Pathology Flashcards
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)
How is cataracts developed in diabetes?
- Hyperglycaemia causes increased sugar content in the lens
- Glucose converted to sorbitol
- Alters the osmotic gradient and causes swelling and fibre disruption
How do diabetic patients develop glaucoma?
New vessel formation (due to hypoxia) obstructs the angle and pressure is allowed to build
Describe Diabetic retinopathy
Poor vessel function leads to leaky vessels and small aneurysms
The eye then begins to form new vessels which are fragile!
What treatment can be used to remove the newly forming vessels in glaucoma related diabetic retinopathy?
Laser treatment
coagulates the new vessels which are forming
What do CRAO and CRVO stand for?
Central Retinal Artery Occlusion
Central Retinal Vein Occlusion
What is the most common sight for thromboembolic disease to pass onto the eye?
Common carotids
A “transient ischaemic attack” can occur in the eye but goes by a different name, what is this?
Amaurosis Fugax
What type of arteritis is important to look for in the eyes?
Giant Cell
What tumours can arise in the eyelid?
Basal Cell Carcinoma
Squamous Cell Carcinoma
Melanoma
(Due to sun exposure)
Where else in relation to the eye can a primary melanoma present?
Retina (due to melanocytes being present here)
