OPH - Retinal Conditions

Question 1

Posterior Vitreous Detachment

Vitreous Body
Pathophysiology
Clinical Features
Management

Answer 1

1. ) Vitreous Body - maintains structure of the eyeball
   - holds the retina in place and supports the lens and
   - contains gel: made up of water (99%) and collagen
2. ) Pathophysiology - vitreous detaches from the retina
   - very common in the elderly (part of ageing process)
   - ↑age –> vitreous body becomes less firm and unable to maintain its shape causing fluid to fill between the potential space between the retina and the vitreous
   - other risk factors: eye trauma, myopia, diabetes
3. ) Clinical Features - can be asymptomatic or:
   - painless, dark spots of vision loss
   - photopsia (in peripheral vision)
   - floaters (on temporal side of the central vision), moves with eye movements, there constantly
4. ) Management - no treatment is necessary
   - sx improve overtime as the brain adjusts
   - complications: retinal tears, retinal detachment, vitreous haemorrhage
   - fundoscopy/ocular ultrasound/OCT: to assess the risk of a retinal tear or detachment

Question 2

Retinal Detachment

Pathophysiology
Risk Factors
Clinical Features
Management

Answer 2

1. ) Pathophysiology - separation of the neural retina from the retinal pigment epithelium (RPE)/choroid)
   - often due to a retinal tear which allows vitreous fluid to enter the space between the retina and the choroid
   - outer retina receives blood supply from the choroid making detachment a sight-threatening emergency
2. ) Risk Factors
   - ↑age, FH, diabetic retinopathy, myopia
   - eye trauma (rhegmatogenous retinal detachment)
   - posterior vitreous detachment, retinal malignancy
3. ) Clinical Features - sudden painless loss of vision w/:
   - floaters and flashing lights (spiderweb-like)
   - dense shadow starting peripherally and progressing centrally
   - floaters do not move with eye movements
   - ↓visual acuity, blurred/distorted vision
   - visual field impairment depending on the area
   - straight lines can often appear irregular or curved due to the retina sagging away from the choroid
   - may have absent red (fundal) reflex
4. ) Management - ophthalmological emergency
   - permanent blindness if progresses to the macula
   - fundoscopy/ocular ultrasound/OCT: for imaging
   - requires surgery to reattach the retina and fix any retinal tears

Question 3

Surgical Methods for Retinal Detachment

Vitrectomy
Scleral Buckling
Pneumatic Retinopexy
Management of Retinal Tears

Answer 3

1. ) Vitrectomy - removing the relevant parts of the vitreous body and replacing it with oil or gas
   - safest and most common procedure
2. ) Scleral Buckling - use a silicone “buckle” to apply pressure on the sclera so the outer eye indents
   - this brings the choroid into contact w/ the retina
   - used in younger patients (30s) and in patients that do not have posterior vitreous detachment
3. ) Pneumatic Retinopexy - inject gas bubble into the vitreous body to create pressure flattening the retina
   - dangerous outdated method, rarely used
4. ) Management of Retinal Tears - create adehsions between retina and choroid to prevent detachment
   - can be done using laser therapy or cryotherapy

Question 4

Retinal Vein Occlusion

Pathophysiology
Risk Factors
Clinical Features
Management

Answer 4

1. ) Pathophysiology - thrombus forms, blocks drainage of blood from the retina –> blood pooling in the retina
   - leakage of fluid and blood causes macular oedema and retinal haemorrhages, causing damage to tissue in the retina and also causing neovascularization (↑VEGF)
   - can be one of 4 branched veins or the central retinal vein which causes problems with the whole retina
2. ) Risk Factors
   - smoking, hypertension, diabetes, high cholesterol
   - glaucoma, polycythaemia, inflammatory conditions e.g. SLE
3. ) Clinical Features - sudden painless loss of vision
   - fundoscopy: severe flame and blot haemorrhages, cotton wool spots, tortuous veins, optic disc oedema and macula oedema

4.) Management - emergency referral to ophthalmology
- other tests: full medical history, FBC (leukaemia),
ESR (inflammatory disorders), BP (HTN), BM (diabetes)
- laser photocoagulation, intravitreal steroids (e.g. a dexamethasone intravitreal implant)
- Anti-VEGF therapies (e.g. ranibizumab, aflibercept)

Question 5

Central Retinal Artery Occlusion

Pathophysiology
Clinical Features
Immediate Management
Long Term Management

Answer 5

1. ) Pathophysiology - blockage of central retinal artery occludes blood supply to the retina
   - ICA –> ophthalmic artery –> central retinal artery
   - most common cause is atherosclerosis but can also be caused by giant cell arteritis
   - risk factors: ↑age, FH, smoking, alcohol, HTN, DM, obesity, GCA: PMR, women, white-caucasian
2. ) Clinical Features - sudden painless loss of vision
   - fundoscopy: pale retina (↓perfusion) with a cherry-red spot (thinner macular surface shows red choroid below)
   - relative afferent pupillary defect: pupil in the affected eye constricts more when light is shone in another eye
3. ) Immediate Management - emergency referral to ophthalmology, exclude GCA: especially older patients
   - attempt to dislodge the thrombus:
   - ocular massage
   - remove fluid from the anterior chamber to ↓IOP
   - inhaling carbogen (5% CO2, 95% O2) to dilate artery
   - sublingual isosorbide dinitrate to dilate the artery

4.) Long Term Management - treating reversible risk factors and secondary prevention of CVD

Question 6

Optic Neuritis

Pathophysiology
Clinical Features
Management

Answer 6

1. ) Pathophysiology - damage to the optic nerve
   - most common cause is MS (more common in women)
   - other causes include:
   - diabetes, SLE, sarcoidosis
   - syphilis, Lyme disease, measles, mumps
2. ) Clinical Features
   - unilaterally reduced visual acuity over hours to days
   - periocular pain: pain on eye movement, the pain feels like it is behind the eye
   - dyschromatopsia: deficiency in colour perception
   - absent direct light reflex (pupils do not constrict)
   - RAPD, central scotoma (enlarged blind spot)
   - may have papilledema
   - ?MS sx: paraesthesia, weakness etc…
3. ) Management
   - high-dose PO (or IV) methylprednisolone for 5 days
   - contrast sensitivity, colour vision and visual fields can remain impaired even after recovery of visual acuity
   - 50% of patients with a single episode of optic neuritis will go on to develop MS over the next 15 years
   - referral to neurology for an MRI contrast of the brain and spinal cord

Question 7

Vitreous Haemorrhage

Pathophysiology
Clinical Features
Investigations

Answer 7

1. ) Pathophysiology - bleeding into the vitreous humour from disruption of retinal vessels or nearby vessels
   - causes: diabetes (PDR), vitreous detachment, trauma
   - other RF: HTN, anti-coagulants, bleeding disorders, severe myopia
2. ) Clinical Features - sudden painless loss of vision
   - typically an acute or subacute onset
   - floaters or shadows/dark spots in the vision
   - ↓visual acuity, red hue to vision
   - visual field defect if severe
   - may have absent red (fundal) reflex
3. ) Investigations
   - fundoscopy: haemorrhage in the vitreous cavity
   - slit-lamp: RBCs in the anterior vitreous
   - ultrasound: exclude retinal tear/detachment
   - fluorescein angiography: identify neovascularization
   - orbital CT: used if open globe injury