An in-vivo device may include an optical system, and a method for viewing in-vivo sites. A dome or cover may cover an end of the device, protecting optical elements such as illumination devices or imagers, which may be behind the dome. The dome may be forward projecting and may have a convex shape. The field of view of the imager may be for example forward looking. Illumination element(s) and a receiving unit or imager may be disposed behind a single optical window, which for example may enable obtaining of images free of backscatter and stray light. The convex shape of the dome may be defined such that it may have a shape having an isolated area. At least one illumination element and at least one receiving unit may be geometrically positioned (for example in the isolated area) such that rays from the illumination elements, some of which are internally reflected from the internal and/or external surface of the optical window, will not be incident on the receiving unit.