Cedric Schweitzer, MD, is an ophthalmologist based at the University Hospital Bordeaux in France.

Cedric Schweitzer, MD

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The femtosecond laser is widely used in ocular surgery, particularly in refractive surgery with LASIK flap creation or small incision lenticule extraction, as well as in corneal graft or corneal inlays for keratoconus. Owing to the very short pulse of the laser, the technology provides highly precise ocular tissue cuttings without causing collateral damage to surrounding structures.

The application of femtosecond laser to cataract surgery was the obvious next step of the technology and has led to femtosecond laser-assisted cataract surgery (FLACS) emerging as a recent breakthrough. However, it has required additional developments such as specific docking systems and real-time imaging to enable cuttings of the opacified crystalline lens to be made without distortion of ocular structures during the laser procedure. Safety zones to preserve surrounding structures within the eye also needed to be considered (Figure 1).

As expected, laser-created capsulotomy is more precise, circular and centred than manual capsulotomy. In addition, corneal incisions have more reproducible squared-edge architecture and greater resistance to leakage than manual incisions using a calibrated knife. Furthermore, the fragmentation of the lens provided by the specific pattern of femtosecond laser impacts within the lens significantly reduces the amount of ultrasound used to remove the remaining pieces of the lens during the phacoemulsification phase.

However, despite the femtosecond laser’s high level of technical capabilities in cataract surgery, the clinical benefit for patients remained unclear and a Cochrane meta-analysis could not determine the equivalence or the superiority of FLACS to phacoemulsification due to a very low certainty of the available evidence and the unclear risk of bias in included studies.

With cataract surgery being one of the most routinely performed operations in medicine, it became clear that such a comparison was necessary, not just for patients but for healthcare professionals and decision-makers as well, to enable them to provide recommendations and potentially facilitate the spread of the technology.

The FEMCAT trial was a large-scale, independent, randomised clinical study which took place at five centres in France. It was designed to compare anatomical, visual and refractive outcomes between FLACS and conventional phacoemulsification cataract surgery among 907 patients (1,476 eyes) who received either bilateral or a unilateral cataract surgery by one of these two methods. We included a wide range of cataract severity grades that were likely to be representative of the French population who undergo cataract surgery every year in France.

The success rate was defined by four relevant outcomes in cataract surgery: the absence of perioperative complications up to the 3-month visit; a best corrected visual acuity of 0.0 LogMAR or better; an absolute manifest refractive error below 0.75 dioptres; and the absence of significant change in corneal astigmatism between the preoperative visit at month 3 post-operatively.

The femtosecond laser was found not to be superior to phacoemulsification in cataract surgery and thus FLACS failed to provide an additional clinical benefit for patients despite its advanced technical performance. Indeed, we observed a high rate of uncomplicated surgery of 94.2% up to the 3-month visit without significant difference between the two groups. These results were recently reported in 

The rate of absolute manifest refractive error below 0.75 dioptres or 0.5 dioptres were up to 81.4% and 76.5%, respectively, again without significant difference between the two groups (Figure 2). Interestingly, we did not observe any difference in visual, refractive or anatomical outcome measures between the two groups whatever the cataract type or the cataract severity grade.

In order to provide robust data on a large sample size, the FEMCAT trial was designed to minimise the risk of bias. We strived to provide masking procedures until the last follow-up visit wherever we could, including having a sham laser procedure for patients randomly allocated to the phacoemulsification group. Additionally, an independent adjudication committee composed of three independent ophthalmologists masked to the trial allocation was designated to evaluate all adverse events for increasing objectivity in safety evaluation.

We also standardised all the associated procedures (IOL optical and biomaterial characteristics or phacoemulsification machines) in each centre to limit the risk of bias and to analyse only the safety and efficacy profile of the studied surgical procedures. Finally, four surgeons experienced in cataract surgery were involved in the trial at each centre. They were also likely to be representative of cataract surgeons in France.

FEMCAT was also a cost-effectiveness trial and so we collected all direct expenses related to the surgery using a real-life micro-costing approach based on detailed resources used during the surgery. It included the prices of items such as knives, viscoelastic products, syringes or cannulas; the expense of the laser and disposable docking systems; and all costs related to phacoemulsification machines.

We also estimated all inpatient and outpatient costs, including those related to the follow-up or rehabilitation care arising until the treatment success measurement was obtained using the French

national health data system, a claim database encompassing 98

.8% of the French population. With comparable clinical outcomes between the two groups, the cost of FLACS was significantly higher and thus the laser was found not to be a cost-effective procedure for cataract surgery.

Indeed, all inpatient and outpatient costs as well as all direct costs of surgical items or phacoemulsification machines were not significantly reduced in the FLACS group. Thus the financial loss incurred by laser was not compensated, even in part, by either better clinical efficacy or a significant reduction in other direct costs during the surgical procedure or thereafter.

It is likely that the technology’s expansion will need to be facilitated by a significant reduction in femtosecond laser procedure costs in the future, including those incurred indirectly, for example by phacoemulsification machines that are used to aspire the fragmented lens.

The femtosecond laser was confirmed to be reliable and precise regardless of the cataract severity grade or the clinical experience of surgeons in our trial. Also noteworthy was that the laser enabled reliable images of the anterior structure of the eye to be obtained irrespective of the cataract severity grade, even for very mature cataracts, and allowed for reproducible cuttings of ocular tissues in the FLACS group.

Moreover, we did not observe any significant adverse event during the femtosecond laser phase. We reported only six cases of incomplete capsulotomy without subsequent anterior capsule tear.

Ultrasound time and energy were also significantly reduced in the FLACS group. Finally, we can also confirm the learning curve of FLACS was short without significant adverse events seen in the first cases by each surgeon.

While FLACS does not provide an additional clinical benefit for patients over phacoemulsification cataract surgery today and was not found to be a cost-effective strategy in our trial, it is fair to acknowledge that this technology is still in its infancy and some perspective exists. Indeed, FLACS has provided new insights into anterior segment surgery, particularly in paediatric cataracts, by enabling posterior laser capsulotomy, which, when it is performed following crystalline lens extraction, could limit the risk of amblyopia related to the posterior capsule opacification.

Additionally, owing to the real-time imaging technology and the three-dimensional zones of laser treatment or safety zones the surgeon can define prior to the laser procedure, this technology can also improve the surgical outcomes of some severe anterior segment diseases such as severe capsulophimosis. The development of new IOLs that would be a better fit to the very precise and circular capsulotomy provided by the femtosecond laser machine could also help improve IOL stability or centration along the visual axis.

Furthermore, innovations such as new aspiration machines associated with the femtosecond laser could help limit the need to use the phacoemulsification machine and reduce the overall cost of the surgical procedure. Finally, FLACS may also pave the way to a new era of automation and robotics in cataract surgery.

In conclusion, we believe that the FEMCAT trial provides useful information that healthcare providers and decision-makers should consider before implementing this new technology in routine practice for cataract surgery. Although FLACS represents an innovation that could open new doors in ophthalmology, it is necessary to rationalise the overall costs of cataract surgery as well as consider the individual patient’s journey when considering whether or not it is appropriate to choose FLACS over phacoemulsification.

Figure 1. Real-time imaging system showing an automated recognition of anterior and posterior faces of the cornea, and anterior and posterior faces of the lens. The green zone is the laser treatment zone within the lens and the red zone is the safety zone based on the pupillary margin and the posterior capsule of the lens. 

(Image courtesy of Dr Cédric Schweitzer)

Figure 2. FEMCAT trial: Safety and efficacy analyses at 3 months in modified intent-to-treat populations.

Dr Schweitzer is an ophthalmologist at Bordeaux University Hospital in France and is the principal investigator of the FEMCAT trial, which was fully supported by a grant for the French ministry of social affairs and health. The French ministry of social affairs and health did not participate in the collection, management, statistical analysis and interpretation of the data or in submitted manuscripts. Dr Schweitzer has no financial disclosures.

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With its higher costs, FLACS failed to provide an additional benefit over phacoemulsification for patients or in healthcare settings, despite its advanced capabilities.

Femtosecond lasers and phacoemulsification go head to head in French trial

Thorough visualisation of the lens is important for safe and effective cataract surgery. This is best achieved when pupils are adequately dilated throughout the procedure. Although mydriatic eye drops produce the required dilation in most cases, mechanical intervention, namely hooks and additional incisions, is required when these pharmacological agents fail.

The Malyugin ring (MicroSurgical Technology) was developed as a safe alternative to traditional pupil-expansion approaches. It is square in shape and has four circular scrolls with eight points of fixation that ensure an evenly dilated circular pupil is achieved. The latest version is made of 5.0 polypropylene.

A stand-out advantage of the device is that the ring, with its diameter of 6.25 or 7.0 mm, can be inserted through main corneal incisions as small as 2.0 mm – a feature that enables the ring’s use at any time during the surgery and eliminates the need for additional incisions.

However, although the ring offers such advantages and reduces the challenges associated with operating on eyes with small pupils, it has an associated learning curve and must be mastered to avoid difficulties or complications during surgery.

Avoiding complications by mastering the surgical technique

The ring, which has been designed to make minimal contact with the iris during insertion and removal, is introduced into the eye using its own injector. Specifically, it is inserted through the primary corneal incision at the start of the phacoemulsification stage of surgery, although for eyes that experience unexpected intraoperative pupillary constriction, such as in intraoperative floppy iris syndrome (IFIS), the ring can be safely inserted at a later stage.

The injector must be used to move the ring forward and engage its distal scroll with the iris. It is important to then continue inserting the ring while moving the injector in a backward direction towards the primary incision.

Once the lateral scrolls emerge from the injector, they will latch onto the edge of the iris and the proximal scroll will emerge smoothly from the injector. The injector can then be completely removed from the eye in a quick and fluid motion.

I have used the ring for around 3 years and have operated on many eyes with conditions in which it is difficult to maintain pupillary expansion throughout surgery, such as pseudoexfoliation syndrome, traumatic iris and IFIS. While doing so, I have found that although the ring is easy to insert, care must be taken when attaching the proximal scroll as its correct engagement with the iris is important for avoiding complications.

Failure to do so creates a small risk of iris damage if the ring unexpectedly disengages during surgery. Furthermore, an accompanying device called the Malyugin Ring Manipulator (designed specifically to assist placement of the ring) or a Lester hook should be used in conjunction with the injector to ensure correct attachment of the fourth edge – the injector alone will not suffice.

Once correct attachment of the ring has been achieved, the next potential challenge to a surgeon new to the Malyugin ring is removal of the injector from the eye. While the injector usually exits from the eye with no problem, sometimes, resistance may be felt. If this happens, the surgeon simply needs to move the ring to the side a little to overcome the resistance.

Just as care needs to be taken to correctly insert the ring to avoid ocular tissue damage, the iris can be damaged if the ring is not removed with due care. The Malyugin ring is removed from the eye by reversing the process by which it was inserted, with a Lester hook required to lift the disengaged proximal and lateral scrolls from the iris.

The injector can then be inserted through the main corneal incision and hooked onto the proximal scroll. Once the injector and the scroll are firmly attached, the surgeon simply has to push the injector’s button backwards to start retracting the ring into the injector.

Iris damage can occur at this stage if the ring is removed too quickly and without checking that the last scroll is fully disengaged before beginning retraction. To avoid this, a Lester hook must be used to disengage the ring edges at 12 o’clock and 9 o’clock.

Once these are free, the ring can be retracted with complete confidence that the iris edge will not be caught and pulled. As soon as the ring is fully retracted, the injector can be removed from the eye.

This is the case of a 72-year-old male patient with exfoliative glaucoma. Given his history of tamsulosin use, he was identified as being at high risk of IFIS and I knew a Malyugin ring would most likely be required for his surgery.

Indeed, preoperative pupil dilation was poor and a Malyugin ring was used to produce sufficient dilation to proceed with surgery as safely as possible. Insertion and removal of the ring was performed following standard protocol and no iris damage occurred.

The Malyugin ring is an effective pupil-expansion device with minimal risk of intraoperative damage and no need for additional corneal incisions. It exhibits highly predictable behaviour throughout surgery.

Its injector facilitates the non-traumatic introduction and removal of the ring, and its square shape ensures that, once engaged, the pupil remains adequately dilated without being overstretched to a level that causes iris sphincter damage. By maintaining dilation, even in cases of IFIS, the device provides the room needed for a surgeon to complete phacoemulsification and fragment removal.

Despite these advantages, skill, experience and care are still required to use this ring in a manner that ensures iris damage is not caused by incorrect scroll engagement during insertion or disengagement prior to removal of the ring. However, having used this ring for several years without incident, it is clear that the risk of iris damage is minimal if care is always taken and a specific hook is used in conjunction with the injector during insertion and removal.

Dr Schweitzer is an ophthalmologist based at the University Hospital Bordeaux in France.

The Malyugin ring is a safe alternative to traditional pupil-expansion approaches in cataract surgery. Here, best practice for safe surgery and a case study are described

Managing complications using the Malyugin ring

	Cataract surgery in patients with small pupils is associated with a raft of complications including damage to and prolapse of the iris into a wound, the creation of a small anterior capsulorrhexis (leading to anterior capsule damage), incomplete removal of the cortical material, postoperative inflammation and a higher risk of posterior capsule rupture.

Related: Overcoming challenges of pre-existing ruptured posterior capsule 

	A small pupil also hampers visualisation of the peripheral capsule, making it difficult to ensure that the lens and haptics are placed completely in the bag.

	Achieving and maintaining adequate mydriasis is crucial in preventing serious complications. However, we are fortunate to have more interventions and instruments available than ever before to help us deal with these difficult cases.

	There are a number of options for increasing pupil size, including the use of intracameral mydriatics such as Shugarcaine and epi-Shugarcaine, viscodilatation and pupil-expansion devices. The pupil-expansion devices available include plastic and metal iris hooks, Clarke and Siepser rings, the Graether expander (Eagle Vision Inc.), the 5S iris ring (Morcher GmbH) and Perfect Pupil (Milvella Pty Ld), to name just a few.

	In the past, I nearly always used iris hooks in patients with small pupils. However, for my difficult cases, including patients with intraoperative floppy iris syndrome and pseudoexfoliation syndrome, I now almost always use the Malyugin ring (MicroSurgical Technology, Inc.).

Related: How to reduce posterior capsular rupture

	The brainchild of Boris Malyugin, professor of ophthalmology and deputy director general at the S. Fyodorov Eye Microsurgery State Institution in Russia, the Malyugin ring was designed to overcome some of the disadvantages associated with other pupil expanders, such as overstretching of the iris sphincter and extended surgery time. The Malyugin ring is a square-shaped device made from 5/0 polypropylene with a paperclip-scroll design that holds the iris at eight equidistant points.

	The result is a round pupil, rather than the square one formed with four iris hooks, and circumferential protection of the iris (Figure 1). Helpfully, the device is available in two sizes, 6.25 mm and 7.00 mm, which offers a degree of flexibility. For example, while the 6.25 mm ring is suitable for most cases, the 7.00 mm ring is more suitable when placing an IOL with a large-diameter optic, or for surgeons who use the divide-and-conquer technique.

	As noted earlier, I used to employ iris hooks during cataract surgery in patients with small pupils. In doing so, it was necessary for me to create four or five corneal incisions.

	Although I never experienced any problems with hooks, there is the risk that they might overstretch the iris sphincter and create iris defects. The main advantage of the Malyugin ring is that it can be inserted via the main clear corneal incision, eliminating the need for multiple incisions.

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	There is no need to widen the main incision. I use a 2.2 mm incision and can easily place the Malyugin ring through it. This obviously saves considerable surgical time and is less invasive than using iris hooks.

	The Malyugin ring also eliminates stretching or distorting of the pupil. Because it affords minimal contact with the iris, it is less likely to damage the iris sphincter than other rings or hooks. Perhaps not surprisingly, I no longer turn to hooks when I need to perform mechanical pupil expansion.

	The Malyugin ring is very easy to use thanks to its disposable injector, which aids placement of the ring around the edge of the pupil. Typically, the first three of the four paperclip-like scrolls are very easy to insert.

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	However, to facilitate insertion of the fourth scroll close to the main incision, I would advise using the injector and an Osher micromanipulator (MicroSurgical Technology, Redmond, WA), which is designed for the specific geometry of the Malyugin ring, through a second incision.

	After surgery, the same Osher micromanipulator can be used to remove the twelve o’clock scroll, while the injector can be used to quickly and smoothly remove the ring without trauma to the iris sphincter (Figure 2). Unlike other pupil-expansion devices, the injector can be disposed of once surgery is complete, eliminating the need for sterilisation and its associated costs.

	Of course, I also use other pupil expanders and hooks, although perhaps less frequently than the Malyugin ring.

 Laboratories, Inc., Fort Worth, TX) are useful in specific cases where I need to open the iris locally rather than globally. In cases of traumatic damage, some local pupillary defect or iris desinsertion may happen and iris hooks help ensure safer cataract surgery.

Related: Managing dislocated IOLs with scleral suture fixation

	Thankfully, small pupils are not very common so, for most surgeons, the need for hooks and mechanical dilators such as the Malyugin ring is somewhat limited.

	However, to date and in my experience, the use of the Malyugin ring appears to be safe without any intraoperative difficulties or complications observed.

	It undoubtedly provides greater confidence to the surgeon in offering safer and more effective cataract surgery to patients with small pupils.

	Cedric Schweitzer, MD, is an ophthalmologist based at the University Hospital Bordeaux in France. Dr Schweitzer has no financial interests in MicroSurgical Technology, Inc.

Cataract patients with small pupils present a particular challenge for surgeons. Using a pupil expansion device such as the Malyugin ring may help to reduce the complications associated with small pupil cataract surgery.

Author | Cedric Schweitzer, MD

Articles

Femtosecond lasers and phacoemulsification go head to head in French trial

Managing complications using the Malyugin ring

Clinical experience with a mechanical pupil dilator