Understanding The Retina
Light enters the eye and is focused on the retina by the lens. The retina produces a picture which is then sent to the optic nerve which transports the picture to the brain. If the retina is damaged or not in its correct position, a clear picture cannot be produced.
The Retina is basically made up of two layers. There is an inner layer of ‘seeing cells’ called rods and cones. These cells react to light and send electrical signals down tiny nerve fibres (which collect into the optic nerve) to the brain. The outer layer – the retinal pigment epithelium – is a layer of cells behind the rods and cones. These cells help to nourish and support the rods and cones.
- The cone cells (‘cones’) deal with colour vision and sharp detail.
- The rod cells (‘rods’) enable you to see shades of grey and appreciate movement.
The Macula is a small but vital area of the retina at the back of your eye. It is about 5 mm in diameter. The very centre of the macula is called the fovea. The macula is the part of the retina that is the most densely packed with ‘seeing cells’ – especially cones. The macula is responsible for your focused (central) vision. The rest of the retina is responsible for your side (peripheral) vision.
The choroid is a layer of tissue behind the retina, which contains many tiny blood vessels. These help to take oxygen and nutrients to the retina.
Bruch’s membrane is a thin membrane which helps to form a barrier between the choroid and the delicate retina.
The sclera is the outer thick white layer of the eye.
What Is Retinal Detachment And What Causes It?
Retinal detachment (RD) occurs when the inner layer of rods and cones is separated from the retinal pigment epithelium (RPE). This can happen in three different ways:
Rhegmatogenous Retinal Detachment
In this type of RD a hole or break develops in the retina. (The Greek word ‘rhegma’ means ‘a break’.) This can allow fluid from the jelly-like centre of the eye (the vitreous humour) to flow in between the rods and cones of the retina and the RPE. This causes these two layers to separate (detach). This is the most common type of RD.
Note: a break in the retina is quite common, especially in older people. Most retinal breaks do not progress to full-blown RDs, but some do.
Retinal breaks, and therefore the risk of RD, is more likely with the following:
- Near-sightedness (myopia). The greater the myopia, the greater the risk.
- Cataract removal. A cataract is clouding of the lens of your eye. The risk is greatest if the lens is not replaced when the cataract is removed.
- Injury (trauma) to the eye. This is a more common cause in young people.
- Certain sports, especially boxing, bungee jumping and other contact sports, increase the risk of RD.
- Previous RD. Having had RD in one eye increases the risk of RD in the other eye.
- Race. For example, RD is more common in Jews and is quite uncommon in black people.
- People with Marfan’s syndrome.
- Older age. Most cases of RD occur in people over the age of 40. With age, the vitreous shrinks, which causes a vitreous detachment. This is very common in older people and may increase the risk of a retinal tear and therefore RD. However, RD is becoming increasingly common in children, due to sports and leisure activities such as paintball.
Traction Retinal Detachment
Inflammation can cause scar tissue (fibrous tissue) to form on the surface of the rods and cones. This fibrous tissue is attached to the vitreous humour and can pull on the rods and cones, causing them to separate from the RPE. This can occur in various conditions. For example, as a complication of diabetic eye disease and as a complication of other uncommon eye diseases.
Exudative Retinal Detachment
In this type of RD, fluid seeps out of the blood vessels in the retina into the space between the retina and the RPE. This can occur as an uncommon complication of various conditions. For example, very high blood pressure, inflammation of small blood vessels (vasculitis), certain cancers and certain rare blood vessel disorders.
What Are The Symptoms Of Retinal Detachment?
Possible symptoms include:
- Flashing lights. Initially, you may notice flashing lights in your vision. This is noticed in 6 out of 10 people with a RD and is most obvious in dim lighting and in your peripheral or side vision.
- Floaters. These typically appear as one or more black moving dots in your vision. Sometimes they appear like cobwebs or curved/circular shapes. The presence of floaters does not necessarily mean that you have RD, as floaters are common and are often not significant. However, the type of floater you experience helps to determine if it is serious or not. As a general rule, report any new floaters to your doctor or optometrist. In particular, if you have any new floaters in addition to the sensation of flashing lights then see your doctor urgently.
- Vision loss. You may notice shadowing in your peripheral (side) vision, cloudy vision or loss of vision like a curtain coming over your eye.
- No symptoms. Sometimes, RD or tear in the retina is detected on routine eye checks.
It is very important to see your doctor or optician immediately if you have any of these symptoms. If it is RD, the quicker it is treated, the better the outcome.
Are There Any Complications?
If RD is not treated promptly, it can lead to blindness or significant loss of vision.
How Is Retinal Detachment Diagnosed?
RD is diagnosed by an eye specialist using a special lamp to look into the back of your eye. The specialist can also check your vision. If your GP suspects RD from your symptoms or their examination, you should be referred immediately to an eye specialist who can confirm the diagnosis and arrange treatment. The specialist will need to put some drops in your eye to open wide (dilate) your pupil so they can see the retina properly. These drops will cause a temporary blurring of your vision which wears off over a few hours.
There are usually no other tests required to diagnose RD unless the doctor cannot see into your eye properly. For example, if you have a clouding of the lens in your eye (a cataract). In this case, an ultrasound scan of your eye may be done.
Treatment is usually needed urgently. The sooner RD is treated, the better the outcome. In particular, if possible it is best to fix an RD before it extends to affect the macula – the most important seeing part of the retina.
The aim is to get the retina and the RPE to stick back together again. Also, to fix any break in the retina so as to prevent any fluid leaking back underneath the retina again. There are various procedures that can be used to achieve these aims. More than one procedure may be used for the same person, depending on circumstances. The procedure or procedures that are done depend on the size, exact site, duration, severity and type of RD.
The procedures that may be considered include the following.
Treatment Of Retinal Breaks With A Laser Or By Freezing
Most RDs are caused by a break in the retina (described earlier). A retinal break can be fixed with a fine laser or by freezing (cryotherapy) of the break if no fluid has started to seep under the tear. This is done in a hospital clinic using local anaesthetic drops.. This causes a tiny amount of scar tissue to form which seals the break. In effect, it is like ‘welding’ the break back together. This then prevents the RD from progressing further.
This is an operation done under general or local anaesthesia. A small piece of silicone or plastic is stitched next to the outer wall of the eye (the sclera) over the site of the retinal tear. This pushes the sclera (and therefore the RPE) inwards against the detached segment of retina. This procedure is called scleral buckling because the sclera is buckled (pushed inwards) by the small piece of silicone. In some cases a band of silicone may be placed all around the outside of the eye, like a belt.
During the operation, some of the fluid that has built up behind the retina may be drained away. This can help the detached part of the retina to attach better against the RPE. However, if the fluid is not drained away at the time of the operation, it will gradually get absorbed back into the bloodstream.
Once the silicone or plastic buckle is in place, a gas bubble may be injected into the vitreous cavity. This helps to keep the retina flat up against the RPE to help the retina become permanently re-attached. The gas bubble gradually disperses over a few weeks.
The silicone buckle is usually left on the eye permanently. Someone looking at you cannot see the buckle, as it is stitched to the sclera somewhere towards the back of the eye.
Scleral buckling may be done in addition to laser or freezing treatment to fix a retinal break.
This may be done under local anaesthetic. The eye specialist injects a gas bubble into the vitreous cavity of the eye. The bubble pushes the detached part of the retina flat back up against the RPE. This then allows the retina and the RPE to re-attach permanently.
The gas bubble gradually disperses and goes over a few weeks.
For this treatment to work, you must keep your head in a set position for most of the time for a few weeks. This is because the bubble ‘rises’. Some people find this too uncomfortable and so pneumatic retinopexy may not be suitable for everyone.
This head positioning can be tedious and hard work for the few weeks that it may be needed until the retina is firmly attached back to its proper place.
Pneumatic retinopexy may be done in addition to laser or freezing treatment to fix a retinal break.
This is done under general or local anaesthesia. The gel-like substance called the vitreous humour is removed. The space left is then filled with a gas (or sometimes liquid) which pushes the retina back into place. The gas eventually disperses but is replaced by natural body fluid made in the eye.
A scleral buckle may be applied at the same time as a vitrectomy is performed.
After any treatment, if you experience significant pain or deterioration in your vision, you must inform your doctor immediately.
What Is The Outlook (Prognosis)?
This depends on several factors:
- The length of time that the retina has been detached
- The cause of the RD
- The amount of the retina that is involved
- Whether the macula is involved
If the RD does not involve the macula and is treated promptly, then a good recovery with restoration of most of your vision is expected. It may take some weeks for vision to improve and glasses may be required permanently to aid vision.
Unfortunately, if the macula has detached, the prognosis is not good and long-term reduced vision or even blindness in the affected eye is expected.
It is possible for RD to recur. Also, having had it in one eye increases the risk of it happening in the other eye.
Our Appointments Team have a dedicated and caring approach to finding you the earliest appointment possible with the best specialist.
If you do not have a GP, then we have an in-house private GP practice that you can use. Alternatively we can suggest the most appropriate course of action for you to take, given your location and individual circumstance.
If you have medical insurance (e.g. Bupa, Axa PPP, Norwich Union), you will need to contact your insurer to get authorisation for any treatment and, in most cases, you will require a referral letter from your GP.