Understanding Your Eye Prescription

Reading your eye prescription can be confusing. This guide breaks down each component so you can understand your vision needs.

Basic Prescription Components

SPH (Sphere)

What it means: The amount of lens power needed to correct nearsightedness or farsightedness

Understanding the numbers:

• Negative numbers (-): Nearsightedness (can see close, difficulty seeing far)
• Positive numbers (+): Farsightedness (can see far, difficulty seeing close)
• Plano (0.00): No correction needed for distance/near vision

Examples:

• -2.00: Mild nearsightedness
• -5.00: Moderate nearsightedness
• +1.50: Mild farsightedness
• +3.00: Moderate farsightedness

CYL (Cylinder)

What it means: The amount of lens power needed to correct astigmatism

Understanding the numbers:

• Indicates the degree of astigmatism
• Can be positive or negative
• If blank or "DS," you don't have astigmatism

Examples:

• -0.75: Mild astigmatism
• -2.00: Moderate astigmatism
• -3.00: High astigmatism

AXIS

What it means: The orientation of astigmatism correction (in degrees)

Understanding the numbers:

• Number between 1 and 180
• Indicates the angle of astigmatism
• Only present if you have a CYL value

Examples:

• 090: Vertical astigmatism
• 180: Horizontal astigmatism
• 045: Diagonal astigmatism

ADD (Addition)

What it means: Additional magnifying power for reading (bifocals/progressives)

Understanding the numbers:

• Always positive
• Usually between +0.75 and +3.00
• Used for reading glasses, bifocals, or progressives

Examples:

• +1.00: Low reading addition
• +2.00: Medium reading addition
• +2.50: High reading addition

PD (Pupillary Distance)

What it means: Distance between your pupils (in millimeters)

Understanding the numbers:

• Usually between 54 and 74mm for adults
• Ensures lenses are centered on your eyes
• Can be single number or two numbers (one for each eye)

Examples:

• 62: Single PD measurement
• 31/31: Dual PD (31mm for each eye)

Types of Prescriptions

Single Vision

• Corrects one field of vision (distance OR near)
• Most common type
• Simple prescription

Bifocal

• Two prescription areas in one lens
• Top: Distance vision
• Bottom: Reading vision
• Visible line between areas

Progressive

• Multiple prescription areas
• Seamless transition from distance to near
• No visible lines
• More complex prescription

Reading Glasses

• Single vision for near vision only
• Positive SPH value
• ADD value may equal SPH

Reading Your Prescription

Example Prescription:

``` SPH CYL AXIS ADD OD: -2.50 -0.75 180 +2.00 OS: -2.25 -0.50 175 +2.00 PD: 62mm ```

Translation:

• OD (Right eye): -2.50 sphere, -0.75 cylinder at 180°, +2.00 add
• OS (Left eye): -2.25 sphere, -0.50 cylinder at 175°, +2.00 add
• PD: 62mm pupillary distance

Common Terms

OD (Oculus Dexter): Right eye OS (Oculus Sinister): Left eye OU (Oculus Uterque): Both eyes DS (Dioptric Sphere): No astigmatism DP (Dioptric Power): Lens power measurement

Prescription Expiration

• Most prescriptions are valid for 1-2 years
• Check expiration date on your prescription
• Regular eye exams ensure accurate prescriptions
• Updated prescriptions may be needed for vision changes

Ordering Glasses with Your Prescription

What You Need:

• Complete prescription (all values)
• PD measurement
• Frame selection
• Lens type preference

Lens Options:

• Single vision: One prescription throughout lens
• Bifocal: Two prescription areas
• Progressive: Multiple areas, seamless transition
• Reading: Near vision only

Lens Materials:

• Plastic: Lightweight, affordable
• Polycarbonate: Impact-resistant, UV protection
• High-index: Thinner for strong prescriptions
• Trivex: Impact-resistant, optical clarity

Lens Coatings:

• Anti-reflective: Reduces glare
• Scratch-resistant: Protects lenses
• UV protection: Blocks harmful rays
• Blue light filter: Reduces digital eye strain

Colored Contacts Prescription

Even non-corrective colored contacts require a prescription:

• Base curve (BC): Lens curvature
• Diameter (DIA): Lens size
• Power: Can be plano (0.00) if no correction needed

When to Get a New Prescription

• Vision changes
• Eye discomfort
• Prescription expiration
• Regular check-up (annually or biannually)
• Before buying new glasses or contacts

Tips for Accurate Prescriptions

1. Get regular eye exams: Every 1-2 years
2. Communicate with your doctor: Describe vision issues clearly
3. Test in different lighting: Ensure prescription works in all conditions
4. Ask questions: Understand your prescription fully
5. Keep copies: Store prescriptions for future reference

Common Questions

Can I use my glasses prescription for contacts? No, contact lens prescriptions are different and require additional measurements.

What if my prescription doesn't have PD? Contact your eye care professional to get your PD measurement.

Can I order glasses with an expired prescription? It's not recommended. Get an updated prescription for accurate vision correction.

Why are my eyes different? Most people have slightly different prescriptions for each eye. This is normal.

Need Help?

If you have questions about your prescription, contact our customer service team or consult your eye care professional.