Simon A. Pot

Corneal collagen cross-linking (CXL) for the treatment of melting keratitis in cats and dogs: a pilot study

OBJECTIVE UV-A/riboflavin cross-linking (CXL) of corneal collagen fibers is an established, highly promising therapy for corneal melting in physician-based ophthalmology. A prospective pilot study was conducted to demonstrate proof of principle of this novel method for the treatment of melting corneal ulcers in dogs and cats. PROCEDURES After obtaining owner consent, CXL was performed in three cats and three dogs with corneal melting, which either affected the entire corneal surface or was resistant to conventional antibiotic and anticollagenolytic therapy, and affected parts or all of the corneal surface. Medical therapy was continued in all patients. The available follow-up ranged from 2 to 22.5 months and involved slit-lamp examination, fluorescein staining, and photographic documentation during all rechecks. RESULTS Surgical stabilization of the cornea was not necessary in any case, because progression of corneal melting was arrested in all cases within 1-20 days of CXL treatment. Corneal re-epithelization occurred within 7-40 days in all eyes. At 40 days after CXL, all eyes presented a quiescent corneal state without signs of active inflammation and with beginning scar formation. The complications observed in three of the six animals included a corneal sequestrum, superficial corneal stromal pigmentation, and bullous keratopathy. CONCLUSIONS This study shows the feasibility of CXL to treat progressive corneal melting in veterinary patients. CXL may represent a cost-efficient and safe alternative therapy in the treatment for corneal melting in veterinary ophthalmology. More investigations comparing the effectivity and complication rate of CXL to those of standard medical treatment are necessary.

Equine keratomycosis in Switzerland: A retrospective evaluation of 35 horses (January 2000–August 2011)

REASON FOR PERFORMING STUDY Keratomycosis is a severe disease in horses. Geographical differences in fungi causing keratomycosis and susceptibility of the organisms to antifungal drugs exist but few previous publications on this disease originate from Europe. OBJECTIVE To retrospectively compare the clinical data of 36 eyes with keratomycosis, diagnosed in 35 horses between January 2000 and August 2011 at the Vetsuisse Faculty of Switzerland. Case history, season, prior treatment, clinical appearance, surgical and medical treatment, treatment duration, and globe survival were evaluated. STUDY DESIGN Retrospective case series. METHODS Medical records of horses with a definitive cytological or histological diagnosis of keratomycosis were reviewed. RESULTS Thirty-one of 36 eyes (86.1%) presented with ulcerative keratitis, 2/36 (5.55%) had diffuse corneal infiltration, 2/36 (5.55%) had superficial punctate keratitis and 1/36 (2.8%) had a fluorescein-negative fungal plaque. Two of 6 fungal cultures produced Aspergillus spp. Thirty eyes received medical and surgical treatment, while 3 eyes were treated medically only. In 3 horses the globe was removed at the time of first presentation. Sex, age, prior treatment with antimicrobials or steroids, or type of surgical approach did not significantly influence the outcome. Twenty-three of 36 eyes (63.9%) were at least partially visual, 11/36 eyes (30.5%) were enucleated and 2 horses (2/36 eyes, 5.6%) were subjected to euthanasia. Treatment protocols were compared in the 31 eyes with ulcerative keratitis. In this group, 3/31 globes were immediately enucleated, 16/31 eyes were treated topically with voriconazole or voriconazole/fluconazole and 12/31 with other antifungal drug combinations. The different medication protocols did not significantly affect the outcome. CONCLUSIONS There were no significant differences in outcome between different medical treatment protocols or types of surgical approach. POTENTIAL RELEVANCE Future studies in central Europe should focus on the identification of fungal pathogens, susceptibility patterns and the efficacy of antifungal drug therapies.

Corneal collagen cross-linking as treatment for infectious and noninfectious corneal melting in cats and dogs: results of a prospective, nonrandomized, controlled trial.

OBJECTIVE UV-A/Riboflavin cross-linking of corneal collagen fibers (CXL) is a highly promising therapy for corneal melting in humans. A prospective interventional, nonrandomized, controlled study was conducted to compare the stabilizing effect of CXL treatment on melting keratitis in dogs and cats and the complication rate of CXL to those of standardized intensive medical treatment. PROCEDURES Forty-nine eyes with melting keratitis were included in the study between October 2009 and October 2012. All eyes were treated according to the same medical treatment protocol. Nineteen eyes were CXL-treated, and 30 eyes were not. Follow-up included slit-lamp examination, fluorescein staining, ulcer size measurement, stromal stability evaluation, photographic documentation, and documentation of complications. RESULTS Five of 19 eyes in the CXL group and 9/30 eyes in the control group required rescue stabilization due to continued melting. Seven of the nine control group corneas stabilized after rescue CXL treatment. At initial presentation, the ulcers in the canine CXL group were significantly deeper and larger than in the control group. Ulcer deepening during follow-up was more pronounced in the canine control group than in the canine CXL group. CXL treatment-related complications were not observed. CONCLUSIONS Based on the similar failure rates in the control and CXL treatment groups despite the poorer initial situation in the CXL group, the tendency for the ulcers in the control group to deepen and the stabilization of all corneas receiving CXL rescue treatment, we believe that CXL has its place as an adjunctive therapy for melting keratitis in veterinary ophthalmology.

Evaluation of the conjunctival fungal flora and its susceptibility to antifungal agents in healthy horses in Switzerland

OBJECTIVE To characterize the conjunctival fungal flora and to determine the susceptibility of 2 isolated molds to antifungal drugs in samples of 64 healthy horses from The National Stud in Switzerland. PROCEDURE Conjunctival cytobrush samples were collected from both eyes of 64 ophthalmologically normal horses in August 2012 and subsequently cultured on Sabourauds agar medium. Growing fungi were identified and counted. Etests or broth microdilution tests for Aspergillus fumigatus and Eurotium amstelodami were carried out to determine antifungal drug sensitivity. These species had previously been detected in samples from eyes with keratomycosis in Switzerland. Minimal inhibitory concentrations (MICs) for voriconazole, fluconazole, itraconazole, amphotericin B, and miconazole were recorded. RESULTS Fifty-nine of the horses were tested positive for fungal growth from at least one eye (92%). Eleven genera of fungi were identified. The most common fungal genera were Alternaria, Eurotium, Rhizopus, and Cladosporium. Aspergillus spp. and Penicillium spp. were isolated frequently, while no Fusarium spp. was found. In only 2 cases, yeasts were identified as Candida guilliermondii. For certain fungal species, the type of bedding and housing appeared to influence their prevalence. Susceptibility testing of A. fumigatus showed lowest MICs for voriconazole, E. amstelodami for voriconazole and itraconazole. High MICs for fluconazole were detected for all tested fungi while MICs for amphotericin B and miconazole were variable. CONCLUSIONS A large range of fungal mold species was identified including A. fumigatus and E. amstelodami, which have been causative agents of keratomycosis in Switzerland. Best in vitro susceptibility results for these two species were obtained for voriconazole.

Treatment of bullous keratopathy with corneal collagen cross-linking in two dogs

OBJECTIVE Corneal collagen cross-linking with riboflavin and UV-A (CXL) decreases corneal oedema and increases visual acuity in human patients with bullous keratopathy. Presumed mechanisms are an increase in collagen packing density and a reduction in stromal swelling pressure. We present two cases in which CXL was used to treat bullous keratopathy in dogs. PROCEDURES Four eyes of two dogs with painful bullous keratopathy-induced corneal erosions that were resistant to prior therapy were treated with CXL. Both corneas of the second patient were dehydrated to ± 400 μm corneal thickness using topical 70% glycerol solution immediately prior to CXL. Follow-up included slit-lamp examination, fluorescein staining and photographic documentation in both cases and high-resolution ultrasound examination in the second patient. RESULTS All four eyes were comfortable and fluorescein negative at 1-week post-CXL and remained so for the rest of the follow-up period (17.5 months for case 1 and 6 months for case 2). The owner of the first patient reported a less oedematous cornea and improvement in vision that lasted for 6 months. Despite a reported lack of improvement in vision in the second patient, corneal thickness initially decreased, but was back at baseline thickness at the 4-month recheck. CONCLUSIONS Similar to humans, CXL might become a useful treatment option for bullous keratopathy-induced therapy-resistant corneal erosions in dogs. Patient comfort was greatly improved, but corneal thickness decrease was not as long-lasting as reported for humans. The presently used protocols might need modification to fit the dog cornea.

Ocular manifestations of a metastatic adenocarcinoma in a horse

A 10-year-old German Warmblood gelding was referred to the Equine Department of the Vetsuisse Faculty, University of Zurich, Switzerland, for an iris mass OD, lethargy, intermittent fever, and coughing. Ophthalmic examination revealed a 7 × 9 mm raised, fleshy, whitish to pinkish, vascularized iris mass at the 2 o`clock position OD. Fundic examination showed multifocal round, brown to black, slightly raised lesions with indistinct margins and a surrounding hyperreflective zone OU. Physical examination revealed a temperature of 39.2 °C, sinus tachycardia, preputial and ventral edema, and an enlarged right mandibular lymph node. Results of a complete blood count and plasma biochemical profile showed mild anemia, leukocytosis, and thrombocytopenia. Severe splenopathy, moderate splenomegaly, and severe pulmonary pathology with nodules and large areas of consolidated lung parenchyma were observed on abdominal ultrasound and thoracic radiographs, respectively. Fine needle aspirates of the enlarged mandibular lymph node showed malignant epithelial neoplastic cells. The horse was euthanized because of the poor prognosis and subsequently underwent postmortem examination. Macroscopic necropsy and histopathology revealed an adenocarcinoma of suspected pulmonary origin with involvement of eyes, heart, liver, kidneys, spleen, diaphragm, skeletal muscles, mandibular, pulmonary, and internal iliac lymph nodes. Metastatic adenocarcinoma should be considered as a differential diagnosis in horses with iris masses, multifocal chorioretinal infiltrates, and clinical signs that conform to a paraneoplastic syndrome.

Protective coatings for intraocular wirelessly controlled microrobots for implantation: Corrosion, cell culture, and in vivo animal tests.

Diseases in the ocular posterior segment are a leading cause of blindness. The surgical skills required to treat them are at the limits of human manipulation ability, and involve the risk of permanent retinal damage. Instrument tethering and design limit accessibility within the eye. Wireless microrobots suturelessly injected into the posterior segment, steered using magnetic manipulation are proposed for procedures involving implantation. Biocompatibility is a prerequisite for these procedures. This article investigates the use of polypyrrole- and gold-coated cobalt-nickel microrobots. While gold has been used in ocular implants, no ocular implantation involving polypyrrole is reported, despite its well-established biocompatibility properties. Coated and uncoated microrobots were investigated for their corrosion properties, and solutions that had contained coated and uncoated microrobots for one week were tested for cytotoxicity by monitoring NIH3T3 cell viability. None of the microrobots showed significant corrosion currents and corrosion potentials were as expected in relation to the intrinsic nobility of the materials. NIH3T3 cell viability was not affected by the release medium, in which coated/uncoated microrobots were stored. In vivo tests inside rabbit eyes were performed using coated microrobots. There were no significant inflammatory responses during the first week after injection. An inflammatory response detected after 2 weeks was likely due to a lack of longer-duration biocompatibility. The results provide valuable information for those who work on implant technology and biocompatibility. Coated microrobots have the potential to facilitate a new generation of surgical treatments, diagnostics and drug-delivery techniques, when implantation in the ocular posterior segment will be possible.

Comparison of ultrasonography and histologic examination for identification of ocular diseases of animals: 113 cases (2000–2010)

OBJECTIVE To compare ultrasonographic and histologic examination findings for eyes of animals with ocular diseases. DESIGN Retrospective case series. ANIMALS 116 eyes of 113 animals examined at 2 facilities. PROCEDURES Diseased eyes of animals were examined by means of ultrasonography, removed via enucleation or exenteration, then histologically examined. Ultrasonographic images and histopathologic slides were evaluated, and diseases of eyes were identified with each of those methods and allocated to various categories. For each disease category, agreement between results of ultrasonography and those of histologic examination was assessed via determination of κ statistic values. RESULTS Tests had good agreement for identification of iris or ciliary body neoplasia. Overall, intraocular neoplasia was not detected via ultrasonography for only 2 of 31 eyes with histologically detected neoplasia. Hemorrhagic or inflammatory changes were misinterpreted as neoplasia for 8 of 37 (22%) eyes. Tests had moderate to acceptable agreement for identification of retinal detachment. Retinal detachment was not detected by means of ultrasonography for 14 of 38 (37%) eyes with that diagnosis determined via histologic examination at one of the facilities (primarily in eyes with intraocular hemorrhage); however, retinal detachment was not identified via histologic examination for 6 of 38 (16%) eyes with that diagnosis determined via ultrasonography at the other facility. CONCLUSIONS AND CLINICAL RELEVANCE Agreement between tests evaluated in this study was clinically satisfactory for identification of intraocular neoplasia. Typically, diseases were misdiagnosed via ultrasonography for eyes with poor image contrast. Because determination of ultrasonographic diagnoses of retinal detachment and intraocular neoplasm may be of prognostic importance, performance of additional ultrasonographic techniques may be indicated.

Orbito-nasal cyst in a young European short-haired cat

PURPOSE To describe a case of an orbito-nasal cyst in a cat. PROCEDURE An 18-month-old male European short-haired cat was presented to the Ophthalmology service of the Vetsuisse Faculty, University of Zurich for a subcutaneous swelling in the medial canthal region of the right eye (OD). Ophthalmologic, ultrasound and CT examinations, and fine needle aspiration were performed. After lesion excision, the removed tissue was submitted for histopathology. CT examination was repeated 5 months after removal of the cyst. RESULTS Ophthalmologic examination revealed a large fluctuant swelling inferonasal to OD. Despite patent lacrimal puncta, only the first few mm of the lacrimal canaliculi could be cannulated. A normal globe with moderate enophthalmos was present. Ultrasound examination showed a well-defined lobulated cyst-like structure in the right orbit, inferonasal and anterior to the eye. CT examination revealed extension of this lesion through the medial orbital wall into the right nasal cavity. Fine needle aspiration confirmed the cystic nature of the lesion. An orbito-nasal cyst was diagnosed. The orbital part of the cyst was dissected from the surrounding tissue and excised from the periosteum in the medial orbital wall defect. Part of the maxillary bone was removed to allow removal of the cyst from the nasal cavity. Histologically, the cyst wall consisted of a single to multilayered, mostly cuboidal epithelium and surrounding connective tissue. Follow-up revealed a good functional result and no recurrence 7 months after cyst removal. CONCLUSIONS Similar orbito-nasal cystic structures were reported in dogs but not in cats.

Sub-Tenon's injection in equine cadaver eyes: MRI visualization of anesthetic fluid distribution and comparison of two different volumes.

OBJECTIVE To compare the localization and distribution of two different anesthetic fluid volumes around equine cadaver eyes to determine an appropriate volume for a single sub-Tenons injection in horses. PROCEDURE A single sub-Tenons injection of 2% lidocaine was performed in 10 equine cadaver heads (20 eyes) using two different volumes (7 mL on one side and 10 mL on the opposite side). The posterior circular distribution of the anesthetic was quantified in sagittal, dorsal, and transverse MRI (T2W-TSE) sequences and evaluated independently by three board-certified radiologists. The distribution of the two fluid volumes was compared via a paired Students t-test. The interobserver reliability was evaluated via a Kruskal-Wallis test. RESULTS Extension of the injection fluid was observed along the dorsal and temporal quadrants of the globe within the subconjunctival space, the anterior and posterior sub-Tenons space, and into the muscle sheaths along the extraocular muscles. Accumulation of anesthetic fluid directly surrounding the optic nerve was detected in three of 20 cadaver eyes. Circular distribution of the 7 and 10 mL anesthetic volumes was not significantly different (P = 0.849). More retrograde leakage of the anesthetic was observed using the 10 mL volume. Evaluation of interobserver reliability revealed no significant differences between observers (P = 0.21-0.92). CONCLUSIONS Sub-Tenons anesthesia can have potential as an alternative to retrobulbar anesthesia for ophthalmic surgeries in equines. A 7- to 10-mL injection volume should be appropriate based on the results of this study. The distribution of the anesthetic solution in live tissues, the clinical effects, and the potential for complications will have to be evaluated in vivo.