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46 Cards in this Set
- Front
- Back
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What external aspects of the eye should be examined?
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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) |
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What tests should you do for vision response and reflex testing?
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Menace response
Dazzle reflex Palpebral refelx Pupillary light reflex Corneal reflex |
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What is tested with the menace response?
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Crude estimation of vision (tests retina, CN II, visual cortex, CN VII)
Not a reflex! |
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What is tested with the dazzle reflex?
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Abrupt bright light into eye usually causes blink (tests retina, CN II, CN VII, rostral colliculus, orbicularis oculi)
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What is tested with the palpebral reflex?
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Tests CN V, CN VII
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What does the pupilary light reflex test?
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Function of Retina
Optic nerve Midbrain Oculomotor nerve Iris Consensual PLR tests retina, CN II, midbrain, CN III |
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What does the corneal reflex test?
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When the cornea is touched, the animal should blink, and the globe should retract.
Tests CN V, CN VII, CN VI |
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What nerves should be blocked for an equine eye exam?
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Frontal nerve (sensory) - inject into supraorbital foramen
Palpebral nerve (motor) - inject along the lateral aspect of the highest portion of the zygomatic arch |
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What nerves should be blocked for a bovine eye exam?
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Palpebral nerve - inject along the zygomatic arch
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When would you use a retrobulbar block? What nerves does it block?
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Used to facilitate ocular and orbital surgery.
Blocks CN II, III, VI, IV, and the maxillary and ophthalmic branches of CN V |
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What is the difference between transillumination and retroillumination?
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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. |
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What is direct ophthalmoscopy?
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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. |
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What is indirect ophthalmoscopy?
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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. |
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What structures do you examine in the anterior aspect of the eye?
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Conjunctiva
Cornea Anterior chamber (aqueous flare, hyphema, hypopion) Iris (size of corpora nigra, color of iris, anterior synechia) Purkinje-Sanson reflexes |
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What drug do you use to dilate the pupil?
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Tropicamide 1% - takes 10-20 minutes to take effect and lasts 4-6 hours
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What structures do you examine in the posterior aspect of the eye?
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Lens position, opacities
Vitreous clarity, contents Fundus Retina Optic disk |
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What topical anesthetic is used for eye exams?
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Proparacaine 0.5%
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What is a tenometer used to measure?
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A tenometer measures intraocular pressure.
Normal pressure is 16-22 mmHg |
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When is the best time to take a culture sample from the eye?
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Culture should be performed prior to administration of any solution or ointment.
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What is the normal range for a Shirmer tear test?
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20-30 mm/60 seconds
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When is the best time to do a corneal scraping for cytology?
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After topical and local anesthesia have been performed.
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What layers of the cornea does fluorescein stain bind to?
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Binds to corneal stroma only
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What is inversion/rolling of the eyelid called?
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Entropion
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What are some treatment options for entropion?
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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. |
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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!
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How should eyelid lacerations be closed?
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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 |
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Clinical signs of corneal injury?
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Cloudy cornea (edema)
Vascularization Redness Cellular deposits Epiphora Drooping eyelid Blepharospasm Ocular discarge |
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What diagnostics should be done on a corneal ulcer?
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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 |
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What is the treatment for corneal ulceration?
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Abx oinment
+/- Antifungal ointment Cyclopegic (Atropine) Topical NSAIDS Anticollagenase ointment therapy (autologous serum) Systemic NSAIDS |
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What are some surgical treatment options for corneal ulceration?
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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) |
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What are some bad prognostic indicators for full thickness corneal lacerations?
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Laceration > 15mm
Involvement of the limbus Presence of keratomalacia or hyphema. |
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What is the most common ocular tumor of horses?
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Squamous cell carcinoma
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What is the most common peri-occular and skin tumor of horses?
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Equine sarcoid
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What are possible treatments for equine sarcoid?
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Surgical debulking/exision +/-:
Cryotherapy Cisplatin injection Topical chemotherapy Radiotherapy |
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What is the most common ocular cancer in cattle?
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Squamous cell carcinoma
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What procedure involves removal of the globe, conjuntiva, and 3rd eyelid?
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Enucleation
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What are indications for enucleation?
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Severe corneal infection and endophthalmitis
Corneal or adnexal neoplasia Orbital neoplasia Painful and blind eye |
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What is the most common peri-occular and skin tumor of horses?
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Equine sarcoid
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What are possible treatments for equine sarcoid?
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Surgical debulking/exision +/-:
Cryotherapy Cisplatin injection Topical chemotherapy Radiotherapy |
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What is the most common ocular cancer in cattle?
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Squamous cell carcinoma
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What procedure involves removal of the globe, conjuntiva, and 3rd eyelid?
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Enucleation
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What are indications for enucleation?
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Severe corneal infection and endophthalmitis
Corneal or adnexal neoplasia Orbital neoplasia Painful and blind eye |
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What procedure includes removal of all orbital contents (periorbita and globe)?
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Exenteration
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What are indications for exenteration?
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Large, malignant tumors of the orbit
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What procedure includes removal of the iris, lens, ciliary body, choroids, vitreous, and retina?
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Evisceration
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What is tarsorraphy?
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Suturing the eyelid closed to allow the eye to heal.
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