Ch 29- The eye Flashcards
layers of the eye
- outer layer= sclera
- choroid= middle layer
- retina = innermost layer
sclear
- outer white layer
- maintains shape
- muscles attached for movement control
choroid
- middle layer
- blood vessels
retina
- inner most layer
- light sensitive tissue lining back of eye
- made up of ten layers
- rods, cones, bipolar cells
cornea
- clear circular area in sclera where light enters the eye
- no blood vessels or lymphatics- immunoprivileged
pupil
circular opening in front of choroid
iris
- colored smooth muscle
- surrounds pupil
- adjusts the opening according to brightness of light
lens
- located behind pupil ad between anterior/ posterior chambers
- is in a constant state of adjustment
- thinner or thicker to accommodate input
aqueous humor
- transparent, watery fluid similar to plasma
- low protein concentration
- fills anterior and posterior chambers of teh eye
vitreous humor
- located in space between lens and retina
rods
- night vision
- found in retina
cones
- color vision
- found in retina
proptosis
- displacement of eye forward
- i.e. graves disease, enlargement of lacrimal glands from inflammation or neoplasm
eyelid
- skin found externally
- conjunctiva- mucosa found on surface apposed to eye
- generate critical components of tear film
chalazion
- sebaceous gland becomes obstructed
- sebum leaks out which is rich in lipids
- collects under skin -> chalazion
palpebral conjunctiva
lines interior of eyelid
bulbar conjunctiva
covers surface of eye
limbus
intersection between sclera and cornea
what types of conjuctivitis cause conjunctival scarring?
chlamydia infections
pinguencula
- submucosal elevation on conjunctiva from UV damage
- yellow patch or bump on conjunctiva
- occurs near cornea
- deposits of proteins, fat or calcium
pterygium
- traingular shaped growth of fleshy tissue on white of eye that extends over cornea
- often develops from pinguecula
myosis
- eye is too long
- light gets focused in front of retina
- short sighted
hyperopia
- eye is too short
- light rays get focused behind retina
- long sighted
keratitis and ulcers of cornea
- bacterial, fungal or viral causes
- viral- HSV or VZV
- protozoal- acanthamoeba
corneal degeneration
- non-hereditary diseases
- can be either unilateral or bilateral
corneal dystrophies
- inherited diseases
- usually bilateral
keratoconus
- progressive thinning and ectasia of cornea
- no evidence of inflammation of vascularization
- causes conical cornea
- associated with down syndrome
fuchs endothelial dystrophy
- loss of endothelial cells -> edema and thickening within cornea
- manifests as stromal edema and bulbous keratophaty
- common indication of corneal transplant
pseudophakatic bullous keratophathy
- endothelial cells decrease following cataract surgery
boarders of anterior chamber
- cornea
- trabecular meshwork
- iris
aqueous humor production
- formed by ciliary body
- enters posterior chamber and bathes lens
- circulates through the pupil to gain access to anterior chamber
- filtered through trabecular meshwork and goes into schelmm’s canal
cataracts
- lens becomes opaque
- due to protein degradation
- can be from age, diabetes, steroids, radiation, trauma
open angle glaucoma
- drainage angle formed by cornea and iris is open
- trabecular meshwork is partially blocked
- mostly due to genetics
closed angle glaucoma
- iris bulges forward to narrow or block drainage angle formed by cornea and iris
- is a medical emergency
- main cause is hyperopia
endophthalmitis
inflammation of vitreous humor
panophthalmitis
inflammation within the eye that involves retina, choroid, and sclera and extends into orbit
opthalmitis
- intraocular inflammation
- vessels in ciliary body and iris become leaky which allows cells and exudate to accumulate in anterior chamber
- can cause adhesions
anterior synechiae
- iris falls forward onto cornea
- causes increased intraocular pressure and optic nerve damage
posterior synechiae
- iris fall backwards onto lens
- causes anterior subcapsular cataract
retinal detachment
separation of neurosensory retina from retinal pigment epithelium
retinal arteriosclerosis
- thickened arteriolar wall -> narrowed vessels
- change of blood color from bright rd to copper and silver
diabetic retinopathy
- thickening of basement membrane of retinal vessels and ciliary body
- can be either non- proliferative or proliferative
non-proliferative diabetic retinopathy
- thick BM
- microaneurysms
- macular edema
- exudates
proliferative diabetic retinopathy
- neuovascularization
- traction retinal detachment
- neovascular glaucoma
what is the main symptom of retinal vessel occlusion?
painless loss of vision
pathogenesis of retinal vessel occlusions
- virchow’s triad of thrombogenesis
- atheroscerotic changes
- damage to retinal vessel wall -> stasis, thrombosis, occlusion
risk factors for retinal vessel occlusions
- age
- HTN
- hyperlipidemia
- DM
- smoking
- increased intraocular pressure
- oral contraceptive pills
central retinal artery occlusion
- sudden cessation of blood supply
- retina swells and acutely becomes optically opaque
- associated with cherry- red spot
retinal vein occlusion
- second most common retinal vascular disease
- veins are thinned walled and leak more easily
- causes flame-shaped hemorrhages
retinitis pigmentosa
- mutation in rods and cones or RPE -> apoptosis of rods and cones
- get varying degrees of visual impairment -> tunnel vision
- fairly common
- retinal atrophy is accompanied by constriction of retinal vessels and optic nerve head atrophy
- retinal pigment epithelium leaks out due to degredation
retinoblastoma
- most common primary intraocular malignancy in kids
- arises when retinal progenitor suffers second hit
- LOF of RB gene
optic nerve pailledema
- tumor or increased CSF pressure -> nerve compression -> edema at head of optic nerve
- typically bilateral
- not associated with visual loss
