Management of Contact Lens-Associated or Lens-Induced Pathology
Ron Melton
Randall Thomas
▪ INTRODUCTION
Many contact lens wearers experience years of successful wear with no complications associated with or induced by contact lens wear. However, contact lens wearers can experience ocular complications that are related to the type of lens, the wearing schedule, the solutions they are using or not using, self-inoculation of bacteria from handling of the lens, the case or expired solution, deposits on the lens, hypoxia from the lens, a foreign body trapped by the lens, or something totally nonrelated to contact lens wear, such as lid disease, dry eyes, and nonrelated anterior segment disease. This chapter will address ophthalmic pharmaceuticals that can help restore afflicted tissues to normal.
▪ ANTIBIOTICS
Antibiotics can be overused with the contact lens patient. As red eyes are more likely to be inflammatory than infectious, prescribing an antibiotic only because the practitioner is unsure of the diagnosis of the red eye does not justify its use. The most common symptom/clinical sign to warrant antibiotic use is an acute mucopurulent discharge. However, there are conditions in contact lens wear that require antibiotic treatment. The most common contact lens-associated complications that require the use of antibiotics are infectious keratitis (corneal ulcers), corneal abrasion, bacterial conjunctivitis, blepharitis, and hordeola.
Sodium Sulfacetamide
Sulfa drugs are bacteriostatic, meaning they interfere with bacterial replication, in this case by inhibiting folic acid production. Sulfa drugs are broad spectrum; however, many staphylococcal and Pseudomonas species are resistant to them. In addition, many patients are allergic to sulfa drugs. Sulfa drugs are available in both solution (10%, 15%, and 30%) and ointment (10%) forms. These drugs are produced by various companies. Because of the bacterial resistance and allergic reactions, sulfa drugs are rarely used by eye care practitioners to treat contact lens patients.
Bacitracin
Bacitracin is bacteriocidal, meaning it kills the bacteria. It achieves this by destroying the cell wall of the bacteria. Primarily, it is most effective against gram-positive bacteria. Bacitracin is available only in ointment form. It is most effective in treating moderate to advanced staphylococcal blepharitis in combination with aggressive lid hygiene. The recommended treatment regimen for bacitracin would be to prescribe it 1 to 2 weeks to be used on the lid margins at bedtime.
Bacitracin and Polymyxin B
A combination of bacitracin and polymyxin B provides the excellent gram-positive effect of bacitracin with the potency of polymyxin B on gram-negative organisms (including Pseudomonas). Polymyxin B is bacteriocidal by destroying cell membranes. It is marketed under the name Polysporin (Monarch Pharmaceuticals) and is available in generic forms as an ointment in the United States. Adverse reactions, such as allergy, toxic reactions, and resistance, are uncommon. It is beneficial in treating staphylococcal blepharitis when used at bedtime for 2 weeks in combination with lid hygiene (i.e., lid scrubs before applying the ointment). In addition, Polysporin, in combination with another antibiotic drop during the day, could be used in hyperacute bacterial infections and bacterial keratitis.
Bacitracin, Polymyxin B, and Neomycin
The combination of bacitracin (or gramicidin), polymyxin B, and neomycin is marketed generically and under the name of Neosporin (Monarch Pharmaceuticals). Neomycin, an aminoglycoside, is a broad-spectrum antibiotic that inhibits protein synthesis. Neomycin is not effective against Pseudomonas, which is why the polymyxin B is included. Neomycin is prone to hypersensitivity reactions, which can occur within 5 to 10 days or 12 to 72 hours, depending on whether the patient has been previously sensitized. When a reaction occurs, the symptoms can consist of injection of the lids and conjunctiva, mild edema of the eyelids, and superficial punctate keratitis (SPK). The reaction is treated simply by discontinuing the drug. Neosporin is available in solution and ointment forms. Neosporin is rarely used as an ophthalmic drug because of the potential for a hypersensitivity reaction.
Trimethoprim with Polymyxin B
Trimethoprim with polymyxin B is marketed generically and as Polytrim (Allergan). Trimethoprim is bacteriostatic by interfering with folic acid production. It is active against common gram-positive and gram-negative organisms with the exception of Pseudomonas, which is why it is combined with polymyxin B. It is available as a solution and is effective for bacterial conjunctivitis, as adverse effects are rare. When treating a bacterial conjunctivitis, it is recommended that one drop be instilled every 2 hours for 2 days, then four times a day (q.i.d.) for 5 more days.
Chloramphenicol
Chloramphenicol is marketed generically by various manufacturers as a solution (0.5%) or as an ointment (1%). Its mechanism of action is bacteriostatic by inhibiting protein synthesis. It is broad spectrum in activity, but it is not effective against Pseudomonas. Although it is used in Europe and Australia, it is minimally used in the United States because of reports of aplastic anemia as an adverse effect. Even topical doses, in some individuals, might result in bone marrow aplasia, making it a legal liability to use when there are other alternatives.1
Erythromycin
Erythromycin is bacteriostatic by inhibiting bacterial protein synthesis. It is only available topically in ointment form (0.5%) and is available from various generic manufacturers. It is effective against many gram-positive and some gram-negative organisms; however, staphylococcal bacteria may develop resistance over a few days. This prohibits its use in long-term treatment; however, it is an effective drug for prophylactic use in the management of corneal abrasion or other forms of corneal compromise. It provides gentle lubrication and antibacterial cover for compromised epithelial tissues.
Azithromycin
Azithromycin is available as a 1% ophthalmic solution with the name AzaSite, manufactured by InSite Vision and licensed to Inspire Pharmaceuticals, Inc. Orally, azithromycin is known as Zithromax, which comes as Z-Pak, Tri-Pak, and Zmax, an extended-release, 2,000-mg oral suspension. Azithromycin is a macrolide, like erythromycin, and inhibits bacterial protein synthesis. Patients who have experienced an allergy to erythromycin should avoid using azithromycin. The benefits of this drug ophthalmically are yet to be determined via widespread clinical use, but initially it may be useful for bacterial conjunctivitis in pediatric patients and mild to moderate cases of bacterial conjunctivitis in adults.
Gentamicin and Tobramycin
Gentamicin and tobramycin are aminoglycosides that are bactericidal by inhibiting protein synthesis. They are effective against gram-negative and gram-positive organisms, although they are most effective against gram-negative organisms, including Pseudomonas. Both are available in solution (0.3%) and ointment (0.3%) forms by various manufacturers, including Genoptic (Allergan) and Tobrex (Alcon), and generic forms. Gentamicin and tobramycin are very effective drugs and carry a very minimal risk of toxicity or allergic reaction. The symptoms of this reaction would be similar to neomycin with conjunctival injection, edema of the lid, and SPK. Typically, any reaction occurs after use longer than 1 to 2 weeks. Both gentamicin and tobramycin are effective choices to treat bacterial infections when treatment is going to be brief and, because of the available generic forms, reduced patient cost is important. A typical treatment regimen for these antibiotics would be to use one drop q.i.d. for 7 days.
Fluoroquinolones
Since the introduction of fluoroquinolones, the effectiveness of these pharmaceuticals has led to a near dominance of use by practitioners for bacterial infections, especially when the cornea is involved. Ocular fluoroquinolones are Ciloxan (0.3% Alcon and generic), Ocuflox (0.3% Allergan and generic), Quixin (0.5% Vistakon Pharmaceuticals), Vigamox (0.5% Alcon), Zymar (0.3% Allergan), and Iquix (1.5% Vistakon Pharmaceuticals). There could be a debate pertaining to the overuse of fluoroquinolones, when other antibiotics like Polytrim and tobramycin might be equally effective. A fluoroquinolone is useful to provide rapid treatment with minimal risk of toxicity. Fluoroquinolones work by inhibiting DNA synthesis.2 They are less toxic and more effective against gram-positive bacteria than aminoglycosides. Vigamox and Zymar perform more effectively against some gram-positive bacteria than the other fluoroquinolones. Vigamox is preservative free compared to Zymar, which is benzalkonium chloride (BAK) preserved and, along with enhanced penetration, results in often being the preferred drug.3,4 The fluoroquinolones are all available in solution form, and Ciloxan is also available in an ointment. Use of fluoroquinolones is usually reserved for moderate to severe infections. Table 21.1 provides the dosing frequency. Antibiotics should never be tapered to less than four times a day, as this could result in resistance.
TABLE 21.1 DOSING FREQUENCY FOR FLUOROQUINOLONES | ||||
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TABLE 21.2 TOPICAL ANTIBIOTICS AND ANTIBIOTIC/STEROID COMBINATIONS | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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Combination Antibiotic/Steroid Preparations
Common aminoglycoside-steroid combination drugs include Zylet (tobramycin and loteprednol) and TobraDex (tobramycin and dexamethasone). These combination drugs can be useful when there is a bacterial infection or epithelial disruption combined with inflammation, such as rosacea, vascularized limbal keratitis (VLK), contact lens-induced acute red eye (CLARE), phlyctenular keratoconjunctivitis, noninfectious keratitis, herpes zoster with ocular involvement, and staphylococcal blepharitis.5 These drugs should never be tapered below q.i.d. as this creates subtherapeutic levels of the antibiotic, which may cause antibiotic resistance. The section in this chapter pertaining to corticosteroids should be reviewed for a more complete understanding of this class of drugs. Table 21.2 provides a summary of the antibiotics covered in this section. Ocular conditions and the recommended antibiotic therapy are provided in Table 21.3.
▪ ALLERGY MEDICATIONS
The incidence of allergies is on the rise; therefore, practitioners must be prepared to effectively treat ocular allergies.6 Unfortunately, patients sometimes resort to over-the-counter drops that
“get the red out” without seeing an eye doctor. The symptoms of ocular allergy (redness and itching) should be evaluated to make sure that other forms of ocular disease, such as dry eyes or solution sensitivity, are not the cause. Patients manifesting dry eyes may experience itching and burning; therefore, tear film dysfunction should be ruled out initially. If patients are using a preserved contact lens care regimen, changing them to a nonpreserved system (i.e., hydrogen peroxide) to determine if that eliminates the symptoms should be attempted. Other helpful tips would include removing the offending source, frequent hand washing, use of cold compresses, refrigerating drops, and discouraging eye rubbing, which causes degranulation of mast cells, thus continuing the allergic cycle. Hair washing at night, before sleeping, has been found to help prevent irritants (pollutants, dirt, etc.) from being released onto the pillow, decreasing ocular allergies.6
“get the red out” without seeing an eye doctor. The symptoms of ocular allergy (redness and itching) should be evaluated to make sure that other forms of ocular disease, such as dry eyes or solution sensitivity, are not the cause. Patients manifesting dry eyes may experience itching and burning; therefore, tear film dysfunction should be ruled out initially. If patients are using a preserved contact lens care regimen, changing them to a nonpreserved system (i.e., hydrogen peroxide) to determine if that eliminates the symptoms should be attempted. Other helpful tips would include removing the offending source, frequent hand washing, use of cold compresses, refrigerating drops, and discouraging eye rubbing, which causes degranulation of mast cells, thus continuing the allergic cycle. Hair washing at night, before sleeping, has been found to help prevent irritants (pollutants, dirt, etc.) from being released onto the pillow, decreasing ocular allergies.6
TABLE 21.3 OCULAR CONDITIONS AND RECOMMENDED TREATMENT | ||||||||||||||
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If allergic conjunctivitis is the diagnosis, then antihistamine/mast cell stabilizers may be prescribed. There are four antihistamine/mast cell stabilizers: Elestat (Allergan), Optivar (MedPointe), and Patanol and Pataday (Alcon). Ketotifen 0.025% is available over the counter as Zaditor (Novartis), Alaway (Bausch & Lomb), and Refresh (Allergan). With the exception of Pataday, which is once-a-day (q.d.) dosage, the other medications are used twice a day (b.i.d.), morning and night. With the medications used twice a day, after the first 2 weeks, many patients can decrease to a maintenance dose of once a day.
Emadine (Alcon) is an antihistamine drop that can be used for ocular allergy; however, it may be more useful for lid myokymia (lid twitch). The dosage for this is q.i.d. for 2 weeks followed by b.i.d. for 1 to 2 weeks.
For patients experiencing ocular allergy with clinical inflammation, a topical steroid such as Alrex (Bausch & Lomb) or FML (Allergan) used every 2 hours for 2 days, then every 4 hours for a week, then once or twice a day for several more days to weeks, is beneficial. If the inflammation is more severe, Lotemax (Bausch & Lomb) can be used.
Mast cell stabilizers such as Alamast (Vistakon) and Alocril (Allergan) are best used as a maintenance drug than a treatment for acute allergy. First-generation mast cell stabilizers like Crolom, Opticrom, and Alomide have become relatively obsolete since the new formulations became available. When patients are aware of the trigger to their ocular allergy and realize that they will be exposed to the trigger, such as exposure to cats, use of a mast cell stabilizer used q.i.d. 1 week in advance can minimize or eliminate the allergic reaction. Mast cell stabilizers are safe to use for long periods of time, weeks to months. The various topical allergy drops are listed in Table 21.4.
For contact lens wearers, antihistamine/mast cell stabilizers can be used a few minutes before insertion and again after contact lens removal. If necessary, the drop can be instilled on top of the contact lens; however, preservative incompatibility may be an issue. For those contact lens wearers who experience seasonal ocular allergies, use of Lotemax with an antihistamine/mast cell stabilizer morning and evening, before and after contact lens wear, then decreasing the Lotemax to evening use only, will aid the patient in surviving the allergy season.
TABLE 21.4 TOPICAL ALLERGY DROPS | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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Giant papillary conjunctivitis (GPC) is discussed in Chapter 13. Discontinuing contact lenses is warranted in severe cases; however, using nonpreserved solutions, new contact lenses (daily disposable contact lenses are very beneficial), and an antihistamine/mast cell stabilizer once or twice a day will benefit most patients. In very severe cases, where lenses are not discontinued, prescribing steroid use until the patient is stabilized and the tarsal conjunctiva has returned to a more normal looking appearance, followed by prescribing an antihistamine/mast cell stabilizer or mast cell stabilizer while tapering the steroid, is helpful.
Contact dermatitis may be caused by an environmental irritant or an allergic response. In either case, removal of the irritant, cold compresses, a topical steroid cream (such as 0.1% triamcinolone) applied around the lids (but not in the eye), and/or a systemic antihistamine will provide relief. In most cases, removing the irritant and use of cold compresses will be therapy enough. Severe cases may require the addition of the steroid cream (i.e., 0.1% triamcinolone) and/or the oral antihistamine (i.e., Benadryl). The allergic response with the recommended medications is provided in Table 21.5.
▪ CORTICOSTEROIDS
General Information
The inflammatory process is the result of infectious, allergic, or traumatic factors, which cause the tissue to release prostaglandins as mediators of the response. Adverse effects of the inflammatory response may be mitigated by use of pharmaceutical agents, such as corticosteroids.
To better understand how anti-inflammatory agents are effective, it is useful to understand what occurs during the inflammatory process. When infections, allergy, or trauma affect the tissue, phospholipids are released from the cell membrane. These phospholipids convert to arachidonic acid. Arachidonic acid is converted to prostaglandins or leukotrienes via one of two enzymes, either cyclooxygenase or lipoxygenase. Corticosteroids inhibit phospholipid conversion to arachidonic acid; thus, corticosteroids work early in the inflammatory process. Nonsteroidal anti-inflammatory drugs (NSAIDs; which will be discussed in the next section) exhibit their effect further in the pathway to inhibit cyclooxygenase, which converts arachidonic acid to prostaglandins. NSAIDs do not affect the production of leukotrienes; thus, this limits their use in treating inflammatory processes.2,7,8
To better understand how anti-inflammatory agents are effective, it is useful to understand what occurs during the inflammatory process. When infections, allergy, or trauma affect the tissue, phospholipids are released from the cell membrane. These phospholipids convert to arachidonic acid. Arachidonic acid is converted to prostaglandins or leukotrienes via one of two enzymes, either cyclooxygenase or lipoxygenase. Corticosteroids inhibit phospholipid conversion to arachidonic acid; thus, corticosteroids work early in the inflammatory process. Nonsteroidal anti-inflammatory drugs (NSAIDs; which will be discussed in the next section) exhibit their effect further in the pathway to inhibit cyclooxygenase, which converts arachidonic acid to prostaglandins. NSAIDs do not affect the production of leukotrienes; thus, this limits their use in treating inflammatory processes.2,7,8
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