The Eye Flashcards
What are the three layers of the eye?
1) Sclera
2) Choroid
3) Retina
What is the sclera?
outer white layer
maintains shape
Muscles attached control movement
What is the choroid?
Middle layer
Blood vessels
What is the retina?
innermost layer
Rods
Cones
Bipolar cells
What is the cornea?
Clear circular area in the sclera where light enters the eye
What is the pupil?
Circular opening in front of the choroid
What is the iris?
Colored smooth muscle surrounding the pupil which adjusts the opening according to the brightness of the light
What is the lens?
Located behind the pupil, between the anterior and posterior chambers
In a constant state of adjustment as it becomes thinner or thicker to accomodate the detailed input it receives
What is aqueous humor?
transparent, watery fluid similar to plasma but containg low protein concentrations
Fill both anterior and the posterior chambers of the eye
Formed by the ciliary body, enters the posterior chamber, bathes the lens, and circulates through the pupil to gain access to the anterior chamber
What is vitreous humor?
Located in the space between the lens and retina - aka vitreous chamber
What are the rods and cones?
synapse with bipolar cells which thensynapse with ganglion cells whose axons form the optic nerve
What do rods do?
night vision
What do cones do?
Color blindness
What is the orbit?
compartment that is closed medially, laterally, and posteriorly
What is proptosis?
disease of the orbit that increases the orbital contents and displaces the eye forward
What are examples of proptosis diseases?
Graves disease
Enlargement of the lacrimal gland from inflammatio or neoplasm
What is the eyelid?
Composed of skin externally and mucosa (conjunctiva) on teh surface apposed to the eye
Generates critical components of the tear film
What is the palpebral conjunctiva?
Lines the interior of the eyelid
What is the bulbar conjunctiva?
Covers the surface of the eye
What is the limbus?
Intersection between the clear and the cornea
What does bacterial and viral conjunctivitis cause?
Redness and itching
Heals without sequelae
What does Chlamydia trachomatis cause?
Significant conjunctival scarring
What is a pinguecula?
Yellowish patch or bump on the conjunctiva near the cornea
Submucosal elevations on the conjunctiva from actinic damage (UV)
What is Pterygium?
Triangular shaped growth of fleshy tissue on the white of the eye that eventually extends over the cornea
Change in the normal tissue that results in a deposit of protein, fat, or calcium
Can develop from a pinguecula
What does the corneal stroma lack?
Blood vessels and lymphatics
It is immunoprivileged
What are keratitis and ulcers caused by?
Bacterial, fungal, and viral (especially herpes simplex and herpes zoster) and protozoan (acanthamoeba) infections
What does corneal neovascularization cause?
Risk of corneal graft rejection
What is myopia?
EYe is too long for its refractive power
Light is focused in front
What is hyperopia?
Eye is too short and light is focused behind
What are the types of corneal degeneration?
Non-hereditary unilateral and bilateral
What are corneal dystrophies?
Bilateral and hereditary
What is keratoconus?
Progressive thinning and ectasia of the cornea without evidence of inflammation or vascularization leading to conical cornea which is bilateral
What is keratoconus associated with?
Down syndrome
Marfan syndrome
Atopic disorders
What is Fuchs Endothelial Dystrophy?
Loss of endothelial cells causing edema and thickening within cornea
Common indication for corneal transplantation
What are the clinical manifestations of Fuchs endothelial dystrophy?
Stroma edema
Bulbous keratopathy
What is psudophakic bulbous keratopathy?
Endothelial cells decrease following cataract surgery
What is the anterior chamber?
Bound anteriogly by the cornea, laterally by the trabecular meshwork and posteriorly by the iris
What are cataracts?
Occur in anterior segment
Lenticular opacities that may be congenital or acquired
What are the causes of cataracts?
Systemic disease = galactose is, diabetes Mellitus
Drugs = corticosteroids
Radiation
Trauma
Age-related = opacification of the lens nucleus (nuclear sclerosis)
What is glaucoma?
Collection of diseases characterized by distinctive changes in the visual field and in the cup of the optic nerve
Associated with elevated intraocular pressure from aqueous humor not draining properly
How does aqueous humor drain?
Posterior chamber (ciliary body production —> Pupil —> Anterior chamber —> trabecular meshwork —> Schlemm’s canal
What is open-angle glaucoma?
Drainage angle formed by the cornea and iris remains open, but the trabecular meshwork is partially blocked
What is angle-closure glaucoma?
The iris bulges forward to narrow or block the drainage angle formed by the cornea and iris
What is the primary cause of open-angle glaucoma?
Genetics
What are the secondary causes of open-angle glaucoma?
Ocular vascular malformations
Trauma
What is the primary cause of angle-closure glaucoma?
Hyperopia
What are the secondary causes of angle-closure glaucoma?
Retinal ischemia
Tumors
What is ophthalmitis?
Intraocular inflammation causes by vessels in the ciliary body and iris becoming leaky and allowing cells and exudate to accumulate in the anterior chamber
What is anterior synechiae?
Inflammatory exudate in the anterior chamber causing adhesions between the iris and the trabecular meshwork or cornea
What is posterior synechiae?
Inflammatory exudate in the anterior chamber causing adhesions between the iris and anterior surface of the lens
What is endophthalmitis?
Inflammation within the vitreous humor
What is panophthalmitis?
Inflammation within the eye that involves the retina, choroid, and sclera and extends into the orbit
What is caused by anterior synechiae?
increased intraocular pressure and optic nerve damage
What is caused by posterior synechiae?
Anterior subscapular cataract
