How much oxygen permeability is safe to achieve?

PART 01｜What is oxygen permeability (Dk/t)?

Oxygen permeability (Dk/t) is a measure of the ability of a contact lens to allow oxygen to pass through the lens and reach the cornea, and is one of the key parameters in determining whether a lens is “healthy to wear”.

You can think of oxygen permeability as the “respiratory index” of a contact lens:

A higher number means that the lens has better oxygen permeability, providing more oxygen to the cornea and helping to maintain the natural state of the eye.

The cornea itself has no blood vessels, and the oxygen it needs comes directly from the air. When wearing contact lenses, the lenses form a barrier between the cornea and the air, and oxygen permeability is the core criterion for measuring the “breathability” of this barrier.

PART 02｜Effects of Oxygen Permeation on Eye Health

Adequate oxygen supply is critical to corneal health, and oxygen permeability affects the wearing experience and eye condition in two main ways:

1. Corneal Health and Clear Vision

The cornea requires continuous access to oxygen to maintain clarity and normal metabolism. If the lens does not transmit enough oxygen, the cornea may become edematous (swollen) due to the lack of oxygen, which can lead to blurred vision, increased halo sensation, and may even affect the cornea's health if worn for a long period of time.

2. Wear time and comfort

Contact lenses with high oxygen permeability allow the eyes to “breathe” more freely, effectively reducing dryness, redness and fatigue caused by lack of oxygen. This is one of the most important factors in determining whether a lens is suitable for extended wear, or even has the potential to be worn overnight (long-wear).

PART 03｜Common Misconception: The thinner the lens, the more breathable it is?

Many people mistakenly believe that the thinner the contact lens, the more breathable it is, but in reality, oxygen permeability is not determined by thickness alone.

The “t” in Oxygen Transmission (Dk/t) represents the thickness of the lens, while it is the “Dk” - the oxygen transmission capacity of the lens material itself - that really determines the upper limit.

Comparison of the two materials:

①Traditional hydrogel lenses: mainly rely on the water in the lens to conduct oxygen, and there is a physical upper limit to the oxygen permeability.

②Silicon Hydrogel Lens: By adding silicon into the material, oxygen can be directly transmitted through the micro-channels inside the lens, and its oxygen permeability can usually reach 5 times or even higher than that of hydrogel lens, which is a real technological upgrade.

Therefore, even if the lens thickness is similar, the oxygen transmission performance of different materials may differ significantly.

PART 04｜How to choose the right contact lens according to the oxygen permeability?

Oxygen permeability is an important reference index that should not be ignored when shopping for contacts or eyeglasses. You can choose according to your own wearing habits and use environment:

▸ Everyday wear

Choosing lenses with good oxygen permeability will help maintain comfort throughout the day and reduce the strain on your eyes.

▸ Worn for long periods of time or in special environments

If you need to wear them in air-conditioned rooms, dry climates or prolonged eye use, it is recommended that you give preference to lenses made of highly permeable silicone hydrogel.

▸ Easily dry or sensitive eyes

Lenses with higher oxygen permeability are usually more helpful in relieving dryness, discomfort and are kinder to sensitive eyes.

Recommended Silicone Hydrogel Contacts and Lenses (High Oxygen Permeability Material)

If you're looking for contacts or lenses with higher oxygen permeability and greater peace of mind, focus on the following silicone hydrogel products

Pupils:

①Rabaisi: Umbrella Language Series

②Miracle: Blooming Beauty Series

③EYEPONY: Wilderness Wilderness Series

Contact Lenses:

Alcon: Water Gradient Series

MIROKON: Oxygen Mobilization Series

Labaisi: Escape from the City Series

These products are generally made of silicone hydrogel, which performs better in terms of oxygen permeability, wearing comfort and stability, and is suitable for users who pursue high comfort and eye health.