What is laser photocoagulation and what effect does it have?

Need more info: Are you asking about retinal laser photocoagulaton, say for diabetes? Diabetic retinopathy has two stages which may be treated with laser photocoagulation; macular edema, the most common, and proiferative diabetic retinopathy are both treated differently by the same laser. "focal" laser is used to treat the leakage whereas "prp" is used to treat patients with proliferative diabetic retiopathy.