Retinal Laser Surgery

PANRETINAL PHOTOCOAGULATION (PRP)

PRP laser is performed on those patients who have developed bleeding in the eye as a result of their diabetes. Proliferative diabetic retinopathy is characterized by the development of intraocular neovascularization, or new "bad" blood vessels. The risk of developing proliferative disease is directly linked to a patient's duration of diabetes, with 50% of type 1 diabetics developing proliferative findings by 20 years. With an increasing duration of diabetes, the retinal vessels develop progressive damage with large areas of retinal ischemia (meaning lack of oxygen). These ischemic areas are believed to stimulate the release of factors such as vascular endothelial growth factor (VEGF) which lead to the development of intraocular neovascularization. The "gold" standard treatment for patients with proliferative disease is panretinal photocoagulation (PRP). This consists of placing retinal burns to the entire 360-degree retina except the macular region, which serves central vision. By lasering large portions of the peripheral retina the angiogenic stimulus is believed to be removed and the neovascular tissues will often regress.

Often the laser treatment is performed over 2-3 sessions due to the discomfort that frequently accompanies these treatments. Although PRP laser is necessary to control the neovascular process, the burns themselves can cause a slight loss of peripheral vision, difficulty with night vision or an increase in retinal swelling. On the other hand, inadequate treatment allows the neovascular tissues to continue growing which can lead to severe visual loss due to the development of vitreous hemorrhages (bleeding in the "jelly" of the eye) or retina detachments. It is important to note that the development of proliferative diabetic retinopathy is often accompanied by diabetic kidney disease.

FOCAL GRID LASER

A Focal Grid Laser may also be used for diabetic retinal swelling, or edema. Unfortunately, diabetic retinopathy is the leading cause of blindness in working age adults in the western world. The early stages of "nonproliferative" diabetic retinopathy are characterized by the development of retinal hemorrhages and microvascular anomalies. The most common cause of visual loss with diabetic retinopathy is the development of macular edema (or swelling), where micro-vascular anomalies leak fluid and proteins into the retina. Clinically, retina specialists are trained to look at a slit lamp microscope to detect retinal thickening or edema which is vision threatening. This is referred to as clinically significant macular edema (CSME) and requires treatment.

The "gold" standard of care as determined by the early treatment diabetic retinopathy trial (ETDRS) is to perform laser photocoagulation to the areas of retinal thickening. Although the laser treatments are highly effective at drying up the areas of retinal edema, vision improvement rarely occurs--the treatment is done to prevent further loss of vision. This stresses the importance of regular screening of diabetic patients such that laser treatment can be instituted as early as possible, before significant visual loss has occurred. Diabetic eye specialists are often able to convince patients who have developed macular edema and begun to lose vision the importance of tightly controlling their blood sugar and following the instructions of their primary care physician.

Interesting web site link:

http://medweb.bham.ac.uk/easdec/laserdiabetic_retinopathy.html#intro