Method and apparatus for performing surgery on tissue wherein a laser beam is applied to the tissue

An apparatus for performing surgery on biological pathological tissue in a region of nonpathological tissue with the aid of a laser beam applied to the pathological tissue, the apparatus comprising:

• laser means for generating the laser beam with a predetermined wavelength and being adapted to apply pulses of laser radiation intermittently to the pathological tissue;
• transmission means for transmitting the laser beam to the site of the operation to produce a laser focus wherein the energy density in said focus is above a level to cause photoablation whereby secondary radiation is produced capable of causing damage to the nonpathological tissue;
• said secondary radiation being radiation of the laser beam backscattered from the eye or fluorescence radiation of the tissue;
• suction/irrigation means for removing the tissue ablated by the laser beam;
• metering unit means for metering an organic-tissue penetrating substance to said site which is absorbent in said wavelength of said laser beam and which provides a reduced effective threshold for removing by photoablation the pathological tissue;
• said substance being absorbent in the range of the wavelength of the laser beam and which increases photoablation while at the same time protecting the nonpathological tissue not treated by said laser beam against damage by said secondary radiation;
• measuring means for measuring the secondary radiation backscattered from the tissue to detect when the backscattered radiation drops or exceeds predetermined limit values selected to reduce damage to the nonpathological tissue;
• and,
• an electronic control unit which causes said substance to be applied to the pathological tissue during the time intervals between said pulses.

A method for performing surgery on the eye having pathological and nonpathological tissues while protecting the nonpathological tissue against secondary radiation during the surgery, the method comprising the steps of:

• generating a pulsed laser beam of a predetermined wavelength;
• focussing the laser beam on the tissue of the eye to be treated while generating an energy density at the focus adequate for photoablation whereby a secondary radiation is generated capable of causing damage to the eye tissue;
• and,
• applying an organic-tissue penetrating substance to the pathological tissue of the eye to provide a reduced effective threshold for photoablation of the pathological tissue and also applying the substance to the surrounding nonpathological tissue of the eye;
• said substance being absorbent in the range of the wavelength of the laser beam and which increases photoablation while at the same time protecting the nonpathological tissue not treated by said laser beam against damage by said secondary radiation.

A method for performing surgery on the eye having pathological and nonpathological tissues while protecting the nonpathological tissue against secondary radiation during the surgery, the method comprising the steps of:

• generating a pulsed laser beam of a predetermined wavelength;
• focussing the laser beam on the tissue of the eye to be treated while generating an energy density at the focus adequate for photoablation whereby a secondary radiation is generated capable of causing damage to the eye tissue;
• applying an organic-tissue penetrating substance to the pathological tissue of the eye to provide a reduced effective threshold for photoablation of the pathological tissue and also applying the substance to the surrounding nonpathological tissue of the eye;
• said substance being absorbent in the range of the wavelength of the laser beam and which increases photoablation while at the same time protecting the nonpathological tissue not treated by said laser beam against damage by said secondary radiation;
• and,
• said laser beam being generated by a laser having a wavelength in the ultraviolet spectral range and said substance being a drug absorbent in said spectral range.

A method for performing surgery on the eye having pathological and nonpathological tissues while protecting the nonpathological tissue against secondary radiation during the surgery, the method comprising the steps of:

• generating a pulsed laser beam of a predetermined wavelength;
• focussing the laser beam on the pathological tissue of the eye to be treated while generating an energy density at the focus adequate for photoablation whereby a backscattered secondary radiation is generated capable of causing damage to the nonpathological tissue of the eye;
• and,
• applying an organic-tissue penetrating substance to the pathological tissue of the eye to provide a reduced effective threshold for photoablation of the pathological tissue and also applying the substance to the surrounding nonpathological tissue of the eye;
• said substance being absorbent in the range of the wavelength of the laser beam and which increases photoablation while at the same time protecting the nonpathological tissue not treated by said laser beam against damage by said secondary radiation;
• measuring the secondary radiation backscattered from the eye to detect when the backscattered radiation drops or exceeds predetermined limit values selected to reduce damage to the nonpathological tissue;
• switching the laser beam off when the backscattered radiation drops or exceeds the predetermined limit values;
• applying the organic-tissue penetrating substance anew to the pathological and nonpathological tissues;
• and,
• switching on the laser beam to again focus the beam on the pathological tissue of the eye to be treated.