Ophthalmology Flashcards
What is glaucoma?
- Optic nerve damage caused by intraocular pressure rise
- Due to blockage in aqueous humour trying to escape eye
- 2 types-> open + closed angle
What is the anterior chamber?
- Between cornea + iris
- Aqueous humour-> gives nutrients to cornea
What is the posterior chamber?
- Between lens and iris
- Aqueous humour
What is aqueous humour?
- Produced by ciliary body
- Flows around lens and under iris, through trabecular meshwork + into canal of Schlemm
- Found in anterior and posterior chamber
What is the normal intraocular pressure?
- 10-21mmHg
- Resistance to flow through trabecular meshwork into canal of Schlemm
What is the pathophysiology of open angle glaucoma?
- Gradual increase in resistance through trabecular meshwork
- Hard for aqueous humour to flow + exit the eye
- Pressure builds slowly
- Can cause optic cupping-> optic cup in disc centre becomes larger + wider
What are the risk factors for developing open angle glaucoma?
- Age
- FH
- Black
- Myopia (near sighted)
What is the vitreous chamber?
- Filled with vitreous humour
- Behind lens-> most of eye
How does open angle glaucoma present?
- Asymptomatic + found on screening
- Tunnel vision (peripheral)
- Gradual onset
- Pain, headaches, blurred vision, halos around lights at night
How is intraocular pressure measured?
- Non-contact tonometry machine-> puff of air + measure corneal response
- Goldmann applanation tonometry-> contact with cornea + more accurate measurement
How is open angle glaucoma diagnosed?
- Goldmann applantation tonometry
- Fundoscopy-> cupping + nerve health
- Visual field assessment
How is open angle glaucoma managed?
- Treatment started at >24mmHg
- Latanaprost-> prostaglandin analogue eye drops (increase uveoscleral outflow)
- Timolol-> beta-blocker to reduce humour production
- Dorzolamide or brimonidine
- Surgery-> trabeculotomy ie new channel + bleb for drainage
What is latanaprost?
- prostaglandin analogue eye drops (increase uveoscleral outflow)
- used in open angle glaucoma
- can cause eyelid + iris pigmentation
What is the pathophysiology of acute angle-closure glaucoma?
- Iris bulge forward + seal off trabecular meshwork from anterior chamber
- Prevents aqueous humour drainage
- Pressure builds in posterior chamber
- Iris bulges
What are the risk factors for acute angle-closure glaucoma?
- Age
- Female
- Family history
- Chinese + East Asian (rare in black people)
- Shallow anterior chamber
- Medications-> noradrenaline, oxybutynin, amitriptyline
How does acute angle-closure glaucoma present?
- Unwell
- Severe red eye pain
- Blurred vision
- Halos around lights
- Headache
- Nausea + vomiting
What examination findings might be present in acute angle-closure glaucoma?
- Red + teary eye
- Hazy cornea
- Decreased acuity
- Dilated/fixed pupil
- Firm eyeball
How is acute angle-closure glaucoma managed?
- Same day assessment from ophthalmology
- Lie on back without pillow
- Pilocarpine eye drops
- Acetazolamide
- Timolol (beta-blocker)
- Hyperosmotic agents-> glycerol or mannitol
- Laser iridotomy-> laser hole in eye
What are pilocarpine eye drops?
- Act on muscarinic receptors in sphincter muscles of iris-> pupil constriction
- Miotic agent
- Ciliary muscle contraction
- Cause flow of aqueous humour pathway to open
- Used in acute angle-closure glaucoma
What is acetazolamide?
- Carbonic anhydrase inhibitor
- Reduces aqueous humour production
- Used in acute angle-closure glaucoma
What is age-related macular degeneration?
- Degeneration of macula-> part of retina responsible for central + colour vision
- Dry (90%) or wet (10%)
What does the macula consist of?
Central + colour vision…
- Choroid layer-> BV supply
- Bruch’s membrane
- Retinal pigment epithelium
- Photoreceptors
What is drusen?
- Fundoscopy finding in age-related macular degeneration
- Deposits of protein + lipids between Bruch’s membrane + retinal pigment epiethlium
- Larger + greater than normal-> early sign
What is the pathophysiology of wet age-related macular degeneration?
- New vessels grow from choroid layer into retina
- Due to vascular endothelial growth factor (VEGF)
- Leak fluid/blood-> oedema + rapid vision loss
What are the risk factors for age-related macular degeneration?
- Older
- Smoking
- White
- Chinese
- Family history
- CVD
How does wet age-related macular degeneration present?
- Central visual field loss-> over few days then full over a few years
- Reduced acuity
- Crooked/wavy appearance to straight lines
- Often progress to bilateral
How does dry age-related macular degeneration present?
- Gradual central visual field loss
- Reduced acuity
- Crooked/wavy appearance to straight lines
How is age-related macular degeneration investigated?
- Full eye exam
- Slit lamp biomicroscopic fundus exam
- Optical coherence tomography (wet)
- Fluorescein angiography
How is dry age-related macular degeneration managed?
- Ophthalmology referral
- Lifestyle-> smoking, HTN control, vitamin supplements
How is wet age-related macular degeneration managed?
- Ophthalmology referral
- Anti-VEGF meds-> ranibizumab injections
What causes diabetic retinopathy?
- Blood vessels in retina damaged by prolonged exposure to hyperglycaemia
- Progressive degeneration of retina health
What is the pathophysiology of diabetic retinopathy and its features?
- Hyperglycaemia-> retinal small vessel + endothelial damage
- Increased vascular permeability-> leakage from BVs, blot haemorrhages
- Hard exudates-> yellow/white
- Microanurysms-> weakness in walls causes bulges
- Venous bleeding-> veins like beads
- Nerve fibre damage-> cotton wool spots (fluffy white on retina)
- Intraretinal microvascular abnormalities-> dilated capillaries + can act as shunt
- Neovascularisation-> GFs released + cause new BV formation
What are some features of diabetic retinopathy?
- Blot haemorrhages
- Lipid deposits/exudates
- Microaneurysms
- Venous bleeding
- Cotton wool spots
- Neovascularisation
- Intraretinal microvascular abnormalities
What are the two categories of diabetic retinopathy?
- Proliferative
- Non-proliferative
What are the categories + features of non-proliferative diabetic retinopathy?
- Mild-> microaneurysms
- Moderate-> + blot haemorrhages, hard exudates, cotton wool spots, venous bleeding
- Severe-> blot haemorrhages + microaneurysms in 4 quadrants, venous beating in 2 quadrants, IMRA in any quadrant
What are the features of proliferative diabetic retinopathy?
- Neovascularisation
- Vitreous haemorrhage
What is diabetic maculopathy?
Macular oedema + ischaemic maculopathy
What are the complications of diabetic retinopathy?
- Retinal detachment
- Vitreous haemorrhage
- Optic neuropathy
- Cataracts
- Rebeosis iridis-> new BVs on iris
What is the management of diabetic retinopathy?
- Laser photocoagulation
- Anti-VEGF-> ranibizumab
- Vitreoretinal surgery-> severe
What is the pathophysiology of hypertensive retinopathy?
- Damage to small BVs in retina related to systemic HTN
- Develops from chronic or malignant HTN
What are the retinal signs of hypertensive retinopathy?
- Silver/copper wiring-> thick + sclerosed arteriole walls
- AV nipping
- Cotton wool spots-> ischaemia + infarction causes nerve fibre damage
- Hard exudates
- Retinal haemorrhages
- Papilloedema-> ischaemia to optic nerve so swells
What is the Keith-Wagener classification?
For hypertensive retinopathy…
- Stage 1-> mild narrowing of arterioles
- Stage 2-> focal constriction of BVs + AV nicking
- Stage 3-> cotton-wool patches, exudates, haemorrhages
- Stage 4-> papilloedema
How is hypertensive retinopathy managed?
Control HTN + risk factors-> smoking, lipids etc
What is anterior uveitis?
- Inflammation in anterior part of uvea (iris + ciliary body + choroid)
- Inflammation + immune cell infiltration of anterior chamber-> floaters
What is the choroid?
Layer between retina + sclera all the way around the eye
What can cause anterior uveitis?
- Autoimmune
- Infection
- Trauma
- Ischaemia
- Malignancy
What is associated with anterior uveitis?
- HLAB27 conditions-> IBD, reactive arthritis, ankylosing spondylitis
- Chronic-> sarcoidosis, syphilis, Lyme’s, TB, herpes
What is chronic anterior uveitis and how does it present?
- More granulomatous-> increased macrophage infiltration of anterior chamber
- Less severe than acute
- Over 3+ months
How does anterior uveitis present?
- Unilateral, spontaneous + without trauma
- May get flare up if have chronic condition
- Pain-> dull, on movement
- Red eye + ciliary flush (red ring)
- Vision-> reduced acuity, floaters, flashes, photophobia
- Pupil-> miosis + abnormal shape as adhesions pull
- Excess lacrimation
- Hypopyon-> yellow fluid (WBC) in lower iris
How is anterior uveitis managed?
- Same say ophthalmology
- Steroids
- Immunosuppressants-> DMARDs, TNF-inhibitors
- Laser therapy
- Cyclopentolate or atropine eye drops
How do atropine eye drops work?
- Cycloplegic-mydriatic
- Paralyse ciliary muscle + dilate pupils
- Antimuscarinics
What is episcleritis?
- Benign + self-limiting
- Inflammation of episclera-> outer layer of sclera under conjunct
Who is episcleritis most common in?
- Young
- Middle aged
- Associated with RA + IBD
- Not usually infection
How does episcleritis present?
- Acute onset
- Unilateral
- None to mild pain
- Patch of redness in lateral sclera
- Foreign body sensation
- Dilated episcleral vessels
- Watery eye
- No discharge
How is episcleritis managed?
- Recovers in 1-4 weeks
- No treatment needed usually
- Lubricating eye drops
- Analgesia + cold compression
- Safety netting
- Severe-> systemic NSAIDs, topical steroid eye drops
What are cataracts?
Lens becomes cloudy + opaque over time due to age + risk factors-> reduced acuity
How does the lens of the eye work?
- Focuses light into eye + retina
- Held by suspensory ligaments attached to ciliary body
- Ciliary body relaxes-> increased tension of suspensory ligaments-> lens narrows
- Nourished by surrounding fluid (no blood supply)
What are the risk factors for cataracts?
- Older age
- Smoking
- Alcohol
- Diabetes
- Steroids
- Hypoglycaemia
How does cataracts present?
- Asymmetrical reduction + blurring of vision
- Colour vision change-> brown/yellow
- Starbursts around lights at night
- Loss of red reflex
How does vision loss in cataracts compare to loss in other eye conditions?
- Cataracts-> general reduction in acuity + starbursts
- Glaucoma-> peripheral vision loss + halos round lights
- Macular degeneration-> central vision loss + wavy/crooked appearance to straight lines
How are cataracts managed?
- None if symptoms manageable
- Surgery-> drill + break lens then remove + implant artificial one
What are the complications of cataract surgery?
- Prevent detection of other pathology eg macular degeneration
- Poor visual acuity
- Endophthalmitis-> infection/inflammation of inner eye contents + can cause loss of vision
What causes pupillary constriction?
- Circular muscles in iris
- Stimulated by parasympathetic nervous system-> travels to eye via CNIII
- Involved acetylcholine NT
What causes pupil dilation?
- Dilator muscles from inside to outside of iris
- Stimulated by sympathetic nervous system
- Adrenaline NT
What can cause an abnormal pupil shape?
- Cataract surgery
- Trauma
- Adhesions/scars from infection
- Anterior uveitis
- Acute angle closure glaucoma
- Rubeosis iridis
- Coloboma
- Tadpole pupil-> from migraines
What is mydriasis?
Dilated pupil