Bathrooms with windows right above a bath tub or in the shower area are bad news. If you use the shower regularly, you'll eventually damage the window. Replacing that window with glass block will provide the light you desire and help you to fully use your shower again.
Many homes have a typical 5 foot wide x 7 foot long bathroom with either a tub or shower that is visible when entering the room. In addition there is a window in the bath tub or shower area. This limits the shower's use. When one uses the shower, water and humidity over time can destroy a wooden window.