Pathophysiology of eye and care Flashcards
80% of vision loss is causes by 5 conditions
- Age related macular degeneration (AMD)
- Cataract
- Diabetic retinopathy
- Glaucoma
- Under-corrected and uncorrected refractive error
What percentage of vision loss is preventable and treatable?
75%
People with vision impairment are at a greater risk of suffering from secondary conditions (6)
- Falls
- Depression
- Early special accommodation
- Increased risk of hip fracture
- Increased early mortality
- Social isolation
Vitreous body is filled with vitreous fluid (humor) purpose
Allows the eye to keep its shape
Conjunctiva
A thin mucus membrane that covers the eye
Bulbar conjunctiva with sclera beneath
The white of the eye
Limbus
The junction of cornea and sclera
How does the lens work?
Lens projects inverted image on to retina which produces a signal and sends to the brain to invert it back.
2 types of photosensitive cells
Rods (120 million) and cones (6 million)
Rods are sensitive to…
light
Cones are sensitive to…
colours
Purpose of retinal blood vessels
Nutrition and blood supply to the retina.
Where in the fovea?
The centre of the macula
What is in the fovea?
Cones (colours)
What is in the periphery of the retina?
There are more rods and it becomes slightly thinner
Retinal detachment from bleeding in the eye can cause…
blindness
What is retina detachment?
The retina is lifted or pulled from normal position. Usually occurs when small areas of the retina become torn.
What is the macula?
The area next to optic disc that defines fine details at the centre of visual field
What is age-related macular degeneration (AMD)?
A chronic degenerative condition that affects the central vision; not enough blood supply to area.
What part of the eye is affected in age-related macular degeneration (AMD)?
The macular, disappearance of central vision due to deterioration of pigment layer of retina
What causes degeneration of the macular?
Abnormal blood vessels leaking fluid or blood into the macular.
How does age-related macular degeneration affect the vision?
Black/dankness at the centre of vision.
Functional implications of AMD (7)
- 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?
A cataract is the clouding of the lens inside the eye. With a cataract, light is scattered as it enters the eye, causing blurred vision; gradual deterioration of lens.
What does early cataract do in spectacle prescription?
Myopic shift so see an optometrist to change glasses prescription
What are the 3 types of cataract?
Congenital, senile and secondary
What part of the eye does cataract affect?
The lens
What can increase the risk of cataract? (3)
- Long term use of corticosteroids can increase risk of cataracts
- Exposure to UV light can also increase the risk
- Ageing, smoking and having diabetes can increase the risk of developing cataract.
How does cataract affect the vision?
Foggy images and the changes in colour perception, yellowing.
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?
It affects the small blood vessels of the retina. Blood vessels begin to leak and bleed inside the eye
What percentage of people with type 2 diabetes will develop retinopathy?
22%
What to things to do with diabetes, can increase the risk of diabetic retinopathy?
Diabetic kidney disease and type 1 diabetes
How does diabetic retinopathy affect the vision?
The appearance of “clouds” moving in the vision which obstruct a person’s sight.
What part of the eye is affected with diabetic retinopathy?
Leaking blood vessels in the retina
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 are the 4 stages of diabetic retinopathy?
Mild non proliferative
Moderate non proliferative
Sever non proliferative
Proliferative
What treatment is needed during the first 3 stages of diabetic retinopathy?
No treatment unless muscular oedema.
What is proliferative in diabetic retinopathy treated?
Surgery, scatter laser treatment to shrink abnormal blood vessels.
What are some of the complications with scatter laser treatment?
Some loss of vison, but saves the rest of sight
Might slightly reduce colour and night vision
How is macular oedema treated?
Focal laser treatment. Stabilises vision and can reduce risk of vision loss by 50%.
What is glaucoma?
It is a disease that affects the optic nerve at the back of the eye.
Increased intraocular pressure due to a malfunction in eyes aqueous humor drainage system - can lead to optic nerve damage.
What reduces progression of glaucoma?
Relieving pressure on the nerve reduces progression of the disease.
What happens with glaucoma over time?
Gradual loss of peripheral vision.
If untreated - eventually complete vision loss.
What can early detection of glaucoma do?
Early detection and treatment can slow the vision loss.
What part of the eye is affected by glaucoma?
Optic nerve at the back of the eye
How does glaucoma affect the vision?
Peripherally vison so dark around the edges
Where does the fluid flow in glaucoma?
Behind the iris, through the pupil, into the aqueous part, then out though trabecular meshwork.
What is closed angled glaucoma?
The iris blocking the trabecular meshwork
What is opened angled glaucoma?
The iris NOT blocking the trabecular meshwork
What type of glaucoma is more common?
Opened angled glaucoma
What is the treatment aim for glaucoma?
Inhibition or decrease in the aqueous formation. And an increase of uveoscleral outflow.
Risk factors for glaucoma
- Extreme refractive error
- Diabetes
- Migraine
- Cataracts
- Previous eye injuries
- Sleep apnoea
- Gender, males higher risk
- Corticosteroids can increase the risk of developing glaucoma
Functional implications of glaucoma
- No functional implications in early stages, silent disease
- 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?
Refractive error is a focusing disorder of the eye.
How can refractive error be corrected?
It is correctable by wearing glasses or contact lenses or refractive laser surgery (selected cases)
4 types of refractive error?
- HYPEROPIA
- MYOPIA
- ASTIGMATISM
- PRESBYOPIA
How does refractive error affect the vision?
Blurred vision
What is hyperopi?
Far, long sightedness
Hyperopia mechanism
- object focuses behind the retina
- able to see only far objects
What is myopia?
Near, short sightedness
Myopia mechanism
- object focuses in front of the retina
- able to see only close objects
What is astigmatism?
Change in the shape of the lens
Astigmatism mechanism
- abnormal shaped cornea (egg shape instead of spherical)
- object is partially clear and other blurred
What is presbyopia?
The lens not functioning properly
Presbyopia mechanism
- Rigidity of the lens (old age)
- unable to focus
Functional implications of refractive error: long-sightedness (hyperopia)
difficulty seeing near objects
Functional implications of refractive error: short-sightedness (myopia)
difficulty seeing things in the distance
Functional implications of refractive error: astigmatism
blurred vision
Functional implications of refractive error: presbyopia (age focus difficulty)
difficulty seeing near objects occurs from 40 and onwards
Hordeolum (stye)
Inflammatory infection of the hair follicle of the eye lid
Chalazion (meibomian cyst)
Collection of fluid or soft mass cyst
Blepharitis
Inflammation of the margins of the eye lids
Entropion
Inversion of eye lid into eye
Ectropion
Outurned eye lids
Conjunctivitis
Pink eye
Conjunctivitis mechanism
Inflammation of the conjunctiva
Conjunctivitis etiology
- Viral / bacterial
2. Irritants (allergies, chemicals, UV light)
Conjunctivitis symptoms and signs
- Redness / swelling / itching
- tearing when exposed to light
- pus if infectious
- “contagious” with contaminated hands, washcloths
4 types of conjunctivitis
Bacterial, viral, chlamydial, allergic
Treatment for bacterial conjunctivitis
Chloramphenicol
Lid hygiene
Treatment for viral conjunctivitis
Lubricants
Steroids if keratitis
Treatment for chlamydial conjunctivitis
GUM clinic
Azithromycin
Erythromycin
Treatment for allergic conjunctivitis
Lid hygiene,
mast cell stabiliser,
antihistamine,
steroid
Ocular inflammation treatment (4)
- Corticosteroids
- Steroid-Antibiotic Combinations
- Non-Steroidal Anti-inflammatory Drugs (NSAIDS)
- Oral Analgesics
Ocular infection treatment (4)
- Topical Antibiotics
- Oral Antibiotics
- Anti-Viral
- Analgesics
What are mydriatics?
Cause pupil dilation
What are mydriatics used for?
Examine fundus (can see more of retina)
Used as pain relief
Example of mydriatic
Mydriacyl (Tropicamide)
Mydriatics onset
15 mins can last for 3-6 hours
What affect does mydriatics have on vision?
Blurs
What are cycloplegics?
Cause mydriasis and cycloplegia
What is mydriasis?
Dilation of the pupil
What is cycloplegia?
Paralysis of the ciliary muscle that controls focusing of the light rays entering the eye by changing the shape of the crystalline lens.
What are miotics?
Causes pupil constriction
What are miotics used for?
Treatment of glaucoma
Side effects of miotics
- Night blindness
- Stinging on instillation
- Brown ache or spasm
What is miosis?
Constriction of the pupil
What can happen with long term use of pilocarpine (miotic) cause?
Difficulty to dilate pupil
Example of miotic
Pilocarpine
What to do:
Babies
REFER
Can’t really diagnose
Not much OTC
Cannot use Chloramphenicol for under 2 years
What to do:
Babies with sticky eyes from birth
REFER
Could be indication of blockage in tear duct
Infection going though birth canal
What to do:
Patients who have undergone ophthalmic surgery or eye laser treatment
REFER
Not sure about surgery implications
What to do:
For chloramphenicol –personal or family history of bone marrow problems
REFER
Contraindication for it to be used in these patients
What to do:
Associated pain or swelling around the eye or face
REFER
What to do:
Photophobia (Sensitivity to light)
REFER
Cannot really give any treatment
What to do:
Unusual appearance, e.g. cloudiness
REFER
New presentation would require examination
What to do:
Restricted eye movement
REFER
What to do:
Pain inside the eye
REFER
What to do:
Visual disturbance
REFER
What to do:
Foreign bodies in the eye
REFER
Needs to be removed appropriately
What to do:
Reported trauma to the eye
REFER
Needs to get checked out
What to do:
Presence of systemic symptoms, e.g. headache
REFER
What to do:
Unusual appearance of the eye, e.g. irregular shaped pupil –a feature of acute angle closure glaucoma
REFER
What to do:
Recurring problems
REFER
What to do:
Any occurring after trauma to the eye
REFER
What to do:
If already seen the doctor
REFER
What to do:
If tried another remedy
REFER
What to do:
On any other medicines
REFER
What is the basis of referral?
Required further examination and specialist treatment
What to do:
Drug induced eye conditions
REFER
Eye complaints in community pharmacy?
- Red eye
- Disorders of eyelid
- Bacterial conjunctivitis
- Tear disorders
Red eye presentation may be more serious when…
With pain and or visual loss
Possible cause of red eye
Conjunctivitis (allergic or infective)
Subconjunctival haemorrhage
‘inflamed’ eyes
Difference between allergic and infective
Infective starts in one then goes to other. Allergic both at the same time.
When does allergic conjunctivitis usually resolve?
7-10 days once exposure has stopped
What does it mean when conjunctivitis is self-limiting?
It will go by itself with body defence mechanisms.
Which conjunctivitis takes considerably longer to heal?
Adenoviral
When does bacterial conjunctivitis usually resolve?
7-10 days even without treatment
What type of OTC treatment can be used for conjunctivitis?
Antibiotic or help loosed hardened discharge on lids
Antiseptics for conjunctivitis
Propamidine isetionate drops
Dibromopropamidine isetionate eye ointment
Antibacterial for conjunctivitis
Chloramphenicol drops and ointment
How is chloramphenicol drops used?
Every 2 hours for first 2 days
Every 4 hours there after
How is chloramphenicol ointment used?
3-4 times a day but generally Used on bottom waterline at night.
What do antiseptics do?
More for cleaning the eye and prevent further infection.
Chloramphenicol and contact lens user?
Stop wearing contacts (preservatives can form deposits on lens and lens can get contaminated) or refer.
What may contact lenses users use instead of chloramphenicol?
Signal use vial as it has not got preservatives.
What is the usual course for chloramphenicol?
5 days. Should discard after this.
What to do if chloramphenicol shows no improvement after 2 days?
If not improvement after 48 hours then referred (resistance or viral)
Can you share bottles of chloramphenicol?
No, usually get bottle for each eye
How you use eye drops?
Pull lower lid and drop into pocket, without touching eyes and eyelashes.
Side effects of eye drops like chloramphenicol?
Transient stinging, burning and blurring of vision.
How is chloramphenicol drops stored?
In the fridge
If your not sure if its conjunctivitis what should you do?
Not give chloramphenicol due to antibiotic resistance. REFER
What to do with chlamydial conjunctivitis?
More serious so required REFFERAL.
What treatment is used in chlamydial conjunctivitis?
Oral macrolide or tetracycline (antibiotic given by doc)
Allergic conjunctivitis advice
Avoid/minimise exposure to trigger
Cold compress for eyes
Allergic conjunctivitis treatment
Oral antihistamines
Antihistaminic eye drop with a vasoconstrictor Sodium cromoglicate
When do you use Sodium cromoglicate in allergic conjunctivitis?
More suitable for long-term: fast and effective and safe for prolonged periods?
When do you use Antihistaminic eye drop with a vasoconstrictor in allergic conjunctivitis?
Short-term or intermittent use
Why should steroid use be avoided for allergic conjunctivitis?
Can cause cataract, glaucoma or severe infection. (Only available on prescription)
What is Subconjunctival haemorrhage?
Small vessel burst
How is Subconjunctival haemorrhage treated?
Resolves spontaneously in 7-14 days
When do you refer Subconjunctival haemorrhage?
If recurring or on warfarin
What can cause inflamed eyes?
- Tired/irritated
- Over-exposure to smoky/dusty air, or regular rubbing
- Overworking: reduction in blink frequency and poor corneal wetting
What can be used for inflamed eyes?
Eye lotions or drops containing astringents, such as witch hazel or lubricants as short-term measure: soothing
What to do it dry eye persist?
REFER Maybe dry eye condition
Why would you refer is Subconjunctival haemorrhage is recurring?
It may be undiagnosed hypertension.
Why would you refer is Subconjunctival haemorrhage if on warfarin?
Indication of bleeding time, anticoagulation not working so well.
What is a stye?
Acute localised abscess usually caused by Staphylococcal infection
How to treat stye?
Resolves spontaneously
How to speed up stye healing?
With hot compress to closed lid for several mins each day.
How does applying a warm compress speed healing of the stye?
It brings up and puss building up in the absence to the surface more quickly allowing is seep out and/or heal.
When to refer stye to GP?
If not resolved after 7 days
What may happen if not resolved?
Surgical treatment, often removing an eyelash
What is a Chalazion?
Cyst of meibomian gland that secretes fluid to stop eyes sticking together
How do you treat a chalazion?
Resolves spontaneously but may take few weeks
Treat same as styes
What would happen if the chalazion (cyst) doesn’t heal?
Cysts that don’t resolve may require surgery to drain swelling
What is Marginal blepharitis?
Chronic condition inflammation of the margin of the eyelid
Can Marginal blepharitis be cured?
Symptoms can be improved but may not be cured permanently
What is important for Marginal blepharitis treatment?
Compliance to treatment is important and lid hygiene
Is sight affected with Marginal blepharitis?
Sight rarely affected as it is on the outside of the eye.
Can you wear contacts with Marginal blepharitis?
Contact lenses should not be worn during any eye infection as it will cause increased inflammation and sensitivity.
Eyelid hygiene: warm compress
Warm compress to lids and eye margins to loosen crusts and cleans more effectively and comfortably
Eyelid hygiene: Massage eyelids
Gently roll first finger on lids to help push out any oily fluid from eyelid gland
Eyelid hygiene: Cleaning of eyelids
Mix of 2 parts baby shampoo with 10 parts warm water. Applied with a clean cloth or cotton bud and rubbed along the margins
Or lid wipes
Eyelid hygiene: How often should you cleanse eyes?
Twice daily for several weeks.
Once improved reduce to 1 times daily.
Eyelid hygiene: Eye makeup
Especially eye liner can contribute to infection. Should discard in eye infection as it will be contaminated.
Eyelid hygiene: When to refer to GP?
Symptoms not resolved in 7 days
How is Bacterial blepharitis treated?
With antibacterial ointment rubbed into eyelashes and at base of lashes 2-3 times a day for 7 days.
Is OTC chloramphenicol licenced for bacterial blepharitis?
No- only licensed for conjunctivitis
What medication can be used for bacterial blepharitis?
Fusidic acid viscous drops. But POM.
When is Systemic treatment (e.g. oral tablets) occasionally required for bacterial blepharitis?
Usually undertaken after culturing organisms (swab) from the eye lid margins and determining antibiotic sensitivity
How long are oral antibiotics for bacterial blepharitis given for?
Oral antibiotics such as tetracyclines given for 3 months or longer may be required
Why do oral antibiotics need to be given for 3 months or longer?
For something taken orally to have an effect on a superficial part of the body is going to take longer to take action.
Watering eyes
Excessive lacrimation
Watering eyes with no other symptoms
May be associated with interrupted drainage of tear film often as a result of blockage of nasolacrimal duct
What do 20% of infants develop during the first month of life?
Congenital lacrimation obstruction, but usually resolves spontaneously.
What may GPs do if a infant has Congenital lacrimation obstruction?
Apply pressure with a finger to the lacrimal sac at the internal corner of the eye and lightly massage the duct beneath.
What can happen if the fluid is not released in the Congenital lacrimation obstruction?
Pressure may increase.
What would happen to and adult with Congenital lacrimation obstruction?
Messaging usually ineffective. Requires specialist and may need surgery.
How may watering eyes be due to dry eyes?
Part of the inflammatory process.
What can a reason for watering eyes particularly found in older people?
Ectropion or Entropin conditions.
What to do: Ectropion or Entropin conditions.
REFER
Minor surgical procedure can correct the problem.
What is Ectropion or Entropin?
Where the eyelid turns in or out
Dry eyes
The loss of the ability to produce tears. This is usually lifelong.
Who are more prone to dry eyes?
Contact lens wearers.
When may dry eyes be acute and temporary?
Dry eyes with an infection
What to do: dry eyes
REFER
To eliminate associated problems such as corneal ulceration.
Treatment for dry eyes
Lubrication, to allow inflammation of eye surface to subside and then maintain lubrication so patient is symptom free.
Tear substitutes are recommended as they have prolonged retention time.
What is the issue with less thick dry eye drops?
Need to be applied more often.
What is the issue with more thick dry eye drops?
Greasy
Stickiness
sometimes crystallisation on the lid
Blurring vision
What is recommended for a patient that needs to use dry eye drops for more than 6 times a day?
Preservative free, to reduce damage by benzalkonium chloride which disrupts tear film.
What drops can be used for glaucoma? (3)
Parasympathomimetic drops
Sympathomimetic drops
Beta-blocker drops
How to use eye drops for glaucoma
Use of punctual occlusion or simply shutting eyes for several mins after application can reduce drug entry into lachrymal ducts and subsequently systemic circulation
Prostaglandin analogues and prostamides advantage
Have advantage of once daily application. Warn patients that may increase brown pigmentation in iris
Carbonic anhydrase inhibitors
2 available: dorzolamide and brinzolamide. The latter is more comfortable because of neutral pH
Screening for glaucoma
> 40 years encouraged for check-up and 1st degree relatives can get free eye tests.
Side effects caused by ocular products
Typical local side effects: transient stinging,
burning, itching or irritation
Difficulties with eye drop adherence
Difficulty aiming bottle
Shaky hands
Reflex blinking
Where can eye drop be put?
In temporal corner of lower conjunctival sac.
How can you stop getting the taste of the drops?
Press a finger against the inner corner of the eye by the nose for approx. min. after using drops may help to stop drops draining into nose and throat.
Advice for using eye drops (4)
- Tilt head back
- Lower lid pulled down
- Patient looking towards nose
- Wash hands before and after
What does looking at your nose do when using eye drops?
Won’t see drop descending.
Rigid gas permeable contacts
Smaller than soft lenses and rest within corneal area
What is rigid gas permeable contacts good for?
Thought to be better at correcting irregularly shaped eyes (takes longer to get used to).
How often are rigid permeable contacts replaced?
More durable so replaced every 6-12months
Soft contact lenses
Like thick cling-film
Larger and cover cornea so lens can be seen on sclera
How often do you replace soft contact lenses?
Replacement may be daily, 2-weekly, monthly or 3monthly
May be daily-wear or 30 days continuous wear
How do you prevent drying of soft contact lenses?
Incorporate water to prevent drying out
Problems that can occur with contact lenses?
- Inappropriate fit, prescription or extended wear
- aged contact lenses
- Inherent patient problem with tear film, lids or lashes
- Immunological factors
- Microbial keratitis
What is Microbial keratitis?
Type of bacterial infections
- Pseudomonas aeruginosa
- Acanthamoeba
Soft and hard contact lens care: Daily cleaning
Daily use of surfactant to remove mucins, lipids, eye cosmetics and dirt
Soft and hard contact lens care: Disinfection
Daily with either hot/cold disinfectant
Soft and hard contact lens care: Protein removal
Usually once a week to remove tear proteins
Soft contact lens care: Saline solutions
Used for rinsing or as medium for protein-removing tablets
Soft and hard contact lens care: Multipurpose solutions
Combine functions of cleansing, rinsing and disinfection
Soft and hard contact lens care: Lubricant or comfort drops
May require especially when they are getting used to this.
Hard contact lens care: Wetting solutions
Need to ensure lenses come into complete contact with tear film. Improve comfort on insertion, provide buffer between lens and finger during insertion and prevent contamination and facilitate even spread of tears over lens surface. Usually same solution used for soaking and wetting
Rigid gas permeable lenses care
Deposits may be more difficult to remove than hard lenses.
Same care as hard lenses
Reduction in tear flow (Contact lens issues)
Can cause lens discomfort can follow drugs with antimuscarinic side effects
What can be signs of deposits on lenses?
Discolouration, visions issues or irritation
Which lenses can be used with OTC eye preps?
Hard and rigid gas permeable.
Why are soft lenses less recommended to use with OTC eye preps?
Potential to absorb comportment particularly the preservative benzalkonium chloride.
Which drops can be used with soft lenses?
With chlorhexidine
How may they use contacts when using eye preps?
Wait 15 mins after treatment.
Lens intolerance (Contact lens issues)
Can be caused by hormone preparations
Lens discolouration (Contact lens issues)
Can occur after oral administration of beta blockers, nitrofurantoin, rifampicin, sulfasalazine and tetracyclines
Hormonal changes and contact lenses
Problems such as dry eyes and blurred vision can result from hormonal changes: thought to be deficiencies in lipid component of tear film, resulting in increased tear evaporation and reduction in aqueous and mucin layers.
What can be used for someone with poor manual dexterity for eye drops?
OptiCare universal: handheld reusable plastic dispenser
What is good about the eye drop dispenser?
It allows for accurate positioning of the eye and only requires 25% of force of squeezing.
Cold sores and contact lenses
Not to wear during infection to avoid spread. This is because it affect mucosal membranes.
