Opthalmology Flashcards
1
Q
Afferent Defect
A
Features -
- No direct response but intact consensual response
- Cannot initiate consensual response in contralateral eye.
- Dilatation on moving light from normal to abnormal eye
Causes
- Total CN II lesion
2
Q
Relative Afferent Pupillary Defect
A
= Marcus-Gunn Pupil Features
Features
- Minor constriction to direct light
- Dilatation on moving light from normal to abnormal eye
Causes
- Optic neuritis
- Optic atrophy
- Retinal disease
3
Q
Efferent Defect
A
Feature
- Dilated pupil does not react to light
- Initiates consensual response in contralateral pupil
- Ophthalmoplegia + ptosis
Cause
- 3rd nerve palsy
- The pupil is often spared in a vascular lesion (e.g. DM) as pupillary fibres run in the periphery.
4
Q
Differential of a fixed dilated pupil
A
- Mydriatics: e.g. tropicamide
- Iris trauma
- Acute glaucoma
- CN3 compression: tumour, coning
5
Q
Holmes-Adie Pupil
A
Features
- Young woman c¯ sudden blurring of near vision
- Initially unilateral and then bilateral pupil dilatation
- Dilated pupil has no response to light and sluggish response to accommodation.
- A “tonic” pupil
Ix
- Iris shows spontaneous wormy movements on slit-lamp examination
- Iris streaming
Cause
- Damage to postganglionic parasympathetic fibres
- Idiopathic: may have viral origin
Holmes-Adie Syndrome - Tonic pupil + absent knee/ankle jerks + ↓ BP
6
Q
Horner’s Syndrome
A
Features:
- PEAS
- Ptosis: partial (superior tarsal muscle)
- Enophthalmos
- Anhydrosis
- Small pupil
Causes
- Central -MS, Wallenberg’s Lateral Medullary Syndrome
- Pre-ganglionic (neck), Pancoast’s tumour: T1 nerve root lesion, Trauma: CVA insertion or CEA
- Post-ganglionic, Cavernous sinus thrombosis, Usually 2O to spreading facial infection via the ophthalmic veins, CN 3, 4, 5, 6 palsies
7
Q
Argyll Robertson Pupil
A
Features
- Small, irregular pupils
- Accommodate but doesn’t react to light
- Atrophied and depigmented iris
Cause
- DM
- Quaternary syphilis
8
Q
Acute Closed Angle Glaucoma
(RED EYE)
A
- Blocked drainage of aqueous from anterior chamber via angle of Schlemm
- Pupil dilatation (e.g. at night) worsens the blockage, IOP ->60mmHg
- RFs - hypermetropia, shallow anterior chamber, female, FH, increased age, drugs (anti-cholinergics, sympathomimetics, TCAs, anti-histamines)
-
Symptoms - prodrome = ranbow haloes around lights at night
- Severe pain, +/- N/V
- Decreased acuity, blurred vision
-
Examination - cloudy cornea +/- circumcorneal injection
- Fixed, dilated, irregular pupil
- Increase IOP -> hard feeling eye
- Ix - Tonometry - V V high IOP (>40mmHg)
-
Acute Mx -
- Pilocarpine 2-4% drops - miosis opens blockage
- Topical beta-blockers e.g. timolol - decrease aqueous formation
- Acetazolamide 500mg IV stat - decrease aqueous formation
- Analgesia and antimetics
-
Subsequent Mx -
- Bilat YAG peripheral iridotomy once IOP decreases
9
Q
Sudden Loss of Vision
Key Questions
A
- Headache associated - GCA
- Eye movements hurt - optic neuritis
- Lights/flashes preceding visual loss - detached retina
- Like curtain descending - TIA, GCA
- Poorly controlled DM - vitreous bleed from new vessels
10
Q
Sudden Loss of Vision
AION
A
- Optic nerve damaged if posterior ciliary arteries blocked by inflammation or atheroma.
- Pale / swollen optic disc
-
Causes
- Arteritic AION: Giant Cell Arteritis
- Non-arteritic AION: HTN, DM, ↑ lipids, smoking
11
Q
Sudden Loss of Vision
OPTIC NEURITIS
A
-
Symptoms
- Unilateral loss of acuity over hrs – days
- ↓ colour discrimination (dyschromatopsia)
- Eye movements may hurt
-
Signs
- ↓ acuity
- ↓ colour vision
- Enlarged blind-spot
- Optic disc may be: normal, swollen, blurred
- Afferent defect
-
Causes
- Multiple sclerosis (45-80% over 15yrs)
- DM
- Drugs: ethambutol, chloamphenicol
- Vitamin deficiency
- Infection: zoster, Lyme disease
-
Rx
- High-dose methyl-pred IV for 72h
- Then oral pred for 11/7
12
Q
Sudden Loss of Vision
VITREOUS HAEMORRHAGE
A
-
Source
- New vessels: DM
- Retinal tears / detachment / trauma
-
Presentation
- Small bleeds → small black dots / ring floaters
- Large bleed can obscure vision → no red reflex, retina can’t be visualised
-
Ix
- May use B scan US to identify cause
-
Mx
- VH undergoes spontaneous absorption
- Vitrectomy may be performed in dense VH
13
Q
Sudden Loss of Vision
CENTRAL RETINAL ARTERY OCCLUSION
A
-
Presentation
- Dramatic unilateral visual loss in seconds
- Afferent pupil defect (may precede retinal changes)
- Pale retina c¯ cherry-red macula
-
Causes
- GCA
- Thromboembolism: clot, infective, tumour
- GCA
-
Rx
- If seen w/i 6h aim is to ↑ retinal blood flow by ↓ IOP
- Ocular massage
- Surgical removal of aqueous
- Anti-hypertensives (local and systemic)
14
Q
Sudden Loss of Vision
RETINAL VEIN OCCLUSION
A
-
Central
- Commoner than arterial occlusion
- Causes: arteriosclerosis, ↑BP, DM, polycythaemia
- Pres: sudden unilat visual loss c¯ RAPD
-
Fundus: Stormy Sunset Appearance
- Tortuous dilated vessels
- Haemorrhages
- Cotton wool spots
-
Complications
- Glaucoma
- Neovascularisation
- Prognosis: possible improvement for 6mo-1yr
-
Branch
- Presentation: unilateral visual loss
- Fundus: segmental fundal changes
- Comps: retinal ischaemia → VEGF release and neovascularisation
- Rx: laser photocoagulation
15
Q
Sudden Loss of Vision
RETINAL DETACHMENT
A
- Holes/tears in retina allow fluid to separate sensory retina from retinal pigmented epithelium
- May be 2O to cataract surgery, trauma, DM
-
Presentation: 4 F’s
- Floaters: numerous, acute onset, “spiders-web”
- Flashes
- Field loss
- Fall in acuity
- Painless
- Fundus: grey, opalescent retina, ballooning forwards
-
Rx
- Urgent surgery
- Vitrectomy + gas tamponade c¯ laser coagulation to secure the retina.
