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FROM THE EDITOR

Three-dimensional (3D) visualization for intraocular surgery: necessity or nicety

Srinivasan, Sathish FRCSEd, FRCOpth, FACS

Author Information
Journal of Cataract & Refractive Surgery: March 2021 - Volume 47 - Issue 3 - p 287-288
doi: 10.1097/j.jcrs.0000000000000595
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Technology is a useful servant but a dangerous master.

—Christian Lange

The first description of the microscope dates to the 17th century. Our predecessors used simple presbyopic corrections, later increased to overcorrections and coupled with the use of base in prisms to enhance their surgical view. Around 1820, the limited magnification available with a single-lens system (simple microscope) was overcome by the use of compound lens (ocular and objective lenses), systems that naturally evolved to the introduction of compound microscopes. This enabled the surgeon to have a greater working distance from the specimen by allowing for finite focal lengths outside the optical system. Several years later, Lister and Dollond introduced the achromatic lens as a standard in microscopy, which has been continued and improved on to the present day. In 1846 Carl Zeiss, a German machinist, opened a microscope factory in Jena, Germany. Ernst Abbe, a physicist working with Carl Zeiss, in 1857, derived new mathematical formulas and diffraction theory that revolutionized lens making. In 1884, Otto Schott joined Zeiss and brought scientific rigor to optical glass manufacturing.1

These “3 musketeers” are to be credited for taking microscopy to the next level. However, it was not until 1921 that the microscope made its clinical debut when the Swedish otologist Carl-Olof Nylen used it for the first time in ear surgery in 1921.2 This monocular microscope was rapidly replaced by a binocular microscope developed in 1922 by Gunnar Holmgren.3 Because of its limited field of vision, very short focal distance, and poor illumination and instability, this microscope was seldom used initially. The first reference to the use of a binocular microscope in ophthalmology was reported by Harms in 1953.4 The earliest reference to a stereoscopic operating microscope dates back to 1956 when Becker documented its usefulness in examining children under anesthesia.5

The modern standard operating microscope has a vertically aligned optical system with an obliquely placed illuminating system powered by a halogen light source. In this, the light is delivered to the optical system with a fiberoptic cable to reduce heat generation. These microscopes use an output module interface (OPMI) featuring a single light beam. The traditional single OPMI illumination beam is aligned 2 degrees off the coaxial viewing alignment, thus providing shadows on the operating field. In 2007, Carl Zeiss Meditec AG, introduced a new generation of ophthalmic operating microscopes that provided stereo coaxial illumination with a xenon light source. The system consisted of a 6-degree oblique illumination and 2 separate coaxial illuminating light sources that could be independently controlled intraoperatively by the surgeon. This system was a true step up that enhanced the intraoperative retroillumination and red reflex. Later, in 2013, we saw the introduction of LuxOR (Alcon Laboratories, Inc.) that was designed to provide a larger diameter red-reflex zone that is not affected by pupil size, microscope or lens position, or eye movement.6 The optics in this microscope consist of 2 overlapping, nearly collimated light beams (ie, parallel rays and each ray with approximately 10 degrees of divergence) from halogen illumination sources located beneath the objective lens and are aligned with the microscope oculars; these 2 illumination beams are encompassed by a third, oblique light beam. These advanced optics provided the surgeon with a red reflex that is 6 times larger than a standard microscope’s red reflex. This allows the surgeon to operate without adjusting the microscope when the eye tilts or shifts.7 In 2015, Leica Microsystems introduced an operating microscope with an LED light source, with stereo coaxial illumination and enhanced proprietary optics, which provided an increased depth of field. Although the past 2 decades have brought us newer developments in the optics of traditional operating microscopes, at the same time, major strides have been made in exploring and developing alternating viewing formats for intraocular surgery. Stereoscopic high-definition visualization systems have become a clinical reality. These systems use a 3D camera attached to a microscope. The camera displays the image of the surgical field on a high-definition display screen that the surgeon visualizes using 3D spectacles. The NGENUITY 3D Visualization System (Alcon Laboratories, Inc.) and the ARTEVO 800 (Carl Zeiss Meditec AG) are the 2 currently commercially available 3D visualization platforms, whereas a third one, Beyeonics system (Beyeonics), is currently undergoing U.S. Food and Drug Administration trials.

It seems that posterior segment surgeons have adapted to this technology sooner. Although there are several reports on the use of this technology in retinal surgery, there is a paucity of data regarding cataract surgery. Weinstock et al.,8 in 2019, published a large retrospective study comparing the surgical time and complication rate between heads-up cataract surgery compared with traditional microscopes and showed noninferiority of the 3D system. Qian et al.9 published a small prospective randomized clinical trial comparing the efficacy and safety of the 3D digital visualization system with the traditional operating microscope during phacoemulsification and demonstrated noninferiority of the 3D system to traditional viewing.

In this issue, Rosenberg et al. (page 291), in a small retrospective study, demonstrate for the first time, to my knowledge, that the mean light intensity used during cataract surgery with the NGENUITY 3D Visualization System was significantly less compared with the traditional system, and of interest, this translated to patients achieving better visual acuity at postoperative day 1.

I have had the opportunity to use the ARTEVO 800 digital operating system in my clinical practice for a period of 3 weeks. My personal experience mirrors the published literature in that it enhanced my intraoperative depth perception, provided an excellent intraoperative view, and provided greater comfort owing to better ergonomic seated posture.

The essence of ophthalmic surgery is accuracy. The higher the intraoperative magnification the better would be the dexterity and intraoperative control of instruments, which should improve surgical outcomes. The introduction of digital microscopes with heads-up 3D visualization is certainly an exciting step forward that has the potential to enhance not only patient care but also surgical training. Certainly, more prospective randomized clinical studies are required to tease out the benefits of this technology for patients and surgeons. We should continue our collaboration with the industry to develop this technology with wisdom and prudence because clinicians will embrace technology as long it has meaningful clinical benefits.

REFERENCES

1. Murdy A. The history of the microscope for use in ear surgery. Am J Otology 2000;21:877–886
2. Nylen CO. The microscope in aural surgery; its first use and later development. Acta Otolaryngol 1954;116(suppl):226–240
3. Holmgren G. Operations on the temporal bone, carried out with the help of the lens and the microscope. Acta Otolaryngol 1922;4:386–393
4. Harms H. Augenoperationen unter dem binokularen Mikroskop [in German]. Ber Dtsch Ophthal Ges Heidelberg 1953;58:119–122
5. Becker B. The Zeiss operating microscope. Am J Ophthalmol 1956;42:302–303
6. Alcon Research I. LuxOR LX3: superior technology for superior visualization. Available at: https://www.myalcon.com/products/surgical/luxor-lx3-with-q-vue-ophthalmic-microscope/depth-of-focus.shtml. Accessed January 24 2021
7. Cionni RJ, Pei R, Dimalanta R, Lubeck D. Evaluating red reflex and surgeon preference between nearly collimated and focussed beam microscope illumination systems. Tarnsl Vis Sci Technol 2015;4:7
8. Weinstock RJ, Diakonis VF, Schwartz AJ, Weinstock AJ. Heads-up cataract surgery: complication rates, surgical duration, and comparison with traditional microscopes. J Refract Surg 2019;35:318–322
9. Qian Z, Wang H, Fan H, Lin D, Li W. Three–dimensional digital visualization of phacoemulsification and intraocular lens implantation. Indian J Ophthalmol 2019;67:341–343
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