Choosing the right contact lenses requires focusing on several key points. The cornea, the outermost layer of the eye, is soft and elastic. Although it is only about half a millimeter thin, its structure and function are highly sophisticated, providing 74% of the eye’s refractive power. Since contact lenses come into direct contact with the corneal surface, wearing them inevitably hinders the cornea’s oxygen uptake to some extent. Therefore, selecting lenses should never be taken lightly.

In this regard, doctors recommend paying close attention to the following indicators when choosing contact lenses:

Material:
For comfort, choose hydrogel material, which is suitable for most daily wearers, especially those who prioritize comfort. For extended wear, opt for silicone hydrogel material, which offers high oxygen permeability and is ideal for people who spend long hours in front of computers.

Base Curve:
If you have never worn contact lenses before, you can visit an ophthalmology clinic or an optical store for testing. The base curve of the lenses should be selected based on the curvature radius of the front surface of the cornea. Typically, a base curve of 8.5mm to 8.8mm is recommended. If the lenses slide during wear, it is often due to a base curve that is too large. Conversely, a base curve that is too small can cause eye irritation during prolonged wear, interfere with tear exchange, and lead to symptoms such as hypoxia.

Oxygen Permeability:
This refers to the lens material’s ability to allow oxygen to pass through, usually expressed as the DK/t value. According to the International Association of Contact Lens Educators, daily disposable lenses should have an oxygen permeability greater than 24 DK/t, while extended-wear lenses should exceed 87 DK/t. When selecting lenses, opt for those with higher oxygen permeability. However, it is important to distinguish between oxygen permeability and oxygen transmissibility: Oxygen Transmissibility = Oxygen Permeability / Central Thickness. Avoid being misled by the oxygen permeability value listed on the packaging.

Water Content:
Generally, a water content within the range of 40% to 60% is considered appropriate. Additionally, better lens moisture retention technology can improve comfort during wear. However, note that higher water content is not always better. While higher water content makes lenses softer, it can actually lead to drier eyes during prolonged wear.

In summary, choosing contact lenses requires a comprehensive consideration of your individual eye condition, wearing habits, and needs. Before wearing them, undergo an eye examination and follow your doctor’s advice to ensure eye health.