We have all met people whose eyes appear unusually large as we view them through their glasses. Their lenses are actually convex magnifying glasses to correct for the problem of hyperopia or farsighted vision. Others might need ‘reading glasses’ and this admission is stating that the person has mild hyperopia.
What is Hyperopia?
The word comes from two Greek roots hyper meaning excess, and opia (optic) meaning eye. It is less commonly called hypermetropia. A hyperopic eye can see distant objects clearly but close objects are out of focus. This is the opposite of nearsighted vision. This is because light is not focusing properly on the retina in the back of the eye. Its focal point is actually beyond the retina.
Hyperopia is caused mainly by three factors. First, the cornea – that clear disk in the front of the eye – could be too flat thus keeping light from focusing soon enough. Second, the eyeball could be too short and thus the retina is closer than the focal point. Both problems are inherited. The shape of the eyeball cannot be corrected but the focal length can. A third cause is common in older people. The lens gets stiff and unable to change shape to adjust to different focal lengths. When it can’t get thicker, the person will need reading glasses.
If a person has hyperopia, he or she can be given convex lenses (fatter in the middle than on the edge) that cause the light to bend in or refract before it enters the eye. This shortens the focal length causing the image to focus on the retina instead of beyond it. This correction can also be accomplished by convex contact lenses. The thin piece of plastic rests on the eyeball and refracts the light inward as it enters.
A Remarkable Solution to Farsighted Vision
In recent years, thanks to the invention and application of laser light, hyperopia can be corrected permanently in many people through Lasik surgery. Einstein developed the concept of laser light and several years later a laser was made. Laser light is a pure wavelength so it does not scatter the way visible light does. This means it can do precise work such as eye surgery.
The Lasik procedure involves cutting a flap in the cornea of the eye and folding it back. Then the laser is used to reshape the back of the cornea to permanently refract the light as desired. With farsighted people, the goal of the Lasik surgery is a steeper cornea, that is, to make the inside more like the shape of a magnifying glass. Many who have this surgery report that within twenty-four hours after the procedure, their vision is remarkably improved or totally corrected.