Currently the slit lamp is used to investigate the anterior ocular surface both in normal eye examinations and with contact lenses. It is important to be able to understand the methods of illumination used in a normal slit-lamp routine, in order to get the most out of this instrument, as the smallest of irregularities can be seen. Magnification and the use of stains, especially fluorescein, help make the slit lamp a vital tool in the investigation of anterior eye health.