Latest Advances in Cataract Surgery

Experts Tell All

by Tan Sher Lynn

At the recent annual meeting of the American Society of Cataract and Refractive Surgery (ASCRS 2020), which was held virtually on May 16 to 17, the latest advances in cataract surgery were among the hot topics discussed — in particular, surgical systems, instruments and devices.

Below are some of the experts’ takes on these innovations.

Reducing occlusion break surge in cataract surgery

Occlusion break surge during phacoemulsification (PKE) cataract surgery can lead to potential surgical complications. According to Dr. Kevin M. Miller from the David Geffen School of Medicine at UCLA in Los Angeles, USA, anterior chamber stability during cataract surgery is essential for patient safety and occlusion break surge risks this stability. Surge volume factors include PKE system (hardware), operating settings (software), and eye compliance.

In an experimental study, he and his colleagues characterized post-occlusion break surge volume (SV) with the Centurion Active Sentry peristaltic system (CAS; Alcon Inc., Geneva, Switzerland); Whitestar Signature Pro peristaltic system (WSP; Johnson & Johnson Vision, Jacksonville, Florida, USA); and Stellaris PC venturi system (SPC; Bausch + Lomb, Quebec, Canada), under varying intraocular pressures (IOP), vacuum limits (Vac), and aspiration rates (Asp). To provide surgical measurements, a mechanical eye model that mimics the compliance of the human eye was used to imitate the anterior chamber volume-pressure change behavior. Using this model, the SV of the systems was characterized at a Vac of 300 to 650mmHg, IOP of 30 to 80mmHg, and Asp of 20 and 40cc/min (the SPC does not have an Asp setting).

“We found that SV is heavily dependent on the phaco system used and its surgical settings,” shared Dr. Miller. “CAS had a significantly lower surge volume at all surgical settings compared to WSP and SPC. CAS also had the highest level of case-to-case consistency compared to WSP and SPC,” he further explained.

Effects of torsional power during PKE

Meanwhile, Dr. Santaro Noguchi from Saneikai Tsukazaki Hospital in Japan examined how torsional amplitude, sleeve type, tip type and IOP settings affect the intraocular perfusion supply. He found that the infusion rate during PKE is greatly affected by torsional power (TP).

Using the Centurion Vision System (Alcon), the weight of BSS (balanced saline solution) Plus 500 (0.0184%) injected during torsional PKE was measured. He discovered that except for the balanced tip+ultra sleeve setting, all perfusion flow tended to decrease due to the influence of TP.

In particular, in the case of TP with 80% or more, the decrease of perfusion rate was remarkable. Dr. Noguchi concluded that the anterior chamber is likely to become unstable in cases requiring high TP, and suggested the use of the ultra sleeve especially for hard nuclei, and that it is better to raise IOP only when TP is high.

Maximum visual outcomes, minimum iatrogenic effects

The goal of modern cataract surgery is to produce excellent visual outcomes while minimizing iatrogenic effects and improving procedural efficiency.

Dr. David M. Lubeck and colleagues performed a systematic literature review (SLR) to evaluate recent clinical evidence comparing safety, efficacy and efficiency of different PKE systems.

They searched through PubMed and EMBASE/MEDLINE databases to compare clinical efficacy and safety data for the Centurion Vision System versus other PKE systems. From 6,132 records, they identified 27 relevant articles and extracted data from eight articles comparing the Centurion and Infiniti Vision Systems (Alcon).

“While the Centurion Vision System maintains the excellent safety profile established by the Infiniti Vision System, results show that the Centurion

Vision System uses significantly less cumulative dissipated energy (CDE),” observed Dr. Lubeck.

“The reduction of CDE is associated with less endothelial cell loss (ECL) and corneal edema, and may translate to better visual outcome and patient recovery. Besides, the Centurion Vision System uses similar or less fluid volume and achieves shorter lens aspiration times than the Infiniti Vision System. Superiority in these efficiency measures may result in reduced ocular trauma, quicker patient recovery and superior visual outcomes,” he added.

Advantages of a new laser capsulotomy device

Dr. Erik L. Mertens, physician, CEO and medical director of Medipolis Eye Centre in Antwerp, Belgium, shared his early clinical experience of using the CAPSULaser (Excel-Lens, California, USA), a new selective laser capsulotomy (SLC) device, in routine cataract surgery.

The CAPSULaser is an SLC technique using a 590nm orange wavelength laser, which is selectively absorbed into a trypan blue stained capsule to create a perfectly sized, centered and circular capsulotomy.

“First, the CAPSULBlue (trypan blue 0.4%) is used to create a deep stain of the anterior chamber. It was left on for 60 seconds before washing off. Next is to position and focus the patient interface and laser on the anterior capsule. Then, the laser is activated and in one-third of the second, a 5mm circular capsulotomy is performed,” shared Dr. Mertens.

Dr. Mertens concluded that the CAPSULaser has an easy learning curve using standard techniques, and the workflow and surgery time of CAPSULaser are equivalent to conventional cataract surgery.

“The capsular edge created by the CAPSULaser is stronger than the one created by femtosecond laser-assisted cataract surgery (FLACS), due to the doubling of capsular edge thickness,” he shared. “This is because thermal changes of the anterior capsule transformed regular ordered collagen type IV to amorphous collagen with increased elasticity. We also found that 100% of the CAPSULaser group have complete 360-degree capsulotomy coverage. In terms of economics, it is cost-effective, which means it will replace some FLACS systems and allow many smaller practices to adopt laser cataract technology,” he further explained.

Understanding corneal incision contracture

Cataract surgery is accompanied by various issues, one of which is corneal incision contracture (CIC), where the heat from the phacoemulsification needle is transferred to the incision site, which may cause collagen contracture.

Nathan R. Jensen and colleagues of the University of Utah Health, USA, aimed to understand the role of an ophthalmic viscosurgical device (OVD) in heat, specifically at the site of incision, in a scenario where vacuum is present versus when vacuum is obstructed.

In the study, a thin membrane was placed on top of a chamber containing BSS. An OZil (Alcon) handpiece was placed into the chamber, piercing the membrane. Next, 0.1ml of BSS, Viscoat (Alcon), ProVisc (Alcon), DisCoVisc (Alcon) or Healon5 (Johnson & Johnson Vision, California, USA) were placed on top of the membrane with the temperature gauge, which recorded the temperature at time zero, 10 seconds, 20 seconds, and 30 seconds.

The authors found that in the absence of both vacuum and flow, each OVD/BSS had an average increase of temperature from baseline to 30 seconds of at least 6.88°C and an average difference of 8.34°C.

“In the absence of vacuum, the average final temperature of DisCoVisc, Healon5 and Provisc was below that of the average final temperature of BSS,” explained Jensen. “In the presence of vacuum, BSS featured the greatest change from the initial temperature to the final temperature. Both parts of the study demonstrate the ability of temperature to rise even across a thin membrane, though the presence of vacuum mitigated that rise,” he added.

Gaining confidence in proper use of new instruments

Meanwhile, the new miLOOP (Carl Zeiss Meditec, Jena, Germany) is a micro interventional device designed to deliver low energy endocapsular lens fragmentation, mainly in dense cataract and complicated cases.

Dr. Matteo Piovella, president of the Italian Ophthalmological Society, and colleagues examined the use of miLOOP technology in 47 patients over 58-years-old with medium/hard cataracts.

In the study, the metal loop was inserted in the capsular bag and opened throughout the edge of the hydrodelineation line. Once the loop was in the proper vertical position, it was retracted to split the nucleus into two parts.

Dr. Piovella noted that a learning curve is involved in the adoption of the miLOOP technology and the device should be used in simple cases first to gain confidence and to avoid devicerelated complications. He added that in one case, the loop did not match the capsular bag and caused mild zonula damage with no significant event.

He concluded that miLOOP adoption in dense cataract and complicated cases reduces phaco energy by 50%, reduces I/A fluid use by 30%, and makes hard nucleus cataract removal more controlled and efficient.

Editor’s Note:

ASCRS 2020 Virtual Annual Meeting — the world’s first-ever successful virtual ophthalmic conference — was held on May 16 to 17, 2020. Reporting for this article also took place during the virtual ASCRS 2020 conference, where CAKE magazine’s parent company, Media MICE, was the only exhibiting independent media.