Dr. Robin Chalmers has studied and published on contact lens complications for more than 20 years. She is very involved with the American Academy of Optometry and is an Assistant Editor for Contact Lens & Anterior Eye, the journal of the British Contact Lens Association.
Epidemiology of contact lens-induced infiltrates: an updated review. Steele KR, Szczotka-Flynn L. Clin Exp Optom. 2017, 100(5):473-481.
Why should
clinicians be interested in an updated review of contact lens induced corneal
infiltrative events (CIEs) and how does increased understanding of CIEs help in
clinical practice? First of all, the
review’s conclusion begins with a strong statement about how daily disposable
(DD) lenses have reduced the incidence of CIEs and a call to action for
eye care practitioners to “disseminate information already known about the
epidemiology of CIEs to at-risk individuals”.
So, let’s walk through the information presented in this manuscript
section by section.
Incidence and Classification of CIEs
The incidence
of any condition is dependent on how the condition is classified in a
study. Contact lens wearers can present
with a painful adverse event that we classify as a CIE or they can come in for
a routine checkup with no symptoms and have milder CIEs present. The incidence of symptomatic CIEs in the
reviewed studies ranges from about 2.5% to 6% per year of wear for reusable
soft contact lenses and is much lower for DD lenses at less than 0.4% per
year.
In your
clinical practice, the CIE incidence among your patients will depend on the
types of patients you fit and the types of lenses that you prescribe for those
patients. For example, if you allow patients
to sleep overnight in their soft lenses, or don’t actively discourage this
practice at each follow-up visit, you will be treating more CIEs, very likely
more serious CIEs, and have patients that are also at higher risk for sight-threatening
microbial keratitis. This is not a good
plan. On the other hand, if you use this
information to discuss with patients the clinical evidence of a 10 times lower
CIE rate with DD lenses, then you can help many types of patients avoid
CIEs. The patient is in your chair to
hear what you know about the safest way that they can wear contact lenses. The Steele review paper gives you tools for
this discussion.
The modified Aasuri CIE classification system shown in Table 2 of the review is very useful in practice to provide a visit-by-visit scoring of the severity of the CIE. Only by carefully documenting the features in the scheme can the clinician precisely determine whether the patient is improving over time with the treatment plan. The system assigns points for patient symptoms, lid swelling, conjunctival redness, the shape of the infiltrate, the size of the largest infiltrate, the number of infiltrates, fluorescein staining, corneal edema around the site, endothelial debris, hypopyon and whether discontinuing lens wear improves the situation. The utility of this scoring grid is that it can describe the full range of events from the asymptomatic infiltrates that may be observed at routine visits, to the all-important differential diagnosis between a CIE and an infectious microbial keratitis. (Table 2 in paper available here. Free access, available online and as a pdf)
Operationally
in a clinical setting, if your electronic medical record does not have the
ability to capture the Aasuri score, it could be scored on a separate grid and
the score summarized in a comments section.
Filling out the score step by step also helps the clinician make sure
that they have considered all of these features that can indicate a
non-infectious inflammatory CIE event or point to an infectious form of keratitis. Some items like lid swelling and corneal
edema may be overlooked but are important indications of a possible microbial
keratitis, if present.
Review of Risk Factors
Epidemiology studies patterns of disease in large populations, but clinicians treat one patient at a time. Understanding the risk factors for CIEs will help practitioners decide where their patient fits into the at-risk population of contact lens wearers. Table 3 of the Steele review gives a good synopsis of risk factors for CIEs. Salient factors include patient age, sex, high refractive error, prior history of eye events, smoking, overnight wear, use of reusable (not DD) lenses, use of a multi-purpose lens care system, silicone hydrogel lens wear and eye redness when they are not having an adverse event. The patient-related factors cannot be changed, but the way they wear lenses (no overnight wear) and the choice of lenses can be changed to lower the risk of CIEs. The only risk factor from this literature that a clinician can’t assess directly is whether the patient has a high level of bacterial bioburden on their lids. This list is very user friendly in a clinical setting. (Table 3 in paper available here. Free access, available online and as a pdf)
Remember, each
of these risk factors usually stack on top of each other, so a person aged 20
who smokes and wears their reusable lenses overnight will have a much higher
risk of problems than a non-smoker in their late 30s wearing DD lenses. In discussions with patients, point out to
them that you have taken into consideration of their personal risk factors in
order to make the best prescribing recommendation on how to avoid problems with
their lens wear. A person can’t change
being a 20 year old, but can choose DD lenses as a way to wear lenses in the
healthiest way.
It is also
important to note that the largest single risk factor for the development of
CIEs is the use of reusable contact lenses, which account for a 12.5 times
higher risk compared to wearing DD lenses.
As Steele discusses, this may be due to contamination of contact lens
storage cases or interactions with lens care systems, but regardless of the
reason, patients who use their DD lenses and discard them after each use will
reduce their chance of a CIE by an order of magnitude. Recently, contact lens companies have vastly
expanded the range of lens prescriptions available in the DD replacement
modality to include all types of toric, multifocal and extended range powers. The vast majority of patients can be
corrected with this type of lenses nowadays.
One factor that
is not presented in Table 3 is the exposure of soft contact lenses to
water. In addition to being a risk
factor for the development of Acanthamoeba keratitis, the Contact Lens
Assessment in Youth (CLAY) study team has shown that showering while wearing
soft lenses increases the risk of CIEs by 3.1 times, rinsing lenses in tap
water and any other water exposure each double the risk. Zimmerman has published results of CLAY’s
work in collaboration with the US Center for Disease Control and Prevention
that shows that patients are largely ignorant of water use as a risk for
contact lens complications; about 90% of soft lens wearers shower and 60% swim
while wearing lenses. This exposure to
tap water is even worse for rigid lens wearers, 90% rinse lenses with tap water
and many shower and swim while wearing their lenses as well. Talk to your patients during each after care
visit about how they can reduce their exposure to water during lens wear.
In summary,
Steele’s well-written and complete review of the epidemiology of contact
lens-induced corneal infiltrates will give you great tools to help counsel your
existing and new contact lens wearers toward a successful and safe wearing
experience. It will also help highlight
why your personalized care is a necessary part of their eye care.
