Pathology Flashcards
(34 cards)
What name is given to the outer layer of the lens?
Epithelium
What is special about the epithelium of the lens in comparison to other epithelia in the body?
Epithelium of the lens has no potential for malignancy
How is cataracts defined?
Opacification of the lens due to clouding or scratches
What percentage of blindness worldwide is caused by cataracts?
50%
What are the main causes of cataracts?
Age related degeneration of the nerve fibres
=> opacification
Sun damage (UVB)
What factors can increase the risk of developing cataracts?
Hypertension Smoking Post-operative OR Trauma Genetic/Metabolic disorder Diabetes
How does diabetes cause cataracts?
Changes the osmotic pressure
=> fluid content in lens changes and causes nerve fibres to degenerate
What is Glaucoma?
Abnormal increase in pressure behind the eyes
Either too much humour produced, or not being drained quickly enough
Describe the course of aqueous fluid in the anterior chamber of the eye
Ciliary Body Between Lens and Iris Over top of Iris Trabecular Meshwork Canal of Schlemm
What structures in the eye are damaged as a consequence of glaucoma?
Optic disc and nerve
Describe the difference between Primary Open Angled Glaucoma and Angle Closure Glaucoma?
Primary Open Angled = poor drainage through trabecular meshwork and in the Canal of Schlemm
Angle Closure = Fluid cant get through to meshwork due to obstruction (e.g. iris)
What investigation is used in diagnosis of primary open angles glaucoma?
Applanation Tonometry (Air puff test) Depending on the eyes resistance to the air, the intra-ocular pressure can be measured
Angle Closure Glaucoma usually presents with a slow onset that is often asymptomatic. TRUE/FALSE
FALSE
Primary Open Angled Glaucoma presents this way
Angle closure presents more acutely:
- red eye
- vision loss
- headaches
- Nausea and vomiting
What treatment is used when Angle Closure Glaucoma presents as an emergency?
Laser treatment
What is the aim of Primary Open Angled Glaucoma treatment?
Therapies are aimed at slowing production of aqueous humour or widening the canal to promote drainage
What types of drops are prescribed in Primary Open Angled Glaucoma?
Beta Blocker drops (slow aqueous humour production)
=> e.g. Timolol
Carbonic Anhydrase Inhibitor Drops (slow aqueous humour production) => e.g. Acetazolamide
Prostaglandin drops (aid drainage of humour) => e.g. Latanoprost
What sign is often seen in the optic disc of patients with glaucoma?
“Cupping”
Edges = rolled
Centre = depressed
What is papilloedema?
Bulging of the optic disc in the centre (opposite of cupping)
Due to raised intra-cranial pressure
What is the difference between episcleritis and scleritis?
Episcleritis - just on surface (superficial and self-limiting)
Scleritis - More severe with pain on movement - thought to be of autoimmune origin
Name the two types of age related macular degeneration (ARMD)
Dry = no vascular proliferation (leaky blood vessels) Wet = Vascular proliferation/ leaky vessels =>visual loss
What is thought to cause ARMD?
Not well known => Underlying inflammatory process
Accumulation of by-products
=> (Drusen - protein/lipid/inflammatory mediators)
What is thought to mediate wet ARMD and why is this useful?
Vascular endothelial growth factor (VEGF)
=> can aim monoclonal antibody treatments at this source
How does blurred vision relate to diabetes?
This is often a presenting complaint in Type 1 Diabetes Mellitus if patients are otherwise asymptomatic
What sign can be seen in the pupils of a diabetic patient?
Argyll-Robertson sign
Accommodates (can move far to near) but doesn’t react (constrict/vasodilate)
