Opthalmology Flashcards
What causes glaucoma?
Optic nerve damage that is caused by a significant rise in intraocular pressure due to a blockage in aqueous humour trying the escape the eye
What are the 2 types of glaucoma?
Open angle and closed angle
Where is aqueous humour produced?
The ciliary body
What is normal intraocular pressure?
10-21 mmHg
What happens in acute angle-closure glaucoma?
The iris bulges forward and seals off the trabecular meshwork (where the aqueous humour drains) which leads to a continuous build up of pressure. This is an ophthalmology emergency
What is “cupping” in glaucoma?
caused by increased in pressure in the eye. In the centre of the optic disc is an optic cup. When there is raised intraocular pressure the indent becomes larger and the cup becomes wider and deeper. A cup greater than 0.5 the size of the optic disc is abnormal
How does open angle glaucoma present?
Affects peripheral vision first which gradually closes in until it becomes tunnel vision
Fluctuating pain, headaches, blurred vision and halos of light appearing, especially at night
How can intraocular pressure be measured?
Non-contact tonometry (the puff of air test)
Goldmann applanation tonometry (gold standard)
How is glaucoma diagnosed?
Goldmann applanation tonometry
Fundoscopy
Visual field assessment
When is treatment commenced in glaucoma?
When the pressure is greater than 24mmHg
What is the management for open angle glaucoma?
Prostaglandin analogue eye drops - lantanoprost
Beta-blockers (timolol) reduce the production of aqueous humour
Carbonic anhydrase inhibitors (dorzolamide)
Trabeculectomy
What are the notable side effects of prostaglandin analogue eye drops?
Eyelash growth
Eyelid pigmentation
Iris pigmentation (browning)
Which medications can precipitate acute angle-closure glaucoma?
Adrenergic medications such as noradrenalin
Anticholinergic medications such as oxybutynin and solifenacin
Trycyclic antidepressants such as amitriptyline
How does acute angle-closure glaucoma present?
Severely painful red eye
Blurred vision
Halos around lights
Associated headache, nausea and vomiting
What does an eye with acute angle-closure glaucoma look like?
Red-eye Teary Hazy cornea Decreased visual acuity Dilatation of the affected pupil Fixed pupil size Firm eyeball
How should acute angle-closure glaucoma be managed?
Lie patient on back without pillow
Give pilocarpine eye drops (2% blue eyes, 4% brown eyes)
Oral or IV acetazolamide which is a carbonic anhydrase inhibitor
Laser iridotomy is the definitive treatment
What is the key finding associated with macular degeneration which is found on fundoscopy?
Drusen
What are the 2 types of age related macular degeneration?
Dry (90%) and Wet (10%)
Wet has worse prognosis
What is the presentation of macular degeneration?
Gradual worsening of central visual field loss
Reduced visual acuity
Crooked or wavy appearance to straight lines
How can macular degeneration be investigated?
Snellen chart
Scotoma (central patch of visual loss)
Amsler grid test (crooked straight lines)
Fundoscopy (drusen)
What is the management for dry macular degeneration?
Avoid smoking
Control blood pressure
Vitamin supplementation
What is the management of wet macular degeneration?
Anti- VEGF medications injected directly into the vitreous chamber.
What causes diabetic retinopathy?
The retina are damaged by prolonged exposure to hyperglycaemia. Vessels become leaky leading to microaneurysms and venous beading
Damage to nerve fibres causes fluffy white patches called cotton wool spots
What are the two categories of diabetic retinopathy?
Proliferative and non-proliferative