instrumental strategies

We Can Be Heroes

Instrument aids in your ability to prevent vision loss.

JAMES L. FANELLI, O.D. AND ROBERT W. DUNPHY, O.D.

In anticipation of season three of "Heroes," a recent Global Television poll asked 1,000 Canadians what superpower they'd want. The top two answers: the power to heal (45%) and time travel (25%). Arguably, these are the most coveted super powers of all medical professionals. We hate to see our patients suffer, and we often wish we could go back in time before their diseases became full blown to prevent current suffering.

Although technology doesn't offer either one of these superpowers, it does offer a device that enables you to identify posterior segment disease in its earliest stages — curbing that medical-related wish to time travel. It's called the HRT 3, from Heidelberg Engineering.

The full picture

The device, which is a confocal scanning laser ophthalmoscope, employs a laser light that obtains three sets of sequential images (64) of the retina or optic nerve in 24 milliseconds. Each retinal scan is 384 × 384 pixels, or 147,456 data points covering 15° of the retina. Image redundancy ensures that the data collection and processing are accurate enough to provide true representations of the retina/optic nerve that don't contain artificially interpolated data. (Because this image acquisition is faster than most voluntary and involuntary eye movements, motion artifact often isn't an issue.)

Next, the instrument's TruTrack software discards any low-quality images. Then, TruTrack uses anatomical features, such as blood vessel patterns, among other characteristics, to provide you with a 3-D model of the retina. The software assesses this 3-D model for signs of disease by evaluating the images for light scatter — an indication of retinal edema. You can then view or print the images from a computer that comes with the device.

When the patient presents for subsequent exams, TruTrack provides you and/or your technician with a grid of the area of the retina from which it acquired the images for the first exam. This is important, as it helps in overlapping as much data as is possible from baseline images. Also, the software reveals statistical differences among exams to account for within-exam variability.

Heidelberg's HRT 3 HEIGHT: 18.5 inches WIDTH: 9 inches LENGTH: 11 inches WEIGHT: 26 lbs.

The HRT Retina Module (a separate software component) has allowed us to effectively diagnose and monitor patients who have diabetic retinopathy and vein occlusions, among other retinal pathology. It includes an Edema Index map, which identifies suspicious areas of the retina (i.e. changes induced by minimal accumulation of fluid) that you may not see via contact lens examination. Often, the Edema Index highlights areas at risk that, for example, might not meet the definition of clinically significant macular edema, yet do show signs of early edema. You can then use subsequent exams to concentrate on that same exact area of the retina with the assistance of the TruTrack system.

The Module's Retinal Thickness feature acquires retinal thickness measurements to create a complete 3-D map of the scanned area without interpolating data. This, in turn, provides you with a clear idea of the patient's retinal anatomy. The scan tells you whether the patient has retinal thickening, how much, and on subsequent exams, you can assess whether it's increasing or decreasing.

The Edema Map component takes the information from the Reflectance Image, which captures differences in the retina's surface appearance, and Retinal Thickness component and analyzes the reflectance and scatter properties of retinal tissue to pinpoint spatial differences in tissue hydration — a key factor in deciding how, specifically, to intervene.

Patient care

Implementing the HRT 3 in our practices has had a profound impact on patient care. In glaucoma cases, it's enabled us to improve our diagnostic accuracy of abnormally classified nerve heads and has guided our management protocol, as optic nerve imaging enables us to verify neuropathic stability and functionality through time. Also, we can now compare glaucoma patients via age and race norms through the device's Moorfields regression analysis component. Age-related macular degeneration patients have benefited from the HRT 3, as the device has enhanced our ability to detect neovascular membranes, facilitating our disease-management decisions.

In addition, we've noticed that the ability to provide our patients with a true depiction of their disease has improved compliance to our prescribed treatments and follow-up visits.

Financial incentive

When considering investing in any instrument, you must acknowledge not only advances in patient care delivery, but also the ability of the instrument to produce a return on your investment. In our experience as private-practice owners, we've seen a more significant return on our investment than we originally anticipated. For example, my (Dr. Fanelli's) initial pro forma actually underestimated the number of procedures we'd perform, as the device generated more than 1200 scans last year.

Because the HRT 3 enables you to identify the early presence of posterior segment disease and monitor its progression, you have the ability to prescribe the most appropriate and timely treatment to stave off vision loss. This makes you a superhero to your posterior segment disease patients. OM