Outcomes of 27 Gauge Microincision Vitrectomy Surgery for Posterior Segment Disease

In their study entitled “Outcomes of 27 Gauge Microincision Vitrectomy Surgery for Posterior Segment Disease,” Khan and associates present their initial experience with the 27 G microincision vitrectomy system (MIVS) in 95 eyes. The study is extremely valuable, as it includes the largest sample of patients operated with 27 G MIVS to date.

The current study evaluated intraocular pressure (IOP) and reports an initial fall in IOP over the first week, after which IOP started increasing again by day 30, although minimally. This result was nearly statistically significant ( P = .05) in the straight incision group and consistent with both types of incisions. A recently published study of patients operated with 20 G, 23 G, and 25 G vitrectomy systems found mean IOP to decrease from the baseline over a period of 3 months, followed by a steady increase toward baseline value until a follow-up of 2 years. Hence, it appears that IOP increases at a faster rate toward baseline value with a smaller gauge of MIVS. The 0.4 mm sclerotomy of the 27 G system is expected to become water-tight quickly vis-à-vis the conventional vitrectomy systems. However, the overall mean IOP in the current study remained low at 3 months. The ambiguity between day 30 and day 90 results can be resolved by evaluating IOP at day 90 in both the incision groups separately, as has been done for other follow-up visits.

Movement of viscous fluid through smaller-gauge cannulas is slow, and 25 G MIVS has previously been evaluated for removal of silicone oil in this regard too. It is heartening to note that converting to hybrid vitrectomy was not needed for such cases in this series. However, 3 silicone oil–filled eyes eventually needed sutures for closing a single sclerotomy site at the end of the surgery. The authors interpret this finding in terms of the type of 27 G scleral incision used. As only 1 sclerotomy needed sutures for adequate wound closure in these 3 cases, the need for suture-assisted wound closure is more likely to be linked to the excessive sclerotomy site manipulation involved owing to the complexity of the cases, as evidenced by the need for injecting silicone oil. Nearly half of the silicone oil–filled eyes needed wound suturing. During vitrectomy, it is second nature for the surgeon to hinge the eye with the cutter or the illuminator at the sclerotomy site and rotate it for adequate visualization of peripheral retinal areas. Such forceful manipulations can make sclerotomy margins irregular; hence, the lack of self-sealing. Also, with the advent of more rigid probes to prevent bending during surgery, such sclerotomy site changes may be more profound in the future.

The 27 G MIVS is an evolving modality for retinal surgery, and such observations would add to its validation as the upcoming system of choice for vitrectomy.

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Jan 6, 2017 | Posted by in OPHTHALMOLOGY | Comments Off on Outcomes of 27 Gauge Microincision Vitrectomy Surgery for Posterior Segment Disease

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