How to Read Your Prescription
Your prescription contains several key values that we need to make your lenses correctly. This guide explains each field so you can confidently enter your prescription when ordering.
If you find the manual entry process confusing, don't worry — you can simply upload a photo of your prescription instead, and our optical team will handle the rest.
What Is SPH (Sphere)?
SPH, or Sphere, indicates the lens power needed to correct your vision. It is measured in diopters (D):
- A minus sign (−) means you are nearsighted (myopic) — you see well up close but have difficulty with distance vision.
- A plus sign (+) means you are farsighted (hyperopic) — you see well at distance but have difficulty up close.
- Example: −2.00 means mild nearsightedness; +3.50 means moderate farsightedness.
SPH is required for each eye (OD = right eye, OS = left eye).
What Is CYL (Cylinder)?
CYL, or Cylinder, measures the amount of astigmatism correction needed. Astigmatism is a common condition where the cornea is slightly irregularly shaped, causing blurred or distorted vision at all distances:
- CYL values are typically between 0.00 and −4.00.
- If your prescription does not show a CYL value, you do not have astigmatism correction. Leave this field blank.
- CYL always appears with an Axis value.
What Is Axis?
Axis describes the orientation of the astigmatism correction, measured in degrees from 1 to 180:
- Axis is only required if you have a CYL value.
- Example: Axis 180 means the correction is oriented horizontally; Axis 90 means vertical orientation.
What Is PD (Pupillary Distance)?
PD is the distance between the centers of your pupils, measured in millimeters. This is a crucial measurement because it ensures your lenses are correctly aligned with your eyes:
- Single PD: One number (e.g., 63 mm) — the distance between both pupils.
- Dual PD: Two numbers (e.g., 32/31) — the distance from the center of your nose bridge to each pupil.
Your PD may or may not be on your prescription. If it's not listed, you can measure it yourself:
- Stand in front of a mirror with a millimeter ruler.
- Close your right eye and align the ruler's 0 mm mark with the center of your left pupil.
- Close your left eye and open your right eye. Read the millimeter mark that aligns with the center of your right pupil.
- That number is your single PD. Repeat 2-3 times for accuracy.
Note: This self-measurement method provides an estimate. For the most accurate measurement, ask your eye doctor to include PD on your prescription.
What Is ADD (Addition)?
ADD is the additional magnifying power applied to the bottom portion of progressive or bifocal lenses for near vision:
- ADD values are typically between +0.75 and +3.00.
- Only required for progressive or reading lenses.
- If you're ordering single vision distance lenses, you do not need ADD.
Progressive lens orders will be reviewed by our optical team before production. We may contact you to confirm fitting height or other measurements for optimal lens performance.
Lens Index Guide
Lens index refers to how efficiently a lens material bends light. A higher index means the lens can be thinner and lighter while providing the same prescription power. This is especially important for stronger prescriptions.
| Index | Name | Best For | Thickness |
|---|
| 1.56 | Standard | Mild prescriptions (up to ±2.00) | Standard thickness |
| 1.61 | Thin | Moderate prescriptions (up to ±4.00) | ~20% thinner than 1.56 |
| 1.67 | Ultra Thin | Stronger prescriptions (up to ±6.00) | ~35% thinner than 1.56 |
| 1.74 | Super Thin | Very strong prescriptions (over ±6.00) | ~50% thinner than 1.56 |
Progressive Lens Guide
Progressive lenses provide a seamless transition from distance vision (top of the lens) to intermediate vision (middle) to near vision (bottom). Unlike bifocals, there is no visible line separating the zones.
- Who are they for? People over 40 who need correction for both distance and near vision, or anyone who wants one pair of glasses for all distances.
- What to expect: There is a brief adaptation period of a few days as your eyes learn to use the different zones of the lens. Most people adjust quickly.
- Requirements: You need SPH, CYL (if applicable), Axis (if applicable), ADD, and PD for each eye.
Photochromic Lens Guide
Photochromic lenses contain molecules that react to ultraviolet (UV) light. They are clear indoors and automatically darken when exposed to sunlight:
- Transition speed: Lenses begin darkening within 30 seconds of UV exposure and return to clear within a few minutes after going indoors.
- Color options: Available in grey (natural color perception) and brown (enhanced contrast, popular for driving).
- Compatibility: Can be combined with single vision or progressive prescriptions and most lens indexes.
Blue Light Lens Guide
Blue light blocking lenses filter a portion of the high-energy visible (HEV) blue light emitted by digital screens, LED lighting, and the sun:
- Benefits: May reduce digital eye strain, improve sleep quality when using screens in the evening, and reduce glare.
- Who should consider it: Office workers, students, gamers, and anyone who spends 4+ hours per day looking at digital screens.
- Appearance: Lenses have a subtle blue-purple reflection when viewed from certain angles but appear mostly clear.