How to Read an Eye Prescription
Table of Contents
Introduction
Understanding the Different Parts of an Eye
Prescription
The
Sphere Measurement
The
Cylinder Measurement
The
Axis Measurement
The
Add Power
The
Pupillary Distance (PD)
Interpreting Single Vision Prescriptions
Sphere-Only
Single Vision Prescriptions
Combined
Sphere and Cylinder Single Vision Prescriptions
Decoding Multifocal Eyeglass Prescriptions
Reading
Bifocal Prescriptions
Understanding
Trifocal Prescriptions
Interpreting
Progressive Lens Prescriptions
The Meaning of Abbreviations on Eye
Prescriptions
Common
Ophthalmic Abbreviations
Abbreviations for the Eyes
Lens
Material and Type Abbreviations
Getting the Most Out of Your Eye Exam
Preparing
a List of Questions Before Your Appointment
Clearly
Communicating Any Vision Problems You're Experiencing
Discussing
Your Overall Eye Health with Your Doctor
Caring for Your Prescription Lenses and Frames
Cleaning
Different Lens Materials
Ensuring
Proper Frame Size and Fit
Regular
Cleaning and Maintenance
Eye Exams and Prescriptions for Children
Preschool
Vision Screenings
Comprehensive
Eye Exams for School-Age Children
Recognizing
Signs of Potential Vision Issues in Kids
Conclusion
Frequently Asked Questions about Eye
Prescriptions
Introduction
Trying to interpret all the
numbers, abbreviations, and terminology on your eye prescription can feel
overwhelming. 😵 With so many variables like spheres,
cylinders, axes, adds, and more, eye prescriptions can look like they're
written in a foreign language! However, unlocking the mystery of your
prescription doesn't have to be a stressful or frustrating process.
By learning the meaning of the
different sections on your prescription, you'll be able to understand your
current corrective needs and better communicate with your eye doctor about your
vision care. Whether you wear eyeglasses, contacts, or both, comprehending your
prescription is key to getting the clearest sight possible.🤓
This comprehensive guide will
teach you step-by-step how to read and decipher the various components of your
prescription. We'll also cover tips for making the most of your eye exam,
properly caring for prescribed lenses and frames, kids' prescriptions, and
frequently asked questions. Let's get started demystifying eye prescriptions!👓
Understanding the Different Parts of
an Eye Prescription
At first glance, an eye
prescription may look like an unintelligible combination of numbers, fractions,
and abbreviations. However, each section provides important specifics that your
eye doctor uses to create lenses or contacts that correctly address your visual
needs. Let's break down the key elements:
The Sphere Measurement
The sphere prescription is the
part that indicates the power needed to correct refractive errors like
nearsightedness and farsightedness. The sphere is measured in diopters, which
are the units used to quantify the optical power of corrective lenses.
If the sphere power is positive,
like +1.50, this signifies that the patient is farsighted. Positive sphere
numbers mean the refractive error causes light rays to focus behind the retina
instead of directly on it, making distant vision blurry. The +1.50 diopter
sphere corrects this by converging the light properly onto the retina to
provide clear faraway sight.
Conversely, a negative sphere
measurement like -2.25 indicates the patient is nearsighted.🤓
The negative value means light is bent too much and focuses in front of the
retina rather than directly on it when looking far away. The -2.25 diopter
sphere helps correct this excessive refraction by diverging the rays so they
land correctly on the retina for crisp distant vision.
So in short, positive sphere
equals farsightedness, while negative means nearsightedness. The higher the
number, the stronger the prescription required, whether plus or minus.
The Cylinder Measurement
The cylinder section of the
prescription specifies the amount of correction needed for astigmatism.
Astigmatism results from an irregularly shaped cornea or lens that prevents
light from focusing clearly on the retina. This causes blurred or distorted
vision at all distances.
Just like the sphere, the
cylinder is measured in diopters to indicate the strength of correction
necessary to compensate for the irregular astigmatic focusing. For example, a
cylinder of -1.75 means that 1.75 diopters of astigmatic adjustment is required
for optimal visual clarity.
The cylinder power typically
remains the same between a patient's two eyes. If you have -1.25 cylinders in
both your right and left prescriptions, this means you have 1.25 diopters of
astigmatism in both eyes. The cylinder works together with the sphere value to
correct nearsightedness, farsightedness, and astigmatism in combination.
The Axis Measurement
While the cylinder power
specifies the amount of correction needed for astigmatism, the axis provides
the orientation of the cylinder correction. The axis is measured in degrees on
a scale from 1 to 180.
Your eye doctor carefully
determines the specific axis angle that will properly realign your astigmatic
focusing error. Place the cylinder at the wrong angle, and the prescription
will distort rather than sharpen your vision!
So if your prescription reads
-1.50 cylinder axis 155, the 155 tells your eye care provider to position the
astigmatic correction at 155° to correctly compensate for how your eye
mis-focuses light due to your particular astigmatism.
The Add Power
For prescriptions that include
bifocals, trifocals, progressive lenses, or reading glasses, you will also see
an "add" measurement. The add indicates the amount of magnification
you need for comfortable near and intermediate vision.
For example, an add of +1.75
means you need 1.75 extra diopters of focusing power for reading or computer
work to see clearly at close range. This value gets added to the distance
sphere prescription when making the bottom portion of bifocals or trifocals, or
gradually blended in for progressives.
As we age, our eyes' lenses lose
flexibility, making it harder to focus up close. The add power helps compensate
for this loss of near focusing ability. The higher the add number, the stronger
the magnification you need for near tasks.
The Pupillary Distance (PD)
The final key measurement in your
prescription is your pupillary distance, or PD. This refers to the distance in
millimeters between the pupils in each of your eyes.
A PD of 32 means you have 32mm
from the pupil in your left eye to the pupil in your right eye. Measuring PD
allows optimal positioning of the optical centers of your lenses directly in
front of your pupils. This provides the clearest vision possible through the
glasses or contacts.
Make sure your PD is included on
your prescription, as it's essential for proper frame fitting and lens
manufacturing.👓 Knowing your PD also allows you to
accurately order eyeglasses online after getting your prescription.
Now that you know what all those
numbers and abbreviations mean, let's look at some examples of single vision
and multifocal prescriptions...
Interpreting Single Vision
Prescriptions
Single vision prescriptions are
for correcting distance or near sight in just one field of vision.
Prescriptions can get quite simple or more complex, depending on your visual
needs.
Sphere-Only Single Vision
Prescriptions
The most straightforward eyeglass
or contact lens prescription will only have a sphere value, typically the same
for both eyes. For example:
- OD (Right Eye): -2.00
- OS (Left Eye): -2.00
This means both eyes have -2.00
diopters of nearsightedness. The -2.00 sphere will compensate for the excessive
focusing power to enable clear distant vision.
A sphere-only prescription does
not necessarily mean you have perfect vision - it just indicates you have no
astigmatism or need for reading magnification that would require a cylinder or
add.
Combined Sphere and Cylinder Single
Vision Prescriptions
When astigmatism is present, the
prescription gains cylinder and axis components. Here is an example:
- OD (Right Eye): -2.50 -1.25 x
180
- OS (Left Eye): -3.00 -1.25 x
180
For the right eye, the -2.50
sphere corrects nearsightedness, while the -1.25 cylinder at axis 180 provides
the precise orientation needed to compensate for astigmatism.
The left eye has -3.00 sphere
with the same -1.25 cylinder at 180°. The prescription is tailored to each
eye's specific focusing issues to allow clear uninhibited vision.
The cylinder and axis work
hand-in-hand with the sphere to correct both spherical refractive errors like
nearsightedness and astigmatism at the same time.
Decoding Multifocal Eyeglass
Prescriptions
If you need correction for both
distance and near, bifocals or progressives are often prescribed. Let's look at
some typical multifocal prescriptions:
Reading Bifocal Prescriptions
Bifocals have two distinct
viewing zones - typically distance up top and near vision in the lower portion.
Bifocal prescriptions add an "add" power like this example:
- OD: -1.50
- OS: -1.75
- Add: +1.50
Here the distance spheres of
-1.50 and -1.75 handle the farsightedness, while the +1.50 add provides the
extra near focusing power.
Your prescription may list the
add in one eye only, but both lenses ultimately have the add blended into the
lower segment.
Understanding Trifocal Prescriptions
Trifocals take it up a notch by
adding a third section for intermediate vision. This helps with computer work
at around arm's length. For example:
- OD: -2.00
- OS: -2.25
- Add: +1.25 +2.00
The distance spheres correct
nearsightedness, while the first add of +1.25 provides some extra power for
intermediate range. The +2.00 add boosts it further for reading and close
tasks.
Interpreting Progressive Lens
Prescriptions
Progressive lenses (or no-line
bifocals) have a "progressive" transition from distance correction at
the top through the intermediate zone down to near power at the bottom.
The prescription itself typically
only lists the distance sphere and add power, without specifying
"progressive." For example:
- OD: -1.75
- OS: -2.00
- Add: +1.25
This prescribes a seamless
progression from the nearsighted distance spheres through the +1.25 add for
crisp vision at all ranges.
Progressive lenses require highly
specialized manufacturing for the gradient effect, but the prescription itself
appears straightforward like a bifocal. Work with your eye doctor to determine
if progressives suit your needs and visual preferences.
Now that you know how to
interpret the numbers, let's go over some common abbreviations found on
prescriptions...
The Meaning of Abbreviations on Eye
Prescriptions
In addition to the measurements
we've discussed, you'll likely see various abbreviated terms on your
prescription. Understanding these can remove some of the cryptic mystery!
Common Ophthalmic Abbreviations
- OD = Right Eye
- OS = Left Eye
- OU = Both Eyes
- QD = Every Day
- QAM = Every Morning
- PRN = As Needed
Abbreviations for the Eyes
- OD = Right Eye
- OS = Left Eye
- OU = Both Eyes
Knowing which eye the
prescription refers to is crucial for proper administration of corrective
lenses or medications.
Lens Material and Type Abbreviations
- CR-39 = Plastic Lens
Material
- POLY = Polycarbonate Plastic
Lenses
- BI = Bifocal
- PROG = Progressive Lenses
- SPH = Sphere
- CYL = Cylinder
These abbreviations for lens
materials and types like bifocals or progressives help communicate specific
prescription instructions.
With practice, you'll start to
recognize the most common abbreviations at a glance. Don't be afraid to ask
your eye doctor to translate anything that seems confusing!
Now let's go over some tips for
making the most of your eye exam and getting the most accurate prescription...
Getting the Most Out of Your Eye
Exam
Your prescription is only as good
as the inputs provided at your eye exam. Follow these steps to be sure your
prescription optimally addresses your vision needs:
Preparing a List of Questions Before
Your Appointment
Think through any vision
problems, challenges, or concerns you've been experiencing and jot them down.
Bring the list to your appointment so you remember to tell your doctor. This
provides key insights into tweaks needed for your new prescription.
Some issues to note may include:
- Headaches or eye strain when
reading
- Blurry distance vision at night
- Problems using computer screens
for long periods
- Difficulty seeing small text on
cell phones
- Eye tiredness or irritation
Specifying when and how your
vision is lacking helps pinpoint areas for improvement. 🤓
Clearly Communicating Any Vision
Problems You're Experiencing
During your exam, explain all the
issues you recorded in detail. Your optometrist can only adjust your
prescription to fix what they know is broken!
Describe where, when, and how
your vision is bothering you. For example, "My eyes feel really tired
after using my computer for more than 30 minutes."
This provides valuable clues into
what corrections or treatment may be needed. Don't downplay or omit problems -
full information results in the best prescription.
Discussing Your Overall Eye Health
with Your Doctor
Beyond assessing your refractive
errors and vision troubles, your eye doctor also examines the health of your
eyes. Be sure to:
- Ask about the results of your
dilated retinal exam - this evaluates eye diseases
- Discuss any family history of
glaucoma, macular degeneration, etc.
- Address risk factors like high
Rx medication use, smoking, or sun exposure
- Learn when you should return for
follow-up exams
Understanding your current eye
health allows you and your doctor to make fully informed choices regarding your
vision care.
With the right prep work and open
communication, your eye exam leads to a tailored prescriptionsolving your unique
vision puzzles. Next let's review proper lens and frame care to keep your
glasses working their best!
Caring for Your Prescription Lenses
and Frames
Getting glasses or contacts
fitted with your new prescription is an exciting milestone!⚡️
Keep them functioning flawlessly with proper maintenance:
Cleaning Different Lens Materials
- Plastic CR-39 and polycarbonate
lenses can usually be cleaned with soap/water and microfiber cloths. Rinse
well.
- Glass lenses may require more
specialized cleaners to avoid coating damage.
- Follow your eye doctor's
recommendations for contact lens solutions.
Ensuring Proper Frame Size and Fit
Make sure your eyeglass frames
fit comfortably without sliding down your nose. Temple arm length should align
the lenses directly in front of your eyes. Have them adjusted at your optical
shop if needed.
Regular Cleaning and Maintenance
- Clean lenses daily with
approved cloths and cleaners.
- Avoid dropping glasses or
contacts.
- Keep contact lenses hydrated
with fresh solution.
- Don't wear contacts longer than
prescribed.
- Have prescriptions updated
yearly or as directed.
With conscientious care, your
glasses and contacts will help you see your best for years to come! 👓👀
Eye Exams and Prescriptions for
Children
Monitoring children's vision
development and refractive errors is critical for their learning and
development. Let's look at some key recommendations:
Preschool Vision Screenings
The American Optometric
Association recommends all children get an initial eye assessment between ages
3 and 5. Early screening detects problems like lazy eye or farsightedness at a
critical age for vision development.
Comprehensive Eye Exams for
School-Age Children
Once a child starts school, the
American Optometric Association advises a comprehensive exam every year or two.
Annual vision screening is crucial for identifying issues like nearsightedness
that may develop with increased near work.
Eye exams should take place at
least by age 5-6 when most kids begin reading and writing. Proper
identification and correction of vision disorders helps ensure children meet
learning milestones.
Recognizing Signs of Potential
Vision Issues in Kids
In addition to professional eye
exams, watch for possible vision problems like:
- Squinting or covering one eye
- Sitting extremely close to the
TV
- Tilting head closely to read
books
- Avoiding reading/close work
- Red or watery eyes
- Rubbing eyes excessively
- Frequent headaches or dizziness
If you notice any signs of
distress, arrange an eye exam to determine if vision correction is recommended.
Unidentified problems can hamper learning and development.
With diligent eye care, your
child's world will come into focus and they can flourish!👧🏻👦🏽
Conclusion
Reading an eye prescription
doesn't need to be a confusing or frustrating process. By learning some basic
terminology and notation, you can interpret what all those numbers and
abbreviations mean. This allows you to fully comprehend your current visual
status and needs. ✅
Understanding parts like sphere,
cylinder, axis, add, and PD enables you to communicate effectively with your
eye doctor and get lenses or contacts that precisely match your prescription.
Ask questions if any aspect is
unclear - your eye care provider wants to ensure you're educated about your
vision condition and correction.
And be sure to take steps like
preparing for your exam, detailing issues, and cleaning your lenses to get the
best vision possible. 👓 With the mysteries of
eye prescriptions decoded, you're on your way to crisp, comfortable sight!
Frequently Asked Questions about Eye
Prescriptions
Here are answers to some common
questions that often come up regarding reading and understanding
What does the cylinder part of my prescription mean?
The cylinder specifies the power
and axis of the astigmatic correction you need. It works with the sphere to
properly correct your vision.
Do I really need to know all the parts of my prescription?
While you don't need to memorize
your prescription, understanding the key components will help you communicate
with your eye doctor and get the most appropriate lenses.
What's the difference between farsighted and nearsighted prescriptions?
Farsighted prescriptions have
positive sphere powers like +2.00, while nearsighted spheres are negative like
-2.75. This indicates whether you can see far or near easier.
Why are there two sphere powers for my right and left eyes?
Most people's eyes require
slightly different prescriptions. Listing right and left powers separately
allows each eye to be corrected optimally.
What does the axis number mean in my astigmatism prescription?
The axis refers to the angle of
orientation for the astigmatic correction. It allows the right placement of
power for your particular astigmatism.
What if I can't read part of my prescription?
Don't hesitate to ask your eye
doctor to explain or translate any aspect of your prescription that is unclear.
They want you to fully understand your vision needs.
What does it mean if my prescription changes a lot between exams?
Big prescription changes may
indicate your vision has changed significantly or that you have a condition
requiring close monitoring. Discuss any major shifts with your eye doctor.
Can I order glasses online with my prescription?
You can order eyeglasses online
as long as you have your latest prescription. Be sure to double check you've
entered it accurately before ordering.
Do I need a new prescription every year?
How often you need a new
prescription depends on factors like your age and eye health. Your doctor can
advise if an annual exam is recommended for your situation.