High infusion pressure in conjunction with vitreous surgery alters the morphology and function of the retina of rabbits

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.

Relationship between retinal capillary vessel density of OCT angiography and intraocular pressure in pig

The purpose of this study was to evaluate density change in the retinal capillary plexus during intra ocular pressure (IOP) elevation in vitrectomized pigs’ eyes using optical coherence tomography angiography (OCTA). Eight eyes of eight micro pigs received vitrectomy and the IOP was controlled from 15 mmHg (baseline) to 105 mmHg in 15 mmHg increments using a vented-gas forced-infusion system, and then decreased back to normal IOP (recovery state). The spectral-domain OCTA device was set to scan an area of 8.8 × 4.4 mm (30° × 15°) above the optic nerve head for each IOP. The relative vessel density (rVAD) compared to baseline was determined for the total retinal blood flow (RBF) which included major retinal artery and venous vessels, radial peripapillary capillaries (RPCs), superficial (SVP), intermediate (IVP), and deep vascular plexus (DVP). The mean rVAD was 0.890 in RBF, 0.826 in RPCs, 0.817 in SVP, 0.819 in IVP, and 0.794 in DVP at 30 mmHg. While the rVAD of RBF and RPCs decreased to 0.504 and 0.541 at 45 mmHg, the SVP, IVP, and DVP decreased to 0.433, 0.359, and 0.345, respectively. When IOP was normalized, the rVAD was recovered in all layers and the VAD of RBF, IVP, and DVP were higher than baseline (P = 0.040, 0.019, and 0.019, respectively). Retinal capillary density deterioration in each layer was found from 30 mmHg using an OCTA system which showed excellent depth-resolved segmentation of retinal capillary layers even at higher IOPs. Reduction in VAD showed full recovery after IOP normalization.

Influence of Perfluorocarbon Liquids on Peripapillary Retinal Nerve Fiber-Layer Thickness Following Pars Plana Vitrectomy with Silicone Oil-Based Endotamponade

Background

Inner retina–layer modifications after pars plana vitrectomy (PPV) can be objectively assessed through spectral domain optical coherence tomography (SD-OCT).

Methods

This study explored prospectively changes in retinal nerve-fiber layer (RNFL) thickness with SD-OCT in eyes undergoing PPV with silicone oil–based tamponade with and without use of perfluorocarbon liquids (PFCLs) during the early postoperative phase (up to 3 months) at the Research Institute of Ophthalmology, Egypt.

Results

Thirty patients were recruited who underwent PPV and silicone oil–based tamponade for either retinal detachment or diabetic retinopathy between April 2019 and September 2019. Mean RNFL thickness showed no significant change during follow-up at the first week (102.90±30.68 mm), 1 month (107.30±32.27), or three months (105.90±36.68; p=0.46, 0.68). There were significant correlations noticed between RNFL thinning and axial length of eyes, intraocular pressure, and use of PFCLs during the follow-up period.

Conclusion

The RNFL tends to change postvitrectomy, but not significantly. Careful examination and consistent follow-up is required for postvitrectomy patients with larger axial length and intraoperative PFCL use.

Ex Vivo Comparison of Intraocular Pressure Fluctuation During Pars Plana Vitrectomy Performed Using 25- and 27-Gauge Systems

INTRODUCTION

The purpose of this study was to compare intraoperative intraocular pressure fluctuation using different aspiration systems and 25- and 27-gauge vitreous surgery probes.

METHODS

Ex vivo, pars plana, 25- and 27-gauge vitreous surgery was performed on four porcine eyes, and IOP fluctuations were evaluated. We performed three-port vitrectomy using the Constellation® Vision or the EVA® Phaco-Vitrectomy system. Each 20-s experiment was conducted five times for each set of conditions, each with the same substituted balanced salt solution. Real-time intraoperative intraocular pressure measurement was performed at the distal end of the infusion tube. Intraocular pressure was measured during core vitrectomy; core vitrectomy with fluid aspiration; peripheral vitreous shaving with scleral indentation; and fluid-gas exchange. The Mann-Whitney U test was used to evaluate statistical significance.

RESULTS

Mean ± standard deviation intraoperative intraocular pressure fluctuation during 25- and 27-gauge core vitrectomy were 15.9 ± 1.6 mmHg and 11.9 ± 1.4 mmHg, respectively (P < 0.05), using the Constellation system; 23.2 ± 1.4 mmHg and 14.1 ± 0.7 mm Hg, respectively (P < 0.001), using the EVA vacuum mode; and 15.0 ± 0.5 mmHg and 11.5 ± 1.4 mmHg, respectively (P < 0.05), using the EVA flow mode. The smallest intraoperative intraocular pressure fluctuations during core vitrectomy with fluid aspiration, peripheral vitreous shaving with scleral indentation, and fluid-gas exchange, were all achieved using the 27-gauge EVA flow mode; these values were 14.2 ± 0.4 mmHg, 35.7 ± 0.9 mmHg, and 6.4 ± 0.2 mmHg, respectively.

CONCLUSION

Regardless of the aspiration system, intraoperative intraocular pressure fluctuation was lower during 27-gauge than during 25-gauge vitrectomy. The 27-gauge EVA flow mode produced optimal intraoperative intraocular pressure stability.

Elevated intraocular pressure causes cellular and molecular retinal injuries, advocating a more moderate intraocular pressure setting during phacoemulsification surgery

PURPOSE

To evaluate the cellular and molecular retinal injuries induced by various intraocular pressure (IOP) settings in a mouse model of acute ocular hypertension (AOH), and to advise using a more moderate target IOP during phacoemulsification (phaco) surgery.

METHODS

A mouse model of AOH that mimics a transient IOP elevation during phacoemulsification cataract surgery was established. Six groups with various settings of target IOP were included. Retinal tissues were assessed with terminal deoxynucleotidyl transferase-mediated 2'-deoxyuridine 5'-triphosphate nick end-labeling (TUNEL) staining for neuron loss, immunofluorescence with Iba1 for microglia activation, and quantitative real-time polymerase chain reaction analysis with tight junction proteins (claudin-3 and claudin-5) or classic inflammation markers (IL-1β and eNOS) for impairment of the blood-retinal barrier (BRB) and inflammatory injury.

RESULTS

Compared with those in the 45-mmHg IOP group, significantly increased number of neurons loss and increased microglia activation were observed in 90-mmHg IOP group. In addition, the expression of claudin-3 and claudin-5 was significantly decreased, while the expression of IL1-β and eNOS was up-regulated, indicating impairment of the BRB and inflammatory injury in the retina. Furthermore, these findings of neuron loss, microglia activation, and inflammation in the 90-mmHg groups were exacerbated when an IOP-induced retinal injury was established 5 days earlier, while those in the 45-mmHg groups remained almost unchanged.

CONCLUSIONS

In conclusion, these results showed that a relatively commonly used high IOP setting (90 mmHg) could induce significantly more serious retinal injury. An IOP setting around 45 mmHg is relatively safe and might be recommended in phaco surgery, especially in patients with advanced glaucoma, previous acute angle closure crisis, or other diseases with fragile retina and optic nerve.

Effects of perfluorooctane on the retina as a short-term and small amounts remnant in rabbits

AIM

To investigate changes in the rabbit retina after short-term and small amounts tamponade of perfluorooctane (PFO).

METHODS

New Zealand rabbits were used, and 48 eyes were randomly and evenly assigned into four different groups. The PFO groups received a residue of 0.1 mL of PFO for ophthalmic surgery or 0.1 mL of F-Octane at the end of surgery; eyes from the pars plana vitrectomy (PPV) group were filled with balanced salt solution and those having not received surgical intervention served as controls. Eyes were collected at 1, 4 and 12wk and studied.

RESULTS

Under a microscope, nuclear counts of the inner nuclear layer (INL) and outer nuclear layer (ONL) did not differ among the four groups at all time points; however, slight disarrangement of the ONL and occasional vacuolization of the INL were found in the inferior retina only at 12wk in two PFO groups. Four of the groups had similar results of Caspase-3 and TNF-α staining at all time points. Alternatively, IL-8 was increased in PFOa and PPV control groups at 4wk and in all three PPV groups at 12wk; also, the apoptotic index (%) was similarly increased in all three PPV groups at 4 and 12wk.

CONCLUSION

Both PFOs are well tolerated in rabbit eyes for up to 12wk, which suggests that they can be used safely as intraoperative tools or for short-term and small amounts tamponade after surgery.

Effect of infusion pressure during cataract surgery on ganglion cells measured using isolated-check visual evoked potential

AIM

To detect the relationship between infusion pressure and postoperative ganglion cells function.

METHODS

This prospective observational cohort study included sixty-one eyes that underwent uncomplicated cataract surgery. Patients were divided into two groups according to infusion time (IT) recorded using surgery equipment [Group A: IT>IT_mean (27 eyes); Group B: IT<IT_mean (34 eyes)]. Best-corrected visual acuity, isolated-check visual evoked potential (icVEP), microperimetry, and optical coherence tomography examinations were performed preoperatively and 1wk and 1mo postoperatively. The changes in test results were measured with independent-sample t-tests and paired t-tests. Correlation between IT and these changes were analyzed with Pearson's correlation analysis and Spearman correlation analysis.

RESULTS

Neither group showed significant postoperative changes in macular ganglion cell-inner plexiform layer (mGC-IPL) thickness (1-week postoperative: Group A P=0.185, Group B P=0.381; 1-month postoperative: Group A P=0.775, Group B P=0.652). Postoperative mGC-IPL thickness of Group A was not significantly thicker than that of Group B at both post surgery time point (1-week postoperative P=0.913; 1-month postoperative P=0.954). In Group A, the mGC-IPL thickness change 1wk postoperatively was positively correlated with IT (R²=0.156, P=0.0198). A suspected progressive deficit in the magnocellular pathway was also found in Group A 1-month postoperatively [individual observed F (IOF)=0.63±0.70]. Significant increases were observed in postoperative retinal sensitivity measured by microperimetry (1-week postoperative: Group A P=0.015, Group B P<0.001; 1-month postoperative: Group A P=0.005, Group B P<0.001). In Group B, IT was negatively correlated with the increase in macular sensitivity (1-week postoperative: R²=0.372, P<0.001; 1-month postoperative: R²=0.209, P=0.007).

CONCLUSION

Both mGC-IPL thickness and retinal sensitivity increased postoperatively. A suspected progressive deficit in the magnocellular pathway was found in the group with a long IT, which induced more prominent changes.

Ocular perfusion pressure control during pars plana vitrectomy: testing a novel device

PURPOSE

To study the efficacy of a novel device intended to control infusion pressure based on mean ocular perfusion pressure (MOPP) during pars plana vitrectomy (PPV).

METHODS

An arm blood pressure cuff connected to a vitrectomy machine calculated mean arterial pressure (MAP), while a pressure sensor close to the infusion trocar measured intraocular pressure (IOP). MOPP was calculated in real time in 36 consecutive patients undergoing PPV, who were divided into two groups. The device lowered IOP every time that calculated MOPP fell below 30 mmHg in the Control ON group (18 patients), while no action was taken in the Control OFF group (18 patients).

RESULTS

Baseline IOP and blood pressure were similar between groups. The Control ON group had significantly lower average intraoperative IOP (30.5 ± 2.1 vs. 35.9 ± 6.9 mmHg; p = 0.002) and higher MOPP (56.4 ± 5.9 vs. 49.7 ± 6.1 mmHg) than the Control OFF group. The Control ON group also spent less time at MOPP < 10 mmHg and < 30 mmHg: 0 vs. 3.40 ± 2.38 min (p < 0.001) and 9.91 ± 7.15 vs. 16.13 ± 8.12 min (p = 0.02), respectively.

CONCLUSIONS

The MOPP control device effectively maintained lower IOP and higher MOPP throughout surgery. It also helped avoid dangerous IOP peaks and MOPP dips, allowing patients to spend less time at MOPP of < 10 and < 30 mmHg.

In vivo intraocular pressure monitoring during microincision vitrectomy with and without active control of infusion pressure

PURPOSE

To evaluate intraocular pressure (IOP) fluctuation during vitrectomy, we directly monitored IOP in vivo using 2 vitrectomy machines with or without constant infusion pressure monitoring and control.

METHODS

Among 61 eyes of 61 consecutive patients, 32 were assigned to the Accurus system (group 1) and 29 were assigned to the Constellation system (group 2) in this prospective case series. The IOP fluctuations were evaluated during routine vitrectomy procedures.

RESULTS

The initial IOP before vitrectomy was 20.3 ± 2.4 mm Hg in group 1 using a conventional vented gas forced infusion system and 20.0 ± 0.0 mm Hg in group 2 using active IOP control at 20 mm Hg (p = 0.532). However, the average IOP change during core vitrectomy was -8.6 ± 4.3 mm Hg in group 1 and -0.8 ± 1.1 in group 2 (p<00.001). Maximum IOP was significantly decreased in group 1 (-17.0 ± 2.6 mm Hg) compared with that in group 2 (-4.1 ± 2.2 mm Hg) (p<00.001). Partial ocular collapse was observed during vitrectomy only in group 1 (78.1%). Peak IOP significantly increased during scleral compression and gas and fluid injection but was not significantly different between the groups (all p≥0.147). The IOP fluctuation range was 50-70 mm Hg in both groups.

CONCLUSIONS

The IOP fluctuated significantly during routine vitrectomy using both systems. Hypotony and partial ocular collapse were more frequently observed during vitrectomy with the Accurus system than with the Constellation system. Both systems were vulnerable to IOP surge during indentation and intravitreal injection.

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.

Cyclopexy versus vitrectomy combined with intraocular tamponade for treatment of cyclodialysis

AIM

To compare the effects and complications of direct cyclopexy (DC) versus vitrectomy, endophotocoagulation, and gas/silicone oil endotamponade (VEE) treatment in patients with cyclodialysis and persistent hypotony.

METHODS

This is a prospective, comparative, nonrandomized clinical trial which includes 52 patients with cyclodialysis and persisting hypotony. Fifty-two patients suffering from cyclodialysis and persistent hypotony in one eye were divided into 2 groups (groups DC and VEE) and treated, respectively, with direct cyclopexy or vitrectomy, endophotocoagulation, and gas/silicone oil endotamponade. The patients were followed up for 12 months. Assessments included best corrected visual acuity (BCVA), intraocular pressure (IOP), anterior chamber depth (ACD), anterior chamber volume (ACV) and subjective rating of the pain caused by the treatments.

RESULTS

After a follow-up of 12 months, significant improvement was seen in postoperative mean BCVA, IOP, ACD and ACV in both treatment groups (which were not significantly different from each other). The success rates for the treatments were not significantly different (DC: 50.0% vs VEE: 62.5%, P=0.383). Postoperative morbidity of cataract and subjective pain rating were significantly higher in the VEE group vs the DC group (P= 0.003 and P<0.001 respectively).

CONCLUSION

DC and VEE were effective surgical procedures in treating patients with cyclodialysis and persistent hypotony. Patients had better tolerance to DC treatment and VEE was more likely lead to cataract complications. Taking into consideration the ease of the operation, success rate, and patient comfort, DC treatment seems preferable to VEE treatment in patients with simple cyclodialysis. While VEE has the advantage of treating patients with cyclodialysis combined with vitreous hemorrhage.

Changes in glutamate homeostasis cause retinal degeneration in Royal College of Surgeons rats

The aim of the present study was to investigate glutamate homeostasis in retinal degeneration-induced changes and the potential mechanisms of glutamate-mediated excitotoxicity in a rat model. The expression of vesicular glutamate transporter-1 (VGLUT-1) and protein kinase Cα (PKCα) in wild-type and Royal College of Surgeons (RCS) rat retinas, at postnatal Day 15 (P15), P30, P60 and P90, were detected using quantitative real-time polymerase chain reaction and immunohistochemistry. The levels of glutamine synthetase (GS) and L-glutamate/L-aspartate transporter (GLAST) were evaluated by western blotting. Compared with wild-type rats, outer nuclear layer thickness was significantly thinner and VGLUT-1 expression was upregulated in a time-dependent pattern in RCS rats. The ratio of VGLUT-1 to PKCα in RCS rats peaked at P60 (p<0.01) and subsequently decreased by P90 (p<0.01), while it remained constant in wild-type rats. The expression of GS increased gradually from P30 to P90 in RCS rats (p<0.01), while it remained constant in wild-type rats at various time-points. No significant difference in GLAST expression was found between RCS and wild-type rats at all stages of retinal degeneration. Our results confirm the occurrence of glutamate-mediated excitotoxicity to RCS rat retinas and provide an experimental foundation for safeguarding the remnant visual function in retinal degenerative disorders.

Changes of intraocular pressure during experimental vitrectomy

PURPOSE

To compare the infusion pressure shown by a vitrectomy device with the actual intraocular pressure (IOP) observed during pars plana vitrectomy. Furthermore, we evaluated the effects of variable parameters on the actual IOP during vitrectomy surgery.

MATERIALS AND METHODS

Porcine eyes were obtained within 24 h of slaughter. Actual IOP was measured by a digital manometer during vitrectomy using the vented gas forced infusion (VGFI) system, as well as the gravity system. We analyzed the actual IOP according to the groups divided by remnant volume of infusion fluid: (500 ml; control group, 250, 125, and 50 ml). Finally, actual IOP was determined after changing variable parameters such as cutting rate, vacuum pressure, and the VGFI setting.

RESULTS

Settings for a VGFI system and pressure supplied by a gravity system significantly correlated with actual IOP (r = 0.99, p = 0.0001; r = 0.99, and p = 0.0001). Actual IOP declined with decreasing volume of infusion fluid. If the volume of infusion fluid was <125 ml, actual IOP decreased significantly compared with the control group and the difference in actual IOP reflected a significant difference in the VGFI setting of 30 mmHg. Cutting rate as well as VGFI setting and vacuum pressure affected actual IOP.

CONCLUSIONS

Infusion pressure shown by the vitrectomy device was similar to actual IOP in porcine eyes. However, volume of infusion fluid and variable parameters could change the actual IOP during pars plana vitrectomy. Our results may help to optimize the ideal parameters such as infusion pressure, vacuum pressure, and cutting rate of vitrectomy systems used to treat vitreoretinal diseases.

Testing the Biocompatibility of a Glutathione-containing Intraocular Irrigation Solution by Using an Isolated Perfused Bovine Retina Organ Culture Model — an Alternative to Animal Testing

The effects of a glutathione-containing intraocular irrigation solution, BSS Plus®, on retinal function and on the survival of ganglion cells in whole-mount retinal explants were studied. Evidence is provided that the perfused ex vivo bovine retina can serve as an alternative to in vivo animal testing. Isolated bovine retinas were prepared and perfused with an oxygen-saturated standard irrigation solution, and an electroretinogram was recorded to assess retinal function. After stable b-waves were detected, the isolated retinas were perfused with BSS Plus for 45 minutes. To investigate the effects of BSS Plus on photoreceptor function, 1mM aspartate was added to the irrigation solution in order to obtain a-waves, and the ERG trace was monitored for 75 minutes. For histological analysis, isolated whole retinal mounts were stored for 24 hours at 4°C, in the dark. The percentages of cell death in the retinal ganglion cell layer and in the outer and inner nuclear layers were estimated by using an ethidium homodimer-1 stain and the TUNEL assay. General swelling of the retina was examined with high-resolution optical coherence tomography. During perfusion with BSS Plus, no significant changes in a-wave and b-wave amplitudes were recorded. Retinas stored for 24 hours in BSS Plus showed a statistically significant smaller percentage (52.6%, standard deviation [SD] = 16.1%) of cell death in the retinal ganglion cell layer compared to the control group (69.6%, SD = 3.9, p = 0.0031). BSS Plus did not seem to affect short-term retinal function, and had a beneficial effect on the survival of retinal ganglion cells. This method for analysing the isolated perfused retina represents a valuable alternative for testing substances for their retinal biocompatibility and toxicity.

Characterization of the fluidic properties of a syringe-based portable vitrectomy device

PURPOSE

To compare the fluidic properties of the Intrector syringe-based vitrectomy device with other commercially available systems to evaluate its safety in the treatment of vitreoretinal diseases.

METHODS

Mean operator comfortable sustainable syringe plunger pull force was determined using a spring-loaded digital scale. Vacuum levels for syringes of different volumes (3, 5, and 10 mL) and pulling forces were quantified with a pressure transducer. Flow rates of water and egg white were measured both with the cutter at 600 cuts per minute and in the off position with the port open. Infusion flow of water was evaluated using a 1-mL syringe.

RESULTS

The mean plunger pull force among operators (n = 8) was 0.80 kg (SD, 0.20 kg). Using the 3-mL syringe with 0.91 kg pull force, mean vacuum level was 135.9 mmHg (SD, 4.8 mmHg) and mean cutter-on flow rates of water and egg white were 1.9 mL/min (SD, 0.1 mL/min) and 0.5 mL/min (SD, 0.1 mL/min), respectively. Larger-bore syringes generated lower vacuum levels and liquid flow rates.

CONCLUSION

The fluidic parameters of the Intrector vitrectomy device measured in this study suggest that at comfortable sustainable syringe pull forces, vacuum levels and liquid aspiration rates are similar to some other commercially available systems and are likely safe.

Fluid dynamics in three 25-gauge vitrectomy systems: principles for use in vitreoretinal surgery

PURPOSE

To compare infusion and extrusion fluid volumes with three 25-gauge vitrectomy systems.

METHODS

The infusion and aspiration rates of 25-gauge systems from Alcon (Fort Worth, TX, USA), Bausch & Lomb (St Louis, MO, USA), and the Dutch Ophthalmic Research Centre (DORC, Zuidland, the Netherlands) were measured in vitro using balanced saline solution with different heights (40, 60, 80, 100, 120 cm) of infusion bottle, cutter velocities (800, 1100, 1500 cuts/ min) and aspiration powers (100, 200, 300, 400, 500 mmHg).

RESULTS

The infusion flow velocities differed among the systems (p < 0.001 for all comparisons [p-values 0.0009-0.0001]). The aspiration rates of the Alcon and Bausch & Lomb systems were lower than that of the DORC system (p < 0.02 for all comparisons [p-values 0.018-0.002]).

CONCLUSIONS

Infusion and extrusion fluid rates differ among 25-gauge vitrectomy systems. These results may help to optimize ideal aspiration and infusion parameters among 25-gauge vitrectomy systems used to treat vitreoretinal diseases.