Nowhere in medicine has laser technology been more beneficial to patients than in the treatment of diabetic retinopathy. Lasers produce a light unique in nature. The light is of specific wavelengths and the light waves vibrate together without interference. This light can be microscopically focused, allowing for precise control in treatment. Patients who need laser surgery are seated at a slit-lamp, just as during an examination, and the beam of laser light is focused through a special contact lens held on the patient's eye by the treating ophthalmologist. Both diabetic macular edema and proliferative diabetic retinopathy are treated by laser photocoagulation. While the machine used is the same, the type of treatment, risks and benefits are quite different.
Because this type of laser uses larger and more powerful spots than for macular edema, and several thousand may be applied at several sessions, side effects are greater. Therefore, treatment is withheld until the risk of severe visual loss without treatment outweighs the risks and side effects of the treatment. Reduced side vision and impairment of night vision can occur with this treatment though most patients do not complain of these side effects. The most serious side effect is mildly reduced visual acuity which treatment causes in about 10% of patients. However, when compared to a 50% chance of loss of all vision without treatment in severe proliferative retinopathy, the 10% risk of mild loss makes sense.