Manage Anterior Segment Disorders
Use contact lenses to manage these six anterior segment disorders.
GREGORY W. DENAEYER, O.D., Columbus, Ohio.
ILLUSTRATION BY ERIC LINDLEY
Although many of us think of contact lenses solely as refractive correction devices, several eyecare practitioners, including myself, have expanded the contact lens portion of their practice by using these medical devices therapeutically.
The result: an increased level of patient care, which has further bound patients to their practice and created patient referrals.
Here, I discuss the general principles of contact lenses as therapeutic devices and their application to treat six anterior segment disorders, so you too can provide this greatly appreciated service.
Therapeutic soft lenses
Soft lenses have the potential to serve three main functions with respect to managing anterior segment disorders:
1. They act as a physical barrier between a compromised cornea and the lids, which is important because the mechanical friction from blinking delays healing.
2. They manage pain caused by outside exposure.
3. They provide a temporary seal for a perforated wound.
Soft bandage lenses have virtually replaced pressure patching because of their ease of application, cosmetic and functional appeal to the patient and the patient's ability to continually apply topical ophthalmic medications, such as antibiotics.
When choosing a soft lens for medical use, consider these factors:
• Lens material. I've discovered that for most patients, silicone hydrogel lenses are the best option. This is because their high Dk/t values allow for safe use on an extended-wear basis, and re-epithelialization is fast.
2. Lens modulus (lens stiffness). A high modulus, or stiff lens, may help mask minor amounts of irregular astigmatism, which will improve vision for a patient who is wearing the lens for both sight and treatment. A low modulus, or less stiff lens, may fit best on a highly irregular cornea because it's able to more easily drape the unevenness or irregularity of the cornea.
3. Water content. You should weigh this factor for cases in which anterior segment hydration is an issue. For example, a high-water content soft lens may help to draw fluid out of a swollen cornea, wicking water away to rehydrate itself (meaning the lens). Meanwhile, a low water-content lens may be helpful to patients who have ocular surface disease related to dryness because it draws less water away and protects the compromised cornea like a bandage.
Once you choose a lens, the next step is to fit the lens properly. Less lens movement is best, especially when you're using the lens for healing corneal defects. (A lens with lot of movement will delay healing secondary to mechanical irritation of the epithelium.) Because most patients who have corneal defects will wear therapeutic soft lenses on an extended-wear (overnight) basis, however, be sure to preclude corneal adherence. If a lens becomes stuck to the cornea, the patient will be prone to keratitis.
To prevent this, evaluate the fit of the steeper of the base curve radii of your lens of choice. If the lens doesn't move upon blink and you're unable to manually move the lens off center using the patient's lid, default to the flatter base curve, or switch lens brands.
Also, educate the patient that frequent follow-up visits of one-to-three days are necessary, so you can monitor him for any complications, such as lens adherence and keratitis. (See "Silicone Hydrogel Lenses Approved For Therapeutic Use," below.)
|Silicone Hydrogel Lenses Approved For Therapeutic Use|
1. Acuvue Oasys with Hydraclear Plus (senofilcon a) (Vistakon). As of the summer of 2007, the Food and Drug Administration (FDA) approved this lens for therapeutic use (daily or extended-wear) for the following acute and chronic conditions:
2. PureVision (balaficlon A) (Bausch & Lomb). As of Spring 2005, the FDA approved this lens for therapeutic use as a bandage contact lens for:
3. Night & Day (CibaVision). As of Spring 2003, the FDA approved this lens for therapeutic use (30 continuous nights) as a bandage in protecting the cornea and relieving corneal pain in the treatment of:
Therapeutic RGP Lenses
Scleral lenses comprise the therapeutic RGP modality. Practitioners don't use mini-scleral RGP lenses for therapeutic use because they usually have diameters between 15mm to 16mm — limiting their ability to hold the tear reservoir at a level needed for most therapeutic purposes.
Modern-day RGP materials and the use of trial lens fitting sets have revolutionized scleral lenses — dramatically increasing their popularity for fitting compromised and irregular corneas.
Scleral lenses generally have an 18mm or greater diameter. A diameter of this size allows them to vault the cornea and form a semi-seal to the eye. This arrangement allows them to hold a liquid reservoir, which for therapeutic purposes, I've found is ideally between 100 microns to 300 microns.
This liquid reservoir isn't only able to mask irregular astigmatism, but also acts as a liquid bandage for the cornea (see figure 1).
Figure 1: This 18.2mm scleral RGP contact lens provides a liquid reservoir to act as a liquid bandage for the cornea.
Practitioners reserve scleral lenses for patients who have extreme corneal compromise, especially those who've already tried a soft therapeutic lens without success (see below).
Because practitioners have scleral lenses custom made for the patient, the fitting process requires more time than that of most soft lens fittings. You shouldn't fit these lenses empirically because this is not a good way to predict the final lens parameters without diagnostic lens fitting. Therefore, a fitting set is imperative.
The ideal fit: When the lens rests on the scleral conjunctiva and vaults the corneal surface, including the limbus, as it minimizes or eliminates lens bearing on the compromised cornea.
To obtain this vault, the lens must have a greater sagittal depth than the anterior surface that it covers. This fit is unlike conventional RGPs, in which you determine the fit by the base curve-to-keratometry relationship because the corneal RGP closely contours the cornea. Since the lens is semi-sealed, you should see no movement. Tear exchange for the reservoir occurs through lens flexure.
If you're an inexperienced scleral lens fitter, it's critical you discuss the patient's needs with the lens manufacturer to ensure you provide the patient with the most appropriate lens. With the best lens in place, you can perform an over refraction to determine the power. Order the lens in a high Dk/t material to prevent corneal hypoxia. Also, a plasma treatment is essential to ensure surface wetting of the lens.
Now, I'll explain how you can use either soft or RGP therapeutic lenses to manage these six anterior segment disorders.
1. Persistent epithelial defects (PED)
PEDs are serious sight- and eye-threatening complications because the epithelial layer is a protective barrier from the outside environment, including all pathogens. PEDs result secondary to numerous conditions, such as neurotrophic keratitis and corneal stem cell deficiencies that cause anterior surface compromise.
For these patients, select an extended wear (overnight) soft lens to be worn until the defect heals. This type of lens helps decrease pain secondary to wound exposure and also aids in healing by protecting the compromised epithelium from the friction of the lids.
Also, prescribe a fluoroquinolone antibiotic q.i.d. until the PED is healed to protect the cornea from all bacterial infections.
Something else to keep in mind: The medical literature suggests that autologous serum drops in combination with a soft lens can be helpful for PED patients.1 This is because autologous serum, which is made from the clear part of a patient's blood, contains the essential tear components: epidermal growth factor (EGF), vitamin A, transforming growth factor, fibronectin and various other cytokines, which work to maintain corneal health.2
Now, schedule the patient for frequent follow-up visits to monitor the fit of the lens and to check on healing progression. The patient's progress will determine the frequency of visits.
If the lens doesn't stay in place, employ a scleral RGP lens instead, which will provide a combination of moisture and protection of the fragile epithelium.3
Practitioners often comanage the PED patient with a corneal specialist, as penetrating keratoplasty (PKP), tarsorrhaphy (the suturing of the upper and lower eyelids together to shorten or close the palpebral fissure) or amniotic membrane transplantation (suturing an overlay of amniotic membrane over the anterior segment to promote epithelial healing) are alternative treatments if the scleral lens fails. (See figure 2.)
Figure 2: Tarsorrhaphy is an alternative treatment if the scleral lens fails to provide relief for the persistent epithelial defect patient.
2. Stevens-Johnson syndrome
Stevens-Johnson Syndrome is a rare systemic condition that causes bullous eruptions of the skin and mucous membranes. It often occurs secondary to an allergic reaction to drugs, such as ibuprofen, anti-convulsants, antibiotics, anti-inflammatory medication, or viral infections, such as herpes simplex virus.4,5 Ocular involvement occurs in 50% of patients, and its manifestations include keratopathy, symblepharon and entropia.6 These ocular changes can be permanent after the acute phase of the reaction.
Fit these patients in a scleral RGP lens, as the liquid reservoir provided by the lens is therapeutic for these extremely compromised corneas.7 Prescribe the lenses for daily wear indefinitely, and the patient should use artificial tear gel or ointment prior to bedtime to quell symptoms of irritation when not wearing the lens.
Typical follow-up for these patients is every three to six months, so you can monitor the contact lens fit and health of the anterior surface.
Some practitioners comanage these patients with corneal specialists, as amniotic membrane transplantation is an alternative treatment, should the lens fail.
3. Corneal erosions
Corneal erosions are spontaneous, painful abrasions that occur due to an abnormal basement membrane secondary to corneal dystrophy or previous corneal trauma. (See figure 3.)
Figure 3: A patient with corneal map-dot-fingerprint dystrophy.
Fit these patients in a silicone hydrogel bandage lens with minimal movement on an extended-wear basis (overnight) until the erosion resolves. A soft bandage lens is perfect for these cases because it functions by minimizing pain secondary to wound exposure and helps protect the healing epithelial cells from the blinking lid.
Also, prescribe a fluoroquinolone antiobiotic q.i.d. for prophylaxis against all types of bacteria until the corneal erosion is 100% healed.
Schedule the patient for follow-up visits every one to two days to monitor resolution and lens complications, such as lens adherence and keratitis.
Once the abrasion is healed, remove the lens. To prevent the induction of erosion upon removal, lubricate the eye first with an artificial teardrop, and remove the lens from the sclera.
To preclude a recurrent corneal erosion, prescribe hypertonic ointment for use prior to bedtime for the typical duration of three months to aid in the lubrication between the lids and the cornea and to decrease swelling.
Some practitioners comanage these patients with corneal specialists, as anterior stromal puncture and PKP may become necessary, should the soft lens and hypertonic ointment fail.
4. Band keratopathy
Band keratopathy is a calcium plaque that builds in the anterior corneal surface located in the palpebral fissure zone. (See figure 4.) It usually has a Swiss cheese appearance and often results secondary to chronic uveitis, severe glaucoma or ocular trauma.
Figure 4: Notice the calcium plaque in this patient who has band keratopathy.
For mild cases (i.e. minimal symptoms of irritation), prescribe artificial tears, which act to quell symptoms of irritation caused from the rough corneal surface secondary to the plaque.
If artificial tears aren't sufficient, prescribe a soft lens, which acts as a barrier between the irregular calcific epithelium and lids. You can order these lenses in a tint or color for cosmetic purposes. Of note: Currently, you cannot paint silicone hydrogel lenses. (See figure 5.)
Figure 5: Eye from figure 3 with a prosthetic therapeutic soft contact lens.
The typical follow-up for these patients is every six months so that you can monitor lens fit and the health of their corneal surface.
Some practitioners comanage these patients with a corneal specialist when the soft lens is unsuccessful and the surgeon is needed to attempt to remove the calcium plaque by chelation using ethylene-diamine-tetra-acetic acid (EDTA).
5. Graft vs. host disease (GVHD)
GVHD is a consequence of donor immune cells attacking the recipient following allogeneic bone marrow or cord blood transplantation. Researchers have reported that 40% to 60% of these patients will suffer from ocular involvement resulting in severe keratoconjunctivitis sicca.8
Initially, treat these patients with non-preserved artificial tears, which act to keep the eye lubricated. Prescribe the tears for use four to eight times a day indefinitely, for every couple of hours. Research has shown that 0.05% topical cyclosporine (Restasis, Allergan) and autologous serum are both clinically effective in treating these patients.9,10
Patients who don't achieve relief via artificial tears, may still require a therapeutic lens for protection from exposure. Start by fitting these patients in a silicone hydrogel soft lens on a daily wear basis indefinitely, as the lens acts like a bandage lens to cover the dried ocular surface.
If the patient is already using cyclosporine or autologous medications, have him continue using these medications on a b.i.d. dosing schedule indefinitely before and after lens removal, so the patient can receive the therapeutic benefit of both the soft lens and the ophthalmic medication.
Now, prescribe preservative-free artificial tears to use over the contact lens for instillation during the day in addition to the cyclosporine and autologous medications, and artificial gel or ointment for installation prior to bedtime to keep the patient's dry eyes lubricated.
Ocular GVHD patients who have more severe symptoms may benefit from wearing the soft lens on an extended-wear basis (overnight) indefinitely to obtain 24-hour protection.11 You may prescribe autologous serum and artificial tears in conjunction with the patient's extended-wear soft lens so the patient has the added benefit of multiple therapies.
If the patient doesn't achieve significant relief with the extended-wear soft lens, fit him in a scleral RGP lens to be worn on a daily wear basis, as the liquid reservoir will continually keep the eye lubricated.8,12 Also, consider prescribing the indefinite use of autologous serum and/or cyclosporine b.i.d. before and after lens removal.
The typical follow-up for these patients is every three to six months, so you can reevaluate the contact lens fit and corneal health.
6. Bullous keratopathy
Bullous keratopathy are blister-like lesions of the anterior corneal surface. They result from edema caused by decreased endothelial function secondary to Fuch's corneal dystrophy or endothelial damage from intraocular surgery.
You should initially treat these patients with hypertonic solutions to reduce edema q.i.d. until resolution. If the bullae rupture, which produce painful epithelial defects, fit the patient in an extended-wear (over-night) soft lens until resolution. Start with a high-water content lens that is able to help draw fluid out of the cornea. Drawing fluid out of the cornea reduces the edema. Prescribe a fluoroquinolone antibiotic q.i.d. for prophylaxis against all types of bacteria until resolution.
Monitor these patients every one to three days to check for progress and signs of complications, such as lens adherence and keratitis.
Some practitioners comanage these patients with a corneal specialist, as corneas unresponsive to treatment require keratoplasty.
As illustrated above, soft and RGP lenses are invaluable medical management tools that provide an increased and greatly appreciated level of patient care.
I've discovered that I can treat most anterior segment disorders with the lenses I've already stocked in my office for vision correction purposes.
For extreme corneal compromise, especially when a soft therapeutic lens hasn't adequately improved the patient's condition, I employ a scleral RGP. Modern fitting processes of scleral lenses allow any clinician with a trial lens set and training to utilize this therapeutic modality. OM
1. Schrader S, Wedel T, Moll R, Geerling G. Combination of serum eye drops with hydrogel bandage contact lenses in the treatment of persistent epithelial defects. Graefes Arch Clin Exp Ophthalmol. 2006 Oct;244(10):1345-9.
2. Tsubota K, Goto E, Shimmura S, Shimazaki J. et al. Treatment of persistent corneal epithelial defect by autologous serum application. Ophthalmology. 1999 Oct;106 (10):1984-9.
3. Rosenthal P, Cotter JM, Baum J. Treatment of persistent corneal epithelial defect with extended wear of a fluid-ventilated gas permeable contact lens. Am J Ophthalmol. 2000 Jul;130(1):33-41.
4. Steven Johnson Syndrome Foundation. The Official Site. The Facts About Stevens-Johnson Syndrome (SJS) www.sjsupport.org/pdf/SJS_factsheet.pdf. Accessed July 9, 2008.
5. Choy AC, Yarnold PR, Brown JE, et al. Virus induced erythema multiforme and Stevens-Johnson syndrome. Allergy Proc. 1995 Jul-Aug;16(4):157-61.
6. Catania L. Systemic Considerations in Anterior Segment Care: Diagnostic Entities by Medical Specialties and Classifications. In: Primary Care of the Anterior Segment. 2nd ed. Stamford, Connecticut: Appleton & Lange; 1995: 400
7. Romero-Rangel T, Stavrou P, Cotter J, et al. Gas-permeable scleral contact lens therapy in ocular surface disease. Am J Ophthalmol. 2000 Jul;130(1):25-32.
8. Takahide K, Parker PM, Wu M, et al. Use of fluid-ventilated, gas-permeable scleral lens for management of severe keratoconjunctivitis sicca secondary to chronic graft-versus-host disease. Biol Blood Marrow Transplant. 2007 Sep;13(9):1016-21.
9. Wang Y, Ogawa Y, Dogru M, et al. Ocular surface and tear functions after topical cyclosporine treatment in dry eye patients with chronic graft-versus-host disease. Bone Marrow Transplant. 2008 Feb;41(3):293-302.
10. Ogawa Y, Okamoto S, Mori T, et al. Autologous serum eye drops for the treatment of severe dry eye in patients with chronic graft-versus-host disease. Bone Marrow Transplant. 2003 Apr;31(7):579-83.
11. Russo PA, Bouchard CS, Galasso JM. Extended-wear silicone hydrogel soft contact lenses in the management of moderate to severe dry eye signs and symptoms secondary to graft-versus-host disease. Eye Contact Lens. 2007 May;33(3):144-7.
12. Jacobs DS, Rosenthal P. Boston scleral lens prosthetic device for treatment of severe dry eye in chronic graft-versus-host disease. Cornea. 2007 Dec;26(10):1195-9.
|Dr. DeNaeyer is the clinical director for Arena Eye Surgeons in Columbus, Ohio. His primary interests include specialty contact lenses and anterior segment disease. E-mail him at firstname.lastname@example.org.|