Opthalmology Flashcards
Painful reduced vision in one eye with vomiting and halos around lights
Acute closed angle glaucoma
What is the treatment for acute closed angle glaucoma
i. acute
ii. defintive
Treatment:
ACUTE:
Timolol= a beta blocker, and
Apraclonidine= an alpha agonist,
both used to block production of aqueous humor and promote pupillary miosis.
Additionally, systemic carbonic anhydrase inhibitors, such as acetazolamide, can be used to prevent secretion of aqueous humor.
DEFINITIVE:
-Laser iridotomy to create an opening in the iris, allowing drainage of the posterior chamber and an increase in the anterior chamber angle.
Exacerbating symptoms for glaucoma
Glaucoma may be exacerbated by entrance into a dark room (e.g. movie theater) or reading in dim light where pupillary dilation is the normal response.
Gold standard diagnostic tool for glaucoma
Gonioscopy, performed by an ophthalmologist, is the gold standard for diagnosis of acute angle closure glaucoma.
What are the causes of loss of red reflex
The best-known causes of loss of the red reflex are cataracts
(opacification of the lens)
and
retinoblastoma (a rare form of cancer involving cells of
the retina in children).
Differentiate bacterial and viral conjunctivitis
Bacterial is unilteral, viral is bilateral
Bacterial is thick discharge, viral is watery
Bacterial is reduced vision, viral is normal
Bacterial cause includes STD so may have urethritis/bacterial discharge from vagina,
Viral may have fever and lypmphadenopathy
Painless visual imparment with glare and halos around lights?
Noticed eye has gone white
Cataracts.
Reduced red reflex and clouding of lens
Define cataracts
Opacification of the lens of the eye
Explain the aetiology / risk factors of cataracts
Majority idiopathic age related.
Secondary causes:
Local- previous eye trauma, uveitis, intraocular tumours
Systemic- diabetes, metabolic disorders, drugs (steroids), x-ray/UV radiation, Down’s syndrome, systemic disease
Congenital: CONGENITAL RUBELLA SYNDROME
Summarise the epidemiology of cataracts
35% of >65 year old people have visiaully impairing cataracts in at least one eye
Recognise the presenting symptoms of cataracts
Gradual onset PAINLESS loss of vision
Glare from bright lights
Vision may worsen in bright light (especially with central lens opacity)
Monocular diplopia/haloes around lights
Can read without glasses
Ambylopia or nystagmus in infants
Recognise the signs of cataracts on physical examination
Loss of red reflex
Hazy lens appearance
Reduced visual acuity
Identify appropriate investigations for cataracts and interpret the results
Biometry:
To assess appropriate intraocular lens implant.
Other unnecessary unless occurring at early age or associated with systemic disease
Define glaucoma
Optic neuropathy with typical field defect usually associated with ocular hypertension (intra-ocular pressure, IOP>21mmHg).
Damages optic nerve and can lead to blindness
Explain the aetiology / risk factors of glaucoma
What is the anterior vs posterior chamber of the eye. What is the vitreous chamber
See below for normal aqeous humor physiology
Blockage in the pathway through which aqeous humour is drained.
Anterior and posterior chamber are both parts of the anterior segment.
Anterior chamber: from cornea to iris.
Posterior chamber: from iris to lens
Vitreous chamber: from lens to back of eye.
Due to blocked drainage, the pressure within the fixed anterior chamber builds up, causing intraocular hypertension.
This high pressure affects all part of the eye, including the optic nerve (even though the high pressure is in the anterior chamber).
As optic nerve gets damaged, glaucoma leads to vision loss.
- OPEN ANGLE GLAUCOMA (most common)
- CLOSED ANGLE GLAUCOMA.
Summarise the epidemiology of glaucoma
Prevalence 1 % in over 40 years, 10 % in over 80 years (POAG). Third most common cause of blindness worldwide
Recognise the presenting symptoms of glaucoma
ACAG: Painful red eye, vomiting, impaired vision, haloes around lights.
POAG: Usually asymptomatic, peripheral visual field loss may be noticed.
See below for explanations
Recognise the signs of glaucoma on physical examination
Primary causes: acute closed angle glaucoma (ACAG), primary open angle glaucoma (POAG)
ACAG:
-Red eye, hazy cornea, loss of red reflex, fixed and dilated pupil, eye tender and hard on palpation, cupped optic disk, visual field defect (arcuate scotoma), moderately raised IOP, blurred vision
POAG:
-Optic disk may be cupped. Usually no signs.
Secondary causes:
-Trauma, uveitis, steroids, rebeosis iridis (diabetes, central retinal vein occlusion)
Congenital:
-Bupthalmos
Identify appropriate investigations for glaucoma and interpret the results
First thing, POAG is a diagnosis of exclusion. You must do the following things.
Firstly: Goldmann applanation tonometry (standard examination to measure ocular pressure, will be >30 in primary)
Gold standard: Gonioscopy to assess the angle
Perimetry: for arcuate scotoma (early) and tunnel vision (late)
What is the normal secretion and drainage of aqeous fluid
Aqeous humor secreted into posterior chamber from the ciliary epithelium. It then travels past the iris, into the anterior chamber, and is drained via the trabecular meshwork into the canal of schlemm, which then allows the fluid to drain into aqeous veins, part of the episcleral venous system.
What is the cause of open angle glaucoma
What is the history
The angle between cornea and iris is open.
The drainage system itself slowly becomes clogged, leading to gradual build up of pressure.
This causes the outer rim of the optic nerve to atrophy. As damage continues, eventually the centre of vision will be lost as well
History:
Peripheral loss of vision –> central vision loss
What is the cause of close angle glaucoma
What is the history
Angle between iris and cornea is too small, so the passage for aqeous humor is too small.
This is because the lens gets pushed against the iris, and the iris then is pushed towards the cornea, impairing the drainage angle
There is a rapid build up of pressure within the eye
Hx: Abrupt onset eye pain Redness Blurry vision Headaches Nausea Visual halos
Causes of abnormally large pupil
1) Third nerve palsy
2) Pharmacological
3) Acute glaucoma
4) Unilateral fixed dilated pupil (raised ICP and coning)
What is optic neuritis and what would the next investigation be
Optic neuritis refers to inflammation of the optic nerve caused by demyelination.
Diagnosis is usually clinical- unilatral deterioration in visual acuity and colour perception + PAIN on eye movement (see MS)
However, imaging may be required to exclude alternative causes of optic nerve dysfunction and also to assess the risk of future episodes of CNS demyelination.
Best investigation is MRI as it can show characteristic lesions of MS and demyelination
