Liquid light guide catheter having biocompatible liquid light guide medium

A method of delivering light energy to target matter in a mammalian body, the method comprising:

• positioning an open-ended catheter to face the target matter inside the mammalian body;
• pumping a liquid having an ion concentration that is isotonic with mammalian blood from a reservoir and through the open-ended catheter to the target matter, and creating a liquid optical channel between the catheter and the target matter with the liquid, the liquid optical channel surrounded by blood in the body to transmit the light energy from the catheter to the target matter through the liquid optical channel;
• activating a light source to generate the light energy;
• and
• transmitting the light energy through the liquid optical channel to the target matter by total internal reflection and ablating the target matter with the light energy, wherein the light energy has a wavelength in a range of 305-310 nm, the liquid includes magnesium and chloride ions and has an index of refraction in a range of 1.33-1.42 for the wavelength, and the index of refraction of the liquid is at least 5% higher than an index of refraction of the catheter and is higher than an index of refraction of the blood in the body.