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59 Cards in this Set
- Front
- Back
What are the 3 layers of the eye?
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Outer, Fibrous
Middle, Vascular Inner, Nervous |
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What are the 3 components to the outer, fibrous layer and where are they located?
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Cornea (anterior)
Sclera (posterior) Limbus (junction of the cornea and sclera) |
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What is the function of the outer fibrous layer?
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Protection, transmission and refraction of light
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What are the 3 components to the middle, vascular layer and where are they located?
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Iris (most anterior)
Ciliary body (posterior to iris) Choroid (most posterior, under retina) |
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What are the 2 components of the anterior uvea?
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Iris
Ciliary Body |
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What is the function of the ciliary body?
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Produces the aqueous
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What is the function of the middle, vascular layer?
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Nutrition, immunity and accomodation
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What is accomodation?
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The ability to focus at a distance or up close
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What are the components of the inner, nervous layer?
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The retina
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What is the function of the inner, nervous layer?
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Responsible for turning light into an electrical nervous impulse
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What are the 2 parts of the conjunctiva?
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Palpebral
Bulbar |
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What is the fornix?
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Where the palpebral conjunctiva reflects onto the bulbar conjunctiva
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Where is the palpebral conjunctiva?
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It lines the inside of the eyelids and the 3rd eyelid
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Where is the bulbar conjunctiva?
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It covers the anterior aspect of the sclera
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What two structures make up the optical media?
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Cornea
Lens |
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What is the optical media?
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The structures that allow light to enter the eye and refract light
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What is the most powerful refractive element in the eye?
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The cornea...
because it has an air interface |
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Where is the anterior chamber located?
What is inside of it? |
Between the posterior aspect of the cornea and the anterior aspect of the iris and lens
The aqueous |
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What is the significance of the iridocorneal angle?
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Where the aqueous drains from the eye; located at the anterior base of the iris and the peripheral, posterior aspect of the cornea
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Where is the posterior chamber located?
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Between the posterior aspect of the iris and the anterior aspect of the lens
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Where is the Vitreous cavity?
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located between the posterior aspect of the lens and the retina
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Where is the tapetum?
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Lies immediately under the retina, part of the choroid
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What to the fibers of the optic nerve leave through?
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The scleral lamina cribosa (small holes in the sclera)
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What are the 4 clinically important layers of the adnexa?
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1. Skin
2. Orbicularis oculi m. 3. Meibomian (tarsal) gland 4. Palpebral conjunctiva |
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What is the function and significance of the orbicularis oculi muscle?
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function: responsible for closing eyelids/responsible for blepharospasm
significance: primary holding layer for eyelid sx |
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What do the Meibomian glands produce?
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The lipid layer of the tear film
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What does the palpebral conjunctiva contain?
What else is relevant about the palpebral conjunctiva? |
Goblet cells that produce the mucous layer of the tear film
Source of tissue for grafts and flaps during surgical procedures |
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What is the function and innervation of the Levator palpebrae superioris muscle?
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Opens upper eyelid
innervated by CN III |
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Muller's Muscle
-type of muscle -function -innervation |
-smooth muscle
-function is to maintain a consistent palpebral fissure opening -sympathetic innervation |
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Which muscle is responsible for ptosis in Horner's syndrome
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Muller's muscle
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4 Functions of the adnexa?
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1. General protection
2. Spread tear film and prevent evaporation 3. Produces lipid and mucous portions of tear film 4. Tear drainage |
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4 General signs of eyelid disease?
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Redness
Swelling Blepharospasm Secondary effects --> corneal changes, epiphora |
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What are the 4 layers of the cornea?
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1. Epithelium (5-10 cells thick)
2. Stroma 3. Descemet's Membrane 4. Endothlium |
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Which layer of the cornea is highly hydrophobic?
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Epithelium
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Which layer of the cornea is highly hydrophilic?
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Stroma
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Which layer of the cornea will take up fluorescein dye?
Which do not? |
Stroma will take up dye
Epithelium and Descemet's Membrane will not |
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Which layers of the cornea are involved in keeping the cornea dehydrated?
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Epithelium
Endothelium (has Na/K pump which can remove fluid from the stroma via active transport) |
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What are the 2 source of nutrition for the cornea?
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1. tears (anterior)
2. aqueous (posterior) |
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Where is the Na/K pump found in the cornea?
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Corneal endothelium
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5 factors involved in corneal transparency?
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1. avascularity
2. relative dehydration 3. orderly arrangement of stromal collagen fibrils 4. lack of pigment 5. non-keratinzed epithelium |
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What are 3 functions of the cornea?
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1. Transmission of light
2. Refraction of light 3. Part of the outer fibrous layer --> protection |
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Name 2 organisms that can infect a healthy cornea to cause an ulcer
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Herpesvirus
Morixella bovis |
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What nerve innervates the stroma, and where is it innervated?
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CN V
The anterior aspect of the stroma is innervated, while the posterior aspect is not |
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Corneal edema is a _______ (specific/nonspecific) sign and suggests a problem in one of these two layers _________ or _________
If the edema is diffuse, that suggests the defect is in the ______ while if the edema is sectional, that suggests the defect is in the __________ |
Corneal edema is a nonspecific sign and suggests a problem in the epithelium or endothelium
If the edema is diffuse, that suggests the defect is in the endothelium while if the edema is sectional, that suggests the defect is in the epithelium |
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What are the epithelial and endothelial components of the blood-aqueous barrier?
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Epithelial: junctions between inner, non-pigmented epithelium of the ciliary body
Endothelial: non-fenestrated capillaries of the iridal vessels |
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Iris Sphincter muscle
-type of muscle -what nerve innervates it? -what type of innervation -how oriented? |
-smooth muscle
-CN III -parasymapthetic -circumferential |
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Iris dilator muscle
-type of muscle -type of innervation -how oriented? |
-smooth muscle
-sympathetic innervation -radially |
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Entropion
-what is it and where -common breeds -tx |
-Rolling in of the eyelid margin, usually at the lateral aspect of the lower lid
-mid to large breeds (retrievers, shar peis) -tx: <1 year: eye lube + tacking if severe; >1 year: Hotz-Celsus "smile" |
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Ectropion
-what is it and where -common breeds -tx |
-loss of contact of the lower eyelid margin, usually at the central portion
-cockers, bloodhounds, St. Bernard's, Mastiffs, other giant breeds -tx: usually none, topical lube |
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Distichiasis
-what is it -common breeds -tx |
-A cilium emerges from the opening of the ducts of the Meibomian gland
-cocker spaniels, Golden retrievers -manually epilate to see if it's causing the problem; after regrowth can use cryo or electroepilation to remove |
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Ectopic cilia
-what is it -tx |
-cilia that emerge through the palpebral conjunctiva
-excision with cryotherapy |
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Trichiasis
-what is it -signs -breeds -tx |
-hairs in contact with the ocular surface (usually medial canthus and nasal folds)
-wicks tears onto the surface of the face -brachycephalic breeds -usually nothing, can cryo off |
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Where are the 3 layers of the tear film produced?
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aqueous: produced by lacrimal gland and the gland of the 3rd eyelid
lipid: produced by the meibomian gland mucous: produced by goblet cells in the conjunctiva (fornix) |
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Function of aqueous layer of tears?
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nutrition to cornea + immunity
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Function of the lipid layer of tears?
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allows for even spreading and prevents evaporation
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Function of the mucous layer of tears?
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allows for the aqueous portion to adhere to the hydrophobic corneal epithelium
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Characteristics of an uncomplicated corneal ulcer
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-involves only corneal epithelium (no stromal loss)
-heals within 7-10 days (often sooner) -no change in stromal character -no extensive corneal vascularization |
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Characteristics of a complicated corneal ulcer
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-increasing depth (non-specific)
-presence of a stromal infiltrate (specific) -change in stromal character (melting) -corneal vascularization (non-specific) -hasn't healed in 7-10 days |
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What are the most common causes of a complicated corneal ulcer?
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-infection (bacterial/fungal/viral)
-foreign bodies -exposure -persistent corneal ulceration syndrome -ectopic cilia/entropion |