The two types of contact lenses that are used by most nearsighted people are “soft” lenses and Rigid Gas Permeable (RGP) lenses. However, “soft” contact lenses are unable to correct astigmatism, and most people with keratoconus experience both myopia and astigmatism. The National Keratoconus Foundation (NKF) describes an abnormally-shaped cornea (with progressive thinning and bulging) as the primary feature of keratoconus. The result of this cornea disorder is that the refraction is adversely affected (and myopia and astigmatism are the consequence of this refraction abnormality).
RGP contact lenses have been the “standard” treatment for adolescents and adults with keratoconus, but advances in contact lens development have led to the increased utilization of scleral contact lenses. Described below are some of the “pros” and “cons” associated with these two different types of contact lenses, so that – as a person living with with keratoconus – you can decide which type will best meet your needs.
Cornea Pain and Wearing Contact Lenses
Many people living with keratoconus experience corneal pain, and this is primarily due to disruption of the cornea’s surface cells and progressive corneal bulging. Since both “soft” and RGP contact lenses rest on the outer edge of cornea, these types of contact lenses can increase corneal-related eye pain (and, thus, limit the duration that the lenses can be comfortably-worn).
In contrast, scleral contact lenses rest on the sclera (white) of the eye. Therefore, scleral lenses can be more comfortable for keratoconus-afflicted people coping with frequent corneal pain.
Light Sensitivity and Contact Lenses
One of the recognized causes of corneal pain in keratoconus-afflicted people is light sensitivity. According to the National Organization for Rare Disorders (NORD), sensitivity to light and glare is one of the key features of keratoconus (besides myopia and astigmatism). Sunglasses can be worn over contact lenses to decrease sunlight (and/or glare) exposure – whether RGP contact lenses or scleral contact lenses. This is especially critical for keratoconus-afflicted people who enjoy outdoor activities (e.g., jogging or gardening) in the summer months.
Care of RGP Contact Lenses and Scleral Contact Lenses
Cleaning, disinfection, and correct storage are important aspects of utilizing either RGP or scleral contact lenses. Most cleaning solutions used for cleaning soft contact lenses are not appropriate for either RGP or scleral contact lenses (and scleral contact lenses are made of RGP materials).
The American Academy of Ophthalmology (AAO) includes the following in its list of recommendations regarding proper contact lens care:
- Never put contact lenses in your mouth to lubricate them as saliva is not a sterile solution (and use of a non-sterile solution can result in an eye infection);
- Do not rinse or store your contact lenses in water;
- Each time contact lenses are disinfected by you, utilize “new” solution (rather than re-using previously-used solution) to avoid bacterial colonization on the contact lens;
- Make sure the solution “tip” does not touch any surface (and any part of the contact lens) to avoid undermining the solution’s sterile property
Either separate cleaning and disinfectant solutions can be used – or one single, multi-purpose solution can be used – for the care of RGP contact lenses. However, the hygiene, care, and compliance protocol for scleral contact lenses is more complicated (per an article in 2017 in the Journal of Contact Lens Research and Science).
One reason for this increased complexity is that some people who wear scleral lenses prefer to utilize a scleral lens plunger to insert the scleral lens correctly in the eye (rather than a finger tip). Therefore, the scleral lens plunger must also be cleaned and disinfected.
Whether RGP contact lenses or scleral contact lenses are better for you will depend in large part upon your keratoconus symptoms. The professionals at the Precision Keratoconus Center are available to assist you in understanding your keratoconus treatment options.