Retinal detachment

Retinal detachment (RD) involves the neurosensory layer of the retina separating off from the underlying retinal pigment epithelium (RPE).

Most retinal detachments are preceded by a posterior vitreous detachment (PVD), which causes traction on the retina and, potentially, a retinal tear. The liquefied vitreous can then seep under the retina, causing it to detach. Retinal detachments may initially be localised, but without treatment they may progress and lead to irreversible vision loss. Early recognition and prompt referral are therefore essential^{1 2} .

Classification

Rhegmatogenous RD

This follows a retinal break usually caused by PVD. Liquefied vitreous seeps through the break between the sensory retina and the pigment epithelium, lifting the retina off. This is the most common form of RD.

Non-rhegmatogenous RD

• Exudative (serous, or secondary RD): primary damage of the underlying RPE allows subretinal fluid to leak into the subretinal space, pushing the retina off.

• Tractional: fibres in the vitreous contract, pulling the sensory retina away. This is an uncommon form of RD.

Epidemiology^{2 3 4}

• Retinal detachment has an annual incidence of 10-15 per 100,000 people.

• Incidence increases with advancing age.

• Lifetime risk is estimated to be 3% at 85 years of age.

• Average age of presentation is 60 years.

• It is unusual in younger people, although traumatic RD is more common in younger patients, particularly men.

• There has been an increase in presentation of much younger individuals, associated with paintball injuries⁵ .

• It is more frequent in right eyes and with increasing affluence.

• Men and women are similarly affected

• After RD the risk of RD in the contralateral eye is around 10%.

• There are an estimated 7,300 new cases in the UK every year.

• There is anecdotal evidence that it is more common in people of Jewish descent and less common in patients of African origin.

Aetiology^{6 7}

• Rhegmatogenous RD: in most cases, RD is preceded by a PVD - usually resulting from age-related degenerative liquefaction and shrinkage of the vitreous. PVD leads to retinal tear in 10-15% of cases. Of these, asymptomatic new retinal breaks lead to detachment in about 5% of cases but symptomatic new retinal breaks progress to detachment in 50% of cases.

• Exudative (or serous) RD: results from the accumulation of serous and/or haemorrhagic fluid in the subretinal space because of hydrostatic factors (eg, severe acute hypertension), inflammation (eg, sarcoid uveitis), or neoplastic effusions. Exudative RD generally resolves with successful treatment of the underlying disease. Visual recovery is often excellent.

• Tractional RD: occurs via mechanical forces on the retina, usually mediated by fibrotic tissue resulting from previous haemorrhage, injury, surgery, infection, or inflammation. Correction of tractional RD requires disengaging scar tissue from the retinal surface.
  

Risk factors for RD²

Risk factors vary with the type and site of detachment but include:

• Myopia: this increases the risk of PVD, as the eyeball is longer and the peripheral retina thinner and more likely to tear. A correction of more than −3 dioptres carries a ten-fold risk¹ .

• Family history of retinal break or detachment: there may be a tendency towards inherited myopia or degenerative retinal lesions.

• Previous history of retinal break or detachment in either eye: about 12% of people with RD develop subsequent detachment in the fellow eye.

Risk factors for rhegmatogenous RD

• Age.

• Lattice degeneration (see below).

• Aphakia.

• Age-related retinoschisis.

• Previous retinal break.

• Marfan's syndrome.

• Previous cataract surgery accelerates PVD. RD occurs in approximately 1% of people in the weeks to years after cataract surgery. Previous complicated cataract surgery substantially increases the risk of subsequent RD.

Risk factors for non-rhegmatogenous tractional RD
Fibrous bands in the vitreous may occur in conditions such as:

• Proliferative diabetic retinopathy.

• Penetrating eye injury.

• Retinal vein occlusion.

• Retinopathy of prematurity.

• Previous giant retinal tear.

• Sickle cell retinopathy.

• Toxocariasis.

• Blunt eye trauma; there may be a latent period of several months to years before RD occurs.

Risk factors for non-rhegmatogenous exudative RD

• Inflammatory conditions - eg, uveitis, posterior scleritis.

• Vascular disease - eg, severe hypertension, Coats' disease.

• Toxaemia of pregnancy.

• Congenital abnormalities - eg, coloboma.

• Maculopathy - eg, wet age-related macular degeneration (RD associated with intravitreal anti-vascular endothelial growth factor (anti-VEGF) is very uncommon)⁸ .

• Malignancy (for example, choroidal melanoma or ocular metastasis) - predisposes to exudative RD.

Lattice degeneration

This condition, present in around 10% of the population, involves the peripheral retina becoming thinned or atrophic in a lattice pattern. It may then be prone to tears, breaks, or holes, which may further progress to RD. It is an important cause of RD in young myopic individuals. Lattice degeneration is typically bilateral.

Presentation^{2 7}

A careful history can help distinguish retinal detachment from other conditions with similar symptoms.

History

• New onset of floaters (perception of mobile dots, lines, or haze due to blood and pigment cells entering the vitreous cavity casting shadows on the retina):

  • Floaters caused by acute PVD, especially in the presence of a retinal tear, occur more abruptly and dramatically than the floaters that people experience for much of their lifetime. Similar floaters occur with other causes of intraocular bleeding, such as proliferative diabetic retinopathy, trauma and ocular inflammation (uveitis).

• New onset of flashes (seen as recurrent, brief flashes, often more noticeable in low light conditions, caused by traction on the retina as the vitreous pulls away):

  • Light flashes may precede migraine headaches but these typically occur bilaterally (although often in one area of the visual field). Photopsia induced by eye movements may indicate optic neuritis. Light flashes also may occur with postural hypotension and vasovagal reactions; these are bilateral and often accompanied by temporary dimming of vision and light-headedness.

• Sudden-onset painless, usually progressive, visual field loss. This may be described as a dark curtain or shadow, which usually starts in the periphery and progresses towards the centre over hours, days, or weeks. If the macula detaches, central visual acuity is severely reduced:

  • Visual field loss begins suddenly, usually in the periphery; it progresses towards the central visual axis over hours to weeks. Field loss caused by stroke or other central nervous system processes is always bilateral, stable, and homonymous, due to crossing of nasal retinal projections at the optic chiasm. Even in patients with severe field loss caused by cerebral disease, the macula is spared and central vision persists. Visual loss from a transient ischaemic attack may be unilateral; however, it is not persistent or progressive and may be accompanied by other neurological symptoms. Fixed field defects of variable size occur in patients with retinal vascular occlusion; these patients lack acute flashes and floaters.

• It is more difficult to recognise RD in children, as they are less likely to complain about reduced vision or visual disturbance. In older children, most RD is secondary to a history of trauma. Infants usually present with a white pupillary reflex (leukocoria) or squint (strabismus).

Examination^{2 7}

See also the separate Examination of the Eye article.

Pupillary reflexes

• Look for a relative afferent pupillary defect (RAPD) using a swinging light. In healthy eyes, a bright light shone into one eye leads to an equal constriction of both pupils. When the light is taken away, the pupils of both eyes enlarge equally. When there is an RAPD the affected pupil appears to dilate rather than constrict when light is shone on it (as it constricts better when light is shone on the other eye). A positive RAPD means there is a defect in afferent pathway in the affected eye due to retinal or optic nerve disease. In RD, RAPD typically occurs if the macula is detached or if at least two quadrants of the non-macular retina have detached.

• There may be an altered red reflex, with a grey or folded appearance.

Visual acuity

• This should be checked in all patients. If you suspect an RD and visual acuity is normal, this suggests that the macula is still attached.

• A poor visual acuity suggests that the macula has already become detached. It may also suggest a vitreous haemorrhage.

Visual fields
Confrontational visual field testing may reveal gross visual defects corresponding to the area of detached retina, although early defects may be too small and peripheral to be clearly detectable.

Dilated fundal examination
NB: only do this after you have assessed the visual acuity and ruled out the presence of an RAPD.

• Dilate the pupils with 1% tropicamide; warn the patient that their vision will become blurred and so they will not be able to drive for 2-3 hours.

• A large detachment can be seen as a sheet of sensory retina billowing towards the centre of the globe, over which the vessels pass like paths over a hill.

• There may be an associated tear visible.

• Because its view is narrow, examination with the direct ophthalmoscope cannot exclude RD. If you cannot see an RD but suspect it, refer the patient urgently for a slit-lamp examination.

• If you have access to a slit lamp, look for cells in the anterior chamber and the presence of 'tobacco dust', seen as grey-red specks just behind the pupil. This is associated with a 90% risk of a retinal break. A vitreous haemorrhage is associated with a 70% risk of a retinal break.

Assess both eyes⁹
Always ask about - and assess - the other eye. RD is usually a unilateral condition but there may be detachments in both eyes.

Differential diagnosis^{2 7}

Conditions with similar symptoms

• Photopsia:
  

  • PVD - which may lead to RD.

  • Atypical/ocular migraine.

  • Optic nerve pathology - eg, optic neuritis.

  • Cerebrovascular event/transient ischaemic attacks.

  • Choroidal tumours.

• Floaters:
  

  • PVD.

  • Vitreous haemorrhage

  • Age-related macular degeneration.

  • Uveitis (particularly posterior).

  • Retinitis pigmentosa.

Conditions with similar signs

• Retinoschisis: usually a benign condition where the retina is split into layers.

• Choroidal detachment: detachment of the vascular layer of the eye.

• Uveal effusion syndrome: rare idiopathic condition characterised by self-limiting choroidal and retinal detachment.

Investigations⁷

• Examination in the eye department will involve a slit-lamp examination, indirect ophthalmoscopy or Goldmann triple mirror examination (which involves a slit lamp and a contact lens applied against the anaesthetised cornea for a few minutes as the peripheral retina is examined).

• Ultrasound or optical coherence tomography may be used to assess the type and extent of the detachment, any associated tears and any ocular comorbidity.

• CT and MRI scans have a role if there is a tumour or suspected foreign body.

• Patients with an exudative RD benefit from a full systemic examination, owing to its association with systemic disease.

Referral^{2 6}

Patients with a suspected RD should be seen by a specialist on the same day. The urgency of specialist assessment depends on your assessment and clinical suspicion, whether there are changes in visual acuity, visual field loss, or signs seen on fundoscopy.

• If there is a visual field defect but visual acuity is good, referral is urgent, as it is likely to be a 'macula-on' RD (the macula is still adherent to the underlying RPE) as opposed to a 'macula-off' detachment (where surgery is a rescue procedure rather than a protective one).

• If there are new-onset flashes and/or floaters, refer them immediately if there are signs of threat to sight, such as:

  • Visual field loss (such as a dark curtain or shadow), or distorted or blurred vision.

  • Fundoscopic signs of RD or vitreous haemorrhage.

• If the person is experiencing new-onset flashes and/or floaters, refer them to be seen within 24 hours as long as there is:

  • No visual field loss.

  • No change in visual acuity.

  • No fundoscopic sign of RD or vitreous haemorrhage.

Management

Cryotherapy/laser photocoagulation

Retinal tears and holes are treated with cryotherapy or laser photocoagulation. This achieves permanent adhesion between the retina and RPE. In around 95% of cases this prevents further accumulation of fluid through retinal breaks and stops progression to RD.

Surgery for RD is performed by specialist vitreoretinal surgeons.

• Most RDs not involving the macula are repaired the same day and those involving the macula are repaired within five days.

• Those patients who do not have immediate surgery may be advised to have strict bedrest and to hold the head in a particular position to prevent progression of the detachment.

• Surgery may be carried out under a local or general anaesthetic, depending on the type of repair undertaken and on the patient's fitness.

• The rate of evolution of RD is a key factor when scheduling emergency surgery, and where there is imminent danger that the fovea is about to detach, surgery must be carried out urgently. Where there is a low risk of progression to involve the fovea, it may be better to use posturing and bed rest, organising surgery for when the appropriate skill mix of the theatre team can be assembled

Three surgical techniques are used to reattach the retina. The first two are more commonly chosen:

Vitrectomy

This is performed to relieve traction. Air, gas or silicone oil is injected into the vitreous space to help flatten the retina. Air or gas may be reabsorbed slowly; oil is sometimes removed later. This technique is also now increasingly used in rhegmatogenous RD. Vision post-vitrectomy may remain impaired for weeks or months.

Scleral buckling¹⁰

A piece of silicone material is placed on the scleral surface, secured under the conjunctiva. This indents the wall of the eye, pushing it closer to the detached retina. This alteration in the relationships of the tissues seems to allow the fluid which has formed under the retina to be pumped out and helps the retina to re-attach. Diplopia is an occasional complication. Scleral buckling techniques achieve reattachment in over 90% of cases. If there is a large RD or multiple tears or holes, a band of silicone may be placed all around the outside of the eye, like a belt.

Pneumatic retinopexy¹¹

A small expansile gas bubble is injected into the vitreous cavity. It expands over 1-3 days, and can be positioned to close the retinal break, again allowing the fluid to be pumped out and encouraging reattachment.This procedure is favoured in North America and less commonly used in the UK. It is only suitable for a minority of straightforward cases. The person may be instructed to adopt a particular posture in a specific position as much as possible for several days after surgery, and to avoid air travel until the gas bubble has been absorbed (intraocular gas expands at altitude). Afterwards patients will notice a gas-fluid interface in their line of vision (an undulating line) that moves downwards over weeks/months.

Postoperative care

• Topical antibiotics and corticosteroids are prescribed postoperatively.

• Occasionally, patients also need cycloplegic drugs and ocular hypotensive drugs.

• Following discharge, patients should report excessive pain, worsening vision or an increasingly red eye to the team. Headaches and nausea should also be reported (this could be rising intraocular pressure).

Complications

Untreated RD
Some retinal breaks and RDs are long-standing problems that are incidentally picked up. These are more likely to be stable but should be monitored and, depending on the site and size, repair carried out on an elective basis. All new problems should be treated, as they may lead to extensive detachment and ultimately, sight loss.

Laser treatment
Complications are uncommon. If these do occur, they may include macular oedema or scarring, choroidal detachment, secondary tear or haemorrhage.

Cryotherapy
There is often an associated transient lid chemosis. Other complications include transient diplopia, vitritis (inflammation of the vitreous) and, rarely, maculopathy.

Complications of surgical treatment¹² :

• Generic complications include infection and haemorrhage, iatrogenic retinal break during the procedure, retinal incarceration (where the retina folds and gets pulled up into the break).

• Poor visual recovery necessitating the need for a further procedure (due to re-detachment of the retina).

• Rarely, a silicone buckle may dislodge or ulcerate through the conjunctiva.

Prognosis^{1 2}

• If untreated, rhegmatogenous RDs almost always lead to loss of vision. Tractional RDs tend to be more slowly progressive and may have long periods of being static. Exudative RDs may fluctuate according to the underlying disease process.

• Surgical success rates vary by the features of the RD at presentation, particularly the pre-operative visual acuity, how long the retina was detached (and how far lifted off) and whether the macula was involved.

• Within months, photoreceptors in a detached retina have severe and irreversible damage caused by the separation from the underlying choroidal vascular supply, and repair yields less visual improvement.

• The retina is successfully reattached in around 80-90% of cases.

• Final visual acuity is at least 20/40 in 75% of patients whose macula was still 'on'⁷ .

• Final visual acuity of at least 20/40 is achieved in only 40% of those with a detached macula: their recovery varies from none to complete depending on age and on duration and elevation of macular detachment.

• It can take several weeks for the vision to improve after surgery (particularly if there is a gas/silicone bubble in situ).

• Treatment of retinal tears or breaks with laser therapy or cryotherapy is 95% effective in preventing progression to RD.

• There is about 10% chance of RD developing in the fellow eye in phakic patients and a 20-36% chance of developing RD in the fellow eye in pseudophakic patients (those who have had the lens replaced - eg, due to cataract).

• About 10% of patients have a recurrence of the original detachment. The rate of successful reattachment is higher if the detachment is repaired before there is macular involvement.

• Follow-up is essential to rule out RD in the other eye and to monitor for signs of proliferative vitreoretinopathy, which may cause a recurrent RD in the first eye¹³ .

• RD surgery fails in 5-10% of patients because of the growth of scar tissue on the retinal surface in the weeks following repair. Sources of fibrosis include blood cells, fibrin, inflammatory cells associated with postoperative healing, and retinal astrocytes and RPE cells that enter the vitreous cavity when a retinal tear forms. Fibrotic tissue may exert sufficient inward traction to cause re-detachment. This condition, known as proliferative vitreoretinopathy, can be surgically corrected in 60-90% of patients, although visual acuity is often poor. Suppression of epiretinal fibrosis with antiproliferative agents is being intensively investigated.

Prevention⁷

• Protective eyewear is recommended when participating in contact sports, especially for patients with moderate or severe myopia.

• A rhegmatogenous RD can be prevented if the retinal break is diagnosed and treated prior to the accumulation of subretinal fluid.

• Patients undergoing cataract surgery must be instructed about the importance of reporting symptoms of retinal tears and detachments.

• The greatest opportunity for prevention exists in the hours to weeks following PVD and retinal tear formation, because there is often a variable interval between retinal break and detachment. PVD leads to retinal tear in 10-15% of cases. Doctors should be alert for significant symptoms. Asymptomatic new retinal breaks lead to detachment in about 5% of cases but symptomatic new retinal breaks progress to detachment in 50% of cases. Symptomatic retinal breaks may be surrounded with laser or cryogenic burns to create a chorioretinal scar that prevents fluid access into the subretinal space. This treatment is over 95% effective in preventing progression of retinal tear to RD.

Dr Mary Lowth is an author or the original author of this leaflet.