Understanding Your Prescription
Have you ever received a copy of your glasses and/or contact lens prescription and wondered what all the different numbers stood for? If yes, keep reading to understand your prescription. By the end of this article you’ll be able to decipher the following example prescription like a pro!
Refractive error refers to a vision problem where the light entering the eye is not accurately focused onto the retina leading to difficulty seeing either faraway, up-close, or both. The retina is the tissue lining the inside of the eyeball, it contains light-sensing cells which convert the light entering the eye into electrical signals that are sent off to the brain to give us sight. The different types of refractive errors include myopia, hyperopia, astigmatism, and presbyopia.
Myopia, or nearsightedness, is a condition where the length of the eyeball is longer than average and/or the eye’s focusing power is stronger than average. Patients with myopia experience blurry vision when looking far away and have clearer vision up close, hence the term “nearsighted”. Myopia can be corrected with glasses, contact lenses, and possibly refractive surgery if the patient is a candidate. A prescription for myopia is written under “sphere” with a minus sign before the number, for example -1.00. Patients with myopia have a greater risk of ocular complications like retinal detachments, maculopathies, or glaucoma. This is due to their eyeballs being longer and retinas being stretched more. For these reasons, we highly recommend patients of all ages to get annual dilated fundus exams to fully assess ocular health. Additionally, we encourage our pediatric population to come in for routine check ups to check for myopia and assess its rate of progression. If a child has myopia that is progressing at an abnormal rate we strongly recommend starting some form of myopia management to help slow down the progression and decrease the chances of acquiring serious diseases in the future. Stay tuned for a post designated for myopia management!
Hyperopia, or farsightedness, is a condition where the length of the eyeball is shorter than average and/or the eye’s focusing power is weaker than average. Patients with hyperopia generally have good distance vision but have a harder time seeing up close, hence the term “farsighted”. Patients with hyperopia can correct their vision with glasses or contact lenses. A prescription for hyperopia is written under “sphere” with a plus sign before the number, for example +1.00.
Astigmatism is a condition where the front surface of the eye is shaped more like an oval instead of a sphere. We like to give our patients the analogy of a basketball versus a football where an astigmatic eye resemble more of a football’s shape. This results in objects appearing blurry at a range of distances. Patients with astigmatism can correct their vision with glasses or contact lenses as well. A prescription for astigmatism can be written with a minus or plus sign before the number depending on if the prescription comes from an optometrist or ophthalmologist. Astigmatism is written under the “cylinder” or “cyl” portion of the prescription and the “axis” notes which direction, or orientation the astigmatic power lies.
Presbyopia is an age-related condition where it gets more difficult to maintain clear vision/focus on near objects like a phone, book, or computer. It is a slowly progressive condition that typically occurs during the ages of 40 to 65. It occurs because the lens inside of our eyes slowly gets less flexible making it harder to maintain focus up-close. When presbyopia first becomes noticeable patients often state that they “have to hold things further away from their face to see them more clearly”. Presbyopia can be managed with reading glasses, progressive glasses, or multifocal contact lenses. The amount of presbyopia is noted in the “ADD” section of the prescription.
Now that you’ve learned about glasses prescriptions go ahead and revisit Jane Doe’s prescription up top and see if you have a better understanding of it. Have fun and let us know if you have any questions about your prescription!