Are you struggling with entering your prescription while ordering prescription glasses online? If you are new to glasses and wondering what all the different terms and numbers on your eye prescription mean, we are here to help you today. Let’s break down the details of your glasses prescription, so that you can make an informed decision.

Understanding the basics of a glasses prescription

Here’s what the key terms on your glasses prescription mean:

1. What does Rx mean?

Rx is a universally accepted abbreviation for a medical prescription. It’s just a heading or customary superscription on your glasses prescription.

2. What does SPH (Sphere) mean?

Measured in dioptres (D), Sphere or SPH is the ‘+’ or ‘–’ sign that’s mentioned on your eye prescription, followed by a number. SPH goes up in steps of 0.25. If you face difficulty in seeing nearby objects, your prescription power will be ‘+‘, indicating that you are long-sighted. However, if you struggle to see distant objects, your prescription power will be ‘–‘, implying that you are short-sighted.

3. What do CYL (Cylinder) and Axis mean?

CYL or CYLINDER on your glasses prescription suggests if you have astigmatism (a common eye condition where the cornea or lens of your eyes has an irregular shape, causing distorted vision) and to what degree. It’s mentioned in the ‘+’ or ‘–’ format and the minimum value is +/-0.25 for spectacle prescriptions. On the other hand, AXIS (ranging  from 1 to 180 degrees) indicates the proper position to place the CYL.

4. What do ADD, PD and other terms indicate?

• ADD: It’s an extra value to SPH for patients who need additional nearby vision correction for reading, mostly those struggling with presbyopia. Also referred to as near addition, near add or NV, this value goes up in steps of 0.25 and can range from +0.25 to +4.00.

• PD: PD or Pupil Distance is the distance between your eyes, which is generally measured from the centre point of one pupil to the other. This is important information to enter when ordering your glasses, as it ensures that your vision is clear and comfortable.

• Prism: Sometimes, there’s a muscle imbalance in the eyes, causing double vision and headaches. For such patients, the optician adds a Prism in dioptres. This value can be written in decimal or fraction form with the required direction.

• Base: This value is mentioned to inform the lab about the exact position of the Prism in your glasses.

• Some other simple terms that might not be a part of your prescription are:

1. OS – left eye
2. OD – right eye
3. OU/ODS – both eyes
4. BAL – balance
5. VA – visual activity
6. BVD – back vertex distance

Did you know this about your glasses prescription?

• Validity – From the date of diagnosis, a spectacle prescription is considered to last for about 1-2 years. According to expert opticians, it is recommended to have your eyes checked every 2 years. That said, you must immediately schedule a thorough eye checkup in case of any vision difficulty or discomfort, even if your glasses are of the latest prescription.

• Frame choice – Even though most people consider their personal preference and face shape to find the perfect pair of glasses, it’s a great idea to consult with your optician for their expert opinion. For instance, if you have a high prescription power, they will advise you to go for plastic or acetate frames, as they can conceal the thickness of your glasses lenses.

Find a wide collection of prescription glasses at Feel Good Contacts at up to 70% off and order your favourite pairs by entering your prescription easily.