What Is Vertex Depth?
Vertex depth is the distance from the front of the cornea to the backside of an ophthalmic lens. As seen in Chapter 1, the eye is a series of lenses, or a focusing system. The cornea is a lens, the crystalline lens is a lens, and even the vitreous humor, the clear gel-like substance that supports the eye’s structure, has an index of refraction, and can focus or alter the path that light takes through the eye. The eyes work in the same way that a pair of binoculars does. A pair of binoculars has a knob that lets you move a lens inside, so you can focus on objects at different distances. Instead of a knob, the human eye uses the crystalline lens and the brain to adjust for different distances. However, if an ophthalmic lens is placed in front of the eye, it will alter the eye’s natural focusing system. If a person has a refractive error and a lens of the correct power is placed in front of their eye, then the person will have great vision. If too much power or too little power is placed
