Most people wear contact lenses every day without ever thinking about what they are actually made of. Yet the material a lens is made from determines how much oxygen reaches your eye, how long you can wear it comfortably, and whether it suits your lifestyle. This guide breaks down the main contact lens materials, explains water content, and answers a question many coloured lens wearers ask: what exactly gives the lens its colour, and is it safe?
Contact lenses are made primarily from hydrogel or silicone hydrogel, both soft water-containing materials that allow oxygen to reach the cornea. Rigid gas permeable (RGP) lenses use fluorosilicone acrylate polymers. Coloured contact lenses use the same base materials with added pigment layers, which in regulated lenses are safely encapsulated within the lens rather than touching the eye surface.
The Three Main Contact Lens Materials
The material a lens is made from directly affects its oxygen permeability, water retention, and how long it can be worn safely. There are three broad categories used in lenses available today, each suited to different needs and prescriptions.
Hydrogel
Hydrogel was the first soft contact lens material, developed from a polymer called poly-HEMA (poly-2-hydroxyethyl methacrylate) in the 1970s. These lenses absorb water to remain soft and flexible, and oxygen reaches the cornea by dissolving through that water content. The water content of hydrogel lenses typically ranges between 38% and 75% by weight. They feel very soft on the eye and are straightforward to adapt to, making them a popular choice for first-time wearers and for coloured cosmetic lenses. The main limitation is that hydrogel can lose moisture over time, which may cause end-of-day dryness during longer wear sessions.
Silicone Hydrogel
Silicone hydrogel was introduced in the late 1990s and represented a significant step forward in lens technology. Rather than relying on water to carry oxygen to the cornea, the silicone component allows oxygen to pass directly through the material itself, independent of water content.
This makes silicone hydrogel lenses up to five times more oxygen permeable than standard hydrogel lenses, which is particularly beneficial for people who wear lenses for twelve or more hours a day, have dry eyes, or need extended wear options. Silicone hydrogel lenses can feel marginally firmer than hydrogel lenses and may attract lipid deposits slightly more readily, but for daily or extended use they remain the most widely prescribed soft lens material.
Rigid Gas Permeable (RGP)
RGP lenses are made from fluorosilicone acrylate polymers, which are rigid but highly oxygen permeable, achieving Dk values that exceed most soft lenses. They hold their shape on the eye, which produces sharper vision and makes them particularly effective for correcting astigmatism and irregular corneal conditions such as keratoconus. RGP lenses require a longer adaptation period and are less commonly chosen for cosmetic use, but they offer durability, optical precision, and excellent corneal health when properly fitted.
Understanding Water Content
Water content is one of the most visible specifications on contact lens packaging, always expressed as a percentage. For hydrogel lenses, it has a direct impact on how the lens behaves throughout the day. A common misconception is that a higher water content always means a more comfortable lens, but the reality is more nuanced.
|
Level |
Water % |
Characteristics |
Best for |
|---|---|---|---|
|
Low |
Below 40% |
Thinner, less prone to dehydration during long wear |
Wearers prone to dry eyes |
|
Medium |
40–60% |
Balanced comfort and durability throughout the day |
Most everyday wearers |
|
High |
Above 60% |
Very soft and moist initially, can dry out after several hours |
Short wear sessions, healthy tear film |
The table above shows why medium water content lenses are the most widely used. High water content lenses feel noticeably moist initially but can draw moisture away from the eye as they begin to dehydrate, which is the opposite of what dry-eye wearers need. Silicone hydrogel lenses are less affected by this issue because their oxygen transmission does not depend on water at all.
For more detail on the measurements that affect lens fit and comfort, see our guide on base curve and diameter in contact lenses.
What Are Coloured Contact Lenses Made Of?
Coloured contact lenses are built on the same base materials as clear lenses. What sets them apart is the addition of a colour layer, and how that layer is integrated into the lens is what determines both the visual effect and the safety profile of the product.
The Base Material: Polymacon and Silicone Hydrogel
Most soft coloured lenses, including the Bella range, use Polymacon as their base material. Polymacon is the most widely used form of hydrogel, known for its softness, stable shape, and ability to support detailed print patterns without affecting the optical zone. Bella lenses are made with Polymacon at 55% water content and a Dk value of 8.4, which provides consistent comfort during the recommended daily wear period. Some premium coloured lenses use silicone hydrogel as their base, offering higher oxygen permeability for wearers who need longer daily wear times.
How the Colour Pigment Works
In a well-manufactured coloured lens, the pigment is placed between two thin layers of lens material in a process known as encapsulation. The colour layer sits sandwiched within the lens body rather than sitting on the outer surface. This means the pigment never comes into direct contact with the cornea or the inner surface of the eyelid. The result is a lens that changes the apparent eye colour while the surfaces that touch the eye remain smooth, pigment-free, and safe for regular wear.
Is the Pigment Safe?
In regulated lenses from established brands, the pigment does not affect the oxygen permeability of the lens. A clinical study by Galas and Cooper confirmed that pigment in the optical zone of cosmetic daily disposable lenses did not statistically influence oxygen transmission. The risk arises with unregulated or counterfeit lenses, where pigment encapsulation may not meet safety standards, and the dyes used may cause irritation or, in serious cases, damage to the ocular surface.
This is why all contact lenses in the UK, including coloured ones, are classified as medical devices and require a valid prescription and professional fitting before purchase. For a broader overview of safe lens wear practices, our guide on are contact lenses safe covers the key principles.
Bella coloured lenses are soft lenses made with premium Polymacon material and safely encapsulated pigment. Explore the full range: Bella Coloured Contact Lenses.
Contact Lens Material Comparison
No single material suits every wearer. The right choice depends on how long you wear your lenses each day, whether you experience dry eyes, and what type of lens you need. The table below summarises the key differences at a glance.
|
Material |
Oxygen Transmission |
Texture |
Best for |
Less suited for |
|---|---|---|---|---|
|
Hydrogel (Polymacon) |
Via water content |
Very soft |
Short–medium daily wear, coloured cosmetic lenses |
Extended wear, severe dry eyes |
|
Silicone Hydrogel |
Directly through material |
Soft (slightly firmer) |
Long daily wear, extended wear, dry eye management |
Those sensitive to silicone or preferring softer feel |
|
RGP (Gas Permeable) |
Highest – through rigid material |
Rigid (needs adjustment) |
Irregular corneas, high astigmatism, keratoconus |
First-time wearers, active sports |
For most daily coloured lens wearers, Polymacon hydrogel offers the ideal balance of softness, colour fidelity, and comfort within the recommended 8–10 hour wear window. Silicone hydrogel is the better choice for anyone wearing lenses beyond that or managing contact lens-related dryness. If you are unsure which material suits your prescription and lifestyle, our guide on choosing the right contact lenses for your lifestyle walks through the decision in detail.
What the Numbers on Your Contact Lens Box Mean
Contact lens packaging contains several technical values that directly relate to the material and how it performs. Understanding the key ones helps you make informed comparisons between brands and products.
Material name: The polymer used in the lens, such as Polymacon, comfilcon A, or senofilcon A. This tells you whether the lens is hydrogel or silicone hydrogel.
Water content (%): The proportion of the lens made up of water. For hydrogel lenses, this directly influences oxygen transmission and how the lens feels throughout the day.
Dk/t value: The measure of oxygen transmissibility through a lens of a given thickness. A higher Dk/t means more oxygen reaches the cornea. For reference, Bella lenses have a Dk of 8.4, appropriate for daily soft lens wear.
BC / DIA (Base Curve / Diameter): These measurements define how the lens fits on your eye rather than the material itself, but they appear on every box alongside material specifications. For a full explanation of these values, refer to our guide on base curve and diameter.
Final Thoughts
Understanding what contact lenses are made of is the first step to choosing a pair that genuinely suits your eyes. Whether you opt for soft hydrogel for everyday coloured wear or silicone hydrogel for longer daily use, the material directly affects comfort, eye health, and how long you can wear your lenses safely. For a deeper look at matching material to your prescription and lifestyle, see our contact lens material selection guide.
See more: A Guide on Contact Lens Materials
