An ophthalmic laser ablation system is described with various optional features, some especially suitable for non-penetrating filtration on an eye. In one example, focusing of an ablation laser uses a movable lens coupled to a pair of converging light sources, which converge at the focal distance of the lens. In another example, laser ablation settings are selected for optimal ablation and minimal amount of thermal damage of a layer of percolating scleral tissue.
