New Laser Technologies

Abstract

Glaucoma laser surgery was initially intended and practiced as a less invasive modification of standard filtration surgery. Pulsed and continuous-wave (CW) laser beams were used to create new outflow paths to lower the intra ocular pressure (IOP). The patency of laser-made openings proved short lasting, but the realization that the reduction of IOP persisted long after their failure prompted the investigation of new techniques and protocols. Lasers were used to produce shrinking burns in the trabecular meshwork (laser trabeculoplasty or LT), to stretch or perforate the iris (laser iridoplasty or laser iridotomy), and to replace diathermy and cryotherapy in cyclodestructive procedures to reduce the production of aqueous humor (laser cyclophotocoagulation or CPC). Treatment endpoint of all laser surgeries was always a discernable photothermal, photoacoustic, or photomechanical tissue effect, such as stretching, blanching, burning, bubbling, popping, perforating, or cutting. Although destructive in nature, the iatrogenic damage and collateral effects associated with these endpoints have been universally accepted as necessary for a useful treatment. Lately, almost by serendipity, it has been found that some procedures result equally effective and more beneficial when performed without destructive endpoint, by eliciting similar mechanisms of action with fewer or no collateral effects. This chapter will briefly review past and current glaucoma laser-surgery procedures and discuss new laser technologies that allow performing novel subthreshold laser-therapy treatments with no discernable tissue reaction endpoint.

Effective subthreshold laser therapies, with less or no iatrogenic damage, can be administered pro re nata (PRN) and play an important complementary role with emerging microinvasive glaucoma surgeries (MIGS) in the long-term management of glaucoma.