contact lenses

The More Things Change, The More They Stay Complicated

What research tells us about how we should manage CL complications.

FRANK CELIA
Contributing editor

As soft contact lenses enter their fourth decade of widespread clinical use, the modality continues to be safe and effective, popular with patients and a cornerstone of the optometric profession.

Yet some of the problems associated with wearing contact lenses appear stubbornly resistant to improvement. Although they transmit more oxygen to the cornea than ever before, the incidence of corneal ulcers refuses to budge.¹ Infection rates associated with extended wear lenses remain pretty much the same as in the waning days of the Cold War², and the widespread popularity of daily disposables failed to spark the corneal health boom for which so many had hoped.

While contact lens complications have never approached anything near rampant, the fact that complications persist means practitioners and patients must stay on guard for — and take steps to prevent — conditions that, however rare and however asymptomatic, could ultimately threaten vision.

Call to arms

A study published in Eye & Contact Lens last summer found that about 50% of eyes in a large cohort of lens wearers demonstrated at least one complication.³ This was an increase over the conclusions of a 1996 study, which put that figure at 39%.⁴

The 50% finding is a headline grabber. Contact lens experts consider the study well-done and meticulous, its investigators held in high regard, and the data have fostered discussion in optometry circles. Experts note, however, the criteria for complications were fairly broad, and the researchers reported mostly mild, asymptomatic problems and only one case of non-vision threatening microbial keratitis among the 846 eyes studied. Moreover, the half-cohort complication rate has precedent: a 1987 study approximated it.⁵ Nevertheless, many view last year's data as a call to arms, especially coming in the wake of the 2006-2007 contact lens solution recalls that occurred as a result of microbial infection outbreaks of Fusarium keratitis and Acanthamoeba keratitis.

“This is one of the best overall contact lens studies I've seen in a long time,” says Jack Schaeffer, O.D., of the Schaeffer Eye Center in Birmingham, Ala. “We, as doctors, have to control a proper and timely medical follow-up procedure so we can monitor and prevent noncompliance among (contact lens) patients. This (study) emphasizes and supports how important that follow-up care is.”

FDA studies have shown that no one solution on the market can kill 100% of Acanthamoeba, except two-step peroxide, which is now so little used that retailers seldom carry it, Dr. Schaeffer adds. Eye care is no more immune to the dangers of “super bugs” created by decades of antibiotic use than any other medical field, he cautions. Methicillin-resistant Staphylococcus aureus (MRSA) has long been reported in ocular surgery settings, and it's not unreasonable to speculate another solutions-related outbreak could occur. “We must always bear in mind that contact lenses are doctor-prescribed, medical vision-correction devices, and this study reinforces that fact,” Dr. Schaeffer says.

Lens choices

Choosing a contact lens remains largely a matter of a doctor's preference. No one lens material or design has proven a silver bullet. Thus, practitioners tend to rely on logic, anecdotal evidence and a patient's specific needs when choosing a lens material and design. For example, for years, silicone hydrogel lenses have been thought to induce slightly higher rates of giant papillary conjunctivitis (GPC) than traditional hydrogels, and although this has yet to be proved in clinical trials, many optometrists regard it as fact. It is logically assumed silicone hydrogels, being more lipophilic and hydrophobic, cause greater abrasion to giant papillary nodules.

Although silicone hydrogels may have fallen short of the industry's highest hopes, they do offer advantages, and they continue to gain market share.¹ William D. Townsend, O.D., F.A.A.O., in private practice in Canyon, Texas, says the percentage of his patients wearing silicone hydrogel contact lenses has been increasing for years and now stands at about 70% of his contact lens practice. The material excels at oxygen transmissibility and, thus, is particularly beneficial for patients with thicker lenses. “After a long period of chronic hypoxia (induced by hydrogel lens wear) certain individuals experience loss of limbal stem cells, putting them at risk for developing conjunctivalization,” Dr. Townsend says.

Not all patients find silicone hydrogel contact lenses comfortable, however. Among traditional hydrogels, Dr. Townsend draws a distinction between nonionic and ionic materials, with ionic lenses having been shown four to five times more likely to become coated with debris.⁶ For those patients who don't prefer silicone hydrogel lenses, Dr. Townsend will fit them in a nonionic hydrogel lens, especially if he sees “someone who has a lot of debris in his tears, or if he has had problems in the past with coating.”

Dianne Anderson, O.D., F.A.A.O., of DuPage Medical Group Eye Specialists, Naperville, Ill., follows these guidelines when matching a lens to a patient's needs: “If a patient is prone to papillae or GPC, a thinner, lower-modulus frequent-replacement lens will minimize lid friction and protein deposition. In a patient prone to neo-vascularization, daily wear (as opposed to extended wear) silicone hydrogels will allow more oxygen to the cornea. In patients prone to infiltrates and ulcers, daily disposables will ensure that a clean lens is worn each day.”

Contracting for compliance

With successful contact lens wear so dependent on a patient's behavior, it's difficult to over-stress the importance of compliance to safety standards, which includes showing up at the office for regularly scheduled checkups. Dr. Townsend insists new contact lens patients sign a contract, detailing exactly which care regimen he has prescribed and a pledge from the patient to contact his office if complications arise. Dr. Townsend sees established, healthy contact lens patients once a year and new wearers or patients experiencing complications every six months. If a patient consistently flouts his wearing schedule, misses appointments or otherwise proves noncompliant, Dr. Townsend will consider “firing” that patient. “I tell the patient, ‘I can't be your doctor anymore’ and send him a letter to that effect,” he explains. “If you do that two or three times, word gets around.”

Another tactic to keep patients on the straight-and-narrow is to show them vivid color images of severe contact lens complications in all their gory detail. “We don't want brave patients,” Dr. Townsend says. “We want cowardly ones.”

Regardless of the instructions on the bottle, most doctors instruct patients who use multipurpose solutions to rub their lenses during cleaning. They also emphasize that patients need to wash their hands any time they handle their lenses. “One positive aspect of the swine flu virus scare is to underscore the importance of hand-washing for the American people,” Dr. Townsend notes.

Perhaps the most significant trend in contact lens complication management is the growing acknowledgement of solution-material interactions. Factors such as contact lens water content, pore size of the contact lens matrix, ionic charge and material molecule size can cause certain material-solution combinations to interact poorly. Practitioners stress the value of specifically prescribing a solution to each patient and making certain your advice is followed.

Last summer's Eye & Contact Lens study found the highest percentage of solution complications occurred in patients who used generic and private-label solutions. Other research has concluded that 16% of patients switch from the brand of solution recommended by their optometrists.⁷ The struggling economy may provide additional incentives for patients to switch from a solution recommended by the doctor to less expensive generic solutions.

Regular follow-up

Even when contact lens patients follow their doctors' recommendations to the letter, lens-related complications still occasionally arise. When diagnosed early, however, they can be managed effectively. An annual comprehensive clinical evaluation, including a corneal staining assessment, is critical.

“Staining is a nuisance,” Dr. Townsend admits, but he notes it provides vital information that cannot be obtained from any other test. To streamline the process at his practice, he keeps compounded lissamine green staining fluid in sterile syringes with micro filter tips. “The drops go through the filter, and you get the same concentration every time,” he says. “The syringes last about a month in each room.”

Practitioners should be alert for follicular conjunctivitis, which is often a sign of solution-related hypersensitivity or toxicity, according to Dr. Townsend. Avoid shortcuts in clinical evaluation, he adds, because patients with moderate to severe contact lens complications can be asymptomatic. “I've had patients say they were feeling fine when they had blood vessels growing a millimeter and a half into their corneas,” he says.

In the current media environment, clinical care counts more than ever, notes Brian Chou, O.D., F.A.A.O., of Carmel Mountain Vision Care in San Diego: “Consumers need to be aware of the value of professional services, especially in this age when certain contact lens manufacturers are trying to portray their products as something they can prescribe themselves— i.e., ‘Just ask your doctor for a free trial pair!’” OM

1. Mah-Sadorra, JH, et al. Trends in Contact Lens-Related Corneal Ulcers. Cornea. Jan. 2005; Vol 24(1):51–58.
2. Stapleton F, et al. The incidence of contact lens realted microbial keratitis in Australia. Ophthalmology 2008;115:1655–1662.
3. Forister JF, Forister EF, Yeung KK, et al. Prevalence of contact lens-related complications: UCLA contact lens study. Eye Contact Lens. 2009;4:176–180.
4. Keech P, Ichikawa L, Barlow W. A prospective study of contact lens complications in a managed care setting. Optom Vis Sci. 1996;73:653–658.
5. Cunha M, Thomassen TS, Cohen EJ, Genvert GI, Arentsen JJ, Laibson PR. Complications associated with soft contact lens use. CLAO J. 1987;13:107–111.
6. Sariri R. Protein interaction with hydrogel contact lenses. Journal of Applied Biomaterials & Biomechanics. 2004;2:1–19.
7. Chun MW, Weissman BA. Compliance in contact lens care. Am J Optom Physiol Opt. 1987;64:274–276.