If conventional contact lenses don’t work for you or you have had trouble wearing them, then scleral lenses may be your answer. These rigid gas permeable lenses are large and range from 14mm to 20mm diameter. They are aptly named as they cover the entire cornea (the transparent, dome-shaped covering over the colored part of the eye) and rest on the sclera (the white part of the eye).
Types of Rigid Contact Lenses
They are classified based on their size.
- Corneal lenses: Exclusively supported by the cornea and do not cover the sclera.
- Corneoscleral lenses: Cover the cornea and the sclera and rest near the junction of the cornea and sclera.
- Scleral lenses: Supported by the sclera and completely vault the cornea.
What is Keratoconus?
Keratoconus is an eye disease where the clear, dome-shaped cornea of the eye thins and bulges into the shape of a cone. The cornea normally helps to focus light into the eyes for proper vision. In keratoconus, even with updated eyeglasses, the vision is often blurry and distorted.
Lenses for Keratoconus
Scleral lenses are the most significant advance in recent years for restoring vision and managing keratoconus. Keratoconus is not always sufficiently treated with an eyeglass prescription and will need special rigid surface contact lenses. Custom contact lenses can mask the irregular cornea and provide a smooth surface for improved vision. These uniquely designed lenses rest on the white part of the eye rather than the cornea. This design makes them more comfortable for people with keratoconus since it rests on the insensitive white part of the eye.
These lenses can have a role in mild to even severe stages of keratoconus.
Other Uses
Patients with an irregular cornea, tear film conditions, and types of refractive errors and patients who are unable to benefit from other forms of correction can often wear these lenses as well.
Conditions like keratoconus, corneal scars, and even surgery like penetrating keratoplasty or refractive surgery can cause the cornea to become irregular. These individuals may benefit from wearing lenses scleral lenses.
Conditions that affect the quality and quantity of tears like dry eye syndrome, Stevens-Johnson syndrome, graft vs. host disease, Sjögren’s syndrome, and neurotrophic keratopathy can benefit from these lenses. Since these specialized lenses trap non-preserved saline against the corneal surface for the duration of lens wear, they may serve a therapeutic role in keeping the eye surface protected from drying out.
Advantages
he conjunctiva — the soft, transparent tissue that covers the sclera — is less sensitive than the cornea, which is a highly sensitive tissue. As scleral lenses rest primarily or entirely on the sclera, they produce less lens awareness compared to corneal rigid contact lenses. When appropriately prescribed, scleral lenses can approach the wearing comfort of soft disposable contact lenses.
In patients with a damaged cornea, these lenses are often a great option as it does not touch the cornea and also provides preservative-free saline to rejuvenate the corneal surface. These lenses do not move as they have a large diameter and extend under the upper and lower lid, thereby providing optimum stability and comfort.
Cost
Scleral lenses are custom-made and often require several visits with your optometrist to be appropriately evaluated and prescribed. Over 15 years ago, a pair of these special lenses and the related eye care services would total about $7,600. Today, the lenses and prescribing visits amount to less than half that cost, if paid out-of-pocket.
Several major vision benefit plans, such as Vision Service Plan (VSP) and EyeMed, have programs which recognize specific conditions to require visually necessary contact lenses. If the medical criteria are met, a “necessary contact lens” authorization may be approved, covering the entire cost of the services and scleral contact lenses, aside from any co-payment.