There is no shortage of new diagnostic technology at optometry’s disposal. It seems every month a new device is available to enhance our practice and patient care. And with each new device, we will have to ask the same questions: Will it pay for itself? How much does it cost? Can I afford it? Let’s face it, the last thing any of us needs is a piece of equipment sitting idle in the corner collecting dust, and along with it our simmering anger at the fact we're paying through the nose for that white elephant.
It has been 20 years since optical coherence tomography (OCT) was first introduced for the diagnosis and treatment of eye disease. I became infatuated with OCT while serving as a center director at a comanagement center. The technology is nothing short of amazing: imaging the retina in ways previously unknown. Suddenly I could see things that a fundus photo really didn't do justice. All those layers of the retina I had to learn in optometry school were now actually there to be seen!
Now, once again in private practice, I’ve often thought how great it would be to have that technology available in my office, but the cost for the device was just simply out of my reach. Another fact that adds to value: OCT technology has moved beyond just imaging the retina. OCT can now image the anterior segment and cornea, opening up new areas of diagnostic possibilities. As Dr. Larry Alexander often says, “OCT is a poor OD’s MRI of the eye.” I recently had the opportunity to test drive two of these new devices in my office.
With the release of its new iScan device, Optovue has brought affordable OCT imaging to optometry. The device is a self-contained spectral domain OCT that is small, powerful, and portable.
Optovue iScan uses 26,000 A-scans per second to produce images with axial resolution of 5 μm and transverse resolution of 15 μm.1 The machine’s 3D retina scan with en face analysis enables virtual dissection of the retina by displaying three different reference planes: internal limiting membrane, inner plexiform layer, and retinal pigment epithelium. The device also scans the traditional optic nerve head for nerve fiber layer thickness and the thickness of the ganglion cell complex (GCC). The device’s 3D disc scan shows the optic nerve in cross section and gives a representation of the relative thickness of the selected slices, and the ganglion cell complex analysis aids in identification of ganglion cell loss, which can precede retinal nerve fiber layer loss (Figure 1).
The device is designed to give OCT images of the retina, optic nerve, macula, and ganglion cell complex in an easy-to-operate system. With the anterior chamber attachment, the operator can gain images of the anterior segment and anterior chamber angle, again useful in our diagnosis of glaucoma patients. The device provides pachymetry mapping with full 6 mm diameter corneal thickness mapping with maximum thickness indicator and angle visualization and measurement.
The device is designed to be operator friendly—meaning it doesn’t take a highly-skilled operator to obtain quality images. Voice prompts guide the patient through the entire process. My tech enters the patient data, positions the patient at the machine, and presses the start button. Then she can then move on to another task while the system guides the patient through the entire scan.
Another feature of iScan is iWellness exam, a non-reimbursable scan designed to give a quick retinal image prior to the actual exam, which gives the doctor an initial view of the retina before the patient ever sits in the exam chair (Figure 2). The iWellness scan is very accurate; it boasts 95 percent sensitivity and 99 percent specificity.2
Optovue iScan is fully self-contained and compact with built-in PC and touch-screen LCD. The only complaint I had with the device is there is no chin rest for the patient. The patient must place her cheeks into the aligned areas on the faceplate and remain there for the short length of the scan.
Next: Cirrus 500 review
Cirrus 500 review
I also test drove Zeiss Cirrus HD-OCT 500. Like iScan, this is a compact machine. The manufacturer touts Cirrus 500 as being “the essential OCT with the technology to power today’s comprehensive practice.” The Cirrus HD-OCT model 500 is “specifically designed to deliver a carefully constructed set of sophisticated applications that build upon one another to deliver rapidly-evolving diagnostics for multiple patient populations.”3
Related: OCT in pediatric eye disease
Unlike iScan, Cirrus 500 possesses a chin rest but requires more participation by the operating technician. The device can generate a tremendous number of scans. Glaucoma applications include retinal nerve fiber layer (RNFL), optic nerve head (ONH), ganglion layer, and angle analyses. State-of-the-art technology ensures the Early Treatment Diabetic Retinopathy Study (ETDRS) and ganglion cell and inner plexiform layer measurements are centered on the fovea.4
The machine also generates 3D data cubes, depicting each retinal layer. The data is registered with data from prior visits, which enables side-by-side visualization of the same retinal location for each visit. Cirrus 500 compares measurements from the current and prior visits to provide a thickness change map that helps to determine the next steps in treatment.5
For screening, I used macular thickness and optic disc cube settings. (Figures 3 and 4) This requires the operator to toggle back and forth between the two scans.
Next: Cost considerations
Both machines are available for purchase, and either unit costs roughly $40,000. If purchasing the unit doesn’t interest you, Optovue offers a pay-per-click option for iScan, while Cirrus 500 is available for lease, which includes software updates.
OCT carries three CPT codes (see CPT-4 codes for OCT), and reimbursement in my area is approximately $40 for each procedure.
So, how much instrument can I afford? Most practitioners require diagnostic instruments to provide a financial return on investment to justify the equipment’s purchase. One quick and dirty method to calculate that is divide the monthly payment by reimbursement per procedure, which will tell you how many procedures you must do per month. In a typical general ophthalmology practice, OCT tests are used in around three percent to 12 percent of total visits.6
Yet, that is not a true account of the machine’s cost. Other factors need to be considered, such as staffing and training, physical area needed for the machine, and more. There is a formula called the “contribution margin,” which can tell you how much revenue you really need to bring in to cover the machine’s cost.7 For most optometric practices, that factor will be about 1.8 times the cost of the instrument.
Another axiom is that loan payments should not exceed four percent of your monthly collections. I believe any instrument should pay for itself in billing every month it is used. If it doesn’t, you’re going to feel very bitter about the machine when it sits unused in the corner of the office. Cash flow in an optometric practice is not always sufficient to service a high-expense piece of equipment like OCT, so in some cases leasing makes sense.8
Another way to make the purchase price more palatable is to form a partnership with other like-minded optometrists in your area in an equipment-sharing program. The machine revolves among offices in a prearranged fashion with the cost divided in proportion to the number of days the unit is in your possession. Or consider working with your local co-management center to split-bill OCT procedures—the center bills for the technical component and the referring OD bills for the professional component.
OCT raises the level of patient care
As optometry moves toward a full-scope medical practice model, OCT will become standard of care. All of us can’t help but want more toys for our practice. I personally believe you never buy an instrument just because it can generate income. It has to be a useful and necessary tool to aid in patient care. Will it aid in diagnosis or treatment, and will it raise my level of care for my patients? In the case of optical coherence tomography, the answer is a definite yes.
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2. Awad C, Sloatnick S, Nath S, et al
. iVue iWellness Exam has high sensitivity and specificity. IOVS
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4. Costello F. OCT technologies: Which machine do you want to own? Presented at: North American Neuro-Ophthalmology Society 40th Annual Meeting; 2014 Mar 1-6; Rio Grande, Puerto Rico.
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6. Stahl S. Putting the squeeze on OCT fees. Ophthal. Manag.
Available at: http://www.ophthalmologymanagement.com/articleviewer.aspx?articleid=105041
. Accessed 11/19/15.
7. Sorrenson L. Buying instruments: New toy or valuable treatment tool? Rev Optom Bus
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8. Jens SA. Intelligent investing: Crunch the numbers – and analyze your patient base. Rev Optom Bus
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. Accessed 10/2/2015.