Should you change from hydrogel to silicone hydrogel contact lenses

Why Are So Many New Lenses Made From Silicone Hydrogel

So you can see that optometrists are definitely favouring Silicone Hydrogel lenses over the regular hydrogel lenses most people are familiar with.

This data relates to both new contact lens fittings and contact lens refits - it highlights that regular hydrogel lenses are only fitted in just over 1 in four fittings, so, whether you are new to contact lenses or having a contact lens check-up, you are 3 times as likely to be fitted or refitted, with a silicone hydrogel lens. It’s not surprising then to see why so many contact lenses are now made of Silicone hydrogel.

Why Is My Optometrist Changing Me To Silicone Hydrogel Lenses 

A recent survey (2) of over 1000 independent and retail Eye Care Professionals in six countries showed that 43% agreed that existing Hydrogel contact lens wearers should be refitted with daily disposable Silicone Hydrogel lenses, even when there is no obvious clinical reason to do so. Only 20% of care professionals disagreed.

The exception was in the US where a similar percentage of Eye Care Professionals agreed as disagreed.

Figure 1 results show the extent of agreement shown in blue, or disagreement shown in red with the statement ‘I fit my daily disposable hydrogel wearers to daily disposable silicon hydrogel even when there is no clinical reason to do so’. Data is from 2022 for all markets except Russia, which is from 2021.

If You Are Successfully Wearing Regular Hydrogel Lenses Should You Swap To Silicone Hydrogel

One of the main reasons people need to drop out of contact lens wear is hypoxia-induced corneal swelling - not getting enough oxygen through to the eye. Several studies (3-5) have shown that silicone hydrogel contact lenses induce significantly less corneal swelling than regular hydrogel lenses when the eye is closed. This indicates that silicone hydrogel should be the contact lens of choice for extended wear or overnight contact lens wearers.

There is also evidence that silicone hydrogel contact lenses can reduce the risk of Corneal oxygen deficiency in high-powered plus or minus contact lenses, or any soft contact lens with a thicker centre or edge - for example, prism ballast toric lenses - even in daily wear lenses.

From the data presented so far, you can see that 26% of overall contact lens fittings are for hydrogel lenses, so some eye care professionals must still like hydrogel lenses. So why is this?

Short-term studies have shown that contact lens wearers with low to moderate prescriptions, who wear lenses only daily, show no evidence of ocular hypoxic compromise.
A partial double-masked study comparing three daily disposable hydrogel lenses and no-lens wear, showed no significant differences in topographical corneal swelling and bulbar limbal hyperemia (ocular irritation associated with dry eye disease (DED)) between the regular hydrogel contact lens and no lens wear after 8 hours (6)

Similarly, recent reports have indicated there is no evidence of ocular hypoxia compromise in the long-term wear of regular hydrogel daily disposable contact lenses. In fact, a comprehensive literature review in 2020 showed no signs of hypoxia after wearing hydrogel contact lenses for many years and suggested hydrogel contact lenses are an important option for daily contact lens wearers. (7)

Conclusion

Evidence from recent literature and studies shows that there is minimal impact on the cornea with long-term daily wear of regular hydrogel lenses for people with low to moderate prescriptions. Also, due to the lack of substantial evidence of the difference in comfort levels between hydrogel and silicone hydrogel lenses, or the difference in risk of developing serious complications such as microbial keratitis (16), it would suggest that if you are wearing hydrogel contact lenses successfully, there is no rush to change to silicone hydrogel lenses.
However, we advise not just swapping from silicone hydrogel lenses to hydrogel lenses if you are not happy with silicone hydrogel lenses, whether it’s due to comfort levels or price, always speak to your eye care professional to see why they have recommended silicone hydrogel lenses for you. It may be that Silicone Hydrogel contact lenses are the best option for you.

References

1. Morgen PB, et al. International Contact Lens Prescribing in 2021. CL Spectrum 2022;37:32-8.
2. Johnson & Johnson Vision Care. Online survey of 1028 Eye Care Professionals across the United States, United Kingdom, Russia, China, Japan and South Korea. JJV data on file; 2021(Russia) and 2022 (other markets).
3. Fonn D, du Toit R, Simpson Tl, Vega JA, Situ P. Chalmers RL, Sympathetic swelling response of the control eye to soft lenses in the other eye. Invest Ophthalmol Vis Sci 1999; 40:3116-21.
4. Bullimore M, Nguyen M, Bozic J, Mitchell G. Overnight corneal swelling with 7-day Continuous Wear of Soft Contact Lenses. Investigative Ophthalmology & Visual Science 2002;43:3100
5. Fonn DM, Simpson T, Situ P. Confirmation of a yolked corneal swelling response between the test and contralateral control eye. Optom Vis Sci 2004;81(125):30.
6. Moezzi Am, Varikooty J, Schulze M, Ngo W, Lorenz KO, Boree D, Jones LW. Corneal Swelling with Cosmetic etafilcon A Lenses versus No Lens Wear. Optom Vis Sci 2016;93:619-28.
7. Efron N, Brennan NA, Chalmers RL, Jones L, Lau C, Morgan PB, Nichols JJ, Szczotka-Flynn LB, Wilcox MD. Thirty years of "quiet eye" with etafilcon A contact lenses. Contact Lens and Anterior Eye 2020;43:285-97.