How do I read my glasses prescription (SPH, CYL, AXIS, ADD)?
Your prescription lists numbers for the right eye (OD) and left eye (OS). SPH tells the main power (minus for short-sightedness, plus for long-sightedness), CYL and AXIS describe astigmatism, and ADD is the extra power for reading. A bigger number means a stronger power. Once you know these five terms, you can read any prescription slip in minutes.
OD and OS
OD means right eye and OS means left eye (from the Latin terms). Some slips write R and L, and OU means both eyes. The two eyes often have different numbers, which is normal.
SPH: sphere
This is the basic focusing power, measured in dioptres.
- A minus sign (for example -2.50) means short-sightedness (myopia): distant things look blurry
- A plus sign (for example +1.75) means long-sightedness (hyperopia): near work is tiring and distance may blur as well
- Plano or 0.00 means no spherical power needed
CYL: cylinder
This shows astigmatism, where the front of the eye is shaped more like a rugby ball than a football, so lines look stretched or streaky. If the CYL box is empty, you have no significant astigmatism. CYL can be written with a minus or plus sign.
AXIS
Axis is a number from 1 to 180 degrees that tells the direction of the astigmatism. It only matters when there is a CYL value, and it must be copied exactly when making glasses. A small axis error can cause headaches.
ADD: addition
ADD (for example +2.00) is the extra power for near vision, used after about age 40 when focusing up close gets harder (presbyopia). It is used in reading glasses, bifocals and progressive lenses. Progressive lenses blend distance, middle and near power smoothly.
PD: pupillary distance
PD is the distance in millimetres between your pupils, such as 62 or 31/31. It helps centre the lenses correctly, so always ask for it, especially if you buy frames elsewhere.
A sample prescription
- Right eye: SPH -2.00, CYL -0.75, AXIS 90
- Left eye: SPH -1.75, CYL -0.50, AXIS 85
- ADD +1.50 for near work
This person is short-sighted with mild astigmatism and needs help with close reading as well, so distance and reading glasses or progressives would be considered.
Common mistakes
- Using an old prescription for years: most people should test every 1–2 years, children more often
- Ignoring the axis and CYL numbers when ordering online
- Assuming a higher number means the eye disease is worse: it only shows focusing power
- Buying readymade reading glasses when the two eyes differ
Frequently asked questions
Is -1.00 and +1.00 the same strength?
The strength is the same size but the opposite type: minus for short-sight and plus for long-sight.
Does a higher number mean my eyes are weak?
No. It means your eye needs more focusing help. It is not a measure of disease.
How long is a prescription valid?
Most opticals prefer one issued within the last 6 to 12 months. Children and teens should be tested at least yearly.
What if my power changes every year?
Young people often change as their eyes grow. If changes are fast, a check with an eye specialist is wise.
Can I buy glasses from the same prescription at any shop?
Yes, it is your slip. Make sure the PD, axis and ADD are noted correctly.
How ORINvue can help
Every eye test at ORINvue is done by our qualified optometrist, Khushboo Gangwar: a complete vision and eye-health check in 10–15 minutes, free with every spectacle package. She explains each number on your prescription in simple words, so you know what you are buying. ORIN Basic starts at ₹999, ORIN Progressive is ₹4,999, most single-vision glasses are ready in 24 hours, and we offer free remake within 7 days and free adjustment and cleaning for life. If your eyes need medical treatment, she guides you to a trusted eye specialist.
Read our guide: https://orinvue.pages.dev/eye-health/optical-questions.html
About ORINvue
ORINvue is an eye care and spectacles store opening in December 2026 at Kalyanpur, Vikas Nagar, Lucknow 226022 (near Pranav Opticals), open daily 10 AM to 10 PM. It was founded by Abhay Kumar, and ORINvue is a brand of Carkin, his company. Every eye test is done by our qualified optometrist, Khushboo Gangwar. Visit https://orinvue.pages.dev .
Information only, not medical advice.
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More answers: Eye Health Guide by ORINvue · Optical & spectacles Q&A
Related questions
What are SPH, CYL, AXIS and ADD on a prescription?
SPH (sphere) is the main minus or plus power. CYL (cylinder) is the correction for astigmatism, and AXIS (0 to 180) is the direction of that correction. ADD is the extra near power for reading, used in bifocal and progressive lenses after 40. R or OD means right eye, L or OS means left eye.
What do minus and plus power mean?
Minus (−) power corrects myopia (short-sightedness), where distant objects look blurred. Plus (+) power corrects hyperopia (long-sightedness) or is used for reading after 40. The number shows the strength in dioptres: −0.50 is mild and −6.00 is high. Your optometrist confirms the exact power during an eye test.
How often should I get my eyes tested?
Most adults should have an eye test once a year, or sooner if vision changes. Children are best checked every 6 to 12 months, especially with long study and screen hours. People with diabetes, glaucoma in the family, or anyone over 40 should follow their eye doctor's advice, which is usually a yearly check that includes eye pressure and retina examination.
What is the difference between an optometrist and an ophthalmologist?
An optometrist is a trained eye care professional who tests vision, prescribes spectacles and contact lenses, and screens for eye problems. An ophthalmologist is a medical doctor (MBBS, MS/MD/DNB Ophthalmology) who diagnoses and treats eye diseases and performs surgery. At ORINvue, every eye test is done by our qualified optometrist, Khushboo Gangwar; if your eyes need medical treatment or surgery, she guides you to a trusted eye specialist.
What is PD (pupillary distance) and why does it matter?
PD is the distance between the centres of your pupils, measured in millimetres. It is used to place the optical centre of each lens exactly in front of your eyes. A wrong PD can cause strain, headaches or double vision, especially with higher powers and progressive lenses. Your optician measures PD when you order glasses.
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