Ophthalmology Flashcards
OPEN ANGLE GLAUCOMA
What is glaucoma in general?
- Optic neuropathies associated with raised intraocular pressure (IOP)
OPEN ANGLE GLAUCOMA
What is the pathophysiology of primary open angle glaucoma?
- Gradual increased resistance to aqueous humour outflow through the trabecular meshwork leading to increased IOP
- The iris is CLEAR of the meshwork
OPEN ANGLE GLAUCOMA
What are some risk factors for primary open angle glaucoma?
- Increasing age + FHx
- Black ethnic origin
- Myopia
- HTN + DM
OPEN ANGLE GLAUCOMA
What is the clinical presentation?
- Insidious onset + may be Dx via routine screening at optometrist
- Peripheral vision loss = tunnel vision
- Halos around lights (esp. at night)
- Decreased visual acuity
OPEN ANGLE GLAUCOMA
How is primary open angle glaucoma investigated?
What is gold standard?
- Visual field assessment for peripheral vision loss
- Fundoscopy
- Measuring IOP (non-contact tonometry vs. GOLD STANDARD Goldmann applanation tonometry)
OPEN ANGLE GLAUCOMA
What might fundoscopy reveal in primary open angle glaucoma?
- Optic disc cupping = cup:disc >0.7 (0.4–0.7) as IOP makes optic cup widen + deepen
- Optic disc pallor = optic atrophy
- Bayonetting of vessels = sharp kink as pass over edge of cup
OPEN ANGLE GLAUCOMA
What is the difference between the two methods of measuring IOP?
What is normal IOP and when is it treated?
- Non-contact = screening, estimates IOP by shooting air at cornea
- Goldmann applanation = device on slit lamp directly applies various pressures to cornea
- Normal 10–21mmHg, treat when ≥24mmHg
OPEN ANGLE GLAUCOMA
What is the first line management of primary open angle glaucoma?
What is the mechanism of action?
What are some side effects?
- Prostaglandin analogue eye drops = latanoprost
- Increases uveoscleral outflow
- Eyelash growth + brown iris pigmentation
OPEN ANGLE GLAUCOMA
In terms of second line management of primary open angle glaucoma, how can the drugs be categoried?
- Drugs that reduce aqueous humour production = beta-blockers (timolol) and carbonic anhydrase inhibitors (dorzolamide)
- Drugs that increase uveoscleral outflow = muscarinic receptor agonist/miotic (pilocarpine)
- Drugs that do both = sympathomimetics/alpha-2-agonists (brimonidine)
OPEN ANGLE GLAUCOMA
What conditions would you avoid timolol in?
When would you avoid using brimonidine and what is an adverse effect?
- Asthma + heart block
- Avoid if MAOI/TCA, can cause ocular hyperaemia
OPEN ANGLE GLAUCOMA
What is the mechanism of action of pilocarpine?
What is are some side effects?
- Rapid miosis + contraction of ciliary muscles open trabecular meshwork so increased aqueous humour outflow
- Miosis, headache + blurred vision
OPEN ANGLE GLAUCOMA
If medical management fails in primary open angle glaucoma, what option may be trialled?
- Trabeculectomy = bleb creates new channel for aqueous humour to drain from anterior chamber
ACUTE ANGLE CLOSURE GLAUCOMA
What is the pathophysiology of acute angle closure glaucoma?
- Iris bulges forward + seals off the trabecular meshwork from the anterior chamber preventing drainage of aqueous humour = acute raised IOP
ACUTE ANGLE CLOSURE GLAUCOMA
What are some risk factors of acute angle closure glaucoma?
What medications can precipitate it?
- Hypermetropia, female, Eastern Asian, FHx, cataracts
- Adrenergics (noradrenaline), anticholinergics = both cause mydriasis
ACUTE ANGLE CLOSURE GLAUCOMA
What symptoms may a patient experience in acute angle closure glaucoma?
- Acute, severely painful red eye
- Blurred vision
- Halos around lights
- Headache
- N+V
ACUTE ANGLE CLOSURE GLAUCOMA
What are some signs of acute angle closure glaucoma on examination?
- Dull/hazy cornea due to corneal oedema
- Semi-dilated non-reacting pupil
- Firm eyeball on palpation
- Decreased visual acuity
ACUTE ANGLE CLOSURE GLAUCOMA
How do you manage someone with acute angle closure glaucoma initially?
- EMERGENCY = same-day ophthalmologist assessment
- Combination of eye drops = pilocarpine, timolol, brimonidine
- IV acetazolamide
ACUTE ANGLE CLOSURE GLAUCOMA
What is the definitive management of acute angle closure glaucoma?
- Laser peripheral iridotomy = hole in peripheral iris allows aqueous humour to flow posterior > anterior chamber which relieves pressure pushing iris against cornea
AGE-RELATED MACULAR DEGENERATION
What are the two types of age-related macular degeneration (AMD)?
What is the epidemiology?
- Dry (90%) and wet (10%)
- Most common cause of blindness in the UK
AGE-RELATED MACULAR DEGENERATION
What is the pathophysiology of dry AMD?
- Drusen in Dry
- Caused by atrophy of the retinal pigment epithelium + retinal photoreceptor degeneration > protein/lipid deposits (drusen)
AGE-RELATED MACULAR DEGENERATION
What is the pathophysiology of wet AMD?
- Choroidal neovascularisation into retina where leakage of serous fluid + blood can lead to rapid loss of vision
AGE-RELATED MACULAR DEGENERATION
What is the biggest risk factor of AMD?
What are some other risk factors?
- Advancing age
- Smoking, FHx, CVD risk factors
AGE-RELATED MACULAR DEGENERATION
What is the clinical presentation of AMD?
How may this differ in wet AMD?
- Gradual worsening CENTRAL visual loss = central scotoma
- Reduced visual acuity, esp. low lighting + near field objects
- Fluctuations in visual disturbance which vary day-to-day
- Crooked/wavy appearance of straight lines
- Wet = ACUTE vision loss
AGE-RELATED MACULAR DEGENERATION
What are some tests you would do when examining someone with suspected AMD?
- Snellen chart = reduced visual acuity
- Amsler grid test = assess distortion of straight lines
- Fundoscopy