Determining target intraocular pressure (IOP) in glaucoma patients is multifaceted, requiring attention to many different factors such as glaucoma type, severity of disease, age, race, family history, corneal thickness and hysteresis, and initial IOP. Even with all these variables accounted for, there are still patients who have progression of the disease despite achieving target IOP. Intraocular pressure variability has been identified as a potential independent risk factor for glaucoma progression but is currently difficult to quantify in individual patients. New technologies enabling measurement of both diurnal and nocturnal IOP may necessitate modifying our concept of target pressure.