For many patients with keratoconus adequate and functional vision correction can only be obtained with the use of contact lenses. Contact lenses serve to neutralize or “mask” the deleterious effects on vision induced by the irregular corneal surface found in keratoconus. The regular anterior surface of the contact lens sharply focuses light toward the retina. For a large percentage of patients with keratoconus this results in significantly improved vision compared to that obtainable with glasses. However, a significant number of individuals with the disease experience contact lens discomfort and intolerance. Many of these people are compelled to move forward with corneal transplantation as their only choice to obtain improved vision. The discomfort associated with contact lens wear may be due to the design of lens used, the materials that they are manufactured from, the physical fitting characteristics of the lenses, solutions used for lens care, or possibly environmental factors. In this column I will present some effective approaches to improving contact lens comfort in keratoconus.

Lens Designs and Materials
As one would imagine, fitting a highly irregular surface such as is found with keratoconic corneas is a great challenge. Over the past number of years a series of specially designed gas permeable contact lenses have been developed to address this issue. Through the use of multiple curves generated on the back surface of the contact lens we have been able to achieve improved lens to cornea fitting relationships. This has resulted in lenses that no longer harshly “bear” on the apex of the cone. As such, many patients have achieved improved comfort with their contact lens wear. Some patients experience lens discomfort and intolerance that is not addressed by the new gas permeable keratoconic lens designs. Many of these patients are successful with the use of “piggyback lens systems”. As the name implies, piggyback lens systems incorporate a combination of both soft and gas permeable lenses. A relatively thin soft lens is fit on the surface of the eye and the keratoconic gas permeable lens is worn over the soft lens. This often provides the best of both worlds. The soft lens drapes over the surface of the cornea which significantly improves comfort, while the gas permeable lens continues to mask the irregular corneal surface, thus resulting in improved visual performance. Most commonly, we use a soft disposable contact lens with very high oxygen transmission in our piggyback systems. This results in excellent eye health and also addresses the issues of soft lens tearing and loss. There are contact lens care systems available that can be used for both the soft and gas permeable lenses which make the use of the piggyback system much less inconvenient. Finally, one of the most exciting developments in contact lens designs is specialty soft contact lenses for keratoconus. In the past only rigid lenses were effective in masking the corneal distortion associated with keratoconus. Recently soft lenses have been developed that perform wonderfully for many patients in this regard. These designs incorporate relative thick central “treatment zones” and thin peripheral “fitting zones”. The outcome is excellent visual performance, significantly improved comfort, and healthy physiological response to contact lens wear. These lenses are custom designed for keratoconic patients based on their individual requirements of lens thickness, curvatures, and prescription powers.

Solutions and Lens Care Systems
One of the most frequently overlooked causes of contact lens discomfort and intolerance relate to the care systems and solutions used. Most contact lens care systems use preservatives to prevent contamination by microorganisms. The problem is that a small percentage of patients are sensitive to these preservatives and develop eye irritation and redness secondary to the long term use of these solutions. Symptoms of solution sensitivity include generalized irritation, burning, itching, redness, mucous or stringy discharge, and overall decrease in contact lens wearing comfort. Laboratories have been very hard at work developing new lens care systems that are able to be effective in disinfection of contact lenses while improving lens wearing comfort. A number of new care systems have been developed that use preservatives with far lower rates of sensitivity response. In addition, other lens care systems have been developed without the use of any preservatives (preservative-free lens care systems). Proper diagnosis of solution reactions by eye care professionals and the appropriate modification of the systems used go far in allowing keratoconic patients to remain in contact lenses without discomfort.

Environmental Factors
Numerous studies have suggested that keratoconic patients suffer from environmental sensitivities and allergies at significantly higher rates than the general population. The wearing of contact lenses acts to create a surface where the elements that cause allergic reactions (known as “antigens”) can accumulate and bind. The increased antigen load found in contact lens wear further increases the frequency and severity of allergic reactions in keratoconic patients. There are a number of things can be done to reduce the allergic responses all year round, but especially bothersome during the peak allergy seasons of the spring and fall. First, make sure that you keep your lenses clean and as free from deposits as possible. If you wear gas permeable lenses, they can be cleaned and polished professionally at your eye care professional’s office. Also make sure that you replace your lenses at frequent intervals. Second, consider using lubricating and wetting drops to help “flush” antigens that are not bound to the lens surface. Finally, your doctor may consider prescribing some of the highly effective new medications that work at the core mechanisms of the ocular allergic response. Most of these medications are highly effective, very safe, very convenient in terms of frequency of use, and can be used for prolonged periods of time without concern for complications associated with long term use.

Conclusion
Contact lenses remain as the mainstay treatment modality for keratoconus. By taking advantage of contemporary science in the fields of lens design, lens materials, care/solution systems, and ocular medications, we can provide long term comfort and visual performance for our keratoconic patients. Make sure that your doctor is highly skilled and experienced in the contact lens management of keratoconus. There are many highly qualified professionals available that can help maximize your likelihood of successful contact lens wear.

Dr. Eiden is president and medical director of North Suburban Vision Consultants in Deerfield, Illinois which is a group eye care practice with special interest in contact lenses and the management of ocular disease. www.nsvc.com , an Assistant Clinical Professor in the Department of Ophthalmology at the University of Illinois at Chicago Medical Center. He is a frequent author and lecturer on topics related to specialty contact lens management.