Dr Boris Malyugin highlights strategies for tackling small pupils
Performing cataract surgery on an eye with a small pupil remains technically challenging, but with the right tools and a clear strategy, the surgery can usually be completed successfully with little risk of complications, said Boris Malyugin MD, PhD, in his Binkhorst Medal Lecture at the XXXV Congress of the ESCRS in Lisbon.
Boris Malyugin MD, PhD
In a wide-ranging lecture that focused on the challenge of cataract surgery in high-risk eyes, Dr Malyugin, Professor of Ophthalmology and Deputy Director General at the S. Fyodorov Eye Microsurgery Federal State Institution in Moscow, Russia, paid tribute to predecessors such as Cornelius Binkhorst, whose work was instrumental in the development of intraocular lenses, and Svyatoslav Fyodorov, who designed the “Sputnik” pupil-fixated IOL.
Turning to the question of high-risk eyes in cataract surgery, Dr Malyugin said that surgeons dealt with such cases every day.
“The definition of high-risk eyes is very broad. Patients with local and/or systemic comorbidity, abnormal eye global anatomy, compromised capsules, increased lens hardness, zonular weakness and small pupils all come into this category,” he said.
Small pupils pose a significant challenge even for skilled and experienced surgeons, and should not be taken lightly.
“Poor mydriasis is not purely a geometrical issue and a question of accessing the lens – it is a lot more complex than that. A small pupil is an indicator of underlying pathologies within the eye, and is usually associated with systemic or local comorbidities, including but not limited to pseudoexfoliation syndrome, zonular weakness, blood-aqueous barrier disruption, and intraocular pressure spikes,” he said.
Small pupils are also associated with an increased risk of complications such as iris trauma, capsular rupture, vitreous loss, inflammation, incomplete evacuation of the cortical material, and difficulties with placing and aligning the IOL in the bag, he added.
“It was shown that every millimetre of pupil constriction increases our complication rate by 10%,” said Dr Malyugin.
For many years, the standard pharmacological approach to small pupils was to use topical mydriatic agents, said Dr Malyugin, while more recently phenylephrine injections into the anterior chamber have become popular.
While these compounds serve well for many patients, the pharmacological approach does not work all the time and may lead to unwanted ocular and systemic side-effects. Alternative strategies will be required to complete the surgery successfully in such cases, he said.
If the intracameral injection does not provide sufficient mydriasis, one strategy is to proceed with viscodilation, posterior synechiolysis and pupil-stretching techniques, if appropriate, said Dr Malyugin.
Dissecting posterior synechiae will invariably improve mydriasis, and surgeons may also consider using mechanical expansion devices such as iris hooks or pupil rings.
Phacoemulsification is manageable in small pupils for an experienced surgeon, said Dr Malyugin. “By decreasing fluidic parameters, using phaco chop technique, by holding the instruments at the very centre of the anterior chamber using appropriate viscoelastic it is possible to avoid iris damage and complete surgery even with a constricted pupil of 4mm or even sometimes less in diameter,” he said.
Iris hooks are effective at stretching the pupil, but they do have some significant drawbacks, said Dr Malyugin.
“Iris hooks require multiple incisions and tend to overextend the pupil more than necessary. This can lead to damage to the iris tissue and to postoperative complications such as atonic pupil,” he said. “My personal preference,” Dr Malyugin said, “are the capsule hooks because they allow the surgeon not only to expand the pupil but also to stabilise the capsular bag in patients with compromised zonules.”
Early in his surgical career, it was the frustration of working with first-generation pupil expansion rings that prompted Dr Malyugin to try to improve on those initial designs.
“These early expansion rings were not easy to work with and they could lead to complications with the surgery,” he said.
This provided the initial inspiration for the Malyugin Ring (MicroSurgical Technology), a pupil expansion ring that would be easier to inject and position within the eye and that could be implanted with minimal trauma and removed through micro-incision.
The Malyugin Ring consists of a pre-sterilised single-use holder containing the ring and inserter and comes in two sizes: 6.25mm and 7.0mm. The second-generation version of the ring became available last year, said Dr Malyugin. Made from 5-0 polypropylene and implanted through a 2.0mm incision, the new ring is more flexible and gentler to the iris, and comes with a redesigned inserter that can easily fit through a 2mm clear corneal incision.
“I still use the older versions of the ring for irises that are very fibrotic. In these cases I need a bit more force to expand the pupil. However, specifically for cases of intraoperative floppy iris syndrome (IFIS) the new ring works very well indeed,” he said.
The Malyugin Ring can be inserted through regular incisions, as well as through the smaller microincisions used in MICS with a wound-assisted technique of insertion and removal. The device also works well in femtosecond-assisted cataract surgery, he said.
These advantages and solid clinical results from the first trials of the device spurred phenomenal demand for the Malyugin Ring, with more than 1 million of the devices used in cataract patients since its introduction a decade ago.
Boris Malyugin: firstname.lastname@example.org