While visualization and integrated technologies in surgical ophthalmic microscopes have evolved over the years, there have also been concerns about the potentially harmful effects of prolonged intense light exposure on ocular structures, in particular, the retina. Recently, three-dimensional high-definition digital surgical visualization systems have become available that offer excellent resolution, image depth, clarity, and color contrast.
Dr. Kimberly Sippel and a colleague prepare tissue for corneal transplantation.
“There are many surgical fields in medicine that are very dependent on visualization, and one of the fields in which the highest intraoperative magnification is required is Ophthalmology. The tissues we operate on, and the spaces we work in, are often microscopic,” says Kimberly C. Sippel, MD, Director of Corneal Transplantation in the Department of Ophthalmology at NewYork-Presbyterian/
However, notes Dr. Sippel, there have been long-held concerns in regard to the risk of light-induced retinal phototoxicity due to prolonged high-intensity light exposure from the ophthalmic microscope during anterior as well as posterior segment surgeries. This has led to a search for technology that would allow for the safe performance of surgery using the lowest possible light intensity levels. The recent availability of 3D high-definition digital surgical visualization systems may have addressed that concern.
Low Light Levels with High Definition
In 3D digital surgical visualization technology, a high dynamic range camera is attached to a traditional analog operating microscope. The images from the camera are sent to a proprietary high-speed image processor and then displayed on an ultra-high-definition 3D flat panel screen and viewed by the surgeon through 3D spectacles. Surgeons may increase magnification while maintaining a wide field of view, as well as use digital filters to customize the view, highlighting particular ocular structures and tissue layers. Engineered with a specific focus on minimizing light exposure to the patient’s eye, the 3D system facilitates surgery using lower light levels. Initially adopted primarily by posterior segment surgeons, the 3D technology is also being explored for use in anterior segment surgery, specifically cataract surgery.
With 3D digital surgical visualization technology, images from a high dynamic range camera are sent to a proprietary high-speed image processor and then displayed on an ultra-high-definition 3D flat panel screen. The image appears blurred as it requires special glasses for optimal viewing.
“Our retina colleagues were the first to adopt this technology for a number of reasons, including the fact that their cases tend to take a longer time than cataract surgery,” says Dr. Sippel. “Nevertheless, we try to complete our cataract surgeries as quickly and safely as possible, and always shield the eye any time we’re not actually operating in order to protect the macula from excessive light exposure. What we found when using the 3D visualization system is that we are able to use a fraction of the illumination of the microscope while still obtaining the same quality view.”
The digital image offers several advantages over the microscope, explains Dr. Sippel. “As a computerized image, it can be manipulated and enhanced in a wide variety of ways. You can change the overall tone and illumination. You can change the coloration to enhance the contrast, for example, does it help to have a green cast or a red cast to the image? You can overlay other data, animate it, stop it, or create a movie. You can change the sensitivity and resolution. And importantly, the images and information can also be transmitted, which has only been possible through the microscope when it is equipped with a camera requiring much more light. The digital camera, like a night vision scope, allows one to view things at very low levels of illumination.”
Dr. Sippel, along with Eric D. Rosenberg, DO, MSc Eng, a former fellow in cornea and refractive surgery at NewYork-Presbyterian/
The investigation focused on 51 consecutive eyes of 35 patients who underwent femtosecond laser-assisted cataract surgery between July 2019 and November 2019 at NewYork-Presbyterian/
- light intensity used
- light exposure time
- intraoperative and/or postoperative complications
- postoperative visual acuities
What differentiates our study from previously published studies is the fact that in the digital group, half the light intensity was used on average, and in some instances, up to four-fold less light than that in the traditional group.
— Dr. Kimberly Sippel
The study findings, which were published in the March 1, 2021, issue of the Journal of Cataract & Refractive Surgery, showed:
- no intraoperative or postoperative complications in either group
- no difference in surgical time between the two groups
- the mean light intensity used in the digital group was significantly less (18.5 percent ± 1.5 percent) than that in the traditional group (43.3 percent ± 3.7 percent)
- the digital group achieved a postoperative day 1 visual acuity within 2 lines of the postoperative month 1 visual acuity a greater percentage of time than that in the traditional group (81.5 percent of eyes versus 54.2 percent of eyes)
“In our published article, we show two intraoperative images using the two visualization platforms at markedly different coaxial light intensities,” says Dr. Sippel. “The traditional view is at 40 percent of the maximum light intensity, while the picture taken with the 3D system is at 10 percent. The two images are comparable indicating that we are able to use a fraction of the light intensity and still achieve the same visualization. That is very significant.”
Dr. Sippel also points to the musculoskeletal benefits to surgeons when performing surgery with 3D digital visualization. “It can be very difficult to be looking through the oculars of a traditional analog microscope for hours on end,” she says. “Orthopedic problems such as chronic cervical spine and neck pain are a huge issue in ophthalmology. So, from an ergonomic standpoint, it is much better and more comfortable to look straight ahead at a flat screen monitor than to be bent over the oculars of a microscope.”
“Analog operating microscopes are great optical instruments, but their evolution is mature,” continues Dr. Sippel. “3D digital surgical visualization is really in its infancy. The ability to enhance an image, to use low levels of illumination, and to facilitate the engagement of the entire operating room group – these are all enormous advantages of the new digital technology. With a microscope view, typically the surgeon and one other person peering through the microscope have a view. The scrub nurse, circulating nurse, and trainees are unable to view what is going on – except perhaps on a 2D screen. With a massive, well-positioned plasma screen offering a 3D view, everyone in the room is immersed in the surgery, permitting improved engagement and a more rapid, coordinated response to situations that may arise. While we are just at the beginning of our journey with 3D digital surgical visualization, this technology represents a key further step in the continued evolution in the visualization needed for our very delicate surgeries.”