Eye Pathology Flashcards
Describe conjunctivitis
Inflammation of the conjunctiva
Often caused by viruses
Eye feels uncomfortable and gritty. Often have tearing of the eye
Is highly contagious -> easily spreads
Treatment is usually reassurance
Describe subconjunctival haemorrhage
Causes red eye
Occurs when one of the small conjunctival blood vessels ruptures resulting in blood escaping and becoming visible under conjunctival layer
Are common, not painful
Treatment is reassurance that is will resolve
Describe uveitis
Serious condition presenting as acutely painful red eye
Uveitis - inflammation of the choroid layer
Typically associated with autoimmune conditions
Requires immediate referral to ophthalmology
Why do people have colour blindness
People have colour blindness because they have an absence of dysfunction of one of the colour cones in the eye
Three cones: red, blue and green
What is glaucoma and what are the two types
Glaucoma - optic neuropathy due to raised intraocular pressure. Can occur as we get older because of obstruction to the drainage of aqueous humour
Open-angle glaucoma
Closed-angle/acute closed-angle glaucoma
Describe open-angle glaucoma
Most common type and is chronic
Caused by blockage within trabecular meshwork - meshwork deteriorates as we age -> have increased intraocular pressure and glaucoma
Develops painlessly and insidiously over time -> difficult to pick up
Signs: cupping of optic disc, visual field loss
Treatment: topical agent that reduces production of aqueous humour and/or increases its drainage
Describe closed-angle glaucoma
Is acute and less common
Caused by narrowing of the irido-corneal angle resutling in the trabecular meshwork being blocked off -> have rise in intraocular pressure
Presents with: painful red eye, blurred vision, halos around orbit, nausea, vomiting, irregular oval-shaped pupil
Eye is hard and tender to palpate
Opthalmic emergency - initially managed medically using diuretics and muscarinic eye drops to decrease intraocular pressure
Treat by making a hole in iris to relieve pressure
What is an orbital blow out fracture and what causes it
Fracture of the floor of the orbit
Caused by a sudden increase in intraorbital pressure, e.g. something getting within orbital rim and increasing pressure in orbit
What is the typical history of a paitent with an orbital blow out fracture
Periorbital swelling and pain
Diplopia - worse on vertical gaze. Fracture site can trap structures, tethering muscles which can prevent upwards gaze on affected side
Anaesthesia on affected side - damage to infraorbital branch of maxillary nerve
Eyes appear sunken due to prolapse - prolapse can cause bleeding into the maxillary sinus
What is periorbital cellulitis and what is it caused by
Also known as pre-septal cellulitis
Periorbital cellulitis is infection occuring within eyelid tissue, superficial to orbital septum -> only involves subcutaneous tissues of eyelid
Is secondary to superficial infections or bacterial sinusitis in children
Ocular function unaffected
What is orbital cellulitis, what are the symptoms and how is it treated
Infection within the orbit, deep to the orbital septum
Involves orbital tissue/fat and extraocular muscles
Symptoms: proptosis/exopthalmos, reduced eye movements, +/- painful eye movements, reduced visual acuity
Treated with high dose IV antibiotics and surgical drainage
What complications can orbital cellulitis cause
Infection can spread intracranially to cause cavernous sinus thrombosis or meningitis
Can involve optic nerve
Describe the causes of blurred vision and the test that can help determine the cause of blurred vision
Transparency of structures anterior to retina being affected -> light cannot reach focal point. E.g. cataracts
Decreased ability of structures to refract light. E.g. shape of eyeball, presbyopia, irregularity of corneal suface (astigmatism)
Pathology to the retina or optic nerve. E.g. retinal detachment, age-related macular degeneration, optic neuritis
Can see if acuity improves with pin-hole test - light does not need to be refracted to be brought to macula with pin-hole test -> can see if refraction error or optic nerve/retina error
Describe CN III palsy
CN III palsy affected LPS, most extraocular muscles and PSN function to sphincter pupillae
Patient has down and out eye position, dilated pupil and possibly diplopia
Either:
Compressive lesion involving the pupil - presence of pupil involvement raises concern. E.g. raised ICP, tumour, aneurysm
Vasculopathic lesion sparing the pupil. E.g. diabetes, hypertension
Describe CN IV palsy
CN IV innervates superior oblique -> plasy causes eyeball to be extorted, slightly elevated and adducted
Patient may tilt head to compensate for extortion
Worsening diplopia, especially on looking down and medially
