Glaucoma & its Management Flashcards
What is glaucoma?
It is raised ocular pressure in the eye due to increased aqueous humour, causing optic nerve damage & loss of visual field
What is the threshold pressure level for someone to be diagnosed with glaucoma?
> 12mm/Hg
What is the function of aqueous humour in the eye?
It provides nutrients to the cornea/lens of the eye, and maintain pressure
What happens when production/drainage of aqueous humour in the eye is compromised?
Pressure in the eye increases & can destroy delicate parts of the eye.
What is the main mechanism of action for drugs used in glaucoma?
They either increase aqueous humour drainage, or stop its production.
What must occur to allow the drainage of aqueous humour?
The angle between the iris & the cornea must always be open to allow drainage.
What are the 3 types of glaucoma?
- Congenital & development glaucoma
- Primary adult glaucoma - either primary open angle glaucoma (POAG), or primary angle closure glaucoma (PACG)
- Secondary glaucoma
Which type of primary glaucoma is likely to cause blindness?
POAG - primary open angle glaucoma.
What are the risk factors for glaucoma?
- > 40 years old
- Family history
- Diabetes
- Myopia - short/near sighted
What are the symptoms of POAG?
- Asymptomatic in most cases
- Vision field loss
- No pain/discomfort
- Acute POAG: redness, blurred vision, pain, nausea/vomiting, cloudiness of eye
What are the clinical signs for identifying POAG?
- IOP raised >12mm/Hg
- Delicate parts of the eye lost (>50%)
- Visual field impairment - starting with peripheral, then central vision
Why is acetazolamide not given for glaucoma, even though it can reduce IOP?
- It needs a high dose to be effective
- Can lead to systemic effects
- Its administration can be difficult
- Poor adherence can arise from it
How can we prevent the need for multiple eye drops to be instilled?
The medicine can be in contact lenses, which can act as a reservoir for the drug and prevent multiple eye drops being needed.
What are punctal plugs?
They are devices inserted in the eyelid which delays the drainage of the drug and acts as a sustained release reservoir for the drug
Why are preservatives used in eye drops?
- They maintain stability of the drug
2. They prevent bacterial growth from the water in the eye drops
What side effect can preservatives in eye drops cause?
They can be irritants, and compromise the integrity of tears & the corneal surface
What are the 5 glaucoma drugs that can be used?
- B-blockers - reduces production of aq. humour & lowers IOP
- Prostaglandin analogues - 1st line treatment, used OD to control IOP for 24h
- Sympathomimetic drugs - A adrenergic agonists
- Carbonic anhydrase inhibitors
- Miotics
What are some examples of B-blockers used in glaucoma?
- Betaxolol
- Timolol
- Carteolol
- Levonbunolol
Why aren’t B-blockers favoured in glaucoma?
Because they induce many side effects, especially in the CV system.
Must avoid using in patients with bradycardia, uncontrolled asthma/HF, COPD
Why are gel B-blockers preferred than eye drops?
Because gels are more viscous, which can stick to the ocular surface longer & reduce the drugs use from BD to OD
- E.G. Timolol combinations
What are some examples of prostaglandin analogues in glaucoma?
- Latanoprost
- Tafluprost
- Travoprost
- Bimatoprost
Why aren’t gel prostaglandin analogues for glaucoma needed?
Because PG analogues are used OD which cover 24h, so no gel is needed.
What are some side effects of PG analogues in glaucoma?
- Changes in eye colour
- Increased hair growth around eyes
- Dry eyes
- Rash
- Photophobia
What can PG analogues also be used for, besides glaucoma treatment?
They can also be used cosmetically to darken, thicken and lengthen eyelashes.
What 2 carbonic anhydrase inhibitor eye drops are used in the UK?
- Brinzolamide
2. Dorzolamide
What specific side effect can carbonic anhydrase inhibitors cause?
They can reduce blood sugar levels, since they are based on sulphonamides.
What are some examples of sympathomimetics?
- Brimonidine
2. Apraclonidine
What 2 side effects can sympathomimetics cause?
- CVD
2. Cerebral/coronary insufficiency
What are some common therapeutic problems in glaucoma?
- Lack of adherence
- Contraindications
- Intolerance to the drug
- Hypersensitivity
