This set of eye glasses look and work much like a normal set of magnifying lenses, but when willed a jumping spider will launch itself out of one of the lenses and become the new sensor for the wearers vision.  You can will the spider to move in any direction, and it being a jumping spider it moves at a good pace, and can achieve good vantage points.  The vision of the spider really isn’t that great, but not horrible either.  The acuity of a human eye is about 5x greater, but the spider can go under a door and any distance.   The effect lasts as long as the spider lives and the wearer continues to wear the glasses.  If the glasses are removed, focus is brought back to normal, and the magic ceases; the spider is then on his own.  As long as the glasses remain on, the magic will be unbroken,.. it would be fine to sleep with the glasses on.  Long range reconnaissance is theoretically possible.