OPHTHALMOLOGY PROBLEMS

what does vision require

• light

• eyes

• brain

which nerve allows us to see

CN II - the optic nerve

• ‘nerve of sight’

what does the retina do

converts light energy into electrical impulses that travel down the optic nerve to the brain for processing (ultimately to the occipital cortex)

image showing orbital contents

we can see the iris because of the…

cornea - needs to be clear for the iris to be visible (covers iris + pupil)

(CONJUNCTIVA COVERS THE SCLERA)

label this image

THIS IS AN IMAGE OF THE RETINA

where are cones concentrated

at the macula

where are rods concentrated

around the periphery of the retina

what structure converges at the optic disc

axons converge at the optic disc

what is the relationship between the retina and the optic nerve

the axons in the retina come together to form the optic nerve

visual disturbance VS visual loss

• visual disturbance can be transient

• visual loss is not usually transient

what are causes of visual disturbance

visual disturbance can arise from:

• a pathological process affecting the eye

• a pathological process affecting brain structures involved in visual processing

how can we narrow down the causes of visual disturbance

• how exactly is the vision disturbed?

• other features/ signs/ symptoms the patient is experiencing?

give examples of how vision can be disturbed (5)

• loss of vision

• visual field defect

  • central vision

  • peripheral vision

  • one or both eyes affected

• flashing lights

• floaters

• double vision (diplopia)

what are some other features/ signs/ symptoms of visual disturbance (6)

• pain

• redness

• droopy lid (ptosis)

• pupil size inequalities

• systemic symptoms e.g. headache

• recent surgery

which examples of vision disturbance and other features/ signs/ symptoms of visual disturbance are red flags (6)

• visual field defect

  • central vision

  • peripheral vision

  • one or both eyes affected

• double vision (diplopia)

—

• pain

• redness

• systemic symptoms e.g. headache

• recent surgery

what are ‘eye causes’ of visual disturbance (5)

• cataracts

• macular degeneration

• glaucoma - damage due to raised intraocular pressure

• retinal detachment

• eye infections

what are ‘brain causes’ of visual disturbance (4)

• stroke

  • n.b. amaurosis fugax

• inflammations

• migraine

• raised intracranial pressure

what are ‘systemic causes’ of visual disturbance (4)

• diabetes and diabetic retinopathy

• vessel occlusions and atherosclerosis

• giant cell arteritis

• accelerated hypertension

what are cataracts and what are they caused by

• cataracts are an opacification of the lens

• typically due to ageing

in which demographic do cataracts occur earlier in

in diabetics and following trauma/ steroid use

what do cataracts result in

a gradual loss of vision

why does diabetic retinopathy cause visual disturbance

chronically high blood glucose levels damages the microvasculature in the eye

what are consequences of diabetic retinopathy

in the eye, retinal vessels can:

• become ‘leaky’ » retinal oedema (most significant if macula is affected)

• shut down » retinal ischaemia and new blood vessel growth (neovascularisation)

  • which can then bleed and cause visual loss

worsening diabetic eye disease is associated with…

poor diabetic control

how are diabetics monitored for changes in the eye

the diabetic eye screening service monitors for changes

what are causes of flashes

what are causes of floaters

• flashing lights can be produced by mechanical tugging on the retina

• floaters can occur from vitreous debris

(both flashes and floaters are very common)

give examples of vitreous debris

• embryological remnants

• posterior vitreous detachment (PVD)

• post inflammation e.g. infection

if someone experiences a ‘sudden shower of floaters’, what is the likely cause of this

• likely completed posterior vitreous detachment (PVD)

  • should check for retinal tear

if someone experiences a ‘floaters and flashing lights’, what is the likely cause of this

• likely posterior vitreous detachment (PVD)

  • should check for retinal tear

if someone experiences a ‘flashing lights followed by a curtain of vision loss’, what is the likely cause of this

• suspect retinal detachment

if someone experiences a ‘floaters with darkening of the vision’, what is the likely cause of this

• suspect vitreous haemorrhage

what is the cause of visual field defects

• a lesion in any part of the visual pathway gives you a particular visual field defect

(therefore you can pinpoint a visual field defect to a particular location in the visual pathway)

diagram showing examples of visual field defects

what is the relationship between the location of the lesion in relation to the optic chiasm and which eye(s) are affected

lesions that happen posterior to the optic chiasm will affect both eyes

lesions that happen anterior to the optic chiasm will affect one eye

pie chart showing causes of visual loss

state causes of visual loss

• macular degeneration

  • Age-Related Macular Degeneration (AMD)

• chronic open angle glaucoma

• acute angle closure glaucoma

what are the types of macular degeneration (AMD)

• wet AMD

• dry AMD

outline wet AMD

• new blood vessel growth at the macular area

  • these blood vessels leak fluid

what is the treatment for wet AMD

• intravitreal anti-VEGF injection

  • VEGF = protein that causes abnormal leaky blood vessels to grow beneath retina

outline dry AMD

• deposits called ‘drusen’ are found in the macular region

what is the treatment for dry AMD

there is no treatment for dry AMD

what is chronic open angle glaucoma

a group of conditions that lead to progressive retinal nerve fibre layer thinning and optic disc changes

what is the largest modifiable risk factor for chronic open angle glaucoma

largest modifiable risk factor is intraocular pressure (IOP)

why does chronic open angle glaucoma cause vision loss

• there is decreased outflow at the trabecular meshwork

  • trabecular meshwork is the primary outflow pathway for aqueous humour (eye drainage)

how do medications for chronic open angle glaucoma work

medications can:

• increase alternate outflow

• decrease aqueous production

what is a normal patient history for someone who has acute angle closure glaucoma

• prolonged time spent in dim lighting

• positions

  • laying prone and going from sitting » supine increases IOP

• emotional stress

• pharmacological

why is darkness a trigger for acute angle closure glaucoma

• because darkness causes the pupil to dilate

• this can block drainage of aqueous humour

what are signs of acute angle closure glaucoma

• decreased visual acuity

• IOP 40+

• ciliary injection

• mid-dilated, non-reactive pupil

• synechiae (when the iris sticks to other structures in the eye)

what are the types of management for acute angle closure glaucoma

• medical

• surgical

what are some conditions that can cause a red eye and which respective structure is affected (8)

1. pre-septal cellulitis, orbital cellulitis, blepharitis (eyelids)

2. keratitis, ulcers (cornea)

3. bacterial/ viral/ allergy/ neoplasia (conjunctiva)

4. episcleritis (episclera)

5. scleritis (sclera)

6. uveitis (uveal tract)

7. angle closure (angle)

8. endophthalmitis (vitreous)

outline pre-septal cellulitis

• associated with skin commensal bacteria e.g. S.aureus, S.pyogenes

  • e.g. lid abrasions, insect bites, hordeola (stye), dacryocystitis

what is the Tx for pre-septal cellulitis

oral antibiotics e.g. co-amoxiclav

outline orbital cellulitis

• associated with paranasal sinus infections by S.pneumoniae and Haemophilus

  • e.g. dacryocystitis, tooth infections

• sight and life threatening

what can orbital cellulitis be complicated by

can be complicated by:

• abscesses

• cavernous sinus thrombosis

what is the Tx for orbital cellulitis

• hospital admission

• IV ceftazidime/ metronidazole

• monitor visual acuity (VA), RAPD, colour vision

what are other causes of a red eye

• sub-conjunctival haemorrhage

• conjunctivitis

outline sub-conjunctival haemorrhage (causes and recovery period)

• typically idiopathic

  • can result from Valsalva maneuovre (vomiting, coughing, sneezing, straining)

  • and trauma/ medications/ high BP

• resolves in 1-2 weeks without treatment

if sub-conjunctival haemorrhage is found in children, what should be considered

non-accidental injury (NAI)

what are symptoms of conjunctivitis

• discharge - watery, mucoid, purulent

• chemosis - swelling of conjunctiva

• lymphadenopathy

• sexual history

(can be viral, bacterial, allergy)

what are symptoms of bacterial conjunctivitis (4)

• injection

• purulent discharge

• lashes stuck together in the mornings

• gritty sensation

what is the Tx for bacterial conjuncitivitis

chloramphenicol eye drops/ ointment

what are symptoms of viral conjunctivitis (6)

• injection

• water discharge

• gritty discharge

• one eye is affected first then the other

• may be associated with prior URTI

• lid swelling

what are symptoms of allergic conjuncitivitis (3)

• chemosis

• itching

• mucoid discharge

seasonal, also associated with asthma and eczema

what is the Tx for allergic conjunctivitis

• cool compresses

• cromoglycate eyedrops

• antihistamines

what are symptoms of STI associated conjunctivitis

• gonorrhoea

  • rapidly progressive

  • mucoid discharge

  • corneal perforation

• chlamydia

  • watery discharge

how else can conjunctivitis be contracted

neonatal conjunctivitis (from mother)

what is uveitis

• an inflammatory process within the front of the eye (the uvea)

  • incl. iris, ciliary body, choroid

• vision can be decreased

what are symptoms of uveitis

• pain

• photophobia

what is the Tx for uveitis

• referral to eye doctor

• steroid eyedrops (autoimmune so antibiotics will not be effective)

what other conditions can uveitis be linked to (2)

• Crohn’s disease

• rheumatoid arthritis

referral pathways for ophthalmic problems