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A quick guide to interpreting eye test results

Eye test results: If you’ve always wondered what all those […]

By Published On: 26 May 20176.7 min read

Eye test results: If you’ve always wondered what all those vision test chart results actually mean when you have your eyes tested, read on!

The Eye Practice has put together a short guide to understanding short-sightedness, long-sightedness and astigmatism from the numbers on your glasses prescription. Having your (or your child’s) eye test results explained can be very empowering.

What does your glasses prescription mean?

In simple, concise terms, your spectacle prescription is a measure of how short-sighted or long-sighted you are in each eye, as well as how much astigmatism you have and which part of your eye is more curved than the other.

Wait, what’s astigmatism again? 

This causes a lot of confusion! The cornea, or front surface of your eye, is like a clear dome allowing light entering your eye to be focused on your retina. The exact curvature of your cornea determines whether you are short-sighted or long-sighted. Short-sighted folks can see perfectly well up close, but distance is blurred. If you’re long-sighted, close work is more blurred, although distance is often (but not always) fine.  A cornea that is more curved than normal is myopic – the medical word for short-sighted. A flatter than average corner is long-sighted.

There. Easy so far.

Astigmatism is simply the difference in curvature between the steepest and flattest curves of your cornea. If you think of the front of your eye as a bit like an egg or rugby ball, one contour is more steeply curved than the other. In the eye it is very subtle, but even a small difference in curvature means you have this condition. It is perfectly normal to have a small amount in each eye. In fact, it is much rarer to have perfectly spherical eyes, with no astigmatism whatsoever.

The difference in curvature often happens naturally, due to the flexible eye’s position in a socket between your rigid brow bone and cheek bone as well as pressure from the eyelids. It gets ever so slightly compressed so it is a little curvier vertically compared to horizontally.

Now you understand astigmatism better than 9 out of 10 medical students (no kidding).

Understanding your eye test results: the numbers explained

The numbers on your spectacle prescription are shown for your right eye (indicated as RE or sometimes OD – the Latin for oculus dexter, meaning right eye) and your left eye (LE or OS – oculus sinister). Most optometrists use RE and LE but you will sometimes come across OD/OS in eye hospitals and some ophthalmologist’s practices.

If there is only one number, this means the eye is spherical (the same curve all over, like a golf ball) and has no astigmatism correction:

RE:   + 4.74DS

The unit of measurement is called the dioptre (D) and in this case, DS means dioptre sphere.

So far so good!

The plus (+) sign in front of the number means you are long-sighted. Your glasses lenses will be thicker in the centre and thinner at the edges and make things look bigger (including your eyes).

A minus sign means you are myopic (short-sighted). Your glasses lenses will be thicker at the edges and thinner in the centre and will make things look smaller (including your eyes).

The following prescription is for a short-sighted eye with no astigmatism correction:

LE:  – 7.50 DS

What about the other numbers?

Most eyes are not spherical, so the numbers need to be able to show how much more curvature is in one meridian (or contour) and where that is.

RE:  -3.00 DS / -1.00 DC x 90

In the example above we can tell that one curve of the cornea is 3 dioptres short-sighted.

RE:  -3.00 DS / -1.00 DC x 90

BUT, the other curve of the eye is an extra 1 dioptre short-sighted on top of that 3. This means the opposite contour is 4 dioptres shortsighted (the original – 3 and the extra – 1).

RE:  -3.00 DS / -1.00 DC x 90

And the last number?  This extra curvature is required at 90 degrees in order to correct the eye.  DC stands for the extra dioptres (called dioptres cyl).

What about reading vision?

Up until 45 years of age, your prescription is usually the same for all distances. (There are some exceptions to this, including children who are highly long-sighted, or myopic).

If you’re over 45 years of age, your reading prescription will be different to your distance. This is often shown as a single number (called a ‘reading add’, ‘reading addition’ or ‘near add’) beneath the other information and is always a plus (+) number:

RE: +1.75 DS
LE:  +1.75 DS

Reading Add:  +2.00 DS

In the above example, the right and left eyes are long-sighted and they also need additional reading power for close work of 2 dioptres.

If you have distance and reading glasses, the distance glasses will be +1.75 dioptres in each eye and the reading glasses will be +3.75 dioptres in each eye. If you have multifocals, the top half of the lens will be +1.75 dioptres and the bottom part (where you look through to read) will be +3.75 dioptres.

The reading add is determined by the distance you read at, so you may have a different prescription for computer work.

Are there any other numbers – what about prism glasses?

Occasionally there will be another set of numbers. This happens if the two eyes are not working properly together and causing double vision. In this case, the lens can be slightly wedge-shaped to redirect the light and line the two images back up so you can see clearly in stereo without the double vision. This wedge-shape is called a prism.  Prism is also measured in prism dioptres (denoted as the Greek letter delta – a little triangle) and prism glasses have another set of numbers on the prescription showing how much prism and whether it is needed to align the vision vertically (base up / down) or horizontally (base in / out):

RE:   +1.75 DS  1.0 ∆ Base up

LE:    +1.75 DS  1.0 ∆ Base down

So, now you know what the numbers on your prescription really mean. One last thing to keep in mind is that your optometrist may not prescribe exactly what they find. For example, if you have a very small amount of astigmatism and it has never caused you any symptoms, they may not include this correction in what they prescribe. This is standard practice and often makes it easier to adjust to your new glasses.

What about my contact lens prescription? What do the numbers mean?

Contact lens prescriptions contain information on your short-sightedness, long-sightedness and astigmatism. But they also contain a whole new set of numbers.

A typical contact lens prescription for one eye looks something like this:

RE:  8.7 / 14.00 mm / -3.00 DS 

  • The first number is the base curve of the contact lens – in other words how curved it is. While hard lenses come in many different base curves, soft disposable contact lenses often come in only one or two options, as they tend to wrap onto the eye. 
  • The second number is the diameter of the lens – measured in millimetres.
  • The last number is similar to the spherical correction in a glasses prescription. But there are a few differences!

Why is my contact lens prescription different to my glasses prescription?

If you’re wondering why your eyeglass and contact lens prescriptions are different, here’s how:

  • Small amounts of astigmatism are masked by the thickness of the contact lens and are usually incorporated into the spherical correction.
  • With higher amounts of myopia, the minus power for will be a little lower (and the plus power a little higher for longsighted people) due to the optical effect of the contact lens sitting right on the eye instead of in front of it (like in a pair of glasses).

Both of these reasons mean that your glasses script and contact lens script can look quite different.  Added to that, the base curve and diameter make your contact lens prescription specific to your individual eyes.

Having trouble getting the best glasses prescription? Come and see the experts. Call The Eye Practice on (02) 9290 1899 or make an appointment online today.



  1. Val Plant 12 June 2020 at 10:06 am - Reply

    Enjoyed every bit of your blog.Really looking forward to read more. Great.

    • Jim Kokkinakis 14 June 2020 at 3:08 pm - Reply

      Thank you Val. We devote a significant amount of time and resources to keeping our blog informative and up to date. Eyes are precious and we hope that by writing these blogs people that read them will understand that eyes are not to be taken for granted. If you have any eye topics that you would like us to write about please just ask.

  2. Jandre 26 August 2020 at 10:37 pm - Reply


    My optometrist sent the following in my report – I am looking to have spectacles made up to this script. My contact lenses (supplied by the optometrist) are both LE and RE at -1.50. Is the below result saying the same thing?

    RE -1.50

    LE -125/ -0.50 X 63

    PD 65

    • Jim Kokkinakis 22 September 2020 at 8:28 pm - Reply

      Yes it is Jandre. In glasses we are able to prescribe more accurately than soft contact lenses.

  3. Cathy 10 November 2020 at 4:00 am - Reply

    I’m a school nurse. Can you tell me what this child’s exam result is I need a 20/20 sort of result for his school record.

    OD +6.50 8.5/14.3
    OS +8.00 8.5/14.3

    ordered contact lenses to be worn at all times.

    • Jim Kokkinakis 26 November 2020 at 11:25 am - Reply

      Cathy this is a contact lens prescription. It tells me nothing about what the visual quality is like through these lenses.

  4. Nida 6 December 2020 at 12:44 am - Reply

    Hello.I am a 66 y/o Filipina woman with a reading of + 2.75 for SPH and CYD of -1.25?
    What does this mean? Salamat Po!–Ate Nida

    • Jim Kokkinakis 8 December 2020 at 11:17 am - Reply

      Hi Nida
      This prescription basically implies that your distance vision is reasonable without glasses (although not perfect), and your main problem is you have an eye condition called presbyopia, which affects us all after the age of 40. It also means that you require reading glasses for most reading tasks.

  5. Don Clyde Stafford 30 December 2020 at 1:37 pm - Reply

    Recently had cataract left eye operation, vision is excellent without glasses, reading / computer / photography unaided . With glasses exceptional , TV / long distance best I’ve had. Binocular however at 100 degrees of clear horizontal visual field, caused my driving licence to be cancelled. I am in the process of appealing the licencing decision in court. I wonder what the general opinion and experience of binocular test failure might be. Note my right eye is a non event. Thank you DonS

    • Jim Kokkinakis 11 February 2021 at 2:41 pm - Reply

      Don in Australia you need at least 110 degrees of peripheral vision. When you say your right eye is a non event, does that mean it is blind?

  6. Carmel Bogdan 5 February 2021 at 1:43 pm - Reply

    My latest test is (left eye) sph -1.00, cyl –200 x7 (for the axis). Previous test was sph .75, cyl .2.00 x 20 (axis) how bad is this change ?

    • Jim Kokkinakis 11 February 2021 at 11:15 am - Reply

      This change is not abnormal and is not a large change at all.

      • Julie 1 August 2021 at 10:13 am - Reply

        My prescription from 2 weeks ago shows,
        R … SPH +250 CYL -0.25 AXIS 110 NADD +250

        l…. SPH +3.00 NADD+250

        And how do you measure distance between pupils.

        Thank you.

        • Jim Kokkinakis 2 October 2021 at 2:12 pm - Reply

          This type of prescription requires very careful inter pupilliary measurement. If this is measured incorrectly your are likely to suffer from eye strain and poor vision. If you are thinking of making these glasses on the internet and not having aprofessional measure this, you will waste your money.

  7. Carmel Bogdan 5 February 2021 at 1:44 pm - Reply

    So why the big change in the axis?

    • Jim Kokkinakis 11 February 2021 at 11:16 am - Reply

      a 13 degree change to the axis is not abnormal, unless you are developing a condition called keratoconus. This can be diagnosed using an instrument called a corneal topographer.

  8. sherry mainquist 31 March 2021 at 5:55 am - Reply

    I have a, +4.00 Left eye (sphere) -0.75 (Cylinder) 95.0 (Axis)
    +3.25 Right eye -0.50 65.0 but my addition is only 2.25 for right and left eye. I feel like I’m sitting on top of my pc. Can it be adjusted higher without causing harm to my eyes?

  9. Craig Roberts 9 April 2021 at 2:11 pm - Reply

    Hi there, I’m a 45 year old with slight hyperopia and have well and truly hit presbyopia. My latest eye exam has given me +2.25 diopters. At what diopter point will I start to have that noticeable ‘bug eye’ where the eyes look magnified, and are there lenses these days that can reduce/eradicate that these days?

    • Jim Kokkinakis 6 May 2021 at 10:55 am - Reply

      Craig all plus lenses will magnify the look of the eye. With the latest lens designs it normally will not be an issue until one reaches +4.00. Remember you can always choose contact lenses. Once you are 50 you also can have a procedure called refractive lensectomy, which will then put you back to just wearing simple thin reading glasses.

  10. linda boyd 15 April 2021 at 11:03 am - Reply


    • Jim Kokkinakis 6 May 2021 at 10:51 am - Reply

      I am sorry you have to go through this. The only thing you can do, is very strict management of your glucose levels. Luckily we have these injections now, which are far better than anything we have had in the past.

  11. Hansel 13 May 2021 at 9:56 pm - Reply

    Hi there,

    I’ve just had my first eye and have been left confused. Can you please interpret the reasons for me. I’m a 28yo Malaysian male,
    R -1.25 -1.25 110.0
    L -0.25 -0.25 80.0

    Should I be wearing glasses all the time now?

    • Jim Kokkinakis 8 July 2021 at 4:50 pm - Reply

      This prescription will improve your distance vision somewhat. It is not necessary to wear the glasses all the time.

  12. Wendy 16 July 2021 at 2:56 am - Reply

    Thank you for a very informative website! I am 70yo and after LASIK have been slightly myopic (20/25 in left eye and 20/35 in right) and using 2.0 readers for close work. Just had my annual exam and am going to try prescription glasses with progressive bifocals. My prescription is +1.0 for right eye and -.50 for left, with an “Add” of +2.5. Does this make sense? I understand the -.5 but don’t understand why the other eye is +1.0 when I am slightly nearsighted. Thank you!

    • Jim Kokkinakis 2 October 2021 at 2:41 pm - Reply

      Thank you for the positive feedback Wendy.
      The +1.00 means you are long sighted in the right eye. This means your vision is quite poor reading, when compared to the left (with no glasses on). At the age of 70, this is quite old to have LASIK, unless you had it 20 years ago. These days anyone over 50 should have lens replacement instead of LASIK. Why? We can leave that for another day, as you can see I am behind on answering the great questions.

  13. Ashley Forrest 16 July 2021 at 11:03 am - Reply

    My daughter got these results from a school exam, but I don’t know if she should were her glasses all time.
    -1.75 -1.00 @90° -2.25
    -1.7.5 -0.75 @90° -2.25

    • Jim Kokkinakis 2 October 2021 at 2:46 pm - Reply

      This is a very unorthodox way of issuing a prescription (assuming you have copied it correctly}. Either way this type of prescription needs to be worn all waking hours. She has a condition called myopia, with a little bit of astigmatism. Depending on her age, I would also see an optometrist that specialises in myopia control, as she is at risk of progression, without appropriate advice and treatment. See my information on myopia:

  14. Dhel 2 August 2021 at 1:53 pm - Reply

    Hi can you please interpret this for me
    R +25 SPHR ADD+175 MPD 32
    L PL ADD 175?MPD 33

    For my niece
    R -25 SPHR MPD 30
    L -25 SPHR MPD 31.5
    Do we need to wear glasses always? Thank you.

    • Jim Kokkinakis 2 October 2021 at 2:09 pm - Reply

      You need glasses to read. Your distance vision should be satisfactory.
      Your neice would hardly ever need to wear these glasses. They would only make her distance ever so slightly better, if at all.

  15. Nizar 2 August 2021 at 7:07 pm - Reply

    My OPHTHALMOLOGIST gave me the following numbers for my glasses.
    RE: -0.50×90 6/6
    LE: -1-0x90 6/6
    Add BE +2.50

    What does above mean in layman’s words ?

    • Jim Kokkinakis 2 October 2021 at 2:08 pm - Reply

      This means you have very slight astigmatism and also require some help to read. On average this prescription would make you over 50 years of age. Remember I said on average. If you are under 50 then the reading glasses are only useful to read very small things at around 30 cm. Trying to read a computer at 70cm would very very difficult.

  16. Mai 15 August 2021 at 3:02 am - Reply

    Hi Jim. I was prescribed by
    Right -0.75 -1.25 x 100, 6/7.5+2 add 1.50, N4 and
    Left -1.00 -1.00 x 65, 6/6-2 add 1.50, N4
    Pupilliary distance: 60mm and near: 58mm

    I wonder what those mean but I have troubled seeing clearly 10ft away from me and seeing not a sharp object but it seemed fine when the weather is clear or sunny day. I am 42 year old. Is this prescription a reason to worry?

    • Jim Kokkinakis 2 October 2021 at 2:02 pm - Reply

      Mai you prescription is not complicated. I have copied it into my answer and I will break it down:
      Right -0.75(this means you are slightly nearsighted) -1.25 x 100 (this means you are slightly nearsighted), 6/7.5+2 (this means your distance vision is not perfect) add 1.50 (this means you needs some extra magnification to read, this can happen any time after 40), N4 (this means that with the extra magnification your reading visin is perfect) and
      Left -1.00 -1.00 x 65, 6/6-2 add 1.50, N4 (the answers for the left are the same as the right, except that your distance vision with glasses although not perfect is better than the right)

      Pupilliary distance: 60mm and near: 58mm

      If you have never had glasses before and even with the glasses you feel your visino in ceratin circumstances is not great, then a second opinion is a good idea.

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