The phrase “permanent contact lenses” refers to Implantable Collamer Lenses (ICLs), a type of Phakic Intraocular Lens. These devices are surgically positioned inside the eye to correct vision, offering a long-term alternative to glasses and external contacts. Unlike procedures that reshape the cornea, ICLs function as an internal corrective lens, preserving the eye’s natural structure. This approach provides a solution for many individuals with high prescriptions or other eye characteristics that may disqualify them from laser vision correction.
Clarifying Terminology: Implantable Lenses
An Implantable Collamer Lens (ICL) is a specialized, thin lens surgically placed within the eye, specifically between the iris and the natural lens. This placement means the lens is invisible to the outside world. The term “phakic” indicates that the eye’s natural lens remains in place, unlike in cataract surgery where the natural lens is removed.
The lens material, called Collamer, is a patented blend of polymer and collagen, making it highly biocompatible with the human eye. This unique composition allows the lens to be soft, flexible, and moist, ensuring it integrates well without causing irritation. Because the ICL does not alter the cornea’s shape, it can offer exceptional visual quality and is often a preferred option for patients with thin corneas or chronic dry eyes.
The Intended Lifespan of ICLs
ICLs are designed to be a permanent solution for vision correction, intended to last for the patient’s entire life. The longevity is attributed to the material science of Collamer, which is stable and resistant to breaking down or degrading within the eye’s environment. The material’s durability is such that it is engineered to remain functional for a century.
Clinical data and long-term studies have affirmed the stability and effectiveness of ICLs over extended periods, with many patients maintaining clear vision for over a decade. This performance is due to the lens’s placement inside the eye, which protects it from external wear and tear.
The permanence of the ICL offers stable vision correction. However, the continued success relies on the overall health and stability of the patient’s eye. Even with age-related vision changes, the implanted ICL continues to correct the original refractive error.
Necessary Long-Term Care and Monitoring
While the implanted lens is designed for permanent placement, the eye remains a dynamic biological system that requires ongoing observation. Regular, long-term monitoring by an eye care specialist is necessary to ensure the ICL continues to function optimally.
The standard practice involves annual check-ups after the initial post-operative period to track the stability of the lens and the health of the eye’s internal structures. Specific measurements are performed, including checking the intraocular pressure (IOP) to prevent glaucoma. The position of the ICL, known as the vault, is also measured to ensure it is correctly aligned and resting at a safe distance from the natural lens.
Another measurement includes the endothelial cell count (ECC), which monitors the health and density of the cells lining the back of the cornea. Acceptable loss of these cells is generally less than 5% in the first year and then less than 1–2% per year thereafter.
Reasons for Potential Revision or Removal
Despite the intended permanence, ICLs have the advantage of being reversible, meaning they can be safely removed or replaced if a medical need arises. The need for revision is the exception, typically driven by changes in the patient’s eye health, not a failure of the lens material.
One of the most common reasons for removal is the eventual development of cataracts, which is a normal age-related change. When the natural lens becomes cloudy, the ICL is removed during the same procedure as the cataract surgery.
Other potential reasons for exchange or explantation include significant changes in the vision prescription years after implantation, or a need to correct inaccurate sizing from the initial procedure. For example, an improperly sized lens, known as an incorrect vault, may lead to issues like elevated intraocular pressure or early cataract formation. In these instances, the ICL can be exchanged for a different size or power.