Myopia
Myopia, or nearsightedness, is due to light focusing in front of the retina. This premature focal point is typically caused by a longer-than-average eyeball or a steep cornea. Symptoms of nearsightedness include:
- blurred vision at distance
- squinting
- headaches
Spectacles and contact lenses help to diverge light so that it focuses sharply on the retina.
Hyperopia
Hyperopia, or farsightedness, is due to light focusing behind the retina and is due to either a shorter-than-average eyeball or flat cornea. Symptoms of farsightedness include:
- blurred vision at near
- difficulty focusing
- headaches associated with reading or near work
This can be corrected with eyeglasses and contact lenses.
Astigmatism
In astigmatism, light rays focus at different points on the retina making vision at all distances blurred. Astigmatism typically means the cornea is shaped like a football rather than a basketball, having a long curve and a shorter, steeper curve. Symptoms of astigmatism include:
- squinting
- headaches
- pain around the eyes
As with near- and farsightedness, eyeglasses and contact lenses can typically correct blur associated with astigmatism.
Presbyopia
Presbyopia is the process by which the ability to focus is reduced. This typically begins during the fourth decade and progresses into our 50′s. Eyeglasses and contact lenses can help to restore loss of focus.