The retina is a thin layer of light sensitive neural tissue, which is present inside the posterior part of the eye and converts light rays into the neural signals and sends them to the brain. Therefore, the retina plays a vital role in the visual system.
The retina receives most of its oxygen and nourishments from the vessels in the choroid, a vascular layer that surrounds the retina.When the retina becomes separated from its underlying choroid, the lack of oxygen and nourishments makes the retina stop functioning, thus loss of vision occurs. Furthermore, if these layers remain detached, the retinal tissues gradually die or undergo so-called necrosis which is irreversible and results in a permanent vision loss. And unless the retina is reattached soon, permanent vision loss may result.That is why retinal detachment is a medical emergency.
Retinal holes are usually caused by sudden stretching of parts of the retina.The eyeball is naturally filled by a jelly-like substance called the vitreous.In childhood and youth, the vitreous has a relatively high consistency, such as egg white, and thus do not have much mobility and by putting pressure on retina, keeps it in place and attached to the outer walls of eyeball.But gradually and as we age, the vitreous loses its consistency and becomes loose and more liquid, as a result the amount of its movement increases and its attachment to the retina becomes weaker. When it happens, usually the posterior parts of the vitreous gel detach from the retina; this is called posterior vitreous detachment, a normal consequence of aging which is very common, and eventually occurs in most of the elderly people. Posterior vitreous detachment (PVD) is usually harmless itself and often has no symptoms other than causing floaters(tiny moving shadows around the field of vision). But sometimes, when the vitreous is detaching from the retina, it pulls so hard that it tears the retina.Since the retinal hole is the main reason for the retina detachment, it is necessary for all the people who have recently had floaters to undergo a precise ophthalmic examination so that appropriate medical treatment is performed if there is a retinal tear or a hole.
Retinal detachment actually means the separation of neurosensory retina layers from the pigmented layer of retina (which is responsible for the retina’s nutrition and metabolism). Since this complication, if not treated properly, causes severe visual loss, immediate diagnosis and medical attention are of utmost importance.
There are three different types of retinal detachment:
• The first type which is the most common one is caused by a hole in the retina. The break in the retina allows the vitreous gel to leak under the retina and separate it from the layers beneath it. The fluid motion along with the effects of gravity, head motion and eye movements, intensifies the retina detaching process. That is why this type of retinal detachment can progress rapidly and lead to a complete retinal detachment over time.
• The second type of detachment (tractional retinal detachment)happens when scar tissue or any other abnormal vitreous tissue on the retina's surface contracts and causes the retina to separate from the RPE (layers underneath).This type is often found in people with diabetes.
• The third type of retinal detachment, which is not common, happens due to abnormal discharge or leakage of fluid between the retina and the underlying tissue.This condition is frequently caused by inflammation, bleeding, or abnormal masses in the eye and rarely occurs spontaneously.
Who Is at Risk of Retinal Detachment?
Different factors increase the risk of retinal detachment. The most important of these factors are:
• Age: Spontaneous retinal detachment rarely happens in people under 40 years and usually occurs in people over 50 years;
• Very high levels of nearsightedness:In extremely nearsighted people, the retina is thin and vulnerable thus it is more prone to detaching than normal;
• Previous eye surgery;
• Family history of retinal detachment or previous retinal detachment in the other eye;
• Severe eye or head injury/trauma;
• Disease, inflammation, or intraocular tumor;
Signs and symptoms
Retinal Detachment may cause different signs and symptoms:
• Flashes of light in the field of vision (particularly if parts of the retina are under traction)
• The appearance of many floaters in the visual field which may seem as cobwebs or specks floating about
• Blurred or warped vision – as when a person looks at an object behind a blurry glass
• Feeling a curtain-like shadow over eyes
• Sudden reduced vision
It should be noted that retinal detachment does not cause pain or redness of the eye and does not alter the appearance of the eye in the early stages. So, if you are experiencing any of the above symptoms, you should consult an ophthalmologist as soon as possible.
Diagnosis and Detection of Retinal Detachment
When a patient with the aforementioned symptoms goes to an ophthalmologist, the ophthalmologist identifies the retinal detachment with a retina examination.For this purpose, pupils usually need to be dilated with special drops and the retina should be examined using a special device called ophthalmoscope. The ophthalmologist then will decide on the appropriate treatment method by examining the location, size, and type of retinal detachment.
In rare cases in which, for example due to hemorrhage, retinal examination is not possible with an ophthalmoscope, ocular ultrasound can provide useful information about the extent, location, and sometimes the cause of retinal detachment.
Treatment for Retinal Detachment
Surgery is the only effective treatment for retinal detachment. Retinal detachment does not go away by itself or by taking medications and surgery should be done as soon as possible. Deciding the type of surgery is based on the location, size, type and severity of retinal detachment. The two basic principles for treating retinal detachment include:
1. Closing the holes/tears
2. Bringing the retina closer to the lower layers and interior wall of the eye, therefore allowing the retina to reattach to its own place.
Accordingly, there are various therapeutic methods for treating a detached retina:
This is an effective method for sealing retinal holes, but it cannot treat retinal detachment on its own.In cases where there is a hole in the retina but retinal detachment has not yet occurred, this method can prevent retinal detachment by closing the hole.In this method which is performed under local anesthetics, your ophthalmologist uses a laser (or a cryotherapy stylus) to make small burns around the retinal tear. As a result,the scarring seals the retina to the underlying tissue, helping to prevent liquefied vitreous leakage to posterior parts of the retina. (Laser burns tissue by heating, whereas cryotherapy stylus does the same thing by freezing).
In this procedure, the eye is numbed with local anesthesia, and then the ophthalmologist injects a gas bubble into middle of the eye. The gas bubble extends inside the eye and pushes the retinal tear into place against the back wall of the eye; in addition, by pressing on the edges of the retinal hole causes the perforated closure and prevents fluid leakage to the back of the retina.Since the gas bubble moves upwards in the eye, this method only works when the break is in the upper part of the retina. To prevent gas bubble dislocation,the patient is asked to constantly maintain a certain head position, even while sleeping, for several days. The gas bubble will be gradually absorbed and disappear in 10 days to 2 weeks.The ophthalmologist then burns around the tear in the retina using a freezing probe (cryotherapy stylus) or laser beam to prevent the reopening of the hole.
Scleral buckling surgery
This is the most common retinal detachment surgery. In this method, a buckle (small band of silicone or plastic) is attached to the outside of the eye (sclera) by fine sutures. This band compresses (buckles) the eye inward, like a tight belt, thus reducing the pulling (traction) of the retina and thereby allowing the retina to settle back into its normal position against the back wall of the eye.The ophthalmologist often drains the fluid under the detached retina, so that the retina would reattach to the interior wall of the eye faster. Furthermore, during the operation, the edges of the retinal holes are also closed using laser beam or cryotherapy stylus.
The scleral buckle stays in place permanently and does not need to be removed (unless it creates a particular problem). Buckle is invisible after surgery and does not significantly affect the appearance of the eye, but it may cause nearsightedness due to the pressure which may lead to the deformation of the eyeball.
In the event that simpler methods fail to treat retinal detachment, a more complex surgery called vitrectomy is performed.In cases where there are numerous or very large retinal holes, or a large part of the retina is detached, or intraocular hemorrhage has happened, or the retina is under traction, usually simpler surgical procedures are less effective and it is necessary to perform vitrectomy surgery.
Sometimes heavy liquids (such as Perfluoron) are injected inside the eye to help hold the retina in position, and then they are replaced by saline serum.Also, sometimes, along with saline, an expandable gas bubble is injected into the eye to keep the upper parts of the retina in place.
Sometimes vitrectomy is combined with a scleral buckle so that the outer pressure helps the retina reattachment.
In special cases where the above mentioned methods do not work, after vitrectomy surgery, silicone oil is injected to fill out the eyeball from within and press the retina in its place. The vision is severely disrupted while this silicon oil is present inside the eye. After a few months, when the retina stick in place, another surgery would be performed, the oil would be removed and saline serum would replace it.
After surgery, especially scleral buckle and vitrectomy, the eye is painful and sensitive for several days. Patients usually need to apply antibiotic drops up to one to two weeks and anti-inflammatory drops for a few weeks after surgery. Sometimes other drops (such as low-pressure medications or pupils dilating drops) are also prescribed. If the gas bubble is injected into the eye, the patients should hold their heads straight for 1-2 weeks, during the recovery time they should even sleep half-seated and never lie on his their back. After vitrectomy, the eye may be swollen, red, and sensitive to light for several days. After surgery, patients may wear eye patches and apply medicated eye drops to help healing and prevent infections. It may take several weeks for patients to fully recover.
In general, after retinal surgery, a person should regularly consult an ophthalmologist to control the retinal position and prevent possible complications.
The result of retinal attachment surgery depends on two important factors:
1. Duration of the period when the retina has been detached from its place.
2. The status of central vision (the macula)
Macula or central vision is the central part of the retina, which is responsible for detailed and direct vision. If the macula has not been removed before surgery, the result of the procedure would be relatively good, so that more than 2/3 of the patients will have enough vision to read after the operation, but if the macula has been removed from its place, after the operation the patient will have a poor vision.
The best surgery results happen when the retina attaches to its place again within one to two weeks; in cases where retinal detachment lasts for a long time, after the operation, the patient will not have a satisfactory vision.
Generally speaking, in 90 to 95% of cases, the retina attaches to its place after one or more surgical procedures, but it should be noted that attaching retina back to its anatomical location does not necessarily improve one's vision. As it is told, the post-operation vision depends on the macula status and retinal detachment duration. In general, the smaller the retinal detacment is, the better the surgical outcome is. In the other word, the larger and the closer to the macula the retinal detachment is, the worse the surgical outcome is.
Retinal detachment prevention
Early diagnosis is the key to successful treatment of retinal detachment.Knowing the quality of vision in both eyes is important.It is recommended that all individuals at risk (nearsighted people, diabetic patients, those with a family history of retinal detachment) should check their eyes daily. For this purpose, each eye should be examined individually by closing the other eye and, if any changes to the eyes are detected,consult an ophthalmologist as soon as possible (within a maximum of 24 hours).If you have had any of the following symptoms consult an ophthalmologist within a maximum of 24 hours:
• Feeling a curtain-like shadow over eyes
• Seeing flashes of light
• The appearance of new floaters or a sudden increase in their number
• Seeing cobweb-like objects floating in front of your eye
• Any sudden reduced vision
Early diagnosis is the key to successful treatment of retinal detachment.
Retinal Detachment Brochure