GLAUCOMA Flashcards
What is the main cause of glaucoma?
Increased intraocular pressure
What determines the intraocular pressure?
The balance between the rate of aqueous humour production by the ciliary body and the rate of clearance by the trabecular meshwork.
What are the two main types of primary glaucoma?
Primary open angle glaucoma (POAG)
Primary angle closure glaucoma (PACG)
What is the most common type of primary glaucoma in most races?
Primary open angle glaucoma (POAG)
What is the normal range of intraocular pressure?
10-22 mmHg
What is the mechanism of ganglion cell damage by high intraocular pressure?
Combination of mechanical distortion and localised disturbance of vascular supply.
What is the pattern of damage in term of visual loss?
Sensitivity to light in the periphery is lost first. This is followed by more central vision being affected until the majority is eventually completely lost.
Glaucoma is the most common cause of irreversible blindness
What percentage of the ganglion cells will have been irreversibly damaged before visual field testing will pick up the pathology?
30-50%
What is the main mechanism behind primary open angle glaucoma?
Idiopathic age-related changes to the trabecular meshwork
What group of patients is most commonly affected by open angle glaucoma?
Those of African origin (5 times more likely than caucasian)
What are the risk factors for developing open angle glaucoma?
Older age
Raised IOP
Affected first degree relative
African origin
Myopia
Thin cornea
Larger optic disc
Pupillary dilatation
What is the main symptom for open angle glaucoma?
Progressive visual loss - often found using objective tests rather than patient subjective reporting
What intraocular pressure is typically reached to cause acute angle closure glaucoma?
65 mmHg
What is the instrument used to measure the intraocular pressure?
The Goldmann tonometer
What are the symptoms of acute angle closure glaucoma?
Headache
Severe pain in the eye or over the brow
Photophobia
Loss of vision
Nausea and vomiting
Seeing haloes around lights
Symptoms worse with mydriasis (dilation of the pupil - eg watching TV in dark room)
On examination of someone with acute angle glaucoma, what signs might you expect to pick up?
Severely reduced acuity in the affected eye (often worse than 6/60)
Red eye
Hazy cornea (due to oedema)
Oval pupil
Semi-dilated non reactive pupil
Cupping of the disc (increased cup-to-disc ratio)
What are the risk factors for developing acute angle closure glaucoma?
Elderly Hypermetrope (long sighted) Use of topical steroids (despite being a treatment can raise the IOP)
What is the window of time between extremely elevated intraocular pressure and the retina becoming so ischaemic that it dies?
4 hours
How do you medically treat acute angle closure glaucoma?
- Carbonic anhydrase inhibitor - i.v acetazolamide
- Topical steroids - dexamethasone
- Topical cholinergic (miotics) - pilocarpine
- Topical beta-blockers - timolol, levobunolol
- Topical alpha-adrenergic agonists - brimonidine, apraclonidine
- Carbonic anhydrase inhibitor can be given topically but DO NOT do this if IV has already been given - dorzolamide or brinzolamide
- Topical prostagladin analogues - latanoprost, travoprost
How does the concentration of pilocarpine differ based on the colour of the patient’s iris?
Blue or green - 2%
Brown - 4%
What are the laser procedures that can be done to try and help relieve the pressure caused by acute angle closure glaucoma?
Laser peripheral iridotomy - hole in the iris allows movement between the posterior and anterior chamber
Argon laser iridoplasty - upgrade of laser PI where this time a ring of iris is thinned
Laser trabeculoplasty - directly treats the trabecular meshwork
Trans-scleral diode laser ciliary body ablation - reduced aqueous humour production. Only really used in patients who cannot undergo surgery.
What are the surgical procedures that can be done to try and help relieve the pressure caused by acute angle closure glaucoma?
Trabeculectomy - hole is made through the sclera into the anterior chamber. Tubes may be used to help the drainage through the hole.
What are the medical treatment options for open angle glaucoma?
Prostaglandin analogues (e.g. Latanoprost)
Beta-blockers (e.g. Timolol)
Sympathomimetics (e.g. brimonidine, an alpha2-adrenoceptor agonist) - Reduces aqueous production and increases outflow
Carbonic anhydrase inhibitors (e.g. Dorzolamide) - Reduces aqueous production
Miotics (e.g. pilocarpine, a muscarinic receptor agonist)
What is the first line treatment for open angle glaucoma?
Prostaglandin analogues - latanoprost
Name the drug:
Adverse effects include brown pigmentation of the iris
Latanoprost
A mother brings her 8-week-old child in for review. Since birth his right eye has been watering. His symptoms have got worse over the past few days after he picked up a mild viral illness. Clinical examination is unremarkable. What is the most appropriate action?
Refer urgently to ophthalmology
Teach nasolacrimal duct massage
Perform a depression screen on the mother
Advise mother to clean inner eyelids and use warms compresses
Refer routinely to ophthalmology
Teach nasolacrimal duct massage
A 70-year-old man is investigated for blurred vision. Fundoscopy reveals drusen, retinal epithelial and macular neovascularisation. A diagnosis of age related macular degeneration is suspected. What is the most appropriate next investigation?
Vitreous fluid sampling
MRI orbits
Ocular tonometry
Fluorescein angiography
Kinetic perimetry
Fluorescein angiography
If neovascularisation is present fluorescein angiography is performed
A 70-year-old woman presents with loss of vision in her left eye. For the past two weeks she has painful frontal headaches and has been feeling generally lethargic. On examination visual acuity is 6/9 in the right eye but on the left side only hand movements can be made seen. Fundoscopy of the left side reveals a pale and oedematous optic disc. What is the most likely diagnosis?.
Acute angle closure glaucoma
Central retinal artery occlusion
Multiple sclerosis
Methanol poisoning
Temporal arteritis
Temporal arteritis
This patient has likely developed anterior ischemic optic neuropathy on the left side
Each one of the following is a cause of a mydriatic pupil, except:
Third nerve palsy
Atropine
Holmes-Adie pupil
Argyll-Robertson pupil
Traumatic iridoplegia
Argyll-Robertson pupil
Argyll-Robertson pupil is one of the classic pupillary syndrome. It is sometimes seen in neurosyphilis and is often said to be the prostitute’s pupil - accommodates but doesn’t react. Another mnemonic used for the Argyll-Robertson Pupil (ARP) is Accommodation Reflex Present (ARP) but Pupillary Reflex Absent (PRA)
Features
- small, irregular pupils
- no response to light but there is a response to accommodate
Causes
- diabetes mellitus
- syphilis
Which one of the following is associated with heterochromia in congenital disease?
Holmes-Adie pupil
Third nerve palsy
Sixth nerve palsy
Argyll-Robertson pupil
Horner’s syndrome
Horner’s syndrome
Which one of the following best describes the action of latanoprost in the management of primary open-angle glaucoma?
Carbonic anhydrase inhibitor
Reduces aqueous production + increases outflow
Opens up drainage pores
Increases uveoscleral outflow
Reduces aqueous production
Increases uveoscleral outflow
Which one of the following is least associated with the development of optic atrophy?
Ataxic telangiectasia
Longstanding papilloedema
Multiple sclerosis
Glaucoma
Retinitis pigmentosa
Ataxic telangiectasia
A 71-year-old with a history of type 2 diabetes mellitus and hypertension presents due to the sensation of light flashes in his right eye. These symptoms have been present for the past 2 days and seem to occur more at the peripheral part of vision. There is no redness or pain in the affected eye. Corrected visual acuity is measured as 6/9 in both eyes. What is the most likely diagnosis?
Change in shape of eye secondary to variations in blood sugar
Primary open angle glaucoma
Vitreous detachment
Normal phenomenon in diabetic retinopathy
Normal phenomenon in healthy eyes
Vitreous detachment
Flashes and floaters are symptoms of vitreous detachment. The patient is at risk of retinal detachment and should be referred urgently to an ophthalmologist
Vitreous haemorrhage
- Causes: diabetes, bleeding disorders
- Features may include sudden visual loss, dark spots
Which of the following is not a recognised feature of Horner’s syndrome?
Mydriasis
Heterochromia in congenital Horner’s
Ptosis
Enophthalmos
Anhydrosis
Mydriasis
Ptosis + dilated pupil = third nerve palsy
Ptosis + constricted pupil = Horner’s
Which one of the following statements regarding the Holmes-Adie pupil is incorrect?
May be associated with absent ankle/knee reflexes
Bilateral in 80% of cases
It is a benign condition
Slowly reactive to accommodation but very poorly (if at all) to light
Causes a dilated pupil
Bilateral in 80% of cases
The Holmes-Adie pupil is unilateral, rather than bilateral, in 80% of patients
What is the drug used in the treatment of open angle glaucoma that both reduces aqueous production and increases outflow?
Timolol
Pilocarpine
Brimonidine
Dorzolamide
Latanoprost
Brimonidine
