Angeles Vision Clinic
The retina is the neurosensory tissue that lines the back inside wall of the eye, just like wall paper on a sheetrock wall. Just like the film in a camera, the retina transfers the light coming into our eye into vision. The center of the retina is called the macula and is the only part capable of fine detailed vision, i.e. reading vision, recognizing faces, etc. The remainder of the retina , the peripheral retina, is for side vision. The retina outside the center of the macula, which makes up more than 95% of the retina, is not capable of the fine detailed vision.
When the retina detaches, it separates from the back wall of the eye and is removed from its blood supply and source of nutrition. The retina will degenerate and lose its ability to function if it remains detached. Central vision will be lost if the macula remains detached. The causes of retinal detachment can be divided into three main categories:
RHEGMATOGENOUS RETINAL DETACHMENTS
This is the most common type of retinal detachment and usually occurs when the vitreous separates from the back wall of the eye. The vitreous is the clear gel that fills the central cavity of the eye. The formed vitreous gel liquefies with age and eventually falls away or separates from the retina. This is called a posterior vitreous detachment (PVD) and is a normal event occurring in most people sometime between 40-70 years of age. As the gel separates and falls away from the center of the retina, one will often see floaters. These appear as dots, spots, or curly lines that appear suspended in front of you and move with your eye. People often think these floaters are flying bugs. Flashes of light are also a common symptom of a PVD. These are due to pulling on the retina as the gel separates. This pulling stimulates the retina, resulting in a flash of light. If a retinal blood vessel is broken from the pulling, a vitreous hemorrhage can occur. A small amount of blood may be seen by the patient as a shower of spots. Larger hemorrhages can cause large dark blobs in the visual field or a overall decrease in vision. If the gel is abnormally adherent to the retina or the retina is weak in a certain area, a retinal tear can occur as the gel separates and pulls away from the retina. Fortunately, the great majority of PVDs do not cause a retinal tear. Sometimes, a PVD can occur without any symptoms, and sometimes, there can be lots of annoying symptoms without any retinal breaks.
A retinal detachment can occur once there is a retinal break. The liquid vitreous passes through the break and goes under the retina. The retina will then start to detach from the underlying tissue. Since most tears occur in the peripheral retina, the detachment will first cause loss of a portion of the side vision. This can be seen as a curtain or dark shadow involving the peripheral vision. As the detachment extends towards the macula, the shadow will also enlarge. Central vision will be lost if the macula detaches. Without surgical repair, most rhegmatogenous detachments will eventually involve the entire retina and all vision will be lost.
Cross-section of eye with retinal detachment
(flashes, floaters, shower of spots). A thorough dilated examination with
indirect ophthalmoscopy, contact lens exam and scleral depression is required to
find retinal breaks and other areas at risk for detaching. If no breaks are
found at the initial exam, it is important to be re-examined within 1-2 weeks or
sooner if new symptoms develop. The vitreous can continue to separate and pull
on the retina for several weeks or longer and the retina can develop a tear
during this time. Even if a tear is discovered and treated, follow-up
examination from your eye care
provider is necessary to be sure the laser reaction is working and that no
additional tears have developed. Not all retinal breaks need to be treated .
Many people have round or atrophic holes in their retina that are discovered on
routine examination and, usually, these do not need to be treated. In general ,
however, if a retinal break is discovered in association with new symptoms of a
PVD or there are other high risk factors for a retinal detachment (family
history, very near sighted, detachment in other eye, history eye trauma, prior
cataract surgery, etc…) treatment is indicated. Treatment of retinal breaks
with the laser or cryoprobe is very successful and retinal detachment can
usually be avoided if the retinal breaks are identified and treated.
Unfortunately, sometimes a retinal tear will lead almost immediately to
detachment or there may not be any symptoms of a PVD, retinal tear or
detachment. For these and other reasons, many people will have a retinal
detachment when first examined and will almost always require some sort of
REPAIR OF RHEGMATOGENOUS RETINAL DETACHMENT
Fortunately, over 90% of retinal detachments can be repaired with a single procedure. Currently, there are 3 different surgical approaches to repairing a detachment: scleral buckle procedure, vitrectomy and pneumatic retinopexy.
Vitrectomy: Usually referred to as a trans pars plana vitrectomy (TPPV), this procedure was first used ~ 20 years ago and has been continuously refined and improved since then. It is most commonly used for traction retinal detachments from diabetes but is also used for rhegmatogenous detachments especially if they are associated with vitreous traction or vitreous hemorrhage. The procedure involves making small incisions into the wall of the eye to allow the introduction of instruments into the vitreous cavity (the middle of the eyeball). The first part of the procedure usually is the removal of the vitreous using a vitreous cutter. Then, depending on the type and cause of the detachment, a variety of instruments (scissors, forceps, pics, lasers, etc…) and techniques (excision of tractional bands, air-fluid exchange, silicone oil fill, etc…) are used to reattach the retina. A TPPV can also usually be done as same day surgery and with local anesthesia. It is sometimes important to maintain a specific head position after surgery to keep the retina attached. More information regarding vitrectomy surgery can be found on the Vitrectomy page.
Pneumatic retinopexy: Over the past 10 years, this has become a popular way to repair a straight-forward rhegmatogenous retinal detachment, especially if there is a single break located in the superior portion of the retina. This procedure involves injecting a gas bubble into the middle part of the eye (vitreous cavity). It is then critical to position oneself so that the gas bubble covers the retinal break. If the break can be covered by the bubble, the subretinal fluid will usually resolve within 1-2 days. The retinal tear is either treated with cryopexy before the bubble is injected or with laser after the retina has flattened. The main advantages of this approach are that it can be done in the office, thus avoiding hospitalization and that it avoids some of the complications of scleral buckling surgery, although it has its own set of complications. The main disadvantages are the requirement for precise head positioning for up to 7-10 days following the procedure and a slightly lower initial success rate as compared to a scleral buckle. If the retina is not reattached by a pneumatic retinopexy procedure, a scleral buckle and/or TPPV can be done at that point.
Approximately 90% of rhegmatogenous detachments can be initially repaired with one or a combination of these procedures. Sometimes, a scleral buckle is combined with a TPPV. If the retina does not reattach or detaches again after initial reattachment, it is usually due to the development of scar tissue on the surface of the retina and tractional forces within the vitreous cavity. If this happens following a scleral buckle procedure, it is often necessary to do a TPPV to repair the detachment. Sometimes, an intraocular gas bubble can be injected and the retina reattached following positioning. If a TPPV was done initially, it is often necessary to go back and do another TPPV to remove the new scar tissue and/or perform a scleral buckle. If a pneumatic retinopexy was the initial procedure, another pneumatic can be done or a scleral buckle or TPPV can be performed. As one can tell, there is no set way to repair a detachment and all the available procedures can be used in different combinations and sequences depending on the specific situation.
The visual prognosis depends mainly on the pre-existing status of the retina before it detached. If the macula has not detached, the pre-existing vision will usually be retained following successful repair. However if the macula is detached and central vision is impaired by the detachment, there may be permanent loss of central vision even if the retina is successfully repaired. The longer the macula is detached, the more likely there will be loss of vision due to irreversible damage to the photoreceptor cells. In general, if the center of the macula is detached for more than 4-5 days, there will be significant loss of central vision following surgical reattachment.
Please note that much of the above content was provided compliments of: Vitreous-Retina-Macular Consultants New York