Common Conditions of the Eye Flashcards
What is the consequence of the bony orbit having very thin walls?
Can get herniation of contents into surrounding sinuses usually maxilla - due to fractures
Muscles are tethered so eye does not move
How is a blow out fracture diagnosed?
CT scan - teardrop sign
What does orbital fat hypertrophy lead to?
Leads to staring appearance - proptosis
Can be due to thyroid diseases
Can also cause scleral show
What can infection spread from emissary veins to cavernous sinus cause?
Can lead to cavernous sinus thrombosis as travelled from danger area of face
CN4,5,6 affected and causes swelling
Blindness can be caused due to lack of blood supply
What are the symptoms of CN VI palsy?
LR affected as abducent nerve
Eye can adduct but cant abduct
What are the symptoms of CN III palsy?
Eyelid drooping and all muscles affected except SO and LR
Pupillary reflex is tested - large and unreactive
Ptosis
What are the symptoms of CN IV palsy?
SO affected as trochlear nerve
Eye shoots up as result
As adducting the IR is over reacting
SO muscle is paralysed
What can blunt trauma to the eye cause?
Peripheral retina to tear
Vitreous gel gets liquefied
Liquid vitreous pushes through retinal tear which detaches it
What is coloboma?
Congenital malformation of eye causing defects in iris, retina and optic disc
What is the conjunctivae?
Thin vascular membrane covering inner surface of eyelids and loops back over sclera
Does not cover the cornea
Describe conjunctivitis
Self limiting bacterial or viral infection of conjunctivae
Red, watering eye with discharge
No loss of vision as long as the infection does not spread to cornea
What is the treatment for conjunctivitis?
Antibiotic eye drops if likely to be bacterial
What might cause drooping eyelid (ptosis)?
CNIII dystrophy or paralysis
What could cause inability to close eyelid?
CN VII facial nerve palsy
Check other facial nerves
Causes extreme drying and conjunctivitis - ulceration of cornea
Describe a stye/ hordeolum
External stye - hordeolum externum
Infection of hair follicle of eyelash
Internal stye - hordeolum internum
Blockage and infection of Meibomian gland
What is the treatment for a stye?
Warm compress, eyelid hygiene and may need surgical incision and curettage
What do corneal pathologies lead to?
Opacification of cornea
Can be treated with keratoplasty
Describe corneal ulcer
Inflammatory pathology - infectious and needs aggressive management to prevent spread and scarring
If non-infectious then can be trauma, degeneration or dystrophy
What are corneal dystrophies?
Non-inflammatory - bilateral, opacifying, mostly genetically determined and can be due to accumulation of substances in cornea
What is the clinical presentation of corneal dystrophies?
First to fourth decade
Most commonly decreased vision
Starts in one layer of cornea and spreads to others
Describe the occurrence of cataracts in population
30% of people over 65 have some opacity
Each year 225000 new cases
330000 cases operated a year
How do cataracts develop?
Older fibres are never shed so compacted in the middle
No blood supply to lens so depends on diffusion for nutrition
Absorbs harmful UV rays to prevent damage to retina but damages lens so gets opacification
What are immature cataracts?
Seen as spoke like opacities and only cause issues in dull light where pupil naturally dilates so opacities stop light into retina
What is a mature cataract?
No light is let into the retina and nearly blind
What could cause a cataract?
Complication of steroid eye drops in anterior part of lens, blunt trauma or childhood - sutural and zonular (opacification in certain zones in utero)
Describe the management for cataracts
Eye drops do not treat
Surgery - small incision so lens capsule opened and cataract lens is removed by emulsification then plastic lens placed (PCIOL)
What is PCIOL?
Posterior Chamber Intra Ocular Lens
Lens implant after cataract surgery
What is the 2nd most commonest cause of blindness?
Glaucoma
What is glaucoma?
Raised intraocular pressure
Most common form - primary open angle glaucoma
Can be asymptomatic for long period
What are the consequences of raised IOP?
Pressure on nerve fibres on surface of retina so they die out and cause visual field defects
On ophthalmoscopy - optic disc is unhealthy, pale and cupped
Ultimately gets blindness
What are the triad signs of glaucoma?
Raised IOP
Visual field defects
Optic disc changes on ophthalmoscopy
Describe the management of primary open angle glaucoma
Eye drops to decrease IOP - prostaglandins, beta blockers, carbonic anhydrase inhibitors
Laser trabeculoplasty
Trabeculectomy surgery
Describe the presentation of angle closure glaucoma
Sudden onset, painful, vision blurred, headaches, red eye, cornea often opaque, AC shallow, angle closed, pupil mid-dilated and IOP severely raised
What are the mechanisms causing angle close?
Functional block in small eye - large lens
Mid-dilated pupil - periphery of iris crowds angle and outflow obstructed
Iris sticks of pupillary border prevents reaching of AC - iris balloons anteriorly and obstructs angle
How can IOP be decreased for management of acute episode of angle closure glaucoma?
IV infusion with or without oral therapy - carbonic anhydrase inhibitors
Analgesics and antiemetics
Constrictor eye drops - pilocarpine
Beta blockers - timolol is contraindicated
Steroid eye drops - dexamethasone
What surgery is given for management of acute episode of angle closure glaucoma?
Iridotomy laser of both eyes to bypass the blockage
In open angle glaucoma what increases IOP?
Trabecular meshwork is blocked so leads to gradual and painless build up of IOP
This is POAG
What are the types of uveitis?
Anterior - iris or with/without ciliary body is inflamed
Intermediate - ciliary body inflamed
Posterior - choroid inflamed
In angle closed glaucoma what increases IOP?
Event of predisposed eye leads to peripheral iris blocking the angle therefor AH can’t drain
Sudden increase in IOP so sudden red and severe pain
Usually emergency
What are the causes of uveitis?
Isolated illness, non-infectious autoimmune cause, infectious and associated with systemic diseases (ankylosing spondylosis)
Describe pathophysiology of uveitis
Inflamed anterior uvea (iris) leaks plasma and white blood cells into AH
Hazy anterior chamber and cells deposited at back of cornea
Red, painful and vision loss
Cell in AC may settle inferiorly - hypopyon
