DIAGNOSTICS

Detect Retinal Disease Early

You may prevent vision loss with the help of this three-in-one device.

John Warren, O.D., Racine, Wis., Thomas P. Kislan, O.D., Stroudsburg, Pa. and Janet M. Mint, O.D., Jacksonville, Fla.

The early detection of retinal diseases, such as diabetic retinopathy, glaucoma and age-related macular degeneration (AMD) lead to timely treatments, which can prevent and retard vision loss. For this reason, it's essential we utilize retinal imaging devices that provide us with the fullest field- and depth-of-view. Utilizing such devices not only ensures the best care for our patients but also enables us to retain and attract patients, as they know we are up-to-date on the latest developments in eye care.

Here, we discuss why we employ the Retinal Thickness Analyzer RTA 5 — a diagnostic device that includes digital fundus imaging, posterior pole scanning, optic nerve head structural analysis and retinal nerve fiber layer (RNFL) thickness analysis — from Marco.

Myriad features

The RTA 5 offers six features that have enabled us to identify retinal pathology, while providing patient and staff comfort:

1. Fundus image quality.
The device has up to a 9.4 megapixel resolution, providing quality images, and up to 72 × 60° fundus views compared with the 1.7 to 3.4 megapixel resolution of the RTA 4.
This improvement in resolution is significant. The digital photo serves as a foundation, upon which the devices 2-D retinal thickness and normative deviation maps are built. In other words, you can view and identify retinal markers and pathology with the RTA 5.





The Dynamic 3D Anatomy Imager provides 3-directional sectioning through the macula and perimacula scan volumes. This macular hole shows clear compression of the RNFL and RPE, directly above the fundus image marker.
2. Scanning without dilation.
The RTA 5 provides a dense array of scanning laser ophthalmoscopy (SLO) grid patterns via full peripapillary and perimacular fields often without the need for dilation. This is because the device only requires pupils be at least 3mm to obtain accurate readings.
The device's predecessor, the RTA 4, required a minimum 4.25mm pupil size to obtain accurate readings, making dilation a requirement. Patients appreciate avoiding the light-sensitivity, inability to focus and interruption of their daily activities associated with dilation.
3. Large-area macular scans in a short time.
The macular scans cover a larger area in one-half the time of the scans of the RTA 4.
In the RTA 4 series, all scans were 3 × 3mm, and a complete analysis consisted of 13 individual scans. By minimizing overall test time, it is possible to add the peripapillary scans in a reasonable timeframe, or complete the basic scanning process in a significantly shorter amount of time than with the previous platform device. While the optic nerve and peripapillary scans are 3 × 3mm, the macular scans are 3 × 6mm. This means the RTA 5 provides larger scan areas with more condensed grid patterns (separated by 0.7°) in shorter times.
A complete 40 × 60° analysis, including the full 20 × 20° peripapillary area, consists of six individual scans as opposed to the 13 of the RTA 4. It is also able to perform a complete six-scan analysis in a shorter amount of time than the basic analysis with the earlier series.
You can add an additional four user-defined, 10 × 10° scans to the basic four-scan exam, or to the expanded six-scan peripapillary exam. Note that you can overlay any of the RTA 5 SLO patterns onto either a 40 × 60° or a 60 × 72° fundus image.
Also, the speed with which the device operates allows us (staff included) to utilize our time more efficiently. It has enabled us to spend more time discussing diagnosis and care with our patients — something we feel has improved both follow-up appointment-show rate and treatment compliance.
Further, our patients have commented on their ability to "get more accomplished" during the day, due to the speed of the exam and the diminished need for dilation.

4. Easy screen transition commands.
The RTA 5 features icon-menu selections and more intuitive screen-transition commands than the RTA 4. Marco has automated the previous RTA 4 manual adjustments and better integrated quantitative and qualitative reporting on the RTA 5, to layer 2-D and 3-D maps onto the foundational fundus image — with clear retinal markers.
5. "Anatomy Imager" program.
This feature allows us to lift a volume of the retina (that exactly coincides with any selected scan area) and dynamically section through this volume in three axes — including retinal pigment epithelium (RPE)-to-RNFL slices.





This 2-D numeric retinal thickness map overlays the fundus image at specified retinal markers. Results show an overall depressed field with significant thinning quantified in inferior perimacular and peripapillary regions.
The ability to see the tissue from many angles greatly enhances the clinical picture, especially when evaluating the optic nerve and the macula in diabetic patients and when visualizing neovascular- and drusen-related RPE elevations and separations in AMD patients. Due to the densely packed data, the device is able to pick up small areas of thinning and thickening, which minimizes false interpolation and maximizes real data.
This interactive program provides us with perspectives on pathology that we can measure, record and save as transferable files for professional consults.
6. Ergonomic design.
The instrument's optical-head design, which is outfitted with pads for the patient's forehead and cheeks, does not utilize a chin rest and has a natural, slightly downward posture, providing the patient with a more comfortable head position and a more tolerable target light intensity, than the RTA 4.
The RTA 4's optical head design allowed for some patient movement through the mandible and a scattering of ambient light through the optical pathway — both of which can cause false positive data.
Due to the ergonomic design and intuitive scanning sessions, staff is able to work more efficiently. For instance, capturing the pupil is facilitated with an added space-bar firing method.
Perhaps the least measurable, but most notable feature is the patient response to the bells and whistles of this device. For instance, we use the device's remote viewer software as well as its 3-D photos and maps (that can be rotated 360°) to provide an intuitive depiction of the test results for our patients. This enables us to strengthen patient education regarding diagnosis and care, as viewable evidence of one's pathology increases the seriousness of the issue in the patient's mind. This makes the patient more likely to comply with follow-up visits and the prescribed treatment.

Utilization

We mainly employ the RTA 5 on patients who report a positive family history of retinal disease.

Some examples of candidates:

► Glaucoma suspects. This group includes those patients who have a positive family history of glaucoma, cup/disc ratio asymmetry, intraocular pressure (IOP) asymmetry or a change in IOP trend.

For instance, if a patient presents with an (IOP) of 21mm Hg in each eye at his comprehensive eye exam, and his past IOP readings have measured 13mm to 15mm Hg, we can use the RTA 5 to determine whether the increase has caused early macular or retinal nerve-fiber thinning that necessitates treatment.

The 3-D anatomy imager allows interactive scrolling (in 3 axes), through the nerve head. ONH structure shows a large, irregular and pitted cup in this glaucoma patient. This same program can be used at the macula and through all scan volumes.

Ganglion cell damage and nerve fiber layer dropout before visual field loss serve as early indicators of glaucomatous damage. On a complete scan, we can observe ganglion cell loss with the topographical and numerical data.

RNFL thickness is depicted in graphical analysis, and we can easily evaluate superior and inferior nerve-fiber loss. The device also takes a digital optic-nerve image, which we can view in 3-D. We can rotate and view this image at different angles, facilitating our ability to make judgments regarding cupping, sloping and notching.

Further, because the RTA 5 illustrates subtle changes in retinal thickness, it enables us to carefully monitor established glaucoma patients.

► Diabetic patients. This instrument aids in the diagnosis of diabetic retinopathy and cystoid macular edema (CME). In the case of diabetic retinopathy, the device enables us to detect pockets of edema or cystic changes via its slit images or its topographic analysis — changes that may be missed with normal stereoscopic fundus viewing.

These six B-scan slit images depict scan progression through a cyst, with spacing less than 1° between B-scan images. A total of 88 to 200 of these slits and 1408-3200 data points are generated in RTA 5 testing.

Also, it allows us to measure the size of these changes and the distance from the macula, so we can determine whether macular edema is clinically significant. And, we can measure the distance from the macula of any hemorrhages or exudative changes, aiding in the diagnosis of clinically significant CME.

Finally, should a patient undergo retinal laser treatment, we can see and show the patient the post-operative change in retinal thickness.

► AMD suspects. The RTA 5 scans allow us to view the macula and analyze the ganglion cell layer. In AMD's early stages, we can see drusen build-up and elevation changes in the macular region and discern elevation changes due to drusen from possible neovascular changes.

As the dry form of AMD progresses, we tend to see thinning and atrophy on the macular region. We can also visualize these changes with the device's topographical analysis.

Further, horizontal slits can take axial cuts through the macula (or ONH) and allow measurements of any areas of pathology. Since the slits are less than 1° apart and perpendicular and parallel in orientation, only the smallest developments pass through this pathology net. We've saved these cuts on an internal video and sent them via e-mail for consultation purposes.

► Postoperative cataract patients. Many postoperative cataract patients present healing well, but not achieving the desired postoperative visual acuity (VA). By scanning with the RTA 5, we can view the macula and decide whether CME is present and precluding the desired VA. Evaluating the slit-image of the macular region along with topographical evaluation guides us as to whether further treatment, such as a topical steroid, may be necessary.

RETURN ON INVESTMENT

Aside from the increase in staff efficiency and patient convenience we've seen with the RTA 5, we've also been able to increase practice revenue via insurance submission for fundus imaging (92250) and SLO scanning (92135) (under a broad list of qualifier codes).

In many cases, it would be beneficial to gather more patient data during a visit. However, only one of these CPT codes is appropriate to bill for any single visit. Medicare currently pays approximately $44 per eye for code 92135 and $65 for 92250, which is a bilateral code and not billed for each eye separately.

Another application that has enabled us to increase practice revenue: the device's Vision Wellness Exam. This is a four-scan analysis on a non-retinal-disease suspect who presents for a regular exam. The report gives us data on retinal thickness, optic nerve head and fundus photos, though does not compare the data to the normative database or provide the numerical metrics that the full exam does.

We offer this screening for an additional fee (around $30). This test provides both the practitioner and the patient with peace-of-mind regarding retinal health, while establishing an important base-line. Should the results indicate the identification of pathology, a more extensive analysis is warranted. We file this analysis under the 92135 code.

We find that most patients understand the significance and benefit of this test, and many have expressed appreciation that we employ such a device.

Further, we've each witnessed the benefit of this application on non-retinal disease suspects. For instance, in two patients who recently presented for their comprehensive exams, the Vision Wellness Exam revealed retinal thinning, identifying these patients as glaucoma suspects, which indicated further evaluation.

Although the main purpose of the RTA 5 is to aid the practitioner in detecting the early signs of retinal pathology, we've found that the device has been beneficial in that it has also enabled us to:

Dr. Warren is in private practice in Racine, Wis. Contact him by e-mail at jwarrenod@gmail.com.

Dr. Kislan is the medical director of Stroudsburg Eye Specialists, Hazelton Eye Specialists and The Dry Eye Clinic of Northeast Pa. Contact him by e-mail at foreeyes@ptd.net.

Dr. Mint is in private practice in Jacksonville, Fla. Contact her by e-mail at jmint2020@aol.com.