Coming of Age With OCT

Just in time, this instrument has matured into a full-service technology to help you respond to today's practice squeeze. Here's how to take advantage of its increasing applications.

By Sean McKinney, Contributing Editor

OCT will become increasingly important in the years ahead, providing ophthalmologists with fast, reliable and precise data that will help them see more patients in less time.

"The latest version of OCT is quite remarkable," says Michael Jacobs, MD, owner of Athens Eye Associates of Athens, GA. "We can see so many subtleties in the eye that we couldn't see with the earlier OCT."

Read on to learn why many ophthalmologists believe it to be an essential office-based instrument for maintaining a foothold in the busy years ahead.

What sets SD-OCT apart

The advantage of the newer instruments is that they scan with higher speed, providing precise, layered, 3-D images and extremely high resolution.

For example, the Cirrus HD-OCT (Carl Zeiss Meditec) employs a scanning pattern that totals 27,000 A-scans per second, far superior to the 400 A-scans per second used by the Stratus time domain OCT. For retina, Cirrus offers:

■ A 200 A-scan x 200 B-scan macular cube and optic disc cube that provide a uniform sampling of the 6 mm x 6 mm area of volumetric and area analysis
■ 512 A-scan x 128 B-scan macular cube that offers high resolution in the horizontal cross sections
■ An enhanced HD raster that delivers the highest B-scan image quality for a detailed analysis of the macula.

Besides the Cirrus unit, other types of spectral domain OCT technology include the 3D SDOCT (Bioptigen); 3D OCT-2000 (Topcon); RS-3000 OCT/SLO (Nidek); RTVue (Optovue); SOCT Copernicus HR (Canon/Optopol); Spectralis OCT (Heidelberg Engineering) and Spectral OCT/SLO (Opko).

Positioning My Comprehensive Practice for the Future By J. Isaac Barthelow, MD Spectral-domain (SD) OCT helps me respond to aging patients, decreasing reimbursements and increasing practice costs, while also treating more patients. In the past, I sent many patients to subspecialists for diagnosis and treatment of diseases, such as post-operative CME and wet AMD. Now, instead of losing these patients, I can diagnose these conditions, treat them and handle follow-up in our office, providing injectable therapy when indicated. This approach saves patients a 3-to-4-hour visit to the specialist. I also find OCT to be invaluable in screening patients for premium intraocular implant surgery, looking for signs of macular degeneration, glaucoma, subtle epiretinal membranes and drusen that can sometimes be missed on a slit-lamp exam through a patient's cataracts. Scans from my SD-OCT instrument, the Cirrus HD-OCT, provide patient education, especially when using image review software, such as FORUM. Advances in SD-OCT will improve algorithms, allowing us to manipulate large amounts of data and improving our ability to understand the pathophysiology of disease, rapidly diagnose conditions, provide targeted treatments and monitor disease progression and responses to therapy. Current reimbursements make the purchase of this equipment feasible for most ophthalmologists. The scans are fast and accurate and don't require much technical expertise. Technicians can provide quality scans after an afternoon of training. SD-OCT can help you retain and better meet the needs of every type of patient.     Dr. Barthelow is a comprehensive ophthalmologist from Chico, Calif.

Enhancing retinal care

The number of U.S. citizens who will develop AMD is expected to increase by 50% to 2.9 million between 2002 and 2020, according to a study sponsored by the National Eye Institute.¹ Using the current prevalence of diabetes mellitus in the United States, about 6 million patients will have diabetic retinopathy and about 1.34 million will develop vision-threatening diabetic retinopathy by 2020 — an approximate increase of 32% in both categories.²

Dr. Jacobs says OCT will help him detect these conditions more readily, allowing him to refer challenging cases to retinal specialists. "It helps if I'm able to meet more of my patients' needs," he says.

Glaucoma check

With the aging of the patient population, the incidence of glaucoma will also increase significantly. Primary openangle glaucoma alone affects an estimated 2.22 million people in the United States, and that number will increase to 3.3 million in 2020 as the population ages.³ Rick Lewis, MD, says OCT will be an efficient tool for evaluating suspects, helping with diagnoses, monitoring and determining when procedures are indicated.

"OCT is a great screening tool," says Dr. Lewis, a private practitioner in Sacramento, Calif. "It will be ideal for screening for retinal disease while also checking on glaucoma."

Even though the technology is more sophisticated, today's OCT is actually easily incorporated into testing lanes. Iqbal "Ike" K. Ahmed, MD, FRCSC, assistant professor of ophthalmology at the University of Toronto and clinical assistant professor at the University of Utah in Salt Lake City, says Cirrus HD-OCT offers these benefits:

■ A 6 mm x 6 mm cube of high resolution imaging, allowing optic disc, RNFL and macular assessments
■ Excellent repeatability and reproducibility^4,5
■ Serial exams precisely registered for detection of changes in RNFL thickness.

Avoiding errors

"With Cirrus HD-OCT, the automated registration and ease of use go hand in hand," he says. "Technicians don't have to place the circle exactly where they want it to be around the disc, avoiding a source of error."

Until the Cirrus HD-OCT became available, Dr. Ahmed says that physicians monitoring glaucoma patients couldn't use RNFL analysis to consistently assess progression. With the GPA analysis, however, detection of both localized and generalized changes on up to eight registered images is possible. The RNFL thickness map progression is able to pinpoint changes in focal defects, while the RNFL thickness profile detects change in more shallow or broad defects. The average RNFL thickness progression identifies more diffuse changes. The software also displays an over-all assessment of possible or probable RNFL loss.

Expanding uses for the anterior segment

Anterior segment imaging using Cirrus HD-OCT is made possible with a second built-in lens which works by simply adjusting the imaging focus on the anterior segment structures. SD-OCT has been assigned a category III CPT code, 0187T, as a non-contact diagnostic test for cross-sectional and 3-D imaging of the cornea and the anterior segment. It will be used increasingly to assist in preoperative evaluation and postoperative care. OCT also will be used more frequently to recognize irregularities in the cornea and iris. Practitioners are now using the SD-OCT to analyze anterior chamber angles due to the superior image quality and capability to identify structures not seen with other imaging modalities.

Cirrus HD-OCT allowed effective visualization of this macular hole OD preoperatively and 1 month after it was surgically repaired. Side-by-side analysis was possible using the Viewer module of FORUM.

Harvey A. Fishman, MD, PhD, who provides equal amounts of cataract surgery, glaucoma care and comprehensive ophthalmology services in Santa Cruz and Palo Alto, Calif., says he likes that he can switch from posterior to anterior segment exams while the patient remains in the chair. He also can delegate OCT testing easily to a technician because the unit is small, fast and easy to use.

"I find the OCT invaluable for efficient patient education, so I can explain, for example, why we might do a laser peripheral iridotomy," he says. "The OCT is also a great practice builder. Doctors refer a rich variety of cases to me for consultations."

In the same way, Edward J. Holland, MD, director of corneal services at the Cincinnati Eye Institute, uses the OCT for assessing both the retinal condition and the anterior segment of his patients. "OCT is being used more for premium IOLs. For multifocal IOLs, for example, you need to confirm that the retina is in good condition as part of your pre-operative work-up. If the patient has a significant cataract and you can't see the retina well. That's not good. The patient could have an epiretinal membrane, which if not detected prior to surgery could negatively affect the visual outcome."

How SD-OCT Has Revolutionized My Retinal Practice By Vincent R. Vann, MD, PhD I'm a solo retinal specialist who's not afraid to face the future. I've just opened a state-of-the-art Macintosh-based electronic office in a new medical tower building, where I expect to see more than 6,000 patients this year. I'll do approximately 400 laser treatments and 700 intravitreal injections. I'll perform 250 vitreoretinal surgical procedures, half of them at a hospital and half at an ambulatory surgery center. We'll grow to meet the challenges of increasing disease without abandoning the simple mission statement above our door: "We take the time to care." What is our secret strategy? OCT. At least, OCT is a major part of it. Our Cirrus HD-OCT, connected to a networked ophthalmic image management system, FORUM, allows me to breeze through my schedule while increasing the meaningful time I spend with each patient. Not too long ago, I preferred fluorescein angiography over OCT, trusting the use of early-generation, light-based scanning technology only as a reinforcing test. Now, because of the 3-D precision of SD-OCT, this technology has supplanted angiography. Last year, we performed 1,573 OCT scans, many of them bilateral, compared to 760 angiograms. An angiogram raises the risk of allergic reactions, doesn't effectively penetrate a cataract, and ties up the patient and a staff person for 20 to 30 minutes. I only use the test when I absolutely need to visualize retinal vasculature. Virtually every other diagnostic or follow-up procedure in my office involves an OCT scan, which only takes only a minute to perform. We can do an OCT before patients are fully dilated — and well before I see them in the chair. OCT helps me confirm my diagnosis, assures me that I'm following the right treatment plan, and documents that the patient is responding to treatment. With this device, I see things that would be otherwise impossible for me to see, even though I have 20/15 vision. I'm amazed by what it helps me accomplish in streamlining my practice and improving patient care.     Dr. Vann is owner of RGV Retina Specialists, P.A. of Edinburg, Texas.

Future growth

E. Randy Craven, MD, a glaucoma specialist from Denver, predicts that the evolution of SD-OCT will result in a better correlation of structure, function and hopefully, genetics. In today's busy practices, the result will be improved and more efficient patient care. "You will need to change your approach to testing and observation of basic problems," he says. "For example, data review can be made more efficient by delegating basic testing to other heathcare providers, such as optometrists."

With its speed and versatility, Dr. Lewis also believes that SD-OCT will be critical to mainstream ophthalmology practices going forward. He concludes that "ist is needed to improve efficiency and quality of care." OM

References

1. Friedman DS, O'Colmain BJ, Muñoz B, et al. Eye Diseases Prevalence Research Group. Prevalence of age-related macular degeneration in the United States. Arch Ophthalmol. 2004;122:564-72.
2. American Academy of Ophthalmology Retina/Vitreous Panel: Diabetic Retinopathy. Preferred Practice Patterns. AAO. San Francisco. September 2008.
3. American Academy of Ophthalmology Glaucoma Panel: Primary Open-Angle Glaucoma Suspect Preferred Practice Patterns. AAO. San Francisco. September, 2005.
4. Savini G. Repeatability of Optic Nerve Head Parameters Measured by Cirrus HDOCT in Healthy Subjects. ARVO Poster A589, 2010.
5. Vizzeri G, et al. Agreement between spectral-domain and time domain OCT for measuring RNFL thickness. Br J Ophthalmol. 2009;93;775-781.