Common Refractive Errors
Short Sighted, Long Sighted, Astigmatism…
What does it all mean?
What causes myopia?
Hyperopia, or farsightedness, is a vision condition in which distant objects are usually seen more clearly than close ones. Farsightedness is due to the eye not bending light properly, so it focuses behind the back of the eye or the cornea has too little curvature. Hereditary factors often control the growth and development of the eye.
Common signs of hyperopia include difficulty concentrating and maintaining a clear focus on near objects, eye strain, fatigue and/or headaches after close work, aching or burning eyes, and irritability or nervousness after sustained concentration.
Astigmatism is an irregularly shaped cornea or lens that prevents light from focusing properly on the retina, the light-sensitive surface at the back of the eye. The surface of the cornea is shaped more like a football instead of round like a basketball and the eye is unable to focus light rays to a single point. In this case, vision becomes out of focus at any distance. In addition, the curvature of the lens inside the eye can change, resulting in an increase or decrease in astigmatism. This change frequently occurs in adulthood and can precede the development of naturally occurring cataracts.
Astigmatism frequently occurs with other vision conditions like myopia (nearsightedness) and hyperopia (farsightedness). Together these vision conditions are referred to as refractive errors because they affect how the eyes bend or “refract” light.
Astigmatism can be hereditary and is usually present from birth or it might develop following an eye injury or eye surgery. It can decrease or increase over time and could possibly occur due to a relatively rare condition called keratoconus in which the cornea becomes progressively thinner and cone-shaped.
Presbyopia is a vision condition in which the shape of the crystalline lens of your eye changes. These changes make it difficult to focus on close objects.
Presbyopia may seem to occur suddenly, but sight reduction occurs over several years. Presbyopia usually becomes noticeable in the early to mid-40s, but the reduction of your focus starts as early as childhood.
Some signs of presbyopia include holding reading materials at arm’s length, blurred vision at normal reading distance and eye fatigue along with headaches when doing close work.
Presbyopia is a natural part of the aging process of the eye. It is not a disease, and it cannot be prevented, but it’s effects on your daily life can be minimized with glasses or a variety of types of contact lenses (bifocal, multi-focal or mono-vision).