Modern cataract surgery with simplified technology: new trend?

It is the framework which changes with each new technology and not just the picture within the frame. —Marshall McLuhan The development of ultrasonic phacoemulsification by Charles Kelman is considered a paradigm shift in cataract surgery because it allowed extracapsular capsular extraction to be performed through small incisions.1 However, challenges related to conventional phacoemulsification include the requirement for complex electronic consoles, large operating room footprint, complex fluidics to cool the ultrasonic tip, use of a foot pedal coupled to the handpiece, and high capital expenses, including upfront investment related to the cost of the phacoemulsification machine, installation, continuous maintenance, and service contracts. The specific financial aspect is likely the limiting factor to the widespread adoption of ultrasonic phacoemulsification in low-resource settings.2–4 Some companies are working on simplifying equipment used in modern cataract surgery, and although some projects are in early phases of development, at least one is already available in the market. A new handheld lens fragmentation device has been developed by Tsontcho A. Ianchulev, MD, for noncavitating, nonemulsifying fragmentation, and nuclear segment removal. It uses mechanical agitation for nuclear disassembly instead of ultrasonic energy and does not require a console or foot pedal for its functioning. It was approved by the U.S. Food and Drug Administration in 2022, and it is currently marketed as miCOR by Carl Zeiss Meditec AG. The nondisposable handpiece of the system is a handheld lens-pen device, which connects to a bag of a balanced salt solution on a standard intravenous pole through a disposable head. This latter includes tubing and the irrigation/aspiration (I/A), as well as a dynamic finger lever or throttle that actuates the device, with an agitation mechanism oscillating at a subultrasonic frequency of 40 Hz. The lens agitator mechanism is engaged when the finger lever or throttle is depressed to approximately 65%. The handpiece contains the rotating power drive and electronic controls; through the disposable head, it can be attached to various disposable tips for the different surgical steps. The lens removal tip is smooth and rounded; after nucleus and epinucleus removal, the tip is changed to a silicone I/A–specific tip for cortical removal. The function of the I/A tip can also be changed to a polishing mode. The system maintains a 2.4 mm incision size as standard phacoemulsification procedures.3,4 Studies describing initial clinical/surgical experience with the new handheld fragmentation device have started to become available in the Journal of Cataract & Refractive Surgery. Ianchulev et al. reported on a retrospective case series including 665 consecutive eyes undergoing cataract surgery by 12 surgeons from different ambulatory surgical centers in the United States, all with extensive surgical experience.3 The authors investigated the intraoperative performance and lens fragmentation efficacy of the handheld device in cataracts of different grades. Before lens extraction with the handheld device, the miLOOP (Carl Zeiss Meditec AG), a super-elastic nitinol memory-shaped loop used to fragment cataracts using centripetal mechanical force, was used to perform precuts in some cases across all cataract grades; otherwise, the handheld device was used for both segmentation and fragmentation.3 Of the cases, 6%, 70%, 19%, and 5% were graded intraoperatively by the surgeons as 1, 2, 3, and 4 nuclear densities, respectively. Successful nuclear fragmentation, lens extraction, and cortical removal were achieved in all eyes without requiring the use of phacoemulsification. Lens removal times were faster with lower cataract grades, and fluid used for nucleus extraction increased with increasing cataract grades. The time needed for lens extraction was less than 5 minutes for the densest lenses. Fluid usage averaged 50 mL among all cases, ranging between 34 mL and 53 mL. It is noteworthy that the total volumes used during phacoemulsification procedures reported in the literature are generally higher, including during bimanual and micro-coaxial phacoemulsification with torsional ultrasound.5 There were 3 cases of capsular tear in 665 surgeries for a rate of 0.45%, and no other emergent adverse events were described.3 The initial experience and learning curve of a single experienced surgeon with the handheld device have more recently been described by Beniz et al., who assessed time required for each surgical step during the procedure, effect of nuclear density on procedure time, postoperative outcomes, and rate of complications.4 This was a single-center, noncomparative, retrospective study including 61 consecutive eyes of 51 patients with cataract, aged 72.2 ± 7.6 years. With increasing surgical experience, there was a statistically significant decrease, in seconds, in the mean time for all steps combined, as well as for the nuclear removal step and the cortex removal step. Higher nuclear density significantly increased the mean active surgical time and the time required for the nuclear removal step. The surgeon noted that the device works best with chopping techniques (eg, horizontal or vertical chop) or nonphacoemulsification mechanisms for nuclear disassembly (eg, prechopper or nitinol loop). The mean amount of fluid used in each surgery was 27.1 ± 6.5 mL. The anterior chamber remained extremely stable throughout lens extraction and cortex removal. The mean preoperative distance-corrected visual acuity was 0.23 ± 0.13 logMAR for eyes without ocular comorbidities, changing to 0.12 ± 0.07 logMAR at 1 month postoperatively. One posterior capsular tear occurred, but it was not attributed to the lens extractor because it occurred during a chopping maneuver. No thermal damage to the corneal wound was observed. All cases presenting with anterior chamber inflammation, corneal edema, and intraocular pressure (IOP) spike on the first day after surgery recovered well and showed no evidence of anterior chamber cells, corneal edema, or further IOP increase at the end of the first follow-up month.4 At the Moran Eye Center, experimental independent studies have been performed to evaluate some specific parameters of the handheld device, which have not yet been thoroughly assessed in the currently available clinical/surgical studies.6 A rabbit study quantified damage to corneal endothelial cells by using the handheld device with the lever only half depressed (without engagement of the lens agitator mechanism) or fully depressed, and compared it with standard phacoemulsification. Staining of the corneal buttons with trypan blue and alizarin red suggested that damage from the device, when the lens agitator is engaged is comparable with that of standard torsional phacoemulsification.6 In another study, the efficiency and chatter of the handheld device with increasing bottle heights was evaluated in vitro, using 2.0 mm cubes cut from formalin-fixated porcine lens nuclei placed in an artificial chamber filled with solution. Increasing bottle height from 37 to 54 cm resulted in a significant increase in efficiency, but a bottle height of 75 cm showed no further increase. The decreased efficiency seen at lower bottle height was apparently related to increased chatter.6 A third study was a calorimetric set-up evaluating the amount of energy delivered to the anterior segment by 3 different phacoemulsification platforms and the handheld device, which showed that the mean energy produced by the handheld device was significantly lower than that produced by the phacoemulsification platforms evaluated.6 Feedback provided by surgeons using the handheld device will likely lead to changes to its current version. Some possible improvements suggested by the surgeon in the study by Beniz et al. include incorporation of an active reflux mode, incorporation of tools to switch to bimanual irrigation and aspiration, and a change to the sound produced by the device, which is not in a feedback-tone pattern.4 Although an anterior vitrectomy tip is included in the current version of the device, detailed description and reviews of it are apparently not yet available. The handheld device provides a new alternative for cataract extraction, with potential advantages that include a minimal footprint, portability, low-capital expenditure, and workflow efficiency. It is anticipated that studies directly comparing surgery performed using this device or traditional phacoemulsification will be undertaken; thus, efficacy, safety, complication rates, and detailed cost analyses can be fully assessed. Results from future studies, and time will tell if adoption of this new, simplified technology approach to modern cataract surgery will be widespread, or more limited to office-based cataract settings, or low-resource environments.