– Ed
Although scleral lenses have been around for a very long time, success was limited, because it was difficult to get oxygen to the cornea. Corneas are avascular and receive oxygen from the atmosphere. In recent years, drastic advances have been made with manufacturing techniques, gas permeable materials and very sophisticated equipment such as Optical Coherent Tomography and Corneal Topography. This has resulted in scleral lenses becoming hugely successful in fitting people with irregular corneas, whom otherwise were destitute and had run out of options to regain good vision.
Scleral contacts are large-diameter gas permeable contact lenses specially designed to vault over the entire corneal surface and rest on the “white” of the eye (sclera). In doing so, scleral lenses functionally replace the irregular cornea with a perfectly smooth optical surface to correct vision problems caused by keratoconus and other corneal irregularities. Advances in lens design technology are allowing manufacturers to design scleral lenses that can correct more conditions than ever before, including bifocal scleral lenses for the correction of presbyopia.
The space between the cornea and the back surface of a scleral lens acts as a fluid reservoir to provide comfort for people with severe dry eyes who otherwise could not tolerate contact lens wear.
Types Of Scleral Contact Lenses

Scleral contacts are noticeably larger than standard gas permeable (GP) contacts and have a diameter equal to or greater than that of soft contact lenses. The smallest sclerals are approximately 14.5 mm in diameter, and the largest can be up to 24 mm.
In comparison, most conventional GP contact lenses are 9.0 to 9.5 mm in diameter and cover only 75 to 80 percent of the cornea. Another category of gas permeable lenses bridges the size gap between conventional GP lenses and mini-sclerals. These lenses, called corneo-scleral lenses, generally are approximately 13 to 15 mm in diameter.
During the contact lens evaluation examination, the optometrist will determine the size lens that will work best. Trial lenses are fitted and assessed in terms of movement, centration and visual acuity.
Scleral Contact Lenses For Keratoconus
Scleral contact lenses are used for a variety of hard-to-fit eyes, including eyes with keratoconus. In cases of early keratoconus, a standard GP lens may be used. However, if the lens does not centre properly on the eye or moves excessively with blinks and causes discomfort, switching to a large-diameter scleral contact lens may solve the problem. Because scleral lenses are designed to vault the corneal surface and rest on the less sensitive surface of the sclera, these lenses often are more comfortable for a person with keratoconus. Scleral lenses are designed to fit with little or no lens movement during blinks, making them more stable on the eye, compared to traditional corneal gas permeable lenses.
Scleral Contact Lenses For Other Eye Problems
In addition to keratoconus, scleral contact lenses can be used for eyes that have undergone a cornea transplant, for people with severe dry eyes caused by conditions such as Sjogren’s syndrome, graft-versus-host disease (GVHD) and Stevens-Johnson syndrome. Very often, fantastic results are achieved with scleral lenses when all other options have failed, regaining the precious gift of sight.