Specialty Contact Lenses Specialty contact lenses include medically necessary contacts, custom cosmetic lenses and orthokeratology. Medically Necessary Contact Lenses
Medically necessary contact lenses are required when glasses or standard contact lenses don't correct vision adequately. They are usually used when there is a problem with the structural integrity of the cornea which reduces its refractive ability. These situations include keratconus, post-refractive surgery, corneal transplants and ocular trauma. The types of lenses that are used include rigid gas permeable (RGP), scleral, hybrid lenses and specialed soft lenses.
Rigid Gas Permeable Lenses
Rigid gas permeable (RGP) lenses are beneficial to compromised corneas because they hold their shape and provide a smooth refractive surface. Some lenses come with UV protection and transmit oxygen to the cornea well. These lenses usually require some adaptation.
Scleral lenses are a large diameter RGP lens. The larger diameter allows them to rest on the white part of the eye (sclera). This improves comfort because the sclera is not as sensitive as the cornea. The weight of the lens is distributed evenly and there is better centration. By spreading out the weight of the lens the compromised cornea can be vaulted over and provide better visual acuity.
Hybrid lenses are a combination of a soft and a RGP lens. The center part of the lens is an RGP to provide good optics and the skirt of the lens is a soft lens to have better comfort. These lenses are made by Synergeyes in Carlsbad, California.
Custom Cosmetic Lenses
These lenses are mainly used to improve the cosmetic appearance of an eye. Typically this occurs in patients that have suffered some kind of ocular trauma or complication. An example would be where one pupil is larger than the other from an injury. When contacts are worn on both eyes they look the same. Standard colored contacts might work in situations like this, but they lack the individualization and custom appearance that can be created when painted by hand.
Orthokeratology ("Ortho-K") is a newer method of correcting refractive error without continually wearing glasses or contact lenses. The way Ortho-K works is that it molds the shape of the epithelium (outer layer) on the cornea. A specialized "reverse-geometry" RGP lens is worn overnight that properly applies pressure to shape the epithelium so that when the contacts are not worn during the day a correction is not needed. The procedure is completely reversible in a few days and has been shown to slow down the progression of myopia in the younger population. It is ideal for children that actively play sports and are bothered by contacts or glasses when they play. Paragon CRT (Corneal Refractive Therapy) has been FDA approved for up to -6.00 Diopters of myopia and up to -1.50 diopters of astigmatism.