instrumental focus

Chart Your Course

Mapping system with testing software aids in management decisions.

S. Barry Eiden, O.D.

Imagine a device that not only shows you see the cornea's hills and valleys, but also includes testing software applicable to a majority of patients. Add precision, staff operation, network and EHR integration, and this describes the Keratograph 4, from OCULUS.

Overview

The Keratograph 4 is an objective, non-contact keratometer/placido ring-based, 3D topographer that comes with contact lens fitting software and tear film scan analysis software. (Optional software, described below, is also available.) It provides an overview display of central radii, corneal astigmatism, eccentricity and corneal curvature, among other parameters, corneal irregularity measurements, an indices display for keratoconus progression, Zernike and Fourier analysis and a map comparison mode.

The contact lens fitting software displays simulated fluorescein patterns, aiding you in lens design and selection. In addition, it allows you to either custom design an RGP lens or choose a proprietary lens design from an ever-expanding lens database. Upon lens selection, the software calculates the parameters. Also, the software simulates, via fluorescein patterns, the lens fit, reducing the need for diagnostic fits. The tear film scan analysis software is comprised of non-invasive Keratograph break-up time (NIKBUT) and quantitative tear meniscus height. The NIKBUT component identifies distortion areas on the placido rings measured precisely through time via video capture. Then, it displays the tear break-up time in green (stable), yellow (critical) or red (unstable) for individual segments over the ocular surface and the average break-up time for all points of break-up measured. The tear film quantity is assessed by acquiring scaled photos, which display inferior tear meniscus height data. The test data not only aid in the differential diagnosis of dry eye (evaporative vs. aqueous deficient) and appropriate treatment choice, but also facilitates evaluating dry eye status. (Studies have determined normative values for both tests.) And, the ability to educate patients about their dry eye status has improved patient compliance to treatment(s).

My practice has the full Keratograph 4 package, which also includes pupillometry software (dynamic and static measures) and contact lens oxygen transmissibility software. The latter software, OxiMap, displays a lens' oxygen transmissibility, numerically and in color, across its entire surface based on the lens' refractive power. Also, this software includes a database of the most frequently prescribed soft contact lenses, so you can enter a prescription for each lens and determine its oxygen transmissibility. Because patients can “see” a lens' oxygen transmissibility, it's increased my practice's dispensing of high-oxygen lenses.

Testing procedure

An unstable tear film distorts placido-based topography system images. To preclude this, we have the patient remove his lenses at least five minutes before testing. If the images remain distorted, we stabilize the tear film with low viscosity artificial tears.

Although every software component of the Keratograph 4 works differently, the testing procedure is basically the same. The patient looks into the device's 22 rings while the operator selects the specific software. (Because the device is easy to use and lacks subjective components, my technicians operate it.) Then, the instrument captures the desired image, and the data is displayed almost immediately through our networked computer system into an exam room. Observation can take place at the instrument centrally, which has its own CPU and monitor, or at any networked workstation. The networked software allows manipulation of captured data at any workstation, just as if you were at the central instrument itself.

The Keratograph 4 includes tear film scan analysis software. The data from both tests of this software not only aids in the differential diagnosis of dry eye and appropriate treatments, but also makes it easy to evaluate dry eye status.

Staff training

OCULUS provides representatives to instruct staff on the device's use and output. Generally speaking, reps present for a half-day. Also, OCULUS provides paper and electronic manuals. My staff learned to use the device fairly quickly, though it took them some time to acquire usable images. I think any staff with experience in operating other diagnostic devices should be able to learn the Keratograph 4 in a short period of time.

Return on Investment

Your overall ROI depends on how you use the Keratograph 4. That said, for corneal topography, use CPT code 92025. (Only certain diagnostic codes are covered for topography, such as keratoconus 371.61.) Currently (2011), Medicare reimburses about $35 bilaterally for corneal topography.

For external ocular imaging, use 92285. (This can be considered for non-invasive tear break-up time imaging and for inferior tear meniscus height measures. Again, only certain diagnostic codes cover for this.) Currently, Medicare reimburses about $30 bilaterally for external ocular imaging. For fees not billed to insurance, these procedures may be considered part of a contact lens diagnostic evaluation, part of a dry eye evaluation, etc.

As optometrists, we regularly conduct contact lens fittings, pre-LASIK screenings and make corneal disease, post-refractive surgery and dry eye assessments. Therefore, the Keratograph 4 is a practical addition to one's practice. Also, as shown above, it saves time, facilitates diagnosis and treatment decisions, patient education and improves patient adherence to treatment recommendations. OM