How to read your eyewear prescription.

Not everyone is suitable for laser vision correction. However, at Adelaide Eye & Laser Centre, using advanced laser technology and surgical techniques we can now treat over 95% of eyes with refractive errors.

Among the guidelines for laser vision correction at Adelaide Eye & Laser Centre are:

• Myopia (shortsightedness) up to -10.00 dioptres with astigmatism up to -6.00 dioptres (range extended in special circumstances), or -10.00 dioptres sphere equivalent.
  
• Hypermetropia (long-sightedness) up to +6.00 dioptres with astigmatism up to -6.00 dioptres or, up to +6.00 dioptres sphere equivalent.
  
• Astigmatism up to a maximum of -6.00 dioptres cylinder.

So, are you long or shortsighted? Do you have astigmatism? How do you know from your prescription if you fall within these ranges?

The following is a brief guide to understanding your prescription and determining if you might be a candidate for Laser Vision Correction at the Adelaide Eye & Laser Centre.

Normally your eye care practitioner will write down your eyesight prescription at your eye test, starting with the right eye. This is usually abbreviated with a RE or OD (oculus dextrus). The left eye is usually abbreviated to LE or OS (oculus sinister).

The prescription usually has a number of column headings, these include “Sphere”, “Cylinder” (or “cyl”) and “Axis” and sometimes “Add” or “Prism”.

· The “Sphere” column indicates your level of long or shortsightedness, a “+” indicating Hypermetropia (long-sightedness) and a “-“ indicating Myopia (shortsightedness).

· The “Cylinder” column indicates the measurable amount of astigmatism present, or the difference between your corneas steepest and flatest curves measured in a unit called dioptres.

· The “Axis” refers to the orientation of the astigmatism.

· The “Add” measurement relates to the level of presbyopia or the magnification needed for reading glasses or bifocals.

· The “Prism” measurement relates to how the eyes align in relation to each other. Prism is an uncommon measurement.

The higher the numbers the stronger the prescription.

Your glasses prescription and contact lens prescription will differ slightly. This is due to the contact lens being physically closer to your eye, usually resulting in a slightly different prescription to your glasses. Also your contact lens prescription doesn’t always show your degree of astigmatism.

The following is an example of a prescription:

This prescription is read:

“Right eye, -2.75, -1.00 axis 180.
Left eye, -2.50, -0.50 axis 180. Add +2.25”.

This means that the person is shortsighted or myopic (indicated by the " –" sign in front of the sphere measurement), with a slight astigmatism at an axis of 180 degrees from the horizontal. There is a reading addition of +2.25 indicating presbyopia.

The “Sphere equivalent” measurement is achieved by adding half of the cylinder to the sphere. So in the case above the sphere equivalent is:

RE: (-)1.00 / 2 + (-)2.75 = (-)3.25 and
LE: (-)0.50 / 2 + (-)2.50 = (-)2.75

To enter your glasses prescription into the Prescription Calculator click here and then submit it to AE&LC to see if you might be eligible for laser vision correction.

Adelaide Eye & Laser Centre clinical staff are happy to help you decipher your prescription and determine if you are a possible candidate for Laser Vision Correction. Simply contact us on 1300 366 564 or email us at enquiries@aelc.com.au to speak to one of our Clinical Advisors. Likewise, if you do not fall into the prescription range recommended above, you may be eligible for other forms of refractive surgery, so please contact us if you would like to explore all options.