A Wide-angle Glimpse of the Latest in Capsulotomy Discoveries

by Joanna Lee 

At the 34^th Asia-Pacific Academy of Ophthalmology (APAO 2019) Congress, attendees were treated to a wide-angle view of the latest tools and technologies available for better cataract surgeries  ̶ from newest developments in intraocular lenses (IOLs), to an insightful debate on the tools currently in the market for capsulotomy.

These newly released technologies hold much promise for surgical efficiency and the potential for patients’ comfort and spectacle independence. However, as with every unchartered territory, there remains a need to test the efficacy and reliability of these technologies through trials in order to harness their full potential, especially for patient-specific conditions. 

New Lenses on the Block

A session, titled “New Technologies for Cataract Surgery”, began with Dr. Tim Schultz from the Department of Ophthalmology, University Eye Hospital Bochum, Germany, presenting a broad overview on IOLs. He reported about the latest clinical trials on enhanced depth of focus (EDOF) IOLs/presbyopia correcting IOLs which are “positioned somewhere between monofocal and multifocal IOLs”. 

So far, the few studies and cases reported have demonstrated good results for intermediate and near visual acuity with the lenses having advanced diffractive technologies, covering small aperture lens¹ technologies, as well as the manipulation of lens aberrations and asphericity.  

While various EDOF lenses like Lentis Comfort and Lentis Mplus (Oculentis GmbH, Berlin, Germany), Instant Focus (SAV-IOL, Neuchâtel, Switzerland), Precizon (Ophtec B.V., Groningen, The Netherlands), Mini Well Ready (SIFI Medtech, Catania, Italy) and others have been introduced in the market, Dr. Schultz highlighted the lack of randomized comparative studies in understanding the effectiveness of EDOFs. Out of 11 articles found on Pubmed, only one randomized controlled trial, a French study², was found. 

Dr. Schultz’s team’s prospective randomized trial showed the TECNIS Symfony (Johnson & Johnson, Santa Ana, California, USA) and the IC-8 (AcuFocus, Irvine, California, USA) presenting good refractive outcomes for intermediate and near visual acuity with better distance visual acuity for the IC-8 group, especially under mesopic light conditions. Symfony was shown to perform slightly better for near visual acuity, but the issue of halos was reported.  

What about the other lenses on the spectrum? Dr. Gerd Auffarth emphasized on the newer generation of lenses, which promise to reduce the ‘glistening’ effect in patients. The latest enhanced monofocal IOLs, like the TECNIS Eyhance (Johnson & Johnson, Santa Ana, California, USA), are developed from optical technology “based on a continuous asphericity of a higher order”, meaning a continuous power change from the periphery to the middle of the lens. 

Dr. Auffarth was also involved in one of the trials two years ago. “It’s not an EDOF lens, but it allows for better targeting for on-spot refraction, giving a little bit more refractive tolerability and slight improvements in intermediate vision,” he shared.

There’s also a type of hybrid between EDOFs and monofocals, as seen in the Santen lens, a two-ringed hydrophobic lens working under a diffractive principle under trial in Heidelberg, Germany, targeting distance and intermediate acuity.

Dr. Auffarth also covered the application of new technologies like reversible trifocality, where supplemental IOL implantations are added on to achieve spectacle independence and reduce dysphotopsia.

Adjustable IOL Technology

The latest trends in adjustable IOL technology, according to Dr. Burkhard Dick, includes IOLs requiring a secondary procedure for power adjustment (multi-component lenses). He gave examples of the PreciSight Lens (InfiniteVision Optics, Strasbourg, France) and Harmoni (ClarVista, Aliso Viejo, California, USA) that allow for customized prescription with a minimized need for touch-ups. Other potential indications were for increased chances of secondary IOL interventions, for instance, where there is anticipated refractive change (mid- or long-term) for post-keratorefractive surgery, or for multifocals or EDOF optics to allow for neuroadaptation, as well as for pediatric cataract to fix refractive changes over time.

Another modality was non-invasive IOL power adjustments, which can be done via a femtosecond laser procedure known as laser-induced refractive index change (LIRIC). Differing widely from the laser-assisted in situ keratomileusis (LASIK), LIRIC is a sub-threshold treatment that changes the refractive index caused by multi-photon absorption of ultra-short laser pulses. This can be done either intra-corneal or in silicone or hydrogel or even dye-doped polymers. It can be used to treat sphere or cylinder, higher order aberrations (HOAs) and presbyopia. LIRIC basically enables writing an optical correction in a design of a thin Fresnel lens. 

The development of lenses based on refractive index shaping (RIS) principles is gaining traction. Since its first reports in 2011³, RIS technology lenses, like those from Perfect Lens (Irvine, California, USA), were able to modify IOLs in live rabbit eyes and add or cancel IOL multifocality in a model eye; meanwhile, those from Clerio Vision (Rochester, NY, USA) have demonstrated laser-induced refractive index change in a living human cornea. 

Excitement still remains over light adjustable lenses (LAL). After having performed nearly 500 LAL implants along with trials, Dr. Dick shared his insights, saying these photosensitive silicone materials have shown promise for spherocylindrical errors, post-keratorefractive surgery eyes, long or short eyes, customized near adds, and adjustable monovision. 

“The LAL technology is ready. It’s coming to the US, and we’ve already had trials in Europe,” shared Dr. Dick. “It has great opportunities to improve refractive outcomes. However, the individually customized treatments for RIS change would be a big competitor for the LAL technology.”

A Look at MiLoop and Intraoperative OCT

Dr. Sumitra Khandelwal from Baylor College of Medicine in Texas, USA, shared new tools, particularly the MiLoop, that her team has been working with. The MiLoop fills the gap where femtosecond and chopping methods could not break dense fibrotic plates. 

It is a technology based on interventional medicine with an ultra-elastic, memory-shaped thin filament. It does centripetal (out-in) cutting with minimal stress on the capsule, versus traditional centrifugal (in-out) nuclear cracking. The MiLoop doesn’t insert like a typical IOL, so Dr. Khandelwal presented a video to show its cutting and cleaning out (of the cortex) capabilities. Dr. Khandelwal said she also utilizes the MiLoop for poor views in her transplants and cornea surgeries. She related how the tool is useful to clean out cortical material and for some patients, it clears the way for a Descemet’s membrane endothelial keratoplasty (DMEK) procedure.

“The key is to trust the device and focus with a very steady hand,” Dr. Khandelwal said, explaining how to use the tool effectively. However, she advised caution when considering its use for cases such as posterior subcapsular cataracts, as MiLoop tends to loosen the cortex. 

Another tool highlighted was the intraoperative OCT (i-OCT). Although it has been around for a few years now, the i-OCT is still a relatively new technology. Dr. Thanapong Somkijrungroj, uveitis and retina specialist from Chulalongkorn University, Bangkok, Thailand, demonstrated its benefits through videos of several case studies, including a double-rhexis surgery. The i-OCT guided a membranorhexis using forceps to avoid anterior capsule damage, following a capsulorhexis.  

Dr. Somkijrungroj shared that for his practice, his i-OCT is already conveniently integrated with the microscope used during surgery, so that the patient won’t need to be moved to a separate i-OCT machine for checking during the procedure.

A Friendly Debate on Capsulotomy Devices

The session culminated in a friendly “debate” on capsulotomy devices. Dr. Soon-Phaik Chee argued for femtosecond laser-assisted cataract surgery’s (FLACS) advantages, which included the ability to do precise, round cuts on lenses with shallow anterior chambers depths. Despite its size and cost and a 10-year record, FLACS can be also used for refractive procedures and lens fragmentation. 

“More studies are needed for Zepto (Aequus, Vancouver, Canada) and CAPSUlaser (Excel-Lens, California, USA) to prove their safety and efficiency in the eyes of different sizes. There are many cataracts which femto can handle better than manual, which the Zepto cannot and the CAPSUlaser may not,” Dr. Chee said in her summary. 

For the Zepto capsulotomy device, Dr. David Chang demonstrated through 20 cases how the device is suitable for more complex cases, such as anterior capsular fibrosis, brunescent lenses, mature lenses, and traumatic cases. It also allows for a normal sequence with convenience of its small size. 

“It’s really about having different options,” shared Dr. Chang. “Zepto is an instrument you can plug in separately, and I think surgical sequence is important. Start with something that preserves a normal surgical efficiency and does not require a huge investment. That’s why we think it’s a wonder,” he added.

Finally, the CAPSUlaser’s potentials were examined, as Dr. Richard Packard expounded on its effectiveness while pointing to a few studies.^4,5 Small in size, CAPSUlaser is cost-effective compared to the Zepto or FLACS. It gives 360-degree IOL coverage and allows for more stretching of the capsulotomy than other techniques without negative effects. It also offers greater accuracy of sizing, circularity and centration incision. Furthermore, it performs extremely well when comparing published results of femto-laser and manual capsulotomy. 

Editor’s Note: APAO 2019 was held in Bangkok, Thailand, from March 6 to 9, 2019. Media MICE Pte. Ltd., CAKE Magazine’s parent company, was the official media partner at APAO 2019. This article is based on the “New Technologies for Cataract Surgery” session held as a part of APAO 2019. Reporting for this story also took place at APAO 2019.

References:

1.  Dick HB, Piovella M, Vukich J, et. al. Prospective multicenter trial of a small-aperture intraocular lens in cataract surgery. J Cataract  Refract Surg. 2017;43(7):956-968. 

2.  Cochener B, Boutillier G, Lamard M, Auberger-Zagnoli C. A comparative evaluation of a new generation of diffractive trifocal and extended depth of focus intraocular lenses. J Refract Surg. 2018;34(8):507-514. 

3.  Xu L, Knox W H, Demagistris M, Wang N, Huxlin KR. Noninvasive intratissue refractive index shaping (IRIS) of the cornea with blue femtosecond laser light. Invest Opthalmol Vis Sci. 2011;52(11):8148-8155. 

4.  Daya S, Chee S, Ti S, Packard R, Mordaunt DH. Comparison of anterior capsulotomy techniques: Continuous curvilinear capsulorhexis, femtosecond laser-assisted capsulotomy and selective laser capsulotomy. Br J Ophthalmol. 

5.  Stodulka P, Packard R, Mordaunt D. Efficacy and safety of a new selective laser device to create anterior capsulotomies in cataract patients. J Cataract Refract Surg. 2019;45(5):601-607.