Term
| Which eye is denoted by OD? |
|
Definition
|
|
Term
| Which eye is denoted by OS? |
|
Definition
|
|
Term
| Which eye is denoted by OU? |
|
Definition
|
|
Term
| In which species is the boney orbit complete? |
|
Definition
herbivores and primates
*in carnivores the lateral orbital ligament forms the superiotemporal boundary (carnivores are more predisposed to proctosis) |
|
|
Term
| What are the extraoccular muscles that comprise the orbital cone? |
|
Definition
1. lateral, medial, dorsal, ventral rectus
2. superior and inferior obliques
3. retractor bulbi |
|
|
Term
| Which cranial nerve innervates the superior, inferior, and medial rectus muscles and what is the function of these muscles? |
|
Definition
| All are innervated by CN III (oculomotor) and act to rotate the globe of the eye in the direction of their names |
|
|
Term
| Which of the extraocular rectus muscles is innervated by CN VI (abducens), and what is the function of this muscle? |
|
Definition
| Lateral rectus, acts to rotate the globe of the eye laterally |
|
|
Term
| What is the innervation to retractor bulbi mm? What is its function? |
|
Definition
Innervated by CN VI (abducens) and acts to retract globe of the eye into the socket
*particularly well developed in herbivores |
|
|
Term
| Which of the extraocular muscles is comprised of smooth muscle? What is its function? |
|
Definition
| the orbitalis muscle encircles the extraocular muscle cone; sympathetic stimulus results in contraction that push the globe of the eye forward in the socket and also help to keep the eyelids open |
|
|
Term
| Which of the eyelid muscles is voluntary (ie. skeletal) and what is its innervation and function? |
|
Definition
| Levator palpebrae superioris is innervated by CN III (oculomotor) and functions to elevate the superior eyelid |
|
|
Term
| Which of the eyelid muscles is composed of smooth muscle? What is its function? |
|
Definition
| Mueller's mm. contract tonicaly to widen the palpebral fissure in response to sympathetic stimulus (ie. elevates the superior eyelid and depresses the lower eyelid) |
|
|
Term
| Which eyelid muscle is responsible for blinking? What is its innervation? |
|
Definition
| orbicularis oculi, innervated by CN VII (facial) |
|
|
Term
| What is the "Grey Line" along the inner surface of the eyelids? |
|
Definition
|
|
Term
| Which orbital glands are responsible for producing the watery fraction of tear secretions? |
|
Definition
| orbital lacrimal gland (located in the superior-temporal orbit) and the 3rd eyelid gland (located at the base of the 3rd eyelid) |
|
|
Term
| Which anatomical apparatus is responsible for tear film drainage? Name the components of this apparatus in order from proximity to the eyeball. |
|
Definition
| nasolacrimal apparatus, comprised of the superior and inferior puncta and canaliculi which join together at the nasolacrimal sac and then continue as a single nasolacrimal duct that terminates at the nasal punctum |
|
|
Term
| What surfaces of the eye are lined by conjunctiva? |
|
Definition
| the inner lining of the eyelids, entirety of the 3rd eyelids, and the sclera up to the cornea |
|
|
Term
| histologically characterize the conjunctiva, what is its role? |
|
Definition
| nonkeratinized stratified squamous epithelium with goblet cells that produce mucus component of tear film, also functions to protect the cornea |
|
|
Term
| What are the three tunics that surround the optical media of the eye? |
|
Definition
-fibrous tunic (cornea/sclera)
-uveal tunic (iris/ciliary body/choroid)
-neural tunic (neurosensory retina/retinal pigmented epithelium) |
|
|
Term
| What are the components of the cornea? |
|
Definition
surface epithelium (non-keratinized stratified squamous)
stroma (very orderly collagen fibrils),
descemet's membrane (very thick BM of corneal endothelium)
endothelium (cellular monolayer) |
|
|
Term
| Why is the sclera white but the cornea clear? |
|
Definition
| the collagen fibrils of the sclera or less orderly in their organization resulting in gross opacity |
|
|
Term
| What is the name of the corneoscleral junctino (usually visible grossly as a darkly pigmented ring surrounding the iris) |
|
Definition
|
|
Term
| What is the name of the site where the optic nerve exits the back of the sclera? |
|
Definition
lamina cribosa
*not really a hole, rather collagen fibrils of the sclera form a seive that is penetrated by axons of the optic nerve |
|
|
Term
| the uvual tract of the eye can also be called _____ |
|
Definition
| middle vascular layer = iris/ciliary body/choroid |
|
|
Term
| What two muscles are located in the iris? |
|
Definition
iris sphincter (circumfrentially arranged)
dilator mm (radially arranged)
these are smooth muscles in mammals and skeletal muscles in birds/reptiles |
|
|
Term
| Iris color is the result of what anatomic component? |
|
Definition
| bilayered posterior pigmented epithelium |
|
|
Term
| What are the two regions of the ciliary body and what are they lined by? |
|
Definition
Pars plicata (has finger-like processes)
Pars plana (posterior to plicata, smooth)
both regions are lines by bilayered epithelium (outer layer is pigmented, inner layer is non-pigmented) |
|
|
Term
| What anatomic component of the eye is responsible for producing the aqueous humor? |
|
Definition
| non-pigmented ciliary body epithelium (inner layer) |
|
|
Term
| What structure suspends the lens? |
|
Definition
| the zona ligaments (extend from the processes of the ciliary body pars plicata to the lens equator) |
|
|
Term
| What is the function of the smooth muscles associated with the ciliary body? |
|
Definition
| adjustment of the lens for visual accommodation |
|
|
Term
| Where does aqueous humor circulate out of the eye? |
|
Definition
| at the iridocorneal angle |
|
|
Term
| What is the route of aqueous humor outflow? |
|
Definition
| produced by the non-pigmented epithelium of the ciliary body --> posterior chamber --> pupil --> anterior chamber --> iridocorneal angle --> vortex veins --> systemic circulation |
|
|
Term
| Where is the tapetum lucidum located in the posterior uvea? |
|
Definition
| triangular area located in the superior fundus cellular in carnivores fibrous in ungulates |
|
|
Term
| What are the three components of the inner neural tunic of the eye? |
|
Definition
neurosensory retina
retinal pigment epithelium
optic nerve |
|
|
Term
| What is the definition of the fundus? |
|
Definition
| composite view of the back of the eye |
|
|
Term
| What is the function of the retinal pigment epithelium (RPE)? |
|
Definition
| RPE cells interdigitate with the rods and cones and act as nurse cells, separation of the rods and cones from RPE results in blindness in the region of detachement |
|
|
Term
| Where is the retina firmly attached to the choroid? |
|
Definition
| along the peripheral retina and at the optic nerve head ONLY |
|
|
Term
| What is the optic nerve composed of? |
|
Definition
| retinal ganglion cell axons |
|
|
Term
| What are the boundaries of the anterior chamber? |
|
Definition
| cornea to lens-iris diaphragm |
|
|
Term
| What is the vitreous humor composed of? |
|
Definition
| collagen, glycosaminoglycans, water |
|
|
Term
| What is an important mechanism that helps hold the retina in place? |
|
Definition
| gentle pressure of the vitreous humor helps to hold the retina in place |
|
|
Term
| What three tests comprise the minimal ophthalmic database? |
|
Definition
schirmer tear test (measure aqueous component of tear film)
fluorescein stain (assess integrity of the cornea)
tonometry (quantify intraocular pressure) |
|
|
Term
| If patients have difficulty seeing only in dim light what part of the eye is compromised? |
|
Definition
|
|
Term
| What are some clinical signs indicative of ocular discomfort? |
|
Definition
| pawing/rubbing eyes, squinting, tearing |
|
|
Term
| When should you perform a schirmer tear test in the context of the ophthalmic exam? |
|
Definition
| BEFORE cleaning/rinsing/medicating the eye |
|
|
Term
| Why does fluorescein stain detect corneal ulceration? |
|
Definition
floursecein stain binds to hydrophilic substrates, the intact corneal epithelium is hydrophobic but the underlying corneal stroma is hydrophilic
*can be best appreciated with cobalt filter |
|
|
Term
| What is the jones test and what is it used to assess? |
|
Definition
| Jones test is used to assess patency of nasolacrimal system. Following application of flourescein stain to the eye, dye should drain through the nasolacrimal system and appear bilaterally at the nostrils |
|
|
Term
| What is a descemetocoele? |
|
Definition
| a corneal ulcer that extends through the entire thickness of the corneal stroma down to descement's membrane |
|
|
Term
|
Definition
| vital dye that stains dead/dying epithelial cells, can be used to identify corneal erosions that have not yet progressed to ulcers |
|
|
Term
| What should you do to further assess patency of nasolacrimal system following a negative jones test? |
|
Definition
cannulate superior punctum and flush with saline --> look for flush at inferior punctum, then occlude inferior punctum with finger ---> flush and look for saline at nares
*this may be easier retrograde (via nasal meatus) in horses |
|
|
Term
| pupilary light reflect measures the effect of what stimulus on what receptor? |
|
Definition
| PLR measures the effect of light on the retina |
|
|
Term
| What are the afferent and efferent nerves responsible for facilitating the Pupilary light reflex? |
|
Definition
afferent is the optic nerve (from the retina, in response to light)
efferent is the occulomotor (CN III) to the iris sphincter muscles --> pupil constriction both in the direct and consensual eye (due to decussation of optic nerve fibers at optic chiasm) |
|
|
Term
| What are the afferent and efferent nerves responsible for facilitating the menace response (NOT a reflex)? |
|
Definition
afferent is the optic nerve (from the retina, in response to sensation of motion towards the eye)
efferent is the facial nerve (CN 7) to the orbicularis oculi muscle --> blink |
|
|
Term
| What are the afferent and efferent nerves responsible for facilitating the corneal and palpebral reflexes? |
|
Definition
Afferent is the trigeminal nerve (CN 5) in response to touch
effernt is the facial nerve (CN 7)to orbicularis oculi muscle --> blink |
|
|
Term
| What are the afferent and efferent nerves responsible for facilitating the dazzle reflex? |
|
Definition
afferent is the optic nerve (from the retina, in response to a very bright light)
efferent is the facial nerve (CN 7) to the orbicularis oculi muscle --> blink |
|
|
Term
| What is an ophthalmoscope used for? |
|
Definition
|
|
Term
| What should you assess with distance examination, bright focal light held at arm's length? |
|
Definition
| bright focal light held at a distance from the eye results in retroillumination of light reflected back by the tapetum and occular media, opacities are visible as dark shadows, and pupil symmetry can also be assessed |
|
|
Term
|
Definition
|
|
Term
|
Definition
| rolling out of the eyelid |
|
|
Term
| How is conjunctival hyperemia differentiated from episcleral injection? |
|
Definition
conjunctival hyperemia is a diffuse redding secondary to engorgement of fine caliber vessels
episcleral injection is visible as linear engorgement of larger caliber straight vessels |
|
|
Term
| What type of occular disease is associated with conjunctival hyperemia vs. episcleral injection |
|
Definition
hyperemia: occular surface diseases
injection: intraoccular diseases |
|
|
Term
| What anatomic features are assessed during the anterior segment examination? |
|
Definition
| cornea, anterior chamber, iris/pupil, lens |
|
|
Term
| What is the best method of examination to assess color and texture of lesions within the anterior segment of the eye? |
|
Definition
| direct illumination (bright focal light held close to the eye) |
|
|
Term
| How is the anterior segment of the eye assessed? |
|
Definition
focused slit beam projected obliquely through the eye *this is a method of lesion localization
(1st purkinje image = cornea
2nd purkinje image = anterior lens capsule
3rd purkinje image = posterior lens capsule) |
|
|
Term
| the first purkinje image correlates with what part of the eye? |
|
Definition
|
|
Term
| The second purkinje image correlates with what part of the eye? |
|
Definition
|
|
Term
| the 3rd purkinje image correlates with what part of the eye? |
|
Definition
|
|
Term
| T/F: you CANNOT see the beam of a slit lamp through the anterior chamber of the eye |
|
Definition
TRUE
*beam projects only as far as the posterior lens capsule |
|
|
Term
| What drug is used to dilate the pupil and facilitate fundic exam? |
|
Definition
| tropicamide (short acting topical anticholinergic that paralyzes the iris sphincter muscle) |
|
|
Term
| Which is better to screen the fundus for pathology, direct or indirect ophthalmoscopy? |
|
Definition
indirect is better because it involves less magnification resulting in a wider field of view
*downside: image is inverted and upside down so it takes some practice to orient yourself |
|
|
Term
| What are three methods of lesion localization? |
|
Definition
purkinje images (lesions in anterior segment)
object overlay
direct ophthalmoscope (based on diopter setting) |
|
|
Term
| When should you culture the cornea, what is the best location to collect a sample? |
|
Definition
| cultutre cornea if ulcerated, obtain sample from the margins of the ulcer |
|
|
Term
| How can you assess the electrical function of the retina? |
|
Definition
|
|
Term
| From what direction is facial, orbital, and globe symmetry best assessed? |
|
Definition
| look down on the head from above |
|
|
Term
| What is the most important reason for resistance to retropulsion of the globe in the orbit? |
|
Definition
| space occupying mass within the orbit |
|
|
Term
| Why is an oral examination an important part of the orbital exam? |
|
Definition
evalute pterygopalatine fossa for foreign bodies, swelling, or hyperemia which could result in/from inflammatory orbital disease <-- also supported by pain concurrent with opening the mouth
if non-painful but restricted range of movement when opening the mouth consider neoplasia (ie. non-inflammatory) |
|
|
Term
|
Definition
| globe recessed in orbit (eye may appear smaller because it's sunken in), third eyelid is often elevated |
|
|
Term
| What are some diseases/conditions that may result in enophthalmos (globe rescessed in orbit)? |
|
Definition
-space occupying lesion anterior to the globe of the eye (ex. third eyelid carcinoma)
-decrease in orbital volume (secondary to orbital fat atrophy (geriatric/starvation), dehydration, post-inflammatory fibrosis)
-loss of orbitalis m. tone (horner's syndrome) |
|
|
Term
| How can you differentiate enophthalmos (recessed globe) from micropthalmos (congenitally small globe) or phthisis bulbi (small globe secondary to disease)? |
|
Definition
| assess corneal diameter, should be the same in both eyes with enophthalmos (recessed globe) but decreased in affected eye with microphtalmus/phthisis bulbi |
|
|
Term
|
Definition
| protrusion of the globe secondary to a space occupying lesion within the orbit |
|
|
Term
| What other occular abnormalities often accopany exopthalmos (protrusion secondary to space-occupying lesion w/in orbit)? |
|
Definition
lagophthalmos (inability to blink)
-secondary exposure keratits
strabismus (deviation of globe)
increased scleral show
+/- third eyelid elevation |
|
|
Term
|
Definition
| inability to blink --> often results in exposure keratitis |
|
|
Term
|
Definition
|
|
Term
| How can you differentiate exophthalmos (protruded globe) from buphthalmos (enlarged globe)? |
|
Definition
assess CORNEAL DIAMETER --> equal with exophthalmos, increased with buphthalmos
also, resistance to retropulsion with exophthalmos |
|
|
Term
|
Definition
| extreme form of exopthalmos, globe of the eye is essential out of the orbit, usually traumatic |
|
|
Term
| T/F: microphthalmos (congenitally small globe) is usually associated with small palpebral fissure and orbit, other congentical ocular defects, and merle coat color |
|
Definition
|
|
Term
| What breed is predisposed to congenital convergent strabismus? |
|
Definition
siamese cats
*inherited autosomal recessive |
|
|
Term
| Brachycephalic dogs often have what incidental abnormality in eye positioning? |
|
Definition
|
|
Term
| What is the mechanism behind horner's syndrome? What clinical signs are expected? |
|
Definition
loss of sympathetic innervation to the orbit --->
ptosis (drooping eyelid <- meuller's m.)
miosis (small pupil <- iris dilator m.)
enophthalmos (recessed globe <- orbitalis m.)
protrusion of 3rd eyelid (passive secondary to enophthalmos)
*horses + ipsilateral sweating/facial vascular hyperemia (vasodilation)
*cows + ipsilateral dry nasal planum |
|
|
Term
| What is the pathway of sympathetic innervation to the orbit? |
|
Definition
| hypothalamus --> preganglionic neuron (T1-T3) --> cranial cervical ganglion (autonomic) --> postganglionic neuron --> branches of CN V (trigeminal) |
|
|
Term
| What is the most common etiology of horners? |
|
Definition
Idiopathic --> often spontaneously resolves
also assocaited with: trauma, otitis media, intracranial neoplasia |
|
|
Term
| How do you diagnose Horner's syndrome? |
|
Definition
Phenylephrine: adrenergic agonist
application should resolve clinical signs, treatment requires identification of underlying cause |
|
|
Term
| What are clinical signs associated with orbital cellulitis/abcesses? |
|
Definition
acute onset, 3rd eyelid protrusion, exophthalmos, resistance to retopulsion, pain on opening the mouth, swollen hyperemic pterygopalatine fossa
+/- fever and inflammatory leukogram |
|
|
Term
| What is the treatment of choice for a defined orbital abscess? |
|
Definition
drainage via the oral cavity, obtain sample for culture and sensitivity, flush with saline
*risk* laceration of palatine artery, injury to globe or optic nerve --> blindness |
|
|
Term
| What breed is predisposed to extraocular polymyositis? What clinical signs are consistent with this? |
|
Definition
Golden Retrievers
bilateral exophthalmos, divergent strabismus and excessive scleral show |
|
|
Term
| What therapy is used to treat extraocular polymyositis? |
|
Definition
| long term systemic immunosuppression |
|
|
Term
| Why might extraocular polymyositis progress to enophthalmos with chronicity? |
|
Definition
| post inflammatory fibrosis and atrophy of the extraoccular muscles |
|
|
Term
| What is the most common primary orbital neoplasia? |
|
Definition
lacrimal gland/3rd eyelid gland adenoma or adenocarcinoma
also fibrosarcoma, optic nerve glioma, meningioma |
|
|
Term
| What are the two most common types of neoplasia that metastasize to the orbit? |
|
Definition
squamous cell carcinoma and lymphoma
*also nasal carcinoma(usually via local extension through the maxilla) |
|
|
Term
|
Definition
| removal of the globe and sew the lid shut |
|
|
Term
| What is excenteration, under what circumstances is this procedure indicated? |
|
Definition
removal of the globe and orbital contents
tx neoplasia and or infection |
|
|
Term
| What is evisceration? When is this procedure contraindicated? |
|
Definition
| removal of intraocular contents leaving the corneo-scleral shell with prosthesis implant contraindicated with intraocular neoplasia or infection (do exenteration instead) |
|
|
Term
| What are the two main functions of the eyelids? |
|
Definition
corneal protection
production, distribution, and drainage of tear film |
|
|
Term
| What are two congenital eyelid diseases? |
|
Definition
eyelid agenesis (aka eyelid coloboma, usually temporal superior lid)
dermoid (haired skin in an aberrant location) |
|
|
Term
| What are the consequences of congenital eyelid agenesis/coloboma? |
|
Definition
inability to blink normally --> exposure keratitis
also conjunctivitis and trichiasis (hair touching the cornea) |
|
|
Term
| What are the treatment options for eyelid agenesis/coloboma? |
|
Definition
medical management: 3-4X daily lubrication of cornea
surgical reconstruction: wait until after 5-6 months of age to accomodate growth |
|
|
Term
|
Definition
| normal tissue in an aberrant location (ie. dermoid= normal haired skin in an aberrant location (cornea,conjunctiva, eyelid) |
|
|
Term
| What is the treatment for dermoids? |
|
Definition
surgery:
eyelid: excision +/- reconstruction
conjunctiva: excision
corneal: keratectomy |
|
|
Term
|
Definition
| facial hair contacting the cornea (ex. nasal folds, entropion (eyelid rolled inwards), haired medial caruncle <-- hairs tend to be very fine and well tolerated) |
|
|
Term
|
Definition
| cili arise from openings of meibomian glands and touches the cornea (may be stout or fine, single or multiple, irritating or well tolerated) |
|
|
Term
|
Definition
| aberrant cilia arising from the palpebral conjunctival surface (i.e. the backside of the eyelid, usually very painful! |
|
|
Term
| What are three important considerations with reguards to eyelash disorders? |
|
Definition
regrowth is possible with ALL treatment options
post-op eyelid swelling is significant
eyelid and hair depigmentation |
|
|
Term
| What are the two most definitive treatments for eyelash disorders? |
|
Definition
electroepilation (best for only a few)
cryoepilation (good for many)
plucking is only a short term solution because the cilia will grow back, and may be more coarse and irritating |
|
|
Term
| T/F: ectopic cilia can cause intermittent clinical signs of blepharospasm and epiphora |
|
Definition
TRUE
the cilia can come and go away |
|
|
Term
| What are the three "flavors" of entropion (inversion of the eyelid)? |
|
Definition
anatomic/heritable (eyeball doesn't support the eyelid so the eyelid rolls inwards, usually bilateral)
spastic (pain when the eyelids touch the cornea -->vicious cycle)
cicatircial (ie. scar) (secondary to chronic spastic entropion, eyelid trauma, or surgery) |
|
|
Term
| What are the indications for temporary correction of entropion (ie. eyelid tacking w/ suture or skin staple)? |
|
Definition
spastic entropion (break the cycle)
young growing animals with anatomic/heritable entropion |
|
|
Term
| What are the indications for permanent correction of entropion (ie. holtz-celsus)? |
|
Definition
anatomic/heritable entropion in adult animals
cicatricial entropion |
|
|
Term
| How do you ensure against over-correction of entropion when performing holtz-celsus procedure? |
|
Definition
| apply topical anesthetic to remove any spastic component of the entropion and determine amount of skin to remove soley on anatmical component of disorder |
|
|
Term
| What is the best surgical approach to treat cicatricial ectropion (eyelids droop out)? |
|
Definition
|
|
Term
|
Definition
inflammation of the eyelids
if diffuse often a component of generalized dermatitis |
|
|
Term
| What general treatment principle should be applied to all cases of diffuse blepharitis regardless of etiology? |
|
Definition
systemic administration is best!
topical medications are generally less effective |
|
|
Term
| What are the most common eyelid tumors in dogs? |
|
Definition
| meibomian gland adenoma (ie. benign) |
|
|
Term
| What are the most common eyelid tumors in cats, horses, and cows? |
|
Definition
|
|
Term
| What is the best treatment for eyelid tumors (meibomian gland adenoma in dogs, SCC in cats,horses,cows)? |
|
Definition
| resection with eyelid reconstruction |
|
|
Term
| What physical constraints are associated with full thickness wedge excision treatment of eyelid tumors? |
|
Definition
| can do wedge resction if the tumor encompases less than 1/3 of the eyelid length |
|
|
Term
| T/F: you should only do cryosurgery on eyelid tumors that are suspected to be benign (ie. meibomian adenoma) |
|
Definition
|
|
Term
| What are the three components of the tear film? |
|
Definition
lipid (from meibomian glands)
aqueous (from gland of the third eyelid/orbital lacrimal gland)
mucin (conjunctival goblet cells) |
|
|
Term
| What is the role of the lipid component of the tear film? |
|
Definition
| outermost layer, forms optically smooth surface and prevents evaporation of the aqueous layer. Produced by the meibomian glands |
|
|
Term
| What is the role of the aqueous portion of the tear film? |
|
Definition
| thickest layer, provides nutrition to the cornea and removes metabolic waste, produced by the orbital lacrimal gland and the gland of the third eyelid |
|
|
Term
| What is the role of the mucin layer of the tear film? |
|
Definition
| innermost layer, allows for interface between aqueous layer of tear film and the hydrophobic corneal epithelium, secretory IgA, produced by the corneal goblet cells |
|
|
Term
| Which gland contributes most the the aqueous fraction of the tear film? |
|
Definition
orbital lacrimal gland (60-70%)
30-40% is from gland of the third eyelid |
|
|
Term
| What is the name for a quantitative tear film deficiency? What component of the tear film is affected? |
|
Definition
| Keratoconjunctivitis sicca, decreased aqueous component of the tear film, common in dogs |
|
|
Term
| What component of the tear film is affected in qualitative tear film deficiency? |
|
Definition
| disorder of the lipid/mucin components of the tear film -->instability of the tear film, cannot be quantified because schirmer tear test only measures aqueous component of tears |
|
|
Term
| What are the clinical signs associated with keratoconjunctivitis sicca? |
|
Definition
| blepharospasm, tenacious mucopurulent discharge, conjunctival hyperemia, lackluster corneal surface |
|
|
Term
| What distribution is most common for corneal ulcers secondary to keratoconjunctivitis sicca? |
|
Definition
| suprerior distribution because any moisture will pool in the inferior lids |
|
|
Term
| What is the most common underlying etiology of keratoconjunctivitis sicca? |
|
Definition
immune-mediated, bilateral, lacrimal adenitis
less frequently congenital (disease manifests at a very young age) |
|
|
Term
| What is the most common neurogenic cause for keratoconjunctivitis sicca? What other clinical signs accompany KCS lesions in these patients? |
|
Definition
| Lesion affecting CN 7 (facial) results in loss of neural input to stimulate lacrimal secretions, KCS is is unilateral with ipsilateral dry nose |
|
|
Term
| What is the most common infectious cause of KCS in dogs? In cats? |
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Definition
K9 distemper virus (inflammation of the lacrimal glands)
Feline herpes virus-1 (chronic conjunctivitis) |
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Term
| What drugs cause transient KCS? |
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Definition
topical anesthetics (proparacaine)
Parasympatholytics (atropine, tropicamide)
general anesthesia |
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Term
| Use of what drug can precipitate an idiosyncratic KCS that may not resolve with cessation of the drug? |
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Definition
| Sulfonamides, do a schirmer tear test before starting treatment and continue to monitor, if KCS develops long term treatment is usually required despite cessation of sulfonamide administration |
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Term
| What is the normal value for a schirmer tear test? What is the cut off for KCS? |
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Definition
>15 mm/min
<10 mm/min = KCS |
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Term
| What species may normally have lower schirmer tear test values, why? |
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Definition
| Cats, easily stessed in clinical settings --> high sympathetic tone --> decreased secretions (ie. lacrimation) |
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Term
| What three things are measured by the schirmer tear test? |
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Definition
lacrimal lake (located w/in lower fornyx)
basal tear production over 60 sec
stimulated tear production over 60 sec (strip should be placed laterally, to ensure contact with the cornea --> stimulates tear production) |
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Term
| What is the best way to assess qualitative tear film deficiencies? |
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Definition
Rose Bengal dye --> stains cells that are dead/dying and cells that are inadequately covered with mucus
positive in both qualitative (defficiency in mucin/lipid component of tear film) and quantitative (defficiency in aqueous component) |
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Term
| When should you culture the cornea, what technical considerations are important to ensure accurate sample collection? |
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Definition
| if cornea is ulcerated collect culture from the ulcer bed, do not use a topical anesthetic b/c it inhibits bacterial growth, avoid contacting the eyelids which can contaminate the sample with resident flora |
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Term
| What is the number one cause of bacterial conjunctivitis in dogs? |
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Definition
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Term
| What are the five components to KCS therapy? |
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Definition
1. remove accumulated discharge (before medicating)
2. Provide corneal lubrication (lacrimostimulants are better than lacrimomimetics)
3. Treat occular surface inflammation (topical corticosteroids if no ulcer)
4. Treat secondary bacterial conjunctivitis if present (topical broad spectrum antibiotics)
5. Treat corneal ulceration if present |
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Term
| What is a common lacrimostimulant used in the treatment of KCS? |
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Definition
cyclosporine A (immunosupressant --> inhibits inflammation within the orbital lacrimal gland allowing tissue to regenerate and produce tears, also enhances mucin secretion from conjunctival goblet cells)
must apply topically BID for life |
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Term
| When should you recheck patients with KCS to assess their response to therapy (cyclosporine A)? |
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Definition
| repeat schrimer tear test 1 month after starting cyclosporine A, only effective while given so make sure the patient gets medicated the day of the recheck (and ALL the time) <-- client education point |
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Term
| Other than regeneration of lacrimal gland tissue and stimulation of tear production, what other beneficial effects does cyclosporine A have in patients with KCS? |
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Definition
stabilizes tear film <-- increase mucus secretion from conjunctival goblet cells
decreases corneal neovascularization, pigmentation and scaring with long term use |
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Term
| If cyclosporine A is not completely resolving the KCS what other drug can be added? |
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Definition
| Tacrolimus (also an immune suppressant, extralable so try cyclosporine first) |
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Term
| What surgical treatment can be used if medical management of KCS fails? What are some complications associated with this procedure? |
|
Definition
parotid duct transposition
(always evaluate salivary production first)
saliva is more alkaline than tears, tartar can build up on the corneal surface, if too much salivary flow --> moist dermatitis (may require partial duct ligation) |
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Term
| What is epiphora and what are the two causes of it? |
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Definition
| overflow of tears onto the face caused by excessive lacrimation (secondary to irritation/pain <-- try to identify underlying cause) or nasolacrimal duct obstruction (could be congenital malformation, inflammation, infection, foreign body, or neoplasia) |
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Term
| What is the most important function of the nictitating membrane? |
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Definition
tear distribution and removal of debris
*movement of the third eyelid is passive |
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Term
|
Definition
prolapse of the gland of the third eyelid
occurs in young dogs (less than 1 yr), and protrudes from the posterior aspect of the 3rd eyelid |
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Term
| What is the treatment for cherry eye? |
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Definition
surgical replacement (morgan pocket technique)
*NEVER excise a cherry eye --> KCS |
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Term
| What are some clinical signs associated with conjunctivitis? |
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Definition
| chemosis (edema), hyperemia, ocular discharge, blepharospasm, enlarged conjunctival lymphoid follicles <-- all of these are non-specific signs and can be secondary to episcleral, corneal and intraocular disease |
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Term
| What are the most common infectious eitiologic agents implicated in conjunctivitis? |
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Definition
viral: FHV, k9 distemper (also KCS)
bacterial: chlamydial, mycoplasma
fungal and parasitic |
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Term
| What is a common cause of conjunctivits in cats? |
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Definition
| immune mediated contact hypersenstitivity (esp. with neomycin) |
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Term
| What type of neoplasia is most commonly implicated in conjunctivits? |
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Definition
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Term
| T/F: conjunctivits is usually infectious in origin in cats, and non-infectious in origin in dogs |
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Definition
TRUE
k9: allergic, trauma/irritation
cat: FHV-1, chlamydia |
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Term
| Dogs with allergic conjunctivitis usually have what underlying disease? |
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Definition
| atopy or food allery <-- tx this should clear up allergic conjunctivitis |
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Term
| T/F: dogs with follicular conjunctivitis commonly have underlying atopy or food allergy |
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Definition
FALSE
excessive lymphoid follicle formation on bulbar surface of 3rd eyelid in response to chronic antigen stimulation
tx: rinse eyes and topical steroids |
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Term
| T/F: primary bacterial conjunctivitis is rare in dogs |
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Definition
TRUE
usually secondary to KCS |
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Term
| T/F: cats with FHV suspected conjunctivitis should be isolated from other cats in the house |
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Definition
FALSE
FHV is ubiquitous in the environment so all animals have already been exposed |
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Term
| What type of corneal ulcer is pathognomonic for FHV? |
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Definition
| dendritic ulcers (these form very acutely and often have progressed to geographic ulcers at the time of presentation) |
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Term
| What percentage of cats have latent herpes infection following primary infection? |
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Definition
80%
of these 45% can shed (spontaneous or stress induced, symptomatic or asymptomatic) in their lifetime |
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Term
| How does conjunctivits secondary to recrudenscence of FHV present differently from primary infection? |
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Definition
primary infection --> bilateral conjunctivitis, often complicated with URI
recrudescent infection --> unilateral conjunctivitis, often URI is absent |
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Term
| What is the most sensitive and specific way to diagnose FHV? |
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Definition
PCR from conjunctival swabs
*usually diagnosed based on clincial signs |
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Term
| What is the topical antibiotic of choice when treating infectious conjunctivits in cats? |
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Definition
| terramycin <-- covers chlamydia and mycoplasma |
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Term
| What is an oral anti-viral that can be used to treat patients with frequent episodes of recrudesence? |
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Definition
| L-lysine (alters viral protein synthesis --> inhibits viral replication) |
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Term
| What is the best topical antiviral that cen be used for severe and/or recurrent conjunctivits secondary to FHV? |
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Definition
Idoxuridine (middle efficacy and middle patient tolerability <-- can be very irritating/painful)
must be given 6X a day |
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Term
| What is a potential sequelae to neonatal infection of FHV in kittnes? |
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Definition
| symblepharon (adhesions of eyelid, conjunctiva, and/or cornea secondary to healing of ulcerated surfaces by fusion rather than re-epithelialization) <-- kitten's eyes are closed so the close proximity of ulcerated surfaces predisposes to the formation of symblepharon |
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Term
| T/F: chlamydophila conjunctivitis usually starts unliateral but progressed to be bilateral within a few days |
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Definition
TRUE
can also be distinguished from FHV by the presence of lymphoid follicles with chronicity |
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Term
| What are cytologic features characteristic of chlamydophila conjunctivitis? |
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Definition
intracytoplasmic inclusion bodies within epithelial cells between days 7-14
PCR is also possible with conjunctival swabs |
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