Questions and Answers About Laser Surgery and Diabetes

What is the purpose of Laser surgery?
In nonproliferative diabetic retinopathy (NPDR), leaking blood vessels can cause the retina to become wet and swollen, resulting in macular edema and loss of vision.  The goal of laser surgery in NPDR is to stop the leakage from these vessels and to prevent further visual loss.
In proliferative diabetic retinopathy (PDR), neovascularization can cause severe visual loss by bleeding into the eye (called vitreous hemorrhage) and by developing scar tissue that can pull on the retina and cause traction retinal detachment.  The goal of laser surgery in PDR is to stop the growth of these vessels and to prevent vitreous hemorrhage, traction retinal detachment, and severe visual loss.

Will I have to go to the hospital?
Laser surgery is usually done in the doctor's office or in the hospital as outpatient surgery.  You may eat before the laser surgery.  After the surgery, you will be able to go home and resume your normal activities without special restrictions.

Is the laser surgery safe?
In most cases, no complications occur but, as with all surgery, there are some risks.  There is a remote chance that the laser beam might not be aimed properly and that healthy retina might be destroyed and vision lost.  Laser may also cause bleeding or an unusually large scar.  Fortunately, these complications are rare.
For PDR, most patients who  receive panretinal laser photocoagulation have already lost some night vision.  It is common for the patient with PDR who has had panretinal laser photocoagulation in each eye to have difficulty with night driving.  This is not always the case, but it is frequent.  Also, after panretinal laser photocoagulation, the peripheral, or side, vision is often not as good as before surgery.  In a few patients, the pupil remains dilated for many months, and in some very rate cases, forever.  Most patients have some degree of blurring of central vision immediately following panretinal laser photocoagulation.  In a few patients, this blurring may be permanent.  Usually this blurring is not great, but on rare occasions it is.  Rarely, there is so much swelling inside the eye after laser surgery that the pressure within the eye can become dangerously high.  If the pressure becomes very high, the patient will experience a great deal of pain and should promptly call the treating doctor.

In NPDR, will the leaking blood vessels be permanently closed by laser, and in PDR, will the abnormal new retinal blood vessels be permanently destroyed by panretinal laser photoagulation?
In most cases of NPDR that have been treated with laser, the leaking blood vessels remain closed.  But because the diabetes continues, it is common for the leakage to begin in new areas.  If laser surgery is indicated, however, the chances are better that the treated blood vessels will stop leaking than if no laser surgery is done.
In most cases of PDR, the growth of neovascularization is stopped permanently after laser surgery, and most of the neovascularization that was present becomes inactive or disappears.  Nevertheless, it is quite possible that the neovascularization will not disappear totally.  It may even grow back to some extent after surgery, though this is not common.  When only a small amount of neovascularization remains after panretinal laser photocoagulation, it is generally not a problem, and further laser is frequently not necessary.  If the amount of neovascularization remaining is great enough, however, more laser may be necessary.  In some patients who have had panretinal laser photocoagulation, small vitreous hemorrhages will occur from time to time.  Generally, these are quite mild.  If a patient sits up during the day and keeps the head somewhat elevated during sleep, the blood in the eye will settle and vision returns to normal within a day or two.  Such hemorrhages are called "nuisance" or "tolerable" hemorrhages, and further laser surgery is not usually necessary.

Does the laser surgery cause any pain?
For NPDR, laser surgery is almost always painless, though a few patients do experience some discomfort.  In rare instances, the eye must be anesthetized to keep it steady for the laser surgery.  An anesthetic is injected through the lower eyelid and behind the eye so that it cannot move and will not feel anything.  After the laser surgery, the eye is patched for the rest of the day.
In PDR, many patients who receive panretinal laser photocoagulation experience some discomfort or pain.  In those patients where the pain is great, it is best to anesthetize the eye.  The anesthetic is injected behind the eye.  After laser surgery, the eye is patched for the rest of the day.  After the anesthetic wears off, the patient may experience discomfort or pain.  Your doctor can advise you as to the need for pain medication.  If the pain is severe, call your doctor promptly as there could be a serious problem.

How long does laser surgery take?
Depending on the extent of the problem, laser surgery for NPDR may take anywhere from a few minutes to one-half hour; for PDR it may take anywhere from fifteen minutes to one hour or more.

Are all forms of laser the same?
The various types of laser differ according to their wavelength (or color).  The lasers used in treating diabetic retinopathy are argon blue-green, argon green-only, krypton-red, and also tunable dye lasers.  Each wavelength or color is absorbed differently by the tissues of the eye.  Your doctor will decide which laser is best for your particular situation.

Are there any aftereffects?
Because of the intense brightness of the laser beam, there is a light-dazzle, or "flashbulb" effect immediately afterwards, and vision may be dark for 10 to 15 minutes.  This is not harmful to the eye.  The eye takes a few hours to recover from this glare.

What will my vision be like immediately after laser?
Following laser surgery for NPDR, vision is often blurred, but it usually improves within a month.  There may be small black areas, or blind spots, where the laser spots were placed, usually just to the side of central vision.  These blind spots, if present, will be permanent but will become less noticeable as time passes.  When grid laser is done, patients may notice a great many spots in all directions from center.
Following panretinal laser photocoagulation for PDR, vision is often blurred, but it usually improves within a month or two.  Side, or peripheral, vision and night vision are likely to be reduced permanently.  In a few patients, central vision is blurred permanently but, generally, this blurriness is not great.

Do I need to avoid any activities after surgery?
After both NPDR and PDR treatments, you may resume normal activities and use of the eyes the same day as laser surgery.

How many treatments will I need?
For NPDR, although we are always hopeful that only one laser surgery will be necessary, the blood vessels may become leaky again, or new leaks may develop, and for many patients, additional laser surgery is necessary.  The need for more than one laser surgery for NPDR is common.
For PDR, one to three laser surgery sessions are all that are usually needed, initially.  But if the neovascularization does not go away, or if more develops, additional laser surgery may be required.

How does one know if the laser surgery has helped?
Several weeks or months after laser surgery, you will return for a follow-up examination and possibly a fluorescein angiogram.  If you had NPDR, the leakage should have stopped by this time.  If you had PDR, the neovascularization should have shrunk.  If this is the case, the laser surgery will be considered to have been temporarily successful.  Your doctor will advise you when to return for follow-up examination.

What if the laser surgery did not work?
In NPDR, if there is still significant leakage and persistent macular edema, additional laser surgery or grid laser may be helpful.  In fact, more than one treatment is usually necessary for NPDR.  For some cases, further laser surgery is not possible, and special visual aids may be recommended (see question #14).
In PDR, if there is more growth of neovascularization, or if the neovascularization has not gone away adequately, additional laser surgery may be necessary.  If, despite adequate laser surgery, a vitreous hemorrhage develops and does not clear, or if scar tissue forms and wrinkles or detaches the retina, vitrectomy can be performed.

Can anything help if central vision is lost in each eye?
Those patients who have lost central or detail vision in both eyes will be referred to a low vision specialist who helps patients learn to use the remaining vision to its fullest.  Low vision specialists can fit magnifying lenses to assist close-up vision and telescopic lenses for seeing at a distance.  There are other visual and mechanical devices including special filters, increased lighting, and special tools for reading that can help patients function better.  Patients will learn about books on tapes, radio programs that read the news, and support groups to help patients cope with the problems of central vision loss so as to live their lives to the fullest, even with reduced vision.

Will using my eyes hurt them?
It is important to know that you cannot hurt your eyes by using them.  There is no way in which using your eyes can do your eyes any harm, whether by reading, watching television, or driving for long periods of time.

Do I need to wear sunglasses?
There has been some research suggesting that increased exposure to sunlight may be associated with some eye problems.  While the connection between exposure to sunlight and damage to the eye has not been proven, it is probably a good idea to use dark sunglasses in bright sunlight, preferably sunglasses designed to filter out especially blue and ultraviolet light.

Is it normal to have trouble adjusting quickly between bright sunlight and dim light?
Many patients who have diabetic retinopathy have difficulty adjusting quickly between bright light and dim light, or shadow.  It may be difficult to adjust when driving from bright sunlight into a dark tunnel, or reading the menu in a dark restaurant when one has just come in and bright sunlight.  This difficulty can be overcome somewhat by using clip-on sunglasses over regular glasses.  These clip-on sunglasses can be slipped off easily when going from light to dark and can then be slipped  back on again when going from dark to light.