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141 Cards in this Set
- Front
- Back
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Congenitally small, functional eye
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Microphthalmia
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Breeds with higher incidence of microphthalmia
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Appaloosas, thoroughbreds, Percherons
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Crossed eyes
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Esotropia
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Other ocular abnormalities associated with microphthalmia
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Strabismus, dermoids, microcornea, scleral colobomas, PPM's, cataracts, luxated lenses, detached retinas, optic nerve coloboma
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CS associated with periocular cellulitis
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Chemosis, exophthalmia, inability to close eye
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Usual cause of orbital cellulitis in the horse
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Trauma
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Treatment for orbital cellulitis
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Topical and systemic antibiotics, NSAIDS, drainage of abscess
May do tarsorraphy to protect eye NFZ pressure wrap |
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Negative Px indicators with orbital cellulitis
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Lens luxation
Retinal detachment |
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Possible complications of periorbital fracture
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Eyelid akinesia and/or lagophthalmos
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How common is orbital neoplasia in the horse?
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Uncommon
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CS of orbital neoplasia in the horse
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Slowly progressive nonpainful exophthalmia, 3rd eyelid protrusion, strabismus, and/or vision loss
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Breed in which anterior segment dysgenesis most commonly seen
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Rock Mountain Horse
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CS of anterior segment dysgenesis
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Cysts of iris, ciliary body, peripheral retina
Macropalpebral fissures, ketatoglubus with high myopia, malformed irides and miosis, cataracts, retinal dysplasia/detachment |
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Removal of eye only, leaving lids, third eyelid intact
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Enucleation
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Removal of globe, cojunctiva, third eyelid, all orbital tissue.
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Exteneration
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There is a knot of pigmented, haired tissue at the medial canthus. IS this a normal structure or an abnormality?
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Normal--> Lacrimal caruncle
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Entropion occurs congenitally in which two horse breeds?
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QH and TB
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Tx for entropion
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Manually rolling out lids frequently and lubricating
Palpebral nerve block and lubrication Temporary eversion sutures to roll out lid margins Hotz-Celsus proceedure of lower lid |
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Medical therapy for eyelid laceration
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Gently cleanse site, evaluate globe, protect globe until laceration may be repaired
Topical and systemic abx, systemic NSAIDs, tetanus prophylaxis Furacin wraps |
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Nerve block causing eyelid akinesia
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Paplebral branch CN 7
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4 sensory ocular nerve blocks
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Supraorbital
Infratrochlear Zygomatic Lacrimal |
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Layers of closure in eyelid laceration repair
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2-3
Close tarsal plate Close subcuticular tissue and skin |
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Suture type best suited to closing the tarsal plate
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Horizontal mattress
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Repeated sunburn of the eyelids predisposes horses to this cancer
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Squamous cell carcinoma
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Tx for ocular habronemiasis
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Ivermectin systemically
Intralesional steroids NSAIDs |
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Most common eyelid neoplasia in the older, dilute color horse
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Squamous cell carcinoma
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Dx of eyelid SCC is made on the basis of...
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Cytology of scrapings and/or histopathologic evaluation of biopsy
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Tx of SCC on the eyelid
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Excision followed by liquid nitrogen cryosurgery or radiofrequency hyperthermia
Cisplatin injections 5-fluorouracil injections Radiation straws Photosensitization therapy |
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Px for eyelid SCC
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Guarded, high chance recurrence
Metastasis more likely if on medial canthus, third eyelid and lid than if on the globe |
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Eyelid neoplasia mostly seen in younger horses
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Sarcoid
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This eyelid neoplasia appears as warty, flat or raised lesions, or as solid masses within the eyelid stroma.
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Sarcoid
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Is SCC or a sarcoid more aggressive on the eyelid of the horse?
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SCC
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Tx for eyelid sarcoid
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5-FU injections
Implantation of cisplatin beads Debulkment and AGGRESSIVE radiofrequency hyperthermia Liquid nitrogen cryotherapy Repeated injections BCG (3-6) |
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How does BCG treat sarcoids?
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Causes body's immune system to attack the tumor, and mass sloughs off.
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In which eyelid neoplasia is surgical excision alone usually curative?
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Melanoma
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Clinical signs of congenital atresia of the nasolacrimal duct
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Epiphora
Dacryocystitis with purulent discharge at 4-8 months if imperforate nasal punctum |
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Tx for imperforate nasolacrimal punctae
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Opening inferior punctae and cannulating opening for 3 weeks
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Is occulsion of the nasolacrimal ducts usually painful?
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No
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Usual cause of obstruction of the nasolacrimal duct
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Foreign bodies
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Tx for occlusion of nasolacrimal duct
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Flushing from nose to eye
Antibiiotic/steroid drops for infection and inflammation |
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Narrowest point of the nasolacrimal duct, where scarring may occur
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Bony canal in maxillary bone
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4 causes of protrusion of 3rd eyelid
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Pain
Loss of orbital contents Tetanus Horner's syndrome |
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Ocular mass seen in older color dilute horses
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Squamous cell carcinoma
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Rare tumor of eye in the horse, appears like "cherry eye" in the dog. Nonpainful, slowly progressive, unilateral
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Adenocarcinoma
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Px for ocular adenocarcinoma in horse
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Rapid spread to local lymphatics--> Death
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Px of ocular lymphoma
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Poor
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Tx of ocular lymphoma
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Clean excision of tumor and third eyelid
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Cause of prolapsed orbital fat
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Tear in orbital septum with herniation of fat into the third eyelid stroma
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How is allergic conjunctivitis diagnosed?
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Ruling out other diseases first like corneal disease or uveitis
Conjunctival scrapings (lymphocytes +/- eosinophils) Response to therapy with topical/systemic steroids and systemic antihistamines and removal of inciting causes) |
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How frequent is allergic conjucntivitis in the horse?
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RARE
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Site at which ocular SCC first appears
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Lateral limbus
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Which form of SCC is most likely to metastasize: Eyelid/third eyelid or globe?
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Eyelid and third eyelid
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Tx for ocular SCC
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Debulkment and cryotherapy or radiofrequency hyperthermia
May try Beta irradiation with Sr-90. |
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How aggressive is ocular angiosarcoma of the conjunctive?
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Malignant with high incidence of regional metastasis and dissemination
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Causes of ulcerative keratitis
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Trauma
Foreign body Exposure/ Paralytic keratitis EHV-2 KCS (rarely) |
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Main indicator of chronicity with a corneal ulcer
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Vascularization on the cornea
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A circumferential "moat" surrounding a corneal lesion is characteristic for...
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Fungal keratitis
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Why are Descemetoceles usually clear?
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Lack of corneal stroma
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Most useful test to rule out corneal ulcer if unsure of its presence
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Fluoroscein stain
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Most common secondary bacterial invader with corneal lesions
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Streptococcus (resistant)
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3 types of complicated corneal ulcers
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Secondary infection
Stromal degredation Iridiocyclitis |
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3 goals of therapy with corneal ulcers
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Control corneal infection
Inhibit corneal proteolysis Increase patient comfort |
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Medical management for corneal ulceration includes
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Topical antibacterials like triple antibiotic
Topical antifungals (miconazole 1%) Systemic antifungals Solutions delivered via subpalpebral lavage system Topical atropine (cycloplegic) Systemic NSAIDs Anti-proteases |
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Types of anti-proteolytic treatments for ulcerative keratitis
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Topical utologous serum
Topical N-acetylcysteine Tetracyclines |
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Non-complicated corneal ulcers tend to head within...
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7-10 days
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When would keratectomy and conjunctival flap be used for treatment of corneal ulcer?
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Descemetocele
Melting ulcer Secondary infection |
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Term for "non-healing" superficial ulcers
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Chronic superficial erosion
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Treatment for chronic superficial erosion
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Topical abx
Debridement Ketatotomy Keratectomy |
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Procedure in which the cornea is surgically "scratched"
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Keratotomy
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CS of corneal perforation in the horse
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Iris prolapse with fibrin
Corneal edema Hyphema/hypopyon |
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When the globe has a "blowout," typical site of rupture is at this region.
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Limbus
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Pre-operative management for corneal perforation
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Topical and systemic abx
Topical anti-fungals Topical atropine Oral NSAIDs |
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Negative Px indicators for corneal perforation
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Blunt trauma
Ulcerative eitology Endophthalmitis Severe hyphema Lens rupture Chronic rupture |
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CS of corneal abscess
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Yellow-white stromal opacity
Severe ocular discomfort |
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Management for corneal abscess
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Must vascularize to resolve
Surgical excision and conjunctival flap Keratoplasty |
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Three topical medications capable of penetrating an intact corneal epithelium
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Chloramphenicol
Fluoroquinolones Miconazole |
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Hepres subtype that may cause EHV keratitis
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EHV2
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CS of EHV keratitis
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Multiple superficial punctate opacities
Ulceration variable |
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Tx for EHV keratitis
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Topical antivirals
but tend to be self limiting and resolve on own |
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CS of eosinophilic keratoconjunctivitis
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Ocular discomfort
Raised pink-whote necrotic corneal plaque Variable corneal ulceration |
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Cause of eosinophilic keratoconjunctivitis
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Unknown, possibly hypersensitivity
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Diagnosis of eosinophilic keratoconjunctivitis based on...
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Corneal cytology
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Treatment for eosinophilic keratoconjunctivitis
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Topical corticosteroids (caution though!)
Topical cyclosporine Keratectomy |
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Prognosis for eosinophilic keratoconjucntivitis
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Good
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Typical site for corneal SCC
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Lateral limbus, with corneal and conjunctival involvement
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Tx for corneal SCC
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Surgical excision
CO2 laser ablation Cryotherapy (adjunctive) Radiation therapy (adjunctive) Topical chemotherapy |
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Px of corneal SCC
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Usually good, noninvasive
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Causes of equine cataracts
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Congenital
Secondary to ERU Anterior segment dysgenesis Trauma |
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Describe progression of cataracts in foals
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Become nuclear as animal grows, compress toward center of lens
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Type of equine cataract that makes a reasonable surgical candidate
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Congenital cataracts with no other abnormalities
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Post-op outcome of cataract surgery in the foal
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Foal very far-sighted
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Causes of lens luxation in the horse
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Congenital (rare)
ERU Glaucoma |
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Tx for lens luxation
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Surgical removal: Intracapsular extraction
Only in congenital cases Low success rate |
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Complications of intracapsular lens extraction
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Uveitis, glaucoma, and retinal detachment
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CS of acute anterior uveitis
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Blepharospasm
Miosis Aqueous flare/hypopyon/hyphema |
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CS of chronic uveitis
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Blepharospasm
Miosis Aqueous flare/hypopyon/hyphema Cataract Retinal detachment Secondary glaucoma Phthisis bulbi |
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Bacterial causes of acute anterior uveitis
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Leptospira
Brucella Streptococcus Rhodococcus Borrelia burgdorferi |
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Viral causes of acute anterior uveitis
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Equine influenza, EVA, Parainfluenza type 3
EHV-1 and EHV-2 |
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Treatment for acute anterior uveitis
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Manage underlying condition
Systemic NSAIDs Topical corticosteroids (IFF non-ulcerated) Topical atropine |
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Major cause of blindness in the horse
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ERU
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Prevalence of ERU in the US
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8-25%
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Typical age at onset of ERU
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4-6 years
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CS of ERU
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Blepharospasm
Miosis Aqueous flare/hypopyon/hyphema Posterior uvea: Vitreal hazing, syneresis, and chorioretinitis Synechia, cataracts, retinal detachment, phthisis bulbi |
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Two forms of ERU and their CS
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Classic syndrome: Intermittent flare-ups
Chronic low-grade syndrome: Persistent low grade inflammation, with little-to-no overt CS |
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Possible mechanisms of ERU
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Organism/Ag incorporating into uvea after uveitis episode
Ag-Ab complex deposition T-lymphocytes persist in uveal tract and reactivate |
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Common initiating causes of ERU
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Immune-mediated hypersensitivity
Leptospirosis Onchocerca cervicalis |
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Pathogen long associated with ERU
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Leptospira interrogans
(Pomona and grippotyphosa m/c implicated) |
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Dx of ERU based on...
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Serum biochem and CBC
Serology for Leptospira, etc. Conjunctival biopsy for Onchocerca Ocular U/S to evaluate retina |
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Tx for ERU
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Systemic NSAIDs
Topical corticosteroids Topical atropine Abx Surgery: Supreachoroidal cyclosporine implant or virtectomy |
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Px of ERU
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Long term px for vision is poor
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Syndrome that may present as ciliary body cysts, inability to dilate pupil, goniosynechiae, macropalpebral fissure, macrocornea, cataract, and lens luxation
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Anterior segment dysgenesis
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Dark bodies connected to iris or ciliary body, may even be free floating
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Uveal cysts
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Most common form of uveal neoplasia in the horse
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Melanoma
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Breed of horse predisposed to ERU
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Appaloosa
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Technique for treating ERU that minimizes relapse
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Treat aggressively until symptoms controlled
Taper medications gradually |
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Systemic abx anecdotally of use in ERU cases
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Penicillin/Gentamicin
Doxycycline |
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Evoironmental modifications for addressing ERU
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Change pasture/stable
Change bedding type Decrease dust exposure |
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Normal equine IOP
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17-28 mmHg
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Most cases of equine glaucoma are secondary to...
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ERU
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CS of glaucoma in horses
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Vision loss
Corneal edema Haab's striae Dilated non-responsive pupil Lens subluxation Buphthalmos |
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How is glaucoma diagnosed?
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CS and documentation of elevated IOP
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Medical treatment for glaucoma
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Topicals: timolol maleate, CA inhibitors, miotics, atropine, corticosteroids
Systemic NSAIDs |
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Surgical tx for glaucoma
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Visual eyes: Laser photocoagulation for IOP control
Blind eyes: Enucleation/evisceration of globe |
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Px for equine glaucoma
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Poor for long-term vision
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True or false: Equine IOP is a fairly constant value in an individual horse
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False: Waxes and wanes dramatically
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Beta blocker drug that reduces aqueous humor production. Used to treat glaucoma
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Timolol
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Sx in which ciliary body epithelium is destroyed so that aqueous production is reduced
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Laser cyclophotocoagulation
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Type of retina in the horse
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Paurangiotic
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In which portion of the fundus is the equine optic nerve located?
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Non-tapetum
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End-on choroidal capillaries that appear as small black dots on the tapetum of the horse
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Stars of Winslow
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Normal day vision but impaired vision in dim light is called...
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Congenital Stationary Night Blindness
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Breed most commonly affected by congenital stationary night blindness
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Appaloosas
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Appears on the retina as paripapullary "butterfly" lesions, "buller hole" lesions, etc.
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Chorioretinitis
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Two possible causes of chorioretinitis.
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ERU
EHV |
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Yellow-brown mosaic of discoloration in tapetal retina and horizontal band of pigmentation in tapetal-non-tapetal junction. May be related to vitamin E deficiency
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Equine Motor Neuron Disease Retinopathy
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Px for traumatic optic retinopathy
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Grave for vision
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Slowly enlarging white mass protruding from optic disc into the vitreous of older horses. Usually asymptomatic and not affecting vision
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Proliferative optic neuropathy
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Swollen optic discs and peripapillary retinal edema/hemorrhage that causes bilateral acute blindness in older horses
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Exudative optic neuropathy
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Tx for exudative optic neuropathy
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None known
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Tx for congenital stationary night blindness
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None
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How does the retina appear in congenital stationary night blindness?
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Normal
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