Choosing contact lenses

Key Points for Selection

Brand

Contact lenses affect eye health, and products from major brands are safer. More advanced technology and materials can make a significant difference in experience.

Replacement Schedule

Disposable contact lenses, as the name suggests, are meant to be discarded after a certain period of use. This is due to factors such as lens wear, protein buildup, and hygiene concerns. Common types include daily, bi-weekly, monthly, semi-annual, and annual disposables. Shorter replacement schedules are more hygienic and safer.

Water Content

A common misconception is:

Higher water content is better

Water content refers to “the percentage of water by weight in the contact lens material when fully saturated”. Note that this is the percentage of water after saturation. When first worn, lenses are usually just taken out of the care solution and are fully saturated. After wearing, water content decreases due to evaporation and other factors. At this point, the unsaturated lens will absorb moisture from its surroundings to reach saturation. If the lens has too high water content and your eyes are relatively dry, you may experience discomfort and dryness. Additionally, lenses with higher water content tend to be softer, making them more difficult to handle (they bend easily during insertion and are more prone to deformation or even falling out due to external forces).

Oxygen Permeability and Material

While disposable contact lenses solved hygiene and other issues, low oxygen permeability was a major weakness of contact lenses before the 21st century, leading to significant criticism. The emergence of silicone hydrogel completely changed this situation. Silicone hydrogel is a new generation lens material that outperforms traditional hydrogel materials in all aspects, allowing nearly 99% of oxygen to pass through the lens. Personally, I’ve experienced a qualitative leap in comfort when switching from hydrogel to silicone hydrogel lenses.

Choose silicone hydrogel if possible

Base Curve

When wearing contact lenses, diameter and thickness are generally parameters that don’t require much attention. The base curve (BC) is the only dimensional parameter that has a significant likelihood of individual variation. It refers to “the curvature of the inner surface center of the lens”. Lenses with a longer base curve are flatter, while those with a shorter base curve are more curved. Base curve can be measured with specialized equipment, and a person’s base curve generally never changes. However, most people don’t need to worry about this issue. Asians generally adapt well to base curves from 8.4 to 8.8, and this range covers almost all products available on the market.

Care

Except for daily disposables, most contact lenses require care. There are typically two methods of care:

Multipurpose Solution

After removing the lenses, rub and soak them with multipurpose solution.

This is the most common method, so common that most people don’t know there are care solutions that aren’t “multipurpose”. It’s called “multipurpose” because these solutions generally include multiple functions: disinfecting, protein removal, and moisturizing. They can be used for both cleaning and storing lenses. Although they can be put directly into the eye, I don’t do this: if it can remove protein from the lens, it can certainly remove protein from your eye, just at a lower dose and concentration with less impact. Moreover, these solutions contain preservatives. A better approach is to use the solution only for cleaning and soaking the lenses, and before wearing, soak and rinse them again with saline solution. This method can also reduce eye irritation when wearing the lenses.

Hydrogen Peroxide Solution

Hydrogen peroxide solutions are much more effective at disinfecting and removing protein than multipurpose solutions. Some bacteria can only be killed by hydrogen peroxide solutions. Their usage method is completely different from multipurpose solutions, and improper use can cause eye burns. This is why many people who use it incorrectly misunderstand hydrogen peroxide solutions. Hydrogen peroxide solution itself is a strong oxidizer and cannot be put directly into the eyes. Perhaps for this reason, there are fewer products available. In China, I’ve only found one brand. I won’t introduce the specific usage method and details to avoid seeming like an advertisement. I currently use hydrogen peroxide solution for care because it doesn’t require rubbing, making it very convenient - a choice for lazy people. As long as it’s used properly, it’s much more convenient and hygienic than using multipurpose solution alone.

Summary

The material and care of contact lenses are extremely important for the user’s experience and eye health. Hydrogen peroxide solution is convenient and hygienic, but it’s crucial to carefully read the instructions. I hope you can enjoy using contact lenses.