Refractive surgery: Advanced optical coherence tomography an integral diagnostic tool

June 15, 2009

Advanced optical coherence tomography (OCT) devices used in routine screening of refractive surgery candidates can enable clinicians to obtain better results or determine if there is a reason the surgery should not take place. Advanced OCT imaging can reveal anatomic features missed by other screening instruments.

Key Points

"We perform posterior-segment OCT on all patients being evaluated for corneal laser or IOL refractive surgery," he said. "We also have included it in our biannual follow-up exams of previous refractive surgery patients. I am getting to the point that I would not suggest elective refractive surgery without this valuable tool. Just like topography and pachymetry, it helps me decide who is a candidate and educate patients regarding their potential outcome[s]. It's the best way I know to make sure there is good film in the camera before I try to improve the optics."

Cases

Similarly, preoperative screening in another patient revealed a congenital macular cyst that could not have been seen during a fundus exam or a magnified macular exam. Although the cyst did not interfere with correction of the patient's myopia, the discovery was beneficial.

"We could have been searching for a long time for the reason her best-corrected vision was not quite 20/20, and I could have been wondering whether she had higher-order aberrations or something was going on with her lens or cornea," Dr. Durrie said.

Knowing that she had congenital functional abnormalities in her retina helped clinicians predict the potential surgical outcome and also exposed the reason that perfect 20/20 vision had never been achieved in the patient with glasses or contact lenses.

In another case, OCT screening in a patient who had undergone LASIK several years earlier identified optic nerve edema and led to the diagnosis of a baseball-sized frontal lobe tumor. The neurosurgeon involved in the case commented that he had seen a tumor this size that was found before there were symptoms such as bleeding or a stroke, according to Dr. Durrie, and the early detection played a part in the excellent outcome that was seen after surgical removal.

He also mentioned that the views of retinal anatomy that are possible with SD-OCT are valuable educational tools for his staff as well as for patients.

"It's really good diagnostic information, it's good education for the patient, and it's good medicine," Dr. Durrie said. "A lot of people think it's overkill and don't want to buy a $60,000 machine they don't have to have. But I think that when people are going to choose elective surgery and pay $4,000 or $9,000 for it, they expect us to do the testing that is necessary to make sure they're a good candidate."

He also observed that use of advanced OCT for refractive screening seems to be a budding trend. He said he increasingly encounters colleagues who say they use OCT for this purpose or are considering it. Many clinicians already have OCT devices in their office but only use them when the test can be billed to a private insurance company or Medicare.

"In the refractive surgery part of the practice, they could use it on everybody and build it into the normal cost of the surgery or the work-up," Dr. Durrie said. "Think of it as something we could add to our practice because we think we can get better results."

Various advanced OCT systems can be used to screen refractive surgery patients. Dr. Durrie's instrument of choice has an SD-OCT and a built-in fundus camera, the findings of which can be correlated to the retinal image. With one device capable of performing two tests, he replaced the separate fundus photography unit he had been using for routine digital fundus imaging, he concluded.

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