HEALTHY LENS WEAR
Achieving Healthy Contact Lens Wear
Expert clinicians discuss new contact lens and lens care technologies that aim toward healthy lens wear.
By N. Rex Ghormley, OD, FAAO
In the last few years, we've seen many new contact lens materials and lens care products introduced into the market. By the end of this decade, the majority of contact lens products that practitioners recommended in the 1990s will be extinct. Most new products were developed to provide our patients with healthy lens wear.
I discussed the topic of "Achieving Healthy Contact Lens Wear" with three prominent clinicians: Carmen Castellano, OD, FAAO; Glenda Secor, OD, FAAO; and Jennifer Smythe, OD, FAAO. Dr. Castellano is in private practice in St. Louis, Missouri and is a past chair of the Contact Lens & Cornea Section of the American Optometric Association. Dr. Secor is in private practice in Huntington Beach, California and is the current chair of the Cornea & Contact Lens Section of the American Academy of Optometry. Dr. Smythe is an associate professor at the Pacific University College of Optometry and is the current chair of the Association of Contact Lens Educators. All three are Diplomates of the Cornea & Contact Lens Section of the American Academy of Optometry.
Silicone Hydrogel Lenses
Dr. Ghormley: Do you agree with the statement that silicone hydrogels are the future of soft contact lenses? Do you think silicone hydrogel lenses are healthier than hydrogel lenses? Have silicone hydrogels decreased lens complications in your practice?
Dr. Castellano: Yes, I believe silicone hydrogel lenses are the future of soft contact lenses, at least until the next significant breakthrough enters the marketplace.
We've made silicone hydrogel lenses the soft lens material of choice in our practice for both daily and overnight wear. I think for the most part that silicone hydrogel lenses do provide a healthier, safer and more comfortable mode of soft lens wear. We still occasionally see patients who can't keep the lenses clean and wet on the eye, which results in decreased comfort but this is the exception to the rule. Overall we see fewer complications and happier patients with these materials.
We've used several of the new silicone hydrogel toric lenses in our practice. Most patients fit with silicone hydrogel toric lenses have whiter eyes, and I expect to see a decrease in inferior vascularization.
Dr. Secor: Contact lens researchers certainly indicate that the future is in silicone hydrogel lenses. No major companies are currently performing research with HEMA lenses. Silicone hydrogels are much healthier because of their increased oxygen permeability. Chronic effects of hypoxia, such as peripheral neovascularization, may occur whether a patient reports redness or practitioners observe the problem. With silicone hydrogels I see reduced complications because of reduced chronic hypoxia, less red eyes, decreased dryness symptoms and fewer infiltrative events.
I've also used toric silicone hydrogels, and these patients report increased long-term comfort and fewer complications. Prism ballast designed lenses have a greater thickness differential; thus a lens with increased oxygen transmission should reduce inferior neovascularization.
Dr. Smythe: I strongly believe that silicone hydrogel lenses are the future of soft contact lens practice, and their tremendous growth in the marketplace supports this theory. These materials have virtually eliminated complications related to hypoxia. I no longer see limbal hyperemia, neovascularization, chronic microcysts or edema-related topography changes with these lenses.
The three new silicone hydrogel toric lenses have been a welcome addition to my contact lens practice. It's still early to report on long-term vascular responses because the designs are fairly new to the market. However, I predict that the reduction in hypoxic-related complications would be similar to that with spherical silicone hydrogel lenses. Inferior neovascularization and corneal topographical changes are fairly common in low-Dk, ballasted soft toric lenses in particular. These are definitely related to oxygen permeability, and we should see a reduction in these complications with high-Dk materials.
Dr. Ghormley: Do you recommend soft and GP continuous wear (CW) lenses in your practice? Is it important to use a hyper-Dk lens for CW? Who are good CW candidates? What's the major ocular complication that you see with your CW patients?
Dr. Castellano: We present the CW option to all patients whom we feel might be good candidates, including patients who have worn lenses on a CW schedule in the past, compliant and successful daily wear patients and new patients who have healthy eyes, a good tear system and no lid disease.
Generally for CW we recommend soft lenses that have a Dk/t of 120 or higher and hyper-Dk GPs. With this approach we've seen minimal complications. Occasionally we see infiltrative keratitis, but complications appear less severe with these materials.
Dr. Secor: I recommend CW up to 30 nights in my practice. But, I also educate my patients to remove their lenses frequently when situations require it, such as during an illness, after swimming or if they experience any problems with vision or comfort. It's mandatory that we all use hyper-Dk contact lenses for CW. They give us confidence that we have prescribed a contact lens that will provide enough oxygen to the majority of patients who have different oxygen requirements.
Good candidates for CW have clean, wet eyes, a history of contact lens compliance and an absence of ocular inflammatory events. I have seen minimal complications with my CW patients. If silicone hydrogel wearers experience an inflammatory event, they tend to respond quickly to proper treatment and can resume contact lens wear sooner than can low-Dk lens wearers. Superior epithelial arcuate lesions (SEALs) and giant papillary conjunctivitis (GPC) have been an occasional problem because of the stiffer modulus of some silicone hydrogel lenses. Refitting these patients into lower-modulus lenses can eliminate these complications.
Dr. Smythe: Many patients want the flexibility of CW, and we have to recognize that they often nap or sleep overnight in their lenses regardless of our recommendations. I prescribe CW, but only with high-Dk silicone hydrogel or hyper-Dk GP materials.
Not every patient is a CW candidate. Risk increases with certain traits such as smoking or sleeping in lenses after participating in water activities. Patients who have ocular surface disease, diabetes or compromised immune systems are poor candidates. I also don't recommend CW for older children or adolescents because of concerns with compliance. If they experience a problem or discomfort with lens wear, they may be less motivated to temporarily wear spectacles. Good candidates are compliant with follow-up care, in good health and able to understand the risks associated with overnight wear.
To reduce the risk of complications, I recommend to all CW patients: Replacement and removal on the planned schedule; daily wear during any period of illness; removal, cleaning and disinfecting lenses before overnight wear after water activities or anytime that the patient removes a lens from the eye. The most common complications that I've observed are inflammatory in nature such as contact lens acute red eye (CLARE) self-limiting responses that are often preventable through compliance.
Dr. Ghormley: GP lenses represent a small percentage of all contact lens patients. What percentage of your contact lens practice is GP lenses? Do you see more or less complications with GP lenses as compared to soft lenses?
Dr. Castellano: About 35 percent of our patient base wears GP lenses. Overall, I would say that we see fewer complications with this modality, though silicone hydrogel lenses have helped close the gap.
Dr. Secor: My GP percentage is around 10 percent to 15 percent, and I would love it higher. I have much higher success with multifocal GP lenses as compared to multifocal hydrogel lenses. We see fewer complications with GP lenses, but comfort in soft lenses is still superior for most patients, and convincing patients of the many advantages of a GP lens is sometimes challenging.
Dr. Smythe: GP lenses probably represent 25 percent of my regular contact lens practice and 75 percent of my specialty lens practice. Optically these materials and designs are superior to soft lenses. Because of high oxygen permeability and tear exchange, the complication rate with GP lenses is very low.
The biggest stumbling block for many practitioners is getting patients through the adaptation phase and addressing initial comfort. Using large-diameter, thinner, aspheric designs helps considerably with adaptation as does using an anesthetic drop at the fitting visit and during dispensing. Simply explaining that the sensation the patient is experiencing is the edge of the lens in contact with the lid and that it will disappear within two weeks can often promote compliance with wear during the adaptation phase.
Dr. Ghormley: Dry eye is a frequent symptom of many contact lens patients. How do you manage dry eye contact lens patients? What type of contact lens do you recommend for a dry eye patient?
Dr. Castellano: The treatment depends on the cause of the dry eye. We've found that many patients report less dryness when wearing a silicone hydrogel lens material. Therefore, this is our material of first choice in such cases.
Dr. Secor: We manage dry eye complications with all available options: Maximize oxygen permeability by refitting HEMA patients into silicone hydrogel lenses, prescribe appropriate lens care products, recommend lubricants, encourage good lid hygiene and insert punctual plugs when needed.
Dr. Smythe: It's important to rule out true pathologic dry eye in these individuals, which is rare for typical lens wearers. Most of these patients experience the symptoms only during lens wear.
I've found that biomimetic materials such as Proclear (CooperVision) and some silicone hydrogels have made significant headway towards alleviating or even preventing dryness symptoms. These materials have many advantages including less on-eye dehydration, enhanced oxygen permeability and superior surface wettability (depending on the material).
Dr. Ghormley: Most multipurpose solutions (MPSs) were developed for hydrogel lenses. Are they effective with silicone hydrogel lenses? Do you recommend the no-rub lens care procedure to your silicone hydrogel patients? Do we need a surfactant cleaner with silicone hydrogel lenses? When do you recommend a hydrogen peroxide lens care system? What rewetting drop do your recommend to your patients?
Dr. Castellano: We generally recommend an MPS approved for silicone hydrogel lenses. However, we strongly recommend to our patients that they include a rubbing step in their lens care procedure. This helps to remove lipids and other debris from the surface prior to lens disinfection. For patients who are hypersensitive, have demonstrated specific problems with MPSs or who have GPC, we recommend a hydrogen peroxide-based system.
Dr. Secor: Silicone hydrogel materials don't act like traditional HEMA lenses with regard to surface chemistry, and therefore some patients react very differently with different lens care products. The no-rub label on MPSs often mislead our patients to think they can't rub their lenses, which can cause complications. Patients can greatly enhance lens comfort and vision by properly using appropriately prescribed care products every time they remove their lenses. Surfactant cleaners, especially those with an alcohol base, greatly reduce lipid deposits and enhance success. Patients who are sensitive to preservatives or who have a history of allergy, GPC or complaints of dryness will benefit from a hydrogen peroxide lens care system.
My preferred rewetting drops are blink (AMO) or Aquify (CIBA Vision). These drops improve wettability and lens comfort.
Dr. Smythe: Silicone hydrogel and lens care solution incompatibility issues have been reported in the literature, and I've observed them in my clinical practice. Whenever I dispense silicone hydrogel lenses, I personally recommend and review a lens care regimen that has undergone testing on these lens materials. It's also critical to review the advantages of digital cleaning with silicone hydrogel lenses. Although they're very protein resistant, they are lipophilic. Passive cleaning such as rinsing and soaking is inadequate in many cases, and physical rubbing is necessary to remove lipid deposits.
For lipid-prone patients, consider adding an alcohol-based solvent cleaner such as MiraFlow (CIBA Vision) to the cleaning regimen.
Peroxide-based systems are advantageous because they are preservative-free, which often helps with symptoms of dryness and incompatibility issues.
I believe you should choose a rewetting drop based on the underlying problem. If the patient truly has a dry eye or is sensitive to MPS, then I recommend either a preservative-free drop or a formulation with a disappearing preservative. These include Refresh Contacts (Allergan) or Aquify (CIBA Vision). For mucin-ball-prone silicone hydrogel patients or those who experience frequent surface deposition issues, rewetting drops with an anionic cleaner such as Clerz Plus (Alcon) or Blink-N-Clean (AMO) are helpful.
Dr. Ghormley: Have you fit patients with the new SynergEyes soft/GP contact lens? What type of patient is a good candidate for this new lens technology? Have you seen complications with this lens? In the near future, this new lens development will have a keratoconus, post-refractive surgery and multifocal lens design. Do you have patients who will benefit from such designs?
Dr. Castellano: I was fortunate enough to be involved in the clinical trials of the SynergEyes single vision sphere and multifocal lens designs. I think this lens offers promise for those patients who have astigmatism and failed with toric soft lenses or who are GP intolerant. Ultimately, these lenses may prove extremely valuable for keratoconus, post-refractive surgery and irregular cornea patients, as well as serve as a platform for a wavefront contact lens.
Dr. Secor: I don't have experience with the SynergEyes contact lens. I'm anxious to have more options for my specialty contact lens patients who need the optical advantages of a GP lens and the comfort of a soft lens. I currently have success fitting a piggyback system using a silicone hydrogel lens and a high-Dk GP lens for my GP intolerant patients.
Dr. Smythe: This is a great design concept, combining the superior optics of a GP lens with a soft skirt to aid in centration and comfort. Where these designs have failed in the past is in material chemistry. Oxygen permeability was inadequate; therefore the major complications were related to hypoxia.
I've used the SynergEyes lens for more than two years, and the applications are very broad. It's useful in fitting irregular corneas such as keratoconus, pellucid marginal degeneration and post-surgical ectasia or oblate surface topographies. We've also had positive experience with the lens for moderate astigmats who prefer the comfort of a soft lens, but have inadequate visual acuity with a soft toric design.
During my early experience with the lens, the most significant complication was on-eye tightening and resultant corneal staining, plus limbal flush. I've significantly improved this with improved fitting guidelines. The lens must fit with apical clearance, and the initial base curve should be at least 0.2mm to 0.3mm steeper than flat K. The appropriate soft skirt radius will provide lens centration with some movement and no edge standoff or fluting. However, during the fitting process, you should focus attention on the GP-to-cornea relationship and on achieving central or apical clearance.
The lens definitely will have a niche for difficult-to-fit patients. However the "A" lens design is indicated for any individual who would benefit from a GP lens.
Newer Technology, Healthier Lens Wear
I would like to thank Dr. Castellano, Dr. Secor and Dr. Smythe for sharing their clinical experience and expertise. By endorsing new contact lens technology our practices will grow, our patients will benefit with better vision and healthy eyes, and the field will continue to expand into the future.
Dr. Ghormley is in private practice in St. Louis, MO. He is a past president of the American Academy of Optometry and a Diplomate of its Cornea & Contact Lens Section.