Although studies in the past have looked at the total societal cost of treating glaucoma, the third leading cause of blindness worldwide, none to date has examined the cost of treating the disease according to its severity. However, the results of a study presented at the 2002 annual meeting of the American Academy of Ophthalmology held in Orlando, Florida, US, suggest that the annual direct cost of treating the condition is more than four times greater at the most severe stage of the disease than it is at the earliest stage. Moreover, a second study has shown that a significant percentage of patients with glaucoma do not take their medications as indicated because of financial concerns.