To give his consent for diagnostic or therapeutic procedures a patient needs information on the nature of the disease, its course and possible complications. Additionally, he needs to be informed about the necessary diagnostic and therapeutic procedures themselves and the possible consequences of omitting them. All the typical risks have to be explained, even though they may be extremely rare. If a procedure is not immediately necessary, the information given has to be more comprehensive than in emergency cases. Therefore, comprehensive information has to be provided for prophylactic procedures (including information leaflets for patients, especially in cases of cataract, glaucoma and retinal detachment surgery, photocoagulation for equatorial degeneration and diabetic retinopathy, as well as vitrectomy and fluorescein angiography). The information must be given by the physician himself and should be as comprehensive as is necessary to enable the patient to decide for himself whether he wants to undergo the procedure. The majority of patients accept the enlightenment is necessary, consider the information supplied adequate and are thus reassured.