Focal Laser (Argon)
Focal argon laser photocoagulation is a wonderful solitary or adjunct treatment for swelling in the retina due to diabetes, also known as diabetic "macular edema". This treatment may be used alone, or in combination with intra-vitreal injections. Persistent swelling and thickening in the retina compromises photoreceptor function and long-term visual acuity, so the goal is to reduce the retinal thickness to a normal level by any means necessary.
Dr. Kavoussi recommends focal laser for patients who have significant swelling in the retina in a specific location amenable to the laser. The location must be close enough to the center that worsened swelling would threaten the patient's central vision. At the same time, the location must not be too close to the center such that the laser itself would be detrimental.
The perfect example is demonstrated in the images below. On the left, this thickness map of a patient's retina reveals the thickest area highlighted in red on the upper right corner, just outside the central grid marked in blue lines. In the image the right, three months after the focal laser treatment, the swelling has resolved and that red area is now green, indicating the thickness has reduced to a normal level.
The laser procedure is painless and involves a bright light being focused in the eye for a few minutes. This results in blurred vision in the treated eye that lasts for approximately 10 minutes following the procedure and subsequently returns to normal. Patients can drive and resume normal activities following the procedure. The primary risk of the procedure is a small blind spot in the peripheral vision that is typically not noticed by the patient.
The red area at the upper right indicates thickened retina due to diabetic leakage from damage to blood vessels in the retina. Vision is blurred in the thickened area, resulting in a localized blind spot.
Three months after the focal laser treatment, the swelling has resolved and that red area is now green, indicating the thickness has reduced to a normal level.