Nonmydriatic Cameras in Retinal Practice
Five cameras for the posterior segment.
ANDREW E. MATHIS, PhD, MEDICAL EDITOR
Nonmydriatic cameras, which examine the fundus without dilating the pupil, provide rapid results for ophthalmologists interested in diagnosing retinal disease, thanks to the absence of excess light entering the eye and thus less interference with accurate rendering of the interior of the eye. Because of their efficacy, many of the companies that specialize in ophthalmic imaging have introduced nonmydriatic cameras over the past several years. Retinal Physician spoke with several specialists about 5 popular nonmydriatic cameras currently on the market.
Canon (Irvine, CA) has 2 key promotional points for the CR-DGi nonmydriatic camera: speed of results and user-friendliness. With a personal computer attached to the camera, Canon says in its brochure, ocular conditions can be checked immediately. Canon is also highlighting the reduced illumination needed for imaging with the CR-DGi, which it says is 90% less than with instant photography and 75% less than with film photography.
Ben Szirth, PhD, director of the Applied Vision Research Laboratory at the Institute of Ophthalmology and Visual Science at the University of Medicine and Dentistry of New Jersey in Newark and a specialist in the early detection of vision-threatening diseases (VTDs), uses the Canon CR-DGi in community-based screenings as part of outreach and state-funded programs.
Dr. Szirth says, "We screen individuals (no need to dilate their pupils with this type of camera) for VTDs, age-related macular degeneration, cataracts, diabetic retinopathy, and glaucoma. In our Outreach Community screenings, we have had a 14% pick-up rate for some form of VTD. Some of these will be followed by ODs in the management, while a smaller percentage will be for actual treatment (after full clinical evaluation)."
Asked about the CR-DGi's versatility, Dr. Szirth says, "It is very useful in its ability of screening through small pupils. Furthermore, the Canon CR-DGi has very high-quality optics and produces images with high definition and detail that could be missed when performing a routine clinical binocular indirect ophthalmoscope."
"In the best of all worlds," Dr. Szirth says, "we would like to have a retinal camera that could capture images that require even a smaller pupilary dilation (under 2 mm), but such a system is not currently available for traditional nonmydriatic retinal cameras."
Ease of use is also by noted Dr. Szirth. He comments, "Our image-capture screeners are trained using precise techniques that allow for consistency in field of capture and use in small-pupil size. The training can be accomplished in under 2 hours, and follow-up is provided for about 1 week with periodic image-quality review."
CARL ZEISS MEDITEC VISUCAM PRO NM
Carl Zeiss Meditech (CZM; Dublin, CA) introduced the Visucam Pro NM some time ago, but it has added another device to its armamentarium: a "two-in-one fundus camera system," the Visucam NM/FA. This camera has FA ability as well as the standard features of a nonmydriatic camera, including a small-pupil mode, enabling retinal physicians to take fundus images of pupils as small as 3.3 mm without dilating the pupil.
Carl Zeiss Meditec's VISUCAM Pro NM
William Cosman, MD, an ophthalmologist with Lake Plains Eye Center in Medina, NY, has had the Visucam NM/FA for only 1 month, but he is already impressed with the all-in-one device's versatility.
Dr. Cosman says, "We are a general practice with a wide variety of pathology, from serpiginous choroiditis to routine age-related macular degeneration and diabetes. The FA capabilities are very useful for a wide variety of pathology.
"I am suprised at the quality of the fluorescein images especially," Dr. Cosman continues. "They are quite good."
Dr. Cosman is also impressed with the ease of use of the Visucam NM/FA. The camera is "extremely intuitive and easy to use," he says. "It is by the far the best feature of the camera. All 7 of our technicians can now take quality photographs with a very short learning process."
Dr. Cosman says that while photos of the periphery are limited (CZM is quick to point out that if the pupil is dilated, the Visucam NM/FA is capable of near-equator imaging), he is genuinely pleased with the Visucam NM/FA after a short period of use.
KOWA NONMYD a-D 5MEGA
The Nonmyd a-D 5Mega by Kowa Optimed Inc. (Torrance, CA) is marketed primarily based on the clarity of the optics and the speed at which it can be used. It is the only camera on the market to offer both a 45° and 20° field of view. The 20° is used for stereo disc photography, which is easily achieved with the Kowa system.
Among the features that the a-D 5Mega offers are stereo imaging, optic nerve head alignment, a 5-megapixel internal digital camera, a 5.6-inch built-in liquid crystal display (LCD) monitor, and a power-saving timer function. Since the unit is compact, Kowa claims time can be saved during imaging by eliminating the need to search for switches.
Besides the hardware, Kowa says its digital imaging software, called VK-2, can interface easily with the a-D 5Mega and be integrated into most practices' pre-existing imaging software. The software allows for on-screen stereo viewing, multivideo input, and networking for interoffice or telemedicine purposes.
Carl J. May Jr., MD, an ophthalmic surgeon in practice in Hanover, PA, says he uses the camera "to document all retinal disease." He comments on the 7.5-megabyte uncompressed images the camera produces: "If the visual pathway is clear and the pupil is big, the quality is very good." The system has a built-in mode to compensate for patients with insufficient pupillary dilation.
Kowa's Nonmyd a-D 5Mega
Generally, the a-D 5Mega has worked out well in Dr. May's practice. The camera is so easy to operate, Dr. May says, that the technicians are able to use it. Indeed, Kowa promotes the camera by stating that it can be used as easily as an autorefractor. The cost-benefit aspect has also worked out well for Dr. May. "The camera quickly paid for itself by taking photos on about 10 patients a day," he states.
Nidek (Fremont, CA) has most recently introduced the AFC-210 nonmydriatic camera. The key strength that Nidek is promoting with the AFC (which stands for "Auto Fundus Camera") is what it calls "stress-free photograph management." The camera, its literature states, is always in focus, provides quality-control photography, and is patient-friendly. While many of the available nonmydriatic cameras are marketed based on user-friendliness, Nidek is 1 of the few companies to stress patient comfort in its product literature.
Nidek is also stressing the compactness of the unit, as well as a feature not seen on other nonmydriatic cameras: automatic blink detection. If the patient blinks while undergoing the imaging process, the AFC-210 will stop taking photographs until the eye is open again.
Jaime Jiménez, MD, a retinal surgeon who serves as vice president of Southern Eye Center in Hattiesburg, MS, uses the AFC-210 in his practice, and has generally found it to be a good fit, using it for documentation of retinal pathology prior to cataract surgery.
"The Nidek camera is very versatile," Dr. Jiménez says. "It is compact enough to roll from room to room to accommodate our patients. The hardware and software are very user-friendly. It has excellent photo montage software."
"The camera produces high-quality images, but not as sharp as with dilated pupils," he stipulates. "The non-mydriatic component of the camera makes it very time efficient," he notes, however. Dr. Jiménez also notes that the AMC-210 does not allow for red-free photography or fluorescein angiography (FA), though neither do many other nonmydriatic cameras.
Dr. Jiménez is impressed with the storage capacity of the AFC-210. "There is enough storage for 300 to 400 gigabytes," he says. "Since each photo is compressed to 1 megabyte, there should be enough memory for about 300000 photos."
Topcon's (Paramus, NJ) TRC-NW6S non-mydriatic camera is marketed specifically for retinal imaging. However, the ability to image the anterior segment is also available, as the product brochure points out.
The TRC-NW6S is the centerpiece of what Topcon calls its "total imaging solution," which also includes the latest closed-circuit device (CCD) camera technology and Topcon's trademarked IMAGEnet Lite System and AutoMosaic imaging software. Topcon is also promoting a new ergonomic design with the TRC-NW6S as a key selling point. All the components of the viewing and imaging systems are now in direct alignment, causing less bodily stress for the imaging technician, as well as providing a more compact design.
Among the physicians using the TRC-NW6S is David Liebergall, MD, FACS, who is in private practice in Suffern, NY. "We are using the camera to photograph any retinal pathology we see in the office," Dr. Liebergall says, "including choroidal nevi, retinal vascular disorders such as vein occlusions, arterial occlusions, following diabetic retinopathy, and optic nerve disorders."
Dr. Liebergall continues, "The camera has been shown to be an excellent tool for providing outstanding digital images of the pathology, and the patients are now able to visualize on the monitor what I see in their retina and how it caused their visual problem."
Ease of use is another feature of the TRC-NW6S that Dr. Liebergall points out. "Our technicians usually take the photographs and only require a 5-minute training course to get comfortable using the camera. The patient positioning and centering is easy," he says. Similarly, image quality, Dr. Liebergall says, is excellent. "And while on the monitor," Dr. Liebergall continues, "the images are easily magnified and adjustable for teaching purposes."
The only limitation with any non-mydriatic camera that Dr. Liebergall points out is pupillary. "Even though a camera is non-mydriatic," Dr. Liebergall says, "patients with smaller pupils still will need to be dilated." Cost-benefit analysis has not been an issue. "It paid for itself within the first 6 months of use," Dr. Liebergall said of the TRC-NW6S.
Clearly there are a multitude of choices of nonmydriatic cameras available for the retinal specialist. Every practice should consider its patient base, case load, and which features of the several nonmydriatic cameras available are the most essential to optimizing the eye care they provide when deciding which camera to purchase. RP