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.
Continuous Wear
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.
GP Lenses
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.
Dry Eye
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).
Lens Care
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.
Hybrid Lenses
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.
Contact Lens Spectrum, Issue: July 2006