Minimally invasive vitreo retinal surgery: how small do we go?

The armamentarium of vitreo retinal surgeons has advanced tremendously with advances in physics and now the focus is on the maximum benefit that can be derived using micro incisions.

The 23-G and 25-G systems have become fairly common and several studies have been done to determine the safety, advantages and disadvantages of small gauge sutureless surgery.[1] Though higher infusion and aspiration pressures are needed to remove the vitreous using small gauge probes, the corresponding damage on tissues is also substantially lower.

My own experience with the small gauge vitrectomy system encouraged me to embrace this advancement in totality. My experience shows that the smaller gauge vitrectomy techniques shorten operating time and improve patient comfort. By minimizing surgically induced trauma, it decreases the post-operative inflammatory response and hastens recovery. Although higher pressures are needed for injection of silicon oil especially the heavy oil, the overall outcomes are much better. Various surgical procedures have been performed with microincision vitrectomy surgery (MIVS) but it is being advocated for macular holes and epiretinal membrane (ERM) surgery. Sandali et al. in their study[2] concluded that in ERM surgery 23-G and 25-G systems are as safe and effective as the 20-G system. They also noted that MIVS systems cause significant reduction in surgical time. Similar results have been reported by Haas et al.[3] I prefer a proportional mode vitrectomy for the separation of the membrane from the retina and it has given me excellent results.

Concerns have been raised about the increased risk of endophthalmitis with 23-G and 25-G instrumentation. Oshima et al. in their study Multicenter survey with a systematic overview of acute-onset endophthalmitis after transconjunctival MIVS[4] found no significant difference in the incidence of post vitrectomy endophthalmitis between MIVS and 20-G vitrectomy similar results were observed by Bahrani et al.[5] Our experience is also similar as there have been no differences between the 20-G and MIVS in incidence of post-operative endophthalmitis. Nevertheless, the microsurgical task force came up with guidelines for minimizing endophthalmitis with vitrectomy surgery.[6]

The advent of the 27-G instrument system, has given a totally new dimension to microsurgery.[7] For obvious reasons the fluid dynamics of the 27-G system are lower than 25-G MIVS. The pros and cons of the small gauge system will have to be weighed to decide how small we can go. The desired goal of surgery is to achieve optimal surgical results with minimal damage. Optimal utilization of the newer properties of machines in relation to the characteristics of the disease will have to be assessed to decide the risk benefit ratio of the MIVS system.[8] The risk of instrument bending, leading to lower stability and reduced cutting efficiency is a point for concern. This needs to be compared with improved wound healing and finer surgical results in select cases. I look at the future where further advances in technology will obviate the risks associated with the smaller gauge.