Confocal microscopy creates a scanned image from a point light source and point detection or a scanning slit to remove scattered light and improve optical resolution. This also results in optical sectioning of tissues. These capabilities can be employed to image structures in the human cornea, in vivo, both for research and for the diagnosis and treatment of human disease. Optical sections, when recombined, can lead to three-dimensional reconstructions from which very useful information is obtained. Investigators have found keratocyte density decreases from anterior to posterior in the stroma of the rabbit cornea. Surface epithelial desquamation can also be studied and the effects of contact lens use can be demonstrated. The instrument is also useful for diagnosing and guiding therapy for some human diseases such as Acanthamoeba keratitis. Colonies of bacteria may also be observed and treatment evaluated in patients with infectious crystalline keratopathy. Confocal microscopy can also image the retina.