Retroflection

Retroflection is a term used in several fields to describe a backward bending or turning. In anatomy and medicine, it refers to the anatomical position of an organ. For example, the uterus can be described as anteverted (bent forward) or retroverted (bent backward). Similarly, the cervix can be retroverted. This positioning is a common anatomical variation and usually does not cause any health problems. However, in some cases, a severely retroverted uterus can be associated with certain symptoms such as painful intercourse or difficulty with menstruation. Medical examinations, including pelvic exams and imaging like ultrasound, are used to determine uterine position.

In optics, retroreflection is the phenomenon where light is reflected directly back towards its source. This occurs when a surface is illuminated by a light source, and the reflected light travels back along a path parallel to the incident ray. Retroreflective materials, such as those used in road signs, safety vests, and bicycle reflectors, are designed to achieve this effect. They typically consist of a layer of small glass beads or prisms that reflect light back to the observer. This is distinct from a simple mirror, which reflects light diffusely in many directions. The effectiveness of retroreflection is measured by its luminance factor.