Pathology Flashcards
Describe the histology of the lens
Largely enucleate with cells that elongate to produce fires
What is the main pathology of the lens?
Cataracts
What are cataracts?
Opacification’s within the lens (50% of all causes of blindness worldwide)
In the UK what is the main cause of cataracts?
Age
How do cataracts occur due to ageing?
As the lens epithelium matures eventually the cell contents are replaced and the nucleus disappears leaving a fibre within the lens. Alteration in reparative mechanism means that with age the fibres get stuck in a cross linked structure.
What increases the likelihood of cataracts?
Cumulative UVB damage
Other than age name some cases of cataracts
Hypertension, smoking, post-op, trauma, metabolic disease, genetics, diabetes
How does diabetes cause cataracts?
Changes to osmotic pressures alter the fluid content and damage fibres
What is glaucoma?
Abnormal increase in pressure in the eye due to a blockage in the drainage system
What does the increased pressure relate to?
Vitreous fluid and aqueous humour
Describe the physiological drainage of fluid
Through the trabecular meshwork and out schlemm’s canal
Where does glaucoma have the biggest impact?
Optic nerve and disc
Name two types of glaucoma
Open angled
Angle closure
Describe the presentation and cause of open angled glaucoma
Due to poor drainage through the meshwork
Presents with slow onset often asymptomatic
What does treatment of glaucoma involve and aim to do?
Aims to slow down the disease by drugs that widen the canal
Describe the presentation and cause of angle closure glaucoma
Drainage is patent but the fluid cannot reach it as the lens is in contact with the iris.
Emergency - patient will be acutely unwell, red eye, visual loss and headache with nausea and vomiting
How is angle closure glaucoma treated?
Laser surgery
How can raised ICP present in the disc?
Cupping - rolled edges and a depressed centre
Define papilloedema
Swelling of the optic nerve/disc due to increased ICP
What are scleritis/episcleritis?
Inflammation of the sclera
Describe scleritis
Rare but severe, associated with pain on movement and may have an underlying autoimmune aetiology
What autoimmune diseases are associated with scleritis?
SLE, HLA B27 conditions
Describe episcleritis
Superficial and self limiting with no clear cause
What does ARMD stand for?
Age related macular degeneration
What two types is ARMD divided into?
Dry - no significant vascular proliferation
Wet - vascular proliferation
Describe dry ARMD
Accumulation of drusen which may become calcified presents with reduced acuity, partial visual loss or distorted vision
Describe wet ARMD
Neovascularisation in choroid mediated by VEGF - new vessels are fragile and leaky which leads to haemorrhage and visual loss
How can wet ARMD be treated?
Monoclonal antibodies to VEGF
What can sometime be visible when looking at the eye in ARMD?
Grey membrane
Name two changes that can occur in diabetics in the pupils
Argyll Roberson (accommodate but don't react) Peripheral Neuropathy
Why do diabetics get cataracts?
Increased sugar in the lens, glucose is converted to sorbitol and this altered gradient leads to swelling and fire disruption
What type of glaucoma is a rare late presentation in diabetics?
Rubeotic glaucoma - new vessel formation obstructs angle
Describe retinopathy
Complex mechanisms lead to poor functioning vessels which are leaky causing aneurysms
What happens in severe retinopathy?
New vessels form
What is maculopathy?
Damage to the retina as a result of retinopathy causes oedema and ischaemia which can lead to visual loss
When looking at the eye what might signify a patient has had laser surgery?
Lots of well demarcated light dots
Name two types of occlusion disease
Central retinal artery occlusion
Central retinal vein occlusion
What tumours can present in the eye?
BCC, SCC, Melanoma
In terms of tumours what must you be careful of in the eye?
Retinal melanoma may look like a mole
Beware of metastatic disease
