Retinal Laser
A laser is an instrument that produces a pure, high-intensity beam of light energy. The laser light can be focused onto the retina, selectively treating the desired area while leaving the surrounding tissues untouched. The absorbed energy creates a microscopic spot to destroy lesions or weld tissues together.
Who needs Laser Treatment?
Diabetic Retinopathy
In Diabetic Retinopathy there is leakage of blood, fluid and fat (lipid) from the retinal blood vessels. This causes the retina to swell and eventually deteriorate. Swelling that is close to the center of the retina, the macula, and has certain features is called "Clinically Significant Macular Edema" (CSME). When the swelling is very severe the retina breaks down and blisters or "cysts" of fluid form. This is called "Cystoid Macular Edema" (CME). CME results from long-standing or advanced macular edema. A fluorescein angiogram is a test performed to detect the leaks in the retinal circulation. In this test the patient receives special dye injected into a vein in the arm. The retina is photographed with a special light which causes the dye to "light up" the normal and abnormal blood vessels. This provides a road map to guide the surgeon to direct focal laser treatment at the leaking blood vessels in the macula. The laser light focally closes up the leaks, stopping the retinal swelling in the center of vision. Focal laser treatment helps to prevent loss of vision. In certain cases an injection of steroid into the eye is required to help treat retinal swelling. The purpose of focal laser and intraocular injections of steroids is to prevent further visual loss. Some patients do experience improvement of vision.
Branch Retinal Vein Occlusion (BRVO)
BRVO is the most common cause of retinal vascular occlusive disease. A patient may note no change in their vision, slight distortion or profound visual loss. Segmental swelling and blocked blood vessels are typical of a BRVO. A fluorescein angiogram, a study that looks at the circulation of the eye is used to evaluate macular edema and ischemia. This helps to determine if laser treatment is needed. Laser photocoagulation helps seal the leaking capillaries to promote resolution of the macular edema to prevent further visual loss and hopefully improve vision.
Treating the "wet" form of Macular Degeneration
A national study called The Macular Photocoagulation Study, or MPS, demonstrated that targeted laser destruction of abnormal blood vessels, choroidal neovascular membrane or "CNVM," could reduce the risk of severe visual loss. This effect was diminished or lost in patients with high blood pressure and smokers. Forty percent of patients receiving laser lost 2 or more lines of vision. The CNVM grew back in well over half of the patients and this was increased with cigarette smoking. The study also found that the presence of certain types of drusen and pigmentation in the fellow eye was predictive of the development of a CNVM in the other eye.
Stopping "dry" Macular Degeneration
There are new treatments to prevent or slow the development of the dry form of Macular Degeneration. Recent research has studied low intensity laser treatment on the retina and specifically targeted at drusen. In preliminary studies, this type of treatment reduced or eliminated drusen in 80 percent of patients. In these "responders," the majority has improved or stable vision at 1 year. The long-term benefits and side effects of use of this treatment have yet to be determined. Chester County Eye Care is part of a multi-center national trial examining the effect of the diode laser to treat "dry" Macular Degeneration. Additionally, new drugs targeted to effect growth factors may have our role in slowing or preventing macular degeneration.
Retinal Tears and Detachment
The vitreous can pull on the retina as it separates, stimulating the retina, which is perceived as flashes of light. Very rarely, the vitreous may tear a retinal blood vessel and cause a small bleed or hemorrhage, which is perceived as a shower of spots or floaters or haze. If the vitreous rips the retina, this retinal tear will allow liquid vitreous to fall behind the retina. As the fluid falls behind the retina, the retina separates from the back of the eye. The retina begins to lose its function and this is perceived as a curtain or veil over the vision. This is called a retinal detachment. Your doctor will try to find the retinal tear that caused the retinal detachment develops. The examination involves dilating the pupil and looking at the vitreous and retina. This involves pressing on the peripheral retina, and thus the eye, called scleral depression. If the retinal detachment has already occurred, your doctor may use lasers to "weld" around retinal tears once surgery has caused the retina to return to its natural position.