Ophthalmic Exam, Orbit Flashcards
What tests can be used to assess orbital symmetry?
- Orbital palpation
- Dorsal view assessment
- Retropulsion
The presence of _________ is pathognomonic for uveitis
Aqueous flare (turbidity of the anterior chamber)
assessed by Tyndall effect
Aqueous flare is visualized by the __________ effect
Tyndall
Which of the following cranial nerve tests do not assess/reflect vision?
1. Dazzle reflex
2. Pupillary light reflex (PLR)
What is considered a normal Schirmer tear test in dogs?
> 15 mm wetting/minute
What light source should be used to assess fluorescein staining on the eye?
Cobalt blue light
When using fluorescein stain, which areas of the eye are stained vs not stained?
- Stroma will stain bright green
- Epithelium and descemets membrane will not stain
(Stroma is hydrophilic and so is the fluorescein stain)
What are the 3 main uses of fluorescein staining?
- Corneal ulcers
- Nasolacrimal patency (Jones Test)
- Corneal perforation (Seidel Test)
What does a “positive Jones test” mean?
- Fluorescein stain leaking out of nostrils = Demonstrates normal nasolacrimal patency
What test can be used to assess nasolacrimal patency?
Jones test using fluorescein stain
What is a secondary finding in patients with a nasolacrimal obstruction?
Epiphora (tearing)
What is a positive Seidel test suggestive of?
Corneal perforation
(demonstrates aqueous leaking through the fluorescein stain
__________ can be used to measure intraocular pressure
Tonometry
What is the normal intraocular pressure in small animals?
10-20 mmHg
(Should be < 25 at all times)
What reading on tonometry is suggestive of glaucoma?
Pressure > 25 mmHg **with ** vision loss
What are low intraocular pressures consistent with?
Uveitis (Pressure < 10 mmHg)
You take 3 reading using a tonopen and get the following values: 15, 18, 22. Which reading is considered the most accurate reading?
15
(lowest reading is the most accurate)
What structures of the eye can be assessed with a fundic exam?
- Retina
- Tapetum
- Choroid
- Sclera
- Optic nerve
With of the following is false regarding direct vs indirect ophthalmoscopy?
A. Direct provides better magnification
B. Direct provides a greater depth of perception
C. Indirect is a safer technique in cases of aggressive patients
D. Indirect provides a larger field of view
E. Indirect creates an upside down and backwards image
B. Direct provides a greater depth of perception
Indirect = greater depth of perception
List the 4 classic clinical signs of Horners syndrome?
- Ptosis
- Enophthalmos
- Miosis
- Protrusion of the 3rd eyelid
What is phthisis bulbi?
An acquired shrunken globe, most often from severe/chronic inflammation
Inflammation of what salivary gland can result in displacement of the globe?
Zygomatic salivary gland
Why are mouth gags avoided in cats?
Risk of blindness due to compression of the maxillary and carotid arteries leading to decreased blood flow
Paralysis of the ___________ muscle can lead to ptosis
Levator palpebrae muscle (CN III)
What cranial nerves are located near the cavernous sinus?
CN III, IV, V, VI
What ophthalmic findings can be seen with cavernous sinus syndrome?
- External ophthalmoplegia
- Internal ophthalmoplegia (mydriasis)
- Ptosis
- Reduced corneal and medial canthal sensation
- Reduced lateral canthal sensation
- Abnormal CN exam!!
Why do horses and ruminants have more protection from ocular trauma that cats and dogs?
Complete orbital ring unlike in dogs and cats who rely on orbital ligament
Do dogs or cats have a shorter orbital ligament?
Cats (more boney protection relative to dogs)
What factors make brachycephalics very susceptible to ocular disease and injuries?
- Longer orbital ligament than normal dogs, less boney protection
- Much shallower orbit
What associated clinical signs can be seen with exophthalmos?
- 3rd eyelid protrusion
- Facial swelling
- Pain when opening the mouth
- Soft palate bulging
- Fever
What are the causes of exophthalmos?
1. Orbital neoplasia
2. Orbital cellulitis/abscess
3. Zygomatic salivary gland mucocele
4. Masticatory myositis
5. Extraocular myositis
6. Retrobulbar hemorrhage
(1 and 2 are most common)
Which of the following occurs with glaucoma?
A. Exophthalmos
B. Buphthalmos
B. Buphthalmos
What is the treatment protocol for patients with orbital cellulitis/abscess?
- NSAIDs/Steroids + Abx
- Surgical exploration and/or drainage
What is the treatment protocol for patients with orbital neoplasia?
- Globe sparing (palliative)
- Globe removal via enucleation or exenteration
What is the difference between enucleation and exenteration?
Enucleation - removal of the eye
Exenteration - removal of eye AND all orbital structures
When performing an enucleation, especially on cats, what complication can occur?
Direct tension on the optic nerve can cause blindness in the normal unaffected eye
What other clinical findings can be seen in a patient with enophthalmos?
- Facial muscle atrophy
- Third eyelid protrusion
- Entropion
List the causes of enophthalmos
Orbital volume imbalances
1. Dehydration
2. Emaciation
3. Myopathies
4. Space occupying lesions
Active globe retraction
1. Ocular pain (CN VI causes retractor bulbi to retract eye)
Passive globe retraction
1. Horner’s syndrome (sympathetic dysfunction)
What congenital condition can result in ventrolateral divergent strabismus?
Hydrocephalus
What cranial nerves can cause acquired strabismus?
CN III, IV, and VI
What indicates a better prognosis if proptosis occurs?
1. Brachycephalics
2. < 3 extraocular muscles torn
3. Positive direct and consensual PLRs (intact vision)
What indicates a poor prognosis if proptosis occurs?
- Cats
- Doliocephalic dogs
- > 3 extraocular muscles torn
- Ruptured eye
- Hyphema
- Orbital fractures
What is the treatment protocol for a patient with proptosis?
- Put eyeball back in
- Temporary tarsorrhaphy (suture eye closed)
- Lubricate cornea
- Topical Abx
- Pain management
- Sutures in for 3 weeks
What are the major complications that can occur with post-op proptosis?
- Corneal ulceration
- Loosening of sutures
- Strabismus
- KCS
- Blindness
- Repeated proptosis
