Ophthalmology Flashcards
OS
Left Eye
OD
Right Eye
OU
Both Eyes
What does the cotton ball test assess?
Vision - needed to track the cotton ball
Phototopic Maze Test
Tests vision in bright and navigating
Scotopic Maze
Tests navigating the maze in dim light
What cranial nerves are assessed with the Palpebral reflex?
CN V (afferent) CN VII (efferent)
What cranial nerves are assessed with the Menace response?
CN II (afferent) CN VII (efferent)
What cranial nerves are assessed with the Pupillary light reflex?
CN II (afferent) CN III (efferent)
What cranial nerves are assessed with the Dazzle Reflex?
CN II (afferent) CN VII (efferent)
What cranial nerves are assessed with the Oculocephalic reflex?
Intact CN II peripheral and central vestibular components CN III CN IV Cn VI
What cranial nerves are assessed with the Corneal reflex?
CN V (afferent) CN VI and VII (efferent)
What are the guidelines for a normal Schirmer Tear Test for a dog?
greater than 15mm wetting/minute
What are the three common uses of Fluorescein stain?
Diagnosis and characterization of corneal ulceration
Demonstration of nasolacrimal patency (Jones Test)
Demonstration of corneal performation (Seidel Test)
What does the Jones Test assess?
Demonstration of nasolacrimal patency
What does the Seidel Test assess?
Demonstration of corneal perforation
What does a positive Jones Test demonstrate?
nasolacrimal patency
What does Tonometry measure?
intraocular pressure in mmHg
What is a normal reading for Tonometry for cats and dogs?
10-20mmHg
What is the diagnosis for a Tonometry reading of greater than 25mmHg with vision loss?
Glaucoma
What is the diagnosis for low intraocular pressures?
Uveitis
Adnexa
everything that supports the eyeball
Specular Reflection
Mirror-like feature of the eye
What does a disturbance of the Specular reflection mean?
Irregularity of the ocular surface
Boney orbit
a part of the adnexa, the conical boney structure that contains the eyeball and periorbital cone
Periorbital cone
Supportive cone like structure that contains the eyeball, extraocular muscles, fat, vessels, nerves, and fascia that reside within the orbit
Orbital Ligament
ligamentous structure that forms the lateral boundary of the boney orbit in cats and dogs
Exopthalmus
Abnormal protrusion of the eye from the orbit. The position is abnormal. The globe size is normal
Buphthalmos
“cow eye” but refers to the abnormal enlargement of the eyeball
What causes Buphthalmos?
glaucoma
Enophthalmos
Abnormal recession of the eye within the orbit
Strabismus
deviation of one or both eyes, so that both eyes are not directed at the same object
Horner’s Syndrome
sympathetic denervation to the eye and ocular adnexa.
What are the clinical signs of Horner’s Syndrome?
Enophthalmos
Ptosis
Miosis
Protrusion of the third eyelid
Microphthalmos
a congenitally small and malformed globe
Phthisis bulbi
an acquired shrunken globe, most often from severe or chronic inflammation
Proptosis
Anterior displacement of the globe such that the eyelids are caught behind the equator of the globe
What can induce orbital or periorbital disease?
Dental disease especially from the carnassial tooth
What can cause displacement of the globe?
Inflammation of the Zygomatic salivary gland
What can cause temporary or permanent blindness in cats?
The use of Mouth Gags
What is different about orbital anatomy of the dog and cat?
Open orbit with an orbital ligament
What is different about orbital anatomy in ruminants and horses?
Closed orbit
What are the clinical signs associated with Exophthalmos?
Third eyelid protrusion Facial swelling Soft palate bulging Pain opening mouth Fever
What is the most common cause of exophthalmos?
Orbital volume imbalance
What is a non-painful cause of Exophthalmos?
Orbital neoplasia
What causes acute onset painful Exophthalmos in working dogs and stick chewers?
Orbital Cellulitis
What can causes Lateral deviation in orbital disease?
Tumor involving the third eyelid
Strabismus
deviation of one or both eyes, so that both eyes are not directed at the same object
What are the treatments for Orbital Neoplasia?
Globe sparing:
Radiation
Surgical exploration
Chemotherapy
Globe removal:
Enucleation
Exenteration
Exenteration
removal of the eye and all orbital contents
What are the treatment approaches for Orbital cellulitis?
NSAIDs
Antibiotics
Surgical exploration and/or drainage
What are the common clinical signs of Enophthalmos?
Facial muscular loss (unilateral or bilateral)
Third eyelid protrusion
Entropion
What are the three common mechanisms of Enophthalmos?
Orbital volume imbalances
Active globe retraction
Passive glove retraction
What are the common causes of Enophthalmos?
Dehydration Emaciation or cachexia Myopathies Space occupying lesions anterior to the globe Ocular pain Horner's Syndrome
What are the congenital Strabismus?
Divergent strabismus in brachycephalic dogs
Convergent strabismus in Siamese Cats
Ventrolateral divergent strabismus in Hydrocephalus
What are the acquired causes of Strabismus?
Mechanical or nervous dysfunction of any rectus muscle
Imbalance of orbital volume
What are the two considerations in the prognosis of Proptosis?
Vision?
Globe retention?
Tarsus
The fibrocartilagenous layer of the eyelid that contains the meibomonian glands. This is the holding layer for surgical eyelid closure
Meibomian glands
These are glands within the tarsal layer of the eyelid that produce lipid, or sebum, to the tear film, This is the outermost, or most external layer of the three-layered tear film
Lateral canthus
the lateral, or temporal convergence of the upper and lower eyelids
Medial canthus
the medial, or nasal convergence of the upper and lower eyelids
Palpebral fissure
the area outlined by the upper and lower eyelid margins
Ptosis
drooping of the eyelids (most often evident by upper eyelid drooping) cause by sympathetic denervation to the eyelid.
Lagophthalmos
incomplete eyelid closure/coverage of the eyeball
Eyelid margin
identified by the”grey line” of Meibomian gland orifices. This is an important landmark to identify when closing the eyelid surgically
Entropian
rolling in the eyelid margin such that hairs are touching the ocular surface
Ectropion
the outward rolling of the eyelids. Animal will often develop exposure keratitis or conjunctivitis due to the poor ability of the eyelids to completely close over the ocular surface
Blepharospasm
Spasm of the orbicularis oculi muscle resulting in eyelid closure.
AKA squinting
Tarsorrhaphy
A surgical procedure in which the eyelids are sutured together. This can be temporary or permanent, and can be partial (closing only a portion of the eyelid) or complete (closing the entire eyelid)
Trichiasis
Hairs growing from normal skin reach the corneal and /or conjunctival surface. Technically speaking, entropion causes trichiasis, however, trichiasis is most often used to describe hairs from the nasal folds (nasal fold trichiasis) that are directed toward the eye in brachycephalic dog breeds.
Distichia
cilia (eyelashes) which emerge from Meibomian (tarsal) glands.
Ectopic cilia
cilic (eyelashes) protruding through the palpebral conjunctiva. These hairs typically cause severe, intermittent pain and often cause corneal ulceration. They most commonly arise from the 12 o’clock eyelid position
What muscle closes the eyelids like a zipper?
Orbicularis oculi
What Cranial nerve innervates the Orbicularis oculi?
CN VII
What is caused by dysfunction of the CN VII?
Lagophthalmos
What muscle is innervated by the CNIII to open the upper eyelid?
Levator palpebrae superioris
What nerve innervates the Levator palpebrae superioris?
CN III
What is caused by dysfunction of the CNIII?
ptosis
What muscle opens the upper eyelid due to the sympathetic nervous system?
Muller’s muscle
What is caused by dysfunction of the Muller’s muscle?
ptosis
What layer supports the Meibomian glands?
tarsus layer
Anatomic entropion
the eyelids are not appropriately conformed to the eye and its presence is unrelated to ocular pain
Blepharospasm associated entropian
ocular pain stimulates active glove retraction and an altered eyelid to eye relatioship
What are the hereditary causes of Anatomic entropion?
Abnormal canthus in brachycephalic dogs
Abnormal palpebral fissure in Hounds and giant breeds
Excessive facial folds in Shar Pei
What are the acquired causes of Anatomic entropion?
Enophthalmos
Blepharospasm that alters anatomy
What should you consider with Anatomic Entropion caused by Blepharospasm?
Chronic corneal ulceration
Dry eye
Conjunctivitis
How do you differentiate anatomic and blepharospasm entropion?
Take away the ocular pain that induces blepharospasm
What is a common cause of Entropion in foals?
Septic dehydration
What is a temporary treatment for Entropion?
Viscous lubrication
Eyelid tacking
Partial temporary tarsorrhapy
What is a permanent treatment for Entropion?
Modified Hotz-Celsus - rolls out the eyelid
What is a common cause of Ectropion?
Iatrogenic: aggressive entropion correction
Hereditary: Hounds and giant breeds
What are 4 common causes of Lagophthalmos?
Breed variation
Exophthalmos
Buphthalmos
CN V or CN VII dysfunction
What is caused by secondary eye exposure from Lagophthalmos?
Keratoconjunctivitis
How do you treat Lagophthalmos temporarily?
Lubrication or temporary tarsorrhaphy
How do you treat Lagophthalmos permanently?
permanent partial tarsorrhaphy or canthoplasty
What nerve innervates the eyelid for sensory?
CN V (maxillary or ophthalmic branches
What nerves innervate the 3 muscles of the eyelid?
CN III (Open) CN VII (close)
What causes an abnormal palpebral reflex?
CN V
CN VII
What are the clinical signs of Horner’s Syndrome?
Miosis
Enophthalmos
Protrusion of the third eyelid
Ptosis
What causes the clinical signs of Horner’s Syndrome?
Disruption of innervation to the Muller’s Muscle, Iris dilator, or Periorbital cone
What are the common causes of Horner’s Syndrome?
Otitis
Nasopharyngeal polyps
Iatrogenic: venipuncture or feeding
Idiopathic
How do you diagnose Horner’s Syndrome?
Dilute phenylephrine (0.1%). 1 drop to both eyes
What three conditions cause irritation to the cornea or conjunctiva?
Trichiasis
Distichiasis
Ectopic Cilia
What breeds are commonly affected by Trichiasis?
Brachycephalic
What is the treatment for Trichiasis?
Lubrication
Facial fold resection
In what breeds would you find Distichia?
Cockers
Poodles
Sheepdogs
What is the treatment for Distichia?
Cryotherapy and plucking of the hairs
What breed is Ectopic cilia common in?
Brachycephalic breeds
How do you treat Ectopic cilia?
Cryotherapy with hairs sharply excised
What type of tumor is Canine eyelid tumors?
benign
What type of tumor is feline eyelid tumors?
malignant
What is the most common eyelid tumor in dogs?
Meibomian gland adenoma
What are the surgical considerations for removing Canine eyelid tumors?
Irritation to the ocular surface?
Size
Location
How do you treat Canine eyelid tumors?
Debulk and cryotherapy
Complete excision
What are the 4 key concepts to closure of eyelid margin defects?
- Limited debridement
2/ Closure must be perfect - Avoid full thickness suture bites
- The tarsus is holding layer
What is important about the figure 8 suture pattern used to correct eyelid margin defects?
Knot and suture are directed away from the cornea
What is the purpose of the third eyelid cartilage?
Gives the third eyelid shape and structure
Performs a squeegee like function
Supports the gland of the third eyelid
What is caused by Prolapse of the third eyelid?
Chronic conjunctivitis
Keratoconjunctivitis sicca
What is the treatment for prolapse of the third eyelid?
Morgan pocket technique
Orbital tacking
Conjunctival fornix
The area where palpebral conjunctiva meets bulbar conjunctiva
Palpebral and Bulbar conjunctiva
Conjunctiva that lines the inner surface of the eyelid and the anterior aspect of the globe respectively
Epiphora
Abnormal overproduction of tears. This is common response to ocular irritation
Conjunctival lymphoid follicles
a response to non-specific antigenic stimulation. Presence of these follicles anywhere but the bulbar surface of the third eyelid is considered abnormal and consistent with a diagnosis of conjunctivitis
Goblet cells
These are present in conjunctival epithelium and have produce the innermost mucus layer of the three-layered tear film. Patients with conjunctivitis will often overproduce mucus, conventionally referred as mucus discharge
Mucoid discharge
a very common clinical sign with conjunctivitis
Mucopurulent discharge
most commonly found in cases of keratoconjunctivitis sicca (KCS), due to loss of the aqueous portion of the tear film which then causes mucus overproduction, bacterial overgrowth and subsequent white blood cell recruitment. This is a classic feature of KCS and will be very important to remember
Conjunctival hyperemia
describe congestion of the superficial vessels of the conjunctiva. Predominance of this finding suggests superficial disease. For instance, tear film disorders (KCS), primary conjunctivitis, eyelid disorders causing secondary conjunctivitis, a response to superficial cornea ulceration etc.
Episcleral injection
congestion of deep conjunctival vessels known as episcleral vessels. Predominance of this clinical signs suggests deeper disease processes. For instance uveitis, glaucoma, and deep/complicated corneal ulceration
Keratitis
Inflammation of the cornea. Clinical signs include corneal neovascularization (Most common), corneal pigmentation, corneal fibrosis, corneal ulceration and white blood cell infiltration
Symblepharon
Permanent adhesion between the conjunctiva and the cornea
Ghost vessels
non-perfused corneal blood vessels. These blood vessel tracks provide evidence of previous keratitis
Chemosis
edema of the conjunctiva
What are the clinical signs of Allergic Conjunctivitis?
Blepharospasm Epiphora Mucoid discharge Hyperemia Lymphoid follicles
What is the treatment for Allergic Conjunctivitis?
Steroid: Neomycin-Polymixin - Dexamethasone
NSAID: Diclofenac
T-cell inhibitor: Cyclosporine
What is the function of tear film?
Nourish
Cleanse
Protect
What secretes the Oil/Lipid layer of the tear film?
Meibomian gland
What secretes the Aqueous layer of tear film?
Lacrimal and gland of the third eyelid
What secretes the Mucinous layer of the tear film?
Conjunctival goblet cells
What is the most common cause of Keratoconjunctivitis sicca?
Immune-mediated destruction
What are the causes of Keratoconjunctivitis sicca?
Immune mediated destruction Excision of the gland of the third eyelid Drugs Trauma Neurogenic Infectious
Xeromycteria
Dry nose
With what test do you diagnose Quantitative KCS?
Schirmer tear test
What is the most common cause of conjunctivitis in dogs?
Bacterial
What are the two categories of KCS?
Qualitative
Quantitative
What virus causes KCS?
Canine Distemper Virus
Qualitative KCS
Lipid or mucin deficiency
What are the clinical signs of Keratoconjunctivitis sicca?
Keratitis: Superficial corneal neovascularization Corneal fibrosis Superficial corneal pigmentation Corneal ulceration White blood cell infiltration Hyperemia
Conjunctivitis:
Mucopurulent discharge