A progressive lens prescription lists distance power, near add, and alignment notes, giving you the pieces to read every line.
Eyeglass paperwork can look like a wall of codes. This guide breaks those codes into plain words and shows how each number maps to what you see through no-line multifocals. You’ll learn what SPH, CYL, Axis, ADD, Prism, and PD mean, how they interact in a multifocal design, and how to check that the form has what a lab needs.
The Fast Way To Decode Your Rx
Every script follows a common layout. Read across the row for each eye. Then apply the near add for close work. Use this quick map while you read.
| Field | What It Means | Where You’ll See It |
|---|---|---|
| OD / OS / OU | Right eye, left eye, both eyes | Row labels on the form |
| SPH | Main distance power in diopters; minus for nearsight, plus for farsight | Distance column for each eye |
| CYL | Astigmatism amount in diopters | Beside SPH for each eye |
| Axis | Astigmatism angle from 1–180 | Beside CYL |
| ADD | Extra power for the near and mid zones | One value used for both eyes |
| Prism / Base | Alignment correction; base up/down/in/out | Separate column or notes |
| PD | Pupil spacing in mm; monocular or binocular | Dispensing data; often in notes |
| Seg / Fit Height | Vertical position from pupil to lens reference line | Measured on your chosen frame |
Reading A Progressive Lens Rx: Symbols And Layout
Forms vary by clinic, yet the core fields match across providers. SPH lists the core distance power. CYL and Axis set astigmatism power and angle. ADD stacks near power onto the distance values in the lower zones. Prism shows when the eyes need alignment help. PD and fitting height tell the lab where to place the viewing zones so each area lines up with your gaze.
SPH: Distance Power
SPH appears in 0.25 steps. A minus sign marks nearsight. A plus sign marks farsight. Bigger absolute numbers bend light more. In multifocals, the top of the lens uses this power; lower zones blend toward near with the add value.
CYL And Axis: Astigmatism
CYL adds targeted power to offset corneal shape. Axis points to the meridian angle for that power. If CYL is blank, there’s no astigmatism entry for that eye. Axis only appears when CYL is present.
ADD: Near Power For The Reading Zone
ADD is a plus number such as +1.50 or +2.25. It shifts the image at close range while the top of the lens stays set for distance. The corridor blends from distance into midrange and near using this add value, giving you a smooth transition without lines.
Prism And Base Direction
Prism is written with a value and base direction: BU (base up), BD (base down), BI (base in), BO (base out). Small values fine-tune image alignment. Entries may sit on one or both eyes and can mirror one another.
PD: Pupil Spacing
PD can be one number (binocular) or two numbers (monocular). Monocular PD lists right then left, such as 31/32. Labs use PD to center optics, set the near inset, and keep the corridor aligned with your visual axes.
Fitting Height For Progressives
This height is taken with the chosen frame on your face. The mark aligns with your pupil, not the frame midline. Different frames change this number, which is why it’s recorded during dispensing rather than during the exam.
Step-By-Step Walkthrough With A Sample Script
Work through one set to see how each part plays out in daily vision. Say the right eye shows −2.00 SPH, −0.75 CYL, Axis 170; the left shows −1.50 SPH, −0.50 CYL, Axis 005; ADD +2.00; PD 62 (or monocular 31/31); no prism.
What Those Lines Tell You
- Distance focus: Modest minus power both sides. Distance blur was the main issue.
- Astigmatism: Small CYL entries sharpen detail; axes sit near the 0/180 range.
- Near work: +2.00 add creates a strong reading spot plus a helpful mid band.
- PD: Either one number for both eyes or split numbers for each eye; both work for labs.
- Prism: None listed, so base directions stay blank.
How A Lab Uses It
The lab maps the corridor with your add, sets the inset from PD, and positions the fitting cross at your recorded height. The finished lens places distance at the top, screen range through the middle, and reading near the bottom. Good placement keeps your eyes in the right zone with natural head posture.
Common Abbreviations And Latin Shortcuts
Clinics mix plain labels with Latin. You may see OD (right), OS (left), and OU (both). Some forms swap in “R” and “L.” Plano or “PL” means no spherical power. DS can mean “sphere only” where CYL is blank. NV adds a near-vision tag. BAL can signal a match for lens thickness when a value is missing. These trims keep the form compact without losing meaning.
Rules And References That Keep Terms Consistent
Plain terms on a script line up with clinical education and standards. The American Academy of Ophthalmology lays out the basics of SPH, CYL, Axis, and ADD in its guide to prescription terms. For PD, the College of Optometrists explains that this is a dispensing measure rather than a clinical test value, which is why it may appear outside the main lines on the form; see their note on pupillary distance.
Progressive-Only Details That Don’t Sit On The Paper
A lot of multifocal setup happens outside the exam record. Two people can share the same numbers yet need very different layouts due to frame shape, pantoscopic tilt, vertex distance, and reading posture. These factors drive corridor length, near zone size, and inset. The choices are made during dispensing after you pick a frame, often with digital tools or manual marks set while the frame rests on your face.
Corridor Length And Design Choice
Short frames call for a short corridor so the near zone sits high enough to use without chin-to-chest posture. Tall frames allow a longer blend that widens the midrange. Your day steers the choice: hours on a laptop, road time, studio tasks, or shop work can push the design one way or the other.
Material And Coatings
Lens index affects weight and thickness. Coatings help with scratch resistance and glare control. Tints adjust comfort in bright light. None of these change the numbers on the script, yet each one changes how the lens feels through a full day.
Frame Fit And Pantoscopic Tilt
Multifocals like a small forward tilt. Too flat and the near zone can sit low in real use. A quick nose-pad move or a gentle arm bend can fix alignment without re-making lenses.
Quality Checks When You Pick Up New Glasses
Use this short list at the counter. It saves return trips and helps the lab spot a miss early.
| Check | What To Look For | Quick Fix |
|---|---|---|
| Reading Spot | Words pop at a chin-down gaze about 12–16 inches | Raise or lower pads; verify fitting height |
| Screen Range | Text clears in the center band at arm’s length | Adjust tilt; check corridor choice |
| Distance | Street signs look crisp with a level gaze | Re-check SPH/CYL/Axis match to the form |
| Swim Effect | Edges feel wavy when you move your head | Refit frame; confirm PD and inset |
| Headaches | Strain after short use | Check prism entry and base directions |
| Nose Pressure | Red marks or slipping | Pad swap or arm bend |
Method: Read Your Lines In Order
- Start with OD and OS so each eye’s row stays straight.
- Note SPH values. Minus points to nearsight; plus points to farsight.
- Check for CYL and Axis. If CYL is blank, skip Axis.
- Find the single ADD value. That fuels the near and mid zones.
- Look for Prism and base directions when present.
- Record PD and whether it’s one number or split numbers.
- If you’ve chosen a frame, add the measured fitting height.
- Take a clear photo of the form and keep it on your phone.
What Each Number Means In Daily Use
Small changes matter. A 0.25 step can shift fine detail with close work. High adds make near text pop yet can shorten depth at hand range; a small add gives more range. Extra minus sharpens road signs yet can tire your eyes at a monitor. The right balance reflects your real day: driving, laptop hours, reading time, and hobbies.
When To Call The Clinic Or Shop
Reach out if you can’t find a clear spot for reading after pad tweaks, if distant signs stay soft, or if headaches linger past a week of steady wear. Bring the frames, the form, and your work distances. Small frame moves and quick lens checks solve many snags.
Sample Sets You Can Practice On
Mild Nearsight With Mid Add
OD: −1.25 SPH, −0.50 CYL, Axis 180; OS: −1.00 SPH, Plano; ADD +1.50; PD 62. Expect easy road vision and a comfy reading spot for paperbacks.
Post-Cataract Mixed Powers
OD: Plano, −1.00 CYL, Axis 090; OS: +0.50 SPH; ADD +2.25; PD 60 (30/30). Distance stays sharp with a small astigmatism fix on the right; a strong near zone helps with phone text.
Higher Astigmatism, Strong Add
OD: −3.00 SPH, −2.00 CYL, Axis 030; OS: −2.50 SPH, −1.75 CYL, Axis 150; ADD +2.50; PD 64. Expect crisp near text with a narrower sweet spot side-to-side.
Checklist Before You Order Online
- Clear photo or scan of the form
- SPH, CYL, Axis present for each eye
- Single ADD entry
- Prism data if listed
- PD as one number or split
- Chosen frame size and bridge that sit well on your nose
- Estimated fitting height taken with the frame on your face
Final Tips For Smooth Adaption
Point your nose at what you want to see, then move eyes. Drop your chin for reading. Keep screens a touch under arm’s length. Give the setup a few days of steady wear. Quick bench tweaks by the shop can turn a near miss into a win.