Ophthalmology Flashcards
Describe the 3 layers of the eye
Fibrous / outer layer: sclera - tough outer layer, attachment for extraocular muscles, covered by thin transparent conjunctiva (also covers inner eyelids); cornea - avascular and highly innervated, dome that changes shape to focus light on the retina
Vascular layer: choroid - vascular tissue that provides oxygen + nutrients to outer layers of the retina; ciliary body - ciliary muscle (smooth) controls the shape of lens and contributes to the formations of aqueous humour, attached to lens by ciliary processes; iris - circular structure, smooth autonomic muscle control diameter of pupil
Inner / retina: pigmented - single layer of cells, attached to choroid, absorbs light to avoid scattering, whole inner surface of eye; neural - photoreceptors, posterior + lateral; centre of retina = macula, fovea centralis has high concentration of light detecting cells, responsible for high acuity vision; optic disc around optic nerve has no light detecting cells; anteriorly has pigmented but no neural - non-visual retina
Describe presentations of eye cranial nerve palsies
III: down + out (unopposed lateral rectus + superior oblique), ptosis (eyelid drooping), diplopia, if parasympathetic too - mydriasis (dilated pupil) + loss of accommodation
IV: elevated + maybe extortion, worst when looking down + in - reading, walking downstairs; patients adopt compensatory head tilt to opposite side of lesion to minimise diplopia
VI: turned medially, horizontal diplopia when looking towards affected side, patients may turn toward affected side
What is the pathophysiology and risk factors of acute angle closure and open angle glaucoma
Sight threatening emergency (optic nerve damage), rapid rise in intraocular pressure due to obstruction of aqueous humour outflow (pupillary block), increasing pressure pushes iris forward exacerbating the angle closure
Elderly females, hyperopic (farsighted), shallow anterior chamber / thick peripheral iris, FHx, east asian
Meds: adrenergic (noradrenaline), anticholinergics (oxybutynin), tricyclics
Gradual increase in resistance through trabecular meshwork (age related, debris, fibrosis)
Age, FHx, black, myopia (nearsighted). Most common form of reversible blindness
Acute angle closure glaucoma Px, Ix, Mx
Presentation: severe ocular pain, headache, nausea, vomiting, red eye, hazy cornea. Peripheral visual acuity reduced + halos around lights, pupil can be fixed + mid dilated, increased cup-disk ratio
Early diagnosis essential: gonioscopy (special contact lens + slit lamp) to view angle, eye examination, Goldmann tonometry shows raised IOP (>40 mmHg, should be 10-21)
Emergency medical treatment:
Lie patient on back, pilocarpine eye drops (2% blue eyes, 4% brown), topical timolol (BB, alternatively alpha agonist or prostaglandins), oral acetazolamide (or dorzolamide drops), IV mannitol, analgesia + antiemetic
Definitive treatment (chronic): laser peripheral iridotomy, hole in iris to allow flow
(Pilocarpine - cholinergic agonist + miotic agent causes pupil + ciliary muscle contraction (opens channel)
Timolol - unknown but likely reduced production of aqueous
Acetazolamide: carbonic anhydrase inhibitor - reduced production of aqueous humour)
Open angle glaucoma Px, Ix, Mx
Presentation: (asymptomatic if found early), gradual peripheral vision loss, fluctuating pain, headaches, blurred vision, halos around lights
Ix: tonometry (Goldmann GS, non contact most common), gonioscopy + slit lamp, examination
Mx (>24 mmHg): 360 degree laser trabeculoplasty for all patients - laser on trabecular meshwork; latanoprost (prostaglandin, increase uveoscleral outflow) FL medical treatment
Also: timolol, dorzolamide (carbonic anhydrase inhibitor), brimonidine (symp)
If ineffective - trabeculectomy, new channel from anterior chamber
Describe the difference between dry and wet macular degeneration
Wet is 10%, neovascularisation, leakage of serous + blood, risk of rapid vision loss, is curable
Dry: 90%, RPE + photoreceptor atrophy, gradual vision loss, supportive treatment
Age related macular degeneration Px, Ix, Mx
Px: reduction in bilateral central visual acuity (particularly close objects), difficulty in dark adaptation, fluctuation in visual disturbance, photopsia (flashing lights + glare), visual hallucinations, straight lines appear wavy
Ix: slit lamp (exudative or haemorrhagic changes in retina), fundoscopy (drusen), amsler grid (wavy lines), optical coherence tomography (cross sectional view of retina - diagnosis and monitoring)
Mx: early stage: observation + risk factor modification; intermediate: antioxidant vitamin supplementation (zinc, A, C, E), specialist referral;
Mx wet: anti-VEGF (vascular endothelial growth factor) injections into vitreous chamber
Central retinal artery occlusion Px, Ix, MX
Sudden onset (seconds) monocular vision loss, painless, RAPD
Swinging light test (complete / relative afferent papillary defect), fundoscopy (cherry-red spot in centre of macula, white ischaemic retinal areas); causes: carotid doppler, heart auscultation + ECG, ESR + CRP (giant cell arteritis)
Mx: within 6h, urokinase thrombolysis through ophthalmic artery catheterisation, ocular massage (<90m), anterior chamber paracentesis, sublingual isosorbide dinitrate
If giant cell arteritis - IV steroids
Diabetic retinopathy pathophysiology and fundoscopy findings
Hyperglycaemia damages retinal small vessels and endothelial cells; increased vascular permeability (leaking vessels, haemorrhages, hard exudates), microaneurysms, venous beading, damage to nerve vessels (cotton-wool spots), neovascularisation (due to ischaemia) and vitreous haemorrhage
Grading based on fundoscopy findings: non-proliferative (early): everything above other than; proliferative: neovascularisation and vitreous haemorrhage
Diabetic retinopathy Px, Mx, complications
Px: asymptomatic, blurred vision, floaters, dark areas in field, vision loss
Mx: good diabetic control; proliferative: laser photocoagulation, anti-VEGF, vitrectomy; dexamethasone intravitreal implant for macular oedema
Complications; vision loss, retinal detachment, vitreous haemorrhage, optic neuropathy, cataracts
Diabetic maculopathy: oedema + protein on / under macula leading to vision loss
Cataracts pathophysiology, Px, Ix, Mx
Opacification of crystalline lens, progressive decline in visual activity due to loss of light hitting retina, combination of factors - oxidative stress / osmotic imbalance (swelling) / glycation due to age
(Age, smoking, alcohol, diabetes, steroids, hypocalcaemia)
Px: asymmetrical, progressive loss of acuity + blurring, colours become faded / brown, starbursts around lights, change in prescription glasses. Loss of red reflex + opacification of lens
Fundoscopy (normal fundus + optic nerve), slit lamp (visible cataract)
Mx: conservative for mild, once symptoms unmanageable surgery only treatment; breaking apart of lens, removal and replacement with an artificial lens
Conjunctivitis Px, Ix, Mx. Most common cause
Acute onset, typically unilateral (may progress to bi), exposure (contact lens, swimming, contact), discomfort / itching / burning, foreign body sensation. Eyelid swelling + erythema
Viral: serous discharge, recent URTI, preauricular lymph nodes
Bacterial: purulent discharge, eyes stick together (especially morning)
Usually resolves within 2w without treatment
Hygiene (avoid contact, washing with cool boiled water + cotton wool); bacterial: topical chloramphenicol every 3h (fusidic acid in pregnancy). No contact lenses
Viral > bacterial, adenovirus most common
Retinal detachment Px, Ix, Mx
Px: new onset floaters / flashes, sudden onset painless + progressive visual field loss from periphery, if macula is involved will also affect central acuity
Examination, red reflex lost on fundoscopy + retinal folds pale / opaque
Mx: urgent referral, treat tear with laser / cryotherapy, reattach retina with vitrectomy / scleral buckle / pneumatic retinopexy
Anterior uveitis Px, Ix, Mx
Px: painful (dull aching), red, reduced visual acuity, photophobia, excessive lacrimation. Ciliary flush (cornea outwards), miosis (constricted pupil) and abnormal shape, hypopyon (white fluid in anterior chamber due to inflammatory cells)
Ix: slit lamp (anterior chamber cells, flare, keratic precipitates), intraocular pressure and fundoscopy for complications. Cause: blood tests for infection, HLA B27, ANA, RF
Mx: topical prednisolone / dexamethasone, topical atropine (cycloplegics - ciliary spasm and pain), treat cause
Scleritis vs epislceritis
Red sclera, severe (boring) pain exacerbated by movement, photophobia, excessive lacrimal production, reduced acuity, tenderness
Episcleritis (outermost layer): localised / diffuse redness, no pain, dilated vessels. No photophobia or discharge or change in acuity
Applying phenylephrine drops will cause blanching of vessels and cause redness to disappear, will not help scleritis
Scleritis Px, Mx, associations
Red sclera, severe (boring) pain exacerbated by movement, photophobia, excessive lacrimal production, reduced acuity, tenderness
Mx: urgent referral, systemic steroids, oral NSAIDs (indomethacin), treatment of cause
Associated with connective tissue disorders (RA, vasculitis)
Subconjunctival haemorrhage patho, Px, Mx
Rupture of vessels between sclera and conjunctiva, often after periods of strenuous activity and trauma
RF: hypertension, bleeding disorders, whooping cough, blood thinners
Px: bright red blood covering white of eye, painless and does not affect vision
Harmless + spontaneously resolve, lubrication if irritating, investigate for underlying cause
Corneal abrasion Px, Ix, Mx
Painful red eye, photophobia, foreign body sensation, excessive tear production, blurred vision
Fluorescein stain will collect in abrasion
Treat with topical chloramphenicol (abx), simple analgesia, lubricating eye drops
Keratitis Px, Ix, Mx, most common cause
Primary usually mild blepharoconjunctivitis (eyelid margins + conjunctiva). Painful red eye, vesicles, foreign body sensation, watery discharge, reduced visual acuity
Slit lamp exam, fluorescein staining - dendritic ulcer (branching), corneal scraping for viral testing
Simple Mx: lid hygiene, ocular lubricants, simple analgesia. Can use chloramphenicol + pred
Herpes: urgent referral, topical antiviral, corneal transplant if permanent scarring / vision loss
Herpes simplex most common, potentially sight threatening, in recurrent virus becomes dormant in trigeminal ganglion
Blepharitis Px, Mx
Px: bilateral grittines/ discomfort, particularly around eyelid margins, sticky in the morning, red margins, styes + chalazions common
Mx: hot compresses one eyelid margin BD, lid hygiene to remove debris (boiled water / sodium bicarbonate), artificial tears
Retinitis pigmentosa Px, Ix, Mx
(Genetic condition causing degeneration of photoreceptors (particularly rods))
Px: night blindness often first, peripheral vision loss
Fundoscopy - bone-spicule pigmentation concentrated around the mid-peripheral area, narrowing of arterioles, pale optic disc
Referral to ophthalmology and genetics, vision aids, sunglasses, inform DVLA
No current options to slow progression
Orbital cellulitis pathophysiology, Px, Ix, Mx
Medical emergency (sight threatening), infection of fat and muscles posterior to orbital septum, (not involving globe); usually URTI from sinuses. Most common: strep, staph a, HiB
Risk of cavernous sinus thrombosis, infection spreads, inflammation causes thrombosis (sepsis and cranial nerve palsies)
Px - 5Ps: pain (deep, eye movements), proptosis, periocular swelling (chemosis, erythema), pupil involvement (blurred, diplopia, RAPD), palsy; fever, malaise, other systemic
Ix: exam, FBC, CT with contrast (looking for abscess), blood culture + swab
Mx: admission / senior review, IV abx, surgery for abscess
Periorbital cellulitis Px, Ix, Mx
Px: eyelid swelling + erythema, partial / complete ptosis
Without: pain on movement, ophthalmoplegia, proptosis, visual disturbance, RAPD
Bloods, swab, contrast CT
Mx: oral co-amoxiclav (IV in severe - ceftriaxone), surgery for abscess
Vitreous haemorrhage Px, Ix, Mx
Px: sudden painless vision loss / reduced acuity, floaters. Exam: diminished red reflex, fundoscopy blocked by blood
Ix: slit lamp, B-scan ultrasonography (retinal detachment, foreign bodies, tumours), optical coherence tomography. Looking for cause: fluorescein angiography (vascular abnormalities), FBC + coag, ESR + CRP (vasculitis), viral serology / PCR
Mx: mild - observation and follow up, treat underlying cause (laser photocoagulation for diabetic retinopathy, anti VEGF for wet AMD), vitrectomy for severe / persistent (also treat retinal pathology)
Posterior vitreous detachment Px, Ix, Mx
Px: sudden appearance of of floaters + flashes of light, blurred vision, ‘cobweb’ across vision
Weiss ring on ophthalmoscopy
Ix: examination by ophthalmologist within 24h to rule out retinal tears / detachment
Mx: will resolve in around 6m so no treatment
