Spotlight ON TECHNOLOGY & TECHNIQUE

OCT Offers Tools to Ease Clinical Judgments

By Samantha Stahl, Assistant Editor

The Total Corneal Power functionality on Optovue’s RTVue SD-OCT provides detailed information for increased accuracy in calculating corneal powers.

OCT technology has experienced a rapid evolution in the past few years, bringing consistent upgrades to image quality and extra device features. Optovue’s RTVue SD-OCT system offers glaucoma management and IOL power-calculating capabilities that proponents say can substantially aid clinical decisions.

Total Corneal Power

“Corneal power is the holy grail in ophthalmology,” says Robert Brass, MD, of Latham, New York. He insists the high praise isn’t just talk — especially considering the coming influx of cataract patients, many of whom had LASIK performed years prior. These patients demand perfect vision but, unfortunately, it’s extraordinarily difficult to calculate the correct intraocular lens power to use. That, he says, is where the RTVue’s Total Corneal Power capabilities come into play.

“If you go out and do LASIK and change the anterior segment, our usual formula to accurately calculate lens power is ruined,” Dr. Brass says. Instead, the RTVue measures the length from the front to the back of the cornea — variables you don’t get using standard keratometry. By managing the anterior and posterior curvature of the cornea with OCT, he says that he now has the potential to solve the dilemma that ophthalmologists continually face: predicting the right formula. Where a typical postop LASIK calculator might provide nine different guesses, usually with a full two-diopter range, it is extremely challenging to choose the right IOL power. “The RTVue points me in the right direction,” he says. “I’ve used it with postop LASIK patients and the OCT guides me to a choice that’s correct.”

Ganglion Cell Complex Scan

Timing is everything when it comes to halting glaucoma progression, but spotting the first signs of cell thinning is easier said than done. Optovue worked with OCT co-inventor David Huang, MD, PhD, to develop the first OCT ganglion cell complex (GCC) analysis tool a few years ago.

“The RTVue’s GCC tool gives you quicker, earlier analysis of what’s going on,” says Dr. Brass. While glaucoma diagnosis has always been focused on the optic nerve head cells, he explains that the GCC scan looks at the macular area and identifies the thickness of the GCC. New databases of what constitutes as a “normal” thickness help translate this information into a meaningful signal of progression. “Identifying thinning in that area, in theory, is a much earlier, greater indicator than looking at the optic nerve head,” he says. He uses the scan on patients for whom he has a difficult time predicting whether or not disease will progress.

He says that the Optovue module gives a more sensitive slice of what’s going on and allows physicians to hone in on different indicators. Visual field testing is the gold standard, Dr. Brass says, just because it’s out there — it doesn’t always necessarily identify anything important. Having the ability to detect focal and global loss with the GCC analysis can make a big difference. “It gives you one more piece of the puzzle that may help you offer better treatment down the line.”

Overall, Dr. Brass says the system is an economical, user-friendly way to go with anterior and corneal power modules that attach onto the posterior imaging machine. “It’s really easy to use. It’s error proof — just aim and shoot — and it acquires a lot of data very quickly.”

Despite the technology’s impressive advancements, “OCT is really in its infancy,” he says. While there’s no doubt that the platform has monumental developments in store, the current offerings have the ability to make diagnostic judgments all the more clear. OM

For more information, visit www.optovue.com.