Retrobulbar anesthesia with and without hyaluronidase in extracapsular cataract surgery. A prospective, randomized, double-blind study

Orbital Dynamics and Efficacy of Retrobulbar Anesthesia With and Without Hyaluronidase in Vitreoretinal Surgery

Purpose: To compare retrobulbar anesthesia injection (RAI) with hyaluronidase and without hyaluronidase in vitreoretinal surgery using clinical efficacy measures and orbital manometry (OM). Methods: This prospective randomized double-masked study enrolled patients who had surgery using an 8 mL RAI with or without hyaluronidase. Outcome measures were clinical block effectiveness (akinesia, pain scores, need for supplemental anesthetic or sedative medications) and orbital dynamics assessed by OM before and up to 5 minutes after RAI. Results: Twenty-two patients received RAI with hyaluronidase (Group H+), and 25 received RAI without hyaluronidase (Group H-). Baseline characteristics were well matched. No differences in clinical efficacy were found. OM showed no difference in preinjection orbital tension (4 ± 2 mm Hg in both groups) or calculated orbital compliance (0.6 ± 0.3 mL/mm Hg, Group H+; 0.5 ± 0.2 mL/mm Hg, Group H-) (P = .13). After RAI, the peak orbital tension was 23 ± 15 mm Hg in Group H+ and 24 ± 9 mm Hg in Group H- (P = .67); it declined more rapidly in Group H+. Orbital tension at 5 minutes was 6 ± 3 mm Hg in Group H+ and 11 ± 5 mm Hg in Group H- (P = .0008). Conclusions: OM showed faster resolution of post-RAI orbital tension elevation with hyaluronidase; however, there were no clinically evident differences between groups. Thus, 8 mL RAI with or without hyaluronidase is safe and can achieve excellent clinical results. Our data do not support the routine use of hyaluronidase with RAI.

Ophthalmic regional blocks: management, challenges, and solutions

In the past decade ophthalmic anesthesia has witnessed a major transformation. The sun has set on the landscape of ophthalmic procedures performed under general anesthesia at in-hospital settings. In its place a new dawn has ushered in the panorama of eye surgeries conducted under regional and topical anesthesia at specialty eye care centers. The impact of the burgeoning geriatric population is that an increasing number of elderly patients will present for eye surgery. In order to accommodate increased patient volumes and simultaneously satisfy administrative initiatives directed at economic frugality, administrators will seek assistance from anesthesia providers in adopting measures that enhance operating room efficiency. The performance of eye blocks in a holding suite meets many of these objectives. Unfortunately, most practicing anesthesiologists resist performing ophthalmic regional blocks because they lack formal training. In future, anesthesiologists will need to block eyes and manage common medical conditions because economic pressures will eliminate routine preoperative testing. This review addresses a variety of topical issues in ophthalmic anesthesia with special emphasis on cannula and needle-based blocks and the new-generation antithrombotic agents. In a constantly evolving arena, the sub-Tenon's block has gained popularity while the deep angulated intraconal (retrobulbar) block has been largely superseded by the shallower extraconal (peribulbar) approach. Improvements in surgical technique have also impacted anesthetic practice. For example, phacoemulsification techniques facilitate the conduct of cataract surgery under topical anesthesia, and suture-free vitrectomy ports may cause venous air embolism during air/fluid exchange. Hyaluronidase is a useful adjuvant because it promotes local anesthetic diffusion and hastens block onset time but it is allergenic. Ultrasound-guided eye blocks afford real-time visualization of needle position and local anesthetic spread. An advantage of sonic guidance is that it may eliminate the hazard of globe perforation by identifying abnormal anatomy, such as staphyloma.

Hyaluronidase in sub-Tenon's anesthesia for phacoemulsification, a double-blind randomized clinical trial

AIM

To investigate the effect of hyaluronidase use on the quality of sub-Tenon's anaesthesia for phacoemulsification.

METHODS

This was a randomized, double-blind clinical trial which was conducted at Nikookari Eye Hospital for 5 months. Forty-two eyes of candidates for phacoemulsification under sub-Tenon's anaesthesia were randomly allocated to two equal groups and received either 2 mL of lidocaine 2% solution with (LH), or without (L) addition of hyaluronidase (150IU/mL). Akinesia was assessed 15 minutes after sub-Tenon's injection. Patients and surgeon's satisfaction, as well as the postoperative pain (the visual analogue scale, VAS) were investigated after operation. The contingency tables (including the Chi-square or Fisher's exact tests, when appropriate) and parametric analysis (the independent samples t test) were used for statistical analysis.

RESULTS

Complete akinesia (33.3% vs 4.8%, P=0.04), as well as the patients (85.7% vs 57.1%, P=0.04) and surgeon's satisfaction (87.5% vs 52.4%, P=0.02) were significantly more frequent in LH than in L group. The mean VAS was significantly lower in the same group (1.90±1.45 vs 3.00±1.55, P=0.04).

CONCLUSION

Addition of hyaluronidase to lidocaine solution for sub-Tenon's anesthesia significantly improves the ocular akinesia, enhances the intra-operative patients and surgeons' satisfaction, and attenuates the postoperative pain.

Angle-closure glaucoma-simpler answers to complex mechanisms: LXVI Edward Jackson Memorial Lecture

PURPOSE

To present evidence-based concepts that will explain mechanisms of angle-closure glaucoma.

DESIGN

Review of published evidence and personal perspective.

METHODS

Literature review and clinical research using imaging devices.

RESULTS

When the pupil dilates, the iris typically decreases its volume by losing extracellular fluid. Eyes with angle-closure lose less iris volume with pupil dilation, contributing to obstruction of the trabecular meshwork. Expansion of choroidal volume is a dynamic phenomenon and is a major risk factor in angle-closure. The mechanism of malignant glaucoma seems likely to result from poor conductivity of fluid through the vitreous, and past suggestions that it results from "misdirected" aqueous are not consistent with physiological principles.

CONCLUSIONS

Angle-closure and angle-closure glaucoma result from disturbed physiological mechanisms more than from simple anatomic measures, and future predictive testing can exploit knowledge of these factors.

Hyaluronidase reduces local anaesthetic volumes for sub-Tenon’s anaesthesia

BACKGROUND

Volumes of local anaesthetics for sub-Tenon's anaesthesia vary. Lower volumes produce less akinesia, whereas higher volumes increase chemosis and intra-ocular pressures. Hyaluronidase is often added to local anaesthetics to improve akinesia without increasing the volume of the injection, but this is controversial. This randomized, sequential allocation study examines the addition of hyaluronidase on the minimum local anaesthetic volume (MLAV) required for a sub-Tenon's block.

METHODS

Sixty-two patients having sub-Tenon's blocks for cataract surgery were randomized into two groups. The control group (n=31) received 2% w/v lidocaine and the study group (n=31) received 2% w/v lidocaine with hyaluronidase 15 IU ml(-1). Using parallel up-down sequential allocation from a 4 ml starting volume, the volumes in both groups were changed using a testing interval of 1 ml according to the quality of globe akinesia. The median effective local anaesthetic volume (MLAV) was calculated for both groups using probit regression.

RESULTS

The groups were similar for age, sex, and ocular axial length. The MLAV in the hyaluronidase group was 2.6 ml [95% confidence interval (CI), 2.1-3.l] and 6.4 ml (95% CI, 5.1-8.1) in the control group (P<0.002).

CONCLUSIONS

Hyaluronidase permits a significant 2.4-fold (95% CI, 1.8-3.4) reduction in MLAV for sub-Tenon's anaesthesia.

The effect of hyaluronidase on ultrasound-measured dispersal of local anaesthetic following sub-Tenon injection

PURPOSE

To determine by B-scan ultrasonography if the addition of hyaluronidase affects the dispersal of anaesthetic fluid after sub-Tenon's injection.

DESIGN

Single-centre prospective randomised double-blind study.

MATERIALS AND METHODS

We performed a trial in 19 patients who were randomised to receive 5 ml of lidocaine 2% alone, or with hyaluronidase 15 IU/ml. A pre-anaesthetic B-scan ultrasound was performed followed by a standard infero-nasal sub-Tenon's injection. Further B-scan ultrasound studies were performed at 1, 3, and 5 min recording depth of local anaesthetic fluid. Data was analysed with Fisher's exact test and Student's t-test where appropriate. Results were considered significant when P<0.05.

RESULTS

The maximum depth of local anaesthetic was significantly less in the hyaluronidase group than the control group at 3 and 5 min (0.79 vs1.65 mm, P-value 0.01 and 0.43 vs1.52 mm, P-value 0.002 respectively). There were no statistically significant differences in the akinesia, pain and surgical satisfaction scores between the two groups.

CONCLUSIONS

The addition of hyaluronidase significantly augments the dispersal of local anaesthetic fluid, as measured by B-scan ultrasonography.

Effect of hyaluronidase on ocular motility in sub-Tenon's anesthesia: randomized controlled trial

PURPOSE

To assess the effect of hyaluronidase additive on the onset and degree of ocular akinesia in sub-Tenon's anesthesia for cataract surgery.

SETTING

Routine cataract operating list.

METHOD

This double-blind randomized controlled study comprised 100 patients who had phacoemulsification cataract surgery. Patients were randomized to 1 of 2 groups. For sub-Tenon's anesthesia, Group A received 5 mL lignocaine 2% with sodium hyaluronidase 150 IU/mL and Group B, 5 mL plain lignocaine 2%. Akinesia was assessed by scoring movement in the 6 positions of gaze. Scores ranged from 0 (complete akinesia) to 3 (no akinesia). Movements were measured at 30 seconds and 1, 3, 5, and 10 minutes. Changes in motility scores were compared by the Mann-Whitney U test.

RESULTS

There was no significant difference in akinesia between the 2 groups 30 seconds after the injection (P =.224); however, at 1 and 3 minutes, Group A achieved significantly better akinesia than Group B (P =.003 and P =.023, respectively). The median score after 3 minutes was 3.5 (interquartile range 0 to 7.5) in Group A and 7.0 (interquartile range 2.5 to 10.0) in Group B. There was no significant difference between the groups at 5 and 10 minutes (P =.225 and P =.831, respectively).

CONCLUSIONS

The addition of hyaluronidase in sub-Tenon's anesthesia significantly improved the rapidity of the onset of akinesia. This benefit disappeared over time; after 5 minutes the akinesia observed in the group receiving hyaluronidase was similar to that in the group receiving lignocaine alone. Thus, there appears to be no benefit to adding hyaluronidase to the anesthetic solution in terms of final ocular akinesia.

The methodologic quality of clinical trials on regional anesthesia for cataract surgery

OBJECTIVE

To assess the methodologic quality of published randomized trials of regional anesthesia management strategies for cataract surgery.

DESIGN

Literature review and analysis.

METHOD

We performed a systematic search of the literature to identify all articles pertaining to regional anesthesia for cataract surgery on adults. Overall quality scores and scores for individual methodologic domains were based on the evaluations of two investigators experienced in methodologic research who independently reviewed all relevant articles using a quality abstraction form.

MAIN OUTCOME MEASURES

Study quality in each of five domains: representativeness, bias and confounding, intervention description, outcomes and follow-up, and statistical quality and interpretation.

RESULTS

Eighty-two randomized clinical trials were identified with a mean overall quality score of 44%. The mean domain scores ranged from 37% for representativeness to 58% for outcomes and follow-up. Forty percent or fewer studies received the maximum score for reporting the setting, the population, and the start and end dates; describing the inclusion and exclusion criteria; adequately randomizing subjects; and adequately masking individuals participating in the study. Key outcomes were often inadequately reported, including the distribution of patient-reported pain scores and the mean surgical time.

CONCLUSIONS

Greater attention to methodologic quality and detailed reporting of study results will improve the ability of readers to interpret the results of clinical trials assessing regional anesthesia for cataract surgery.

Synthesis of the literature on the effectiveness of regional anesthesia for cataract surgery

OBJECTIVE

To synthesize the findings of the randomized trials of regional anesthesia management strategies for cataract surgery.

DESIGN

Literature review and analysis.

METHOD

The authors performed a systematic search of the literature to identify all articles pertaining to regional anesthesia during cataract surgery on adults. One investigator abstracted the content of each article onto a custom-designed form. A second investigator corroborated the findings. The evidence supporting the anesthesia approaches was graded by consensus as good, fair, poor, or insufficient.

MAIN OUTCOME MEASURES

Evidence supporting the effectiveness of different forms of regional anesthesia.

RESULTS

There was good evidence that retrobulbar and peribulbar blocks provide equivalent akinesia and pain control during cataract surgery. Additionally, sub-Tenon's blocks were at least as effective as retrobulbar and peribulbar blocks. There was good evidence that retrobulbar block provides better pain control during surgery than topical anesthesia, and there was fair evidence that peribulbar block provides better pain control than topical anesthesia.

CONCLUSIONS

This synthesis of the literature demonstrates that currently used approaches to anesthesia management provide adequate pain control for successful cataract surgery, but there is some variation in the effectiveness of the most commonly used techniques. Data are needed on patient preferences to determine the optimal strategies for anesthesia management during cataract surgery.

Hyaluronidase as an adjuvant in bupivacaine-lidocaine mixture for retrobulbar/peribulbar block

Hyaluronidase 7.5 IU/mL added to the local anesthetic improves peribulbar block, but smaller concentrations have not been shown to be effective. In this prospective, double-blinded study, 714 consecutive ocular surgery patients were randomized into three groups: no hyaluronidase (n = 241), hyaluronidase 3.75 IU/mL (n = 244), and hyaluronidase 7.5 IU/mL (n = 229). Retrobulbar/peribulbar block was performed with two injections of a 1:1 mixture of bupivacaine 0.75% and lidocaine 2%, 6-8 mL. Patient data were collected on demographics, initial volume of local anesthetic, need for supplementary block, and akinesia of the anesthetized eye. When hyaluronidase was used (3.75 or 7.5 IU/mL), the initial block was sufficient and the anesthetized eye was akinetic significantly more often than in the group without hyaluronidase. The hyaluronidase groups (3.75 and 7.5 IU/mL) did not differ significantly in any respect. We conclude that the addition of hyaluronidase 3.75 or 7.5 IU/mL improved the success of the initial retrobulbar/peribulbar block and akinesia and reduced the need for supplementary block.

IMPLICATIONS

We conclude that the addition of hyaluronidase 3.75 or 7.5 IU/mL improved the success of the initial retrobulbar/peribulbar block and akinesia and reduced the need for supplementary block.

Na2B12H11SH (BSH) in combination with systemic hyaluronidase: a promising concept for boron neutron capture therapy for glioblastoma

OBJECTIVE

In an attempt to optimize the therapeutic potential of Na2B12H11SH (BSH) for boron neutron capture therapy for glioblastoma, the present study investigates the influence of systemically applied hyaluronidase (a glycolytic enzyme that enhances the activity of chemotherapeutic agents in different types of cancer) on the biodistribution of BSH in patients with glioblastoma.

METHODS

Patients in two uniform groups (Groups A and B, each of which had 10 patients with histologically confirmed glioblastomas) received BSH at a dose used in earlier therapeutic trials (75 mg/kg of body weight, administered intravenously) 24 hours before surgical debulkment. Patients from Group B received additional hyaluronidase (200,000 IU, administered intravenously) immediately before BSH infusion. Boron concentrations were analyzed by inductively coupled plasma-atomic emission spectroscopy.

RESULTS

The application of hyaluronidase was associated with a statistically significant improvement in the tumor (maximum)-to-blood concentration ratio of 1.83 (range, 0.68-3.67) compared with 1.31 (range, 0.8-1.78) with BSH alone. Moreover, with the use of hyaluronidase, there was a tendency for a higher maximal concentration in tumor (not statistically significant). Boron accumulation in glioblastoma tissue was highly selective in both groups, with tumor-to-healthy brain concentration ratios ranging from 6:1 to 20:1.

CONCLUSION

These preliminary data suggest that hyaluronidase improves BSH biodistribution and, consequently, the therapeutic potential of this boron carrier. This finding might be of clinical value in the future.

Retrobulbar anesthesia with and without adrenaline in extracapsular cataract surgery. A prospective, randomized, double-blind study

Seventy-five patients with senile cataract underwent a planned extracapsular cataract extraction. They were randomly divided into two groups, receiving retrobulbar anesthesia (4 ml lidocaine 2% and 250 IU hyaluronidase) with or without adrenaline. Patients in the adrenaline group had the lowest mean intraocular pressure after the retrobulbar injection (p < 0.02) and they required a shorter time of digital bulbar massage to reduce tension before surgery (p < 0.01). They also appeared to have a deeper anterior chamber during the first part of surgery, although the difference was not statistically significant. The duration of postoperative analgesia was significantly prolonged in patients receiving adrenaline. Different mechanisms explaining the effects of adrenaline in retrobulbar anesthesia are discussed.