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Breaking down the contact lens jargon

Breaking down the contact lens jargon

We know there are a lot of  technical terms when it comes to your eyesight, so we’ve broken them down here for you, starting with contact lens materials, to help unblur the world of vision.

Hydrogel Contact Lenses

Soft Hydrogel contact lenses are made from a gel-like, hydrated plastic known as hydrogel. This material is a popular choice due to its thin, pliable nature which provides instant comfort for the wearer. In addition to being thin, flexible and comfortable, they offer a high water content, which allows oxygen to pass through the contact lens, aiding the health of the eyes. The high water content and oxygen flow means that soft hydrogel contact lenses are ideal for dry, delicate eyes. They’re such a good material choice, WALDO contact lenses are made from Etafilcon A, one of the most popular and widely used hydrogel materials.

Silicone Hydrogel Contact Lenses

These are made from silicone and similarly to soft hydrogel contact lenses, they allow a high percentage of oxygen to pass through the and reach the eye, keeping the eyes healthy and white. Compared to hydrogel contact lenses, the silicone construction is slightly thicker and stiffer.

Gas Permeable Contact Lenses

Gas permeable contact lenses, commonly known as a hard contact lens are characterized by their highly breathable nature. However, they are produced in a fixed shape and size and therefore are more rigid contact lenses than hydrogel lenses. As a result of the rigid nature, these contact lenses often require a longer period of adjustment for the wearer.

Hybrid Contact Lenses

Hybrid contact lenses are a combination of gas permeable contact lenses but with a softer outer ring. They have a hard, gas-permeable center, which makes them as breathable as gas-permeable lenses, but the softer outer ring provides more comfort and pliability to the contact lenses, making them a more comfortable choice for contact lens wearers.

PMMA Contact Lenses

PMMA contact lenses are somewhat outdated now. PMMA, also known as plexiglass or acrylic, were  once considered the best material for contact lenses. In modern times, it is highly unlikely that contact lens wearers will come across PMMA contact lenses. The plastic composition makes the contact lens very stiff and they are not very breathable, acting as a shield preventing oxygen from reaching the eye. This lack of breathability negatively impacts the health of the eye.

So, there you have a quick breakdown of different materials contact lenses can be made of and their unique properties, strengths and weaknesses. Ensure that you always consult your Eye Doctor to determine the right contact lenses for you. To follow on from this breakdown of contact lens materials, we would like to cover some more terms which you may hear within the world of eyecare but might not be too sure on what they actually mean.


Dk/t refers to the breathability of the contact lens, in terms of how much oxygen can pass through the thickness of the contact lens. WALDO contact lenses have a Dk of 25, which allows enough oxygen to pass through the surface of the contact lens and maintain the health of the eyes. A high level of oxygen flow to the cornea is also very  important as it improves longer-term comfort of the lens. 

Water content in contact lenses

In combination with the Dk/t of contact lenses to allow oxygen to permeate the surface, the water content of a contact lens {how much of the contact lens is made up of water} is a major factor in the eye receiving oxygen. The higher the water content % in a contact lens, the more oxygen that is able to reach the cornea during lens wear. Different types of contact lenses have differing water contents. For those who wear soft contact lenses, the water content ranges from 38 to 75%. For a contact lens to be considered as having a high water content, typically it has to be made up of over 50% water.


UV stands for ultraviolet and it is a type of light that primarily originates from the sun. Healthy exposure to sunlight can have positive effects on sleeping patterns and energy levels, but too much UV can be harmful to people and in extreme cases raises your risk of eye diseases. 

Some contact lenses are manufactured with UV protection against both UVA and UVB rays. 

UVA makes up 95% of the UV radiation on earth, possessing longer wavelengths but lower energy than other UV rays. UVA has the potential to pass through the cornea and impact the eye’s retina. 

UVB accounts for the remaining 5% of the earth’s UV radiation. It is made up of medium wavelengths and can also result in lasting damage to the eye’s biological ocular tissue. 

WALDO contact lenses provide 83% UVA and 97% UVB protection to protect your eyes from sun damage.

Read more about UV rays and ways to protect your eyes against them here. 

Having trouble making sense of your contact lens prescription? We have broken it down for you here.

For the final part of this series breaking down the jargon in the world of vision, we would like to break down some terms of optical conditions.


Cataracts is a condition in which the eye’s lenses become clouded, often as a result of UV exposure. This exposure to UV causes proteins within the crystalline lens of the eye to degenerate, eventually clouding over and impairing the vision of the affected individual. If someone is suffering from cataracts, the only way to correct cataracts is via cataract surgery. This procedure involves replacing the lens of the eye with an artificial lens.


Emmetropia is not a condition as such. Instead, it is a term which is used to describe when light focuses on the back of the eye and the retina as it should. If an individual is described as having emmetropia, their eyesight requires no correction, their vision is as it should be.


Myopia is a term which is commonly referred to as short sightedness. Myopia is when the light entering the eye doesn’t quite reach the retina and focuses in front of it. Someone who experiences myopia will be able to clearly see objects if they are close to them, but if things are in the distance, things will appear blurry and distorted. In order to correct myopia, minus contact lenses are used to correct the focal point of light. The contact lenses diverge the light so that it will focus on the back of the eye, correcting the long-distance sight of those with myopia.


Hyperopia, often known as long sightedness, is a condition in which incoming light focuses behind the retina. Hyperopia is the opposite of Myopia. An individual who lives with hyperopia would be able to clearly see things in the distance, but when objects are in close proximity, they will appear blurry. In order to correct hyperopia, plus contact lenses are used. Plus contact lenses work by converging the light so that it focuses on the retina correctly.


Astigmatisms occur when the light which enters the eyes focuses at more than one point within the eye. This can be a result of the eye being more rugby ball shaped, as opposed to being more rounded like a football. In order to correct astigmatism, Toric lenses with different prescriptions for each eye are required, to account for the differences in shape of the two eyes.


Presbyopia is a condition which often occurs over the age of 40. With age, the lens within the eye loses flexibility and starts to stiffen, which leads to the eye losing its ability to adjust and focus on objects which are in close proximity. In order to correct this, multifocal lenses are used to, due to their ability to correct distance and close proximity eyesight.

There is a comprehensive breakdown of some of the most common eyesight conditions. If you think you may be experiencing any of these symptoms, make sure to visit your optician and get a professional diagnosis.

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