Performance Comparison of High-Speed Dual-Pneumatic Vitrectomy Cutters during Simulated Vitrectomy with Balanced Salt Solution

27‑Gauge vitrectomy vs. 25‑gauge vitrectomy in the management of proliferative diabetic retinopathy with preoperative intravitreal injection of conbercept

Small-gauge vitrectomy has become popular due to its notable advantages, including less trauma, shortened convalescence and improved manoeuvrability. The aim of the present study was to compare the surgical outcomes of 27-gauge (27-G) vitrectomy with those of 25-gauge (25-G) vitrectomy in the management of proliferative diabetic retinopathy (PDR) with preoperative intravitreal injection of conbercept. The data of 48 consecutive patients with PDR (48 eyes) were retrospectively collected. The patients underwent conbercept intravitreal injection and pars plana vitrectomy with a 27-G group (23 eyes) or 25-G group (25 eyes) vitrectomy system. The operating time, suturing rate, endodiathermy rate, postoperative best-corrected visual acuity (BCVA), intraocular pressure (IOP) and complications were recorded. The mean postoperative BCVA at final follow-up was significantly improved compared with that at the baseline in both groups (P<0.001 for both). The differences in the mean BCVA changes between the two groups were not significant (P>0.99), and no differences were observed in the final central foveal thickness (P=0.51) between the two groups. The final IOP remained stable compared with that at the baseline in the 27-G group (P=0.36) and the 25-G group (P=0.05). The suturing rate was significantly decreased in the 27-G group compared with the 25-G group (P=0.04). There were no significant differences between the two groups in terms of the operating time (P=0.18), rate of endodiathermy use (P>0.99), iatrogenic retinal breaks (P=0.42) or postoperative recurrent vitreous haemorrhage (P>0.99). In addition, no case of ocular hypotony was observed in either group. In conclusion, 27-G vitrectomy was as efficient and safe as 25-G vitrectomy in the management of PDR in terms of operating time and complications. With reference to the literature, preoperative conbercept injection appears to assist in decreasing the incidence of intraoperative and postoperative complications.

Performance, safety and efficiency comparison between 10,000 and 5000 cuts per minute vitrectomy using a 25G cutter: a prospective randomized controlled study

PURPOSE

This study aims to compare the performance of the 25+® UltraVit® 5000 cuts per minute (cpm) vitrectomy probe versus the 25+ ® Ultravit 10,000 cpm® beveled tip, dual drive vitrectomy probe.

METHOD

In this prospective randomised controlled clinical trial, 52 eyes of 52 consecutive patients were randomized into either the 10,000 cpm (25 patients) or 5000 cpm vitrectomy group (27 patients). Patients were evaluated preoperatively, intraoperatively, and postoperatively on the first day, and at 1 week, 1 month and 3 months. The main outcome measures were vitrectomy time, and secondary endpoints were time to induction of posterior vitreous detachment, intraoperative complications, and number of instruments used.

RESULTS

The vitrectomy time was shorter in the 10,000 cpm group (413.7 s) compared to the 5000 cpm group (463.4 s), although there was no significant difference (p = 0.5999). One patient had an iatrogenic retinal break in the 10,000 cpm group while two patients had an iatrogenic retinal break in the 5000 cpm group. The time for posterior vitreous detachment (PVD) induction and the number of instruments used were not significantly different between the two groups.

CONCLUSION

The difference in vitrectomy times between the 10,000 cpm vitrectomy probe and the 5000 cpm cutter were not statistically significant. This may suggest that other factors affect efficiency rather than the limitations of equipment.

FLUIDIC PERFORMANCE OF A DUAL-ACTION VITRECTOMY PROBE COMPARED WITH A SINGLE-ACTION PROBE

PURPOSE

To assess flow rates, nearfield effects, and traction of a dual-cutting 20,000 cpm vitrectomy probe (HYPERVIT, Alcon) versus a single-cutting 10,000 cpm probe (Advanced ULTRAVIT, Alcon).

METHODS

Flow rates were evaluated for 25+ and 27+ gauge probes using balanced salt solution or porcine cadaver vitreous (biased open, 50/50, and biased closed duty cycles). Probes were suspended in an open beaker, and flow rates were calculated using a precision balance. Nearfield effects and flow pulsatility were assessed using a validated simulation model based on experimental microparticle image velocimetry. Traction was assessed by attaching vitreous to a cantilever beam and measuring the deflection of the beam.

RESULTS

For HYPERVIT probes, aqueous flow rates were similar across all cutting rates. Vitreous flow rates increased with increasing cutting rates. At maximum cutting rates, aqueous flow was 62%-67% greater (25+) and 63% greater (27+) with HYPERVIT versus Advanced ULTRAVIT ( P < 0.05); vitreous flow was 44%-47% greater (25+) and 26%-32% greater (27+) with HYPERVIT versus Advanced ULTRAVIT ( P < 0.05). Nearfield effects were reduced, and peak traction forces were significantly lower for HYPERVIT versus Advanced ULTRAVIT ( P < 0.05).

CONCLUSION

Significantly greater aspiration flow, reduced nearfield effects, and reduced traction were observed with dual-action versus single-action probes.

Dynamic Pressure Measurements During Vitrectomy in a Model of the Eye

Purpose

To accurately evaluate pressure changes during vitrectomy in a rigid model of the vitreous chamber and to test the efficiency of the EVA phacovitrectomy system (Dutch Ophthalmic Research Center) in terms of compensation of intraocular pressure variations.

Methods

We tested 23-, 25-, and 27-gauge double-blade vitreous cutters in both vented global pressure control and automatic infusion compensation (AIC) modes in a vitreous chamber model, mimicking the real surgical procedure. Balanced salt solution and artificial vitreous, similar to the real vitreous body, were used. We tested both standard-flow (SF) and high-flow (HF) infusion systems, varying the infusion pressure between 20 and 40 mm Hg. In each experiment, flow rate was also measured.

Results

Pressure drop was rapidly and efficiently compensated when 23- and 25-gauge cutters were used in AIC mode, with infusion pressures ranging between 30 and 55 mm Hg. The 27-gauge cutter was less efficient in compensating pressure variations. Pressure fluctuations related to the high-frequency motion of the cutter blade were small compared to the overall pressure variations. The use of the HF infusion system resulted in larger flow rates and lower pressure changes compared to the SF infusion system.

Conclusions

Despite the rigid material of the model, the present pressure measurements are in line with previous studies performed on porcine eye. The use of AIC mode compensates intraoperative pressure drops efficiently, with both 23- and 25-gauge cutters. The HF infusion system is more efficient than the SF infusion system.

Translational Relevance

The AIC infusion mode efficiently compensates intraoperative pressure drops, in both 23- and 25-gauge experimental vitrectomy. The HF infusion system resulted in larger flow rate and lower pressure changes.

Comparisons of flow dynamics of dual-blade to single-blade beveled-tip vitreous cutters

INTRODUCTION

To compare the flow dynamics of the dual-blade to the single-blade beveled-tip vitreous cutters.

METHODS

The aspiration rates of balanced salt solution (BSS) and swine vitreous were measured for the 25-gauge and 27-gauge dual- and single-blade vitreous cutters. The flow dynamics of BSS and diluted vitreous mixed with fluorescent polymer at the maximal cutting rates and the reflux of BSS were measured in images obtained by a high-speed camera. The distal end of the cutter was defined as the head end.

RESULTS

The aspiration rates of BSS and vitreous by the 25- and 27-gauge dual-blade cutters were significantly higher than those of both single-blade cutters at the maximal cutting rate (all P≤0.01). The mean aspiration flow of BSS in front of the port from a lateral view was significantly faster for both dual-blade cutters than for both single-blade cutters (P=0.003, P=0.019). The angle of the mean flow of BSS of both dual-blade cutters was from the distal end (P<0.001, P<0.001) but that of the single blade-cutters was from the proximal end. The velocity and angle of the mean reflux flow of both types of cutters were not significantly different. The mean aspiration flow of diluted vitreous was significantly faster for 25-gauge dual-blade cutters with the angle more from the proximal end and 27-gauge dual-blade cutters more from the distal end than both single-blade cutters (P=0.018, P=0.048).

CONCLUSION

The dual-blade beveled-tip vitreous cutters improve the efficiency of the vitrectomy procedures and maintain the distal aspirating flow by the beveled-tip.

In Vitro Comparison of Various High-Speed Vitrectomy Machines Using Dual Blade Cutters

Objectives

The objective of this study is to compare various dual blade vitrectomy cutters for their efficiency in an in vitro setting.

Methods

In this in vitro experimental study, we compared various vitrectomy systems including EVA (Dutch Ophthalmic Research Center, Zuidland, The Netherlands), REVOLUTION (Optikon 2000, Inc., Rome, Italy), and OS4 (Oertli Instrumente AG, Berneck, Switzerland) in terms of efficiency in vitreous cutting and aspiration for various vitreous substitutes. These substitutes included water, chicken egg albumin, and goat vitreous. We only used 23-gauge dual blade cutters across all platforms to maintain uniformity. The cutting and aspiration efficiency was measured across various cut and vacuum settings of vitrectomy machines and measured as mass aspirated in a given time. Data analysis included comparing the amount of mass aspirated by these machines at preset cut and vacuum settings.

Results

Scatter plots showed a comparable mass of water aspirated by the EVA and REVOLUTION at 1000 to 5000 cuts per minute at a constant vacuum of 500 mm Hg whereas OS4 aspirated lesser mass at similar settings. Same trends were noted for goat vitreous for EVA and REVOLUTION but aspirated mass of albumin fluctuated widely across various platforms. At peak machine settings, REVOLUTION showed superiority across all three vitreous models due to its higher peak settings. The area under curve (AUC) analysis showed no significant differences among machines for water and goat vitreous at comparable settings but results were fluctuating for egg albumin.

Conclusion

Employing higher cut rates for dual blade cutters results in better efficiency of vitrectomy machines.

Comparison of modern high-speed vitrectomy systems and the advantages of using dual-bladed probes

Purpose

This study analyzes the efficiency of different vitrectomy systems and compares single with double-bladed cutters.

Methods

The systems EVA™ (DORC), Constellation^® Vision System (ALCON), megaTRON S4^HPS (Geuder) and Stellaris^® PC (Bausch and Lomb) were used. We chose 20G and 23G probes, since not all systems had switched to a smaller G at the time the study was conducted in 2016. Cut rates were varied in increments of 1000 cuts/min from 500 cpm to the system’s maximum and vacuum pressures were varied in increments of 100 mmHg, from 100 to 600 mmHg up to the individual system’s maximum. In this study water, egg white, Pluronic^®−F127 gel and isolated porcine vitreous were used as models of human vitreous. The vitrectomy efficiency was calculated from the aspirated mass (g) within 30 s. The aperture of the different vitrectomy probes was filmed with a high-speed camera.

Results

The area under the curve analysis showed differences in efficiency between vitrectomy systems. For water, a reverse relationship between the aspirated mass and cut rate was shown. By contrast, for most systems aspirated egg white and porcine vitreous showed a non-linear increase or decrease for 4000 cpm and above. For all vitreous surrogates, EVA™’s double-bladed probe aspirated significantly (p < 0.001) more vitreous than its mono-bladed probe. Video recordings showed less vitreous traction for double- in contrast to single-bladed probes.

Conclusion

We can demonstrate differences in the efficiency of vitrectomy depending on the vitrectomy system used. Double-bladed probes were more efficient and probably safer than single-bladed probes.

Simulation of Vitreous Traction Force and Flow Rate of High Speed Dual-Pneumatic 7500 Cuts Per Minute Vitrectomy Probes

Purpose

To develop methods to simulate vitreous flow and traction during vitrectomy and qualify these methods using laboratory measurements.

Methods

Medium viscosity and phase treatment were adjusted to represent vitreous (Eulerian two-phase flow) or saline solution (single-phase Navier-Stokes flow). Retinal traction was approximated using a one-way fluid-structure interaction simulating cut vitreous volume coupled to a structural simulation of elastic stretching of a cylinder representing vitreous fibers entrained in the flow.

Results

Simulated saline solution flow decreased, but vitreous flow increased with increasing cut rate, consistent with experimental trends observed for the 50/50 duty cycle mode. Traction simulations reproduced all trends in variation of traction force with changes in conditions. Simulations reproduced the majority of traction measurements within experimental error.

Conclusions

A scientific basis is provided for understanding how flow and traction vary with operational parameters. This model-based analysis serves as a “virtual lab” to determine optimal system settings to maximize flow efficiency while reducing traction.

Translational Relevance

The model provides a better understanding regarding how instrument settings can help control a vitrectomy procedure so that it can be made as efficient as possible (maximizing the rate of vitreous removal) while at the same time being made as safe as possible (minimizing retinal traction).

INCIDENCE OF ENDOPHTHALMITIS AFTER VITRECTOMY: A Systematic Review and Meta-analysis

PURPOSE

The purpose of this study was to review the literature reporting rates of postoperative endophthalmitis after pars plana vitrectomy and investigate whether modern microincision vitrectomy surgery (MIVS) increases the postoperative endophthalmitis rate, compared with traditional 20-gauge (20 G) vitrectomy.

METHODS

A comprehensive literature search was performed to identify studies describing the incidence of post-pars plana vitrectomy endophthalmitis. A meta-analysis of comparative studies reporting the endophthalmitis rates after MIVS versus 20 G vitrectomy was also conducted.

RESULTS

A total of 31 studies reported 199 endophthalmitis cases in 363,544 participants (0.05%). The incidence of endophthalmitis after 20 G vitrectomy was 0.04% (88/229,435), compared with 0.03% (8/27,326) after 23 G and 0.11% (33/29,676) after 25 G. The meta-analysis demonstrated that the incidence of endophthalmitis was higher after MIVS (23 G/25 G) compared with 20 G vitrectomy (odds ratio = 3.39, 95% confidence interval, 1.39-8.23). In a subgroup analysis, we also found an increased risk of endophthalmitis after 25 G compared with 20 G vitrectomy (odds ratio = 4.09, 95% confidence interval, 2.33-7.18), but not for 23 G versus 20 G (odds ratio = 1.14, 95% confidence interval, 0.47-2.78).

CONCLUSION

The incidence of post-pars plana vitrectomy endophthalmitis was low, with no significant differences between 23 G MIVS and 20 G vitrectomy, but 25 G MIVS may result in a higher postoperative endophthalmitis rate.

Clinical comparison of 27-gauge and 23-gauge instruments on the outcomes of pars plana vitrectomy surgery for the treatment of vitreoretinal diseases

PURPOSE OF REVIEW

To compare outcomes of 27-gauge and 23-gauge pars plana vitrectomy (PPV) for treatment of vitreoretinal diseases.

RECENT FINDINGS

Sixty-eight patients undergoing microincisional PPV for treatment of vitreoretinal diseases were randomized 1 : 1 to 27-gauge or 23-gauge surgery with a 7500 cuts-per-minute vitrectomy probe. The most common reasons for vitrectomy were epiretinal membrane (49%) and vitreous hemorrhage (24%). Mean ± standard deviation (SD) changes from immediate preoperative to immediate postoperative intraocular pressure were -0.40 ± 6.60 mmHg in the 27-gauge and -3.05 ± 7.64 mmHg in the 23-gauge group (adjusted mean difference 2.42 mmHg, 95% lower confidence limit 0.64, P = 0.013), but these changes were not associated with primary reason for vitrectomy (P = 0.065). Mean ± SD conjunctival edema grades in the 27-gauge and 23-gauge groups 1 week after surgery were 0.02 ± 0.124 and 0.10 ± 0.246, respectively (least squares mean difference -0.09, 95% upper confidence limit -0.03, P = 0.004), and were 0.01 ± 0.122 and 0.12 ± 0.338, respectively, at the probe incision site. Conjunctival edema grades were similar in both groups at 1 and 3 months. Mean ± SD pain ratings on postoperative day 1 - an indicator of patient comfort - were similar in the two groups.

SUMMARY

Smaller diameter vitrectomy instruments are associated with smaller reductions in immediate postoperative intraocular pressure.

Efficacy and safety of primary posterior capsulotomy in combined phaco-vitrectomy in rhegmatogenous retinal detachment

OBJECTIVE

To evaluate the efficacy and safety of posterior capsulotomy by analyzing the long-term visual outcomes in patients with rhegmatogenous retinal detachment (RD), who underwent combined phaco-vitrectomy with or without primary posterior capsulotomy.

METHODS

A retrospective longitudinal cohort analysis was performed by using data of rhegmatogenous RD patients undergoing combined phaco-vitrectomy. Patients were divided into two groups; Group A (68 eyes of 68 patients) with capsulotomy, and Group B (39 eyes of 39 patients) without capsulotomy. We reviewed the best-corrected visual acuity (BCVA), incidence of posterior capsule opacification (PCO), clinical features at the diagnosis of rhegmatogenous RD, and intraoperative or postoperative complications following posterior capsulotomy.

RESULTS

The modified BCVA measured by the logarithm of the minimum angle of resolution at initial diagnosis and 3, 6, and 12 months after surgery was 0.67 in Group A versus 0.85 in Group B (p = 0.258), 0.40 in Group A versus 0.50 in Group B (p = 0.309), 0.27 in Group A versus 0.45 in Group B (p = 0.055), and 0.21 in Group A versus 0.47 in Group B (p = 0.014), respectively. In subgroup with macula-on RRD, Group A exhibited better visual outcomes compared to Group B at 6(0.17 versus 0.40 [p = 0.037]) and at 12 months(0.14 versus 0.39 [p = 0.030]). The incidence of PCO in Group B was higher than Group A(28.2% versus 4.4% (p < 0.001)). There were no complications associated with posterior capsulotomy.

CONCLUSIONS

A primary posterior capsulotomy during combined phaco-vitrectomy using a 23-gauge vitreous cutter was a safe and effective surgical procedure in patients with RRD patients for preventing postoperative intraocular lens-related PCO.

Five-year nationwide incidence of macular hole requiring surgery in Korea

Background/aims

To estimate the incidence and demographics of macular hole (MH) requiring surgery in Korea.

Methods

Patients who underwent surgery for MH in Korea from 2011 to 2015 with the diagnostic code for MH and the surgical code for vitrectomy were retrospectively identified using the Korean national health claims database. The average incidence rate of MH during the 5-year study period was estimated by applying the direct method of standardisation using the 2015 census data as a reference population.

Results

A total of 7301 patients with MH requiring surgery were identified. The average incidence of MH requiring surgery was 3.14 (95 % CI, 3.07 to 3.21) per 100 000 person-years . The incidence in women (4.29 per 100 000 person-years; 95% CI, 4.17 to 4.40) was significantly higher than that in men (2.00 per 100 000 person-years; 95% CI, 1.92 to 2.07; p<0.001). The incidence rate of MH increased exponentially with increasing age between the ages of 35 years and 69 years and was highest among patients aged 65–69 years. The female-to-male ratio for the incidence of MH was 2.15:1.

Conclusions

This study represents the largest nationwide population-based investigation of the incidence of MH, using a database that covers the entire population of South Korea. MH is the disease of elderly peaked 70 years old and more common in women.

Fluidics of Single and Double Blade Guillotine Vitrectomy Probes in Balanced Salt Solution and Artificial Vitreous

PURPOSE

To assess the fluidics of double-vitreous cutter blade (DB) compared with single-blade (SB) guillotine with 23-, 25-, and 27-gauge vitrectomy probes. To assess flow characteristics and flow rates in viscous and viscoelastic fluids.

METHODS

We used Particle Image Velocimetry to measure the flow field close to the tip of each cutter probe and we derived kinematic quantities of interest, such as kinetic energy and acceleration. We performed measurements both on a balanced salt solution (BSS) and on a viscoelastic artificial vitreous (AV).

RESULTS

The flow rate is significantly higher with DB than SB vitrectomy probes, for a given pumping pressure and cutting rate. The fluid flow observed is very different between BSS and AV tests.

CONCLUSIONS

The DB has more efficient fluidics than SB vitrectomy probe in all tested conditions. Fluid acceleration depends on the cutting frequency, especially in the case of measurements in AV. The flow rate strongly depends on the pressure and it is little affected by the cutting frequency, in a range of clinical interest. The 27-G DB produces flow rates similar to the 23- and 25-G SB, with significantly smaller acceleration. The flow induced in the AV is different from that in BSS and oscillates at different frequencies.

TRANSLATIONAL RELEVANCE

DB cutters prove to be more efficient in terms of lower acceleration for a given flow rate. The latter is mainly controlled by aspiration pressure and less by cut rates. The influence of vitreous rheology deserves further investigations.

Retrospective Comparison of 27-Gauge and 25-Gauge Microincision Vitrectomy Surgery with Silicone Oil for the Treatment of Primary Rhegmatogenous Retinal Detachment

Aim

To retrospectively compare the safety and effectiveness of 27-gauge (27G) microincision vitrectomy surgery (MIVS) with 25-guage (25G) MIVS for the treatment of primary rhegmatogenous retinal detachment (RRD) with silicone oil tamponade.

Methods

Ninety-two patients with RRD who underwent MIVS from May 1, 2015, to June 30, 2017, were included in this study. Fifty-eight eyes underwent 25G MIVS and 34 eyes underwent 27G MIVS. We analyzed the characteristics of the patients, surgical time, main clinical outcomes, and rate of complications.

Results

The mean surgical time was 56.7 ± 35.9 min for the 25G MIVS and 55.7 ± 36.1 min for the 27G MIVS, and there was no significant difference (P=0.894) between the two groups. The primary anatomical success rate after a single operation was 94.8% for 25G MIVS and 91.2% for 27G MIVS (P=0.666). Baseline and final visit best-corrected visual acuity (BCVA) were 1.9 ± 1.1 and 1.0 ± 0.8 in the 25G group, and 1.7 ± 1.0 and 1.1 ± 0.8 in the 27G group. Last visit BCVA increased significantly in both groups (P < 0.001). However, there were no significant differences in terms of visual improvement ratio (>0.2 logMAR) between the two groups (P=0.173). No severe intraoperative complication was observed. Iatrogenic retinal breaks occurred in 2 eyes (3.4%) in the 25G group and 1 eye (2.9%) in the 27G group during the peripheral vitreous base shaving. The transient ocular hypertension (>25 mmHg) within postoperative week 1 was 25.9% in the 25G group and 11.8% in the 27G group (P=0.120).

Conclusions

This study found no significant anatomical or functional difference between 27G and 25G MIVS in the treatment of primary RRD. Therefore, 27G vitrectomy appears to be a safe and effective surgery for the treatment of primary RRD.

Twenty-seven-gauge vitrectomy for combined tractional and rhegmatogenous retinal detachment involving the macula associated with proliferative diabetic retinopathy

Background

To report our experience using 27-gauge pars plana vitrectomy (PPV) system for treating patients with combined tractional and rhegmatogenous retinal detachments (CTRRD) involving the macula associated with proliferative diabetic retinopathy (PDR).

Methods

Retrospective noncomparative interventional cases series of 12 patients with CTRRD associated with PDR who underwent 3-port, transconjunctival 27-gauge PPV by a single surgeon. Main outcome measures were change in Snellen best corrected visual acuity (BCVA) and occurrence of intra- and post-operative complications.

Results

Twelve eyes from 12 patients (9 men and 3 women) underwent 27-gauge PPV. Mean follow-up was 17 months (range 8–26 months). Preoperatively, BCVA of 20/400 or better was recorded in only 2 of 12 (16.7%) eyes. Postoperatively, BCVA improved to 20/400 or better in 11 of 12 (91.7%) eyes at 6 months (P = 0.001). At last follow-up, BCVA of 20/400 or better was recorded in 10 of 12 (83.3%), in comparison to 2 (16.7%) eyes at baseline (P = 0.004). The only intraoperative complication was an iatrogenic break in 1 eye (8.3%). Postoperative complications included vitreous hemorrhage in 4 eyes (33.3%) and transient ocular hypertension in 3 eyes (25.0%). At final follow-up anatomic success was confirmed in all eyes.

Conclusion

The current study findings suggest that 27-gauge PPV is a safe and promising surgical technology for treating patients with CTRRD involving the macula associated with PDR. Smaller gauge instruments and higher cutting rates may facilitate the dissection and shaving of fibrovascular membranes, while minimizing intra- and post-operative complications.

Electronic supplementary material

The online version of this article (doi:10.1186/s40942-017-0091-x) contains supplementary material, which is available to authorized users.

Vitreoretinal instruments: vitrectomy cutters, endoillumination and wide-angle viewing systems

There have been many advances in vitreoretinal surgery since Machemer introduced the concept of pars plana vitrectomy, in 1971. Of particular interest are the changes in the vitrectomy cutters, their fluidics interaction, the wide-angle viewing systems and the evolution of endoillumination through the past decade and notably in the last few years. The indications of 27-gauge surgery have expanded, including more complex cases. Cut rates of up to 16,000 cuts per minute are already available. New probe designs and pump technology have allowed duty cycle performances of near 100% and improved flow control. The smaller vitrectomy diameter can be positioned between narrow spaces, allowing membrane dissection and serving as a multifunctional instrument. Enhanced endoillumination safety can be achieved by changing the light source, adding light filters, increasing the working distance and understanding the potential interactions between light and vital dyes commonly used to stain the retina. Wide-angle viewing systems (contact, non-contact or a combination of both) provide a panoramic view of the retina. Non-contact systems are assistant-independent, while contact systems may be associated with better image resolution. This review will cover some current aspects on vitrectomy procedures, mainly assessing vitrectomy cutters, as well as the importance of endoillumination and the use of wide-angle viewing systems.

Porcine Vitreous Flow Behavior During High-Speed Vitrectomy up to 7500 Cuts per Minute

Purpose

To evaluate the impact of high-speed cut rates (up to 7500 cuts per minute [cpm]) on vitreous flow through various gauge probes.

Methods

An open-sky vitrectomy technique was performed on porcine eyes using the CONSTELLATION Vision System with three different gauges of dual-pneumatic probes (27⁺-, 25⁺-, and 23-gauge UltraVit probes; n = 5 for each gauge). Flow rate was calculated by LabVIEW software that converted real-time mass measurements from an electronic scale into flow rate.

Results

Average vitreous flow rate increased slightly with increased cut rate in all probes with 50/50 duty cycle; more dramatic flow rate increases were observed for all probes with biased closed duty cycle. Under both conditions, maximum flow rate was observed at 7500 cpm for all gauges. Under the biased open duty cycle, average flow rate was inversely associated with cut rate.

Conclusion

High-speed cut rate improved efficiency of vitreous aspiration.

Translational Relevance

Increased vitreous aspiration of dual-pneumatic, high-speed vitrectomy probes may improve the efficiency of current vitrectomy techniques, allowing surgeons to take advantage of the benefits of high cut rates without sacrificing flow rate.

INTRAOCULAR PRESSURE CHANGES DURING VITRECTOMY USING CONSTELLATION VISION SYSTEM'S INTRAOCULAR PRESSURE CONTROL FEATURE

PURPOSE

To evaluate intraocular pressure (IOP) changes during experimental vitrectomy and the efficacy of Constellation Vision System's IOP control (IOPc) feature in reestablishing baseline pressure.

METHODS

Using a pressure transducer in freshly enucleated porcine eyes, a broad range of parameters (baseline pressures, aspiration levels, and cut rates) were tested with 23- and 25-gauge probes and IOPc turned ON versus OFF.

RESULTS

IOPc turned ON was significantly more effective than IOPc turned OFF in controlling IOP drop and stabilizing pressure during vitrectomy using a wide range of baseline pressures (20-70 mmHg). The 23-gauge system consistently presented a reduced drop from baseline compared with the 25-gauge system. The overall average drop for the 23- and 25-gauge systems was 12.79 mmHg and 21.17 mmHg, respectively. Both gauge sizes reestablished baseline pressure approximately 1.6 seconds after the initial pressure drop generated at the beginning of aspiration. A peak of IOP (overshooting) was observed when the pressure was returning to baseline using both 23- and 25-gauge systems.

CONCLUSION

Using IOPc feature turned ON, 23- and 25-gauge probes were effective in reestablishing and sustaining baseline infusion pressures, although 23-gauge probes showed less IOP fluctuation than did 25-gauge probes.

Outcomes of 27 Gauge Microincision Vitrectomy Surgery for Posterior Segment Disease

PURPOSE

To report the initial experience, clinical outcomes, and safety profile of 27 gauge pars plana vitrectomy (PPV) in eyes with posterior segment disease.

DESIGN

Multicenter, retrospective, interventional case series.

METHODS

setting: Private practice and tertiary care settings.

STUDY POPULATION

Eyes undergoing 27 gauge PPV for a vitreoretinal surgery indication.

INTERVENTION

Three-port, transconjunctival 27 gauge PPV.

MAIN OUTCOME MEASURES

Change in visual acuity and occurrence of intraoperative and postoperative complications with minimum follow-up of 90 days.

RESULTS

Ninety-five eyes met the inclusion criteria. Surgical indications included epiretinal membrane (n = 26), diabetic tractional retinal detachment (n = 14), full-thickness macular hole (n = 11), rhegmatogenous retinal detachment with (n = 7) or without (n = 9) proliferative vitreoretinopathy (PVR), vitreous hemorrhage (n = 10), vitreous opacities (n = 8), endophthalmitis (n = 4), sub-silicone oil retinal detachment (n = 3), retained lens material (n = 1), submacular hemorrhage (n = 1), and aqueous misdirection (n = 1). Mean logMAR visual acuity improved from 1.08 ± 0.71 (20/240 Snellen equivalent) preoperatively to 0.53 ± 0.65 (20/67 Snellen equivalent) postoperatively (P < .001). Mean follow-up was 144 days (median 127 days, range 90-254 days). There were no intraoperative complications and no case required conversion to 20, 23, or 25 gauge instrumentation. A total of 3 sclerotomy sites (1.1%) were sutured at the conclusion of surgery. Postoperative complications included transient ocular hypertension in 8 eyes (8.4%), transient hypotony in 5 eyes (5.3%), and vitreous hemorrhage in 5 eyes (5.3%). No cases of postoperative endophthalmitis, sclerotomy-related retinal tears, or choroidal detachments were encountered in the follow-up period.

CONCLUSION

The 27 gauge PPV was well tolerated with low rates of intraoperative and postoperative complications across varied surgical indications.