Also called laser treatment, photocoagulation is a group of procedures used to slow the progression of an eye condition called diabetic retinopathy. There are two types of photocoagulation:

• Focal photocoagulation is used to treat macular edema, a type of swelling in the center of the retina.
  
  
• Pan-retinal (scatter) photocoagulation (PRP) is used to treat advanced (proliferative) retinopathy.

Both types of photocoagulation are performed by an ophthalmologist. They both rely on a laser (an amplified beam of light) to make tiny burns on the retina, the light-sensitive tissue at the back of the eye that relays information to the brain. These small burns seal the retina’s blood vessels to prohibit further growth (in PRP) and leaking (in macular edema) caused by retinopathy.

Although photocoagulation is the primary treatment for diabetic retinopathy, not all cases require the procedure. Patients should consult their ophthalmologist to determine if this procedure is right for them. Photocoagulation is also used to treat age-related macular degeneration (a condition in which the macula, the part of the retina responsible for fine vision, deteriorates over time).

Photocoagulation is an outpatient procedure, which means that hospitalization is not necessary. Patients should arrange transportation home from their ophthalmologist’s office or outpatient surgery center because vision may be impaired after the procedure. They should also bring sunglasses to protect their eyes from bright light, as the pupils will be dilated with drops.

Some patients may experience some permanent vision loss after photocoagulation, and severe vision loss may occur in rare cases. Bleeding of the eye area may also occur but should resolve over time.

Although photocoagulation is not intended to cure diabetic retinopathy, it is successful in preventing severe vision loss (20/200 or worse) in about 90 percent of cases, according to the Juvenile Diabetes Research Foundation.

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.

Photocoagulation is typically an outpatient procedure, so it will probably take place at an ophthalmologist’s office or an outpatient surgical center. There is no need to stay overnight in a hospital. Patients should arrange for transportation home after photocoagulation because their vision may be too impaired to drive safely. They are also instructed to bring sunglasses to protect their eyes from the sun, as the pupils will be dilated with drops.

Prior to photocoagulation, the patient will be seated in a chair that is similar to the type used for regular eye examinations. Then, anesthetic eye drops will be administered to allow painless placement of a lens on the eye, and additional drops will be administered to widen (dilate) the pupil. In rare cases, patients may require a numbing injection in the region around the eye.

The patient’s chin and forehead will be placed in a slit lamp, which is a special microscope with an attached light that allows the ophthalmologist to clearly view specific portions of the eye. A special lens will be positioned between the patient’s eyelids to prevent blinking and help focus the laser onto the portions of the retina (the light-sensitive tissue at the back of the eye that relays information to the brain) that require treatment.

Ophthalmologists may choose to take fluorescein angiography photographs before any laser treatment to identify the leaking blood vessels and map the locations where the laser should be directed. For these images, a special dye is injected into the arm, which will eventually flow to the blood vessels in the rear of the eye, and photographs are taken with special filters to allow the blood vessels to be seen more clearly.

During photocoagulation, the ophthalmologist sits in front of the patient and uses a foot pedal to direct a powerful laser beam at the spots in the retina that must be treated. The patient then sees a brief flash of light. This process is repeated several times.  

Although the procedure is not typically painful, the patient may experience some stinging or discomfort. The procedure generally lasts less than 30 minutes. If scatter photocoagulation is performed for more advanced stages of diabetic retinopathy, two or more treatments may be required over several weeks.

After photocoagulation, the treated eye may be sore for a few days. Other side effects tend to be mild. Patients may experience several days of blurred vision after focal laser treatment or pan-retinal photocoagulation (PRP). After PRP, side (peripheral) vision can be reduced or lost, and the eyes will generally take longer to adapt to low light. Most patients can resume usual activities within a few days of the procedure.

Rarely, patients may experience bleeding inside the eye that can last for three or four months. This generally stops on its own, although most patients report residual small floaters (tiny specks in vision) that may disappear over a period of months. If eye bleeding does not cease, patients should contact their ophthalmologist, who may recommend vitrectomy (a surgical procedure in which small instruments and a microscope are used to remove blood and scar tissue from the eye). Full recovery from photocoagulation can take up to six months.

In most cases, the primary benefit of photocoagulation is prevention of blindness. Though not a cure for diabetic retinopathy, this procedure has helped many patients delay or diminish the eye damage caused by diabetes.

Because photocoagulation burns part of the retina, many patients will experience some permanent loss of vision, including:

• Mild loss of central vision (after focal laser)
• Reduced or impaired night vision (after pan-retinal)
• Reduced peripheral vision (after pan-retinal)

All surgical procedures carry some risk. There are several rare complications of photocoagulation that may result in severe vision loss, including:

• Vitreous hemorrhage. A condition in which blood leaking from the new blood vessels enters the vitreous humor (the transparent gel that fills the center of the eye between the lens and the retina).
  
  
• Accidental burn of the fovea (a depression located in the central macula that does not house any blood vessels).

It is important to recognize that the vision loss associated with photocoagulation treatments is mild in comparison to the vision loss that can occur if diabetic retinopathy is left untreated.

Preparing questions in advance can help patients have more meaningful discussions with their physicians regarding their conditions. Patients may wish to ask their doctor the following questions about photocoagulation:

1. Is photocoagulation recommended for me because of diabetic retinopathy, macular degeneration or another condition?
   
   
2. Do I have any alternatives to photocoagulation? If so, what are the advantages and disadvantages of photocoagulation compared to other procedures?
   
   
3. Which type of photocoagulation will I undergo focal or pan-retinal?
   
   
4. Who will perform my photocoagulation? What is this doctor’s experience and track record with the procedure?
   
   
5. What is my risk of vision impairment caused by photocoagulation? Am I more likely to lose central, side or night vision? What is my risk of vision loss if I do not have photocoagulation?
   
   
6. When and where will my photocoagulation take place?
   
   
7. Will I also undergo fluorescein angiography or any other tests or procedures?
   
   
8. What type of anesthesia will I receive?
   
   
9. How long will my procedure last?
   
   
10. Will I experience pain afterward? If so, what type of medication or other treatment will I receive?
    
    
11. What steps should I follow afterward? What activity restrictions might I have to observe?
    
    
12. How long will my recovery take?
    
    
13. If I experience bleeding, how long might it last?
    
    
14. Which side effects should be reported to you?
    
    
15. How can I reduce my risk of needing photocoagulation?