Futuristic surgical tools competing

Vitrectomy Showdown: Small-Gauge vs. 20-Gauge - Which Comes Out on Top?

Theo Raines in Health & Wellness December 2025 • 3 min read.

"A deep dive into the evolving world of endophthalmitis treatment: Comparing the outcomes and culture-positive rates of small-gauge and 20-gauge vitrectomy."

Endophthalmitis, a severe intraocular inflammatory condition, poses a significant threat to vision. Vitrectomy, particularly pars plana vitrectomy (PPV), has become a cornerstone in managing these advanced cases. PPV helps remove infecting organisms and toxins, clears vision-obstructing opacities, and enables the delivery of antibiotics.

Since the Endophthalmitis Vitrectomy Study (EVS), surgical techniques have seen remarkable advancements, notably the rise of smaller-gauge instruments (23- and 25-gauge) for PPV. Unlike the 20-gauge approach, small-gauge surgery involves creating self-sealing sclerotomies without conjunctival dissection, often using cannulas, which translates to less surgical trauma and quicker recovery.

While small-gauge vitrectomy has become increasingly popular, questions remain about its efficacy compared to the traditional 20-gauge method, especially in endophthalmitis cases. One concern is whether the smaller instrument size and increased cutting speeds might affect the viability of microbiological specimens collected during the procedure.

Decoding the Study: Comparing Visual Outcomes and Culture Positivity

A retrospective study at the University of Iowa compared the outcomes of patients undergoing vitrectomy for endophthalmitis using small-gauge (23- and 25-gauge) versus 20-gauge instrumentation. The study spanned ten years, analyzing visual outcomes, culture-positive rates, and etiological trends.

The results revealed that final visual outcomes were similar between the two groups. However, a significant difference emerged in culture-positive rates. The 20-gauge group showed a higher culture positivity rate (74.1%) compared to the small-gauge group (35.3%).

Here are some key takeaways from the research:

Visual outcomes comparable: Both small-gauge and 20-gauge vitrectomy provide similar final vision results.
Culture positivity difference: Small-gauge vitrectomy had significantly lower culture-positive rates compared to 20-gauge.
Etiological shift: Increasing cases of endophthalmitis linked to intravitreal injections, particularly in the small-gauge group.
In vitro findings: Lab tests found no significant impact of vitrector gauge or cutting speed on bacterial culture growth.

To explore the reasons behind the culture positivity difference, the researchers conducted in vitro laboratory testing. This testing examined the impact of vitrector lumen size and cutting speed on the ability to culture bacteria. Surprisingly, the in vitro results showed no significant difference in bacterial culture growth related to either vitrector gauge or cutting speeds.

The Evolving Landscape of Endophthalmitis Management

While small-gauge vitrectomy offers comparable visual outcomes to the 20-gauge approach, the difference in culture-positive rates warrants further investigation. The rise in endophthalmitis cases linked to intravitreal injections highlights the evolving nature of this condition. As intravitreal injections become more common, understanding and addressing the associated risks will be crucial.

About this Article -

This article was crafted using a human-AI hybrid and collaborative approach. AI assisted our team with initial drafting, research insights, identifying key questions, and image generation. Our human editors guided topic selection, defined the angle, structured the content, ensured factual accuracy and relevance, refined the tone, and conducted thorough editing to deliver helpful, high-quality information.See our About page for more information.

This article is based on research published under:

DOI-LINK: 10.2147/opth.s95906, Alternate LINK

Title: Comparison Of Microbiology And Visual Outcomes Of Patients Undergoing Small-Gauge And 20-Gauge Vitrectomy For Endophthalmitis

Subject: Ophthalmology

Journal: Clinical Ophthalmology

Publisher: Informa UK Limited

Authors: Vinit Mahajan, David Almeida, Eric Chin, Shaival Shah, Benjamin Bakall, Karen Gehrs, Culver Boldt, Stephen Russell, James Folk

Published: 2016-01-01

Everything You Need To Know

What is the role of pars plana vitrectomy (PPV) in the treatment of endophthalmitis, and how has it evolved since the Endophthalmitis Vitrectomy Study (EVS)?

Pars plana vitrectomy (PPV) is a surgical procedure that has become essential in treating endophthalmitis. It works by removing infecting organisms and toxins, clearing opacities that obstruct vision, and facilitating the delivery of antibiotics directly into the eye. The Endophthalmitis Vitrectomy Study (EVS) highlighted the importance of vitrectomy. While the EVS provided a foundation, advancements in surgical techniques have led to the development of smaller-gauge instruments, improving the approach to managing this severe condition.

In the University of Iowa study, what significant difference was observed between small-gauge vitrectomy and 20-gauge vitrectomy concerning culture positivity rates, and what could explain this difference?

A key difference observed in the study was the culture positivity rate. The 20-gauge vitrectomy showed a significantly higher culture-positive rate (74.1%) compared to the small-gauge vitrectomy (35.3%). While in vitro testing didn't reveal a direct impact of vitrector gauge or cutting speed on bacterial culture growth, this difference suggests there may be other factors affecting the ability to detect the causative organisms when using smaller-gauge instruments. These factors could include differences in sample collection techniques or the volume of sample obtained.

How does small-gauge vitrectomy differ from the traditional 20-gauge approach, and what are the potential advantages of using smaller-gauge instruments in pars plana vitrectomy (PPV)?

Small-gauge vitrectomy involves using 23- or 25-gauge instruments to perform pars plana vitrectomy (PPV). Unlike the traditional 20-gauge approach, small-gauge surgery creates self-sealing sclerotomies without needing conjunctival dissection. This is often achieved using cannulas. The perceived advantages of small-gauge vitrectomy include reduced surgical trauma, quicker recovery times for patients, and potentially fewer postoperative complications, making it an appealing alternative to the 20-gauge method. However, considerations about culture positivity rates need attention.

In the treatment of endophthalmitis, how do the final visual outcomes of small-gauge vitrectomy compare to those of the traditional 20-gauge method?

The study revealed that final visual outcomes were comparable between small-gauge (23- and 25-gauge) vitrectomy and 20-gauge vitrectomy when used to treat endophthalmitis. This suggests that both approaches can be effective in restoring or preserving vision in patients with this condition. However, while visual outcomes were similar, differences in other factors, such as culture positivity rates, highlight the need for careful consideration when choosing a surgical technique.

Why is the increasing incidence of endophthalmitis cases linked to intravitreal injections a significant concern, and what implications does this trend have for the management of the condition?

The increasing number of endophthalmitis cases linked to intravitreal injections is significant because it points to an evolving etiological trend. As intravitreal injections become more prevalent in treating various retinal conditions, the risk of injection-related endophthalmitis also rises. This shift underscores the importance of stringent sterile techniques during injections, as well as the need for heightened awareness and proactive measures to prevent and manage this complication, especially in the context of small-gauge vitrectomy where culture positivity rates may be lower.