Risks Associated With Contact Lens Wear
Medscape: What risks are associated with contact lens wear? Do certain adverse events only occur with particular types of contact lenses (eg, soft vs rigid gas permeable, or extended wear vs disposable) or materials used?
Dr. Lepri: The risks associated with contact lens wear are the same for all types of contact lenses (eg, rigid, soft, extended wear, daily wear) that are worn. Wearing contact lenses increases the risk for several serious conditions, including eye infections and corneal ulcers. These conditions can develop quickly; in rare cases, they can even result in blindness. The degree of risk is different for daily wear vs extended/overnight wear, as well as for different types of lens materials.
Risk is defined by the most serious adverse event that can occur, which in the case of contact lenses is microbial keratitis. A prospective study was conducted to determine the incidence of contact lens-related microbial keratitis in Australia. The study evaluated the incidence of microbial keratitis, as well as the rates of microbial keratitis among various modes of contact lens wear (daily wear, daily disposable, and extended wear) and types of contact lens materials (conventional hydrogel, silicone hydrogel, and gas permeable). The investigators reported on 151 cases of contact lens-related microbial keratitis; of the ophthalmic practitioners who participated in this study, 81% responded. The rates obtained were based on a denominator of 10,000 contact lens wearers.
They found that 7.5% of wearers were using daily disposable contact lenses and 9.3% were using silicone hydrogel contact lenses. The annual incidence of all contact lens-related microbial keratitis was 4.8 per 10,000 wearers. The annual incidence of moderate or severe culture-proven keratitis was 0.9 in daily disposable contact lens users, 3.1 in daily-wear soft contact lens users, 4.5 in daily-wear silicone hydrogel contact lens users, 11.7 in extended-wear soft contact lens users, and 19.3 in extended-wear silicone hydrogel contact lens users.
Vision loss after microbial keratitis occurred more frequently with extended-wear soft contact lenses compared with extended-wear silicone hydrogel contact lenses. Microbial keratitis with extended-wear silicone hydrogel contact lens use seemed to be associated with a longer duration of continuous use than in extended-wear soft contact lens use;, meaning that study participants were wearing silicone hydrogel lenses longer before they developed microbial keratitis compared with those who were wearing conventional soft contact lenses.
Vision loss from microbial keratitis may be permanent. It all depends on when the diagnosis is made. If it is caught early and diagnosed properly followed by treatment, there may be no ulceration or scarring. (The scarring that develops from the corneal ulcer can cause permanent vision loss.) If the ulcer is centrally located in the cornea, permanent vision loss may occur, depending on how deep and invasive the ulcer is.
The important thing to convey is that despite the low rates obtained in a study, we have to be concerned about the individual contact lens wearer. If it happens to you, the rate is 100%! One can develop microbial keratitis as soon as the first night of wearing an extended-wear lens. It depends on the individual, the immune system, the natural flora in the tear film, and personal hygiene habits. All of those factors could come into play. So while it's not common that microbial keratitis happens, the potential exists.
You could wear contact lenses for many years and never have a problem, and then suddenly develop microbial keratitis. Diligence regarding proper care and hygiene and regular follow-up with an eye care provider is critical to reduce the risk for any serious adverse event.
Medscape: What symptoms should clinicians be aware of in patients presenting with eye complaints due to contact lenses? Which ones warrant referral to an eye care professional?
Dr. Lepri: There are signs and there are symptoms. The signs are what the clinician observes, and the symptoms are the patient's complaints.
The first symptom that clinicians should be aware of is discomfort, and that's on a continuum, ranging from the patient feeling uncomfortable to actually feeling pain. Discomfort may be described differently depending on the individual. What is one person's discomfort might be someone else's pain. Nevertheless, it should not be ignored. Patients could have excessive tearing or other discharge. They could have excessive sensitivity to light. They may have an itching, burning, or gritty feeling in the eye.
Marked redness -- or any redness for that matter, but especially if it's marked redness -- is definitely a flag. Blurred vision and any swelling in and around the eye, including the eyelids, warrant attention and could indicate a serious infection. For a primary care provider or an emergency department physician with no ophthalmic backup, any one or more of these signs or symptoms warrant referral to an eye care professional.
Medscape: Are there any strategies that can be initiated by the non-eye care professionals before referral?
Dr. Lepri: I definitely think a referral to an eye care professional is needed, and I would like to explain why we think that referrals are called for in these cases. Most patients initially present with eye problems to their primary care provider or to an emergency department. Unfortunately, staffing and equipment in emergency settings vary greatly. Some have on-call eye care professionals and equipment specifically designed for an ophthalmic examination, whereas others have general medical staff and no ophthalmic equipment. You cannot determine the nature of a problem that develops merely by observing the patient with the naked eye. The appropriate equipment and ability to use it are essential for diagnosis.
Eye care professionals use a biomicroscope (slit lamp) to examine the anterior segment, cornea, and conjunctiva. Biomicroscopic examination is absolutely necessary to make an accurate diagnosis and to establish an early, effective treatment regimen.
The typical presentation may be a red eye, and a red eye is a general sign telling you that something is wrong but not exactly what is wrong; it can be associated with many different causes. It is important to remember that not all red eyes are the same. Specific medical testing is needed to make a diagnosis. Patients seek medical care at different stages of disease development, so one cannot know to what level a condition has progressed in a red eye.
Red eyes are often misdiagnosed. For example, one may think it is a simple case of pink eye when, in fact, it could be something more serious, such as the early stages of a corneal ulcer resulting from microbial keratitis. Therefore, it is imperative to consult an eye care professional as soon as possible. This applies to any patient with a red eye who shows up in the emergency department or to a primary care provider, not just those who wear contact lenses.
Non-eye care professionals should use the following steps:
If the contact lenses are still in the patient's eyes, remove them immediately. Do not put them back in the eye.
Do not throw away the contact lenses. Store them in the case and have the patient take them to his or her eye care professional. The eye care professional may want to use the lenses to determine the cause of the symptoms by examining or culturing them to identify a potential microorganism causing an infection. This is critical for timely and accurate treatment.
Consult an eye care provider or refer the patient to see an eye care provider the same day or by the next day.
Medscape: What information might be relevant to report to the FDA in the case of an adverse event, such as an infection-causing microorganism?
Dr. Lepri: We're going to assume now that the patient has been referred to an eye care professional. Whenever an adverse event is detected, particularly associated with contact lens wear, it should be filed through the FDA's MedWatch system. There are a specific set of questions for ophthalmic events related to contact lenses, and they are tailored specifically for the type of information we need. Certainly, if an eye care practitioner has obtained a culture and sensitivity and has found the causative agent, then that would be included in the report.
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Cite this: Contact Lenses: The Risks You Need to Know - Medscape - Oct 24, 2012.