The Qur’aan commands Muslim men to lower their gaze from looking at women; and likewise the women to lower their gaze [24:30/1]
Modern research discovered that looking at indecent pictures like porn and naked people has physical harms as well. Psychologists in a Yale and Vanderbilt University study in USA found that after looking at an erotic scene subjects had difficulty processing visual information for a fifth of a second. Such emotion-induced blindness could affect drivers who see a provocative billboard. (Popular Mechanics, Dec 2005)
Allah is Most Wise