The CO2 laser cuts tissue by flash boiling extracellular or intracellular water molecules in contact with the beam. This vaporization sterilizes the tissue and seals capillaries. The CO2 laser seems most useful in ophthalmology to vaporize lymphangiomas and capillary hemangiomas and to provide hemostasis in patients with bleeding disorders. The cutting beam of the CO2 laser can be attached to the operating microscope to facilitate surgery deep within the orbit. The effectiveness of the CO2 cutting action depends upon water content of the tissue rather than tissue color as with argon and krypton lasers. Skin incisions show less scarring when made with conventional scalpel, but more precise surface cutting lasers may allow more precise microsurgical excision of eyelid tumors than can now be accomplished with a scalpel.