Occular diseases 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?
- Difficulty with fine details (e.g. when reading or watching television)
- Fluctuations in vision from hour to hour or day to day
- Blurred, hazy or double vision
- Difficulty seeing at night or in low light
- Being particularly sensitive to glare and light
- Having difficulty focusing
what is glaucoma?
- a disease that affects the optic nerve at the back of the eye
- there is an increased intraocular pressure due to a malfunction in eyes anterior aqueous humor drainage system (as builds pressure that spreads from front to back)
- can lead to optic nerve damage
what is open-angle glaucoma?
- when the iris doesn’t block the trabecular meshwork
- so there is an anterior-chamber angle between them
what is closed-angle glaucoma?
- when the iris blocks the trabecular meshwork
- so there is no anterior-chamber angle between them
what is more common: open or closed angle glaucoma?
open angle glaucoma
what is commonly given for open-angle glaucoma?
latanoprost or dorzolamide
what is commonly given for closed-angle glaucoma?
pilocarpine
what does having a genetic link to glaucoma in the family mean for you as an individual?
it means you are eight times more likely to develop the disease than the general population
what are the risk factors for glaucoma?
- Extreme refractive error
- Diabetes
- Migraine
- Cataracts
- Previous eye injuries
- Sleep apnoea
- Gender, males higher risk
- Corticosteroids
what are the Functional implications of glaucoma?
- Difficulty adjusting to lighting changes (e.g. between indoors and outdoors)
- Occasional blurred vision
- Seeing a halo around lights (angle closure)
- Increased sensitivity to glare and light
- Difficulty identifying the 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 impairment
what do we correct refractive errors with?
by wearing glasses or contact lenses or refractive laser surgery
What are the 4 types of refractive errors?
- HYPEROPIA
- MYOPIA
- ASTIGMATISM
- PRESBYOPIA
what is HYPEROPIA?
long-sightedness (so can’t see close objects)
what happens in HYPEROPIA?
object focuses behind the retina
what do we treat HYPEROPIA with?
biconvex lenses
what is MYOPIA?
shortsightedness
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 a rigid eye lens (PRESBYOPIA)?
can’t focus the light
what are the Functional implications of refractive error?
- hyperopia - difficulty seeing near objects
- myopia - difficulty seeing things in the distance
- astigmatism - blurred vision
- presbyopia - difficulty seeing near objects occurs from 40yrs old and onwards
what is HORDEOLUM (STYE)?
inflammatory infection of the hair follicle of the eye lid
what is CHALAZION (MEIBOMIAN CYST)?
collection of fluid or soft mass cyst
what is BLEPHARITIS?
inflammation of the margins of the eye lids
What is ENTROPION?
inversion of eye lid into eye
What is ECTROPON?
outurned eye lids
What is CONJUNCTIVITIS?
inflammation of the conjunctiva causing pink eye
what causes conjunctivitis?
- Viral / bacterial infection
- irritants e.g. allergies, UV light or chemicals
what are the symptoms of conjunctivitis?
– Redness / swelling / itching
– tearing when exposed to light
– pus if infectious
what is given for bacterial conjunctivitis?
– Redness / swelling / itching
– tearing when exposed to light
– pus if infectious
– “contagious” with contaminated hands, washcloths
what is given for viral conjunctivitis?
- Lubricants
- Steroids if keratitis
what is given for allergic conjunctivitis?
- mast cell stabiliser
- antihistamine
- steroid
what is given for ocular inflammation?
- Corticosteroids
- Steroid-Antibiotic Combinations
- Non-Steroidal Anti-inflammatory Drugs (NSAIDS)
- Oral Analgesics
what is given for ocular infections?
- Topical Antibiotics
- Oral Antibiotics
- Anti-Viral
- Analgesics
what are mydriatics?
drugs that cause pupil dilation
what do we give mydriatics for?
- to examine the fundus
2. for pain relief in Iritis
what is the most commonly used mydriatic called?
Mydriacyl (Tropicamide)
what is the effect of cycloplegics?
they cause cycloplegia which is paralysis of the ciliary muscles to cause pupil dilation
what is the side effect of cycloplegics and mydriatics?
blurred vision
what are miotics?
drugs that constrict the pupil e.g. pilocarpine
what are miotics used to treat?
glaucoma
what are the side effects of miotics?
- night blindness
- stinging on instillation
- brow ache or spasm
