Laser photocoagulation uses the heat from a laser to seal or destroy abnormal, leaking blood vessels in the retina. One of two approaches may be used when treating diabetic retinopathy:

• Focal photocoagulation. Focal treatment is used to seal specific leaking blood vessels in a small area of the retina, usually near the macula. The ophthalmologist identifies individual blood vessels for treatment and makes a limited number of laser burns to seal them off.
• Scatter (pan-retinal) photocoagulation. Scatter treatment is used to slow the growth of new abnormal blood vessels that have developed over a wide area of the retina. The ophthalmologist may make hundreds of laser burns on the retina to stop the blood vessels from growing. The person may need two or more treatment sessions.

Laser photocoagulation is not usually painful. The injection of anesthetic may be uncomfortable. And then you may feel a slight stinging sensation or see brief flashes of light when the laser is applied to your eye.

What To Expect After Treatment

Laser photocoagulation is usually performed as an outpatient procedure using a local or topical anesthetic that affects only the eye. You do not have to stay overnight in a hospital.

You will need someone to drive you home from the doctor's office or clinic after the procedure. Eyedrops are used to widen (dilate) your pupils before the procedure, and your eyes will remain dilated for several hours afterward. Wear sunglasses to keep bright light out of your eyes while they are still dilated.

Your vision may be blurry and your eye may hurt a little for a day or two after the treatment.

Be sure to keep all follow-up appointments with your doctor and report any changes in vision that you experience. Follow-up treatment can make a big difference in maintaining your vision for the long term. ¹

Why It Is Done

Laser photocoagulation is done to reduce the risk of vision loss caused by diabetic retinopathy. It is most often used to stabilize vision and prevent future vision loss rather than to improve vision loss that has already occurred. (Sometimes focal photocoagulation for macular edema caused by nonproliferative retinopathy can help restore lost vision.)

Laser photocoagulation may be used to treat and prevent further progression of:

• Macular edema. Focal photocoagulation is usually used in these cases.
• Proliferative retinopathy. Scatter (pan-retinal) photocoagulation is used to treat proliferative retinopathy.

How Well It Works

Laser treatment may not restore vision that has already been lost. But when performed in a timely manner: ²

• Focal photocoagulation, which targets specific blood vessels, is effective in reducing the risk of vision loss in people with macular edema. It lowers the risk of moderate vision loss by 20% in people who have mild to moderate nonproliferative diabetic retinopathy.
• Scatter (pan-retinal) photocoagulation, which treats a wide area of the retina, reduces the risk for severe vision loss by 50% to 60% over 6 years in people with a high risk of vision loss. It reduces the risk of serious bleeding and progression of severe proliferative retinopathy and the need for surgery (vitrectomy) by 50% in people with type 2 diabetes and people age 40 and older with type 1 diabetes who already have severe nonproliferative or mild proliferative retinopathy. Studies suggest that up to 90% of cases of legal blindness caused by proliferative retinopathy could be prevented by prompt scatter photocoagulation.

Risks

Laser photocoagulation burns and destroys part of the retina and often results in some permanent vision loss. This is usually unavoidable. Treatment may cause mild loss of central vision, reduced night vision, and decreased ability to focus. Some people may lose some of their side (peripheral) vision. But the vision loss caused by laser treatment is mild compared with the vision loss that may be caused by untreated retinopathy.

Rare complications of laser photocoagulation may cause severe vision loss. These include:

• Bleeding in the eye (vitreous hemorrhage).
• Traction retinal detachment.
• Accidental laser burn of the fovea (a depression in the central macula that contains no blood vessels), resulting in severe central vision loss.

What To Think About

The biggest drawback to laser photocoagulation is that the laser damages some of the light-sensitive nerve cells in the retina and macula. This often results in some vision loss.

But the immediate vision loss caused by laser treatment must be measured against the more severe vision loss that could result from untreated retinopathy. For people with diabetic retinopathy, laser photocoagulation is very likely to help prevent more severe vision loss over time.

Diabetes experts agree that early detection and treatment of retinopathy can prevent many, or even most, cases of severe vision loss and blindness in people with diabetes.

It is also important to keep your blood sugar levels low after laser treatment. Even if your eyes are better, diabetic retinopathy will keep getting worse over time if your blood sugar levels rise again.

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Citations

1. Chew EY, et al. (2003). The long-term effects of laser photocoagulation treatment in patients with diabetic retinopathy: The early treatment diabetic retinopathy follow-up study. Ophthalmology 110(9): 1683–1689.

2. Begg IS, et al. (2001). Eye disease. In HC Gerstein, RB Haynes, eds., Evidence-Based Diabetes Care, pp. 396–428. Hamilton, ON: BC Decker.