CONTACT LENS MANAGEMENT TRENDS 2010
Heading off Trouble
What you need to consider about microbial keratitis, giant papillary conjunctivitis and contact lens-induced dry eye
By Victor L. Caparas, MD, MPH
It is estimated that 100 to 125 million people wear contact lenses worldwide. However, a recent survey of 572 patients at UCLA showed that about 50% of their eyes experienced at least one contact lens-related complication.1 Outbreaks of Acanthamoeba and Fusarium keratitis infection associated with recalled multipurpose contact lens solutions 3 to 4 years ago also remind us of the importance of quickly recognizing and managing potentially dangerous problems.
To help you avoid contact lens drop out in your patients because of these and other problems, I'll review the implications of the three major disruptors of safe and comfortable contact lens wear.
CONTACT LENS-RELATED MICROBIAL KERATITIS
According to one study in Taiwan over a 10-year period, 43% of 467 cases of microbial keratitis were related to contact lens wear. The most frequent cause was Pseudomonas, at 38%.2
This should come as no surprise. Some of the defenses of the eye are compromised when a patient is wearing contact lenses; for example, the interaction between the epithelial surface and the lid is altered, preventing the wiping action of the lid (Figures 1 and 2).3,4 Tear exchange is reduced markedly, creating a stagnant pool of tears on the cornea posterior to the contact lens.5 Contact lens wear reduces the thickness of the epithelium, decreases the rate of cell turnover and desquamation, and increases the ability of bacteria to adhere to epithelial cells.6
|Figure 1. Painful, red eye|
■ 22-year-old female, working on a computer 12 hours a day.
■ Occasionally sleeps in monthly disposable soft lens
■ Awakes with red, painful right eye. Copious tearing, photophobia. Yellowish, pus-like discharge
■ VA: 20/200
■ Moxifloxacin eye drops started
|Figure 2. Painful, red eye|
■ 5 days of antibiotic treatment
■ Greatly decreased pain, photophobia, less redness no discharge
■ VA 20/50
■ lesion resolving
Reduced corneal sensitivity can blunt reflex tearing and blinking responses.7 Contact lenses also cause breaks in the epithelium (such as punctate erosions, abrasions, and splits), allowing direct access of pathogens to the stroma.8-9 The epithelium of the contact lens wearer is thinner, less sensitive, and relatively hypoxic, reducing the ability of the epithelium to repair itself and repel invading organisms.10
Extended wear hydrogel and silicone hydrogel lenses have been associated with the highest incidence of microbial keratitis, having been reported in 145 and 119 times per 10,000 wearers per year, respectively, in one study. The numbers for daily hydrogel and daily disposables were 20 and 14, respectively.11
MOST SERIOUS KERATITIS
Microbial keratitis due to gram-negative organisms, such as Pseudomonas, in addition to other organisms, such as Acanthamoeba, can increase the risk of vision loss and are associated with the longest duration of disease and most expensive treatment, especially when lesions are centrally located.12 Be sure your patients understand the importance of caring for contacts properly and contacting your office at the first sign of these problems.13
Factors that may contribute to these infections include inadequacy of some multipurpose solutions against key pathogens, poor hygiene, and poor compliance. Growing clinical thought also supports the re-establishment of a digital rub component to multipurpose solution lens care systems to help in this regard.14
PROMISES OF DISPOSABLE, HIGH DK LENSES
One of the original thoughts behind daily disposable contact lenses was that they would eliminate the need for contact lens care and storage and, therefore, contamination and risk of infection.15 However, one recent study has shown that lens wearers in a daily disposable lens had a slightly higher risk of microbial keratitis.16
Likewise, one of the thoughts behind the development of silicone hydrogel materials was that they would reduce corneal hypoxia, decreasing the risk of infection. However, silicone hydrogel lenses can still be associated with the development of microbial keratitis.12
To avoid infection, again, it is critical to remain vigilant in properly instructing your patients in lens handling, lens care, lens case hygiene and replacement.
GIANT PAPILLARY CONJUNCTIVITIS
Although microbial keratitis is the most serious contact lens complication, we also need to be mindful of a more frequent complication, giant papillary conjunctivitis (GPC), which some studies suggest affects up to 45% of all contact lens wearers.1,17 (Figure 3)
Figure 3. Pathogenesis of Contact Lens-Related GPC
Of all cases, one study suggests that approximately 85% involved soft lenses and 15% involved rigid lenses.18 The frequency is 34% among extended-wear conventional lens wearers vs. 5% in extended-wear disposable lenses.19 A 2% to 14% frequency has been reported among users of high DK silicone hydrogel lenses.20 Onset of disease after fitting is most frequently 10 to 20 months among soft lens wearers, 21 months among GP wearers, and 90 months among PMMA wearers.19
The papillae of patients with GPC are characterized by telangiectatic blood vessels, forming first in the zones of tarsal conjunctiva near the upper margin of the tarsal plate in soft lens wear and first in the zones of the tarsal conjunctiva nearest the eyelid margin in GP wear.21-22
You may see two types of papillae, including generalized, associated with hydrogel PC, or localized, confined to one to two areas near the lid margin23 (Figure 4).
The clinical factors associated with GPC include allergies, systemic medications, debris on the contact lens surface, contact lens coatings and lens replacement schedule.1,24 Lenses with high water content tend to have more deposits, creating more severe symptoms, while ionic polymers tend to have greater proteinaceous deposits and less severe symptoms.17,25
To manage GPC, discontinue contact lens wear until inflammation subsides. (The papillae will take longer.) You can also consider prescribing an antihistamine mast cell stabilizer such as olopatadine (Patanol, Alcon) and corticosteroid drops on a short-term basis. Lubricants will improve lubricity (decreasing friction) and dilute/wash out inflammatory mediators.
Most patients can return to contact lens wear following anti-inflammatory treatment. Shift to frequent replacement soft high DK silicone hydrogels.
WHAT'S AT STAKE
If we take an enlightened approach in these three areas—minimizing risks of infection, recognizing and treating GPC, and managing dry eye symptoms (Figure 5)—we can keep more of our patients safe and comfortable, which will go a long way in keeping them from dropping out. CLS
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