How do contact lenses work?

Contact lenses are a popular alternative to traditional glasses. Rather than sitting within frames in front of your eyes, they are placed on the surface of your eye to help you see clearly. If you are a regular contact lens wearer, or if you’re new to contacts and want to know more, read on to learn more about how they work, as well as how replacing your lenses works. 

 

What are contact lenses?

Contact lenses are thin prescription lenses worn in "contact" with the eye. They float on the tear film layer over the cornea and correct refractive errors to help you see more clearly. Most are made of soft, comfortable, and hydrating materials, but some types are made from more rigid materials to correct more complicated prescriptions and eye conditions. In general, contacts nowadays are made from silicone or a material called hydrogel, both are soft and comfortable and a far cry from those made from glass a few decades ago.

 

How do contact lenses help to correct vision?

In general, contact lenses work in the same way that glasses lenses work – they refocus light into the correct part of your eye to help correct a refractive error in your vision. They just sit on your eyes instead of in front of them.

It’s important to note that your contact lens prescription will be different from your glasses prescription, so it’s important to have an eye test to determine your contact lens prescription.

Contacts can be worn to correct a range of eyesight problems, including:


How do multifocal contact lenses work

Just like with glasses, you can get multifocal contact lenses. They feature multiple powers of vision correction built into the same lens, which you look through depending on the task you’re doing. The areas work the same as a monovision contact lens – refocusing light into your eye correctly. They’re usually offered to those with presbyopia to help with everyday tasks without the need to constantly swap out their glasses.


How do monovision contact lenses work?

Monovision contact lenses provide a balance of distance and near vision for those with presbyopia by providing full distance correction to the 'dominant' eye and closer vision in the 'non-dominant' eye. Our Optometrists are trained to identify your specific ocular dominance when fitting these lenses. This can be a good solution if multifocal lenses cannot be tolerated.


Replacing your contact lenses

There are many different types of contact lenses, and how quickly you replace them will depend on the specific type you wear. 

Disposable dailies are designed to be worn for a day and thrown away – they’re very convenient for those with busy lifestyles or if you’re only wearing them occasionally. Monthly lenses are worn repeatedly for a month – you remove and clean them every night – and are replaced after that month. Some other types of lenses are worn for longer periods of time without the need to be removed and cleaned. The type you choose will depend on your lifestyle, prescription strength, and the size and shape of your eye. Your optician will be able to give you advice and guidance on the care of your lenses at your appointment.

For daily and monthly contact lenses, you will usually set up a subscription through your local Leightons branch. We’ll make sure you get a new delivery of contact lenses when you need them

 

Takeaway

Contact lenses work the same way that traditional glasses do – they refocus light into your eyes to help you see clearly. They can help with a wide range of different eyesight problems, but the specific type you wear will depend on your prescription, eye size and shape, and lifestyle. If you have any concerns about your eyesight or about your contact lenses, you should speak to your opticians or optometrist. 

Book your free eye test today to see if you’re eligible for contact lenses.

 

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Are contact lenses and glasses prescriptions the same?
Are contact lenses and glasses prescriptions the same?
While both glasses and contact lenses do the same job in correcting your eyesight, there are some obvious differences in how each is worn. Glasses rest on the nose and are positioned away from the eyes, whereas contact lenses are in direct contact with your eyeball. These differences are the fundamental reasons why contact lenses and glasses prescriptions are absolutely not the same. In this article, we’ll explain why in more detail. Contact lens vs glasses prescription – what’s the difference? Quite simply, the lenses in your glasses will be very different to your contact lenses. That’s because each type of lens refracts light differently and therefore during an eye test, different measurements have to be made. The measurements from one eye test are not compatible with the other. So, is the prescription for contacts the same as glasses? The answer is NO because you need to have 2 separate eye tests, which will result in 2 different prescriptions. Contact lens prescription A contact lens prescription comprises a set of measurements relating to the curvature, size and power of the contact lens along with other relevant information. These measurements are carried out by an optometrist, also known as an ophthalmic optician. Glasses prescription An optometrist or ophthalmic optician is also responsible for carrying out the actual eye tests for glasses and lenses. The tests are to determine the strength of the lenses you require, along with other factors such as eye dominance, pupillary distance and axis number. All this information will be included in your glasses prescription. Learn how to read your glasses prescription How to read your contact lens prescription Have you ever wondered what all the abbreviations and letters on your contact lens prescription mean? Read on to find out. What does Base Curve (BC) mean? Base Curve (BC) refers to the specific curve with which a contact lens is made. Different corneal curves will need different base curve lenses, although with modern more flexible contact lens materials, there is some lea way in this. What does Diameter (DIA) mean? This measurement refers to the Diameter (DIA) of the contact lens itself and corresponds with the size of your cornea. It is the measurement from one edge of the lens to the other and is measured in millimetres. What does Power/Sphere (PWR/SPH) mean? The term Power (PWR) together with Sphere (SPH) refers to the strength of the lens. For long-sightedness this figure will show a plus sign (+) and for short-sightedness, it will begin with a minus sign (-). Other contact lens prescription figures People who have an eye defect such as astigmatism, will need to wear toric lenses and therefore will see additional words or abbreviations on their prescription. The same applies to people who might have presbyopia or short-sightedness, and have a prescription for varifocal or multifocal contact lenses. Other contact lens prescription figures are Prism, which refers to a lens or lenses that are designed to correct double vision. Also, Pupillary Distance (PD), which is a term that relates to the distance between the centre of your pupils. It is measured in millimetres and it is important that this measurement is accurate to ensure clear and comfortable vision. OD - Stands for Oculus Dexter, which means ‘right eye’ OS - Stands for Oculus Sinister, which means ‘left eye’ BAL - Stands for Balance, which means both eyes are prescribed the same lenses. DS - Stands for Dioptres Sphere, which means the eyes are spherical in shape. VA - Stands for Visual Acuity, which is a measurement of how clearly a person can see with corrective lenses. This measurement is expressed as a fraction. Your contact lens prescription might also include the brand or manufacturer’s name. What does Cylinder (CYL) mean? The term Cylinder (CYL) refers to an astigmatic prescription. if you have astigmatism then your eye will be more oval-shaped as opposed to globe-shaped. With this condition, you would need specially designed contact lenses called Toric lenses. What does Axis (AX) mean? Axis (AX) refers to the angle that the cylinder or astigmatic correction is placed in order to provide clear vision. This is a number, which is measured in degrees from 0 to 179. What does Addition (ADD) mean? The term Addition (ADD) refers to the amount of additional correction required to see clearly nearby and is given over and above the distance contact lens prescription. Multifocal contact lenses will have an ‘add’ in their prescription. An ‘add’ is generally only required when you develop presbyopia (an age related inflexibility of the intraocular lens, that typically starts between age 40and 45) What does Dominant mean? Most people have a Dominant eye which they unconsciously favour slightly, and a non-dominant eye. Certain contact lenses are best fitted taking this into account (generally multifocal contact lenses). Typically the dominant eye is fitted with the D lens (for better Distance vision) and the non-dominant eye is for better Near vision (this would be the N lens). Can you convert a glasses prescription to a contact lens prescription? No, it’s not possible to do this because the optics of the lenses are different. Likewise, you cannot convert a contact lens prescription to a glasses prescription. How to get a contact lens prescription If you would like to know how to get contact lenses then you will first need to make an appointment with your optician for a contact lens prescription. Your appointment with your optician will include an assessment and a contact lens eye test. This is a different eye test to the type you would need for glasses. After your initial assessment and test, you will then need to have a contact lens fitting. Your optician will demonstrate how to safely insert and remove your lenses and how to care for them. Finally, you will receive your free written contact lens prescription. You can buy your contact lenses from the optician that carried out your eye test or you can buy them from another optician or an online supplier. Contact lenses need to be reviewed more frequently You should be aware that your eyesight can change over time so it’s important you get your eyes retested at least every 2 years. If you notice any changes in your vision at any time before that period then contact your optician for a check-up. Book a contact lens consultation today.
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