Intraoperative Intraocular Pressure Research Articles

Phacoemulsification using an active fluidics system at physiologic vs high intraocular pressure: impact on anterior and posterior segment physiology.

Evaluate the impact of high vs low intraoperative intraocular pressure (IOP) during phacoemulsification on anterior and posterior physiology. Private practice in Des Moines, Iowa. Prospective, randomized, paired-eye clinical trial of patients anticipating bilateral cataract surgery. 27 participants randomized at the time of their first cataract surgery to either low IOP or high IOP group. The subsequent cataract surgery was performed under the alternate condition. During phacoemulsification and cortex removal, IOP was maintained either at low (≤28 mm Hg) or at high (≥55 to 60 mm Hg) levels. The primary outcome was fluid usage, with secondary outcomes of central corneal thickness, foveal avascular zone area, foveal and macular thickness, endothelial cell density (ECD), and postoperative inflammation. Surgery with low IOP settings used less fluid (40.0 mL vs 55.6 mL, P < .0001). Corneal thickness changes were smaller in low IOP eyes at 1 day and 1 week (3.0% vs 8.1%, P = .01; 3.1% vs 4.4%, P = .01) but were similar by 1 and 3 months. ECD dropped less in low IOP eyes at 1 and 3 months (-1.7% vs -12.3%, P = .001, 2.1% vs -8.9%, P = .0003.) IOP remained a significant predictor of ECD change when relationship was controlled for fluid use and phacoemulsification energy. Retinal parameters did not vary among all eyes or when compared by IOP setting. Visual acuity was similar at all timepoints. Low IOP settings resulted in less inflammation and less corneal trauma, as evidenced by a smaller drop in ECD and less postoperative corneal edema, when compared with high IOP settings. Retinal parameters did not change significantly. The different outcomes did not result in a difference in visual acuity.

Оценка клинической эффективности нового способа адаптивного управления инфузией при факоэмульсификации

Reduction of the adverse effects of intraoperative intraocular pressure fluctuation referred to as post-occlusion surge on the intraocular structures is an important task for ensuring phacoemulsification safety. In this regard, the method to control infusion during phacoemulsification based on controlling the infusion and aspiration flow rates in combination with monitoring of vacuum parameters was developed. The study was aimed to provide comparative assessment of clinical and functional characteristics of the eye in patients after phacoemulsification using the new and already existing adaptive infusion control methods. A total of 38 patients aged 66.4 ± 7.8 years (15 males and 23 females) in the index group (Optimed Profi system with the use of new method) and 35 patients aged 68.7 ± 7.5 years (16 males and 19 females) in the control group (Centurion Vision System with Active Fluidics) underwent surgery due to cataract. The patients underwent comprehensive eye examination before surgery and on days 1, 7, 30, months 3, 6 after surgery. The smaller loss of corneal endothelial cells on months 3 and 6 after surgery was observed in patients of the index group with grade III and IV cataract (p &lt; 0.05). Comparison of macular microcirculation parameters revealed the reduced FAZ area by month 6 of postoperative follow-up in the index group, along with the increased total vascular density of the deep vasculature (p &lt; 0.001). A significant decrease in the total density of the superficial and deep vascular plexuses by month 6 of postoperative follow-up was observed in the control group (p &lt; 0.05). The use of new adaptive infusion control method contributes to effective phacoemulsification of cataracts of varying density with the lower percentage of the corneal endothelial cells lost in the late postoperative period.

Increase in intraoperative intraocular pressure in the prone position

Increase in intraoperative intraocular pressure in the prone position

Direct Exchange of PerfluoroCarbon Liquid for Silicone Oil: A Surgical Technique to Control Pressure and Avoid Retinal Slippage.

Perfluorocarbon heavy liquid (PFCL) is used in vitreoretinal surgery to flatten the unsupported detached retina before insertion of silicone oil in cases of giant retinal tear or relaxing retinectomy. Direct exchange of PFCL for silicone oil is recommended to reduce retinal slippage when compared with fluid-air exchange, but it is commonly regarded as a difficult procedure. We describe our technique for direct PFCL-silicone oil exchange using a 20-gauge drainage cannula, reliably avoiding the complications of retinal slippage and high intraoperative intraocular pressure. We present a consecutive case series of patients undergoing PFCL-oil exchange and explain, using Poiseuille's equation for laminar fluid flow through a cannula, the rationale for using a 20-gauge drainage cannula rather than smaller gauges to avoid high intraocular pressure. Twenty-six patients underwent PFCL-oil exchange from February 1, 2019, to September 30, 2019. There was no intraoperative retinal slippage or pressure-related complications. Postoperatively 20 patients underwent oil removal. Six suffered retinal redetachment, and 14 remained attached. The vision postoil removal ranged from 6/6 to hand movements. We are confident that the PFCL-oil exchange technique described here is reliable and safe. The use of a 20-gauge drainage cannula is recommended regardless of vitrectomy gauge.

Effect of different surgical positions on intraocular pressure: a cross-sectional study

BackgroundIntraoperative intraocular pressure (IOP) elevation is a risk factor for postoperative blindness. Surgical position is associated with intraoperative IOP elevation. In China, there are few studies on the effect of various surgical positions on intraoperative IOP. This study was conducted to explore IOP change and its related factors in four common surgical positions in China.MethodsThis was a cross-sectional observational study. A total of 325 surgical patients who had non-ocular surgery from January 2019 to December 2019 in the hospital, were enrolled in this study. During their surgeries for general anesthesia, these participants were placed in lithotomy position/lateral position/prone position/supine position according to their surgery requirement. IOP was measured by icareTA03 handheld portable tonometer at 9 different time points from admission to exiting the operation room. And general information, postural position, and surgery information were collected through a uniform questionnaire. Multivariate analysis was performed to explore the related factors of IOP change.ResultsIOP of both eyes on lithotomy position, lateral position, and supine position showed statistical differences by ANOVA test at each time point (p < 0.05). IOP of both eyes in the prone position before exit from the operating room was significantly higher than IOP 10-min after anesthesia (p < 0.01). IOP under different postural angles showed statistical differences (F value = 4.85, P < 0.05), and the larger the head-down angle, the higher the IOP. IOP on the compressed side in the lateral position was higher than that on the non-compressed side (p < 0.01). In the multivariate linear regression analysis adjusted by other factors, postural position and baseline IOP were associated with IOP difference between before and after surgery (p < 0.01).ConclusionIOP in the four surgical positions showed different change patterns with the surgical process and position change. Nurses should assist the surgeon to reduce the head-down angle without interfering with the surgical operation and strengthen the inspection of IOP on patients with long-time surgery, to avoid intraoperative rapid IOP changes.

Contralateral Forced Eyelid Closure Increases Intraocular Pressure.

The purpose of the study was to describe the influence of contralateral forced eyelid closure on intraocular pressure (IOP). Twenty-one healthy volunteers with no ophthalmic history had their IOP measured in the supine position to simulate the intraoperative environment. Intraocular pressure was measured with a handheld tonometer over three scenarios: (1) both eyes in a relaxed state, (2) eyelid speculum in the right eye with both eyes open and relaxed, (3) eyelid speculum in the right eye with the fellow eye squeezing tightly. Intraocular pressure significantly increased with forced contralateral eyelid squeezing compared with the relaxed state by a mean of 7.71±5.08 mm Hg (95% Confidence Interval of 5.40-7.37), P<0.001. Contralateral eyelid squeezing can significantly increase intraoperative IOP measurements.

Факоэмульсификация катаракты на пониженных интраоперационных показателях

Purpose. To evaluate the clinical and functional results after cataract phacoemulsification with implantation of an intraocular lens at reduced intraoperative intraocular pressure, adapted vacuum and aspiration. Material and methods. 12 patients (24 eyes) with immature cataracts without concomitant eye pathology were included in the study. The age of patients was from 62 to 68 years. Patients were divided into 2 groups depending on intraoperative pressure parameters. The main group included 12 eyes with immature cataracts, which underwent phacoemulsification of the cataract with a reduced intraoperative intraocular pressure. 12 paired eyes, which underwent phacoemulsification of the cataract with IOL implantation with standard settings were included in the second (retrospective) group. Postoperative examination included checking visual acuity, tonometry, endothelial microscopy. The observation period was 1 day, 1 and 6 months. Results. Phacoemulsification of the cataract in both groups was performed without complications; operations were completed with intracapsular IOL implantation. It was noted that CDE of the main group was 2.79±0.64, and it was 2.9±0.82 in the control group during analyzing intraoperative indicators. The main differences were noted in indicators of the volume of fluid aspiration: 65.4±1.21 cm3 of the main group and 74.9±2.45 cm3 of the control group. The indicator of the volume of fluid aspiration of the control group was 14% more than that of the main group. After 6 months, the number of endothelial cells of the main group ranged from 1625 to 1935 cells/mm2, in the control group the number of endothelial cells ranged from 938 to 1745 cells/mm2. Conclusions. Performing phacoemulsification of cataract at close to normotonus values of intraoperative pressure parameters, as well as adapted indicators of irrigation-aspiration and vacuum, allows to reduce the negative effect on the corneal endothelium, reducing the percentage of complications and the postoperative period of rehabilitation of patients. Key words: cataract phacoemulsification, intraoperative intraocular pressure, reduced indicators.

Comparison of intraocular pressure during laparoscopic totally extraperitoneal (TEP) versus transabdominal preperitoneal (TAPP) inguinal hernia repair.

Laparoscopic totally extraperitoneal (TEP) repair and transabdominal preperitoneal (TAPP) repair are standard laparoscopic procedures for inguinal hernia repair. Some evidence has shown that pneumoperitoneum can cause an increase in intraocular pressure (IOP) during surgery. This study aimed to compare intraoperative IOP following extraperitoneal CO2 insufflation with the TEP approach and intraperitoneal CO2 insufflation with the TAPP approach. This study is a prospective cohort study. Patients who had inguinal hernias suitable for laparoscopic inguinal hernia repair were assigned to undergo the TEP or TAPP approach. We measured preoperative, intraoperative, and postoperative IOP. The IOP of the TEP and TAPP groups was evaluated using a t test. The relations between peak inspiratory pressure (PIP), mean arterial pressure (MAP), and end-tidal CO2 (EtCO2) were estimated using ANOVA. Univariate and multivariate analyses were performed to determine the factors associated with IOP. There were 50 patients in this study (TEP group n = 25, TAPP group n = 25). The change in intraoperative IOP from the preoperative measurement to the measurement after CO2 insufflation was not statistically significant in either the TEP or TAPP group (p value = 0.357). There was no significant difference in intraoperative IOP change between the TEP and TAPP groups. Intraoperative MAP and PIP were related to IOP, but intraoperative EtCO2 was not. There was no significant intraoperative IOP change during laparoscopic inguinal hernia repair. Both the TEP and TAPP techniques can be performed safely without increasing intraoperative IOP.

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 4 porcine eyes, and IOP fluctuations were evaluated. We performed 3-port vitrectomy using the Constellation® Vision or the EVA® Phaco-Vitrectomy system. Each 20-s experiment was conducted 5 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 was 15.9 ± 1.6 and 11.9 ± 1.4 mm Hg, respectively (p < 0.05), using the Constellation system; 23.2 ± 1.4 and 14.1 ± 0.7 mm Hg, respectively (p < 0.001), using the EVA vacuum mode; and 15.0 ± 0.5 and 11.5 ± 1.4 mm Hg, 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, 35.7 ± 0.9, and 6.4 ± 0.2 mm Hg, 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.

Intraoperative intraocular pressure changes during robot-assisted radical prostatectomy: associations with perioperative and clinicopathological factors

BackgroundSteep Trendelenburg position (ST) during robot-assisted radical prostatectomy (RARP) poses a risk of increase in intraocular pressure (IOP) in men receiving robot-assisted radical prostatectomy (RARP). The aim of the study was to identify clinicopathological factors associated with increased IOP during RARP.MethodsWe prospectively studied 59 consecutive prostate cancer patients without glaucoma. IOP was measured at 6 predefined time points before, during and after the operation (T1 to T6).ResultsCompared with T1, IOP decreased after beginning of anesthesia(T2) (by − 6.5 mmHg, p < 0.05), and increased 1 h after induction of pneumoperitoneum in the steep Trendelenburg position (ST) (T3) (+ 7.3 mmHg, p < 0.05). IOP continued to increase until the end of ST (T4) (+ 10.2 mmHg, p < 0.05), and declined when the patient was returned to supine position under general anesthesia (T5) (T1: 20.0 and T5: 20.1 mmHg, p above 0.05). The console time affected the elevation of IOP in ST; IOP elevation during ST was more prominent in men with a console time of ≥4 h (n = 39) than in those with a console time of < 4 h (n = 19) (19.8 ± 6.3 and 15.4 ± 5.8 mmHg, respectively, p < 0.05). Of the 59 patients, 29 had a high baseline IOP (20.0 mmHg or higher), and their IOP elevated during ST was also reduced at T5 (T1: 22.6 and T5: 21.7 mmHg, p above 0.05). There were no postoperative ocular complications.ConclusionsConsole time of < 4 h is important to prevent extreme elevation of IOP during RARP. Without long console time, RARP may be safely performed in those with relatively high baseline IOP.

The effect of preset intraoperative intraocular pressure during phacoemulsification on the blood flow velocity in the central retinal artery

Aim. To evaluate the effect of preset elevated intraocular pressure (IOP) level during phacoemulsification on central retina artery and central retinal vein hemodynamics and to determine possible compensatory mechanisms of the ocular blood flow autoregulation in response to intraoperational IOP jump.&#x0D; Methods. This prospective study included 23 cataract patients without concomitant ocular vascular conditions (15 women and 8 men) aged from 62 to 83 years. The mean age was 72.5 5.7 years. In all patients, an intraoperational color duplex scanning in the regimens of color Doppler imaging and pulsed wave velocity imaging using ultrasound scanner Logiq S8 (GE). The blood flow was estimated in retrobulbar vessels: central retinal artery, central retinal vein with maximal systolic velocity, end-diastolic velocity of the blood flow, and resistance index (RI). The investigation was performed under IOP control, which was measured using Icare Pro tonometer, and under blood pressure control using patient monitoring system Draeger Vista 120. In the operating room, ocular blood flow was examined three times: immediately before surgery, straight after the surgical incision sealing at preset intraoperational IOP level, and after IOP normalization and repeated sealing of the corneal tunnel.&#x0D; Results. Under preset intraoperational IOP maintenance on 58.01 8.10 mm Hg level, there was a clinically significant (p 0.05) decrease of blood flow velocity in the central retinal artery. In 30.4% of cases, the blood flow velocity in the central retinal artery during diastolic phase was not registered. The flow velocity in central retinal vein did not change significantly, and did not depend on IOP level (p 0.05).&#x0D; Conclusions. At the 5560 mm Hg IOP level, in humans, compensatory blood flow autoregulation mechanisms in response to intraoperational IOP jumps are absent, up to complete blood flow stop in the central retinal artery at the diastolic phase, and this could be a risk factor for retinal ischemia.

Reply.

In our article, the evidence of anterior vitreous detachment (AVD) during phacoemulsification was verified with intraoperative optical coherence tomography. We postulate that the condition being linked to cataract surgery complications. The major intraoperative issue resulting from AVD is bulging of the posterior capsule (PC) being pushed from behind toward the anterior chamber by the irrigating fluid currents. That results in PC rupture due to its contact with a vibrating ultrasound needle or capsule aspiration into the irrigation/aspiration tips. Both are usually happening at the final steps of lens removal. AVD is having various definitions in different publications. The plurality of terms describing more or less the same entities reflects the absence of clear understanding of the pathophysiological mechanisms of these conditions.1,2 We basically agree with the fact that there is an unmet need for the precise terminology that has to be clear and precise. Aqua is the Latin word meaning water, whereas aqueous is an adjective, generally used as a term that denotes a solution in which the main solvent is water. It is important not to confuse this with the term aqueous humor, which is secreted by intraocular tissues.3Aqueous misdirection does not clearly characterizes the deviated flow of a balanced salt solution but rather the deviated flow of the aqueous humor. Fluid is a phase of matter and is defined as a substance that flows. A fluid can be in different forms of liquid or gas.A This term is less specific in comparison with the term aqueous. But indeed, it is routinely used in ophthalmology to describe the accumulation of pathologic liquids in the eye, eg, subretinal fluid and corneal interface fluid after refractive surgery. The term fluid to our knowledge is more universal in comparison with aqueous, and its use in our situation might be more appropriate. However, it is still very broad and not specific enough; therefore, we do believe that infusion misdirection syndrome or irrigating fluid misdirection syndrome might be more clear and practical to use. The first term is shorter and well describes the major aspect of the pathophysiology based on the abnormal flow of the irrigating fluid or infusion. That is why it is our personal preference. We also propose the new classification of infusion misdirection syndrome that explains the acute intraoperative process. The initial grade is usually subclinical and may be hardly noticeable by the presence of the lens particles in the Berger's space (grade 1). The mild grade (2) can be characterized by shallowing of the anterior chamber with PC bulging forward up to the level of the anterior capsulorhexis, but without intraocular pressure elevation. Finally, the severe grade (3) is the condition originally classified as an acute intraoperative rock-hard eye syndrome, which is the term that underlines the advanced stage of infusion misdirection syndrome with the presence of acute intraoperative intraocular pressure rise. We do believe that malignant glaucoma is a different entity. It is usually associated with the fluid accumulation in between the retina and posterior vitreous in the postoperative period, resulting in the displacement of the whole vitreous forward blocking the anterior pathways of aqueous humor outflow. We therefore think that chronic fluid misdirection syndrome does not really emphasize the progressive nature of that disease leading to visual and structural deterioration.4 That is why we think that the definition of malignant glaucoma is to be used as it is.

Preoperative intraocular pressure as a strong predictive factor for intraocular pressure rise during vacuum application in femtosecond laser-assisted cataract surgery.

To evaluate the effect of preoperative intraocular pressure (IOP) and the vacuum level on IOP during femtosecond laser-assisted cataract surgery. Intraocular pressure was measured in 40 enucleated porcine eyes by intracameral manometry prior, during and after vacuum application using the VICTUS femtosecond laser platform (Bausch&Lomb, Technolas Perfect Vision GmbH, Germany). Twenty combinations of different preoperative IOP levels (12, 16, 20 and 24mmHg) and different vacuum levels (350-550mbar) were investigated. Multivariate regression analysis indicated that both the vacuum level (beta=0.138; p<0.001) but much stronger the preoperative IOP (beta=0.861; p<0.001) were predictive factors for IOP rise during vacuum application. Mean IOP was 28.23±3.86, 34.23±3.92, 40.35±4.41 and 46.82±4.11mmHg in groups with baseline IOP of 12, 16, 20 and 24mmHg, respectively. In the 350, 450 and 550mbar group, and mean IOP was 35.85±7.85, 37.33±7.90 and 39.00±8.04mmHg, respectively. Lowering the preoperative IOP by 2mmHg and reducing the vacuum from maximum to minimum resulted in a similar reduction in IOP during vacuum application (-3.10±0.79mmHg versus -3.15±0.88mmHg; p=0.015). Furthermore, decreasing the baseline IOP from 20 to 12mmHg resulted in a 30.0% reduction in intraoperative IOP. Preoperative IOP was a stronger predictive factor for intraoperative IOP rise than the applied vacuum level. Measurements and critical interpretation of preoperative IOP in a preliminary examination could help estimating the individual risk of significant IOP rise during femtosecond laser-assisted cataract surgery and could help taking early countermeasures in selected cases. Due to the porcine ex vivo model, further studies are needed to verify these findings.

Intraoperative intraocular pressure fluctuation during standard phacoemulsification in real human patients.

To evaluate the results of the fluctuations of intraocular pressure (IOP) and calculated mean ocular perfusion pressure (MOPP) during the usual steps of standard phacoemulsification. Nine human eyes were evaluated. The IOP was measured indirectly by electronic applanation tonometer. The MOPP was calculated using the systolic blood pressure (SBP), the diastolic blood pressure (DBP) and the IOP: MOPP = 2/3x[DBP + 1/3x(SBP - DBP)] - IOP. The operations were performed with the INFINITI® Vision System: main incision 2.2 mm, coaxial handpiece, 2 paracenteses 1.1 mm, bimanual irrigation/aspiration, bottle height 100 cm. As ocular viscoelastic device (OVD) Hypromel 2.5% (UNIMED) was used. The initial and final IOPs were 17-30 Torr (median 18) and 6-16 Torr (median 8), respectively. The IOP values oscillated between 4 and 63 Torr during the procedure. The highest values of the IOP were achieved at the beginning of phacoemulsification (from 42 to 63 Torr). The maximum pressure higher than 50 mmHg and 60 mmHg was found in 89% and 30% of cases, respectively. The mean ocular perfusion pressure (MOPP) at the beginning of the procedure was 46.4-67.0 (median 53.3) and 0.4-42.0 (median 19.3) during the maximum intraocular pressure. Measured IOP as well as MOPP varied in all normal steps of real phacoemulsification. High values of intraoperative IOL induced by irrigation may compromise the intraocular perfusion. These fluctuations may induce impairment of the optic nerve perfusion, as well as retina, or choroid.

Retinal nerve fiber layer thickness after laser-assisted subepithelial keratomileusis and femtosecond LASIK: a prospective observational cohort study.

PurposeBased on the assumption that high levels of intraocular pressure (IOP) during femtosecond laser-assisted in situ keratomileusis (FS-LASIK) may compromise the retinal nerve fiber layer (RNFL), newer femtosecond platforms that operate without causing significant IOP elevation have been developed in recent years. However, this assumption has not been adequately tested. The aim of the current study was to evaluate possible changes in RFNL thickness in nonglaucomatous myopic patients undergoing FS-LASIK using the 60 KHz IntraLase® device that significantly elevates the IOP for an appreciable period of time vs an advanced surface ablation technique (laser-assisted subepithelial keratomileusis, LASEK) that does not induce any IOP elevation.MethodsThis was a prospective, observational, controlled cohort study. One randomly selected eye of 114 consecutive eligible patients was analyzed. Inclusion criteria were myopia up to -6.00 diopters and astigmatism up to -2.00 diopters. As clinically indicated, 50 patients underwent LASEK and 64 underwent FS-LASIK. The RNFL thickness was determined with a spectral-domain optical coherence tomography device preoperatively and 3 months postoperatively by the same masked observer.ResultsThere was no significant difference in preoperative refractive error, age, or sex between the groups. Preoperatively, central corneal thickness was significantly lower in the LASEK group (529.1±36.1 vs 562.4±31.6 µm, P=0.001). For the LASEK group, there was no significant difference between preoperative and postoperative RNFL thickness in the studied sectors (superior-temporal, temporal, inferior-temporal, average). For the FS-LASIK group, compared to preoperative RNFL measures, statistically significant thicker postoperative values were found for the average RNFL (mean difference: 0.67 µm, 0.7% increase, P=0.008) and the inferior-temporal sector (mean difference: 0.92 µm, 0.6% increase, P=0.02).ConclusionLASIK with a femtosecond platform that induces high intraoperative IOP did not cause RNFL thinning. The observed differences between preoperative and postoperative values are below the axial resolution limit of optical coherence tomography devices.

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

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). 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 30mmHg in the Control ON group (18 patients), while no action was taken in the Control OFF group (18 patients). 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±6.9mmHg; p=0.002) and higher MOPP (56.4±5.9 vs. 49.7±6.1mmHg) than the Control OFF group. The Control ON group also spent less time at MOPP <10mmHg and <30mmHg: 0 vs. 3.40±2.38min (p<0.001) and 9.91±7.15 vs. 16.13±8.12min (p=0.02), respectively. 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 <30mmHg.

Considerations for refractive surgery in the glaucoma patient.

Given the popularity of keratorefractive surgery, and an aging populous of patients who have undergone these procedures, there is an increasing need for updated management protocols. This is particularly relevant for patients with chronic progressive diseases such as glaucoma, due to the variety of related diagnostic and management challenges inherent to these diseases. Here, we will review the current literature to provide an update on the management of patients with glaucoma who are undergoing, or have had laser ablative refractive surgery. Preoperative testing and eligibility considerations, intraoperative factors, and postoperative observation and follow-up will be discussed. Intraoperative intraocular pressure (IOP) rise during flap creation is associated with low risk of acute complications, and furthermore do not appear to have significant long term effects. Modern technologies have improved our ability to determine accurate IOP after refractive surgery despite postoperative changes in corneal architecture. Furthermore, advances in structural imaging allow for earlier detection of even subtle glaucomatous nerve damage. Although glaucoma remains a relative contraindication to refractive surgery, it is a safe procedure for many patients with appropriate perioperative management and follow-up. Advancements in diagnostic modalities have allowed for earlier detection of glaucomatous disease, and subsequent earlier intervention when appropriate. Standardized diagnostic algorithms and rigorous perioperative assessment are critical to safe management of glaucoma patients undergoing refractive corneal surgery.

Role of Initial Intraocular Pressure in Graft Adhesion After Descemet Membrane Endothelial Keratoplasty.

To analyze the role of initial intraoperative intraocular pressure (IOP) in graft adhesion in Descemet membrane endothelial keratoplasty (DMEK) during early follow-up. This retrospective, observational, single-center case series included 118 eyes from 118 consecutive patients treated between May and July 2015 for DMEK or combined DMEK and phacoemulsification (triple-DMEK). Exclusion criteria were previous eye surgery other than cataract surgery, loss of follow-up, any application of IOP-lowering medication before and after surgery, and low intraindividual repeatability of IOP measurements. The main outcome measure was graft adhesion that was correlated to the magnitude of IOP measured by Schiötz tonometry intraoperatively. Fifty-four eyes of 118 (45.8%) patients undergoing DMEK met the above-mentioned inclusion and exclusion criteria. In 43 (79.6%) eyes, complete graft adhesion was achieved at 1-week follow-up examination. Differences of the initial IOP in the presence of the air bubble were not statistically significant between eyes with complete and incomplete graft adhesion. Incomplete graft adhesion during early follow-up could not be associated with the magnitude of the initial IOP in DMEK. We found no evidence that higher IOP values enhance graft adhesion resulting in lower rebubbling rates after DMEK.

Influence of improved head-down tilt on the ocular complications of gynecological laparoscopic operation patients

Objective To study the influence of applying improved head-down tilt of thyroid slope cushion on the ocular complications of postoperative patients in gynecological laparoscopic operation. Methods A total of 120 patients who received total laparoscopic hysterectomy in our hospital from February to August in 2016 were selected, divided into control group (60 patients, traditional head-down tilt) and experimental group (60 patients, improved head-down tilt) randomly.The changes of preoperative, intraoperative and postoperative intraocular pressure, preoperative and postoperative ophthalmodynia in 2 hours, postoperative conjunctival congestion in 48 hours of patients in two groups were compared. Results The change level of intraocular pressure and ophthalmodynia of experimental group was superior to that of the control group, and the difference had statistical significance(P<0.05). The conjunctival congestion degree of experimental group was inferior to that of the control group, and the difference had statistical significance(P<0.05). Conclusions In gynecological laparoscopic operation, improved head-down tilt can improve intraocular pressure change and ophthalmodynia, reducing the complications of conjunctival congestion for patients, which has clinical application value. Key words: Improved head low position; Hysterectomy; Lapatroscopic surgery; Eye complication

Comparison of anterior chamber paracentesis before and after intravitreal gas injection

Objective To compare the clinical efficacy and complications of anterior chamber paracentesis before and after intravitreal gas injection. Methods Forty eyes of 32 cases with macular hemorrhage underwent intravitreal gas injection were enrolled.The patients were randomly divided into 2 groups.Patients in group A recieved the anterior chamber puncture before the intravitreal gas injection and patients in group B recieved the anterior chamber puncture after the intravitreal gas injection. The postoperative visual acuity, intraocular pressure(IOP), intraoperative and postoperative complications were observed. Results The postoperative visual acuity was improved to different degree in 92.5% patients, but the degree of improvement depended on the nature and timing of macular hemorrhage. The IOP in the group B during surgery was different compared to the IOP in the group A or group B after operation and the difference was statistically significant (P 0.05). The incidence of amaurosis, gas overflow, complicated cataract in group B were higher than that in group A, and the difference was statistically significant (P<0.05). The surgery was performed successfully in all cases and the postoperative IOP was controlled well without any other complications. Conclusion Anterior chamber puncture before intravitreal gas injection can soften the eyeball, avoid intraoperative IOP fluctuation which may cause serious complications, and is an effective means to improve the success rate of operation. Key words: Paracentesis, anterior chamber; Gas injection, intravitreal; Intraocular pressure, high; Hemorrhage, macular.