Treatment of corneal ulceration and bullous keratopathy using a nictitating membrane flap in two horses

Objective

The aim of this study was to describe placement of a nictitating membrane flap as a treatment for corneal ulceration and bullous keratopathy in two horses.

Animals Studied

A 13-year-old American Saddlebred mare presented for severe corneal edema, superficial stromal ulceration, and a central bulla of the left eye. A 4-year-old Trakhener stallion also presented with a large axial bulla of the left eye with concurrent severe corneal edema and a deep stromal ulcer.

Procedure

A complete ophthalmic examination was performed. Samples were obtained for corneal cytology, and both horses were started on aggressive medical therapy. Both underwent general anesthesia for placement of a nictitating membrane flap and a subpalpebral lavage system (SPLS).

Results

Corneal cytology for each horse revealed a mixed bacterial population. Moderate Pseudomonas aeruginosa was cultured from the mare, while Aspergillus species and a few Enterococcus gallinarum were cultured from the stallion. The bullae in both horses resolved at 3 and 4 weeks and vision returned in the affected eye 4.5 and 3 months postoperatively at the last follow-up, respectively.

Conclusion

Aggressive medical management with concurrent placement of a nictitating membrane flap is effective to treat bullous keratopathy in two horses. The described treatments could be used to treat horses that develop severe or progressive bullous corneal lesions.     

Nonulcerative bullous keratitis associated with Pseudomonas alcaligenes infection in a Thoroughbred mare

A 5‐year‐old Thoroughbred mare presented with an intermittently mildly painful right eye with a nonulcerative corneal opacity of several weeks' duration that had improved with topical steroids but recurred when steroids were withdrawn. Ophthalmic examination demonstrated a focal region of moderate corneal oedema and midstromal corneal infiltrate centrally but no other significant ocular abnormalities, and suggested a diagnosis of immune‐mediated keratitis. Empirical courses of both topical and systemic anti‐inflammatory drugs, both nonsteroidal and steroidal, led to initial improvement but bullous keratopathy developed when corneal oedema became profound. Due to the rapidly progressive nature of the bullous keratopathy combined with poor response to medical therapy, a keratectomy and conjunctival graft were performed under general anaesthesia. Intraoperative corneal culture of the keratectomy site grew Pseudomonas alcaligenes, a common soil and water contaminant. Histopathology of the keratectomy specimen revealed neutrophilic inflammation. Keratectomy and conjunctival graft led to resolution of ocular pain and inflammation, with an acceptable cosmetic and visual outcome. This report describes an unusual case of a nonulcerative Pseudomonas keratitis that responded well to surgical therapy, and underscores the complicated nature of nonulcerative keratitis in horses.     

Acute corneal hydrops of presumed traumatic origin: An uncontrolled case series (three horses)

This case series describes acute corneal hydrops in three young horses. Due to similarities in the clinical appearance and progression of the disease with that which is reported in humans and cats with acute corneal hydrops, traumatic Descemet’s membrane rupture was suspected to be the underlying aetiology in these equine cases. The horses presented with acute severe corneal oedema with intrastromal bullae formation and anterior bulging of the corneal contour. Focal posterior corneal changes were also seen in two of three cases. Mild anterior uveitis was also present. Other causes of corneal oedema (e.g. glaucoma) were ruled out based on presentation and clinical examination. Treatment approaches were medical and included various combinations of prophylactic topical antimicrobial therapy in case of secondary corneal ulceration, anti-inflammatory therapy for uveitis, targeted oedema therapy with topical hypertonic saline and corneal cross-linking, and placement of a temporary partial tarsorrhaphy for corneal tamponade. The outcome was excellent in all cases, with rapid resolution of the ocular changes. Acute corneal hydrops of presumed traumatic Descemet’s membrane rupture origin should be considered in cases of young horses presenting with acute corneal oedema. However, further studies are warranted to better characterise the disease and to try to confirm the suspected aetiology.     

Ulcerative fungal keratitis in a Brown Swiss cow

An 11‐year‐old Brown Swiss cow was referred to the Farm Animal Department of the Veterinary Teaching Hospital in Zurich, Switzerland, because of lateral recumbency due to puerperal hemolytic anemia. The animal had developed enophthalmos due to dehydration at the time of presentation. Two days after hospitalization, the cow showed blepharospasm and epiphora of the right eye. Ophthalmic examination of the right eye revealed a fluorescein‐positive, paraxial, superficial corneal ulcer with focal edema, and mild superficial neovascularization. White corneal stromal infiltrates were seen at the edges of the ulcer bed. After initial topical treatment with an antibiotic ointment (Neomycin 3.5 mg/g, Bacitracin 250 IU/g) three times a day, an increase in corneal infiltrates was noted on re‐examination 2 days later. Several fluorescein‐negative, punctate, stromal, white opacities were seen dorsal to the ulcer. Cytology demonstrated the presence of fungal hyphae. Topical treatment with 2% miconazole ointment and 0.36% K‐EDTA eye drops six times daily and four times daily, respectively, from the second day and continued antibiotics three times daily resolved the clinical symptoms within 6 days. Fungal culture identified the fungal organism as Eurotium amstelodami.     

Normal corneal thickness measurements in pigmented rabbits using spectral‐domain anterior segment optical coherence tomography

Objective  To document the thickness of the central cornea in pigmented rabbits using spectral‐domain anterior segment optical coherence tomography (AS‐OCT). Animals studied  Seventeen pigmented rabbits (6 male, 11 female, both eyes) were involved in this study. Procedures  Thirty‐four eyes from healthy pigmented rabbits underwent a complete ophthalmologic examination, including AS‐OCT. Eight radial scans, 6 mm in length and centered on the cornea, were obtained using the AS‐OCT. Corneal thickness was automatically calculated using pachymetry software. Measurements were displayed as the mean and standard deviation for each of the 17 regions defined by the software. The regions were the center (1 mm radius, area a), the inner ring (2.5 mm radius, area b), the outer ring (3 mm radius, area c), and the eight radial scan lines in eight directions (Superior (1), SN (2), Nasal (3), IN (4), Inferior (5), IT (6), Temporal (7), ST (8)) with an angle of 45° between each consecutive scan line (a, b 1–8, c 1–8). Results  There was no statistically significance difference in corneal thickness between gender, eye, and the eight directions (P = 0.804, P > 0.05, P > 0.05). There was a statistical difference between the thickness in areas a, b, and c (P < 0.05). The corneal thickness increased gradually from the center to the periphery of the 6 mm measured. The center corneal thickness was 387 ± 19.8 μm for OD and 384 ± 20.2 μm for OS. The corneal thicknesses of the thinnest point of the right eyes (OD) and the left eyes (OS) were 376 ± 20.2 and 370 ± 16.8 μm, respectively. There was positive correlation between the thinnest point and area a in both the right eyes (r = 0.892, P < 0.001) and the left eyes (r = 0.832, P < 0.001). Conclusions  This is the first documentation of the rabbit corneal thickness in vivo using the spectral‐domain AS‐OCT. Pigmented rabbit corneas were almost 150 μm thinner than human corneal values. Gender and eye were not associated with any statistical differences in central corneal thickness in this study.     

Coccidioides posadasii keratouveitis in a llama (Lama glama)

A 7-year-old male llama was examined for a 3-month history of weight loss, and unilateral keratouveitis. Clinical examination revealed nonulcerative corneal stromal abscessation, corneal vascularization, corneal edema, miosis, posterior synechia, cataract, and fibrin in the anterior chamber of the right eye. The left eye was normal. Histopathology of the right eye following enucleation revealed pyogranulomatous keratouveitis with intralesional fungal spherules consistent with Coccidioides spp. PCR amplification with DNA sequencing confirmed Coccidioides posadasii infection. To the authors' knowledge, this is the first reported case of ocular coccidioidomycosis in a llama.     

Amniotic membrane transplantation for the reconstruction of the ocular surface in three cases

This paper describes the use of amniotic membrane in the reconstructive surgical repair of generalized keratomalacia, ankyloblepharon, and after fibrous histiocytoma removal in two dogs and a cat. Case 1 was an 11-year-old female Yorkshire terrier with severe bullous keratomalacia in the left eye (OS). A frozen canine amniotic membrane graft and a third eyelid flap were applied. At day 80 postoperatively, only a mild scar and corneal vascularization were present. Case 2 was a 4-year-old female Siamese cat with symblepharon of both eyes after rhinotracheitis. Resection of the conjunctiva and frozen canine amniotic membrane transplant were performed. One month later, there was a little corneal scarring and corneal vascularization. Case 3 was a 6-year-old female terrier with a scleral and corneal mass at the 11-12 o'clock position (OS). Resection of the mass and amniotic membrane transplantation were performed. The mass was a fibrous histiocytoma localized to the sclera and cornea. This eye healed with mild conjunctivalization and no pigmentation. Amniotic membrane transplantation can be used as a method of reconstruction of the ocular surface with good repair of the cornea and minimal scarring in small animals.     

Bilateral parotid duct transposition for keratoconjunctivitis sicca in a Connemara stallion

A 7‐year‐old Connemara stallion was presented with a 4 month history of blepharospasm, recurrent corneal ulcerations, mucopurulent ocular discharge, and keratoconjunctivitis sicca (KCS) in both eyes unresponsive to medical therapy. Ophthalmic examination revealed lackluster corneas, axial corneal scarring and pigmentation with associated neovascularization, and absolute KCS in both eyes. Computed tomography scan and endoscopic evaluation of the upper airway and guttural pouches revealed no structural abnormalities to indicate neurogenic KCS. The stallion was diagnosed with immune‐mediated dacryoadenitis as all other causes of KCS were excluded. Parotid duct transposition (PDT) was performed in the right eye followed by PDT in the left eye 4 weeks later. The right PDT was functional 2 years post‐operatively with significant improvement in ocular comfort and reduced corneal fibrosis and neovascularization. The left PDT developed a salivary‐cutaneous fistula over the left masseter muscle post‐operatively due to avascular necrosis of the distal parotid duct (PD). Surgical reconstruction of the PDT using an expanded‐polytetrafluoroethylene (e‐PTFE) tube graft, an e‐PTFE tube graft to autogenous caudal auricular vein graft, and an autogenous saphenous vein graft were all unsuccessful. Tear production in the left eye improved at 1 year post‐surgery as a result of long term lacrostimulant therapy, and a permanent PD‐cutaneous fistula was performed on the left PD at the level of the ventral mandible. Bilateral PDT in the horse is effective in resolving clinical signs associated with KCS; however, morbidity associated with avascular necrosis of the transposed PD may be significant and can result in surgical failure.     

Amniotic membrane transplantation for the treatment of feline corneal sequestrum: pilot study

Objectives To describe and evaluate the use of equine amniotic membrane trans‐plantation after lamellar keratectomy for the treatment of corneal sequestrum in cats. Methods Six cats (seven eyes) of various breed and ages with corneal sequestra were treated surgically with lamellar keratectomy and amniotic membrane transplantation. All the sequestra and a small piece of the amniotic membranes used for each surgery were submitted for histopathologic examination. Results Five of the seven eyes showed minimal level of scarring in the cornea and good transparency. No recurrences of the sequestra have been noted during the follow‐up period (3–9 months). One eye had necrosis of the amniotic membrane 2 weeks after the surgery. The sequestrum of this eye showed a high level of bacterial contamination on histopathology. Three months later the same cat developed a descemetocele in the area where the necrotic amniotic membrane was rejected. A second eye developed a perforation under the amniotic membrane two weeks after the surgery. The sequestrum of this eye was deep and without vascularization. Conclusion Amniotic membrane transplantation after lamellar keratectomy was a valid procedure for surgical treatment of corneal sequestrum in cats. The procedure resulted in excellent cosmesis and functional vision in five of seven eyes; although case selection is important, particularly to exclude the very deep and non‐vascularized sequestra.     

Bilateral third eyelid ectopic cilia in an adult horse

A 15‐year‐old Cob mare presented with a 4‐month history of chronic epiphora and intermittent blepharospasm in the right eye. On ophthalmic examination, two translucent aberrant hairs were identified at the third eyelid margin corresponding to an area of corneal fibrosis and neovascularization. Partial excision of the third eyelid was performed, and histopathology confirmed ectopic hair follicles. Two weeks later, clinical signs recurred in the same eye. Examination revealed another pair of aberrant hairs on the bulbar surface of the third eyelid near its leading edge. This portion of the third eyelid was also excised, and histopathology confirmed two additional ectopic hair follicles. Eight months later, the horse developed similar clinical signs in the left eye. Ophthalmic examination showed a single aberrant translucent hair at the third eyelid margin associated with focal fibrosis and neovascularization of the ventromedial cornea. Partial excision of the third eyelid was performed, and histopathology confirmed an ectopic hair follicle within the third eyelid conjunctiva. Excision was curative at 4 years postoperatively with no further recurrence in either eye.     

Septic lens implantation syndrome in a cat

A 13-year-old female spayed domestic shorthair cat was presented initially for a change in the appearance of the left eye. On initial examination, a small penetrating wound was suspected as the cause for a corneal scar, an anterior cortical incipient cataract and mild iritis. The cat was not re-presented until 1 year later at which time ocular pain was marked. Severe anterior uveitis and glaucoma were diagnosed and the eye enucleated. Histopathology documented intralenticular coccoid bacteria and septic lens implantation syndrome.     

Acute bullous keratopathy in a domestic shorthair

A 14-year-old cat was presented for corneal rupture of the right eye and bulla formation of the left cornea. It was diagnosed with acute bullous keratopathy, based on clinical and histopathologic examination. This is a rare condition of unknown origin in cats; it was treated successfully with bilateral conjunctival pedicle grafts.     

Congenital ocular anomalies and ventricular septal defect in a dromedary camel (Camelus dromedarius).

A 5-wk-old female dromedary camel (Camelus dromedarius) was clinically diagnosed with bilateral corneal dermoids, incomplete congenital cataracts, a left persistent hyaloid artery (PHA), and a ventricular septal defect (VSD). The corneal dermoids were removed by lamellar keratectomy, and vision improved in the left eye. Thirteen months after dermoid surgery, the calf was presented for enlargement of the right eye. Glaucoma was confirmed in the right eye, and corneal fibrosis and cataract were noted in the left eye. Persistence of the VSD was confirmed by cardiac ultrasonography. The calf was euthanized, and necropsy findings confirmed VSD. Histopathologic examination revealed bilateral corneal thinning and fibrosis, cataracts with retrolental fibroplasia, and retinal dysplasia. Additional changes in the right globe were anterior segment dysgenesis, ruptured lens capsule, chronic phacoclastic uveitis, and retinal separation. The PHA was confirmed in the left eye.     

Suspected uveal metastasis of a nail bed melanoma in a dog

A 13-year-old Golden Retriever was referred for evaluation of generalized corneal edema, dyscoria, and suspected glaucoma affecting the right eye. The dog exhibited no signs of systemic illness, but had a history of a melanoma of the nail bed of the first digit of the right hind limb, excised 1 year previously. Ophthalmologic examination revealed diffuse corneal edema, mild anterior uveitis, glaucoma and a mass within the right iris. Enucleation was performed and histopathologic evaluation of the globe revealed the iris to be infiltrated with an anaplastic melanoma, suspected to represent a metastasis of the original nail bed tumor.     

Primary bilateral corneal nerve sheath neoplasm in a dog

A 15‐year‐old, neutered male, Shih Tzu cross developed progressive corneal stromal thickening and vascularization of the right eye, and 5 months later, of the left eye. Both eyes became blind due to extensive corneal opacification and were enucleated. Light microscopic examination revealed a diffuse corneal infiltrate of neoplastic mesenchymal cells, and immunohistochemistry revealed diffuse cytoplasmic vimentin immunoreactivity and variable cytoplasmic and nuclear immunoreactivity for S100 in the neoplastic cells. Transmission electron microscopy revealed desmosomes between contiguous cells, thread‐like cytoplasmic processes coated with basement membrane, extracellular bundles of collagen, and axonal degeneration consistent with features of a nerve sheath neoplasm. This is the first report of primary, bilateral corneal nerve sheath sarcoma in a canine.     

Management of bilateral uveitis in a Toxoplasma gondii-seropositive cat with histopathologic evidence of fungal panuveitis

A 5-year-old, neutered male Domestic Short-haired cat was referred with a 5-month history of anterior uveitis and cataract in the right eye. Clinical examination confirmed anterior uveitis and immature cataract in the right eye and chorioretinitis in the left eye. Ocular ultrasound showed a retinal detachment in the right eye. Diagnostic testing revealed elevated serum titers for Toxoplasma gondii. Anterior uveitis in the right eye and chorioretinitis in the left eye progressed, resulting in blindness despite a 21-day course of clindamycin and aggressive topical medical management of uveitis. The right eye was enucleated and histopathologic evaluation of the globe revealed panuveitis and multiple organisms morphologically consistent with Histoplasma capsulatum. Systemic treatment with itraconazole was initiated. Vision returned after 3 months of treatment and complete resolution of the retinal hemorrhages with formation of a flat chorioretinal scar was noted after 6 months of therapy. Itraconazole was discontinued 7 months after starting therapy, at which time the funduscopic appearance of the chorioretinal scar had remained static for 1 month. The cat has remained visual without evidence of disease progression for 6 months following discontinuation of itraconazole.     

Intracapsular lens removal in a Przewalski's wild horse (Equus caballus przewalskii).

A 11.5-yr-old female Przewalski's wild horse (Equus caballus przewalskii) presented for unilateral blepharitis and drainage from the left eye. The left cornea was not ulcerated, and intraocular evaluation was hampered by severe corneal edema. The left eye appeared to respond positively to treatment with anti-inflammatories and a topical mydriatic agent. During the ensuing 2 yr, there were minor episodes of epiphora from the left eye. The discharge then increased, and a luxated lens was noted during an examination by a veterinary ophthalmologist as part of the preshipment examination. Initially, the lens was located in the anterior compartment but was in the vitreal compartment at the time of surgery, complicating the intracapsular extraction. After successful removal of the lens, the horse was transferred to a new institution without incident, where it appears to have adapted well to its probable loss of vision in the left eye. No further episodes of uveitis, corneal edema, or epiphora have been reported, and the horse has successfully foaled at the new institution.     

Anterior lens capsule disruption and suspected malignant glaucoma in a dog

A Boston Terrier puppy presented with a full-thickness peripheral corneal defect, iris prolapse and anterior lens capsule tear in the left eye (OS). Phacofragmentation and primary repair of the corneal laceration was performed. At surgery, subluxation of the lens was also apparent. One day postoperative, there was severe corneal edema, diffuse hyphema, an intraocular pressure (IOP) of 65 mmHg and a small amount of vitreous that protruded from the corneal incision OS. Malignant glaucoma or pupillary block glaucoma were suspected. Intravenous mannitol was administered preoperatively and had no effect. An anterior vitrectomy was performed on the vitreous within the anterior chamber and pupil. One day postoperative the IOP was 16 mmHg in the right eye (OD) and 20 mmHg OS. Postoperative iridocyclitis was managed medically, and additional elevations in IOP were not recorded. Resolution of the elevated IOP following anterior vitrectomy was supportive of pupillary block or malignant glaucoma. Vision returned 3 weeks after the initial surgery. Two years after the initial injury, the eye is visual and comfortable with infrequent topical anti-inflammatory therapy.     

Retrobulbar pseudotumor of the orbit in a cat

Idiopathic nonspecific inflammatory disease of the orbit (orbital pseudotumor) was diagnosed detected in a cat. The cat had progressive lagophthalmia, keratitis, and decreased motion of the right eye. Four months later, the left eye was affected in a similar manner. Response to antibiotics and immunosuppressive agents was not detected. Computed tomography of the brain and orbits revealed bilateral thickening of the sclera and episcleral tissues. Bilateral exenteration of the eyes was required because of worsening clinical signs or corneal perforation. Histologic examination revealed proliferation of spindle cells and fibrovascular tissue within and adjacent to the sclera.