Written on Mar 4, 2009 at 10:09 PM by LASIK Guider
1 Comment


are the simplest and safest means of correcting a . Knowing your eyeglass or contact lens prescription is an important step in knowing if is suitable for you.


After an eye examination, your doctor will give you a prescription representing the required amount of correction in each eye. When eye care professionals (ophthalmologist or optometrist) write an eyeglass prescription, they use a standard format, so it can be interpreted worldwide.

When you look at an eyeglass prescription (Figure 1), you will find that it contains many numbers and different terms. Let’s start to simplify and explain what these numbers and terms represent.

Eyeglass Prescription

Abbreviations and Terms Used in Eyeglasses Prescriptions:

  • O.D. (Oculus Dextrus): is a Latin abbreviation; stands for right eye.
  • O.S. (Oculus Sinister): is a Latin abbreviation; stands for left eye.
  • O.U.(Oculi Uterque): is a Latin abbreviation; stands for both eyes.
  • D.V.(Distance Vision): represents the part of the prescription required to improve far vision.
  • N.V.(Near Vision): indicates the part of the prescription required to improve near vision (e.g., reading). In some prescription, this part is named “Reading”. Alternatively, a single box named ADD is used in some prescription forms instead of the near vision, to indicate the extra dioptric power to be added to the sphere of each eye.
  • SPH.(Sphere): represents the amount of correction needed to normalize vision. A minus sign (-) before the number indicates myopia (nearsightedness) and a plus (+) sign indicates hyperopia (farsightedness). The larger the number written here, the poorer your vision and the stronger (thicker) corrective lenses you need.
  • CYL.(Cylinder): If present, this indicates the degree of astigmatism. It can be preceded by a plus or minus notation.
  • Axis: describes the angle in degrees of one of two major meridians of astigmatism (i.e., the direction of astigmatism). The axis value can range from zero to 180 degrees.
  • I.P.D or P.D.(Inter- Pupillary Distance) is the distance between pupils, usually written in millimeters. If the prescription contains both far and near vision corrections, there will be two PD values one for far vision and another for near vision.

Eyeglasses Prescription Example:

The prescription shown in the above image means that in the right eye, the person has 4 diopters of nearsightedness with 1.5 diopters of astigmatism and an axis of 90 degrees. While in the left eye, he has 3 diopters of nearsightedness with 2.0 diopters of astigmatism and an axis of 60 degrees. In addition, a near vision correction is needed by adding extra +2.0 diopters to the spherical correction.

The full series of LASIK Vision Correction Explained tutorials are , , , ,, , , , and .


Youreyesite May 7, 2009 at 5:31 PM  

How to Care for Your Reading Glasses

No matter which style you choose, some basic care will be required to minimize lens scratches and keep the frame and nose pads clean.
1. Wet lenses on both sides before wiping clean
Always use a soft, 100% cotton cloth (not a shirt!)
2. Launder the cleaning cloth regularly to remove debris
3. Always use an approved cleaner, or soap and water
4. Wash the entire frame in warm soapy water when dirty
5. Have plastic nose pads replaced often
6. Always store glasses in the case provided
7. Never leave glasses in a hot car or direct sunlight
8. Have your glasses adjusted every few months to ensure comfort

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