Cataract surgery is one of the oldest surgical procedures documented, arguably dating back to ancient Egypt at 1200 B.C., with a tomb painting depicting couching.1
Within the last 300 years, surgical prowess coupled with technology has elevated the procedure into one of the most successful treatments in all medicine.1,2
With each iteration, one can uniquely identify a skill, apparatus, or scientific development that led to the procedure's renaissance, ultimately improving patient safety and outcomes.
The history of visualization tools in ophthalmic surgery
In the late 1850s, surgical loupes were becoming increasingly popular due to their relatively lightweight nature and two- to three-times magnification.3 Around the same time, surgical microscopes began establishing roots, but adoption was stalled for nearly 50 years as the optics and working distance were improved.3 Although superiority was shown nearly 25 to 30 years into development, overcoming the surgical preference and popularity of loupes proved to be the largest barrier to entry.3
Supplemented with coaxial illumination, hands-free design, and extended depth of focus, the modern-day microscope evolved into an irreplaceable commodity for visualization.1-4 When studied extensively across surgical specialties, a strong correlative effect exists between improved visualization and fewer intra-operative complications.3,5,6
Within ophthalmology, we can appreciate pervasive evidence of that evolution from monocular loupe to stereo-microscope design and manual pupillary stretching to intracameral pharmacodilation. It is safe to say this surgery's primary focus and development has always been centered around visualization.
Addressing the challenges of implementing new visualization tools
Though the overall improved safety profile was established, the wielding of new technology can be burdened with new-fangled revelations and unusual challenges. Roughly 10 years following the first literature describing extracapsular cataract surgery performed beneath an operating microscope, case reports began to crop up reporting microscope light-induced maculopathies.4
The first reported case series was in 1983 by McDonald et al., who described characteristic macular lesions in six patients following extracapsular cataract extraction with placement of posterior intraocular lenses (IOLs).7 On the first or second post-operative day, the investigators found an oval area of mild yellow-white discoloration with fluorescein angiography, unmasking sharply circumscribed juxtafoveolar lesions.
Following the development of a temporary paracentral scotoma, most individuals noted a functional return to normal over a reasonable time frame, with no long-term studies materializing to investigate the deleterious effects.7 Within the year, David J. McIntyre, MD, FACS, went on to add an ultraviolet (UV) and eclipse filter, decreasing the amount of light making its way into the pupil by up to 75% when the “red-reflex” wasn’t required.3
The battle over intraocular lenses
Interestingly, at about the same time, a raging battle was occurring over the utility of intraocular lenses versus aphakia. Irvine et al. reported to the American Ophthalmologic Society that these retinal lesions were due to an IOL increasing focusing power and allowing passage of shorter wavelengths of light, thereby inducing irreversible damage.8
Possibly distracting from the root cause, the microscope light, IOLs, and pseudophakia became the standard of care. Many subsequent studies merely encouraged physicians to take heed of these warnings, given the phototoxic potential of unfiltered coaxial illumination with little else in the way of resolution.7,8
Fast forward to today, there are scattered reports of macular phototoxicity from various light sources in both the anterior and posterior segment literature.9,10
Light-associated maculopathy
To date, there still exists much controversy over the relationship between short-wavelength light and age-related macular degeneration. There are unexplained phenomena, such as negative dysphotopsias, that have yet to be elucidated and challenging cases where visualization is still a concern.11
Remarkably, light-induced maculopathy was only explored if there were findings on clinical exam, but there is evidence from primate studies to support that somewhere between 4 to 7.5 minutes of direct “low setting” 11.7mW/cm2 coaxial light is enough to cause histological changes at the level of the retina, likely depicting a spectrum disorder rather than a binary one.7,8
Understandably too, whether or not the likely cause of findings and symptomatology is the light microscope, there were no alternatives in which to provide a safe and effective surgery.
The emergence of stereoscopic high-definition visualization
Over a 15-year development period, stereoscopic high-definition visualization systems are now available for routine use in ophthalmic surgeries.12 Posterior segment surgeons quickly adopted them, given the increased depth of focus, greater magnification, and precise focus, augmenting measured and delicate maneuvers.
Conversely, the anterior segment surgeons have been slower to adopt due to the inconvenient box location, requirements for efficient and high volume setups, and the roughly 100 milliseconds of lag that presented on initial models.12
However, with the potential for decreased size, improved ergonomics and teaching, built-in aberrometry, digitally-displayed toric, phaco, fluidics overlays, and improved efficiency, it would seem to be the next evolutionary step in surgical safety and improved outcome measures.
Moreover, one vastly interesting area of focus with stereoscopic high-definition visualization systems is the unique ability to digitally up-gain real-time images in low-light settings, thereby decreasing dependence on coaxial light for visualization.13
Albeit not a large consideration for many surgeons, given the lack of options with traditional microscopy in the past, recent studies would indicate that decreasing coaxial light may correlate with improved visual outcomes and faster recovery.13
Currently available digital ophthalmic microscopes
At the time of this writing, four comprehensive digital ophthalmic microscopes are available for commercial purchase: Alcon’s NGENUITY, Bausch + Lomb’s SeeLuma, Beyeonics’ Beyeonics One, and Zeiss’ ARTEVO 800. Given my experience with two systems, we can go into some depth regarding some of their unique features.
NGENUITY microscope
First, Alcon’s NGENUITY microscope provides high-definition, three-dimensional (3D) visualization of the surgical field, allowing surgeons to perform delicate and precise procedures with enhanced clarity, detail, and magnification. As a stand-alone system, NGENUITY confers the unique ability to be attached to almost any traditional microscope and transform it into a digital scope.
A pair of highly sensitive single-chip complementary metal-oxide semiconductor (CMOS) cameras with small controllable apertures and proprietary image processing software provides data to a 55-inch organic light-emitting diode (OLED) screen.
A recent software upgrade to 1.5 allows the operator to iris register to pre-operative data, thereby confirming the patient’s name, date of birth, correct laterality, and correct lens implant, all the while providing all pre-operative metrics on screen such as axial length and steep axis. Furthermore, the software allows for digital marking, on-screen phaco metrics, and digital filter enhancements, such as capsule detail mode.
Beyeonics One ophthalmic exoscope
The second device I’d like to discuss is the Beyeonics One ophthalmic exoscope. The Beyeonics One is a high-definition, fully digital imaging platform that enables surgeons to see magnified 3D images of the surgical field controlled through an immersive augmented reality (AR) surgical headset. Leveraging advanced technology found in aviation, we welcome a truly unique application for surgical digital visualization.
As an open and agnostic platform, the device allows for future integrations with electric medical records (EMRs) and picture archiving and communication systems (PACS), remote connectivity for service and enhancements, a meaningful teaching and training platform, and an all-in-one system enhancing efficiency and turnover.
Similar to other platforms, we can see value in digital overlays like toricity markings and centration. Unlike other platforms, the AR surgical headset can use head gestures to control frequent functions with ease and toggle through various overlays.
Final thoughts
It really should come as no surprise that big data will be the key to enhancing visualization and patient outcomes in the future of ophthalmic surgery. Transitioning from traditional to digital allows for real-time digital image processing, relevant overlays, on-screen metrics, quicker controls, “smarter” instruments, and, most notably, the integration of artificial intelligence (AI).
While the development from loupes to surgical operating room (OR) microscopes took several decades, it is possible to learn from our past to expedite our future. Many technologies in the field of medicine see their utility expire upon creation; however, it is our firm belief that integrating digital microscopes into the OR is only the beginning of something truly revolutionary.
If in training, I highly encourage you to get familiar with the instruments if available because it is hard to imagine a future without a digital OR.
