1: Glaucoma Flashcards
Define glaucoma
Group of eye diseases that result in damage to optic nerve with or without raised IOP
What are the two types of glaucoma
Open-angle
Close-angle
What is open glaucoma
Iris does not obstruct the trabecular meshwork - enabling drainage of aqueous humour. This presents as a gradual loss of peripheral vision until late stages
What is close angle glaucoma
Iris obstructs the trabecular meshwork - preventing drainage of aqueous humour
What type of glaucoma is an emergency
Close-angle glaucoma
What are the 3 chambers of the eye
Anterior Aqueous Chamber
Posterior Aqueous Chamber
Posterior vitreous chamber
What is the anterior aqueous chamber
From lens to cornea
What is the posterior aqueous chamber
From lens to iris
What is the vitreous chamber
lens to retina
Explain circulation of aqueous humour and pathology in glaucoma
- Aqueous humour is produced by ciliary epithelium and released into posterior chamber.
- It passes from posterior chamber to anterior chamber
- It is drained from anterior chamber by canal of schlemm to episcleral venous
- If this is occluded, pressure may increase to cause intraocular HTN
- High pressure can damage optic.N
What defines intraocular HTN in mmHg
> 21
What defines intra-ocular HTN in kPa
> 2.8kPa
What patients is open-angle glaucoma more common in
> 40
Female
Eastern-Asian
What are the two types of open-angle glaucoma
Primary
Secondary
What is primary angle close glaucoma
Idiopathic
What is a risk factor for primary angle-closure glaucoma and why
Hypermetropia (Long-sightedness) as this means a shorter eyeball increasing risk of the iris occluding the trabecular meshwork
What is secondary angle-closure glaucoma
Due to trauma
Why does traumatic haemorrhage cause angle-closure glaucoma
Traumatic haemorrhage pushes the posterior chamber forward increasing risk if will occlude the trabecular meshwork
What are 3 risk factors for angle-closure glaucoma
- Hypermetropia
- Cataracts
- Cyclopentolate
What medication may precipitate angle-closure glaucoma
Cyclopentolate used for uveitis
How does acute angle-closure glaucoma present clinically
Acute-onset:
- Blurring vision, Halos at night
- Severe eye pain followed by headache
- Red-eye
- Eye watering
- N+V
How will the pupil present in angle-closure glaucoma
Fixed mid-dilated pupil
What should be avoided in acute angle-closure glaucoma and why
Dark rooms and eye-patches as they cause pupil dilation further narrowing the network
What should happen with acute angle-closure glaucoma
Immediate referral to opthalmology
What is used to look at the eye in acute angle-closure glaucoma
Goinoscopy
What does a goinoscopy look at
Goinoscopy - able to look at the iridocorneal angle
Why do patients need an urgent referral to ophthalmology
For intra-ocular pressure monitoring and medication
What 3 medications should be started in acute angle-closure glaucoma
B-blockers
Acetazolamide
Pilocarpine
How can the medications for acute angle-closure glaucoma be remembered
BAP
What B-blocker is given in acute glaucoma and how
topical Timolol
What is the role of timolol
stops aqueous humour production
how is pilocarpine given
topical
what is the role of pilocarpine
causes pupil constriction = increasing iridocorneal angle
how is acetazolamide given
IV
what is the role of acetazolamide
stops aqueous humour production
in addition to 3 key medications, what may be offered for acute angle-closure glaucoma
anti-emetic
analgesia
what is the long-term management of acute angle-closure glaucoma
YAG laser peripheral iridectomy
what does laser peripheral iridectomy involve
Hole is cut into the iris at 12’O-clock enabling drainage
what is the complication of angle-closure glaucoma
increase pressure can cause occlusion of central retinal artery or vein leading to blindness
define open-angle glaucoma
optic neuropathy with death or retinal ganglion cells and their axons
why is raised IOP not part of definition in open-angle glaucoma
as open-angle glaucoma can occur with both raised and normal IOP
what is the second most common cause of blindness worldwide
open-angle glaucoma
how does incidence of chronic glaucoma change with age
increases
what age does chronic glaucoma usually affect
> 40
what are the four non-modifiable risk factors for open-angle glaucoma
- FH
- Age
- Afro-carribean
- Myopia (short-sighted)
what are the 4 modifiable risk factors for open-angle glaucoma
- DM
- Corticosteroids
- HTN
- Raised IOP
why is open-angle glaucoma often referred to as asymptomatic
As the visual field defect happens so progressively that patients often don’t notice it
what is the ‘triad’ of signs/symptoms in angle-open glaucoma
- Raised IOP
- Visual field defect
- Cupping
what is raised IOP
IOP >21
why is cupping of the optic disc seen
Due to death of retinal ganglion cells in the neuroretinal rim
what visual loss happens in open-angle glaucoma first
Peripheral field loss - usually of superior and nasal fields
what is spared in open-angle glaucoma
Central vision
how does increase IOP in open-angle glaucoma affect the optic nerve
Raised IOP causes atrophy of the outer rim - loss of peripheral vision and then causes further damage causes loss of central vision
Explain optic disc cupping
Loss of disc substance. Makes cup appear larger. Which deepens, vessels emerging appear to have a ‘break’. Notching of the cup and dis may occur. The vessels are displaced nasally causing loss of superior and nasal fields.
What is first-line to investigate open-angle glaucoma
automated perimetry - to look at visual field loss
How can glaucoma be identified on automate perimetry
more than 3-locations outside of the individuals visual field
Explain visual field loss on open-angle glaucoma
- Starts superior, nasal field loss
- Progresses to, temporal field loss
- Finally, central field loss
Is open-angle glaucoma bilateral or unilateral
Bilateral. However, visual field defects may not be symmetrical
What is second-line investigation for open-angle glaucoma
Slit lamp
What are 4 features of open-angle glaucoma on slit lamp
- Increased disc to cup ratio
- Pale optic disc
- Bayonneting of vessels
- Other - haemorrhages
what causes optic disc cupping
Destruction of retinal ganglion cells - making disc appear smaller
what is the optic disc to cup ratio in open-glaucoma
> 0.7
why is the optic disc pale in open-angle glaucoma
Due to atrophy of optic disc
what is bayoneting of vessels
As vessels dissapear into the cup - they appear to have breaks. More common inferiorly
where does bayonetting of vessels usually occur
inferior cup
what is third line investigation of glaucoma
tonometry
what does tonometry look at
IOP
how does tonometry present in open-angle glaucoma
> 21mmHg
why is screening for open angle glaucoma recommended
As it is usually asymptomatic - so individuals are unaware
what does screening involve
tonometry, visual dields, optic disc exam
what do NICE recommend for screening
individuals over 40 with a first-degree relative should receive screening
once diagnosed, how often are individuals followed up
every 6m to deter damage
explain aims of management in open-angle glaucoma
treatment will not improve vision, but it will prevent further deterioration.
What two medications are given for open-angle glaucoma
- Prostaglandin analogue
2. B-blocker
What prostaglandin analogue is given in open-angle glaucoma
Lantoprost
What is the role of lanoprost
Increases outflow
Apart from B-blockers, what two drugs are possible alternatives
Sympathomimetics
Carbonic anhydrase inhibitors
If medication is ineffective, what treatment is considered
Surgery
What two surgical procedures can be offered for open-angle glaucoma
- Trabeculoplasty
- Trabeculectomy
What is trabeculoplasty
Surgical procedure to increase outflow of aqueous humour
What medication is first-line in open-angle glaucoma
Prostaglandin analogue
What are the roles of prostaglandin analogues
Decreases aqueous humour production
What are 4 side-effects of prostaglandin analogues
- Longer eyelashes
- Brown pigmentation iris
- Peri-orbital pigmentation
- Red eye
What is the MOA of B-blockers in glaucoma
Reduce production of aqueous humour
What are 3 side-effects of topical b-blockers
- Dry eyes
- Corneal anaesthesia
- Tachycardia
In what patients should topical B-blockers be given with care and why
HF and asthmatics = absorbed straight into circulation
What is the role of carbonic anhydrase inhibitors
Decrease production aqueous humour
What are side effects of carbonic anhydrase inhibitors
Lassitude
Dyspepsia
Hypokalaemia
Parasthesia
When are carbonic anhydrase inhibitors contraindicated
Pregnancy
What is a side effect of sympathomimetics
Red-eye with loss of vision
When should sympathomimetics definitely not be used and why
Angle-closure glaucoma. As sympathomimetics will cause dilation of the pupil - which will further obstruct trabecular meshwork
What else needs to be considered in management of chronic glaucoma
DVLA contacted
What is the uvea
middle-layer of the eye