Common Vision Problems

The primary function of your eye is to focus light. You need glasses or contacts when your eye cannot properly direct light rays on the retina. The cornea, at the front of your eye, provides most of the eye's focusing power. The lens inside your eye provides the fine tuning of light, contributing to your ability to read. Light rays must focus precisely on the retina for you to see clearly.

If you wear corrective lenses, you may have one of the following common refractive problems; Myopia, Hyperopia, Astigmatism, and or Presbyopia.

Myopia

Myopia (Nearsightedness) occurs when your eye is too long in relation to the curvature of your cornea. With myopia, near objects are seen more clearly than distant objects.

More than 70 million people in North America (about one in four) are nearsighted. Myopia is the medical term for nearsightedness. It occurs when your eye is too long in relation to the curvature of your cornea. Myopia causes light rays entering the eye to focus in front of the retina, producing a blurred image.

The term "nearsighted" means that you can see objects that are "near" to you more clearly than distant objects. The more myopic you are, the more blurred distant objects appear, the higher your prescription in diopters and the thicker your glasses.

Below shows the categories of severity for myopia:

Mild Myopia < -3.00 diopters

Moderate Myopia -3.00 to -6.00 diopters

Severe Myopia -6.00 to -9.00 diopters

Extreme Myopia > -9.00 diopters

 

 

 

 

 

 

 

Hyperopia

Hyperopia (Farsightedness) occurs when your eye is too short in relation to the curvature of your cornea. With hyperopia, distant objects are seen more clearly than near objects.

Hyperopia is the medical term for "farsightedness." Hyperopia occurs when your eye is too short in relation to the curvature of your cornea. Light rays entering your eye focus behind the retina, producing a blurred image. Some farsighted people can use their focusing muscles to pull the image forward onto the retina, allowing them to see clearly. But others, who cannot overcome the effects of severe hyperopia, need glasses for distance vision as well as reading glasses or bifocals.

Below shows the categories of severity for hyperopia:

 

Mild Hyperopia < +2.00 diopters

Moderate Hyperopia +2.00 to +4.00 diopters

Severe Hyperopia +4.00 to +6.00 diopters

Extreme Hyperopia > +6.00 diopters

Astigmatism

Astigmatism occurs when your cornea is shaped like an oval. With astigmatism, more than one focal point within the eye distorts what you see.

 

Many patients with myopia and hyperopia have some degree of astigmatism, or an oval shape, to their cornea. It occurs when your cornea is shaped more like a football than a basketball. As a result, you experience distortion or tilting of images due to the unequal bending of light rays entering your eyes. People with high degrees of astigmatism have blurred vision for both near and distant objects.

 

Below shows the categories of severity for astigmatism:

 

Mild Astigmatism < 1.00 diopters

Moderate Astigmatism 1.00 to 2.00 diopters

Severe Astigmatism 2.00 to 3.00 diopters

Extreme Astigmatism > 3.00 diopters

 

 

 

Presbyopia

Presbyopia occurs as you reach your 40's or 50's. The lens inside your eye loses its elasticity, making it more difficult to read smaller print. Because laser vision correction does not deal with the lens of your eye, it can not correct this problem.

Presbyopia is part of the normal process of aging. It develops as the lens of the eye loses some of the flexibility that characterizes a younger eye. Everyone experiences the effects of presbyopia, typically between the ages of 40 and 50. Nearsighted people who become presbyopic may require bifocals in their forties, and those who never needed glasses before may require reading glasses.

Mild myopia counteracts presbyopia. That is why, if you're slightly myopic with presbyopia, when you remove your glasses you may still be able to read. Laser vision correction may treat your myopia, but you may need reading glasses for fine print to correct your presbyopia. Some presbyopic patients opt for monovision.

Every patient and prescription at TLC is looked at individually to decide what is best for them. TLC doctors are very prudent and thorough in deciding whether you are a good candidate for laser vision correction and will be happy to discuss the potential outcome and risks involved for a patient with your particular prescription.

 

For more information on Presbyopia visit our TLC LASIK blog.

 

Every patient and prescription at TLC Laser Eye Centers is looked at individually to decide what is best for them. TLC Laser Eye Center doctors are very prudent and thorough in deciding whether you are a good candidate for LASIK laser vision correction and will be happy to discuss the potential outcome and risks involved for a patient with your particular prescription.