When You First Get Your Glasses Prescription
You leave the eye exam holding a small sheet full of letters and numbers. Abbreviations like SPH, CYL, AXIS, ADD and PD look unfamiliar to most people. This is one of the most common questions we hear at our store in Kemalpasa. As a team that provides optical care in this part of Izmir, we wanted to read every line of your prescription together with you.
Understanding your prescription is not as hard as it seems. In a few minutes you can work out which value belongs to which eye, what the plus and minus signs mean, and how strong your correction really is. Reading this sheet is also the first step toward choosing the right lens and the right frame.
What OD, OS and R, L Mean on a Prescription
On the left side of the prescription you usually see two rows. The top row belongs to your right eye and the bottom row to your left eye. OD stands for the right eye (oculus dexter), while OS means the left eye (oculus sinister). Opticians and doctors use this layout worldwide, so your prescription reads easily anywhere else too.
Some prescriptions prefer letters instead. The letter R marks the right eye and the letter L the left eye. Each eye has its own number, and the two eyes often carry different values. This is completely normal.
On some sheets you also see distance and near headings next to the rows. These headings tell you which number applies when you look far away and which one applies up close. If you have separate numbers for distance and near, your glasses are planned around that.
What the SPH or Sphere Value Tells You
SPH is the most basic value on the prescription and it stands for sphere. This column shows the myopia or hyperopia number in your eye. The value is written in dioptres, and the sign in front of it says a lot. A dioptre is the unit that measures the focusing power of a lens.
A minus number means you have myopia. In other words you see distance as blurry and read up close more comfortably. A plus number points to hyperopia, which for many people shows up as difficulty seeing near objects. For example, minus 1.50 is a milder myopia than minus 4.00.
The numbers usually step up in 0.25 dioptre increments. Seeing values like minus 2.00 or minus 2.25 on your prescription is perfectly ordinary.
The Difference Between Myopia and Hyperopia
Myopia and hyperopia are often mixed up. With myopia the distance is blurry, while with hyperopia the eye works harder up close. If you want a closer look at how a myopia number forms and how its strength is measured, you can read our myopia guide.
CYL Cylinder and AXIS Axis Values
The CYL column shows the cylinder value, which is your astigmatism number. Astigmatism comes from the cornea or the lens of the eye being slightly oval instead of evenly curved. Because of this both distance and near vision can look a little blurry or shadowed. If the CYL box is empty, you have no astigmatism.
AXIS means axis and it is filled in only when astigmatism is present. This value gives an angle between 1 and 180 and describes the direction of the astigmatism in your eye. CYL tells you the strength while AXIS tells you the direction. The two always work together.
You can picture the axis like a clock face. Ninety degrees represents the vertical direction and 180 degrees the horizontal one.
If you see an astigmatism value on your prescription and wonder what to do, we went into more detail in our astigmatism article. An astigmatic lens is made with a bit more care than a standard one, and processing the axis correctly is what determines clarity. If the axis is entered wrong, the lens may not give the sharpness you expect.
What the Plus and Minus Signs Mean
The signs are the part people ask about most. In the SPH column a minus sign means myopia and a plus sign means hyperopia. In the CYL column the sign depends on how the lens is written. That is why the same eye can be shown with a plus or a minus cylinder at different opticians.
This difference does not mean your prescription is wrong. Whether the cylinder is written in plus or minus form, the correct conversion produces the same lens. Your optician handles that conversion, and what matters is that the lens you see clearly through gets made. If it confuses you, show us the prescription and we will check together which form it is written in.
The ADD Value and Your Near Vision Number
ADD is not always on the prescription. We usually see it on the prescriptions of customers aged 40 and over. This value is the extra number added for near vision, and it makes up for the age-related near focus difficulty called presbyopia. Around the age of forty the eye loses some of its flexibility to focus up close, so this extra number comes into play.
ADD is always a plus value and it is often the same for both eyes. Adding this extra number to your distance figure brings reading or computer distance into focus. Bifocal or progressive lenses are made around this value. If your prescription has an ADD, the frame choice needs a bit more attention too.
Some people prefer a separate pair of reading glasses for near, while others choose a progressive lens that combines everything in one frame. If you switch between distance and near often through the day, a progressive lens is usually more practical. We look at which solution suits you based on your daily life.
Why PD or Pupillary Distance Matters
PD is the distance between your two pupils and it is measured in millimetres. In adults it usually ranges from 54 to 74 millimetres. This value makes sure the optical centre of the lenses sits right in front of your pupils. In children the measurement changes with growth, so it is taken again with every new pair.
If the PD is wrong, the sharpest point of the lens shifts away from the centre of your eye. That can cause headaches, eye strain and general discomfort. With high numbers and progressive lenses especially, an accurate PD directly affects clarity. This is why we take this measurement separately at our store when we prepare your lenses.
Some prescriptions list a single PD value while others give a separate measurement for each eye. Both are correct and both help seat the centre of the lens in the right place. A separate measurement for each eye gives a more precise result, particularly with progressive lenses.
Prism and Other Abbreviations on a Prescription
Some prescriptions also carry a column marked Prism. This value is added when there is a misalignment in how the eyes point, so the lens can steer the light, and it comes with a Base that shows the direction of that base. On most prescriptions this box is empty, and that is completely normal.
At the bottom of the sheet you sometimes find visual acuity notes such as VA or Snellen. These are not used in making the lens, they simply record how sharply your eye sees at that moment. Bring your prescription in and we will explain every abbreviation that puzzles you one by one.
How to Choose the Right Lens in Izmir
Once you understand your prescription, the next step is the right lens and frame. When you have glasses made in Izmir, the lens thickness, coating and lens type that suit your number all come into play. For high numbers a thin lens, and for people who spend a lot of time in front of screens a blue light filter lens, answer different needs. As much as the lens, a frame that fits your face shape decides your daily comfort.
If your number is high, a thinned lens changes both the look and the weight of the glasses. When you renew your lenses, our lens replacement service lets you keep your existing frame. From the Bornova side you can reach our Kemalpasa shop in about 15 minutes, and from the Buca direction in about 25 minutes. Customers from the neighbouring districts east of Izmir can have us read their prescriptions with ease as well.
Bring Your Prescription to Us in Kemalpasa
Reading the prescription in your hand is easier now. Still, if there is a value you are unsure about, you are welcome to drop by our store in Kemalpasa. We read it line by line together and show you what each number means. Our shop on Mehmet Akif Ersoy Mahallesi, Kirazli Caddesi is here for exactly that.
If you are not sure your number is up to date, we suggest an eye test first. A current measurement is always more reliable than an old prescription in your hand. If you want to ask before setting out, message us on WhatsApp, and when it is not busy you can have your measurement done the same day. When you stop by with your prescription, we go over what each number means together and help you choose the lens that fits you best.
