Article Date: 5/1/2007

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Putting New Contact Lens Technology Into Practice

Learn how to evaluate advances in lens technology. Then prepare your staff, your patients and yourself to implement these new and improved tools.


By Kenneth A. Lebow, OD, FAAO

Over the past 30 years, eye care has changed dramatically. For example, optometry has evolved from primarily an eyeglass-prescribing profession to a medical model in which we treat eye disease, fit complicated contact lenses and counsel patients.

The progression of technology has greatly improved our ability to monitor changes in our patients and provide them with better health and vision care. While some technology is directed toward disease detection (scanning laser polarimetry and optical coherence tomography, for example), other types of technology are simply a progression of earlier measurement techniques (corneal topography and digital anterior segment photography) and are vital to any contact lens practice. Yet, new technology can be daunting to patients, confusing to technicians and expensive for practitioners to obtain and maintain.

In this article, I�ll discuss the instrumentation I feel is essential for a contact lens practitioner. First, however, I�ll offer some insight into how to incorporate new technology into practice.

Educate Your Staff

The first step in adding new contact lens technology to your practice is to ensure that your staff understands and accepts the procedures being performed and the associated fees charged, especially if these are elective tests. Your staff likely will be performing these procedures, and unless they understand the rationale for testing and the benefit of the testing, they can�t communicate this information to patients. While some patients proactively deal with health-related issues and willingly agree to nonreimbursed wellness testing, others are either reluctant to spend the additional money or simply feel they don�t need or want the tests because no immediate problems are on the horizon. A well-educated technician can explain the reason you�re recommending the test and, more important, the benefits associated with the additional data generated.

Wellness testing using procedures that are not covered by insurance is a concept that�s starting to gain widespread acceptance with many physicians who are now recommending that their patients undergo �executive physicals.� Thus, medicine is moving away from being reactive to disease toward being proactive in detecting and treating disease early to ensure good health. Clearly, your practice�s attitude toward health care, be it proactive or reactive, is instrumental in a patient�s acceptance of new technology and related testing.

Educate Your Patients

The next step in communicating the addition of new technology is to explain the intention of wellness testing to patients before they are brought into the pretesting area. In a hightech office, you can accomplish this in the reception area with computer-based programs, such as those available from Eyemaginations or Ocutouch. These videos, which can run continuously throughout the day, explain the testing procedures and also provide examples of the clinical conditions they�re designed to detect.

Offices without this technology can provide written explanations, which can be given to patients when they check into the office (see �Authorization for Diagnostic Ocular Health Tests�).

Your technician should review the specific tests with each patient immediately before they are performed. One advantage of using a paper form is that patients can sign a statement indicating their acceptance of nonreimbursed wellness testing. A signed form confirms that the procedures and fees were explained in advance and acknowledged by the patient�s signature.

Never underestimate the truth in the old saying, �A picture is worth a thousand words,� especially with health-related issues. Your explanations supplemented with data from your hightech instrumentation will show patients that an eye exam is more than a vision test and a prescription for eyeglasses or contact lenses. While these procedures are extremely important to document clinical conditions, the educational benefit to patients is even more important, and patients often are impressed when they see images of their own eyes.

Key Technological Needs: Anterior Segment Photography

In a contact lens practice, the two most significant technologies are corneal topography and digital anterior segment photography. Have you ever tried to describe astigmatism or keratoconus and had a patient nod his head in agreement but stare blankly into your eyes? You know the patient didn�t understand a word you said. If he could see a topography map of his own cornea, however, he would have a better understanding of your explanation about his condition.

Anterior segment photography has evolved remarkably from the earliest film cameras. Digital imaging slit lamps enable us to take photographs and instantly show a patient the cause of a problem. Some even record video, which can help us explain tear film deficiencies in dry eye conditions to patients.

Traditional and disposable hydrogel contact lenses can cause peripheral neovascularization, which is well documented in the literature. This is a silent and frequently progressive complication from contact lens overwear syndrome, due to a lack of oxygen or simply a noncompliant patient.

Neovascularization often can lead to lipid keratopathy and scarring, but convincing a patient this is happening can require a difficult and timeconsuming explanation. As an example, a new hydrogel lens patient came to my office with no complaints. She was wearing her lenses all day and her eyes where white and quiet. However, when I depressed the lower lid, I observed a significant (>2mm) neovascular response. I photographed the condition and explained to the patient the potential complications of leaving it untreated. I also discussed the benefits of using the new generation of silicone hydrogel contact lenses to resolve the problem (Figure 1).

In this situation, I wanted to achieve a healthier corneal response to contact lens wear, and I knew that by getting more oxygen to the cornea, the blood would regress and ghost vessels would develop. My challenge was twofold. I had to convince this otherwise happy contact lens wearer that she was experiencing a complication from wearing her lenses, and I needed to be able to measure the improvement she would realize with the new lenses.

After wearing the new silicone hydrogel lenses for 1 week, the patient returned for her follow-up visit, and I photographed her eye again. Virtually all blood was gone from the vessels, although ghost vessel sheaths could still be seen (Figure 1). The patient was delighted that we discovered the problem before it seriously affected her vision, and she was thrilled that her new lenses resolved the problem so quickly. Photo documentation made this patient an active participant in her own care because she could plainly see the clinical improvement in the health of her eye as a direct result of wearing new lenses.

Anterior segment photography has become a significant tool for demonstrating to patients how clinical issues may affect ocular health. Moreover, many practices that use electronic medical records photograph every patient�s cornea and retina and attach those images to the electronic record for documentation.

Many levels of equipment � from simple to sophisticated � are available. Simple solutions, such as hand-held digital cameras positioned over the slit lamp oculars, can be effective and inexpensive, although possibly less convenient and more cumbersome to use and obtain proper exposures. Stand-alone anterior segment slit lamp cameras, which take advantage of the microscope�s optics to generate more detailed images of the cornea and endothelium are available but can be expensive. Figure 2 is an image created by such a slit lamp system. It shows disruption to the corneal stroma associated with insertion of an intrastromal corneal ring in this keratoconus patient.

Many photography systems also have video documentation capability, which can demonstrate dynamic fluorescein patterns with movement or tear breakup times. An understanding of biomicroscopy, photography and computers is required to appropriately evaluate photography systems.

Key Technological Needs: Corneal Topography

While keratometers are capable of measuring corneal curvatures, a corneal topographer images the majority of the corneal surface, providing thousands of reference points from which various maps can be generated. You can use different mapping strategies to monitor corneal changes and recommend contact lens designs (toric, spherical and aspheric) and parameters (base curve and diameter).

I find corneal topography invaluable for the following applications:

1) Explaining contact lens-induced corneal warpage
2) Describing and fitting for keratoconus
3) Managing complicated postsurgical corneas.

Probably the most difficult condition to describe to patients is contact lens-induced corneal warpage. These patients are usually very comfortable with their lenses and oblivious to their condition, although they may notice some minor vision fluctuations when they change from contact lenses to spectacles and vice versa. We can describe how the cornea�s shape has changed from contact lens wear, but without an adequate comparison to normal corneal geometry and an extensive explanation and demonstration of a problem, patients often are reluctant to change lenses. Once a topography map demonstrates inferior steepening, superior flattening and a change from the normal prolate cornea shape to an oblate shape, the patient starts to get the idea something is wrong with the contact lens fit.

One of my patients had a 20-plus-year history of contact lens wear, including 13 years of PMMA lens wear and, more recently, 7 years of GP lens wear. Within the past 4 years, she had been refit with new lenses, which were never comfortable. The corneal topography map demonstrated severe inferior steepening (over 50.00D), an extremely low prolate shape factor (SF 0.04) and a small central zone of apparent with-the-rule astigmatism, indicating a reversal of normal corneal symmetry, as shown in Figure 3. While the contact lens had a relatively flat base curve-to-cornea fitting relationship, the lens was displaced inferiorly over the nasal limbus and adhered to the cornea without visible signs of movement.

Once the lens was removed, central corneal staining and a compression ring were apparent (Figure 4). A smaller, steeper aspheric lens design was fit in an attempt to restore normal corneal geometry.

When dealing with this type of case, you should generate a difference map showing �before� and �after� curvature patterns, which will demonstrate that the new lens has allowed the cornea to return to its normal shape. Figure 5 shows the change from a radially asymmetric cornea with central flattening and peripheral steepening to a more normal prolate shape with central steepening and peripheral flattening and a more centered contact lens (the area in red).

For more on the utility of corneal topography in a contact lens practice, see �Treating Keratoconus Patients� on page 25 and �Corneal Transplantation Challenges� on page 26.

Confocal Microscopy in Contact Lens Practice

Confocal microscopy enables practitioners to evaluate the minute details of the endothelial cellular mosaic under 185x magnification over a 0.2 mm by 0.4 mm field of view. Studies have clearly demonstrated1 that corneal hypoxia created from hydrogel contact lens wear can disrupt the normal hexagonal endothelial mosaic creating polymegethism (a greater than normal variation in cell size) and pleomorphism (manifesting different forms at different stages of cell life). These changes are subtle. Typically, they are not visible to the clinician, and they may develop long before quantifiably obvious signs of edema, such as neovascularization, are apparent.

Although confocal microscopy often is used before cataract surgery and in Fuch�s dystrophy, it has an obvious application in contact lens practice. Monitoring the integrity of the cornea is vital to ensuring the long-term health of the eye. Obtaining pre-contact lens fitting endothelial cell densities and comparing them to post-fitting values will show the effect of a contact lens on the eye. Refitting hydrogel lens patients with silicone hydrogel lenses may improve endothelial cell densities and reduce polymegethism and pleomorphism. 2 Figure 6 shows the increase in endothelial cell density (labeled �L�) after my patient was refit with a silicone hydrogel material (OD: 1134 to 1554, OS 1603 to 1720). The physical appearance of the cells also improved. When shown to a patient who might have been reluctant to get new contact lenses, this data is convincing.

Patients are concerned about the health of their eyes, so whenever a healthier alternative is available, they usually feel it is the best option. Being able to demonstrate improvement is an added bonus. Embrace New Technology Modern technology plays an important role in a contact lens practice. By evaluating and detecting corneal conditions earlier in their development, we can intervene with therapies before the conditions are too advanced. Modern technology also enables us to understand changes from normal and to educate patients about the clinical issues affecting their corneal health. Technology enables us to charge additional fees and bill insurance companies for medically related diagnoses, which generate additional income.

When considering new technology for your office, determine 1) that it will help you provide better patient care, and 2) that you will realize a reasonable return on your investment. Once these criteria are met, explaining the need and rationale for the testing to your staff and your patients is critical to ensure successful implementation of new procedures in your office.

One lesson I have learned is that not only has new technology in the contact lens, glaucoma and retina fields made me a better practitioner, it has increased my medical billings because I am finding more clinical concerns that require additional testing and professional evaluation. So get involved with the new technology, educate your patients and watch your practice grow.

REFERENCES
1. Schoessler, JP. Corneal endothelial polymegethism associated with extended wear. Int Contact Lens Clinics. 1983;10:144.

2. Edmonds D, Pemberton B, Bullimore M, et al. Endothelial Morphology 1 Year After Refitting Hydrogel Lens Wearers With Lotrafilcon A Silicone Hydrogel Lenses. Poster presented at 2004 meeting of American Academy of Optometry, Dec. 9, 2004, Tampa, Fla.



Treating Keratoconus Patients

Keratoconus patients have unique corneal geometry, with areas of corneal thinning, keratometric steepening and significant irregularity. Diagnosing early keratoconus is difficult without a corneal topographer.

An interesting case involves a family with a clear genetic inheritance pattern of this corneal dystrophy. It starts with two brothers, both with keratoconus. One required transplantation while the other continues to wear aspheric GP contact lenses despite significant corneal scarring. The brother wearing the lenses has three children, two girls and a boy. The oldest girl developed keratoconus in her mid- to late teens and, because her eyes were very sensitive, she is wearing SoftPerm lenses with significant success. The other daughter, as a preteen, was examined and found to have an irregular retinoscopic reflex, normal corneal curvatures, 20/25+ visual acuity and no visible biomicroscopic signs of keratoconus. At that time, prior to development of corneal topography, the parents were told keratoconus was not evident.

Several years later, when corneal topography was performed, it was readily apparent that the younger daughter had developed a forme fruste, or subclinical version, of keratoconus,
and it was clearly progressing. The image above shows a trend display plotting the progression of this corneal ectasia over 4 years. It illustrates the progressive enlargement of inferior steepening along with the widening area of the ectasia. Ultimately, this daughter also was fit with contact lenses to correct her keratoconus.

For many years, the youngest child showed no evidence of keratoconus (slit lamp or topography). However, recently, he too demonstrated inferior steepening and superior flattening and is being fit with GP lenses to correct his vision.

While this family has a strong genetic predisposition to keratoconus, without the use of corneal topography, the diagnosis would have been significantly delayed, resulting in many spectacle corrections and frustrations for the patient. In fact, the grandchildren of the original patient are now being brought into the office for corneal topography mapping to rule out keratoconus.


Corneal Transplantation Challenges

Corneal transplantation is one of our most challenging contact lens fitting situations. Depending upon the surgeon�s expertise, the graft may have a prolate (steeper in the center and flatter in the periphery) or an oblate shape (flatter in the center and steeper in the periphery). The cornea may be spherical or astigmatic and, if astigmatic, it may be orthogonal or nonorthogonal (distorted). Other possible topography patterns include a mixed prolate and oblate shape, asymmetrical toricity and a general steep-to-flat curvature.

Regardless of shape, an elevation map is the ideal topography to use when judging how a contact lens will fit on a transplanted cornea. Prolate corneas are typically the easiest to fit, because they represent a more normal corneal geometry. Oblate corneas can be fit with reverse geometry GP or hydrogel lenses so the contact lens base curve more closely matches the corneal shape. This often will reduce or eliminate edge standoff problems. Since most transplanted eyes have moderate to excessive amounts of corneal toricity, patients usually need toric base or bitoric GP lenses.

The images above show the relationship between the elevation map and the contact lens fit on an eye with more than 20D of corneal astigmatism. The red areas on the map represent areas of elevation over the reference sphere and correspond to the areas of touch on the contact lens fluorescein pattern. The inferior area of blue represents a depressed area relative to the reference sphere, and since it is so great, the lens edge actually stands away from the corneal surface.

Topography and anterior segment photography technology allow us to visualize this problem and correct it before ordering a contact lens.



Contact Lens Spectrum, Issue: May 2007