LASER THERAPY - OVERVIEW

We use green, yellow, and red lasers to treat the retina. These color lasers are all useful for treating leaking blood vessels or tacking down the retina. Green is useful for tacking down the retina. Yellow is useful for sealing leaky blood vessels. Red is useful for treating through blood. Other lasers used in ophthalmology (the eye) but not by retina specialists inlcude YAG laser to open membranes in the eye, excimer laser to shape the cornea, and argon laser for glaucoma. Retina specialists also use photodynamic laser which is a combination laser drug treatment. A drug (visudyne) is injected into an arm vein. Once it reaches the eye, it can be activated with a low energy red laser to seal up abnormal and leaking retinal vessels. It is useful in macular degeneration and also to treat some choroidal tumors and in central serous retinopathy.

During surgery for retinal detachment, once the retina is attached, laser is used to create an adhesion between the retina and the eye wall.  The adhesion formed by the laser spots takes a week or two to mature.  This is like glue that takes a week to dry.  During that time, the surgeon puts something in the eye to hold the retina in place, either a gas bubble or silicone oil.  The gas bubble or silicone oil acts like a clamp and holds the retina in place while the laser adhesion matures.

In addition to laser being used to create and adhesion on a retina that has been reattached, small retinal detachments can be demarcated with laser. Laser does not form a firm adhesion for a week. So it is important to avoid jarring activity for at least one week after laser. Initially, after laser treatment, when the spots are fresh, they do not form an adhesion. Only small retinal detachment can be treated with laser demarcation. This therapy keeps the retinal detachment from extending most of the time. It is safer than surgery, but does not repair the detached retina, it just walls off the detached area. The accompanying photo shows a very unusual case where the detached retina spontaneously re-attached after laser demarcation.

Laser treatment for diabetic macular edema (DME) is often referred to as focal/grid laser photocoagulation. It is a therapeutic approach used to manage and treat DME, a condition where fluid accumulates in the macula, the central part of the retina, due to leaking blood vessels.

Here’s how laser treatment works for diabetic macular edema:

1. Principle of Photocoagulation:
   • Laser photocoagulation involves using a focused beam of light, typically from a laser, to treat specific areas of the retina.
   • The term “photocoagulation” refers to the process of using light to create coagulation or sealing of blood vessels.
2. Focal Laser Photocoagulation:
   • This technique targets specific leaking microaneurysms or abnormal blood vessels in the macula.
   • The laser is applied to these specific areas to seal the leaking blood vessels, preventing further fluid leakage.
3. Grid Laser Photocoagulation:
   • In cases where the swelling and leakage are more diffuse, a grid pattern of laser spots may be applied to a larger area of the macula.
   • This approach aims to reduce the overall fluid buildup and improve retinal function.
4. Objective:
   • The primary goal of laser treatment in DME is to stabilize or improve vision by reducing the leakage of fluid into the macula.
5. Situation for Use:
   • Laser treatment is typically considered when DME is affecting the central vision and there is evidence of fluid leakage in the macula.
   • It may be recommended when other measures, such as strict control of blood sugar and blood pressure, are not sufficient to manage the edema.
   • Focal/grid laser photocoagulation is often used in conjunction with other treatments, such as anti-VEGF (vascular endothelial growth factor) injections.
6. Limitations and Considerations:
   • Laser treatment may not restore vision already lost due to DME, but it can help prevent further deterioration.
   • There can be side effects and risks associated with laser therapy, including a potential reduction in peripheral vision and the development of small blind spots.

It’s important to note that advancements in treatment options for diabetic macular edema continue to evolve, and the choice of therapy is often individualized based on the specific characteristics of the condition and the patient’s overall health. Patients should discuss the potential benefits and risks of laser treatment with their eye care professional.

Panretinal laser photocoagulation, also known as scatter laser treatment, is a therapeutic approach used to manage proliferative diabetic retinopathy (PDR). PDR is a severe complication of diabetes where abnormal blood vessels grow on the retina, often leading to bleeding and the formation of scar tissue. Panretinal laser is employed to reduce the abnormal blood vessel growth and prevent further complications. Here’s how it works:

1. Objective:
   • The primary goal of panretinal laser photocoagulation is to shrink and destroy abnormal blood vessels that have proliferated in the retina. By doing so, it helps to reduce the risk of bleeding and the formation of scar tissue that can lead to severe vision loss.
2. Principle of Photocoagulation:
   • Similar to focal/grid laser treatment, panretinal laser uses a focused beam of light to create coagulation or sealing of blood vessels.
   • However, in this case, the laser is applied to a broader area of the retina, not just specific points.
3. Treatment Area:
   • The laser spots are typically applied to the peripheral areas of the retina, away from the macula (the central part of the retina responsible for detailed vision).
   • By treating the peripheral retina, panretinal laser aims to reduce the oxygen demand of the retina, which signals the body to produce new blood vessels. This helps inhibit the growth of abnormal vessels.
4. Reduction of Ischemia:
   • Ischemia, or inadequate blood supply, is a key factor triggering the growth of abnormal blood vessels in PDR. The laser treatment works by reducing the ischemic areas, thereby decreasing the stimulus for new vessel formation.
5. Situation for Use:
   • Panretinal laser photocoagulation is often recommended in cases of advanced proliferative diabetic retinopathy where there is a significant risk of severe vision loss if left untreated.
   • It may also be considered when other interventions, such as anti-VEGF injections, are not feasible or are not sufficient to control the progression of the disease.
6. Limitations and Considerations:
   • While panretinal laser can be effective in preventing further complications, it may not fully restore vision that has already been lost.
   • The treatment may have side effects, including reduced peripheral vision and night vision. However, the potential benefits in preventing severe vision loss usually outweigh these drawbacks.

It’s important for individuals with proliferative diabetic retinopathy to undergo regular eye examinations and follow the advice of their eye care professionals. The choice of treatment, including panretinal laser, is often based on the specific characteristics of the disease and the patient’s overall health.

Verteporfin injection in combination with photodynamic therapy was initially developed in 2001 to treat abnormal growth of leaky blood vessels in the eye caused by wet age-related macular degeneration (AMD; an ongoing disease of the eye that causes loss of the ability to see straight ahead and may make it more difficult to read, drive, or perform other daily activities), pathologic myopia (a serious form of nearsightedness that worsens with time), or histoplasmosis (a fungal infection) of the eye. Verteporfin is in a class of medications called photosensitizing agents. When verteporfin is activated by light, it closes up the leaking blood vessels. With the advent of injection therapy for choroidal neovascularization, many physicians now use PDT for central serous retinopathy.