Article Date: 4/1/2009

Corneal Topography Benefits
topography

Corneal Topography Benefits

You should consider integrating this device into your practice for four reasons.

DIANNE M. ANDERSON, O.D., F.A.A.O., Aurora, Ill.

Many practitioners don't employ a corneal topographer because they don't want any part of the chair time associated with specialty contact lens patients (i.e. those with astigmatism, keratoconus, pellucid marginal degeneration [PMD], contact-lens ectasia, post-surgical issues, etc.). The time these patients require, they reason, outweighs the benefits to their practice. As someone who performs numerous specialty contact lens fits, I can tell you that this thought process is non-productive.

In fact, here are four reasons you should consider adding a corneal topographer to your arsenal of diagnostic equipment.

1. Specialty lens wearers produce large profits

The fitting fees and cost of lens materials tend to be higher for specialty contact lens patients vs. standard contact lens wearers by virtue of these patients' corneal abnormalities. A corneal topographer enables you to both diagnose and fit these patients. (See "Applicable Diagnostic And Procedural Codes," below.)

Applicable Diagnostic And Procedural Codes
ICD-9 CODES
367.22…Irregular Astigmatism
371.50…Corneal Dystrophy, Unspecified
371.52…Other Anterior Corneal Dystrophies
371.61…Keratoconus, Stable
371.62…Keratoconus, Acute Hydrops
371.20…Corneal Edema, Unspecified
371.24…Corneal Edema Secondary to Contact Lens Wear
371.82…Disorder Secondary to Contact Lens Wear (not edema)

CPT CODES
92015…Refraction, Refractive Visit
92070…Contact Lens Fit for Treatment of Disease/Lenses Supplied
92310…Contact Lens Design, Fit and Follow-up (Non-Aphakic)
92325…Contact Lens Modification/Supervision of Adaptation
92326…Replacement of Contact Lens
92025…Corneal Topography

CONTACT LENS MATERIALS
V2510…GP Spherical
V2511…GP Toric
V2513…GP Extended Wear
V2520…Soft Spherical
V2521…Soft Toric
V2531…Soft Extended Wear

For instance, the axial/sagittal map of a corneal topographer enables you to properly identify a patient's astigmatism as limbal-to-limbal or apical, with-the-rule or against-the-rule, oblique or irregular. Then, the device allows you to obtain an accurate measurement of the patient's Horizontal Visible Iris Diameter (HVID), so you can fit the most appropriate custom soft toric lens. The average cost of a soft toric lens is $100 to $150 per eye, while the average cost of a custom toric lens is $200 to $275 per eye. Also, the average fitting fees associated with a standard soft toric lens are $85 to $100, while the average fitting fees for a custom toric lens are $150 to $200.

In addition, a corneal topographer enables you to diagnose keratoconus, PMD or contactlens-induced ectasia and use the cornea's peripheral contours to ensure that the dynamics of the GP lens you choose are physiologically compliant with the underlying cornea (see the photos below). Also, most corneal topographers allow you to virtually create a contact lens design via simulated fluorescein (NaFl) patterns. The average cost of a standard GP lens is $100 per eye, while the average cost of a custom GP lens is $200 to $300. Further, the average fitting fee associated with a standard GP lens is $100, while the average fitting fee for a custom GP is $150 to $200.






Axial topography maps allow you to differentiate conditions such as — from top to bottom — keratoconus, PMD and corneal warpage. These diagnosis will help you expedite a treatment plan for the patient.

In addition, a corneal topographer allows you to offer patients the option of corneal reshaping. Patients unable to undergo refractive surgery due to thin corneas or dry eye; those simply looking for an alternative to the procedure; or myopic children and adolescents interested in avoiding daytime spectacle or contact lens wear are attracted to this modality.

Also, the future of corneal reshaping looks promising. This is because new lens designs, such as astigmatic and presbyopic lenses are preparing to come to market.

Although certification is required for corneal reshaping, the courses are well worth the few hours of time required. As several corneal reshaping lenses are currently available on the market, making a design choice can feel overwhelming. Therefore, should you decide to expand your contact lens practice by offering this service, consult with the vendors and distributing laboratories of corneal reshaping lenses to assist you in selecting the designs best for your practice. (Visit www.Paragoncrt.com, www.BERetainer.com and www.bausch.com for more information on corneal reshaping.)

2. Specialty lens wearers are very loyal

Unlike standard contact lens wearers, specialty contact lens patients tend to be the most compliant to both making and presenting for their scheduled follow-up visits and wearing their lenses as prescribed due to their special visual and lifestyle needs. This is an added bonus to your practice's bottom line.

As a result of working with these patients, I've achieved unparalleled patient satisfaction, which has led to loyalty and referrals.

While all patients stay with a practitioner who can solve their problems, these patients appreciate you even more, as they realize their problems are unique.

3. Several specialty lens candidates exist

If you don't think enough specialty lens candidates exist to make the chair time worth your while, you're wrong. Internally and externally advertise your ability to fit challenging patients and offer corneal reshaping, and you'll soon discover an extremely large number of patients interested in these services.

Personally, I've received and continue to receive several e-mails from patients inquiring whether they can achieve success in specialty lenses. These patients have located articles I've written on the subject through Internet searches. If this isn't an indication of how passionate and determined patients are to free themselves of spectacles and achieve successful contact lens wear, I don't know what is. The bottom line is that these patients are willing to try if you're willing to try. (See "Choosing a Topographer," below.)

Choosing a Topographer
Numerous manufacturers and models of corneal topographers exist. Therefore, you must understand the applications and limitations of the available devices before purchasing one.
The two types of corneal topography systems are Placido disc and slit-scanning devices. The majority of corneal topographers are Placido disc systems, which project numerous concentric rings on the cornea and directly measure the anterior curvature. Slit-scanning devices use light rays to scan the entire cornea, which directly measure the elevation of both the anterior and posterior surfaces and generate corneal thickness data.
If you're interested in the anterior corneal surface detail for diagnostic and fitting purposes, you would benefit from a Placido disc system. If you're interested in both the anterior surface and posterior surface detail — the latter for the purpose of evaluating the cornea's health for refractive surgery candidacy — you would benefit from a slit-scanning device.
The Basic features of both systems include axial and refractive maps, tangential maps, difference or subtractive maps, elevation maps and contact lens-fitting programs. Advanced features include video imaging, detailed map analysis and/or Zernike analysis/wavefront aberrometry.
The currently available placido disc systems are the ATLAS 9000 (Carl Zeiss Meditec); CTS (Reichert); Easygraph/Keratograph (Oculus); KR-8000PA/KR-9000PW (Topcon); Magellan Mapper/OPD-Scan (Nidek); 3-D Wave (Marco); Medmont E300 (Medmont Intl.); ReeSeeVit (Veatch); Scout/Keratron (EyeQuip); and the TMS-4 (Tomey USA). The currently available slit scanning devices: Orbscan (Bausch & Lomb) and Pentacam (Oculus).
Each corneal topographer model differs in the quality and detail of the images produced. Models with high-resolution and a large number of data points generate more detailed maps.
Prices vary according to features and detail. Some manufacturers price their corneal topographers with or without the required laptop or desktop computer. Also, you may need additional software to perform functions, such as pathology detection and custom GP lens designing. Further, most corneal topographer manufacturers require licensing of review software for networking purposes. These software upgrades, however, are usually sold separately.
If you're just getting started with corneal topography and don't own an autorefractor or autokeratometer, you may want to purchase a device that combines autorefraction and keratometry with corneal mapping software. In addition to performing three duties, these models save space. Before making any purchase, however, talk with your colleagues, check out the manufacturers' Web sites and instrument buying guides.

4. Corneal topography retains patients

When you send patients who have questionable astigmatic refractions or irregular keratometry readings to another practitioner, you give them the impression that you're not up to date on the latest technology and therefore unable to provide them with the best care. This means they may stay with the referred practitioner not only for their contact lens needs, but also for their future ocular issues, such as cataracts and glaucoma. Retaining patients is more important than ever considering the current economic environment.

As you can see, employing a corneal topographer offers several benefits that outweigh the chair time associated with specialty contact lens patients. Therefore, it's time you conduct research into implementing this device. Talk to colleagues who use a corneal topographer, ask the representatives of the various specialty contact lens companies about how you can become adept at fitting their products, and begin asking patients whether they, a family member or friend would be interested in specialty wear. I think you'll find that an untapped demand exists for specialty lens services. I know I did. OM

Dr. Anderson practices in suburban Chicago, specializing in orthokeratology, keratoconus, post-surgical lens fits and anterior segment disease. E-mail her at dianne.anderson@comcast.net.


Optometric Management, Issue: April 2009