Contact lens misuse: Water you thinking?

As we left the patient’s room in clinic, the attending physician I was shadowing turned to me and remarked, “Can you believe he was rinsing his contact case with tap water? No wonder he got Acanthamoeba." I smiled softly back and nodded. However, internally I was thinking, “I absolutely can believe that.” I, a medical student, a daughter of 2 physicians, and a contact wearer for more than a decade, had been rinsing my contact case with tap water after every use.

That moment in clinic stopped me cold. Not because of the patient, but because of myself. If I, with every advantage of education and a medical household, had been committing one of the most commonly cited contact lens hygiene errors for years without knowing it, what did that say about the way we educate contact lens wearers? And what did it say about the assumptions we make when we decide who needs to be told?

The universality of the problem

Contact lens misuse is not a fringe problem; it is widespread. CDC studies have found that upward of 80% to 99% of contact lens wearers report at least one risky practice, including sleeping in lenses, topping off solution, overwearing, and rinsing cases with tap water.¹

That last behavior is particularly consequential. Tap water, even municipal water that meets drinking standards, can harbor Acanthamoeba. This microscopic organism can cause Acanthamoeba keratitis (AK), a rare but devastating corneal infection that is difficult to diagnose early, resistant to many antimicrobials, and can progress to scarring and vision loss. Cases have been reported in otherwise healthy young patients whose only risk factor was rinsing their contact lens case with water, something they considered a responsible thing to do.² With an estimated 45 million contact lens wearers in the US, the scale of that risk is difficult to overstate.³

When the attending physician made that comment outside the patient’s room, the implicit message was clear: This patient should have known better. It is a sentiment that clinicians express, usually without malice, based on a reasonable intuition that some patients are higher risk for nonadherence than others. We learn to triage our counseling time. We direct our most thorough education toward patients we perceive as less informed, less engaged, or less health-literate.

The problem is that this triage is based on a flawed premise. Health literacy and behavioral adherence to contact lens hygiene have a weak and inconsistent relationship in the literature. Studies have found no significant protective effect of higher education or medical background on contact lens hygiene practices.⁴ A survey of health care workers found rates of lens misuse comparable to those in the general population.⁵ Knowing what Acanthamoeba is does not appear to be sufficient to change the habits formed when you are a teenager, being fit for your first pair of lenses.

My own case is illustrative of this. I had taken microbiology. I had studied infectious diseases and parasitology. I knew, in the abstract, that water harbors pathogens. None of that knowledge was ever connected, by any clinician, to the specific act of rinsing my contact case. The link simply was never made explicit, so I continued a habit I had formed at age 12 without a second thought.

For most contact lens wearers, hygiene education happens once briefly in adolescence, alongside a printed handout they likely did not read. The initial fitting is a cognitively busy appointment, and retention of hygiene instruction is predictably poor. Annual renewals, which follow, are transactional encounters focused on refraction, rarely structured to revisit habits. And why would patients raise it themselves? Years without an infection feel like confirmation that what they are doing is fine. The gap is not in patient intelligence or motivation. It is in the structure of how contact lens care is taught and never revisited.

The tap water problem has an additional layer: The behavior is intuitive. Water feels clean. Rinsing a case before adding fresh solution seems like sensible hygiene. The counterintuitive truth, that solution is safer than water, that water introduces rather than removes risk, is not something a patient arrives at independently. It has to be explained, not just listed as a rule. In 12 years of contact lens appointments, I cannot recall a single clinician mentioning AK or the dangers of water. That one missing explanation persisted as a gap in my practice for over a decade.

Needed counseling

The intervention is neither complex nor time-intensive. Brief, targeted counseling at the point of care—specific about which behaviors to avoid, clear about why—can meaningfully improve hygiene among contact lens wearers.⁶ The framing matters as much as the content. Counseling delivered reactively, after an error has been identified, carries an implicit judgment that can make patients defensive. A more effective approach presents re-education as universal: “Most people aren’t told this, so I like to mention it at every visit.” This removes the sting of correction and reflects the truth, because most people genuinely were not told.

Systemically, previsit questionnaires that screen for common hygiene behaviors can prompt the conversation before other clinical priorities crowd it out. For trainees such as myself, watching an attending physician model this kind of brief, nonjudgmental counseling offered routinely to every patient is a more lasting education than any lecture on AK pathophysiology.

I have often thought about that hallway moment. Not because the attending physician said anything wrong, but because of what my soft nod concealed: the recognition that I had been that patient, without knowing it, for over a decade. The patient in that room was not ignorant. He was simply never told, in the right way, at the right time. He was, in that sense, me.

As I move toward ophthalmology residency, I carry that moment as a reminder never to assume a patient’s medical literacy or prior knowledge. The most effective patient education is not corrective; it is proactive, specific, and offered to everyone, regardless of how educated or experienced they appear to be.

References

1. Cope JR, Collier SA, Rao MM, et al. Contact lens wearer demographics and risk behaviors for contact lens-related eye infections--United States, 2014. MMWR Morb Mortal Wkly Rep. 2015;64(32):865-870. doi:10.15585/mmwr.mm6432a2

2. Alreshidi SO, Vargas JM, Ahmad K, et al. Differentiation of acanthamoeba keratitis from other non-acanthamoeba keratitis: risk factors and clinical features. PloS One. 2024;19(3):e0299492. doi:10.1371/journal.pone.0299492

3. Konne NM, Collier SA, Spangler J, Cope JR. Healthy contact lens behaviors communicated by eye care providers and recalled by patients - United States, 2018. MMWR Morb Mortal Wkly Rep. 2019;68(32):693-697. doi:10.15585/mmwr.mm6832a2

4. Cardona G, Alonso S, Yela S. Compliance versus risk awareness with contact lens storage case hygiene and replacement. Optom Vis Sci. 2022;99(5):449-454. doi:10.1097/OPX.0000000000001881

5. Oruz O, Harbiyeli İİ, Erdem E, Yağmur M, Ateş EG. Attitudes and behaviors regarding compliance with contact lens wear and care among contact lens users at a university hospital in Turkey. Eye Contact Lens. 2024;50(10):426-431. doi:10.1097/ICL.0000000000001116

6. Lam D, Wagner H, Zimmerman AB, et al. Change in risk score and behaviors of soft contact lens wearers after targeted patient education. Eye Contact Lens. 2022;48(8):347-354. doi:10.1097/ICL.0000000000000900