Versatile System Provides Early Detection, More Data
Tight grid patterns, 3-D retinal thickness mapping are highlights of new diagnostic imaging system.
ROCHELLE NATALONI, CONTRIBUTING WRITER
The typical retina practice tends to welcome the newest diagnostic and imaging equipment because of the inherent benefits of cuttingedge technology, such as improved treatment outcomes and practice efficiency. But equally important to retina practices is the diagnostic and imaging equipment employed by the general ophthalmologists from whom patients are referred.
Once these patients are examined and treated by the retina specialist, they tend to return to the generalist and often a comanagement-like relationship ensues. Because of this, some suggest that it behooves the general ophthalmologist to have equally sophisticated retinal imaging equipment. Others think that the generalist’s budget is better spent on diagnostic devices that complement those of the subspecialist.
The RTA 5, a new early detection and imaging system, made by Talia and marketed exclusively by Marco Ophthalmic (both Jacksonville, Fla), may provide a solution by being equally at home and useful in either the subspecialist’s practice or the generalist’s office.
The RTA 5 is the newest generation of the retinal thickness analyzer (RTA) platform.
“The RTA 5 is 6 to 30 times more effective at finding peripheral pathology than anything else that is currently available,” says Michael Crocetta, director of Marco’s Retina Division. “Right now, OCT resolution can’t be beat within a static section,” he adds, “but it fails in its ability to find pathology dynamically — especially if it’s out in the periphery, which is where we want to catch it first.”
The RTA 5 incorporates significant enhancements to the earlier generation, including a nonmydriatic scanning process, higher fundus image resolution, and a new “Vision Wellness” exam. Ophthalmologists interviewed for this article say the RTA 5 distinguishes itself from other retina diagnostic tools with its versatility. It integrates 2 diagnostic pathways: high-resolution digital fundus imaging and scanning laser ophthalmoscopy (SLO) for early detection, diagnosis, and progression analysis of
pathology involving the macula, perimacular, optic nerve head, and peripapillary regions of the retina. Among its features are: its ability to provide 72° x 60° digital fundus imaging with up to 9.4 megapixel resolution; SLO slit image viewing; retinal nerve fiber layer analysis; and peripapillary and optic nerve head analysis with rim/cup measurement, as well as retinal thickness analysis at over 1400 locations and dynamic 3-D anatomy imaging through all real slit sections. Automated progression analysis with deviation probability reporting and additional user-defined custom field testing — which increases the number of thickness measurements to more than 4200 defined retinal locations — are also part of the package (Figure 1).
The RTA 5 takes a series of high-resolution digital fundus images in 0.33 to 0.48 seconds, simultaneously with each SLO scan. Crocetta emphasizes the importance of this capability with this hypothetical question: “If the device that you had didn’t allow you to visualize all real retinal slits, then how would you, or more importantly your technician, be able to discern artifact or false positive data?” The simple answer, Crocetta says, is if you can’t, then you’re just hoping your machine is giving you good data. “Real slits are the only way to judge,” he says (Figure 2).
THE VERSATILITY FACTOR
New York ophthalmologist Ronit Kahanowicz,MD, says, “The RTA 5 does a lot of things well. It takes decent fundus photos, so if you don’t have a fundus camera you can use this to capture a good image. It creates a useful nerve topography map, it measures retinal thickness really well, and it does slit images similar to OCT, except that nerve layers of the retina are not clearly defined,” says Dr. Kahanowicz. “I’ve discussed this with several of my retina colleagues, pointing out the benefits.”
The machine automatically aligns each image based on the patient’s vascular patterns. This, says Dr. Kahanowicz, affords increased accuracy and repeatability because patient fixation is essentially removed from the equation. Dr. Kahanowicz is in the process of evaluating the RTA 5, having relied successfully on an earlier generation RTA system for several years. On the plus side, says Dr. Kahanowicz, is the RTA 5’s increased user-friendliness and speed. “There are several real improvements in terms of getting the scan,” says Dr. Kahanowicz. “It’s a bit more comfortable for the patient to sit at, light intensity is reduced, and the data acquisition time is faster, even though it gathers more data than its predecessor. The benefits are significant: less time and discomfort for the patient and potentially less out-ofpocket expense for the ophthalmologist because speedy diagnostics can equal less overhead,” she says.
Crocetta says speed is an important benefit of the RTA 5. “The scanning times are much faster, with the RTA 5 scanning each eye in 2 to 4 minutes,” he says. “Test validity is the obvious benefit here. Machines only correct for so much movement, tilt, and angle. If patients start to ‘wilt’ at the machine, validity goes down fast. Studies show that the longer it takes to do the test, the more problems occur. So shorter is always better, as long as it’s comprehensive,” he adds.
Also associated with the RTA 5 is the increased speed of individual scan times. “Each scan ranges from one third of a second to less than half of a second, and the system can do up to 10 scans. The older system did up to 13 smaller scans. Each scan area is now 10° by 20° — twice as large as with the previous model. Broader and faster is a good combination. With the larger scans there are fewer spaces between slit images, so the pathology has to be smaller than 0.7° for it to slip through the RTA 5 grid, which we call the ‘pathology net.’ It’s a vertical grid pattern created by each of the slits or cross-sections through the retina, and it’s the tightest parallel sectioning in the industry,” says Crocetta (Figure 3).
Dr. Kahanowicz’s observations of improved ergonomics and user friendliness are on the money, as well, according to Crocetta. “The new system has a completely new optical head design. There is no longer a chin rest, so any tremor that translates through the mandible is eliminated completely. There is free communication without moving the pupil, so it’s faster for the patient, faster for the operator,
and much more comfortable. Additionally, because the patient’s forehead is up against a pad system, there’s no space between the camera and the area where there used to be a chin rest, so light artifacts, which can really plague all optical systems, are minimized tremendously,” he explains.
The RTA 5 has benefits in comparison to other retinal imaging systems on the market as well. “First,” says Crocetta, “is that the fundus image is not just created for stand-alone benefit; it is the foundation upon which all of the quantitative data that we harvest are integrated to. The physician always has complete orientation of where any pathology marker is on the real fundus image. They always know exactly where their orientation is through quantitative data — in any part of the retina and not just at the nerve head like some,” he explains. Another distinction is found in the RTA 5’s slits. “This is the only system that shows not computer generated but real SLO vertical slit images through the full thickness retina,” he says. “In a standard test, the system actually provides a minimum of 88 slits. That’s why pathology has to be smaller than 0.7° to get through the slit formation. The amount of interpolation that we do between any 2 data points is never more than 0.7°, whereas in certain optical coherence tomography (OCT) models, it’s 30°. The RTA 5 is essentially the net that catches the minnows,” he says.
A BROADER VIEW OF THE RETINA The RTA 5
also distinguishes itself with its dynamic 3- D anatomy imaging, which facilitates a full volume view, extracted from any specific scan area of the retina and disc. The elevated 3-D image changes as the operator scrolls through each slit view reflecting anatomic information corresponding with the fundus image. (Figure 4). Ophthalmologist Edward R. Thomas,MD, FACS, of Dayton, Ohio, explains that this interactive feature enables free movement and assessment across the entire grid pattern of the scanned retina along 3 axes options.
Additionally, he points out, technicians can pan, rotate, zoom, and slice the 3-D view for a perspective unlike that provided by any other system.
Dr. Thomas notes that retinal disease is most apparent in 3-D perspectives of the optic nerve head and surface contours of the macula, which highlights another of the RTA 5’s benefits: the system enables 360° rotations of high-resolution 3-D thickness maps for precise assessment of retinal nerve fiber layer thinning and optic disc changes. This, Crocetta points out, makes it ideal for detecting early indicators of glaucoma and retinal pathology, as well as following up progress made over time with injectables. “For any of today’s retinal treatments, this is a perfect device because it enables the physician to quickly see the positive changes or the progression of a disease state through the chosen therapies. It picks up changes in both 3-D and 2-D topography imaging and higher levels of quantification,” he adds. Dr. Thomas says he has had technology that allows for high-resolution cross-sectional imaging of retinal structures in the eye in his office for 6 to 8 years, but this new system is a quantum leap in retinal scanning technology. “Significant updates and upgrades of this technology have been taking place since the first generation of the RTA. Now with the RTA 5 we have ultra-high-resolution capabilities that allow for more sophisticated diagnostics as well as advanced treatment possibilities,” says Dr. Thomas. “In the past 6 months we have seen a revolution in retinal imaging technology comparable to the original computers vs today’s sophisticated computers. These ultra-high-resolution scanners allow for a much clearer view of the retinal layers, with excellent image quality and decreased acquisition time,” he adds.
In addition to, or perhaps more accurately because of, the RTA 5’s diverse capabilities, broad reimbursement benefits are associated with the system. “Because the RTA 5 visualizes the full posterior pole — as opposed to just the optic nerve head or just the macula — and because it is also a fundus imaging system and a SLO system, reimbursement is available through CPT 92250 (photography) or CPT 92135 (pathology scanning),” explains Crocetta. “This system affords tremendous flexibility with respect to reimbursement — through either code,” he adds. For instance, it is common knowledge among retinal specialists that reimbursement for following dry age-related macular degeneration (AMD) can be challenging because a practice cannot technically get reimbursed for SLO imaging for dry AMD, but because the RTA 5 has a fundus system, hypothetically, the practice can bill under the fundus code.
Another reimbursement benefit is found in the system’s vision wellness exam. This vision-loss–prevention screening program takes just 2 to 3 minutes and does not require a dilated pupil. It acts as an excellent patient education tool and establishes a performance baseline upon which future checkups can be compared. “Ophthalmologists charge from $25 to $40 for this out-of-pocket pay procedure. This represents an additional return-on-investment opportunity for the practice that opts for this versatile technology. Perhaps most importantly, the vision wellness exam profiles any practice as a true leader in the global initiative to prevent blindness,” says Crocetta.
Retinal Physician, Issue: March 2007