Biomedical subjects
Publications and source records attributed to K E Schirmer.
Tests on blood agar and human tissue prove that the combined simultaneous dual laser action of a thermal and an optical breakdown mode laser ablates tissue by a mechanism of mutual enhancement of each laser's effect. The force of pressure and the energy of heat combine to ablate tissue in sclerostomy and iridotomy procedures without inducing bleeding.
The rapidly alternating combination of Nd:YAG laser power of the optical break-down mode with cw energy of the argon laser ablates tissue. Blood agar provides a standard test medium as tissue substitute and permits to quantify the effect of various laser energy combinations to achieve optimal ablation. High wattage of the Nd:YAG laser provides destructive pressure that creates fissures which act as the light traps of a black body simulator for efficient cw argon laser energy conversion to pressure and kinetic energy. Within the fissure the deposited cw argon laser energy is directed by gradients toward the tissue surface so that deepening troughs or tunnels are formed by expelling tissue debris.
Laser iridotomies at the base of the iris provide a free shunt between the anterior and the posterior chamber remote from the capsule of the lens. Injury to the lens capsule by the Nd:YAG laser is avoided as the iris is not in close apposition. The heterocentric applanatic lens guides the laser beam under the limbal shelf toward the root of the iris. The combined use of a thermal and an ionizing laser is preferred.
Alternation of the thermal argon laser and the Nd:YAG laser in the optical breakdown mode delivered by means of a slitlamp microscope achieves partial or complete scleral perforation without bleeding.
A heterocentric aplanatic contact of one piece has been designed for optimal efficiency of laser surgery for ALT and YLT in the angle of the anterior chamber.
The ocular of any microscope may be used for the purpose of photography through the device if the camera utilizes the given optical conditions like an observer eye concerning aperture and focal length.
Retinitis proliferans in the diabetic that can not be prevented by PRP can be attributed to insufficient treatment. Examination by means of fundus microscopy, stereochronoscopy of the macula, and computerized perimetry are of prognostic value. Increased PRP should be performed prior to any decision for vitrectomy.
Convex-surfaced contact lenses increase the power of the laser optically for surgery on the iris. Their power-increasing faculty becomes obvious by their power of image magnification. When linked by functions, lens power, laser power, and magnification increases. The laser power, which is multiplied by the lenses, contains a safety feature for the tissues outside the focus of the laser beam as the beam increases in angle. Safety and power is gained by the appropriate use of power-multiplying contact lenses for argon laser surgery.
Treatment of the narrow angle in angle-closure glaucoma depends on iridectomy and mechanical opening of the angle if an argon laser is used for photocoagulation. The effect of the heat is to shrink the iris tissue (gonioplasty) and to free the angle. Maximum power and safety of the laser beam are achieved by utilizing convex contact lenses on the cornea.
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Gullstrand's fundus microscopy is adapted for slit-lamp microscopy without a contact lens, equipped by a wide-aperture argon laser beam. The z axis magnification of the image is used to advantage for vitrectomy. The mobility of the device permits vitrectomy on a fixed eye.
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Goldmann's chronoscopy, a form of time-based photogrammetry of the optic disc, can be accomplished by repeated simultaneous stereophotography. The variations in centration and image orientation are nulled by azimuthal rotation and fusion of two pairs of stereophotographs taken at separate times.
The Hruby-lens may be used as a contact lens with the plano surface in contact with the cornea and the concavity facing the microscope. The observer surveys a large field of the fundus. By decentering the lens, adjacent and peripheral areas of the fundus are drawn into the observer's field. This increases further the total area of fundus that can be observed.
Simplified photogrammetry of the optic disc depends on axis-correct fundus photography. The evaluation can be initiated by a time-based method of photogrammetry that proves presence or absence of change of the object. The degree of change can be simply measured by a telemetric device that permits one to evaluate the third dimension from stereophotographs.
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Explore the source record for details and available documents.