IMPROVING CL SUCCESS
Technologies to Improve Contact Lens Success
A look at what’s available to help practitioners evaluate the ocular surface during the fitting process.
By Mile Brujic, OD, FAAO, & David L. Kading, OD, FAAO
We are all aware of the statistics on contact lens dropouts; around 16% (Nichols, 2010) of all contact lens wearers will stop wearing contact lenses this year. Many of them drop out because of discomfort with their contact lenses. But when it comes to making patients comfortable with their lenses, the solution to the problem usually starts with fixing the ocular surface.
In our offices, we see the ocular surface as five continuous structures that must work in unison with each other to allow any patient to have an ideal ocular environment. These five layers are composed of the inner eyelid and eyelid wiper area, the lipid layer of the tear film, the aqueous layer of the tear film, the mucin and goblet layers of the cornea and conjunctiva, and the corneal and conjunctival epithelial layers. When these layers are not synergistic, problems will ensue.
As we have all seen, when we place contact lenses upon this delicately balanced environment, they are certain to cause problems, especially if everything is teetering toward imbalance already. As such, it is crucial for us to look for new ways to evaluate the ocular surface for our patients during the fitting process to maximize our outcome.
Within the last three years, we have had the unique opportunity to gain first-hand experience with technologies and theories that have helped alter our fitting protocols and have enhanced our patient care. We would like to share some of these with you. Although this article doesn’t cover every single technology out there, here are some notable ones that we have encountered.
Tear Film Analysis
LipiView (TearScience) The LipiView machine is an instrument that functions in two ways to evaluate a patient. First, it performs an evaluation of the tear film lipid layer thickness (LLT). At the same time, it performs an evaluation of the amount of blinks and the quality of the blinks.
We have found the LipiView machine to be helpful because it gives us a snapshot as to the thickness of the outermost layer of tears. Obviously, this layer of the tear film is important to decrease evaporation and to keep the tears and lens slippery as the eyelid slides over them. We typically like to see our patients’ LLT to be at least 90nm, but ideally greater than 100nm.
The second function of the LipiView is just as important to us, as it evaluates blinks. As contact lens fitters, we all see the importance of a complete blink over the top of a lens to replenish the entire surface of the lens with a new, fresh tear film.
With LipiView, we are able to evaluate the quality of the blink. It is commonly understood that patients’ blink rates decrease significantly with computer use. With many of our computer users, we have discovered that their blink quality is also significantly decreased. Many of these patients exhibit partial and incomplete blinks.
This can pose a problem for two reasons. First, without a complete blink, the upper eyelid does not make contact with the lower eyelid, and the efficiency of its ability to “grab” tears to pull up is decreased. Second, without the complete blink, we believe that the functional component of the eyelid to express additional lipid from the meibomian glands is decreased.
When both LLT and the number and quality of blinks are decreased, we have multiple areas for improvement with our patients. We initially look for ways to increase the quality of our patients’ blink. We educate them on blinking exercises, making certain to emphasize the importance of the eyelid blinking muscles rather than the eyelid squeezing muscles. In some cases, improving your patients’ blink alone will solve many of their dry eye or contact lens comfort issues, and it will increase their LLT because the eyelid is now carrying more lipid to the ocular surface. But, when it does not, we work to increase the flow of meibum from the meibomian glands.
Meibomian Gland Examinations
Meibomian Gland Expressors (MGE) We have started to use meibomian gland expression during our comprehensive examinations. Meibomian gland expression does not take much time and can tell practitioners a lot about the condition of the glands and the ocular surface. Outside of our slit lamps, we feel that this test is quite possibly the most helpful diagnostic test in our dry eye toolbox.
This procedure can be done in two ways. When using digital expression with our own fingers or thumbs, but without a given amount of pressure, we are left uncertain as to whether the pressure we are putting on the lid is too much (in which case it is not diagnostic for meibomian gland dysfunction) or too little (in which case we are not simulating the blink).
Or, we can use an instrument called a meibomian gland expressor, which places pressure upon the eyelid just anterior to the meibomian glands. This pressure simulates the pressure upon the meibomian glands by the normal blink (1g/mm2 to 2g/mm2) (Miller, 1967).
We look at the number of glands that are producing liquid secretions. If the glands are not producing, then we know that it is time to begin treatment of the meibomian glands.
Meibography Meibography uses an infrared camera to evaluate the posterior side of the eyelid and to image the meibomian glands. Using this instrument, we are able to evaluate the amount of gland loss (gland dropout) that has occurred. The machine utilizes infrared lighting to illuminate and “pull out” the view of the glands so that they can be seen and analyzed for structure and dropout.
Having an understanding of the amount of dropout of a gland helps to understand how healthy a patient’s tears can be. If a patient has little gland expression but meibography shows healthy glands, there is good indication that, with proper treatment, the patient could have good functional tears. However, if a patient reveals significant gland loss, it could indicate that the patient is incapable of producing a good oil layer.
Point-of-care tests have changed the way in which we care for our patients. Tear osmolarity has changed the way in which we think of the chemical composition of the tear film (Versura and Campos, 2013). For example, AdenoPlus (Rapid Pathogen Screening Inc. [RPS]) gives us the ability to assess for adenoviral antigens in our patients presenting with acute red eyes (Sambursky et al, 2013).
Most recently, a new point-of-care test has again challenged the way that we think of the tear film. More importantly, it helps us question contact lens discomfort and strategies for improving lens wear.
Consider a patient whom you have seen over several years and have needed to refit him into a newer technology lens every year because of complaints of dryness. The new lens is successful for awhile, but then the patient begins to feel discomfort with these lenses. The cycle repeats over the years.
We are fortunate to have experienced many advancements in contact lens technologies and to have been able to refit this patient throughout the years. But, are we doing the patient a disservice by not further questioning why the newer technologies into which they are being fit are becoming less comfortable? Is it possible that the quality of the tear film is decreasing over time, causing this patient to wear even the newest contact lens technologies less comfortably? We think that in some patients, this is exactly what is occurring.
InflammaDry (RPS) is a point-of-care test in which a small portion of the test is dabbed along the lower palpebral conjunctiva six to eight times. This collects a sample of tears, which is then tested for the presence of a specific inflammatory marker, matrix metalloproteinase-9 (MMP-9) (Sambursky et al, 2014). This enzyme is a non-specific inflammatory marker that is expressed at higher concentrations in inflammatory conditions of the ocular surface (Chotikavanich et al, 2009; Acera et al, 2013; Kaufman, 2013).
With that said, dry eye disease has increased levels of inflammation on the ocular surface. In one study, the InflammaDry test was performed on patients who were clinically identified as having dry eye, with a total positive agreement of 81%. When the InflammaDry test was performed on the control group of patients who didn’t have dry eye, the tests’ ability to correctly identify such patients, or produce a negative result, was 98% (Samburksy et al, 2014).
We have incorporated this test into our protocol for those patients experiencing contact lens discomfort. If the test results in a positive reading, a further investigation into the type of dry eye and proper treatment approach ensues.
Topography Many of us have topographers in our practices. A number of the newer technologies now incorporate topography as one of a series of measurements that the instrument will perform. There are also other topographers that are standalone technologies in which their sole purpose is topography measurements of the cornea. These are available as placido disk topographers, which have large surfaces that reflect the placido rings off of the corneal surface, and placido cones that come much closer to the cornea to acquire the measurements.
Although this provides much information about the cornea, have we ever considered repurposing the technology for other uses? Lampa et al (2012) were the first to really discuss this, as their group looked at topography measurements over the surface of multifocal contact lenses to determine whether patients were, in fact, looking through the optical centers of multifocal contact lenses and whether there were any differences in four different types of multifocal contact lenses.
They found that the various designs of contact lenses tended to fit very similarly when the different lenses were placed on the same eye. What they also found was that the line of sight in some individuals tends to be nasal to the optical center of the contact lens.
Most simultaneous designed soft multifocal contact lenses have a near-center, distance-periphery design. There is one design that has its distance optics in the center of the lens and near optics in the periphery of the lens. One other design has its distance optics located centrally with alternating near and distance optical zones as you progress toward the periphery of the lens.
What is interesting is that most of the multifocal optical properties of these lenses are located on the front surface of the lenses. This allows topographical measurements over the surface of the lens (Figure 1), which highlights the different optical zones of the lenses. By doing this, you can determine where the line of sight is with respect to the optical center of the lens.
Figure 1. Topography over a near-center multifocal lens on a patient’s right eye. The near center of the lens is located temporal to the patient’s line of sight.
The line of sight may be misaligned with the optical center of a multifocal lens for a number of reasons including a nasal angle lambda, nasal pupil decentration, and temporal lens decentration. Most topographers can measure the distance between the center of the pupil and the line of sight. Additionally, at the slit lamp, you can determine pupil centration within the horizontal visible iris diameter. But, ultimately, a multifocal lens needs to be placed on the eye to determine how the optics will line up over a patient’s line of sight.
So clinically, how does this help improve multifocal contact lens fittings? First and foremost, for those patients who have problems seeing with their multifocal contact lenses, even after the troubleshooting steps in the fitting guide have been performed, it is often the result of a misalignment of the optics of the lens with the line of sight.
If the topography over the surface of the lens clearly demonstrates a misalignment of the optical center of the lens from the line of sight, it allows you to communicate to your patient the likely reason for his reduced near vision. What this does from a practical perspective is provide the patient with a reason why the decreased vision may be occurring.
Previously, without this information, we found ourselves with certain patients not really knowing when to conclude the fitting process, because we weren’t sure why multifocals would be successful with some patients and not with others. Although patient expectations are still an important consideration, with topography measurements over the surface of the lens, you can observe what is occurring optically with the lens and the patient’s line of sight to help provide an optical explanation for successes and failures with multifocal fittings.
A paper presented at the Global Specialty Lens Symposium earlier this year demonstrated that a new type of concept lens that is designed with an offset near center can be aligned with a patient’s line of sight and can significantly improve the patient’s near vision through multifocal lenses (Brujic, 2015).
Anterior Segment Optical Coherence Tomography (OCT) OCT has changed the way in which we manage posterior segment conditions, such as a variety of macular and optic nerve head conditions. For several years, anterior segment OCT has represented an important procedure for those passionate about specialty contact lenses. Where we have had the most utility with anterior segment OCT is in its ability to accurately measure central corneal clearance in our scleral lens wearers.
Traditionally, we measured corneal clearance via the thickness of the fluorescein that was present between the posterior surface of the lens and anterior portion of the cornea. Although we still utilize this measurement to obtain a good initial idea of clearance, exact clearance can be measured with anterior segment OCT (Figure 2). Obtaining the accurate clearance can often help guide you toward a more accurate second lens selection or can determine whether adequate clearance is present with the current lens that is being fit.
Figure 2. Comparison of OCT measured clearance compared to that measured by the slit lamp evaluation.
Anterior Segment Photography Even though anterior segment photography is considered a traditional technology, it still provides an important staple for patient education. Just like all technologies, the anterior segment camera has improved significantly. Essentially, the pictures that are obtained are sharper, easier to acquire, and more detailed because of better optical systems and advancements in computer processor speeds. Additionally, software developments allow realistic videos that help capture what is equivalent to a slit lamp evaluation.
Why is this valuable to a contact lens practitioner? It helps us educate our patients better by allowing them to see what we are actually observing at the slit lamp. In particular, it is helpful for those who are noncompliant or who have conditions that challenge comfortable lens wear that can be seen by a slit lamp evaluation (e.g., giant papillary conjunctivitis).
These conditions can now be easily recorded on video and then shown to the patient to help him understand his condition better. Additionally, if you are following any conditions, you can document the conditions in photographs and compare actual clinical images over time.
Technology has changed the way in which we manage our contact lens wearers. These help us improve the quality of care that we deliver to our lens wearers.
By continuing to embrace these technological advancements and understanding their role in the contemporary practice, we will improve patient outcomes and help more of our patients benefit from the freedom and visual enhancement that contact lenses can offer. CLS
For references, please visit www.clspectrum.com/references and click on document #233.
Dr. Brujic is a partner of Premier Vision Group, a three-location optometric practice in northwest Ohio. He has received honoraria in the past two years for speaking, writing, participating in an advisory capacity, or research from Alcon Laboratories, Allergan, B+L, Optovue, Nicox, Paragon, SpecialEyes, TelScreen, Transitions, Valeant Pharmaceuticals, Valley Contax, VMax Vision, VSP, and ZeaVision.
Dr. Kading owns the Specialty Dry Eye and Contact Lens Center in Seattle. He is the co-owner of Optometric Insights with Dr. Brujic. He has received honoraria for consulting, performing research, speaking, and/or writing from Alcon Laboratories, Allergan, Bausch + Lomb, Biotissue, Contamac, Essilor, Nicox, Oculus, RPS Detectors, TearScience, Valley Contax, and ZeaVision. Follow him on Twitter @davekading.