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46 Cards in this Set

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What external aspects of the eye should be examined?
Ocular discharge - epiphora, inflammatory exudate, nasolacrimal reflux
Size of the globe - phthisis bulbi (shrunken), buphthalmia (enlarged)
Periorbital swelling, masses, alopecia, ulcerations or drooping eyelid, elevated or retracted eyelid; abnormal eyelid mobility, decreased sensation, laceration
3rd eyelid - prolapsed (due to mass or enophthalmus), masses (especially squamous cell carcinoma)
What tests should you do for vision response and reflex testing?
Menace response
Dazzle reflex
Palpebral refelx
Pupillary light reflex
Corneal reflex
What is tested with the menace response?
Crude estimation of vision (tests retina, CN II, visual cortex, CN VII)
Not a reflex!
What is tested with the dazzle reflex?
Abrupt bright light into eye usually causes blink (tests retina, CN II, CN VII, rostral colliculus, orbicularis oculi)
What is tested with the palpebral reflex?
Tests CN V, CN VII
What does the pupilary light reflex test?
Function of Retina
Optic nerve
Midbrain
Oculomotor nerve
Iris
Consensual PLR tests retina, CN II, midbrain, CN III
What does the corneal reflex test?
When the cornea is touched, the animal should blink, and the globe should retract.
Tests CN V, CN VII, CN VI
What nerves should be blocked for an equine eye exam?
Frontal nerve (sensory) - inject into supraorbital foramen
Palpebral nerve (motor) - inject along the lateral aspect of the highest portion of the zygomatic arch
What nerves should be blocked for a bovine eye exam?
Palpebral nerve - inject along the zygomatic arch
When would you use a retrobulbar block? What nerves does it block?
Used to facilitate ocular and orbital surgery.
Blocks CN II, III, VI, IV, and the maxillary and ophthalmic branches of CN V
What is the difference between transillumination and retroillumination?
Transillumination: examination of the anterior structures of the eye using a focal direct light source (ex. penlight)
Retroillumination: examination of the ocular structures that relies on reflextion of light from the fundus to illuminate these structures. Can be done through a direct ophthalmoscope or slit lamp.
What is direct ophthalmoscopy?
The lightsource's light path is the same as your own eye's "view path", meaning the light shines through any lens or objective that you look though. This results in opaque lesions that appear dark against a light background and transparent lesions that appear clear within a dark halo, as the light is reflected right back into your own eye.
You can use a direct ophthalmoscope for this.
Results in an upright, magnified image.
What is indirect ophthalmoscopy?
The lightsource's path is different from your own eye's "view path" meaning the light shines into the eye from an angle, and not through the lens/objectives you look through.
Lesions are observed against a darker background, as the light is not reflected back into your eye.
This improves detection of transparent lesions by taking advantage of differences in the lesion's refractive index and the surrounding structure's refractive index.
You need a lens and a light source or a slit-lamp.
The image is inverted and reversed.
What structures do you examine in the anterior aspect of the eye?
Conjunctiva
Cornea
Anterior chamber (aqueous flare, hyphema, hypopion)
Iris (size of corpora nigra, color of iris, anterior synechia)
Purkinje-Sanson reflexes
What drug do you use to dilate the pupil?
Tropicamide 1% - takes 10-20 minutes to take effect and lasts 4-6 hours
What structures do you examine in the posterior aspect of the eye?
Lens position, opacities
Vitreous clarity, contents
Fundus
Retina
Optic disk
What topical anesthetic is used for eye exams?
Proparacaine 0.5%
What is a tenometer used to measure?
A tenometer measures intraocular pressure.
Normal pressure is 16-22 mmHg
When is the best time to take a culture sample from the eye?
Culture should be performed prior to administration of any solution or ointment.
What is the normal range for a Shirmer tear test?
20-30 mm/60 seconds
When is the best time to do a corneal scraping for cytology?
After topical and local anesthesia have been performed.
What layers of the cornea does fluorescein stain bind to?
Binds to corneal stroma only
What is inversion/rolling of the eyelid called?
Entropion
What are some treatment options for entropion?
Inject the eyelid with procaine penicillin to inflate the lid until the foal "grows into it".
Horizontal or vertical mattress sutures to evert the eyelid.
Removal of a segment of skin from the eyelid.
True or false:
When repairing an eyelid laceration, it's good to remove any loose flaps of the lid that may be hard to suture back.
False! Never excise a hanging eyelid fragment!
How should eyelid lacerations be closed?
2 layer closure
Use 4-0 or 5-0 absorbable
Simple continuous pattern
Do not let knots or suture have contact with the cornea (don't penetrate the conjuntiva!)
Start at the eyelid margin for best apposition
Use 3-0 or 4-0 absorbable to close the skin
Clinical signs of corneal injury?
Cloudy cornea (edema)
Vascularization
Redness
Cellular deposits
Epiphora
Drooping eyelid
Blepharospasm
Ocular discarge
What diagnostics should be done on a corneal ulcer?
Fluorescein stain
Determine the extent of the problem (stromal melting, uveitis, foreign body, stromal abscess, descemetocele)
Culture and sensitivity
Corneal scraping and cytology - to evaluate for bacteria, fungi, inflammatory cells
What is the treatment for corneal ulceration?
Abx oinment
+/- Antifungal ointment
Cyclopegic (Atropine)
Topical NSAIDS
Anticollagenase ointment therapy (autologous serum)
Systemic NSAIDS
What are some surgical treatment options for corneal ulceration?
Tarsorrhaphy - not commonly used by itself
Conjunctival graft
Third eyelid flap - used more in cattle
Suturing of corneal lacerations - if wound extends to Descemet's membrane suturing is recommended (use 6-0 to 9-0 absorbable)
What are some bad prognostic indicators for full thickness corneal lacerations?
Laceration > 15mm
Involvement of the limbus
Presence of keratomalacia or hyphema.
What is the most common ocular tumor of horses?
Squamous cell carcinoma
What is the most common peri-occular and skin tumor of horses?
Equine sarcoid
What are possible treatments for equine sarcoid?
Surgical debulking/exision +/-:
Cryotherapy
Cisplatin injection
Topical chemotherapy
Radiotherapy
What is the most common ocular cancer in cattle?
Squamous cell carcinoma
What procedure involves removal of the globe, conjuntiva, and 3rd eyelid?
Enucleation
What are indications for enucleation?
Severe corneal infection and endophthalmitis
Corneal or adnexal neoplasia
Orbital neoplasia
Painful and blind eye
What is the most common peri-occular and skin tumor of horses?
Equine sarcoid
What are possible treatments for equine sarcoid?
Surgical debulking/exision +/-:
Cryotherapy
Cisplatin injection
Topical chemotherapy
Radiotherapy
What is the most common ocular cancer in cattle?
Squamous cell carcinoma
What procedure involves removal of the globe, conjuntiva, and 3rd eyelid?
Enucleation
What are indications for enucleation?
Severe corneal infection and endophthalmitis
Corneal or adnexal neoplasia
Orbital neoplasia
Painful and blind eye
What procedure includes removal of all orbital contents (periorbita and globe)?
Exenteration
What are indications for exenteration?
Large, malignant tumors of the orbit
What procedure includes removal of the iris, lens, ciliary body, choroids, vitreous, and retina?
Evisceration
What is tarsorraphy?
Suturing the eyelid closed to allow the eye to heal.