At our London, Ontario practice, our optometrists prepare prescriptions for eyeglasses and contact lenses to help correct blurred vision, which can result from a variety of refractive errors.
Why do I need corrective lenses?
Vision blur is the result of a defocus aberration in your eye. It can appear differently depending on the level and type of refractive error.
If you are experiencing vision blur, you may need corrective lenses to help you see clearly and sharply again.
How will my optometrist know if I need vision correction?
During an eye exam, your optometrist will measure your visual acuity using an eye chart. This chart will be displayed at a standardized distance from you when you're being tested.
During the test, you will attempt to identify the symbols on the chart, moving from the largest symbols to progressively smaller ones, until you are unable to identify the remaining symbols.
Based on the smallest symbols you can read on the chart, your optometrist will determine your visual acuity, and write your prescription accordingly.
Fill Your Prescription On Site
At Sharpe Optometry, we'll help guide you through each step of your vision test, and then we'll help you fill your prescription for eyeglasses or contact lenses, too!
We offer a convenient on-site eyeglass dispensary that carries a wide variety of affordable, designer frames.
You can order nearly any frame from any supplier, with a price guarantee.
Making Sense of Your Prescription
Corrective lenses work by focusing light on the retina. This can be done with either contact lenses or eyeglasses.
When reading your prescription, you'll see numbers listed under the headings OS (oculus sinister) for your left eye, and OD (oculus dextrus) for your right eye. In some cases, you'll also see the notation OU, which refers to an issue affecting both eyes.
Essentially, the farther away the numbers on your prescription are from zero, the more vision correction you need. If you see a plus sign in front of the number, that means you are farsighted. If you see a minus sign, it means you are near sighted. These number represent diopters, which are the units of measurement used to determine the level of vision correction, or the power of the lens, that your eye needs.
For instance, if your prescription reads -2.00, you have two diopters of nearsightedness. If it says +4.50, you have 4 and 1/2 diopters of farsightedness.
Astigmatism
If you have astigmatism, you will see three numbers on your prescription, which are typically represented as S x C x Axis. The S refers to the degree of near- or farsightedness described above, or the 'spherical' element of your prescription.
The C refers to your astigmatism. This number can be either positive or negative, and measures the degree of your astigmatism in diopters.
The Axis refers to he orientation of your astigmatism, and can be a number anywhere from 0 to 180 degrees. It shows the location on your eye where the difference in curvature exists.
A prescription for astigmatism will look something like this: -1.50 +2.00 x 180