Photocoagulation is a laser treatment used to delay the progression of diabetic retinopathy. This eye disease occurs most often in people who have had diabetes for many years and have poor control of glucose (blood sugar).

Diabetic retinopathy can affect individuals with type 1 diabetes, type 2 diabetes or other forms of diabetes, such as maturity-onset diabetes of the young (MODY). It can even develop in people with prediabetes, according to recent findings from the Diabetes Prevention Program.

The type of photocoagulation used to treat diabetic retinopathy depends on the type of problem caused by the disease. Diabetic retinopathy occurs in two phases:

• Nonproliferative retinopathy. Occurs when the small blood vessels (capillaries) in the retina (the light-sensitive tissue at the back of the eye that relays information to the brain) begin to leak fluid, resulting in vision loss. This condition does not necessarily progress to proliferative retinopathy.
  
  
• Proliferative retinopathy. Defined by the development of new, abnormal blood vessels in the retina. These vessels can hemorrhage (bleed) and lead to blurry vision. This condition is called macular edema.

Photocoagulation is the primary surgical treatment for diabetic retinopathy. Mild to moderate nonproliferative retinopathy is usually first treated by maintaining control over blood glucose levels.

If the retinopathy continues to worsen, photocoagulation may be performed. It can also be used to treat age-related macular degeneration (a condition in which the part of the retina called the macula deteriorates over time).

There are two types of photocoagulation. The first type is called focal photocoagulation. This procedure is usually effective in treating patients with macular edema. During focal photocoagulation, the ophthalmologist aims or “focuses” the special laser directly at the leaking blood vessels in the retina and makes a limited number of burns to seal them.

The second procedure is called scatter or panretinal photocoagulation. It is used to treat proliferative retinopathy and its associated conditions, including:

• Vitreous hemorrhage. A condition in which blood leaking from the new blood vessels enters the vitreous humor (the transparent mass of gel that fills the center of the eye between the lens and the retina), causing visual impairment.
  
  
• Traction retinal detachment. A condition in which the new capillaries form scar tissue that shrinks and pulls the retina away from the eye’s back wall, impairing vision.
  
  
• Neovascular glaucoma. A condition in which abnormal new blood vessels grow on the iris (the colored part of the eye, which regulates light entering the eye) and raise the pressure in the eye, destroying the ability to see.

When scatter photocoagulation is performed, the ophthalmologist “scatters” hundreds of tiny burns across the peripheral retina in a polka-dot pattern. This delays the growth of any abnormal blood vessels that have developed in the macula. This procedure typically occurs over the course of two or more visits. Scatter photocoagulation is most effective in the early stages of diabetic retinopathy, before bleeding or retinal detachment has progressed beyond laser repair.

If performed in the early stages of diabetic retinopathy, photocoagulation can prevent severe vision loss in about 90 percent of cases, according to the Juvenile Diabetes Research Foundation. It is important to note that photocoagulation is performed in an effort to prevent or delay the progression of diabetic retinopathy – it is not intended to cure the condition. Additionally, not all patients with diabetic retinopathy are good candidates for photocoagulation. Patients should consult their ophthalmologist to determine if this procedure is right for them.