A peephole provides a convenient and secure way to see who is on the other side of the door without opening it. Over time, however, that peephole may become scratched or damaged, making it unsightly and of little use, or it may be one of the older models that is easily avoided by visitors on the other side of the door by stepping to one side. Modern peepholes offer a better view and can replace those old, tiny models.
Stand at the inside of the door, looking for two notches on the rim of the peephole. Place a flat-head screwdriver into one of the notches.
Turn the screwdriver counterclockwise to begin loosening the peephole. A peephole assembly is two pieces, one that threads into another. If the assembly is tight, open the door and press on the other side of the peephole while turning the screwdriver counterclockwise in the inner peephole slot, or ask a friend to hold the other side for you. Continue turning until the peephole pieces come out of the door, one on either side.
Blow through the hole to remove dust and dirt.
Unscrew the two halves of a new, similar peephole by turning one portion counterclockwise. Push the piece with the notched rim on the inside portion of the door, positioning the other piece on the exterior side of the door.
Push a flat-head screwdriver into the notch on the peephole and turn it clockwise to tighten the peephole assembly while holding the outside peephole piece in place with your other hand. Wipe the peephole glass with a soft cloth to remove fingerprints.