Glaucoma is the second leading cause of blindness in the world after cataract, affecting approximately 70 million people, about half of whom are estimated to have open-angle glaucoma.¹ Nearly as many people have angle-closure glaucoma, a disorder that is particularly prevalent among Asians. In open-angle glaucoma, there is no apparent obstruction to the movement of aqueous humor, whereas in angle-closure glaucoma contact between the iris and lens forms a physical barrier to the passage of aqueous humor from the posterior to the anterior chambers of the eye. Among persons of European and African ancestry in the United States, open-angle glaucoma . . .