Slit-lamp examination of the lids, lashes, conjunctiva, sclera and cornea is important during contact lens fitting and aftercare and for those patients when symptoms or signs suggest the problem may lie with these ocular structures. Diffuse illumination refers to a wide beam that is directed obliquely for general scanning with low magnification in order to maximise the field of view. It is not necessary to have a neutral density filter in place although this may be useful if the patient is photosensitive.