Spotlight ON TECHNOLOGY & TECHNIQUE

Cirrus: Not Just Another Pretty Picture

By Leslie Goldberg, Associate Editor

The Cirrus HD-OCT (Carl Zeiss Meditec, Dublin, Calif.) offers proprietary high-definition optics for superior visualization of anatomical details across a wide range of patients. The system's resulting images, 3-D layer maps, fundus images and quantitative analyses reveal clinically relevant details that improve detection and monitoring of retinal conditions such as age-related macular degeneration (AMD) and glaucoma.

Thomas Hanscom, M.D., in private practice in Santa Monica, Calif., is a Cirrus user and receives many patient references as a retinal physician. He acknowledges that one of the reasons for caution some would-be users have about the new technology is — while the Cirrus and the other-spectral domain OCTs deliver phenomenal pictures with high resolution — is that all they deliver?

"People in my neighborhood are holding off purchasing spectral domain OCTs because of this question," says Dr. Hanscom. "Are they really adding to the bottom line of diagnosis, therapy and flow in the office?" Below he provides several reasons for considering adding the Cirrus to your armamentarium.

Patient and User Feedback

"The one area where there is absolute superiority," says Dr. Hanscom, "is patient and operator experience. Technicians say that there is a 90% more ‘wow’ factor by the patient. The patient says the experience is fantastic. It's easier, it's more comfortable — the ergonomics of where the chin rest is makes it more comfortable and it's a shorter chair time."

Dr. Hanscom estimates that operators spend 8 minutes on two eyes with the Stratus and 3 minutes on two eyes with the Cirrus. "It may not seem like a lot, but when you are seeing between 20 and 40 patients on a busy day — and the patients are elderly and uncomfortable — that ends up being a huge difference," says Dr. Hanscom. "It's less than 50% of the chair time by the patient.

"The operator is similarly enthusiastic. The interface is better. It is easier to find the pupil and easier to localize the center on the macula and optic nerve. There are rave reviews from the patient and technician about the experience of acquiring the scan."

Patient Benefits

Dr. Hanscom says that another absolute superiority with the Cirrus is pupil size. Although the literature says that pupil dilation is not required for pupils as small as 2.5 mm, he says that his operators can get really good scans with 2.5 mm pupils and even 2 mm. "Even though as a retina specialist we dilate both pupils most of the time, many of the [ranibizumab] Lucentis [Genentech] and [bevacizumab] Avastin [Genentech] injection-type patients who are coming back frequently are not getting both pupils dilated every time. To get a 2-minute OCT exam of the fellow eye, which is not dilated, is a major benefit."

Dr. Hanscom has found two cases of leakage in the fellow eye that way. "A patient has come in for treatment in one eye and we have scanned the other eye as a screening test, undilated, found something and diagnosed a neovascular membrane.

"Ease of visualization also relates to other optical problems such as cataracts, lens implant with capsular opacity, vitreous opacities, corneal opacities — problems a user would have viewing the fundus. These are not issues with the Cirrus," says Dr. Hanscom. "Since we don't dilate the fellow eye every time and probably would not have attempted viewing the undilated pupil with the Stratus, the leak would not have been detected until months later."

Other Features

Glaucoma. A cube scan captures a 6 mm × 6 mm area for glaucoma analysis. The Auto Centering feature means the center of the cup is identified and a 3.4 mm diameter circle extracted from the cube of data. This provides precise repeatability and reproducibility. Analyses include an RNFL thickness map, RNFL TSNIT analysis, comparison to normative data and OU analysis.

Increased Speed. The Cirrus's high-definition spectral domain technology has faster scanning capabilities, capturing more data and revealing greater detail of retinal tissue and pathology. The Cirrus delivers 27,000 A-scans per second compared to the 400 A-scans per second of time-domain OCTs. This makes the Cirrus less dependent on patient fixation. Additionally, the faster speed means less movement artifact as well as the ability to generate more detailed 3-D images.

Registration. The Cirrus enables repeatable visualization of clinically relevant anatomy with exact correlation between the OCT scan and the fundus image. Visit-to-visit registration with overlay of the fundus image from the previous scan assures reproducibility. A high-quality line scanning ophthalmoscope fundus image and OCT data are captured simultaneously, so clinicians know the exact correlation between any OCT scan and the fundus image. High-definition data acquisition and advanced analysis provide precise registration and excellent reproducibility critical for glaucoma detection and management.

Superior Visualization. Advanced optics also aid in the examination of patients with cataracts. Dilation is not even required for pupils as small as 3 mm. Three-dimensional rendering of macula and optic nerve head provides new ways of visualizing the retina.

The Cirrus HD-OCT is the first device to isolate the retinal pigment epithelial (RPE) and inner limiting membrane (ILM) layers so that even subtle pathology is displayed in greater detail. Clinicians can better detect subfoveal lesions and the exact location of drusen displayed on 3-D RPE layer maps. In addition, users can view ILM layer maps and retinal thickness maps in a high-definition, cross-sectional display.

"With the Cirrus, outpatient care and office flow has been improved," says Dr. Hanscom. "The Cirrus is more than just an instrument that delivers prettier pictures." OM

For more information on the Cirrus, visit the CZM Web site at www.zeiss.com.