Glaucoma/Cataracts/Squint/Refractive errors/Trauma Flashcards
What is glaucoma
Chronic diseases characterised by progressive optic neuropathy
What are the types of glaucoma
Closed angle
Open angle
Rubeotic glaucoma
What is open angle glaucoma
The trabecular meshwork is open but aqueous humour is not drained properly due to increased resistance
What is closed angle glaucoma
The trabecular meshwork is blocked hence aqueous humour cannot be drained
What is rubeotic glaucoma
New vessel formation in diabetic eye disease causing obstruction of the trabecular meshwork
Risk factors of open angle glaucoma
Increasing age
Raised Intraocular pressure
Genetics
Afro-Carribean descent
Myopia
Hypertension
Diabetes
Steroids use
Risk factors of closed angle glaucoma
Increasing age
Asian ethnicity
Hypermetropia - long sightedness
Which risk factor for open angled glaucoma is a key modifiable risk factor
Raised intraocular pressure
Difference between open and closed angle glaucoma
OAG is more chronic and gradual whereas CAG is more acute
OAG trabecular meshwork is patent whereas CAG it is not
OAG does not cause pain whereas CAG causes severe pain
Symptoms of open angle glaucoma
Usually asymptomatic and only detected during eye checks because it occurs gradually
Symptoms of closed angle glaucoma
Acute red eye
Painful sudden visual loss
Semi-dilated pupil
Symptoms worse with pupil dilation
Headache
Nausea
Vomiting
Investigations for open angle glaucoma
Assess visual field
Fundoscopy
Slit lamp examination
Applanation tonometry
central corneal thickness measurement
Why is slit lamp examination used to examine for open angle glaucoma
to assess the optic nerve
What is applanation tonometry used for
To measure the intraocular pressure
What may fundoscopy see in open angle glaucoma
Optic disc cupping
Pale optic disc
Bayonetting of vessels
What is bayoneting of vessels
When vessels have breaks as they disappear into the deep cup then re-appear at the base
What causes enlarging of optic cup
Due to loss of optic nerve fibres
Management of open angled glaucoma
- Prostaglandin analogue eye drop
- Beta blockers
- carbonic anhydrase inhibitors
- sympathomimetic eyedrops - Surgery
Example of prostaglandin analogue eye drop
latanoprost
Function of prostaglandin analogue eye drop
Increase uveoscleral outflow (drainage of aqueous humour through the uvea and out of the eye instead of through trabecular meshwork)
Side effects of prostaglandin analogue eye drop
Brown pigmentation of iris
Increased eyelash length
Example of beta blockers used for open angle glaucoma
timolol
Betaxolol
Function of beta blockers in open angle glaucoma
To reduce aqueous humour production
Contraindications of beta blockers for open angle glaucoma
Asthamtics
Patients with heart block
Example of sympathomimetics for open angled glaucoma
Brimonidine - alpha 2 adrenoceptor agonist
Function of brimonidine (sympathomimetics) for open angled glaucoma
Reduce aqueous humour production
increase outflow
Contraindications of sympathomimetics for open angled glaucoma
Patients taking tricyclic antidepressants / other antidepressants such as MAOI
Side effect of sympathomimetics
Hyperaemia
Example of carbonic anhydrase inhibitors used for open angle glaucoma
Dorzolamide
Function of carbonic anhydrase inhibitors used for open angle glaucoma
Reduce aqueous humour production
management of closed angle glaucoma
Urgent referral
Topical parasympathomimetic / beta blockers / alpha- 2 agonists
IV acetazolamide
Laser surgery
Example of parasympathomimeticc for closed angle glaucoma
Pilocarpine
Example of alpha 2 agonist for closed angle glaucoma
Apraclonidine
Function of pilocarpine for closed angle glaucoma
Causes contraction of ciliary muscles to open the trabecular meshwork
What are cataracts
When the lens of the eye gradually opacifies
Cataract is the most common cause of
Curable blindness
Risk factors of cataracts
Women
Increasing age
Causes of cataracts
Normal aging process
Smoking
Diabetes
Steroids
UVB radiation damage
Hypocalcaemia
Symptoms of cataracts
Gradual visual loss
Faded colour vision
Glare - lights appear brighter than usual
Halos around light
Clinical sign of cataract
Loss of red reflex
How does cataract cause defect in red reflex
because the cloudiness of lens makes it difficult for light to reach the retina
Management of cataracts
Surgery to remove the lens and replace with new artificial one
Complications of cataract surgery
Posterior capsule opacification
Retinal detachment
Posterior capsule rupture
Endopthalmitis
What is posterior capsule opacification
Opacification of the lens capsule that surrounds the new implanted lens
What is endopthalmitis
Inflammation of aqueous +/- vitreous humour
What does emmetropia mean
No refractive error, light focused on retina
What does ametrophia mean
Light focused in front or behind of retina
What does anisometrophia mean
Significant difference between right and left ametropia
What causes myopia
Increased axial length of eye
Light focusd in front of retina
management of myopia
Glasses with concave lenses
Myopia can lead to
Open angle glaucoma
What causes hyperopia
Decrease in axial length of eye
Light focused behind the retina
Management of hyperopia
Glasses with convex lenses
Hyperopia can lead to
Closed angle glaucoma
What is strabismus (squint)
when the eyes do not properly align with each other when focusing to look at an object
When does squint usually present
During childhood
Risk factors of squint
Premature birth
Cerebral palsy
Family history of squint
Types of squint
Concomitant
Paralytic
What is concomitant squint
Squint due to imbalance in extra ocular muscles
What is paralytic squint
Squint du to paralysis of extra ocular muscles
Causes of squint
Idiopathic
Congenital
Cranial nerve palsies
Intracranial infection
Myopathy - myasthenia gravis
Symptoms of squint
- Misalignment of the eyes
- Reduced visual acuity
- Diplopia
- Asthenopia (eye strain, fatigue)
If uncorrected, what can squint lead to
Amblyopia - when the brain fails to process inputs from one eye and over time favours the other eye
Investigations for squint
Corneal light reflection test - detect squint
Cover test - identify the nature of squint
Describe the corneal light reflection test
Hold a light source 30cm from the child’s face
See if the light reflects symmetrically on the pupils
Describe the cover test
ask the child to focus on an object
cover one eye
observe movement of uncovered eye
Describe the results of cover test
Outward movement of eye -> esotropia
Inward movement of eye -> exotropia
Downward movement of eye -> hypertrophic
Upward movement of eye -> hypotropia
Management of squint
Referral to secondary care
Cover the unaffected eye using an eye patch to prevent development of amblyopia
What is a blowout fracture
When there is a fracture of one of the orbital walls but the orbital rim remains intact
Which orbital wall is most likely to undergo a blowout fracture
Inferior orbital wall
Why do blow out fractures occur
Because the bone forming the orbital rim is strong but the orbital plates are thinner hence the force can transfer to the thinner orbital plates and cause fracture there
What can happen in a blow out fracture
Orbital fat can prolapse into maxillary sinus
Can trap infraorbital nerves
Can trap inferior rectus muscle
What occurs if infraorbital nerves are trapped in a trapdoor fracture
Parasethesia of the face
What occurs if inferior rectus muscle is trapped in a trapdoor fracture
Unable to look down -> diplopia (since the other side is not affected)
What can cause subconjunctival haemorrhage
After strenuous activities - heavy coughing / weight lifting / straining when constipiated
Trauma
What is hyphema
Blood in the anterior chamber of the eye
What can hyphema lead to
Raised intraocular pressure -> risk of vision loss
Management of hyphema
Urgent referral to ophthalmologist
Strict bed rest
May require admission
Why is strict bed rest required in hyphema
Because movements can redisperse blood that had previously settled
What must be assessed after an ocular trauma
Orbital compartment syndrome
What are the features of orbital compartment syndrome
Eye pain / swelling
Proptosis
Rock hard eyelids
RAPD
Management of orbital compartment syndrome
Urgent surgery to decompress the orbit
Which parts of the eye are down-regulated immune environment
Cornea
Sclera
Retina
Choroid
Vitreous humour
Which part of the eye has a lymphatic drainage? What does this imply
Conjunctiva
This means that immune cells can regulate around here
What does immune privilege mean
Sites that are able to tolerate the introduction of antigens without causing an inflammatory cascade
What is the benefit of immune privilege
It protects these structures in the eye from ocular inflammation
What causes immune privilege
Lack of lymphatic drainage / blood
Lack of APC
Immunosuppressive molecules
Blood tissue barrier
What is an disadvantage of immune privilege of the eye
Because the immune system of the eye is separated from the systemic immune system, the eye has a higher chance of developing autoimmune reaction to an antigen that the systemic immune system has already tolerated (= the eye immune system does not know this antigen is not harmful because the systemic immune system cannot communicate with it)
Example of disadvantage of immune privilege
Sympathetic ophthalmia
What is sympathetic ophthalmia
Bilateral uveitis after trauma to eye due to the exposure of intra-ocular antigens which were previously immune-privileged, causing autoimmune reaction to both eyes
What can be used to see corneal lacerations
Fluorescein stain
