Basic anatomy
In this article, we will be discussing retinal detachments and will therefore focus only on the back of the eye.
The eye is full of a jelly called the vitreous which plays a role during the foetal development of the eye and then remains there providing turgor to the eye. The posterior edge of the vitreous is called the posterior hyaloid. In young people, the vitreous forms a homogenous, cohesive mass which “sticks” to the retina.
The retina itself is a multi-layered structure made up of photoreceptors (i.e. rods and cones) along with other cells which allow visual information to be carried to a nerve fibre layer in the inner retina. The retina is supported and nourished by an underlying vascular layer called the choroid, itself overlying the sclera.
Pathophysiology
Rhegmatogenous RDs
The vast majority of retinal detachments are of the “rhegmatogenous” type. This is derived from the Greek rhegma meaning tear or break.
As the vitreous detaches, it causes traction on the retina. This traction can stimulate the photoreceptors leading to flashes of light. In most people, the vitreous will eventually detach without causing any issues and the flashes will cease. This may last weeks. However, in a minority of patients, particularly those with risk factors (as below), this may lead to a tear forming in the retina. If there is a blood vessel in the vicinity of the tear, a bleed may develop, leading to the patient seeing dark “clouds” or spider webs.
From the tear, fluid can enter under the retina causing a “blister” or “tear with sub-retinal fluid” and eventually a detachment.
Almost all tears are located in the retinal periphery, especially supero-temporally i.e. many detachments will start as a shadow infero-nasally (in the eye =, everything is reversed!). Some peripheral tears may be difficult to see, especially if there is an overlying haemorrhage.
Tractional RDs
Most cases of tractional retinal detachment are secondary to proliferative diabetic retinopathy and are caused by tractional bands of fibrosis lifting the retina. These can be observed if they do not threaten the fovea. When treatment is required, it is generally as a vitrectomy with “delamination” i.e. surgical debridement of the scar tissue and tractional bands.
Exudative RDs
These consist of a build-up of exudative fluid underneath the retina caused by underlying disease (choroidal tumours, inflammation): treatment is aimed at the underlying process
Risk factors (for Rhegmatogeous RD)
– Advancing age > 40 years old
– Gender M>F
– Myopia (near-sightedness)
-Previous intraocular surgery
-Direct trauma to the eye
-Contralateral eye retinal detachment
-Family history of retinal detachment
(3)
Symptoms
Sudden increase in floaters and flashing lights
Peripheral shadow coming across the field of vision
When macula detaches, there will be painless sudden loss of central vision (1)
Examination
In the emergency department:
-Visual acuity test using Snellen Chart
-Pupillary examination for (Relative Afferent Pupillary Defect) RAPD
-Visual field testing (can be confrontational)
-Intra-ocular pressure (will often be reduced)
– Possible loss of red reflex
– If a slit lamp is available, note that the anterior 1/3 of the vitreous cavity can be directly visualised without the need for a condensing lens: this can show signs suggestive of a tear including suspended brown retinal pigment (Tobacco dust or Schaffer’s sign)
Note: if the macula remains attached and the detachment is peripheral, patients may remain asymptomatic
Ophthalmological test performed within the department will include:
-Slit lamp assessment using condensing lenses +/- indentation and contact lens assessment, to visualise the fundus and peripheral retina
-Retinal imaging including Optos and Optical Coherence Tomography (OCT), to determine whether the macula is involved.
– B scan (ultrasound of the eye), for visualisation of the retina when there is a poor view (i.e due to haemorrhage/ dense cataract)
Differentials
Based on symptoms alone: any cause of painless visual loss
Based on fundoscopic appearance:
– Retinoschisis:
This consists of a splitting between the layers of the retina itself and is in most cases asymptomatic and picked up during a routine visit at the optician. This relatively common condition can mimic a RD but the area of raised retina is usually more translucent and smooth, without the rugae typical of a RD. Furthermore, it is usually present infero-temporally and is more common in hyperopes (unlike RDs who occur most commonly in myopes). Retinoschisis only very rarely causes a threat to vision and can be monitored in the community.
-Choroidal mass: solid mass associated with sub-retinal fluid
(6)
Management
Exclude GCA as a cause of unilateral visual loss – this needs to be treated as soon as possible, mainly to prevent contralateral involvement
Depending on levels of local expertise, the patient should be referred either to a community optometrist or to the local ophthalmology departments. This can usually be done in hours
Keep the patient NBM in case a GA is required
If the location of the retinal detachment is known the patient should be asked to posture to help reduce subretinal fluid (tilt the head towards the detachment to prevent further progression)
Treatment
Retinal detachments may be treated with a variety of surgical techniques, which aim is to close any retinal tears or hole, reduce vitreous traction and reattach the retina to provide permanent adhesion between the retina and retinal pigment epithelium.
Vitrectomy
Removal of the vitreous to relieve traction and then filling the eye with a gas or oil bubble which acts by 1) preventing re-detachment via the high surface tension between gas and fluid allowing the break to seal 2) holds the retina in place via the buoyancy of the gas
Note: due to the fact gases expand with altitude, patients will not be able to fly until the gas has resorbed, which can vary considerably according to the type of gas used (from a few days for air to 8 weeks for C3F8). This will not be an issue if oil is used, though this will require another operation to be removed and gain full visual potential. Laser/cryotherapy is applied to seal the break intra-operatively.
Note: vitrectomy is associated with a very rapid post-operative progression/development of a cataract which will then necessitate surgery. This may have profound implications in young patients who still can accommodate.
Scleral buckle
Placing a silicone “buckle” on the sclera over the retinal breaks. This indents the eye walls to encourage re-attachment. Buckling has largely been superseded by vitrectomy for most detachments. However, it remains the treatment of choice in some specific cases including retinal dialysis detachment (a type of detachment where the vitreous remains attached to the free edge of the retina), inferior detachments, or detachments in young, phakic patients (unlike vitrectomy, the chance of developing a post-operative cataract is very low).
Pneumatic retinopexy
Small expansile gas bubble injected into vitreous cavity. Strict head positioning is instructed for the bubble to be positioned against retinal break, allowing the retinal pigment epithelium to reattach retina. Laser is applied to seal the break. This technique can be performed in clinic unlike a vitrectomy/buckling and is far less invasive. Unfortunately, the success rate is generally lower than for the vitrectomy/buckling and it can only used in selected patients (breaks restricted to the 8 superior clock hours, breaks within 1 clock hour, no glaucoma, clear retinal view…).
(7)
Summary
–Sudden increase in floaters and flashing light or sudden painless loss of vision – SUSPECT a retinal detachment or tear
– Based on local expertise levels, refer to an optometrist or to the local ophthalmology department for further assessment. This can be done in hours.
-Commonest treatments are vitrectomy or scleral buckle
– Prognosis will depend on whether the macula remains attached and on the durations of detachment. Particularly in cases where the macula remains attached, central vision may be preserved post-operatively
References
1. Yorston D. Emergency management: retinal detachment. Community Eye Health. 2018;31(103):63.
2. John F. Salmon. Kanski’s Clinical Ophthalmology: A systematic Approach . Ninth Edition. 2020. 655–687 p.
3. Shahid A, Iqbal K, Iqbal SM, Ghaffar Z, Tariq M, Jehanzeb Tahir M, et al. Risk Factors Associated With Rhegmatogenous Retinal Detachment. Cureus. 2022 Mar;14(3):e23201.
4. Mortensen Z, Coussa R, Folk J, Boldt C, Troyer J. EyeRounds.Org, The University of Iowa. Rhegmatogenous retinal detachment .
5. Larson T, Starkweather A. Rhegmatogenous Retinal Detachment .
6. Feldman B, Phelps P, Miller A, Barash A, Murchison A, Justin G, et al. Retina Detachment . 2023.
7. NICE: Management of suspected retinal detachment. 2019.
Written by Dr. Lu Jing Tan (FY2), Edited by Dr. Matthew Mo (ST1, Ophthalmology), Edited and checked by Dr. Guillaume Mignot (ST3, Ophthalmology)
1 thought on “Retinal Detachment”
A very interesting read. Very informative !