Glaucoma and Corneal Thickness. Glaucoma is a leading cause of blindness in the United States. N. Ehlers measured the corneal thickness of eight patients who had glaucoma in one eye but not in the other. The results of the study were published in the paper “On Corneal Thickness and Intraocular Pressure, II” (Acta Opthalmologica, Vol. 48, pp. 1107–1112). The following are the data on corneal thickness, in microns.

Patient Normal Glaucoma 1 484 488 2 478 478 3 492 480 4 444 426 5 436 440 6 398 410 7 464 458 8 476 460 At the 10% significance level, do the data provide sufficient evidence to conclude that mean corneal thickness is greater in normal eyes than in eyes with glaucoma?