Why wouldn’t you fit silicone hydrogels?

Silicone hydrogel contact lenses have now been around for about 5 1/2 years. Although their market penetration is higher in Australia than any other market in the world, they still only account for a low proportion of total contact lens sales.

Having lectured on silicone hydrogels and interacted with colleagues in Australia for the past few years, I hear many excuses for not fitting silicone hydrogels.

The most common excuse is that patients find them uncomfortable. Initial comfort is only an issue for previous wearers of conventional hydrogel lenses and is related to the modulus (rigidity) of the material. The higher the silicone content in the material, the higher the modulus and consequently the higher the oxygen transmissibility. I find if patients are warned about the initial “awareness” of the more rigid material, they adapt within the first few days of wear. Allowing patients to compare lenses with different moduli only highlights the difference in initial comfort. New wearers tend to adapt almost immediately since they have no previous experience with which to compare.

Another common excuse for not fitting silicone hydrogels is that they are too expensive for the patient. I find that patients who are successful with continuous wear are happy to pay the extra for the privilege, especially if it is broken down to a weekly or daily extra expense over conventional hydrogels. The extra expense is further offset by the reduced use of contact lens care products.

The recent release in Australia of two silicone hydrogels for daily wear has also helped address the cost issue. These silicone hydrogel products cost little more than conventional hydrogels and offer patients greatly improved physiological performance compared to hydrogels and end of day comfort.

The only legitimate excuse for not fitting silicone hydrogels is the limitation of parameters and designs currently available in these materials. This situation is now being addressed with the recent release of the two new designs mentioned above and two silicone hydrogel torics, which now allow practitioners to fit most astigmatic patients with lenses that provide superior physiological performance (Figure 1). A multifocal design is also currently being developed.

Figure 1 - click to enlarge

It is also important to recognise that there are some complications that may arise with certain patients which still need to be addressed by silicone hydrogel manufacturers. Some patients will experience an increase in the level of muco-lipid deposits, which may restrict continuous wear or even daily wear success. The higher modulus of silicone hydrogels may also induce contact lens induced papillary conjunctivitis (CLPC) in susceptible individuals. For these patients a lower modulus material or daily disposables may be the only contact lens solution at this time.

Figure 2 High myope daily wear - click to enlarge	Figure 3 High myope continuous wear - click to enlarge

In conclusion, there is no doubt that every suitable patient should be fitted with silicone hydrogels. Whether for daily wear (Figure 2) or continuous wear (Figure 3) , the superior physiological response and end of day comfort should make silicone hydrogels every contact lens practitioner’s first choice. Higher profit margins and greater patient satisfaction can only enhance the success of our contact lens practices.