The Relationship Between Corneal Oxygen Supply and Contact Lenses 👀

The cornea receives oxygen from tears and nearby blood vessels, but most of its oxygen comes from the atmosphere. When your eyes are open, the oxygen pressure at the corneal surface is about 155 mmHg. When your eyes are closed, the oxygen supply comes from the conjunctival blood vessels, dropping the oxygen pressure to about 55 mmHg, equivalent to approximately 8% oxygen. This can cause minor corneal swelling during sleep, but it typically disappears within an hour of waking up. 😊

Oxygen Supply to the Cornea While Wearing Contact Lenses 🌬️

The way oxygen reaches the cornea differs between RGP lenses and soft contact lenses. RGP lenses allow about 10-20% of the tears between the lens and the cornea to be exchanged when blinking, providing oxygen to the cornea. In contrast, soft contact lenses allow minimal tear exchange (about 1%), so the cornea relies solely on oxygen passing through the lens. Therefore, even with similar oxygen transmission rates, corneal swelling tends to resolve more quickly with RGP lenses.

Daily Wear Lenses and Corneal Swelling 🕑

To prevent corneal swelling during the day, the oxygen pressure on the corneal surface needs to be at least 75 mmHg. This requirement is closely related to the central thickness of soft contact lenses. Daily wear lenses often do not meet this criterion, while extended wear lenses generally do. Therefore, choosing lenses with high oxygen permeability is crucial. 😊

Extended Wear Lenses and Corneal Swelling 🌙

To safely wear contact lenses overnight, it's important to select lenses with high oxygen transmission rates. Studies suggest that a minimum of 12.1% oxygen transmission (with an oxygen permeability rate of 34.3) is required to avoid corneal swelling overnight. If corneal swelling persists, it may be best to switch to daily wear lenses.

Corneal Changes Due to Hypoxia ⚠️

Prolonged oxygen deprivation in the cornea can lead to the accumulation of lactic acid and carbon dioxide, reducing the pH of the corneal stroma and increasing osmotic pressure, which can cause corneal swelling. These changes can also induce the formation of new blood vessels in the cornea or alter the corneal endothelial cells, so it’s essential to be cautious.

Reference Notes 📌

If you're considering contact lenses for a younger user, you might ask: Can a 10-year-old wear colored contacts? It's important to consult an eye care professional to ensure the lenses are safe and suitable. For young users, Daily Colored Contacts or Trial Colored Contacts are ideal options as they are easy to maintain, hygienic, and provide the necessary safety.

When selecting lenses, pay attention to the 8.4 BC colored contacts specification, which can significantly impact comfort and oxygen flow to the cornea.

For those who prefer daily wear lenses, Daily Contacts Colored options offer convenience and comfort with good oxygen permeability.

If you're looking for something vibrant, consider Neon Colored Contacts. These lenses offer a striking and unique look. They shine even brighter in dark environments or under UV lighting, delivering a more vivid color experience compared to regular colored lenses. These lenses are perfect for Halloween, cosplay, or any event where you want your eyes to stand out with bright neon colors. Neon colored contacts are typically available in fluorescent or very bright shades and are often UV-reactive, creating a more dramatic effect under blacklight. However, due to their bold design, it's important to follow proper usage guidelines to ensure eye health and safety.