What Causes Blurred Vision?



Most of the eye's focusing power is provided by the cornea. The cornea is the transparent "window" at the front of the eye which focuses light rays onto the retina (the nerve layer at the back of the eye). If the optical system of the eye is in perfect focus the eye should be able to see "20/20" vision without the need for glasses.


Causes of blurred vision

On the other hand, if the optical system of the eye is imperfect, the image formed on the retina is not sharp, and the result is blurred vision. By far the most common conditions causing this are myopia (short-sightedness, hyperopia (long-sightedness), or astigmatism. These are termed refractive errors of the eye, which simply means that the focusing (refracting) system of the eye is imperfect.


Refractive surgery is any surgical procedure aimed at correcting a refractive error. Laser eye surgery is the most popular type of refractive surgery nowadays. Other types of refractive surgery, that do not involve a laser, include, lens implants, lens exchange and conductive keratoplasty.


Refractive surgery works by altering the focusing properties of the eye, either by altering the curvature of the cornea, or by implanting a lens inside the eye.



Am I Short-Sighted or Long-Sighted?

Blurred vision is most often caused by the eye having an imperfect focus, or refractive error, such as short-sightedness or long-sightedness.

Check if any of those optical conditions applies to you:

Optical Condition

Cause

Treatment Options

Short-sightedness (Myopia)

  • You have blurry distance vision. You see near objects clearly.
  • Your distance vision seems clearer if you squint.

Eye is too elongated from front to rear, or the cornea has too much curvature.


Light focuses in front of the retina instead of directly on it.


Degrees of severity:

  • Mild (Low):
    < -3.00 diopters
  • Moderate:
    -3.00 to -6.00 diopters
  • Severe(High):
    -6.00 to -9.00 diopters
  • Extreme (Super High):
    > -9.00 diopters

Prescription glasses or contact lenses contoured to compensate for the curvature of the cornea, or laser refractive surgery to re-shape the cornea to reduce its curvature.


In some cases of severe or extreme (high or super high) myopia, a non-laser refractive surgery technique may be advised.

Long-sightedness (Hyperopia)

  • You have trouble seeing near objects.
  • Your distance vision is relatively clear, but it becomes less clear as you get older.
  • You may notice eye fatigue when reading.

Eye is too short from front to rear, or the cornea has insufficient curvature.


Light focuses "behind" the retina, instead of directly on it.


Degrees of severity:

  • Mild (Low):
    < +2.00 diopters
  • Moderate:
    +2.00 to +4.00 diopters
  • Severe (High):
    +4.00 to +6.00 diopters
  • Extreme (Super High):
    > +6.00 diopters

Prescription glasses or contact lenses contoured to compensate for the curvature of the cornea, or laser refractive surgery to re-shape the cornea to increase its curvature.

In some cases, a non-laser refractive surgery technique may be advised.



Do I Have Astigmatism?

Astigmatism is an inability of the eye to focus clearly at any distance because of the shape of the front of the front surface of the eye (the cornea).


Instead of being spherical, like a soccer ball, a cornea with astigmatism is more curved in one direction than the other, similar to a rugby ball.
Almost all eyes have a little astigmatism, but often the distortion is so slight that it does not significantly affect vision. However, if you have more than a small degree of astigmatism it can noticeably blur vision unless glasses are worn.


Astigmatism can occur alone or along with short-sightedness or long-sightedness.



Click the Following link to find out more information on astigmatism.


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Do I Need Reading Glasses?

Presbyopia is the term used to describe the deterioration in reading vision that develops in most people around 45 years of age. You will know when you start to experience presbyopia because you will find that you need to hold the newspaper/menu/book further away to be able to read the text.


Up until around 45 years of age, the natural lens inside your eye can flex to allow clear vision at various distances. But as your eye ages, your natural lens hardens and loses its ability to change shape to focus on near objects. Your distance vision is usually unchanged. This is a normal aging process that can be treated with reading glasses or bifocals. Another option is laser eye surgery using a technique called monovision or blended vision.


Click the following link to learn more about monovision.


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