Computer Glasses PD: Optimizing Your Screen Time Vision

PD for Computer Glasses

Last updated: January 2025 | Reading time: 9 minutes

You spend 8+ hours a day staring at screens. Your eyes hurt by 5 PM. You've tried adjusting brightness, taking breaks, using eye drops. Maybe it's time for computer glasses.

But here's what most people miss: computer glasses need slightly different specifications than regular glasses—including PD adjustments. Getting this right can make the difference between glasses that relieve digital eye strain and glasses that don't really help.

Why Computer Distance Is Different

Computer screens typically sit at "intermediate" distance—farther than reading material but closer than true distance vision. For most people, this means:

Reading distance: 30-40cm (12-16 inches)
Computer distance: 50-70cm (20-28 inches)
Distance vision: 6+ meters (20+ feet)

Your eyes converge (turn inward) more for closer targets. Computer distance requires less convergence than reading but more than distance viewing. This affects the ideal optical center positioning.

Calculating Computer PD

The convergence effect on PD is proportional to working distance:

| Working Distance | PD Reduction from Distance PD | |------------------|------------------------------| | 40cm (reading) | ~3-4mm | | 50cm (close monitor) | ~2.5mm | | 60cm (standard monitor) | ~2mm | | 70cm (extended arm) | ~1.5mm | | 80cm+ (large screen) | ~1mm |

Example: Your distance PD is 64mm. For a monitor at 60cm, your computer PD is approximately 62mm.

Measuring Your Actual Computer Distance

Before calculating computer PD, know your actual working distance:

Sit at your computer in your normal posture
Have someone measure from your eyes to the center of your screen
Or hold a measuring tape from your cheekbone to the screen yourself

Most people are surprised to find their distance differs from what they assumed. Don't guess—measure.

Types of Computer Glasses and Their PD Needs

Single Vision Computer Glasses

These provide a single prescription power optimized for your screen distance. They're the simplest solution.

PD requirement: Use your computer-distance PD (distance PD minus 1.5-2.5mm depending on your setup).

"Office" or Occupational Progressive Lenses

These are modified progressives designed for indoor work. They typically cover:

Upper portion: intermediate distance (screens)
Lower portion: near distance (desk documents)

PD requirement: Usually ordered with distance PD; the lab applies appropriate inset for the near zone.

Blue Light Blocking Glasses (Non-Prescription)

These don't correct vision—they just filter blue light. They're often sold with fixed PD around 62-64mm.

If you're buying non-prescription blue light glasses, PD matters less since there's no optical correction to position. The "lenses" are essentially flat with coating.

Prescription Blue Light Glasses

If your blue light glasses have prescription, all the same PD considerations apply as any other prescription glasses. The blue light filtering is just an added coating.

The Desk Setup Factor

Your physical workspace affects ideal computer glasses specifications:

Single Monitor Setup

Straightforward—optimize for your screen distance. Most people position single monitors at 50-65cm.

Dual Monitor Setup

With two monitors, you may look left and right frequently. Standard computer glasses work, but consider:

Your PD is the same regardless of where you look horizontally
Very narrow corridors (in office progressives) might feel limiting
Ensure frame width allows comfortable peripheral viewing

Monitor + Document Workflow

If you constantly reference paper documents while using the computer, you're switching between two distances:

Screen: 50-70cm
Documents: 30-40cm

Office progressives handle this well. Single vision computer glasses optimized only for screen distance will be blurry for paper documents.

Laptop vs. Desktop

Laptop screens are typically closer than desktop monitors (45-55cm vs. 55-70cm) because the keyboard forces your position. Calculate computer PD based on your actual laptop distance.

Symptoms of Wrong Computer PD

If your computer glasses' PD is off, you might experience:

Eye Fatigue Acceleration

Eyes tire faster than they should because of constant prismatic compensation. The whole point of computer glasses is reducing strain—wrong PD undermines that goal.

Neck and Shoulder Tension

You might unconsciously adjust your posture to find the clearest vision through your lenses. This manifests as neck strain, shoulder tension, and awkward sitting positions.

Narrow "Sweet Spot"

With incorrect PD, the comfortable viewing zone feels cramped. You find yourself moving your head more than your eyes to keep images clear.

End-of-Day Headaches

The classic symptom—headaches that build throughout the workday and improve when you stop using screens (and remove your glasses).

Ordering Computer Glasses Online

If you're ordering computer glasses online:

Specify the Purpose

If the retailer offers specific "computer glasses" options, use them. These products may have different default assumptions than general-purpose glasses.

Adjust PD Yourself If Needed

If the order form just asks for "PD" without context, enter your calculated computer PD. The form doesn't know these glasses are for computer use unless you tell it (or enter the appropriate PD).

Consider Lens Design

Single vision lenses are straightforward. Office progressives require more careful specification—segment heights, corridor lengths, and the specific progressive design all matter.

Communicate Add Power Appropriately

For office progressives or computer-optimized multifocals, your "add power" may differ from standard reading glasses. Some computer lenses use a reduced add that's optimized for screen rather than book distance. Consult with your eye care provider about the appropriate add for computer work.

Sample Calculation

Let's walk through a complete example:

Your information:

Distance PD: 66mm (measured)
Computer screen distance: 60cm (measured)
Prescription: -2.50 sphere OU (both eyes)

For single vision computer glasses:

Computer PD = 66mm - 2mm = 64mm
Enter 64mm as your PD when ordering

For office progressive computer glasses:

Enter distance PD: 66mm
Let the lab calculate near zone inset
Specify the lens is for "office/computer" use

When to Just Use Distance PD

For some situations, the difference isn't worth worrying about:

Prescription under ±1.00 diopter: Induced prism from 2mm PD difference is minimal
Occasional computer use: If you're not spending hours at screens daily, the optimization matters less
Large screen distances (80cm+): You're approaching distance viewing anyway

The people who benefit most from computer-specific PD are those with moderate-to-strong prescriptions who spend substantial time at screens.

Testing Your Setup

Once you have computer glasses, validate they're working:

Comfort Test

Wear them for a full workday. Are your eyes more comfortable than before? Is end-of-day strain reduced?

Posture Check

Are you sitting naturally, or do you find yourself leaning forward/backward or tilting your head to see clearly?

Coverage Check

Can you see your entire screen clearly without excessive head movement? Can you see your keyboard (if needed)?

The Remove Test

After extended use, remove the glasses. If your eyes feel relieved rather than strained, the glasses weren't helping as intended.

Investment Perspective

Dedicated computer glasses are an investment in your daily comfort and long-term eye health. Getting them right includes:

Appropriate prescription for intermediate distance
Correct PD for computer working distance
Suitable lens design for your workflow
Blue light filtering if desired

Skimping on measurement accuracy (including PD) undermines the entire investment. A $200 pair of computer glasses with wrong PD may perform worse than $50 readers modified for your actual needs.

Ready to order computer glasses? Get your PD first—measure at distance with our free tool, then subtract 2mm for typical screen distance.