The cornea and the lens are like a tag-team as they bend light together, focusing it on the retina. This bending of light, known as refraction, is measured in dioptres. Aging causes the refractive power of the lens to decrease, whereas aging does not affect the refractive power of the cornea. Unlike the sclera, the cornea is comprised of is made up of thin collagen fibers that measure 30 nm in diameter. Thus, the cornea is clear as compared to the opaque sclera.