Term
| Three Layers of the Eyeball |
|
Definition
Fibrous Tunic (Outermost, Sclera and Cornea)
Vascular Tunic (Middle, Iris, cilliary body, choroid)
Nervous Tunic (Innermost, retina) |
|
|
Term
|
Definition
white of the eye
caudal part of the fibrous tunic
junction between cornea and sclera is called the limbus
Function - shape and protection |
|
|
Term
|
Definition
transparent window
rostral part of the eye
covers iris and anterior chamber
nonvascular
Function - pain reception, admits light into interior of the eye |
|
|
Term
|
Definition
Transparency of the cornea is controlled by the amount of water in the eye
corneal edema is a result of too much water
corneal opacity is a result of too little water |
|
|
Term
|
Definition
Middle layer of the eyeball
also known as the uvea
contains blood vessels that supply nutrition to retina
smooth muscle controls shape of lens and size of pupil |
|
|
Term
|
Definition
posterior part of the vascular tunic
thin, dark membrane between sclera and retina
forms highly reflective area in rear of the eye called tapetum lucidum
highly vascular, supplies nutrition to the retina |
|
|
Term
| Choroid (Tapetum Lucidum) |
|
Definition
highly reflective area in the back of the eye
aids in low light/dim vision
birds, pigs and humans don't have one |
|
|
Term
|
Definition
In birds and some reptiles
Comb-like structure of blood vessels in the choroid, non-sensory, pigmeneted
Function - nourishes retina, controls pH of vitreous body, pigmented to protect from UV rays |
|
|
Term
| Vascular Tunic (Ciliary Body) |
|
Definition
| Thickest portion of the vascular tunic between the choroid and iris |
|
|
Term
| Vascular Tunic (Ciliary Body Processes) |
|
Definition
suspensory/zonular ligament - attaches lens to ciliary body, holds lens in position, allows shape of lens to change due to actions of ciliary muscles
Accomodation - process of altering the shape of the lens |
|
|
Term
|
Definition
| colored doughnut shape part of the eye surrounding the pupil that contains two layers of muscles and increases or decreases the size of the pupil by controlling amount of light that enters the eye |
|
|
Term
| Corpora nigra, granula iridica |
|
Definition
corpora nigra - horses
granula iridica - ruminants
protects eyes from direct sunlight |
|
|
Term
|
Definition
| Central opening of the iris that lets light into the eye |
|
|
Term
|
Definition
| variations in iris color, an excess or lack of pigmentation |
|
|
Term
|
Definition
| variations in color of different regions of the iris of the same eye |
|
|
Term
|
Definition
| variations of iris color between two eyes |
|
|
Term
|
Definition
inner coat of the eye
functions in image formation
Fundus - general term for the portion of the organ opposite its opening |
|
|
Term
|
Definition
| Lines only the caudal part of the eye |
|
|
Term
|
Definition
| ending of retina at ciliary body, has scalloped border, marks transition from the simple non-photosensitive area of the retina to the complex, a multilayered photosensitive region |
|
|
Term
|
Definition
Light-sensitive first layer of the retina
dendrites of photoreceptors (cones and rods)
domestic animals have many rods but fewer cones |
|
|
Term
|
Definition
| sensitive to dim light (night vision) and shapes |
|
|
Term
|
Definition
sensitive to color and sharpness
densely packed in fovea centralis, located in macula lutea (yellow area in caudal part of retina)
humans, primates and fish have a fovea centralis, domestic animals do not |
|
|
Term
|
Definition
Dogs, cats and horses (some color vision)
Cattle and sheep (probably color blind)
Birds (highly developed color sense, fine visual discrimination) |
|
|
Term
|
Definition
also known as the blind spot of the eye (no rods or cones)
area on the retina where axons from ganglionic neurons leave eye in optic nerve |
|
|
Term
|
Definition
transparent biconvex structure
located caudal to the iris
part of refracting mechanism of the eye |
|
|
Term
|
Definition
| the bending of light to a center point of focus |
|
|
Term
| Interior of the Eye (Anterior Cavity) |
|
Definition
Anterior Chamber - between the cornea and the iris
Posterior Chamber - between the iris and lens |
|
|
Term
|
Definition
watery consistency
fills anterior cavity
secreted by ciliary processes into posterior chamber |
|
|
Term
|
Definition
Flows through pupil into anterior chamber
drains at periphery of anterior chamber into blood
maintains intraocular pressure |
|
|
Term
| Interior of the Eye (Posterior Cavity) |
|
Definition
| between the lens and the retina, filled with vitreous humor |
|
|
Term
|
Definition
jelly-like substance
maintains shape of globe
holds retina in place |
|
|
Term
| Accessory Structures (Adnexa) |
|
Definition
| appendages of the eye (eyelids, conjunctiva, glands of the eye and lacrimal apparatus) |
|
|
Term
|
Definition
eyelids
two moveable folds protecting rostral surface of the eyeball |
|
|
Term
|
Definition
|
|
Term
|
Definition
Protection from dust, pollen, etc
Blink reflex - aids in protection, involuntary
If absent - may be indication of cranial nerve 7 dysfunction
blink reflex disappears under surgical plane of anesthesia
distribute tears over cornea |
|
|
Term
| Lateral and Medial Canthi |
|
Definition
| angles where upper and lower eyelids meet |
|
|
Term
|
Definition
| triangular prominence in medial canthus |
|
|
Term
|
Definition
|
|
Term
|
Definition
eyelashes
Dog - present on upper, absent on lower
Cat - poorly developed, no true eyelashes
Equine - many upper lid lashes, few lower |
|
|
Term
| Meibomian Gland (Tarsal Gland) |
|
Definition
| exocrine gland associated with each lash, secretes an oil that is a component of tears |
|
|
Term
|
Definition
MM lining the eyelid and eyeball
produces mucus - inner layer of tears
has antibiotic substances that help protect the eye |
|
|
Term
| Palpebral and Bulbar Conjunctiva |
|
Definition
palpebral lines inner eyelid
blubar is the layer of conjunctiva that covers a portion of the sclera under the eyelid |
|
|
Term
|
Definition
composed of conjunctiva reinforced by cartilage and the gland of the third eyelid
located between eyelid, medial canthus and eyeball
also called the nictitating membrane
retraction of the eyeball causes third eyelid to move across and protect the eyeball |
|
|
Term
|
Definition
structures that manufacture and drain away tears
tears - liquid film that moistens and protects the eye |
|
|
Term
| Three Components of Lacrimal Apparatus |
|
Definition
inner mucus layer
water portion - middle layer
outer oil layer - decreases evaporation and keeps tears in the eye |
|
|
Term
|
Definition
located on dorsolateral aspect of the eyeball
produces 50% of watery portion of tears from ducts onto the surface of the eyeball |
|
|
Term
| Gland of the Third Eyelid |
|
Definition
| produces other 50% of watery portion of the tears |
|
|
Term
|
Definition
| First holding site for tears, these are openings of the lacrimal canaliculi on upper and lower eyelids near the medial canthus |
|
|
Term
|
Definition
| small canals from the lacrimal puncta to the lacrimal sac |
|
|
Term
|
Definition
| second holding site for tears, beginning of nasolacrimal duct |
|
|
Term
|
Definition
| duct extending from the lacrimal sac to the nasal cavity, opens into nasal cavity |
|
|
Term
|
Definition
| overflow of tears over lower eyelid onto fur |
|
|
Term
|
Definition
Pupillary sphincter
Pupillary dilator
Ciliary Muscles - deal with lens shape (accommodation) |
|
|
Term
|
Definition
these move the eyeball and are located behind eye
recti - dorsal, medial, lateral, ventral
oblique - dorsal and ventral |
|
|
Term
|
Definition
surrounds eyelids
closes eyelids |
|
|
Term
| Gross Examination of the Eye |
|
Definition
Check gross appearance of face and of eyes
pain/discomfort
discharge
lesions - unilateral vs. bilateral
bilateral lesions indicate a systemic disease while unilateral lesions often indicate a local disease |
|
|
Term
|
Definition
Lacrimation - normal tears
Serous discharge - clear, watery (allergies)
Mucoid discharge - mucus
Purulent Discharge - contains pus
Mucopurulent - both mucoid and purulent characteristics |
|
|
Term
|
Definition
a smaller than normal eye
ex - collie eye, phtisis bulbi (dry, shrunken eye) |
|
|
Term
|
Definition
A larger than normal eye
ex - chronic glaucoma |
|
|
Term
|
Definition
eye is sunken back into the globe
occurs due to microphthalmia, abnormal retraction of extrinsic eye muscles, loss of adipose tissue, dehydration, pain secondary to anterior uveitis, conjunctivitis, etc. |
|
|
Term
|
Definition
Abnormal protrusion of the eye
occurs due to space occupying lesions behind the eye, deformity of the orbit, brachycephalic breeds |
|
|
Term
|
Definition
| the eye is normal in size but appears to be exophthalmic |
|
|
Term
|
Definition
deviation of the eye
Esotropia - inward deviation
Exotropia - lateral deviation |
|
|
Term
|
Definition
| an automatic response to a stimulus |
|
|
Term
|
Definition
| a change in the environment that can be detected by neurological receptors |
|
|
Term
|
Definition
| observation of an animals response to an unexpected image placed suddenly in front of the eye |
|
|
Term
|
Definition
| tests the ability of the animal to follow an object with its eyes, use cotton ball |
|
|
Term
|
Definition
| the animal navigates through a maze or series of barriers |
|
|
Term
|
Definition
| a test to determine whether there are lesions in the neurological portion of the eye, performed by directing light into one of the eyes in a darkened room, use of pen light |
|
|
Term
| Positive direct and indirect (consensual) reflex |
|
Definition
pupil in the same eye will constrict for positive direct, for positive indirect the pupil in the opposite eye will constrict
Normal result - both pos direct and pois indirect response |
|
|
Term
|
Definition
| used to examine the fundus of the eye, one pupil is dilated with a mydriatic, one looks directly into the eye through the lens in the ophthalmoscope, magnified 15-18 times upright |
|
|
Term
|
Definition
| used to examine the fundus of the eye, performed by using a hand lens and a light source, you see a reversed image magnified 3-5 times |
|
|
Term
| Bacteriological and Mycotic Examination |
|
Definition
| culture sites - anterior edge of third eyelid, inner surface of the eyelid, directly from the cornea |
|
|
Term
|
Definition
measures tear formation
a sterile strip of paper is placed between the lower eyelid and cornea, measures amount of moisture in the eye, leave for 60 seconds, normal is 17-22mm, only concerned with underproduction |
|
|
Term
| Fluorescein Stain of the Cornea |
|
Definition
| Evaluates outer surface of the cornea, abrasions and ulcers will take up stain, used to also measure patency of nasolacrimal duct, apply stain, rinse, check for ulcers |
|
|
Term
| Nasolacrimal duct irrigation |
|
Definition
| used to determine the cause of epiphora, used when there is mucopurulent discharge, check for failure of passage of fluorescein stain |
|
|
Term
|
Definition
| measures the amount of flattening of the cornea when a weight is placed on the surface of the cornea, provides measurement for intraocular pressure, use of tonometer |
|
|
Term
| Indications for Applanation Tonometry |
|
Definition
Red or painful eye
Breeds that are predisposed to glaucoma
checking the opposite eye in an animal that has glaucoma, following up in an animal that has medically controlled glaucoma |
|
|
Term
|
Definition
abnormal flow of tears over the face
causes - superficial irritation causing excessive tear production, obstruction of drainage system |
|
|
Term
| Breed Predisposition to Epiphora |
|
Definition
breeds that have excess hair around nasal canthus (poodles, lhasas, maltese)
breeds that have excessive nasal folds which obstruct nasolacrimal duct (brachycephalics) |
|
|
Term
|
Definition
| growth of the eyelash towards the surface of the eye, may be acquired or congenital, tx = remove follicle, remove skin folds around eyes(hounds, chows), cryotherapy or electrocautery |
|
|
Term
|
Definition
| there are two rows of eyelashes with one row rubbing on the cornea, congenital, tx = same as trichiasis |
|
|
Term
|
Definition
| there is more than one eyelash growing out of the follicle, congenital, same tx as trichiasis |
|
|
Term
|
Definition
most common eyelid growth in older dogs
a benign tumor of the meibomian gland
may cause local irritation
tx - cryosurgery |
|
|
Term
|
Definition
| chronic, firm, nonpainful enlargement of a meibomian gland, caused by an obstruction of its duct, tx = warm compress, incising growth and curettage, topical tx 7-10 days post |
|
|
Term
|
Definition
| a very malignant tumor arising from epithelial tissue, normally occurs on nose, lips, eyelids and ears, common in non-pigmented animals (especially those that sun bathe) |
|
|
Term
|
Definition
prolapse of the nictitating membrane gland
occurs due to congenital loss of connective tissues, superficial irritation stimulates eye to retract back into orbit, inflammation hypertrophy of the gland occurs once it is prolapsed |
|
|
Term
| Cherry Eye Breed Disposition |
|
Definition
| beagles, pekingnese, cocker spaniel, english bulldogs |
|
|
Term
|
Definition
| replacement of the gland into its proper position and suturing in place, removal of gland will predispose animal to KCS, can replace with transposition of salivary gland |
|
|
Term
|
Definition
| The eyelid and eyelashes are inverted, can be congenital or acquired |
|
|
Term
|
Definition
| Can be a result of a blepharospasm. causes of blepharospasm include corneal injuries such as an eyelash problem or a foreign body or conjunctivitis |
|
|
Term
|
Definition
| born with entropion, common breeds include chows, share peis, bulldogs, st. bernard |
|
|
Term
|
Definition
| tx the cause (foreign body), surgery if congenital |
|
|
Term
|
Definition
| lower eyelid is everted, commonly occurs in bassets and blood hounds |
|
|
Term
|
Definition
| congenital, loose-skinned dogs, fatigue of some facial muscles in hunting dogs, paralysis due to damage of facial nerve, scar tissue, overcorrection of entropion |
|
|
Term
|
Definition
if due to paralysis - if temporary it will correct itself, if permanent the affected eye may have to be removed
if congenital - sx |
|
|
Term
| Mydriasis, Miosis, Anisocoria |
|
Definition
Mydriasis - dilated pupil
Miosis - constricted pupil
Anisocoria - difference in the size of the pupils |
|
|
Term
|
Definition
| blood in the anterior chamber when vessels are damaged, can be acute or chronic |
|
|
Term
|
Definition
| Trauma (perforating wounds, blow to the head, choking the animal), infections, neoplasia, chronic glaucoma/systemic hypertension, coagulation abnormalities |
|
|
Term
|
Definition
pus in the anterior chamber
causes - infections, anterior uveitis, keratitis |
|
|
Term
|
Definition
| Prolapse of the globe, emergency |
|
|
Term
| Prognostic Signs of Proptosis |
|
Definition
injury to the extrinsic eye muscles (anymore than three torn will result in probable removal of the eye)
hyphema - usually severe damage to the ciliary body
prognosis for vision is guarded at 20% which will regain functional vision |
|
|
Term
| Other Prognostic Signs of Proptosis |
|
Definition
Pupil size. a pinpoint pupil is a normal response to pain, a dilated pupil indicates that the sympathetic innervation is intact
Near normal pupil is bad prognosis |
|
|
Term
| What are some good signs of Proptosis |
|
Definition
No hyphema
No more than 2 extrinsic muscles injured
a pinpoint pupil
tx proptosis with replacement of the eye asap! |
|
|
Term
|
Definition
inflammation of the conjunctiva
C/S - discharge, hyphema, chemosis (conjunctival swelling), pain |
|
|
Term
| Bacterial Causes of Conjunctivitis |
|
Definition
a pathogenic bacteria must be isolated, chlamydophilia in cats and sheep, mycoplasma in cats, staphylococcus in dogs
Tx - tetracyclines, erythromycin, azithromycin |
|
|
Term
| Viral Causes of Conjunctivitis |
|
Definition
In all species of animals
cats - herpesvirus 1, calcivirus
dogs - canine distemper virus |
|
|
Term
| Mycotic Causes of Conjunctivitis |
|
Definition
often associated with corneal lesion
Rickettsiae
External parasites (usually due to self-trauma from associated pruritus, can be face flies, demodectic mange) |
|
|
Term
| Allergic Causes of Conjunctivitis |
|
Definition
| increased incidence in hunting dogs due to face being close to ground, continued use of topical drugs in the tx of conjunctivitis |
|
|
Term
|
Definition
| topical and systemic drugs depending on the cause |
|
|
Term
|
Definition
| chornic disease involving the cornea and conjunctiva, occurs due to inadequate tear production, also known as dry eye or xerophthalmia |
|
|
Term
|
Definition
certain systemic diseases
congenital
trauma
atrophy of lacrimal glands
medications such as certain sulfa drugs
surgical removal of the gland of the third eyelid
idiopathic |
|
|
Term
|
Definition
pain
decreased tear film
mucous production
excessive ocular discharge
corneal ulceration
conjunctivitis
keratinized cornea |
|
|
Term
|
Definition
| Schirmer Tear Test - remember 17-22mm normal range/60 secs |
|
|
Term
|
Definition
Medical - cyclosporine (stimulates tear production), artificial tears
Surgery - transposition of the parotid salivary duct |
|
|
Term
|
Definition
inflammation of the iris, ciliary body, and choroid
anterior uveitis - inflammation of the iris and ciliary body
posterior uveitis - inflammation of the choroid |
|
|
Term
| Clinical Signs of Uveitis |
|
Definition
| inflammation due to increased blood supply, hypopyon due to the migration of white blood cells to the sight, blepharospasm due to increased pain/sensitvity, epiphora |
|
|
Term
|
Definition
trauma
introduction of infection by penetrating wounds
spread of inflammation from other surrounding structures
secondary to disease
hypersensitivity reactions
idiopathic |
|
|
Term
|
Definition
| topical anti-inflammatory therapy including - corticosteroids, NSAIDS, antimicrobials, mydriatics to promote pupil mobility and decrease ocular pain |
|
|
Term
|
Definition
| iris blocks the drainage of aqueous humor which may lead to glaucoma |
|
|
Term
|
Definition
| iris adheres to the lens, blocking the drainage of aqueous humor which may lead to glaucoma |
|
|
Term
|
Definition
may be due to chronic inflammation (uveitis) or secondary to trauma
tx - treat the cause |
|
|
Term
|
Definition
| a defect or break in the epithelial surface of the cornea (aka ulcerative keratitis) |
|
|
Term
|
Definition
Superficial
Deep
Descemetocele |
|
|
Term
|
Definition
| does not involve stroma (superficial) and heals within 7 days. classified as acute and superficial |
|
|
Term
|
Definition
| involves stroma (deeper) and persists longer than 7 days. classified as deep or chronic |
|
|
Term
| Causes of Ulcers (Mechanical) |
|
Definition
| abrasions, eyelash diseases, foreign bodies, prolonged exposure of the cornea |
|
|
Term
| Causes of Ulcers (Infections) |
|
Definition
| bacterial, viral, mycoplasma |
|
|
Term
| Causes of Ulcers (Metabolic) |
|
Definition
|
|
Term
| Causes of Ulcers (Neurotropic) |
|
Definition
|
|
Term
|
Definition
pain
ocular discharge
corneal changes (loss of transparency, vascularization, crater formation) |
|
|
Term
|
Definition
|
|
Term
|
Definition
remove underlying cause
medical - TAB ophthalmic ointment
surgical - protection of the cornea (third eyelid flap, conjunctival flap, tarsorrhaphy) |
|
|
Term
|
Definition
| type of keratitis (inflammation of the cornea), deposition of pigment on the surface of the eye, usually bilateral |
|
|
Term
|
Definition
UV light may cause degeneration of connective tissue of the cornea
Breed predisposition - german shepherd and huskies |
|
|
Term
|
Definition
| There is no cure, if left untreated it may lead to blindness. Tx may slow down progression of dz |
|
|
Term
|
Definition
medications (usually topical) include corticosteroids, cyclosporine
surgery - superficial keratotomy
beta radiation |
|
|
Term
|
Definition
| increased ocular pressure that results from the altered flow of aqueous humor |
|
|
Term
|
Definition
the narrowing of the iridocorneal angle which obstructs the outflow of aqueous humor.
it can be primary (congenital)
it can be secondary to a previously existing eye disease (luxated lens, anterior or posterior synechia resulting from anterior uveitis or post trauma) |
|
|
Term
|
Definition
Pain
Cloudy Cornea
Dilated pupil
Blindness |
|
|
Term
|
Definition
Mannitol
Miotic drugs (open iridocorneal angle and inhibits secretion of aqueous humor)
adrenergenic drugs (decreases the aqueous humor by decreasing cappilary flow) |
|
|
Term
| How is Glaucoma Tx (Surgical) |
|
Definition
if it is secondary treat the cause
destruction of ciliary body
open existing drainage channels
enucleation |
|
|
Term
|
Definition
| opacity of the lens or its capsule |
|
|
Term
|
Definition
can be congenital or hereditary
metabolic (diabetes mellitus)
iatrogenic (corticosteroids)
age (most common) |
|
|
Term
| Treatment of Cataracts (Surgical Removal) |
|
Definition
| Phacoemulsification - shattering the lens with high frequency ultrasonic waves with removal of debris via irrigation and aspiration |
|
|
Term
| Clinical Signs of Cataracts |
|
Definition
| opacity of lens and a decrease in vision function |
|
|
Term
|
Definition
Results from the hardening of the lens with age (>6 years) due to build up of lens fibers
different than a cataract but looks the same
nuclear sclerosis is transparent where a cataract has opacities
Cataract - tapetum not visible
Nuclear Sclerosis - tapetum visible |
|
|
Term
|
Definition
can be focal, multifocal, or complete
focal or minor detachment may lead to detectable vision loss
complete detachment leads to blindness |
|
|
Term
| Causes of Retinal Detachment |
|
Definition
Trauma
Predisposition (brachycephalics)
accumulation fo fluid behind the retina
infectious disease |
|
|
Term
| Clinical Signs of Retinal Detachment |
|
Definition
mydriasis, lack of PLR, loss of vision
dx though ophthalmic exam or ultrasonography |
|
|
Term
|
Definition
|
|
