"Vitrectomy" refers to the removal of the vitreous gel from the eye. This procedure is performed in a hospital operating room using an operating microscope. There are several retinal disorders for which vitrectomy surgery may be indicated, some of which are listed below.
The vitreous is removed using small instruments inserted through needle-size incisions in the eye wall. Fiber-optic lights are used to see inside the eye, and often to deliver laser treatment when necessary.
Vitrectomy is typically performed under local (injection) anesthesia, with sedation. In other words, the patient is awake during the procedure, but does not feel pain or see the procedure being performed. General anesthesia may be used instead in some cases. It is an outpatient procedure; no hospital stay is required.
Patients go home with a patch on the eye, which is removed in the doctor's office on the day after surgery. There may be several follow-up visits during the first month, and visits less frequently for a few months beyond. Eyedrops are used for a few weeks after the surgery. These typically include steroid drops to minimize inflammation, antibiotic drops to prevent infection, and dilating drops to provide comfort and minimize scarring of the pupil. Drops to lower the pressure in the eye are also sometimes necessary. Patients are usually able to return to normal activity within a few weeks. Most of the healing occurs during the first month, but full visual recovery may take a few months.
At the time of vitrectomy surgery, the eye is often filled with air, or a mixture of air and gas. This may be done to prevent or repair retinal detachment, close a macular hole, or for other reasons. The type of gas used depends on the circumstances. The gas is reabsorbed by the eye over a period of time; air usually lasts about a week, while longer acting gases may take 2 months to be reabsorbed. It is replaced with the clear aqueous fluid which your eye produces at all times.
When the eye is filled with gas, the vision is very poor. Patients can sometimes see better, though, while looking straight downward and holding an object just a couple of inches from the eye. As the gas bubble becomes smaller, the patient will see it shrinking towards the bottom of the field of vision. It may cause glare and double vision, especially when it is about halfway reabsorbed. When the bubble becomes rather small, it tends to break up into a few smaller bubbles before disappearing altogether.
Certain precautions should be observed when there is a gas bubble in the eye. First of all, the patient must maintain the head position recommended by their doctor. In most cases, this means looking straight downward, or lying on one side. Patients should avoid looking upward or lying on their back for any significant period of time, to minimize anterior movement of the bubble, which can accelerate cataract formation, raise intraocular pressure, or damage the cornea. Finally, patients must avoid flying with an air or gas bubble in the eye. The reduced atmospheric pressure causes the gas bubble to expand, which can raise the pressure in the eye to dangerous levels. Your doctor can tell you when it is safe to fly.
Silicone oil is a clear, viscous fluid which is used in some patients instead of a gas bubble. It has some advantages over long-acting gas: quicker visual recovery, no restriction on air travel, less need for head positioning after surgery, and longer duration of effect. Unlike gas, however, silicone oil is not removed from the eye by your body; it must be removed in a second surgery, which is usually very similar to the initial vitrectomy. Certain complications are also more frequently associated with the use of silicone oil.
As with any surgery, vitrectomy has risks. Cataract, retinal detachment, high intraocular pressure, bleeding in the eye, and infection are among the possible complications. Cataract is the most frequent complication of vitrectomy surgery. Many patients develop a significant cataract within the first few years after vitrectomy.
Detaching the vitreous gel from the retinal surface is an important part of macular hole surgery. In addition, there are frequently thin membranes on the retinal surface surrounding the hole which are peeled in order to release traction on the retina and allow the hole to close. Perhaps the most important part of the surgery, however, is filling of the vitreous cavity with a bubble of gas.
This gas bubble must press against the macular hole in order for the hole to close. Since the macula is located at the back of the eye, the eye should be looking downward in order for the bubble to float against it and exert the maximal amount of force. In order for this to occur, the patient must remain in a face-down position after the surgery. For most patients, 2 weeks of face-down postioning is recommended.
The macular hole can be closed successfully in the vast majority of patients. This is usually accompanied by a significant improvement in vision and reduction of distortion. Most patients, however, will not recover all the vision that was lost, and will recognize some limitation.
A macular pucker is caused by a thin membrane of scar-like tissue on the surface of the retina. After the vitreous gel is removed from the eye, small instruments are use to gently peel this tissue and remove it from the eye. Gas or air might be placed in the eye in order to help smooth out the retina and to prevent retinal detachment; many patients with macular pucker also have retinal tears or a history of retinal detachment. If a bubble is used, then positioning after the surgery is necessary, usually just for a few days, but sometimes longer.
Successful peeling of the pucker from the retinal surface is almost always achieved, and this usually leads to visual improvement and reduced distortion. Many patients, however, still recognize some distortion and limitation of the vision.
Vitrectomy for Diabetic Retinopathy
Vitrectomy is sometimes recommended in diabetics for the treatment of macular edema, vitreous hemorrhage, or traction retinal detachment. In some patients, membranes form on the surface of the retina. Traction from these membranes and from the vitreous gel may contribute to macular edema. Removing the vitreous and the membranes may therefore improve macular edema. In more severe cases, the vitreous gel and the membranes on the retinal surface pull very forcefully on the retinal surface, causing elevation of the retina, or traction retinal detachment. Vitrectomy to remove the vitreous and the membranes allows the retina to flatten again. When neovascularization causes vitreous hemorrhage, blood suspended in the vitreous gel obscures the vision. This blood often clears spontaneously, though it may take several months in some cases. If the hemorrhage is significant and does not clear in a reasonable amount of time, then vitrectomy to remove the blood-filled vitreous may be considered. During vitrectomy in diabetics, panretinal photocoagulation laser treatment is often performed using a small fiber-optic inside the eye. Also, gas or air might be placed in the eye in order to help smooth out the retina and to prevent retinal detachment. If a bubble is used, then positioning after the surgery is necessary, often for a couple of weeks.
Vitrectomy for Retinal Detachment
Certain types of retinal detachment are treated with vitrectomy surgery. Examples include detachments with significant bleeding in the eye, detachments associated with cytomegalovirus retinitis or other infections, and detachments with traction from the vitreous gel or membranes on the retinal surface. A scleral buckle is often placed at the same time. Almost always, a gas or air bubble is used to fill the vitreous cavity and keep the retina in position while it heals. If a bubble is used, then positioning after the surgery is necessary, often for a couple of weeks. Laser treatment applied during the surgery helps keep the retina permanently attached.
Vitrectomy may be necessary in certain patients with uveitis in order to obtain a specimen of the vitreous, which can then be evaluated in a laboratory for diagnostic purposes. Vitrectomy can also improve vision by removing inflammatory debris and by improving macular edema. In addition, uveitis is sometimes more easily controlled once the vitreous gel is removed.
Vitrectomy for Macular Degeneration
A small number of patients with choroidal neovascularization due to age-related macular degeneration or other causes may benefit from vitrectomy surgery. Bleeding beneath the retina in such cases can lead to severe visual loss. The blood is sometimes removed at the time of the vitrectomy through a small hole in the retina. A gas or air bubble in the vitreous cavity may also help to displace the blood inferiorly, away from the macula, thus improving central vision. The choroidal neovascular membrane itself may also be removed at the time of vitrectomy through a small hole in the retina. These approaches are referred to as submacular surgery.
Another strategy is referred to as macular translocation. A blood vessel membrane beneath the center of the macula will always cause some degree of visual loss, even when successfully treated with other means. In macular translocation surgery, the retina is detached intentionally, then repositioned in a new location. The blood vessel membrane no longer lies beneath the central macula after surgery, allowing for more significant visual improvement and treatment of the membrane without affecting central vision. The retina can only be moved a small distance, though, and the surgery has a fairly high complication rate. Thus, few patients are good candidates for this surgery, especially with the advent of photodynamic therapy.
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