occular disease pathophysiology Flashcards
what five conditions cause 80% of vision loss?
- Age-related Macular Degeneration (AMD)
- Cataract
- Diabetic retinopathy
- Glaucoma
- Under-corrected and uncorrected refractive error
People with vision impairment are at a greater risk of suffering from secondary conditions such as what?
– falls
– depression
– early special accommodation – increased risk of hip fracture – increased early mortality
– social isolation
where are tears stored before you cry?
in the lacrimal gland
what do tears travel via to move from the lacrimal glands to the eye
lacrimal gland duct
what do tears through when you to cause you to produce mucus when you cry?
lacrimal duct
what part of the eye determines your eye colour?
iris
what are the muscles that contract and relax to change the size of the pupil?
ciliary muscles
what attaches the ciliary muscles to the lens?
suspensory ligaments
what fills up the void in the eye between the lens and the retina?
vitreous humour (liquid)
what is the role of the vitreous humour?
to keep the eye ball shape
what is the white covering around the eye called?
the sclera
what is embedded between the sclera and the retina?
the choroid
what is the function of the choroid?
It is full of blood vessels to supply the eye with nutrients
what is the blind spot in the eye called?
the optic disc
where is the fovea located?
in the centre of the macula lutea on the retina
what does the fovea do?
it is responsible for sharp central vision (where we need to pay close detail to things)
what is located on the retina to create an image of what we see?
rod and cones
what are rods sensitive to?
light
what are cones sensitive to?
colours
where on the retina do we find more cones?
nearer the macula
which do we have more of, rods or cones?
rods (120million)
cones = 6million
What is age-related macular degeneration (AMD)?
A chronic degenerative condition that affects the central vision (the macula-fovea part) due to poor blood supply to the area. (disappearance of central vision due to deterioration of pigment layer of retina)
What are functional implications of AMD?
- Difficulty distinguishing people’s faces
- Difficulty with close work
- Perceiving straight lines as distorted or curved
- Unable to differentiate between the footpath and road
- Difficulty identifying the edge of steps if there is no colour contrast
- Unable to determine traffic light changes
- Difficulty reading, with blurred words and letters running together
What is a cataract?
- the clouding of the lens inside the eye.
- light is scattered as it enters the eye, causing blurred vision
- gradual deterioration of lens.
what can increase the risk of developing cataract?
- Long term use of corticosteroids
- Exposure to UV light
- Ageing, smoking and having diabetes
what type of cataract does prolonged corticosteroid therapy cause?
posterior subcapsular cataract
what is an image like for AMD patients?
parts of the image will be black (they won’t be able to see everything)
what is an image like for cataract patients?
foggy and yellowish
what are Functional implications of cataract?
- Blurred vision
- Reduced contrast
- Having difficulty judging depth
- Seeing a halo or double vision around lights at night
- Seeing images as if through a veil/smoke
- Being particularly sensitive to glare and light
- Having dulled colour vision.
What is diabetic retinopathy?
- a complication of diabetes affecting small blood vessels of the retina.
- the blood vessels leak and bleed in the eye
what type of people have a greater risk of developing diabetic retinopathy?
Those who have
- had diabetes for many years
- diabetic kidney disease
- type 1 diabetes
what is the image like for those with diabetic retinopathy?
-‘clouds’ in the persons vision causing an obstruction to a person’s sight
what are the Functional implications of diabetic retinopathy?
- difficult with fine details
- fluctuations in vision from hr to hr or day to day
- blurred hazy or double vision
- difficulty seeing in night or low light
- sensitivie to glare and light
- difficult focusing
what is glaucoma
disease affecting optic nerve at the back of the eye
increased intraocular pressure to malfunction in eyes anterior aqueous humor drainage system
leads to optic nerve damage
open-angle glaucoma
when iris doesn’t block the trabecular meshwork
so there is anterior-chamber angle between them
what is closed- angle glaucoma
when iris blocks trabecular meshwork
no anterior -chamber angle between them
whats more common open or closed angle glaucoma
open angle glaucoma
what is commonly given for open-angle glaucoma
latanoprost or dorzolamide
what is given for clsoed- angle glaucoma
pilocarpine
what does having a genetic link to glaucoma in the family mean for you as an individual?
means you are eight times more likely to develop the disease than the general popuation
what are the risk factors for glaucoma?
extreme refractive error diabetes migraine cataracts prevoius eye injury sleep apnora gender, males higher risk corticosteroids
what are the Functional implications of glaucoma?
diffciulty adjusting to lighting changes
occasional blurred vision
seeing halo around lights
increased sensitivty to glare and light
difficult identifying edge of steps or road
tripping over or bumping into objects
What is refractive error?
a focusing disorder of the eye
most common cause of vision impairement
what do we correct refractive errors with
by wearing glasses or contact lessions or refractive laser surgery
4 types of refractive errors
hyperopia
myopia
astigmatism
presbyopia
what is hyperopia
long isghtedness
what happens in hyperopia
object focuses behind the retina
what do we treat hyperopia with
biconvex lenses
what is myopia
shortsghtedness
what happens in myopia
object focuses in front of the retina
what do we treat myopia with
biconcave lens
what is astigmatism
abnormal shaped cornea- egg shape instead of spherical
what is the image of the object like with astigmatism
partially clear and other blurred due to object laying on the retina at an angle- focus images at different distances
how do we treat astigmatism
using a rigid curved lens
what is presbyopia
rigidity of the eye lens
what commonly causes presbyopia
old age
what is the issue with having rigid eye lens
can’t focus the light
what are the functional implications of refractive eroor
hyperopia - difficulty seeing near objects
myopia- difficulty seeing things in the distance
astigmatism- blurred vision
presbyopia- difficulty seeing near objects occurs from 40 yrs old and onwards
what is hordeolum
inflammatory infection of the hair follice of the eye lid
what is chalazion
collection of fluid or soft mass cyst
what is blepharitis
inflamamtion of the margins of the eye lid
what is entropion
inversion of eye lid into eye
what is ectropon
outurned eye lids
what is conjuctivitis
inflammation of the conjuctiva causing pink eye
what causes conjuctivitis
viral bacterial infection
irritants
symtptoms of conjuctivities
redness
tearing
pus
what is given for viral conjuctivitis
lubricants
steroids if keratitis
what is given for allergic conjuctivitis
mast cell stabiliser
antihistamine steroid
what is given for ocular inflammation
corticosteroids
steroid antibiotic combinations
NSAID
oral analgesic
what is given for ocular infections
topical antibitics
oral antibiotics
anti-viral
analgesic
what are mydriatics
drugs cauisng pupil dilation
what do we give mydiatrics for
examine fundus
pain relif in iritis
most commonly used mydriatic is
mydriacyl
effects of cycloplegics
they cause cycloplegia which is paralysis of the ciliary muscles to case pupil dilation
side effect of cycloplegics and mydriatics
blurred vision
what are miotics
drugs which constrict the pupil e.g. pilocarpine
what are miotics used to treat
glaucoma
what are side effecrs of miotics
night blindenss
stinging n instilation
brow ache or spasm
