outer nuclear layer atrophy (19/30 eyes), retinal detachment (18/30), retinal tears (7/30), suprachoroidal hemorrhage (12/30), scleral rupture (3/30), and ossicle fracture (3/30). CONCLUSIONS: Although 20% of birds were seropositive for WNV and 46.6% for T. gondii, histopathologic findings supported that the posterior segment lesions in the study group were likely due to blunt ocular trauma rather than an infectious etiology. The results of OCT imaging and histopathology documented retinal changes most consistent with blunt ocular trauma.

Keratometry, biometry, and prediction of intraocular lens power in adult tigers (Panthera tigris).

OBJECTIVE: To calculate the necessary pseudophakic intraocular lens (IOL) power to approximate emmetropia in adult tigers. ANIMALS: 17 clinically normal adult tigers. PROCEDURES: 33 eyes of 17 clinically normal adult tigers underwent routine ophthalmic examination and B-scan ultrasonography while anesthetized for unrelated procedures. Specific ultrasound data (globe measurements and corneal curvature) and estimated postoperative IOL positions were utilized to calculate predicted IOL power by use of Retzlaff and Binkhorst theoretical formulas. Applanation tonometry and refraction were also performed. RESULTS: Mean ± SD axial globe length was 29.36 ± 0.82 mm, preoperative anterior chamber depth was 7.00 ± 0.74 mm, and crystalline lens thickness was 8.72 ± 0.56 mm. Mean net refractive error (n = 33 eyes) was +0.27 ± 0.30 diopters (D). By use of the Retzlaff formula, mean predicted IOL power for the postoperative anterior chamber depth (PACD), PACD - 2 mm, and PACD + 2 mm was 43.72 ± 4.84 D, 37.62 ± 4.19 D, and 51.57 ± 5.72 D, respectively. By use of the Binkhorst equation, these values were 45.11 ± 4.91 D, 38.84 ± 4.25 D, and 53.18 ± 5.81 D, respectively. Mean intraocular pressure for all eyes was 14.7 ± 2.69 mm Hg. CLINICAL RELEVANCE: The calculated tiger IOL was lower than reported values for adult domestic felids. Further studies evaluating actual PACD and pseudophakic refraction would help determine the appropriate IOL power to achieve emmetropia in this species.

Comparison of image quality of corneal and retinal optical coherence tomography using sedation and general anesthesia protocols with or without retrobulbar anesthesia in horses.

OBJECTIVE: To compare image quality and acquisition time of corneal and retinal spectral domain optical coherence tomography (SD-OCT) under 3 different sedation-anesthesia conditions in horses. ANIMALS: 6 middle-aged geldings free of ocular disease. PROCEDURES: 1 randomly selected eye of each horse was evaluated via SD-OCT under the following 3 conditions: standing sedation without retrobulbar anesthetic block (RB), standing sedation with RB, and general anesthesia with RB. Five regions of interest were evaluated in the cornea (axial and 12, 3, 6, and 9 o'clock positions) and fundus (optic nerve head). Three diagnostic scans of predetermined quality were obtained per anatomical region. Image acquisition times and total scans per site were recorded. Corneal and retinal SD-OCT image quality was graded on a subjective scale from 0 (nondiagnostic) to 4 (excellent). RESULTS: Mean values for the standing sedation without RB, standing sedation with RB, and general anesthesia conditions were 24, 23, and 17, respectively, for total cornea scan attempts; 23, 19, and 19 for total retina-scan attempts; 14.6, 13.2, and 9.2 minutes for total cornea scan time; 19.1, 9.2, and 13.0 for total retina scan time; 2.0, 2.3, and 2.5 for cornea grade; and 2.7, 2.9, and 2.5 for retina grade. CONCLUSIONS AND CLINICAL RELEVANCE: The RB facilitated globe akinesia and improved the percentage of scans in frame and region of interest accuracy for retinal imaging via OCT in horses. Retrobulbar blocks improved clinical image acquisition while minimizing motion artifact.

Effects of Intravenous Flunixin Meglumine, Phenylbutazone, and Acupuncture on Ocular Pain Scores in the Horse: A Pilot Study.

In this controlled, blinded, randomized block pilot study, the main objective was to evaluate the effectiveness of intravenous flunixin meglumine, phenylbutazone, and acupuncture on ocular pain relief using a multifactorial pain scale in the horse. Four experimental horses underwent corneal epithelial debridement in four sessions, when a randomly selected treatment or a control was used. All horses were pain scored before corneal wounding, then at 18 time points, when 11 parameters were allocated. Differences in the area under the curve of pain scores between the treatment groups were analyzed using a paired t-test. Corneal pain was significantly reduced by the third postoperative day (P = .03) when all 11 parameters were considered. Five ocular signs showed significant differences between treatments and proved to be good indicators of ocular pain. The other parameters (heart rate, corneal touch threshold, respond to palpation, and three behavioral parameters) were determined to be irrelevant when evaluating the degree of pain. When considering the five ocular signs, the lowest pain score was attributed to the flunixin meglumine group (1114), followed by the electroacupuncture group (1356), the phenylbutazone group (1397), and the control group (1580). There were significantly lower pain scores (P = .01) in the flunixin meglumine group when compared with those recorded in the control group during the first 46 hours. Flunixin meglumine was the most effective treatment at reducing ocular pain in the horse. In the future, a reduction in the number of pain score parameters and more precisely defined image evaluation criteria could be used.

Descemet's membrane detachments, ruptures, and separations in ten adult horses: Clinical signs, diagnostics, treatment options, and preliminary results.

OBJECTIVE: To describe the clinical presentation, diagnostic imaging results, and treatment outcomes of a series of presumed spontaneous Descemet's membrane detachments (DMD), ruptures, or separations (DMRS) in the adult horse. ANIMALS STUDIED: Ten adult horses of various breeds with DMD or DMRS. PROCEDURES: Descemet's membrane detachments/DMRS were diagnosed via slit lamp biomicroscopy, ultrasound biomicroscopy (UBM), and/or optical coherence tomography (OCT). Penetrating keratoplasty (PK) with heterologous corneal donor tissue (n = 1), superficial lamellar keratectomy, and Gundersen inlay flaps alone (GF, n = 1) or with subsequent intracamerally assisted corneal tissue welding (CTW, n = 2), or CTW alone (n = 5) were performed in 9/10 horses. One horse underwent spontaneous resolution (n = 1). RESULTS: Ten horses were diagnosed with either unilateral DMD (n = 4) or DMRS (n = 6). Seven of ten eyes remained visual during the follow-up period (8.16 ± 6.57 months). Graft transparency was good for the eye treated with PK. The horse that underwent GF alone was functionally blind due to persistent corneal edema. The clinical signs resolved in 3/5 horses that underwent CTW alone, but 2/5 eyes were enucleated due to corneal perforation. Both eyes treated with combined GF/CTW had significant corneal clearing with one having evidence of reattachment on UBM and OCT. CONCLUSIONS: Descemet's membrane detachments separations presents differently than typical DMD and advanced corneal imaging modalities may aid in their diagnosis. Corneal tissue welding using infraCG as the photosensitive agent, or in combination with Gundersen inlay flaps, represents a feasible treatment option for management of equine DMD/DMRS as described in the present case series.

Sustained-release voriconazole-thermogel for subconjunctival injection in horses: ocular toxicity and in-vivo studies.

BACKGROUND: Keratomycosis is a relatively common, sight threatening condition in horses, where treatment is often prolonged and costly. Subconjunctival (SCo) injections offer less resistance to drug diffusion than the topical route, resulting in better penetration to the ocular anterior segment. Voriconazole, a second generation triazole antifungal, is effective against common fungal organisms causing keratomycosis. If combined with a thermogel biomaterial, voriconazole can be easily injected in the SCo space to provide sustained drug release. The purpose of this study was to evaluate the drug concentrations in the anterior segment and clinical effects after SCo injections of voriconazole-containing thermogel: poly (DL-lactide-co-glycolide-b-ethylene glycol-b-DL-lactide-co-glycolide) (PLGA-PEG-PLGA) in healthy equine eyes. RESULTS: Voriconazole aqueous humor (AH) and tear concentrations were compared between 6 horses, receiving 1% voriconazole applied topically (0.2 mL, q4h) (Vori-Top) or 1.7% voriconazole-thermogel (0.3 mL) injected SCo (Vori-Gel). For the Vori-Gel group, voriconazole concentrations were measured in AH and tears at day 2 and then weekly for 23 days, and at day 2 only for the Vori-Top group. Ocular inflammation was assessed weekly (Vori-Gel) using the modified Hackett-McDonald scoring system. Ocular tissue concentrations of voriconazole following SCo 1.7% voriconazole-thermogel (0.3 mL) injections were evaluated post euthanasia in 6 additional horses at 3 different time points. Three horses received bilateral injections at 2 h (n = 3, right eye (OD)) and 48 h (n = 3, left eye (OS)) prior to euthanasia, and 3 horses were injected unilaterally (OS), 7 days prior to euthanasia. Voriconazole-thermogel was easily injected and well tolerated in all cases, with no major adverse effects. On day 2, drug concentrations in tears were higher in the Vori-Top, but not statistically different from Vori-Gel groups. For the Vori-Gel group, voriconazole was non-quantifiable in the AH at any time point. Total voriconazole concentrations in the cornea were above 0.5 µg/g (the target minimum inhibitory concentration (MIC) for Aspergillus sp.) for up to 48 h; however, concentrations were below this MIC at 7 days post treatment. CONCLUSIONS: Voriconazole-thermogel was easily and safely administered to horses, and provided 48 h of sustained release of voriconazole into the cornea. This drug delivery system warrants further clinical evaluation.

Bilateral Phacoemulsification in an African Elephant (Loxodonta africana).

A 37-year-old bull African elephant (Loxodonta africana) at the North Carolina Zoo (NCZ) was diagnosed with bilateral cataracts leading to behavioral changes and significant weight loss secondary to functional blindness. On initial examination, a weight loss of 234 kg, a mature cataract in the right eye, and a focal cataract in the left eye were diagnosed. Ultrasound and electroretinography (ERG) indicated normal retinal attachment and both eyes were viable candidates for surgery. After careful planning and behavioral training, the left cataract was surgically removed via phacoemulsification and irrigation/aspiration. The right eye subsequently developed a ventral lens subluxation, and phacoemulsification and irrigation/aspiration were performed six months after the first procedure. Four years after surgery, menace response, palpebral reflex, dazzle reflex, and pupillary light reflexes were present in both eyes. Body weight was 5,515 kg, 88kg more than at the time of the second surgery. This is the first published report of an African bull elephant undergoing bilateral cataract removal using phacoemulsification and irrigation/aspiration. The lack of significant postoperative inflammation and uneventful recovery of the elephant suggests that this surgical procedure along with proper preoperative planning and postoperative medical management can be a safe and effective treatment option for elephants with cataracts.

Intravitreal injection of low-dose gentamicin for the treatment of recurrent or persistent uveitis in horses: Preliminary results.

BACKGROUND: Despite appropriate medical therapy, many horses with equine recurrent uveitis continue to suffer from recurrent bouts of inflammation. Surgical intervention via the pars plana vitrectomy or suprachoroidal cyclosporine implant placement may control and/or prevent recurrences, however, these procedures may be contraindicated, unavailable, or declined by an owner. Thus, an effective adjunctive treatment option may help to improve the clinical outcomes in those situations. There are several anecdotal reports on the use of intravitreal gentamicin injections, but to date, no data evaluating the complication rate and/or treatment effect following this treatment have been published. Thus, the aim of this prospective study was to describe the intravitreal gentamicin injection technique, describe the associated peri-injection (within 24 h) and post-injection (30 to 780 days) complications, and to report the effects of the injection on the clinical signs of uveitis. Additionally, evaluation of the systemic and ocular Leptospira-status, and its effect on the treatment outcome was performed. A total of 86 horses of various ages, breeds, and gender presenting with recurrent or persistent uveitis were treated via intravitreal injection of 4 mg of undiluted gentamicin (0.04 ml, Genta 100, 100 mg/ml in 35 horses) or preservative-free gentamicin (0.05 ml, 80 mg/ml in 52 horses) under sedation and local anesthesia. All 86 horses were observed for immediate peri-injection and post-injection complications. Response to therapy was evaluated in 59 of the 86 horses (follow-up: 30 to 780 days). RESULTS: Peri-injection complications consisted of subconjunctival (26/86; 30.2%) or intracameral hemorrhage (4/86; 4.7%); both of which completely resolved within 5 days. Post-injection complications consisted of cataract formation/maturation (5/59 horses, 8.5%) and diffuse retinal degeneration (3/59 eyes 5.1%). The majority of horses 52/59 (88.1%) with a minimum follow-up period of 30 days were controlled (absence of recurrent or persistent inflammation) at their last recheck examination. Recurrent inflammation was documented in 5/59 (8.5%) horses and persistent inflammation was diagnosed in 2/59 (3.4%) horses. CONCLUSIONS: Intravitreal injection of low-dose gentamicin shows promise at controlling different types and stages of uveitis. The ability of intravitreal injections of low-dose gentamicin (4 mg) to control persistent and recurrent inflammation warrants further investigation.

Modified lamellar keratoplasties for the treatment of deep stromal abscesses in horses.

OBJECTIVE: To describe a surgical modification of deep lamellar endothelial keratoplasty (DLEK) and posterior lamellar keratoplasty (PLK) procedures, to facilitate surgery on standing horses under-sedation. ANIMALS STUDIED: Four client-owned horses, for which the owners declined surgery under general anesthesia, underwent standing corneal lamellar keratoplasty procedures for the treatment of deep corneal stromal abscesses. PROCEDURES: All four horses were placed in stocks and sedated with detomidine. Local eyelid and retrobulbar blocks were performed to provide local analgesia and akinesia, and each horse's head was stabilized and supported by soft pads placed on a mobile cart. Deep lamellar endothelial keratoplasties (DLEKs) and posterior lamellar keratoplasties (PLKs) were performed on two horses each, for the treatment of deep stromal abscesses (DSA). Following the first DLEK, a mid-stromal two-step anterior lamellar keratectomy modification was used to facilitate rapid closure of the anterior chamber immediately following removal of the abscess. RESULTS: Each of the four horses had similar cosmetic and postoperative visual outcomes, compared to previously published results. Intra-operative complications were most prevalent in the first DLEK case (i.e., focal iris and lens damage and postoperative anterior chamber collapse) and were all but eliminated in the remaining three cases. Similar to previously reported findings, greater postoperative corneal fibrosis was observed in the DLEK cases. CONCLUSIONS: In horses with deep stromal or endothelial abscesses, for which general anesthesia is not an option, both the modified DLEK and PLK corneal procedures may be performed as an alternative to enucleation on the standing, sedated horse.

Clinical, histopathological and immunohistochemical characterization of a novel equine ocular disorder: heterochromic iridocyclitis with secondary keratitis in adult horses.

OBJECTIVE: To describe the clinical, histopathologic and immunohistochemical characteristics of an equine ocular inflammatory disease resulting in anterior uveitis and corneal endothelial inflammation associated with iris pigment dispersion and retrocorneal fibrous membrane (RFM) formation. DESIGN: Retrospective study. ANIMALS STUDIED: Sixteen horses with evidence of pigmented keratic precipitates (KPs), corneal edema, and/or iris depigmentation. Information collected from the medical records included signalment, clinical signs, prereferral treatment duration and response to therapy, ophthalmic examination findings, postreferral treatment, response to therapy, and outcome. RESULTS: Twenty-one eyes from 16 horses were affected. Age ranged between 9 and 25 years (Average 16.1 years). Blepharospasm, epiphora, and/or corneal opacification were the first clinical signs noted. At the time of referral pigmented KPs, corneal edema, iridal depigmentation, and retrocorneal membranes were commonly seen. Treatment included topical and/or systemic anti-inflammatories and antibiotics with variable response. Reduction or cessation of anti-inflammatory therapy resulted in worsening of clinical signs and disease progression. Eight eyes ultimately required enucleation. Histopathology changes include iridal pigment loss and dispersion, RFM formation, and keratitis. Variable degrees of lymphoplasmacytic inflammation were dominated by T-cells within the corneal stroma, RFM, iris, and ciliary body with occasional multinucleated giant cells. CONCLUSIONS: Heterochromic iridocyclitis with secondary keratitis (HIK) is characterized by uveal inflammation with pigment dispersion and suspected corneal endothelial dysfunction. Horses being treated for HIK require diligent and frequent follow-up examinations in combination with aggressive local immune suppression to control the disease. However, HIK may not respond to therapy and enucleation may ultimately be required to ensure the horse's comfort.

The effect of 1% tropicamide-induced mydriasis and cycloplegia on spherical refraction of the adult horse.

OBJECTIVES: To determine the effects of tropicamide 1% on the refractive state of the adult equine globe and identify the most appropriate time period (in relation to mydriasis) to perform streak retinoscopy. ANIMALS STUDIED: Eight university-owned mares of various ages and breeds. PROCEDURES: Topical tropicamide 1% was applied to one randomly selected eye from each of the horses to induce mydriasis and cycloplegia. The contralateral eyes served as controls. Streak retinoscopy and pupillometry were performed prior to, and every 5 min after tropicamide 1% installation for 90 min. RESULTS: All values are expressed as mean ± SD. Both horizontal (2.8 ± 0.74 mm) and vertical (7.3 ± 1.29 mm) mean pupil diameters increased significantly (P < 0.04) in the treatment eyes compared with the control eyes (horizontal [0.48 ± 0.85 mm] and vertical [1.06 ± 1.31 mm] pupil diameter). No significant differences in the refractive states of the treatment (horizontal: +0.25 ± 0.43 D and vertical: +0.41 ± 0.37 D) or control (horizontal: +0.34 ± 0.39 D and vertical: +0.41 ± 0.37 D) eyes were identified at any time point. Three of the eight treatment eyes demonstrated blurry or reversing streak reflexes during streak retinoscopy evaluation following the application of topical tropicamide 1%. CONCLUSIONS: While these reflexes did not significantly influence streak retinoscopy results, their presence may subjectively influence a novice retinoscopist's ability to obtain accurate results. Therefore, optimal streak retinoscopy results may be obtained prior to, or 40- to 45-min following the application of topical tropicamide 1%, once near-maximal dilation has been achieved.

Phacoemulsification and +14 diopter intraocular lens placement in a Saddlebred foal.

A 2-month-old, 110-kg Saddlebred filly presented for evaluation of bilateral cataracts. A hypermature cataract in the left eye (OS) and an incipient nuclear cataract in the right eye (OD) were diagnosed. Electroretinography and ocular ultrasound revealed no contraindications for surgical removal of the cataractous lens OS. Phacoemulsification and implantation of a +14 diopter (D) intraocular lens (IOL) OS were performed at 4 months of age without complication, with the exception of a partial iridectomy performed on a small iris section that prolapsed through the corneal incision. Complete ophthalmic examinations, including ocular ultrasound and streak retinoscopy, were performed 1, 2, 6 weeks, 4 months, 1, and 2 years postoperatively. Diffuse corneal edema and a superficial corneal ulcer developed OS during the early postoperative period and resolved without complication. Dyscoria was identified owing to anterior synechia of the dorsomedial iris at the incision site. Two years after surgery, menace response, palpebral reflex, dazzle reflex, and pupillary light reflexes were present in both eyes (OU). The IOL remained centrally positioned within the capsule, with mild anterior tilting of the superior portion of the IOL and mild fibrosis of the lens capsule. The postoperative net refractive error was +0.31 D OS. Based on this report, a +14 D IOL may be the appropriate choice following lens extraction in a foal to achieve refraction near emmetropia at maturity. To our knowledge, this is the first report of phacoemulsification and IOL implantation in a foal with long-term follow-up.

Diode laser endoscopic cyclophotocoagulation in the normal equine eye.

OBJECTIVE: To determine the clinical and histologic effects of diode endoscopic cyclophotocoagulation (ECP) in the phakic equine eye. ANIMALS STUDIED: Phase I: 10 equine cadaver eyes. Phase II: four normal adult horses. PROCEDURES: Phase I: ECP probe angle of reach (AR) was determined. Multiple ECP energy levels: 0.75, 0.90, 1.05, 1.20, 1.35, 1.50 J, and the resulting visible and histologic ciliary process changes were evaluated. Phase II: Ocular quadrants were treated with ECP at 0.90, 1.14, 1.38 J, and a control. The contralateral eye underwent a sham operation. Tissue changes (clinical and histologic) were evaluated. RESULTS: Phase I: Mean combined AR was 162 ± 29 degrees. Mean visible tissue scores: 2.60 ± 0.58 (0.75 J) to 5.04 ± 0.30 (1.50 J) from possible total of 6. Tissue 'popping' was observed at 1.50 J. Histologic ciliary tissue damage was present at all settings. Phase II: Mean visible tissue scores: 2.90 ± 0.48 (0.90 J), 3.61 ± 0.57 (1.14 J), and 4.52 ± 0.56 (1.38 J). Tissue 'popping' was observed at 1.38 J. Histologic ciliary tissue damage was present at all settings. Clinical effects included acute inflammation, intraocular pressure reduction, cataract formation, corneal edema, corneal ulceration, and postoperative ocular hypertension. CONCLUSIONS: Diode ECP between 0.90 and 1.14 J is a potential treatment option for glaucoma in horses based on visible tissue effects and target ciliary epithelium damage. Iatrogenic cataract development may limit the use of an anterior chamber approach in phakic horses. Supported in part by an ACVO VAF grant.