Sudden Loss of Vision: NAION, GCA, AACG, Retinal Detachment

Question 1

NAION

• pathophysiology, risk factors
• presentation
• investigations
• management and prognosis

Answer 1

Occlusion of short post ciliary arteries => optic nerve head infarction

Male, 40-60
CV risk factors - systemic arteriopathy, HTN, DM
Small optic disc

Presentation - PAINLESS, 1 eye, sudden loss
RAPD
Visual acuity - reduced
Visual fields - loss in swollen area (most common in inf quadrants)
Fundoscopy - optic nerve swollen, splinter/flame hemorrhages
Palpate temporal arteries - GCA assessment - painful temples

Urgent opthalmology => rule out GCA (ESR, CRP)
Manage CV risk factors

Vision gradually improves but optic pallor remains due to loss of neural tissue
May affect other eye

Question 2

GCA

• pathophysiology
• risk factors
• presentation
• investigations
• management

Answer 2

Medium, large vessel vasculitis affecting scalp, head, neck => ant ischemic optic neuropathy

Female, 50+, PR

Before - transient visual loss
Headache, scalp tenderness, jaw pain
Loss of appetite, weight loss
PAINFUL, sudden loss, 1 eye => may lead to blindness within hours

Palpation - non pulsatile tender temporal arteries
RAPD
Visual acuity - counting fingers
Visual field - poorer vision
Fundoscopy - swollen optic disc, flame hemorrhage, cotton wool spots (site of infarction)

Emergency opthalmology referral -

• High ESR, CRP => high CS
• temporal artery biopsy

Question 3

Acute angle closure glaucoma

• pathophydiology
• risk factors
• presentation
• investigation findings
• management

Answer 3

AACG - inability to drain aqueous humour => IOP

• iris pushed forwards => blocks trabecular meshwork
• aqueous humour cannot pass through pupil

FHx
Female
30+ - lens thickens
Long-sighted - smaller eyes have a narrower angle between iris or cornea
Narrow ant chamber angles

Previous intermittent symptoms
1 eye - vision loss, red painful 
Halo around light
N+V
Can be asymptomatic

Corneal edema
Rock hard eye on palpation
Reflexes - unreactive pupil
Visual acuity - reduced

Opthalmic emergency
Reduce IOP - acetazolamide, timolol and apraclonidine drops
Definitive - iridotomy

Question 4

Aqueous humour drainage anatomy and physiology

Answer 4

Ciliary body in post chamber produces aqueous humour => enters ant chamber via pupil => leaves via trabecular meshwork => bloodstream

Question 5

Retinal anatomy and physiology

-how our retina changes as we age

Answer 5

2 main layers
-neurosensory retina
-retinal pigment epithelium
Vitreous attached to retina

Vitreous naturally separates from retina as we age

Question 6

Retinal detachment

-types of retinal detachment

Answer 6

Post vitreous detachment - vitreous separates from retina

Rhegmatogenous retinal detachment - vitreous fluid enters tear between neurosensory and RPE
Tractional retinal detachment - retinal scar tissue contracts => separating neurosensory retina and RPE
Serous retinal detachment - exudate collects between neurosensory and RPE

Question 7

Retinal detachment

• risk factors
• presentation
• investigations
• management

Answer 7

Short sighted
Trauma

Photopsia - retinal stimulation sends off impulses seen as flashes
Large no of floaters - shadows cast on the retina

RAPD - large RD
Visual field loss - in area of retinal detachment
Visual acuity loss - central loss indicates macula involvement
Fundoscopy - dilate iris with phenylephrine+tropicamide (unless Hx of AACG) => assess for tears, PVD

RD => opthalmic emergency, treat before macula detaches
-cryobuckle surgery, pars plana vitrectomy