Eye conditions are vision issues related to the optical properties of the eye. And the most common vision conditions is refractive errors. Most of us have one refractive error or more, such as having astigmatism and myopia. For some people it’s too small to affect their eyesight. But for others it needs a specific vision correction.
In order to see clearly, your cornea and your eye’s lens bend, or refract, entering light rays and focus them on the retina. The retina then converts them to signals. Finally, the signals are transmitted by the optic nerve to the brain to be translated into images.
If the light rays don’t focus on the retina, the result is blurred vision — a refractive error. Here is the list of the most common eye conditions.
In a normal eye, the cornea is uniformly curved on all sides. If you have astigmatism your eye has an irregularly curved cornea, or sometimes an irregularly shaped eye’s lens.
The irregular shape causes light to bend improperly when it passes through your cornea. The light rays may focus in front of the retina or behind the retina. This situation results in a distorted object. The blurry vision is not always uniformly blurry. Some distances are more out focus than others.
Eye doctors often hear this question. “What is a stigmatism?” This is not the correct spelling. The correct one is astigmatism.
Hyperopia or Farsightedness
When your eyeball is too short or your cornea is too flat, light rays that enter your eye focus behind the retina. If this happens you can see distance objects clearly. But the close ones are blurred because they can’t be focused properly.
Many children are born with hyperopia, but sometimes their vision normalizes as their eyeballs lengthen during the growth process.
Younger persons often see close objects clearly because their eye lenses are adjustable. The lens ability to change shape is called accommodation. As a person ages, the ability to accommodate often lessens.
In term of inability to see close objects clearly, hyperopia is similar to presbyopia. But they have a different underlying cause.
Myopia or Nearsightedness
Myopia occurs when the eyeball is longer than usual. This causes light rays from distance objects to focus in front of the retina, resulting in blurry vision. It can also occur if the cornea is curved too acutely.
If you’re nearsighted you’ll be difficult to see road signs or scoreboards at a sporting event. But you can see up-close activities, such as reading, clearly.
Your myopia severity may vary from mild to severe. If you’re mildly nearsighted you may not be aware of the disorder. But if you’re extremely nearsighted you may only have clear vision up to a few inches from your eyes.
Presbyopia or Aging Eye Conditions
During forties or older, the crystalline lens becomes less flexible. The eye muscles that allow it to accommodate also weakens. As you’re ages, your eye’s muscles can’t help the lens to expand and become rounder to focus on close objects. Your near vision is blurred because the lens can’t resume the shape that it needs to bring them into focus.
If you never had any eye problem you can see distant objects clearly. But if you’re mildly farsighted you may need glasses help to see clearly. You no longer see close objects clearly because your eye’s lenses are not able to accommodate.
So presbyopia is an age-related eye conditions. This is different from astigmatism, nearsightedness and farsightedness. The three eye conditions are related to the shape of the eyeball because of mostly genetic factors.