In bright light, the pupil constricts to reduce the amount of light entering the eye. In dark or dim light, the pupil dilates to allow more light into the eye to improve vision. Normal pupil size tends to range between 2.0 and 5.0 millimeters, depending on the lighting. The younger you are, the larger your pupils tend to be.
Fecal incontinence is commonly caused by altered bowel habits (generally diarrhea, but also constipation) and conditions that affect the ability of the rectum and anus to hold stool. The sphincter muscles become weaker as you grow older.
Constipation is a leading cause of bowel incontinence. In cases of severe constipation, a large, solid stool can become stuck in the rectum. This is known as faecal impaction. The stool then begins to stretch the muscles of the rectum, weakening them.