Retinal detachment

Question 1

Define retinal detachment.

Answer 1

When the layers of the retina separate – specifically the neurosensory retina from the retinal pigment epithelium. This is a sight-threatening condition and considered an ocular emergency warranting an urgent referral to ophthalmology.

Question 2

How many layers is the retina composed of?

Answer 2

10 - split broadly into neurosensory and retinal pigment epithelium

Question 3

What is the retina bound by?

Answer 3

bruch’s membrane
choroid (externally)
vitreous (internally)

Question 4

What is the aetiology of retinal detachement?

Answer 4

Rhehmatogenous retinal detachment - secondary to full thickness retinal tear, vitreous fluid builds up behinf the neurosensory retina

Causes:
Tractional - vitreous pull on the retina; there are no holes or tears; common in diabetic retinopathy
Exudative - retinal disease causes build up of exudative fluid e.g. tumours or posterior scleritis

NB: posterior vitreous detachment often preceded retinal detachment (vitreous gel separating from the retina due to trauma or ageing), which later develops into a retinal tear and full retinal detachment if untreated.

Question 5

What are the risk factors for retinal detachment?

Answer 5

• Age >40
• Male
• Myopia (near-sightedness)
• Family history of retinal detachment
• Previous ocular surgery
• Trauma
• Retinal detachment in the contralateral eye

These are the risk factors for rhegmatogenous (most common)

Question 6

What are the clinical features of retinal detachment?

Answer 6

• Painless loss of vision
• Flashing lights and floaters
• “Cobwebs” in the peripheral vision
• Shadow or grey curtain moving across the field of vision

O/E:

• Poor visual acuity
• RAPD
• Altered red reflex (grey or folded appearance)
• Reduced visual acuity (if the macula is involved)
• Visual field defects
• A sheet of sensory retina billowing towards the centre of the globe

Question 7

How do you diagnose retinal detachment?

Answer 7

Slit lamp examination with triple mirror - assess for anterior breaks; ‘Tobacco dust’ appearance of the anterior vitreous: a result of pigment cells migrating through a tear in the retina (also known as Shafer’s sign)

Indirect ophthalmoscopy - shows location and number of retinal tears and the amount of underlying fluid.

Visual assessment - poor acuity, red reflex becomes grey, deficits in visual field

Ultrasound - if there is a vitreous haemorrhage caused by tear involving a retinal vessel

Question 8

What is Shafer’s sign?

Answer 8

tobacco dust appearance of the anterior vitreous due to pigemnt cells migrating through a tear in the retina

Question 9

What are some differentials for retinal detachment?

Answer 9

Retinoschisis: split within the neurosensory layer (no Tobacco dust sign or corrugated appearance on fundoscopy)
Choroidal mass : solid mass associated with fluid which varies with the head’s position (no retinal tear or pigment in the vitreous)

Question 10

What are the complications and prognosis of retinal detachment?

Answer 10

Partial or complete loss of unilateral vision
If involving the macula then it has the worst prognosis with poorest visual outcomes

Question 11

What is the management of retinal detachment?

Answer 11

Prevention - if symptomatc then urgently refer and treat tears with laser photocoagulation to stop detachment from occurring. Most are found at this point.

Surgical:

• Virectomy - most common treatment of RD; vitreous is drained so retina can lie falt against epithelium and cryotherapy or laser is used to seal it; eye is filled with air/gel to stick
• Pneumatic retinopexy - for simple cases; gas injected into vitreous to flatten it and laser or cryotherapy retinopexy is used to create adhesive scae to prevent re-entry
• Scleral buckle - cryotherapy or laser to scar the retinal break then silicone band is sutured into sclera. Less common.