Infectious keratitis in contact lens users and after LASIK
The article by Masters, Kocak and Waite(1) published in January´s issue of the Journal of Cataract and Refractive Surgery was very much needed and very much welcome.
This article is a methaanalysis of the risk of corneal keratitis in different types of contact lenses and LASIK.
Articles about contact lens infectious keratitis were included if an annualized incidence could be inferred with the data of the article, if the keratitis were classified according to the type of contact lens used and if each subcategory had at least 1000 instances. Studies about corneal keratitis associated with LASIK were included if they also had at least 1000 instances and viral keratitis could be differentiated from bacterial keratitis.
There were 9 contact lens-associated corneal infectious keratitis articles included, by Poggio (1989)(2), MacRae (1991)(3), Nilsson (1994)(4), Cheng (1999)(5), Seal (1999)(6), Lam (2002)(7), Morgan (2004)(8), Schein (2005)(9) and Stapleton (2008)(10); and 8 LASIK-associated corneal infectious keratitis articles, by Lin (1999)(11), Stulting (1999)(12), Solomon (2003)(13), Hammond (2005)(14), Sun (2005)(15), de Oliveira (2006)(16), Moshirfar (2007)(17), Llovet (2010) and Ortega-Usobiaga (2015).
Results show that the overall mean annual incidence of corneal infections in the different groups is as follows:
– soft daily contact lenses: 3/10000
– extended wear contact lenses 17/10000
– rigid gas-permeable contact lenses 1/10000
– LASIK 5/10000
If we compare the differences between the most commonly used contact lens type nowadays, the soft daily, and LASIK, we would have:
If a person is wearing contact lenses for only one year, the possibility of getting a corneal infection is lower than if the same person undergoes LASIK treatment (3/1000 vs 5/1000) although the difference is not statistically significant (p = 0,0609).
As LASIK treatment only implies a one-time possibility of infection and the possibility of infections in a contact lens user increases every year, if the same person is using the same type of contact lenses for 2 years, the possibility of acquiring a corneal infection is already superior to the possibility of getting an infection undergoing LASIK (6/10000 vs 5/10000). At 5 years time, the comparison is worse (contact lens (15/10000 vs 5/10000, p < 0,001) and it worsens over the years, being at 10 years of soft daily contact lens wear 30/10000 vs 5/10000, p < 0,001.
In the last few years we have seen an increase of use of extended-wear contact lenses. These contact lenses are used during the night or even day and night. With these type of lenses, the possibility of an infection is multiplied by 8,5 when we compared with standard soft daily contact lenses. At one year, the possibility of an infection is 17/10000 and increases linearly every year. If we compare this possibility with the possibility of an infection after LASIK, we see that it is more than 5 times possible at one year, and it increases with years of use.
The study also concludes something that it is also known: out of all the different types of contact lenses, the one with the least possibility of being associated to a corneal infection is the rigid gas-permeable (RGP). The possibility of an infection with these lenses is 1/10000 per year. At 5 years of use, the possibilities of an infection are the same between using RGP lenses and undergoing LASIK.
The risk for infectious keratitis associated to the use of contact lenses is, according to this study, relatively high, and increases over the time of use. With only 2 years of contact lens use, this risk is already higher than the one associated to undergoing LASIK.
LASIK is a very regulated procedure. It is performed by qualified professionals in a specific setting and requires of a written consent signed by patient and professionals. Hospitals or clinics providing LASIK treatment are prepared to deal with any complications associated with the procedure.
Contact lens fitting should require the same: qualified professionals (I won’t enter in which type of qualifications), a written consent with all the pertinent potential complications mentioned, professionals trained to deal with complications if the law of their country allow them to treat patients or a referral center appointed by contract to solve any problems that may arise with the use of contact lenses. This is a matter, of course, to be addressed by Health Authorities.
1- Masters J, Kocak M, Waite A. J Cataract Refract Surg 2017; 43:67–73
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