Refractive Conditions for Which Glasses Are Prescribed

Hyperopia (“Farsightedness”)

Far away things are seen with less effort than near things. Consider this eye small. Small amounts of hyperopia are normal for infants, children and young adults. It is usually outgrown as they reach their twenties. Small amounts are overcome with focusing effort. This is automatic and requires no conscious effort. Spectacle correction may be needed for moderate or large amounts of hyperopia or for focus related crossing of the eyes (accommodative esotropia).

Myopia (“Nearsightedness”)

Near things are seen with less effort than far things. Consider this eye too long. Images come into focus in front of the the retina (the “seeing” part in the back of the eye). Glasses (or contact lenses) are usually worn to compensate for more than small amounts.

Astigmatism

This eye can be considered “out of round” (for example, consider the shape of the back side of a spoon). It is usually the result of unequal surface curves of the clear, front part of the eye called the cornea. Small amounts sometimes do not require glasses. Glasses (or toric contact lenses) are usually worn to correct the image blur.

Presbyopia

Far away things are seen clearly, but magnification is needed for near. This usually begins to occur in patients over 40 years. The eye is normal size and shape, with a “fatigued” near focus mechanism. It is the result of the loss of elasticity in the lens of the eye.

Anisometropia

When the focusing power is different between the two eyes it is called anisometropia. Small amounts may not require correction. Larger amounts may need correction to avoid amblyopia (lazy eye) in childhood and to avoid asthenopia (eye fatigue) at a later age.