Ophthalmology Flashcards
What are the 3 layers of the eyeball?
- Fibrous
- Vascular
- Inner
What does the inner layer of the eyeball include?
The retina
What are the anterior and posterior chambers of the eye?
- 2 fluid filled chambers in the eye
- They are filled with clear aqueous humour that protects the eye
- This is drained via the trabecular meshwork
- Obstruction of this drainage results in glaucoma
What is the main fluid part of the eyeball?
Vitreous body
What is the name and function of CN II
- Optic
- Sight
What is the name and function of CN III?
- Oculomotor
- Innervation of IO, MR, SR, IR muscles
- Elevation of the eyelid
- Miosis and accommodation
What is the name and function of CN IV?
- Trochlear
- Innervation of SO muscle
What is the name and function of CN VI?
- Abducens
- Innervation of LR muscle
What is the name and function of CN VII?
- Facial
- Closure of eyelids
- Lacrimation
What vessels provides arterial blood supply to the eyeball? What is a key branch and why?
- Ophthalmic artery
- Central artery of the retina
- Occlusion of this can quickly result in blindness
What vessels carry out venous drainage of the eyeball?
Superior and inferior ophthalmic veins
What neurotransmitter and division of the autonomic nervous system cause pupil constriction?
- Parasympathetic
- Acetylcholine
What neurotransmitter and division of the autonomic nervous system cause pupil dilation?
- Sympathetic
- Adrenaline
What is considered normal vision? What do the numbers mean? What would indicate better and worse vision?
- 6/6 (in america this = 20/20)
- It means the patient can read something at 6 metres that the average person can read at 6 metres
- 6/9 (worse vision) - the patient can read something at 6 metres that the average person can read at 9
- 6/4 (better vision) - the patient can read something at 6 metres that the average person can read at 4
What is diabetic retinopathy
Where blood vessels in the retina are damaged by hyperglycaemia
What is seen in diabetic retinopathy when visualising the retina?
- Microaneurysms
- Venous beading
- Neovascularisation
- Blot haemorrhages
- Hard exudates (lipid deposits in the retina)
- Cotton wool spots (sign of nerve fibre damage)
Complications of diabetic retinopathy
- Retinal detachment
- Vitreous haemorrhage
- Optic neuropathy
- Cataracts
What is glaucoma?
Optic nerve damage caused by raised intraocular pressure
What are the 2 types of glaucoma?
- Open angle glaucoma
- Acute angle closure glaucoma
Which of the types of glaucoma is an ophthalmic emergency?
Acute angle closure glaucoma
What happens in open angle glaucoma?
- There is an increase in resistance in the trabecular meshwork
- This makes is more difficult for aqueous humour to flow through the meshwork and exit the eye
- The pressure fluids slowly and results in slow onset glaucoma
What are features of open angle glaucoma?
- Asymptomatic for a long time
- Reduced peripheral vision
- Tunnel vision
- Gradual onset of fluctuating pain, headaches, blurred vision, halos around lights
What is the first line management of open angle glaucoma?
- Prostaglandin analogue eye drops (e.g. latanoprost)
- Increase uveoscleral outflow
What happens in acute angle closure glaucoma?
- The iris bulges forward and seals off the trabecular meshwork
- This prevents aqueous humour from being able to drain away
- This leads to a continual build-up of pressure.