Retinal Detachment

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Introduction

Retinal detachment occurs 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.


Anatomy

The retina is a structure of cells lining the back of the eye (Figure 1). It is comprised of 10 separate layers which can be broadly split into the inner neurosensory retina and the outer retinal pigment epithelium.

Within the neurosensory retina lies the photoreceptors (rods and cones) which are responsible for converting light into neural impulses, which are then transmitted to the brain for the formation of images. The retina is bound by Bruch’s membrane, the choroid (externally) and the vitreous (internally).

anatomy of retina
Figure 1. Anatomy of the eye, including retina1

Aetiology

Retinal detachment most commonly occurs secondary to a full-thickness retinal tear which enables the build-up of vitreous fluid behind the neurosensory retina.2 This is known as a rhegmatogenous retinal detachment (Figure 2).

Other causes/types of retinal detachment can be classed as follows:

  • Tractional: vitreous membranes pull on the retina which separates it from the epithelial layer beneath. There are no tears or holes formed. This is more common in patients with diabetic retinopathy.
  • Exudative: an underlying retinal disease leads to the build-up of exudative fluid underneath the retina (e.g. exudative tumours, inflammation and posterior scleritis).

Of note, posterior vitreous detachment (PVD) often precedes retinal detachment. This is where the vitreous gel separates from the retina and is due to trauma or ageing. About 1 in 10 will go on to develop a retinal tear, which if left untreated will develop into a full retinal detachment.3

retinal detachment
Figure 2. Rhegmatogenous retinal detachment4

Risk factors

Risk factors for rhegmatogenous retinal detachment (most common), include:

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

Clinical features

History

Typical symptoms of retinal detachment include:

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

Clinical examination

In the context of suspected retinal detachment a complete assessment of the eyes and vision should be performed.

Clinical findings may include:

  • Poor visual acuity
  • Relative afferent pupillary defect
  • 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

Slit lamp examination may reveal a ‘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)


Differential diagnoses

Possible differential diagnoses in the context of suspected retinal detachment include:

  • 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)

Investigations

Further investigation under a slit lamp with a triple mirror is used to assess for anterior breaks (Figure 3).

Indirect ophthalmoscopy will also reveal the location and number of retinal tears and the amount of underlying fluid.

Ultrasound can also be used if there is a vitreous haemorrhage caused by a tear involving a retinal vessel.

horseshoe retinal tear
Figure 3. Horseshoe retinal tear causing retinal detachment5

Management

Preventative management

Patients with symptoms of an acute PVD or a retinal tear should be examined without delay. If a retinal tear is found, this can be treated with laser photocoagulation in the clinic and to reduce the risk of a detachment occurring.

The majority of cases are treated at this point and do not progress to a retinal detachment.

Surgical management

There are three main surgical techniques for managing retinal detachment.

Vitrectomy

Vitrectomy is the most common treatment of RD.

The vitreous (the gel that fills the inside of the eye) and the subretinal fluid are drained, which allows the retina to lie flat against the underlying epithelium.

Cryotherapy or laser therapy is used to seal the retinal tear and the eye is then filled with an absorbing gas, air or silicone oil bubble to hold it in place.

This technique also requires the patient to maintain a head position after surgery with post-op patients unable to fly for 3-6 months and not suitable for any anaesthetics involving nitric oxide.

Pneumatic retinopexy

Pneumatic retinopathy is suitable for straightforward cases and involves a 2-step process.

An expansile gas is injected into the vitreous which flattens and pushes the retina back onto the underlying epithelium.

Laser or cryotherapy retinopexy then creates an adhesive scar which holds the retina in place and prevents the vitreous fluid re-entering the space behind.

This procedure can be performed in-clinic but requires the patient to maintain a specific head position for several days to ensure reattachment occurs.

Scleral buckle

Cryotherapy or laser photocoagulation is used to create a scar around the retinal break.

A silicone band is then sutured onto the sclera, and this indents the retina to close the retinal break and relieve traction.

The scleral buckle remains around the eye permanently in most cases.

This technique is now less common, although can be applied following retinal dialysis (a circumferential break often caused by blunt trauma) (Figure 4).

scleral buckle
Figure 4. Scleral buckle sutured around the eye to indent the retina and close the break6

Complications

Complications of retinal detachment include:

  • Partial or complete unilateral vision loss

Retinal detachment involving the macula carries the worst prognosis and results in the poorest visual outcomes.


Key points

  • Retinal detachment is an ocular emergency requiring urgent ophthalmology consult.
  • It is characterised by a painless loss of vision and patients complaining of peripheral ‘flashers and floaters’.
  • Surgical management involves reattaching the retina to the underlying epithelium via laser or cryotherapy.

References

  1. OpenStax College. Structure of the eye. Published in 2013. Licence: [CC BY-3.0]. Available from: [LINK]
  2. Timothy L. Jackson. Moorfields Manual of Ophthalmology. Published in 2008. Available from: [LINK]
  3. The Royal College of Ophthalmologists. Posterior vitreous detachment. Published in 2017. Available from: [LINK]
  4. Erin Silversmith. Human eye cross-section detached retina. Licence: [CC BY-3.0]. Available from: [LINK]
  5. Jesse Vislisel, MD. Rhegmatogenous retinal detachment. Licence: [CC BY-3.0]. Available from: [LINK]
  6. Erin Silversmith. Human eye cross-section scleral buckle. Licence: [CC BY-3.0]. Available from: [LINK]

Reviewer

Mr Kashani

Consultant Ophthalmologist


Editor

Hannah Thomas


 

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