laser peripheral iridotomy costperipheral iridotomy laser surgeryiridotomy laserperipheral iridotomyyag laser peripheral iridotomyprophylactic laser iridotomylpi laser peripheral iridotomybilateral laser iridotomyperipheral iridotomy procedureprophylactic peripheral iridotomynarrow angle laser iridotomybilateral peripheral iridotomies