Understanding Your Prescription: A Guide for Optician Patients

Understanding your eyewear prescription is an important step in knowing and keeping track of your vision and spectacle power from time to time. Whether you have recently begun wearing glasses or contact lenses or have been doing so for years, it's vital to comprehend the fundamentals of your prescription and what it implies for your eyesight.

Everything you need to know about prescriptions, vision conditions and their treatments, as well as tips for selecting suitable lens materials & coatings, is included in this guide.

How to Read Eyeglass Prescription

Here are some basics of how to read your eyeglass prescription: 

Sphere (SPH) Meaning

This column indicates the lens power needed to correct nearsightedness or farsightedness. A minus sign (-) indicates nearsightedness, while a plus sign (+) or no sign indicates farsightedness. The higher the number, the stronger the prescription. 

Cylinder (CYL) Meaning

This column indicates the amount of lens power for astigmatism. Astigmatism is when your eye is shaped more like a baseball than a basketball, which distorts the image. If there are numbers in this column, you need glasses to correct astigmatism. A minus sign indicates nearsighted astigmatism, while a plus sign indicates farsighted astigmatism. 

Axis Meaning

This column indicates the direction of astigmatism. This has more to do with the placement of the lenses and the strength of this number does not indicate whether its good or bad. The axis is measured on a scale of 0 to 180 degrees. 

Add Meaning

This column indicates the magnifying power for multifocal lenses to correct presbyopia. The number is usually a plus power and is the same for both eyes. In the traditional sense, near vision are also known as reading glasses.  But near vision includes all tasks at near including scrolling on the phone, reading on a tablet, workign on a laptop or desk.  Even housework like working in the kitchen or putting a thread through a needle is near vision.  

Prism

This column indicates the power to compensate for eye alignment problems. Prism in an eyeglass prescription is usually indicated by two numbers: the amount of prism correction and the direction of the prism's base:

Prism Correction

The amount of prism correction, measured in prism diopters (PD). For example, 0.5PD, 1.0PD, 1.5PD, and so on.

Prism Base

The direction of the prism's base, which is the thickest edge of the prism. The base can be at the top (Base Up, BU), bottom (Base Down, BD), inner edge (Base In, BI), or outer edge (Base Out, BO) of the lens.

OD and OS

These abbreviations stand for the Latin terms oculus dexter (right eye) and oculus sinister (left eye). Sometimes, OU or ODS is used to indicate both eyes, which stands for oculus uterque or oculus dexter et sinister. 

Some eye care professionals may use more modern abbreviations, such as RE for the right eye and LE for the left eye. 

The left and right eyes are reversed on the prescription to match the optometrist's view of your eyes when they are looking at you face-on.

Common Vision Conditions and Treatments

Myopia

Myopia (nearsightedness) is a common vision condition in which you can see things up close, but things farther away are blurry. A curved cornea or a longer-than-average eye causes this. Myopia can be managed with glasses, contact lenses, or refractive surgery.  One important thing to note and discuss with your optometrist or opticians, if you have children who have myopia is Myopia control spectacle lenses. These are specially designed for children between ages 6 and 18 years to arrest progression of myopia.

Hyperopia

Hyperopia (farsightedness) is another common vision condition in which you can see things clearly from a distance, but things up close are blurry. A flatter cornea or a shorter-than-average eye causes this. Hyperopia can also be managed with glasses, contact lenses, or refractive surgery.

Astigmatism

Astigmatism is a condition in which the cornea or lens of the eye is irregularly shaped, distorting the image. Astigmatism can be managed with glasses, contact lenses, or refractive surgery.

Presbyopia

Presbyopia is a condition that occurs naturally as we age, in which the eye's lens loses its ability to focus on close objects. This condition can be managed with reading glasses, progressive lenses, or contact lenses.

Conclusion

It's important to schedule regular eye exams and communicate with your optometrist or optician about any questions or concerns. Finally, remember that your vision is a precious gift; take good care of it and always keep learning about it. 

FAQs

Q1: How often should I schedule an eye exam?

Ans: Most eye care professionals swear by the adage “Check yearly, See clearly.”  Additionally, it is recommended for children and young adults upto the age of 21 to schedule a vision exam every six months; beyond that, at least once every 12 months. 

Q2: What types of tests will be performed during an eye exam?

Ans: During a vision exam, your optometrist will perform various tests to assess your vision and check for any problems. These tests may include 

• A visual acuity test which measures how well you can see at different distances and 

• A refraction test which determines your eyewear prescription.  

In a thorough eye exam with an ophthalmologist, apart from the vision test, they will check for eye pressure and examine the appearance and health of the internal parts of the eyes using sophisticated lenses and scopes.