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23rd Annual Contact Lens Report Bandage lenses help us manage many pathological conditions, but are not without risk. Here's how to use this form
of therapy most effectively. by Robert A. Ryan, O.D., Rochester, N.Y. The use of contact lenses for therapeusis is not a novel idea. In ancient Rome, physician Aulus Celsus used honey-soaked linen as an ophthalmic dressing to
treat ocular disease.1 By the mid-1900s doctors used PMMA scleral shells to manage ocular pathology.2 Researchers have been exploring indications and modalities using hydrogel lenses to treat ocular surface disease since the
late 1960s.3 More recent work has shown disposable lenses to be a safe, efficacious and cost-effective alternative to traditional bandage lenses, although the FDA has not approved them for this purpose.4 Even with technological
and material advances over time, the use of bandage lenses remains somewhat controversial. When used judiciously, they can be an effective way to manage many pathological conditions and provide relief to the patient, although there
is risk of complications. In this article, we'll discuss when you should consider a bandage lens, how to use it most effectively and how to avoid complications. Applications Studies have shown that HBLs, compared
with pressure patching, expedite the rate of epithelial repair and greatly enhance comfort.5 Specifically, an HBL: • Provides the traumatized cornea with a mechanical barrier against the shearing forces of the lids.
• Amplifies drug delivery to the anterior segment.6 • Possibly heightens lubrication therapy, since the lens acts as a reservoir for continuous sustained hydration.7 • Provides a splinting effect. You may temporarily treat a
corneal laceration by using a thick/stiff bandage lens. Also, you can often manage a wound leak or perforation in this fashion, allowing the anterior chamber to reform and restoring near normal intraocular tension. This delays the
urgency and, in some cases, eliminates the need for surgical intervention. Rigid gas permeable lenses have long been used as a definitive treatment for non-inflammatory thinning disorders, such as keratoconus and keratoglobus.
However, specialty soft lenses may offer improved acuity in cases of more subtle surface irregularity. Also, they can discourage erosions in patients who have poor epithelial adherence.
Here are some specific clinical applications for bandage lenses in your practice. Keratitis Sicca Here's what you need to do when patients present with dry eye complaints: • Examine the
ocular surface and adnexa. Patients may not always articulate their symptoms accurately, so you'll need to confirm the diagnosis. • Determine the cause. Is the patient's condition due to a tear deficiency or an evaporative
problem? Consider tear-volume testing such as Schirmer's and phenol red thread. Also perform biomicro-scopy of the precorneal tear film for stability and volume. Disclosure dyes such as fluorescein, rose Bengal and Lissamine green
enhance evaluation by revealing tear breakup time, devitalized cells, mucin deficiency and surface insult. Carefully study eyelid margins and glands for maladies that contribute to evaporative problems. Blepharitis and meibomian
inspissation directly correlate to a compromised lipid layer, resulting in ac- celerated aqueous layer evaporation. Malfunctioning lids, as seen in ectropion, lagophthalmos, seventh nerve palsy and trauma predispose individuals to
exposure and/or neuroparalytic keratopathy. • Try all other conventional measures. Clearly, you should try the frequent use of artificial tears before you suggest bandage lens therapy. Unfortunately, many patients are too busy,
spend most of their day working at a computer or feel limited subjective relief from presently available eye drops. Punctal occlusion may be another option where appropriate. We suggest punctal occlusion more for tear-deficient
etiologies of keratitis sicca than evaporative ones. • Choose an appropriate lens material. If you eventually resort to bandage lens therapy, the cause of the patient's condition should dictate which lens you choose. Consider
high-water (group 2 or 4) mate- rials for patients with tear deficiency. These deliver additional moisture to the corneal surface. The patient probably will still need to use tear supplements, but the HBL will allow water to
collect within the lens matrix and ultimately be released to the eye.
One precaution when using bandage lens therapy to treat dry eye: We must remember that a compromised precorneal tear film may predispose individuals to infectious keratitis. Therefore, prophylactic topical antibiotic therapy may be prudent. Epithelial Disorders
Two specific applications: Repair mechanisms of the corneal epithelium occur rapidly. Epithelial migration via chemotaxis and growth factors encourages closure of most defects within 24-48 hours. Cellular attachments called hemidesmosomes anchor the basal epithelium to the underlying Bowman's membrane and anterior stroma. In patients with basement membrane dystrophy or diabetes, these bonds may be
especially susceptible to disruption. A full eight weeks of continuous HBL therapy is indicated to restore these attachments.11 Should the defect recur during this time, an
additional eight-week period is indicated. I typically employ a group-4 extended-wear material (i.e. etafilcon) on a full-time wear schedule with weekly replacement. More conventional means of treating erosions, specifically, hyperosmotic agents and pressure patching are not as well-tolerated and are contraindicated in contact lens-related defects. Surgical alternatives, including stromal micro-puncture, epithelial debridement and excimer laser phototherapeutic keratectomy (PTK) have been reported to be effective for managing patients whose conditions don't resolve completely with bandage lens therapy. • Surface irregularity. An irregular epithelial surface can result in light scatter, leading to significant visual disturbance. Etiologies for surface irregularity include epithelial basement membrane dystrophy, Meesman dystrophy, Reis-Buckler's and other anterior stromal corneal dystrophies, Thygeson's superficial punctate keratitis and superficial corneal leukoma. Symptoms are photophobia, epiphora, pain, and difficulty with glare and blurred vision. A thick lens or non-HEMA material may mask the irregularity, reduce discomfort and improve acuity. Again, surgery may ultimately be indicated depending upon functional limitations. Options include excimer PTK, epithelial debridement, or lamellar or penetrating keratoplasty. Bullous Keratopathy Several conditions may contribute to the development of corneal bullae. Among them: corneal guttata, Fuchs' endothelial dystrophy, uncontrolled glaucoma, surgical trauma and intraocular lens implants. Endothelial compromise is the common denominator. Remember, the endothelium is a single layer of hexagonal-shaped cells joined by tight junctions. These cells cannot carry out mitosis but act as a barrier to prevent aqueous from entering the posterior stroma. They also provide an active transport pump mechanism to maintain corneal deturgescence. Physiological breakdown of this layer results in stromal edema, which contributes to bullous keratopathy. Symptoms include reduced acuity, glare, photophobia, blepharospasm and intense pain upon rupture of the bullae. Your treatment goal is to alleviate stromal and epithelial edema. In milder cases, desiccation therapy with hyperosmotic agents may provide some improvement. If IOP is elevated, you may need to treat the pressure pharmacologically before initiating more sophisticated measures, such as bandage lens therapy or surgical alternatives. Bandage lens therapy can be extremely effective in these cases, offering multifaceted relief. Thick, high-water content lenses are suggested for their ability to "wick" moisture from the cornea and allow it to evaporate. HBLs also provide a protective barrier to tamponade the bullae and minimize lid interaction. At the same time, they mask irregularity and improve acuity. However, watch for lens-induced hypoxia with a commensurate increase in edema and reduction in acuity.14 If a bandage lens fails to provide relief, you'll need to refer the patient for penetrating keratoplasty, which is highly successful, and for treatment of the underlying etiology. For example, the surgeon might need to exchange the patient's IOL so the bullae don't recur in the corneal graft. A conjunctival flap may provide palliative treatment in situations of limited visual potential. Fortunately, as surgical techniques and IOL designs have evolved, bullous keratopathy presents less often. Historically, generous limbal incisions, intracapsular cataract extractions and iris clip or anterior chamber IOLs were not particularly kind to the fragile endothelium. Newer cataract surgery techniques that involve small, clear corneal wounds have hastened recovery. Also, posterior chamber IOLs have done very little to insult the endothelium. Complications • Corneal edema and hypoxia. A low-oxygen flux lens and, to a certain extent, tight-fitting lens may lead to poor tear exchange and hypoxia. This situation does not promote healing, adversely affecting corneal metabolism by changing from aerobic to anaerobic respiration. • Neovascularization. Hypoxia predisposes patients to neovascularization. This may ultimately dump potentially sight-threatening lipids into the corneal stroma. Vascularization is of particular concern following penetrating keratoplasty, because a more vital immune response may threaten graft success. • Papillary conjunctivitis. This is less of a concern now that disposable lenses are available in a wide array of parameters and materials. Remember, disposable lenses are not FDA-approved for bandage lens applications. • Sterile infiltrates. These, too, may occur, and you must differentiate them from infectious keratitis. A good rule of thumb: When in doubt, culture and treat initially with broad-spectrum antibiotics. Remember, yeast or other fungal infections are possible when using a bandage contact lens. Drug Delivery
Bactericidal concentrations of antibiotics have been recovered in the precorneal tear film for up to three days following application of HBLs soaked in the drug. Also, greater
anterior chamber concentrations have been measured in the presence of an HBL than by simple topical application without a lens in place.18 Apparently, the lens can absorb the
agent, prolong the contact time with the ocular surface and provide time-released action. • Avoid prescribing ointments. These can soil and coat the lens, resulting in poor comfort, blurred vision and decreased stability of the lens fitting relationship. • Don't alter the prescribed dosage simply because you're also using an HBL. The presence of an HBL does not alter the normal bacterial flora of the cornea or conjunctiva. 19,20 Nor is there any dif- ference observed in normal flora with or without the use of prophylactic antibiotics. • Alternate antimicrobial agents every four to five weeks. This will reduce the chance that the bacteria will develop a resistant strain. Also, exercise caution when using HBLs on a compromised eye. Many clinicians feel it is prudent to prescribe antibiotic prophylaxis, particularly when there's significant keratopathy. Biodegradable collagen shields are available for use as bandage lenses. These come in a dehydrated state, so you must reconstitute them, often with the appropriate topical medication, before you place them on the eye. The shields dissolve in 12-72 hours, depending upon the cross linking of the material and the patient's tear chemistry. Bandage lens therapy has become a very important tool in treating a variety of clinical problems, including keratitis sicca, epithelial disorders and bullous keratopathy. They can provide pain relief and allow for corneal re-epithelialization. Strictly maintain careful follow-up and appropriate adjunct therapies when using these lenses. Patients truly appreciate the rapid relief and freedom from pressure patching, and deserve access to the ultimate in quality of care.
Dr. Ryan is in group practice in Rochester, N.Y. 1. Arrington GE. A History of Ophthalmology. MD Publications: New York, 1959. |
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