How Silicone Hydrogel Contact Lenses Can Prevent Corneal Oxygen Deficiency?

If you are suffering from the side effects of contact lenses, it is time to switch to contacts made of silicone hydrogel. It works by improving oxygen permeability to prevent oxygen starvation of the cornea.

Corneal oxygen deficiency, also known as corneal hypoxia, occurs when there is insufficient supply of oxygen to the cornea. This is the most commonly occurring side effects of contact lenses, especially when you choose extended-wear contacts. This is a concerning problem because the cornea is one part in your body that doesn’t have a blood supply of its own.

The cornea gets its oxygen supply only from direct contact with the atmosphere and from the tears. When you wear a typical contact, it reduces the supply of oxygen to it. When you wear it overnight the supply of oxygen decreases further to the eye.

The Impact - Corneal Neovascularization

When the cornea doesn’t get enough oxygen for a long time, it can increase the chances of in-growth of new blood vessels in the avascular corneal tissue. This affects corneal transparency and reduces the clarity of your vision. This is a highly complicated situation and may require surgical intervention.

This is where modern high-permeability Silicone Hydrogel contact lenses have provided an excellent solution. Contacts made of silicone hydrogel help prevent corneal clouding and over-wearing syndrome.

Corneal Oxygen Deficiency – The Challenges

When it comes to choosing your contacts, keeping them clean should not be the only concern on your mind. You should be careful about choosing the right material. There are lens designs that can be more oxygen-friendly. But when you sleep with the contacts on, the situation can become worse. Some of the symptoms of this problem include:

• Burning sensation
• Blurred vision
• Scratchy sensation
• Excessive tears

Even in mild conditions, there can be swelling in the epithelial layer and/or temporary blurring. If you don't seek timely and proper treatment, it can also cause permanent damage to the epithelial cells. So it is extremely important to choose that are designed keeping in mind this problem.

Technical Challenges

The main challenges with regard to soft contact lens materials, meant for extended wear, included the following:

• Increasing oxygen transmissibility, measured in Dk/t
• Lower modulus
• Surface biocompability

Preventing responses like microbial keratitis has also been a challenge. The method employed to increase oxygen transmissibility of hydrogel lenses has been to increase water content and reducing lens thickness. The Holden/Mertz criterion set for minimal oxygen transmissibility, in 1984, was meant to avoid corneal edema. But most of the soft lenses could not meet this criterion.

This forced the industry to make changes and create new material to increase oxygen transmissibility. This requirement was set at 125x10-9 for the prevention of stromal hypoxia. And silicone and hydrogel were found to be the best-possible Manufacturing Contact Lenses for creating extended wear soft lenses.

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