[Ophthalmological use of pulsated Neodymium Yag lasers. Preoperative aperture of lenses previous setting in of artificial lenses and opening of secondary cataracts behind implants (author's transl)].

A new laser devised and built by the authors is presented. This cold laser is an ultra rapid pulsed Neodymium Yag laser. Its permits a very fine microsurgery without opening of the eye. The opening of the capsule and the softening of the nucleus are one example of the new laser surgery daily performed in Trousseau's Eye Clinic: all the ocular tissues, even uncolored and semi-transparent may be cut without heat with this laser. The mechanism of the action is clear. According to our studies, under such an irradiation, a local instantaneous energy deposit takes place, total ionization of the medium occurs, resulting in the formation of a plasma screen, then, after an hydrodynamic shock wave develops from the energy zone boundary. The elevation of the temperature at the site of the impact cannot exceed 2.10(-3) degree C, which is totally unharmful.