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IOL insertion speed affects wound size
Slower insertion may cause a greater need for corneal hydration and more changes seen on OCT.
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Fast is better than slow when inserting an IOL using a screw-plunger injector cartridge system, according to a study.
“Every time I performed IOL surgery, I thought that the IOL could be inserted through an extra-small incision and with a higher success rate when I rotated the plunger at a faster speed,” study author Masayuki Ouchi, MD, PhD, chairman of the Ouchi Eye Clinic in Kyoto, Japan, told Ocular Surgery News.
“I found a smaller postoperative wound in fast IOL insertion eyes as opposed to moderate speed eyes. I wanted to present a study constructed of both clinical data and laboratory examination of the cartridges. The lab results would provide the reason for the clinical outcomes,” he said.
The study was published in the Journal of Cataract and Refractive Surgery.
Study method
The prospective, randomized clinical trial included 80 eyes undergoing phacoemulsification and implantation of an AcrySof IQ lens (Alcon). Fast IOL insertion at a plunger speed of 1 revolution per second (rps) was performed in 40 eyes, while the other 40 eyes underwent slow IOL insertion at 0.25 rps.
The mean change in clear corneal wound size from before insertion to after insertion in the fast-insertion group was 0.0028 mm, compared to 0.097 mm in the slow-insertion group (P = .002).
Requiring corneal hydration to seal the wound was more likely in the slow-insertion group: 52.5% (21 of 40 eyes) vs. 27.5% (11 of 40 eyes) in the fast-insertion group (P = .04).
Greater changes were seen on anterior segment optical coherence tomography scan of the corneal incision at 1 day postop in the slow-insertion group and included endothelial gap, crack or bulge.
“All these findings correspond with my own impressions from my own surgery,” said Ouchi, who performed all surgeries for the study. “However, I detected no significant differences in surgically induced astigmatism or changes in corneal refractive power among the two groups.”
Follow-up
After compiling his clinical data, Ouchi evaluated five injector cartridges — Monarch III screw plunger-type injectors (Alcon) attached with a D cartridge — for changes in measurement of the cross-sectional surface between empty cartridges and those with an IOL loaded inside.
“I thought this might be helpful for understanding the mechanism of my clinical findings,” Ouchi said. “All the injector cartridges expanded vertically, although not horizontally, when an IOL passed through the cartridge. Of course, surgical incisions are made horizontal in general. This means that all surgical wounds receive vertical stress during IOL insertion. Therefore, it is clear that IOL insertion time should be as quick as possible to lessen wound stress.”
However, Ouchi said that surgeons should be cautious of the quick-insertion method because of the potential for “explosion” and for inducing tissue injury, particularly when using a wound-assisted technique.
An electric injector that pushes the IOL at a constant speed, independent of the resisting force, is currently under development, according to Ouchi.
“Someday, we might be able to set an even higher-speed installation,” he said.
Meanwhile, surgeons should calculate the degree of surgical intervention when performing the procedure in vivo with an emphasis on the surgical wound, rather than concentrating solely on complication rates and postop exams for safety and efficacy, Ouchi said. – by Bob Kronemyer
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Amar Agarwal, MS, FRCS, FRCOphth
This is a very good paper to compare incision and IOL injection. One of the problems in cataract surgery is wound integrity, and we tend to forget this when we are implanting the IOL. Wound-assisted injection of an IOL can help pass the IOL through a smaller incision, but does it affect wound integrity? Also the speed at which the IOL is injected can make a difference to wound architecture. It is important for the surgeon to analyze this aspect in cataract surgery.
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