Science & the Virgin of Guadalupe Read what science has discovered about the tilma of the Virgin of Guadalupe Download a high-resolution image of the Our Lady of Guadalupe here 1. Ophthalmic studies made on the eyes of Mary detected that when the eye is exposed to light, the retina contracts, and when the light is withdrawn, it returns to a dilated state, just as happens with a living eye. 2. The temperature of Juan Diego’s tilma, made of a material that comes from fibers of the maguey cactus, maintains a constant temperature of 98.6 degrees, the same as that...