Common Conditions Flashcards
What are cataracts?
Opacification of the lens of the eye.
How does someone with cataracts present?
Gradual painless loss of visual acuity i.e. vision clouds over
What is the cause of cataracts?
Age is the main cause.
Congenital
Secondary to medication
UV light exposure (sunny climates or high altitudes)
When should surgery be considered for someone with cataracts?
Visual acuity of <6/18 in one or both eyes
What are the risk factors for cataracts?
Trauma smoking alcohol diabetes Metabolic diseases Outdoor occupation Female
Other than painless gradual loss of vision, what symptoms do pts with cataracts get?
Glare e.g. when driving at night
Change in refractive error (need to change glasses often)
Difficulty reading/recognising faces/driving
O/E of a patient with suspected cataracts, what are you looking for?
- Reduced visual acuity
- Slit lamp or ophthalmoscope -> black cataract seen against red reflex
- Reduced red reflex
- Normal pupillary reactions
What can we do to assist diagnosis of cataracts being made in examination?
Dilate the pupils
How are cataracts treated?
Surgery
What is the most common method of cataract treatment?
Phaecoemulsification
What is phaecoemulsification?
Lens is dissolved with ultrasound then replaced with a plastic or silicone lens.
Done under local anaesthetic generally, but can be done under GA if needed.
When might cataract surgery be done under GA?
Pt with dementia
Child
Learning difficulties
Can you do both cataracts at the same time?
No - should just do one in one day, as a patch needs to sit on the eye for 24 hours afterwards.
What post-op care should we give the pt after cataract surgery?
Full recovery/maximum vision benefit usually takes 2-3 months
Avoid bending and strenuous exercise for several weeks post-op.
May have steroids, abx, or dilating drops prescribed during recovery.
When is cataract surgery contraindicated?
Diabetic retinopathy
Intraoccular inflammation
What are the possible complications of cataract surgery?
- Bleeding
- Vitreous loss
- Endophthalmitis
- Opacification of capsule
- Glaucoma
What medications can cause cataracts?
Systemic corticosteroids are the most common iatrogenic cause.
What is the lens made of?
Collagen (mainly Type IV)
How are lens fibres arranged? How does this connect to cataracts?
Lengthwise from anterior to posterior poles, stacked in concentric layers. Crstallin fibres link them. Disruption of these fibres leads to protein aggregation -> cataracts.
What are the main subdivisions of cataracts, and how are they classified?
- Nuclear sclerosis - cataract formed by new layers of fibre -> lens compression.
- Cortical - new fibres added to outside of lens.
- Posterior subcapsular - opacity in central posterior cortex.
Tell me about paediatric cataracts.
May be:
- Congenital - hereditary, metabolic, or infection (TORCH)
- Developmental - genetic or metabolic
- Acquired - metabolic (DM), trauma, post-radiotherapy
What is the most comon cause of paediatric cataracts?
Congenital -> IntrauterineInfection - most common is rubella
What is amblyopia?
A conditions where there is a reduction in visual acuity due to a problem focussing in early childhood as the brain is not stimulated to develop correctly.
What is the most common cause of amblyopia?
Strabismus (“lazy eye”)
How is amblyopia diagnosed?
Snellen chart and visual acuity testing - due to how the test is performed, this isn’t possible until they are at least 4-5 years old.
How should strabismus causing amblyopia be managed?
-Patches or eye drops - obscure the vision of the good eye and force the brain to porcess the image from the other eye.
How do drops work to treat strabismus?
Dilates pupil usually using atropine. This blurs the vision so the brain ignores the image coming from it.
How does an eye patch work to treat strabismus?
Obscure they eye so there is only input coming from the affected eye.
How long should the drops/patch be used to treat strabismus?
For 4-6 hours a day - no more because otherwise the other eye might not develop so well.
Review after 3 months, continue Rx until no more improvement is seen.
Why do all cases of strabismus need to be referred to a specialist?
To rule out a significant cause such as retinoblastoma or congenital cataracts.
How can a refractive error causing amblyopia be treated?
Correct the error with glasses.
When does the neuro-retina stop developing in response to visual stimuli?
Age 7-8
How common is amblyopia?
Prevalence of 1-3% - it is the most frequently treated disorder in paediatric ophthalmology.
How does amblyopia present?
Unilateral decrease in visual acuity, with a squint or reduced visual acuity following struggling at school.
When might amblyopia be picked up?
Preschool vision screening, or the NIPE/6-8 week check depending on the cause.
What factors make treatment for amblyopia more likely to be successful?
- Young age at start of therapy
- Strabismic amblyopia (easiest to treat)
- Better initial visual acuity
What roles do tears play in the eyes?
Hydration
Immunological
Nourishing
Lubricating
How common is dry eye syndrome?
Very - affects 15-33% of people over 65.
50% more common in women than men.
What causes dry eye syndrome?
- Insufficient tear production
- Excess tear loss
- Abnormalities of eyelids or blinking
- Changes in tear film composition
What are the causes of hyposecretive/tear deficient dry eyes?
- Sjogren’s syndrome
- Lacrimal insufficiency (age related/congenital)
- Lacrimal obstruction
- Reflex hyposecretion
- Medication
What are the evaporative causes of dry eyes?
Mebomian gland dysfunction Blinking disorders Lagophthalmos Contact lens wearing Ocular surface disease
What are the most common causes of dry eyes in GP?
Blepharitis Allergic conjunctivitis Adverse effect of drugs Low humidity Low blink rate (prolonged computer use) Wide lid aperture
How is a diagnosis of dry eye syndrome made?
From hx:
- Gritty irritation
- Foreign body sensation
- Aggravation by air conditioning, prolonged reading, computer work, dry air etc.
- Usually worse towards the end of the day
How do dry eyes look on examination?
-Usually normal
-May have mild conjunctival redness
If long term, looks for complications:
-Conjunctivitis
-Corneal ulcer
What red flags might you find with dry eyes syndrome?
- Moderate to severe eye pain
- Any visual loss
- Photophobia
- Marked redness in one eye
- Diplopia
- Signs of systemic poor health
What are the treatment aims for dry eyes?
- Ease discomfort
- Protect and preserve cornea
- Treat underlying conditions
How should dry eye syndrome be managed?
- Good lid hygiene
- Reduce aggravations inc. medications and smoking
- Treat underlying disease e.g. allergy
- Tear substitutes
What tear substitutes can we use?
Drops
Gels
Ointments
What are the complications of dry eyes?
Conjunctivitis Keratitis Corneal ulcer Infection Corneal perforation (rare)
What is endophthalmitis?
Severe inflammation of anterior and/or posterior chambers of the eye.
May be sterile, bacterial, or fungal.
Define glaucoma.
Gradual death of optic nerve, often associated with high intraocular pressure.
What is glaucoma often due to?
Imbalance of aqueous humour production and drainage.
Tell me about the aqueous pathway?
Aqueous humour is produced by the ciliary body.
The fluid fills the anterior and posterior chambers, and drains out of the eye via the irido-corneal angle in the anteroir chamber, through the trabecular meshwork.
What do we mean by closed and open angle glaucoma?
It refers to the iridocorneal angle = angle between the iris and cornea.
What happens in open angle glaucoma?
The angle is not affected but the trabecular meshwork has a defect which means aqueous humour outflow slows down.
What happens in closed angle glaucoma?
It is usally acute, the iridocorneal angle narrows and obstructs aqueous humour outflow.
What kind of glaucoma is most common?
Open angle
How does open angle glaucoma usually present?
Slow onset deterioration of peripheral vision.
Onset usually over 40, and FHx usually strong.
What are the risk factors for developing glaucoma?
FHx Age over 40 African American Thin corneas Large vertical nerve cupping High eye pressure Long term steroid use
How does prolonged high occular pressure lead to optic nerve atrophy?
Stretching and vascular compromise of optic nerve, and proposed alteration of glutamate transmitter pathways.
What is epiphora?
Watering eyes
What does the tear film do?
Lubricates the cornea
Nourishes cornea
Immunological protection of cornea
What can cause overproduction of tears?
- Lid/lash malposition
- Lid margin disease
- Tear film deficiency
- Corneal foreign body
- Conjunctivitis
- Inflammatory disease
What can cause watery eyes by stenosis/obstruction of nasolacrimal duct?
- Congenital duct obstruction
- Mass
- Lacrimal pump failure
- Nasal obstruction
- Previous trauma/surgery
What kind of endophthalmitis is a medical emergency?
Acute bacterial endophthalmitis
Why is endophthalmitis more common after trauma or surgery?
The blood-ocular barrier usually prevents infection but this is breached.
How common is endophthalmitis?
Rare
What surgical factors increase risk of endophthalitis?
- Previous infection
- Poor surgical technique
- Contaminated intraocular lens
How does endophthalmitis present?
Acute eye pain and decreased vision.
The eyelid may be swollen.
What might be seen on examination of an eye with endophthalmitis?
- Lid oedema
- Corneal oedema
- Conjunctival injection and chemosis
- Decreased visual acuity
- Severe inflammation of anterior chamber and vitreous on slit-lamp examination.
How should endophthalmitis be managed?
- Acute admission to hospital.
- Direct injection of abx into vitreous for bacterial infection
What are the complications of endophthalmitis?
Decrease or loss of vision.
Chronic pain can occasionally occur.
What is proptosis also known as?
Exophthalmos
What is proptosis?
Protrusion of one or both eyes.
What is the most common cause of exophthalmos in adults?
Thyroid eye disease - causes unilateral and bilateral exophthalmos.
What is the most common cause of exophthalmos in children?
Orbital cellulitis if unilateral.
Neuroblastoma or leukaemia if bilateral.
Why does exophthalmos/proptosis occur?
There is limited space in the orbit so any swelling causes the globe to be pushed forwards.
By what mechanisms can exophthalmos/proptosis occur?
- Foreign matter forced into the orbit
- Interference of venous drainage of orbit
- Inflammation within orbit
- New growth within orbit
What can cause pseudo-proptosis?
- Facial asymmetry
- Unilateral globe enlargement
- Lid retraction
- Enophthalmos in other eye
What is pupil size determined by?
The interaction of the parasympathetic and sympathetic nervous system via constriction and dilation of the iris.
What muscle controls dilation of the pupil?
Smooth muscle cells of radial muscle of pupillary sphincter.
What muscle controls constriction of the pupil?
Circular muscle of pupillary sphincter contracts.
What are the pathways that control the pupillary reflex?
An afferent limb from each eye, and 2 efferents limbs returning to the eyes.
What structures make up the afferent limbs of the pupillary constriction pathway?
The retina, optic nerve, and pretectal nucelus.
What structures make up the efferent limbs of the pupillary constriction pathway?
From the pretectal nucleus, the impulse travels to the Edinger-Westphal nucleus which is also situated in the midbrain. The E-W nucelus has 2 motor outputs, one to the pupil on the ipsilateral side, and one to the pupil on the contralateral side. These preganglionic fibres exit the nucleus with the oculomotor nerve and travel via the cavernous sinus through the superior orbital fissure to innervate the pupillary spincter.
What should we look for on general examination of the pupils?
Shape and size of pupils in ambient bright light.
What size is a normal pupil?
Ranges from 1-8mm
When pupillary function is normal, what do the pupils do?
They are equally sized and equally reactive to light.
After testing the red reflex, what tests on the pupil should be performed?
Light reflex - direct and consensual. Swinging flashlight test for relative afferent pupillary defect. Near reflex test (accommodation).
What should happen in a normal eye in the direct light reflex test?
When light is shone into one eye, that pupil constricts briskly.
What should happen in a normal eye in the consensual light reflex test?
When light is shone into one eye, the contralateral pupil constricts briskly and equally to other pupil.
What does the swinging flashlight test look for?
A relative afferent pupillary defect = an asymmetrical abnormality of afferent pathways. The pupils should hold their constriction as the light is swung between eyes.
What does a positive RAPD look like on swinging flashlight test?
Both pupils appear to dilate when light is shone into abnormal eye as the degree of constriction is less than when the light is shone into the normal eye.
If a pt with glaucoma has a RAPD, what might that indicate?
A higher degree of optic nerve damage in one eye than the other.
Other than pupillary constriction, what aspects of eye function are tested by the accomodation relfex?
Increased lens thickness and convergence of the eyes.
What is the fancy word for unequal pupils?
Anisocoria
Can unequal pupils be normal?
Yes - about 20% of the population have normal unequal pupils.
How can you tell which pupil is the abnormal one when the pupils are unequal?
Compare them in light and dark rooms, perform light reflex tests. The problem may be one of dilation of of constriction.
What does a unilateral large pupil look like?
An abnormally dilated pupil in a well lit room.
What can cause a unilateral dilated pupil?
Traumatic iris damage, third nerve palsy, pharmacological dilation.
What does a unilateral small pupil look like?
The pupil is abnormally small in low light.
What can cause a unilateral constricted pupil?
Horner’s syndrome, Uveitis, physiological, pharmacological constriction, and Argyll Robertson pupil.
What are the common causes of RAPD?
Unilateral optic neuropathies e.g. giant cell arteritis. Optic neuritis, seveer glaucoma, traumatic optic neuropathy, optic nerve tumour, ischaemic retinal disease
What does a non-reactive pupil look like?
Fixed dilated pupil.
What might cause unilateral non-reactive pupil?
Trauma, intracranial pathology, diffuse brain injury, thrid nerve palsy, pharmacological blockade, posterior communicating artery aneurysm, ocular prosthesis.
What might cause biilateral non-reactive pupil?
Extensive intracranial pathology, diffuse brain injury, brainstem herniation, brain death, pharmacological blockade.
How does the pupil appear if it is involved in an oculomotor nerve palsy?
Fixed and dilated (or minimally reactive).
Why does CN III palsy without pupil involvement not need immediate attention?
It is usually ischaemic and slower in progression, where as if the pupil is involved there is usually a more urgent and acute cause.
How does a CN III palsy appear?
Down and out appearance of eye, ptosis and pupillary dilation.
How does a CN III palsy present?
Pt experience double vision
Why does ptosis occur in third nerve palsy?
The third nerve provides innervation to levator palpebrae superioris which does most of the work keeping the eyelid open.
What is Horner’s syndrome?
Triad of miosis, anhydrosis and partial ptosis, sometime accompanied by enophthalmos caused by compression of the sympathetic trunk, for example by an apical lung tumour.
What is an Argyll Robertson pupil?
A consequence of long term untreated syphilis characterised by small pupil that reacts very poorly if at all to light, but briskly to accommodation. Pupils are irregular in shape and difficult to dilate.
What might cause an abnormal shaped pupil?
Congenital defect, iridocyclitis, iris trauma, Argyll Robertson pupil, acute angle closure glaucoma.
What congenital abnormalities of the pupil are there?
Aniridia, Coloboma (partial iris defect), and Leukocoria (white pupil).
What topical drugs can dilate the pupils?
Sympathomimetics (phenylephrine, adrenaline) and antimuscarinics (atropine, cyclopentolate)
What topical drugs can constrict the pupils?
Muscarinic agonists e.g. pilocarpine
What systemic drugs can cause pupil dilation?
Sympathomimetics (adrenaline), antimuscarinics (atropine), tricyclic antidepressants, amfetamines, and ecstasy.
What systemic drugs can cause pupil constriction?
Opiates e.g. morphine and organophosphates
What is ocular hypertension?
Intraoccular pressure abover 21 mmHg on 2+ occasions. It is a major risk factor for glaucoma.
What is the main method used to treat glaucoma?
Use of eye drops to reduced intraoccular pressure
What is the current first line eyedrop used to treat glaucoma?
Latanoprost (prostaglandin analogue)
How does latanoprost work to manage glaucoma?
Increases outflow of aqueous humor
Why are many cases of glaucoma missed for so long?
The visual loss is peripheral and the field of vision is covered by the other eye, so visual loss isn’t noticed until it is severe
In management of chronic glaucoma, how are medications initiated?
One at a time
Which patients should not be given prostaglandin analogues to treat glaucoma?
Pregnant or breast-feeding women
Pts with acute uveitis
What are the common side effects of prostaglandin analogues used to managed glaucoma?
- Brown pigmentation of eye
- Lengthening of eyelashes
Aside from prostaglandin analogues, what drug classes can be used to treat glaucoma?
- Beta blockers
- Carbonic anhydrae inhibitors
- Sympathomimetics
- Miotics
- Osmotic diuretics
What is the classic history associated with acute angle-closure glaucoma?
- Severe pain in and around eye
- Blurred vision
- Haloes around lights
- Systemic malaise
- Recent iatrogenic pupil dilation
