Using Instruments To Improve Your Contact Lens Success
Five contact lens experts discuss instruments that they have found helpful when fitting contact lenses.
By Judith Lee
There's no question that the right tools can improve your success with fitting contact lenses. But what tools, and how do they help? We asked a panel of distinguished contact lens practitioners (Melissa Bailey, OD, PhD; Peter D. Bergenske, OD, FAAO; David A. Berntsen, OD, MS; Timothy T. McMahon, OD, FAAO; and Lee E. Rigel, OD, FAAO) to each identify an instrument that they find helpful and to discuss how they use the instrument in practice.
From taking more objective measurements (autorefractors) to providing important baseline information (pachymetry) to identifying and documenting corneal changes or abnormalities (topography, imaging, aberrometry), instruments offer a host of overall benefits for lens fitters.
Pachymetry has become the standard of care for glaucoma patients, but it's also useful for contact lens fitting, says Dr. Rigel. He uses pachymetry to obtain baseline readings for every contact lens patient. "As a baseline measurement, pachymetry can give you insight into potential problems down the road," he says. It also helps in managing ocular disease, keratoconus, glaucoma, Fuchs' dystrophy and LASIK patients.
Corneal topography is an important problem-solving tool, says Dr. McMahon. "Topography is capable of displaying even subtle abnormalities and changes in corneal curvature. Such information can define the origin of and explain changes in vision," he says. In addition, most topographers feature software that can help you fit GP lenses.
Wavefront aberrometry may be the most leading edge technology, and it's also becoming more commonplace, says Dr. Berntsen. "Many researchers are currently examining the possibility of developing soft prism-ballasted lenses that can correct the higher-order aberrations of both normal and keratoconic eyes. Soft spherical lenses with aspheric front surfaces that are designed to correct spherical aberration, and thus improve retinal image quality, represent the first attempts at incorporating aberration correction into contact lenses." Examples of such lenses include CooperVision's Frequency Aspheric, CIBA Vision's Choice AB and Ocular Sciences, Inc.'s Biomedics Premier.
Improving Fitting and Follow Up
Topography and aberrometry are geared more for special or problem cases. For standard contact lens fitting and follow-up, more tried-and-true technology is most helpful.
An autorefractor will save you time whether you're fitting contact lenses or troubleshooting a current patient, says Dr. Bailey. This instrument provides better objective readings, and a trained technician can easily use it.
"Many autorefractors will provide a printout of multiple refraction measurements, which can help diagnose problems with variable vision in patients who wear more complicated lenses such as soft torics. For these lenses, multiple autorefraction measurements (taken quickly) over the contact lens may show a wide range of refractive error measurements on the printout, which would indicate that the lens is probably rotating with the blink," says Dr. Bailey.
Pachymetry is another tool for managing existing contact lens patients, particularly extended wear patients. "'Myopic creep' of about 0.25D per visit can occur in high myopes on an extended wear schedule. Some of these patients are actually experiencing corneal edema. You can determine this if you have good pachymetry baseline readings," says Dr. Rigel.
He notes that by switching extended wear patients into a high-Dk lens, you may find that myopia will decrease. "Pachymetry may offer you an explanation for the myopic increase and enable you to differentiate myopic creep from true myopia."
Tackling Special Cases
For specialty lens fitting, our experts say that technology is a must to fit patients who have special problems, manage their cases more effectively and document their care comprehensively.
For instance, having a "map" of the corneal surface will assist you in fitting GP lenses, says Dr. McMahon. "In many parts of the world, particularly Asia, orthokeratology is topography driven and so it's essential. I agree that topography is important when fitting ortho-k patients, and I think it's also helpful in follow-up situations," he notes.
Dr. Berntsen says that wavefront aberrometry can help you unravel some of the most difficult contact lens cases. "It's a tool that could help explain why some patients can see 20/20 on Snellen acuity charts, yet complain that their visual quality isn't adequate or acceptable. Because higher-order aberrations cause a reduction in low-contrast visual acuity, and because most clinicians typically don't measure low-contrast visual acuity, an aberrometer could in special cases help determine if higher-order aberrations are the culprit in degrading image quality for these patients," Dr. Berntsen explains.
Dr. Bergenske says that you could use digital photography routinely, but it's most helpful for special cases. "This technology is of greatest value for problematic patients, either for documenting abnormal findings or as an effective patient education tool," he explains.
Who Needs Them?
Our experts believe that instruments are a good investment, not just because they can improve your contact lens practice, but because they enable you to serve many more types of patients.
"You can use an autorefractor on all patients regardless of whether you are fitting them with contact lenses. A technician can obtain the measurement during pre-testing, and the clinician can then use that information to more efficiently complete a subjective refraction and/or a problem-focused exam. It's also helpful for any patient who may give variable, inconsistent or unreliable responses during subjective refraction," says Dr. Bailey.
Pachymetry is another tool that can help many types of patients, says Dr. Rigel. "If you diagnose and manage ocular or corneal disease, fit continuous wear lenses or care for glaucoma patients, then you need this instrument," he says.
He finds it indispensable for screening and managing LASIK patients. "To determine if a patient is a candidate for LASIK, you must have a corneal thickness measurement. The surgeon will remove 12µm of tissue for every diopter of change. With a 160µm flap thickness and a 250µm bed thickness, a five-diopter myope would need a corneal thickness of at least 470µm for the procedure. A pachymeter can help you evaluate whether the patient has enough corneal thickness to even consider LASIK.
Dr. Rigel also uses pachymetry for corneal reshaping patients. "You can actually measure central epithelial thinning and thickening in the mid-periphery," he says.
Imaging can also benefit a wide array of patients whose conditions require documentation. For any eye disease or condition, you can meticulously document and easily assess any ocular changes. Experts also say that nothing can help you teach patients about their eyes better than digital photography. "It's impressive to patients and can become a practice-building tool as well," notes Dr. Bergenske.
Improvements Make a Difference
If you previously thought that instruments weren't worth their expense, then be aware that manufacturers have improved and upgraded all of the instruments that the practitioners in this article mention.
Dr. Bailey says, "A clinician who sees a number of postoperative corneal refractive surgery patients would want to invest in an autorefractor that uses a narrow beam diameter. Clinicians should also consider how easy the instrument is to use in their primary area of patient care. I prefer instruments that will print out a number of measurements because I can then see how much variability exists in the multiple refractions. Instruments that print out only an average can hide a variable measurement."
Manufacturers have conveniently downsized pachymeters, according to Dr. Rigel. "Today you can purchase a hand-held pachymeter that fits into a coat pocket. The instrument in our office is several years old, but we can easily move it from room to room. It's quick and easy to use. I can take five readings in three or four seconds. Reproducibility of the instrument is remarkable, even with multiple practitioners using it," he notes.
Digital photography and aberrometers have become more accurate and available. The associated computer hardware has also become more affordable, and it enables an instant display of photos, says Dr. Bergenske.
Newer aberrometers also have much better resolution. "Many companies now offer instruments that are repeatable and reliable, with excellent resolution that allows for a more complete description of the aberrations of the eye," says Dr. Berntsen.
Dr. McMahon notes that the Orbscan II (Bausch & Lomb Surgical/Orbtek) offers both pan-corneal pachymetry and posterior-corneal shape analysis. But in the corneal topography arena, "Mostly what we've seen is shift in who the big players are. One of the toughest jobs practitioners have in purchasing a topographer is predicting which companies will be around in five years," he notes.
Balancing Fees and Reimbursement
As always, third-party reimbursement is a spotty subject. Often, you receive no coverage when you use instruments for contact lens patients. But, you can receive reimbursement when you use instruments to diagnose and manage eye disease and conditions.
"You can't bill third party payers for contact lens-related instrument applications, but you can bill them when you use pachymetry for glaucoma, Fuchs' dystrophy and keratoconus patients. They'll pay for glaucoma just once, and the reimbursement in my state is about $14. We charge $16 to patients when we perform pachymetry, whether insurance pays for it or not," says Dr. Rigel. He notes that the technology is impressive to patients, and they rarely object to a fee that's under $20. Patients are comfortable with the idea of a baseline reading and tend to remain more loyal to the practice when they know you have that kind of data, Dr. Rigel says.
The topography story is somewhat similar, according to Dr. McMahon: "I believe insurance companies will pay for topography only after a corneal transplant," he says.
Many Happy Returns
In general, our panel of contact lens experts agree that technology pays for itself. You can charge a separate fee, receive insurance reimbursement or simply incorporate it into your comprehensive fee, not to mention that the capabilities you gain as a clinician will pay off with an increased caseload and/or improved patient loyalty.
"I think autorefractors would save all practitioners a great deal of time when caring for any type of patient, including contact lens patients," Dr. Bailey says.
Dr. Bergenske says that digital imaging brings a "wow" factor to your practice. "In a practice setting, I think its impressiveness earns enough return in patient referral," he says.
Corneal topography has already achieved a niche with progressive practices, and Dr. McMahon says that his patients have no problem paying a fee for this technology: "I charge a separate fee each time I collect topography data from a patient. I use it frequently in our practice. It's moderately expensive technology, but it pays for itself."
Ms. Lee has been reporting on the vision industry since 1979. She operates a communications consulting firm in Atglen, PA.
Dr. Bailey is a Postdoctoral Fellow at The Ohio State University College of Optometry.
Dr. Bergenske, a Past Chair of the American Academy of Optometry's Section on Cornea and Contact Lenses, is on the faculty at Pacific University College of Optometry.
Dr. Berntsen is an MS Contact Lens Fellow graduate and PhD candidate at The Ohio State University College of Optometry.
Dr. McMahon is a professor and Director of the Contact Lens Service at the University of Illinois at Chicago Dept. of Ophthalmology & Visual Sciences.
Dr. Rigel practices in E. Lansing, MI.