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Retained subretinal perfluorocarbon more prevalent with smaller-gauge vitrectomy
Study advocates 23-gauge valved instrumentation to reduce incidence.
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Patients undergoing rhegmatogenous retinal detachment repair were four times more likely to have retained subretinal perfluorocarbon liquid with sutureless microincision 23-gauge vitrectomy than with traditional sutured 20-gauge instrumentation, according to a study.
However, only one eye from each of the two separate gauge groups was found to be visually affected by retention of perfluorocarbon liquid (PFCL), for which follow-up surgery proved unsuccessful.
“After transitioning from traditional 20-gauge vitrectomy to 23-gauge vitrectomy, it appeared to me that there was an increased incidence of subretinal perfluorocarbon liquid,” lead study author Sunir J. Garg, MD, told Ocular Surgery News. “Although small amounts of subretinal PFCL occasionally occur and usually are not visually significant, sometimes it would get under the fovea, which would cause visual impairment. Secondly, if the PFCL does get under the fovea, it can be very challenging to remove.”
The retrospective review was published in Retina.
Study
Garg performed all 234 retinal detachment repairs over a 3-year period. During postoperative visits, subretinal PFCL was detected in four of 176 eyes (2.3%) that underwent 20-gauge pars plana vitrectomy as opposed to six of 58 eyes (10.3%) that underwent 23-gauge pars plana vitrectomy.
“Although microincision vitrectomy is a great advance, with any new technology comes subtle changes that we might not appreciate or realize,” Garg said. “I expected there might be a slightly higher rate of subretinal PFCL with 23-gauge vitrectomy, but not a 4.5-fold increase.”
Sunir J. Garg
Conceptually, the 20-gauge vitrectomy would create a more stable system, Garg said.
Other than one case of retained subretinal PFCL in each of the two groups, the retained PFCL cases were not found to be visually significant and did not require additional surgery, Garg said.
For the remaining two eyes, the PFCL went beneath the fovea and was believed to be visually significant. A second surgery to remove the subretinal PFCL did not improve the patients’ vision, he said.
Minimizing turbulence
“When we started using 23-gauge instrumentation, even though the incisions and openings were smaller, the openings were round and patent and thus allowed much greater fluid flow in and out of the eye. This created more turbulence than we generally saw with 20-gauge vitrectomy,” Garg said. “Even though the wounds were ‘larger’ with 20-gauge, they were slit openings, so they actually would sort of close by themselves, acting like valves, and would not allow as much fluid to flow through the eye. This caused less turbulence, which reduced disruption of the PFCL, leading to less subretinal PFCL.”
Reducing turbulence within the eye is the critical part of primary surgery. Garg has begun using valved 23-gauge cannulas, which create less turbulence, he said.
Two other options for decreasing turbulence are reducing the infusion pressure when using non-valved cannulas and clamping the infusion line when removing instruments from the eye.
A follow-up study using valved 23-gauge cannulas is currently under way.
“I expect the valved cannulas to cause less subretinal PFCL than the traditional 23-gauge cannulas, thus supporting the hypothesis that less fluid flow in and out of the eye will lead to less PFCL going underneath the retina,” he said. “I anticipate the incidence rate to be comparable to the results we have seen with 20-gauge vitrectomy.” – by Bob Kronemyer