27-gauge Vitrectomy Wound Integrity: a Prospective, Randomized Trial Comparing Angled Versus Straight Entry

Microincision vitrectomy surgery (MIVS) has largely replaced use of conventional, 20-gauge vitrectomy, offering more rapid visual recovery, decreased postoperative pain and inflammation, and reduced surgical time with use of smaller diameter instruments1. Most recently, 27 gauge vitrectomy instrumentation has been introduced2, offering an additional small gauge option to the currently available 23, 25, or 25+ gauge systems.

Initial experience with small gauge MIVS yielded mixed results, with early reports noting increased rates of wound-related postoperative complications including hypotony, choroidal detachments, endophthalmitis, and sclerotomy-related retinal tears3,4. However, with more experience and instrument modifications, outcomes with MIVS improved1,3. In a 2010 Ophthalmic Technology Assessment report by the American Academy of Ophthalmology, outcomes of MIVS were found comparable to that of 20 gauge vitrectomy benchmarks5.

Prior studies have established that a two-stage, angled incision results in improved wound integrity with 23, 25, and 25+ MIVS systems6,7, helping to prevent complications such as post-operative endophthalmitis and hypotony. However, in the two clinical series describing outcomes of 27 gauge MIVS, a one-stage, perpendicular wound construction was performed without complication in a series of 31 patients2,8. Thus far, direct comparison between wound construction techniques (one-stage, perpendicular or two-stage, angled) has not been evaluated.

The purpose of this study is to prospectively compare clinical outcomes using straight, one-stage (perpendicular) versus angled, two-stage trocar insertion during 27 gauge minimally invasive vitrectomy surgery (MIVS). The design of the study will be a randomized, clinical trial. Primary outcomes will be sclerotomy suture rates and incidence of suture blebs at the end of 27 gauge MIVS surgery for epiretinal membrane and macular pucker indications (no air or gas tamponade). Secondary endpoints will include rate of postoperative wound-related complications such as hypotony, choroidal detachments, endophthalmitis, and sclerotomy-related retinal tears with a minimum of 30 days follow-up.

Inclusion criteria

• Patients older than 18 years old undergoing 27 gauge vitrectomy surgery with membrane peel for epiretinal membrane
• Willing and able to comply with clinic visits and study-related procedures
• Provide signed informed consent

Exclusion criteria

• History of previous vitrectomy surgery in the study eye.
• History of previous ocular surgery other than cataract extraction in the study eye.
• Requirement of an air or gas (SF6, C3F8) bubble at the conclusion of 27 gauge MIVS surgery.
• Aphakia, ACIOL, unstable PCIOL, and/or lenticular or zonular instability.
• Glaucoma requiring IOP lowering medications.
• Pre-existing ocular inflammation/uveitis.
• Any concurrent intraocular condition in the study eye that, in the opinion of the investigator, could either require medical or surgical intervention during the 12 week study period to prevent or treat visual loss that might result from that condition. Examples include infectious conjunctivitis, keratitis, and/or scleritis.