The availability of ab interno minimally invasive glaucoma surgery (MIGS) has promoted an international interest in this procedure. Our purpose is to define the role of MIGS in the constant evolving glaucoma treatment algorithm. Current MIGS approaches to lowering intraocular pressure (IOP) include increasing trabecular outflow (iStent trabecular microbypass stent, iStent inject, Hydrus Microstent, Kahook Dual Blade goniotomy, Trabectome ab interno trabeculectomy, Excimer laser trabeculotomy, and goniotomy-assisted transluminal trabeculotomy), increasing uveoscleral outflow with suprachoroidal shunts (Cypass microstent), and developing subconjunctival filtration (XEN gel stent and InnFocus microshunt). The efficacy of each depends on the achievement of desired target IOP reduction in a specific patient. The determination of whether a procedure is either a MIGS or minimally effective glaucoma surgery (MEGS) procedure is based on their efficacy and complications. Aqueous humor angiography suggests that success of trabecular bypass MIGS may not be patient-dependent only, but it may be affected by the location and flow of aqueous through collector channels. The future use of aqueous angiography may permit customized treatment of trabecular meshwork dependent MIGS procedures.