Major innovations in contact lenses has been the rule in 2005.  With the availability of the silicone hydrogel polymer, many contact lens manufacturers are expanding their lens parameters to include this new material. It is very likely that the silicone hydrogel material will dominate the contact lens market for the next five to ten years. This contact lens update will also encompass new designs in astigmatism-correcting, multifocal and multifocal-astigmatism-correcting lenses.

Silicone Hydrogel Contact Lenses

Silicone hydrogel material brings the wettability, stability and comfort of hydrogel lenses with the exceptional oxygen transmission of the silicone polymer. Inherently, silicone resists water, not a good characteristic of a contact lens. Polymer science has found new ways to combine ingredients so that this characteristic is altered. A notable name is the Acuvue Advance lens with Hydraclear. Hydraclear is actually incorporated into the material itself and enables the lens to wet better which makes it more comfortable. With the Ciba Focus Night & Day lens, the lens surface is treated to enhance wettability. With the increased oxygen to the front of the eye, the contact lens wearer develops less corneal swelling or edema. This, in most contact lens wearers, translates into more comfort and longer wearing times. Other lenses in this same category are the O2optix by Ciba and Bausch & Lomb's PureVision.  

Another benefit of the silicone hydrogel lenses is the ability to wear overnight. Sleeping itself reduces the amount of oxygen to the cornea because the lid is closed and significantly reduces the atmospheric oxygen to the cornea. With the lid closed, the transparent cornea now must get its oxygen from the small blood vessels in the back of the lid. If you put a regular hydrogel contact lens between the cornea and the back of the lens, you severely reduce the oxygen to the cornea. This will lead to severe edema and possibly corneal inflammation. With the silicone hydrogel lenses, the oxygen flow is not interrupted so corneal integrity is not compromised.

Vistakon, maker of the Acuvue products, will introduce the Oasys lens beginning in August, 2005. This lens is marketed as: Meeting the Challenges of Today's Environments that Cause Eyes to Feel Tired and Dry. This lens has Hydraclear Plus technology, apparently a step up from just ordinary Hydraclear.

The silicone hydrogel lens has earned its designation as choice number one for new contact lens wearers. We have also switched many veteran wearers to the new lens material, particularly our patients who are finding some difficulty with comfort toward the end of the day.

Multifocal Contact Lenses

Every contact lens manufacturer has a multifocal or bifocal-type lens. Unfortunately, no manufacturer has a lens that is decisively better or meets patient expectations at any consistent level. The goal to be met is 20/20 vision in each eye at distance and 20/20 in each eye at near. This goal is obtainable approximately 10% of the time. Different brands may work better on some patients than others. The key is not to give up when the first pair of diagnostic lenses produce unfavorable results. Many times, no lens will meet the visual performance that is obtained with glasses. In this case, creativity is necessary.

Creativity may include fitting the dominant eye with a non-multifocal distance lens and fitting the non-dominant eye with a multifocal-type lens. Another creative method would be fitting the dominant eye with a multifocal lens with emphasis on distance vision. In this situation, the distance is fully corrected and a low bifocal power is prescribed so as not to interfere with the distance vision. As a general rule, for multifocal fitting of contact lenses, as you improve the near vision, you make the distance vision worse and vice versa. The non-dominant eye is fit with emphasis on near vision which means the distance vision will not be ideal in the near, non-dominant eye.

Multifocal lenses are not limited to soft lenses. Better vision and less overall cost is often achieved with gas permeable lenses. New designs in GP lenses are constantly improving both vision and comfort. While vision has certainly improved with the newer soft lenses, gas permeable lenses still surpass soft when it comes to best vision. Soft lenses still lead in overall comfort.

Success with multifocal soft lens fitting is very dependent on what visual tasks the wearer will need to meet. An accountant or someone that needs crisp reading vision all day, everyday, would probably not be your best candidate for multifocal contact lenses. A sales person, who occasionally has to refer to numbers or printed brochures, might be an ideal wearer of multifocal contact lenses.

Astigmatism-Correcting Lenses

Lenses that correct astigmatism are increasing in availability for a wide range of prescription types and materials. A welcome addition has been the introduction of the Biomedics 55 Toric lens for hyperopes (farsighted) patients. This has been a very stable, high-performing lens over the years, but only for the nearsighted. Also, a recent introduction in this category of lens has been the Acuvue Advance for Astigmatism with Hydraclear. 

 Multifocal-Astigmatism-Correcting Lenses

Are these lenses a breakthrough?  Can you see 20/20?  Well, not exactly, but these represent a step forward in the development of a lens that would be much desired by everyone over 45 who has astigmatism.  Like the regular multifocals, these lenses often need creativity to produce acceptable vision.  Hopefully, as manufacturing technology improves, these lenses will be a heavily-utilized means of vision correction.