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.

Apnea caused by retrobulbar anesthesia: A case report.

BACKGROUND: Apnea caused by retrobulbar anesthesia is a very rare but severe complication during ophthalmic surgery. CASE SUMMARY: We report a rare case of apnea caused by retrobulbar anesthesia, and emergency resuscitation was used. A 74-year-old female patient was diagnosed with rhegmatogenous retinal detachment in the right eye and planned to undergo vitrectomy under retrobulbar anesthesia. After the retrobulbar anesthesia in her right eye, she became unconscious and apneic. It was suggested that she had developed brainstem anesthesia. Assisted ventilation was initiated. Atropine 0.5 mg, epinephrine 1 mg, ephedrine 30 mg, and lipid emulsion were given. Five minutes later, her consciousness and breathing gradually returned, but with uncertain light perception in her right eye. Alprostadil 20 µg was given, and after 2 h her visual acuity resumed to the preoperative level. CONCLUSION: Brainstem anesthesia is a serious complication secondary to retrobulbar anesthesia. Medical staff should pay attention to the identification of brainstem anesthesia and be familiar with the emergency treatment for this complication.

Efficacy and safety of trans-sub-Tenon's retrobulbar anesthesia for pars plana vitrectomy: a randomized trial.

AIM: To compare the efficacy and safety of trans-sub-Tenon's ciliary nerve block anesthesia and transcutaneous retrobulbar anesthesia in patients undergoing pars plana vitrectomy (PPV). METHODS: A prospective, randomized, double-blinded clinical trial was conducted at Zhongda Hospital, Affiliated with Southeast University, from February 2021 to October 2021. Patients undergoing PPV were randomly allocated into two groups: the trans-sub-Tenon's anesthesia group (ST group) and the retrobulbar anesthesia group (RB group) in the ratio of 1:1. The ST group received 2 ml ropivacaine through the Tenon capsule to the retrobulbar space, while the RB group received 2 ml ropivacaine via transcutaneous retrobulbar injection. Visual analog score (VAS) was used to evaluate pain during the whole process, including during anesthesia implementation, intraoperatively and on the first day after the operation. Movement evaluation (Brahma scores) and anesthesia-related complications were also noted. RESULTS: Finally, a total of 120 patients were included in the study (60 in the ST group and 60 in the RB group). There were no significant differences in baseline patient characteristics or surgical features between the two groups. The VAS pain scores for anesthesia implementation were 0.52 ± 0.47 in the ST group and 1.83 ± 0.87 in the RB group (P < 0.001). The VAS scores during the operation were 0.53 ± 0.49 in the ST group and 1.48 ± 1.02 in the RB group (P < 0.001) and those on the first day after the operation were 0.37 ± 0.38 in the ST group and 0.81 ± 0.80 in the RB group (P = 0.002). No patients required supplemental intravenous anesthesia intraoperatively. The Brahma movement scores were 0.70 ± 1.64 in the ST group (scores ranging from 0 to 8) and 2.38 ± 3.15 in the RB group (ranging from 0 to 12) (P = 0.001). Forty-two patients in each group received laser photocoagulation during surgery. Fifteen patients (36%) in the ST group could not see the flashes of the laser, compared to 8 patients (19%) in the RB group (P = 0.087). No serious sight-threatening or life-threatening complications related to anesthesia were observed in either group. CONCLUSIONS: For PPV, trans-sub-Tenon's ciliary nerve block anesthesia was more effective in controlling pain than transcutaneous retrobulbar anesthesia during the whole surgery process, including during anesthesia implementation, intraoperatively and on the first day after the operation. Additionally, it could achieve better effect of akinesia and was relatively safe. Trans-sub-Tenon's anesthesia could be considered an alternative form of local anesthesia during vitreoretinal procedures. TRIAL REGISTRATION: The study protocol has been registered at ChiCTR.org.cn on February 2021 under the number ChiCTR2100043109 .

3D-Printed Ophthalmic-Retrobulbar-Anesthesia Simulator: Mimicking Anatomical Structures and Providing Tactile Sensations.

Objective: A simulator for retrobulbar anesthesia administration mimicking the orbital anatomy and providing tactile sensation is proposed. Methods: The production process involves 3D modeling of anatomical structures on the basis of computerized tomography (CT) images, printing the models using a 3D printer, and casting the silicone. Twenty ophthalmologists administered retrobulbar anesthesia using the simulator with four different ocular axial lengths (including extreme myopes); the position of the needle tip was evaluated. The effectiveness of this simulator for training was also surveyed. Results: The proportions of the final location of the needle tip were 59.25%, 36.25%, and 4.5% for the retrobulbar space, peribulbar space, and intraocular space, respectively. Experienced ophthalmologists showed lower complication rates than residents (0.5% vs 8.5%, [Formula: see text]) and agreed that this simulator will help young ophthalmologists advance their anesthesia-administering skills. Discussion/Conclusion: The 3D-printered simulator for retrobulbar anesthesia was produced and performance was verified. The technology could be used to simulate critical orbital anatomic features and could be used as a training tool for resident ophthalmologists.

Inadvertent globe penetration during retrobulbar anesthesia: A case report.

BACKGROUND: To report the possible reasons for needle perforation and complications related to perforation, as well as the clinical management of subretinal hemorrhage (SRH) during retrobulbar injection. CASE SUMMARY: A 65-year-old female was scheduled to undergo pars plana vitrectomy (PPV) in her left eye for rhegmatogenous retinal detachment (RRD). During retrobulbar anesthesia, needle perforation of the globe occurred. Massive SRH in the inferotemporal quadrant together with vitreous hemorrhage were observed. The patient underwent PPV combined with retinotomy for removal of the massive SRH. After earlier surgical intervention, successful reattachment of the retina was achieved. CONCLUSION: Inadvertent globe penetration during retrobulbar anesthesia is associated with a poor prognosis and may result in blindness. Timely detection and earlier intervention may be beneficial.

A New Two-Step Anesthesia for 23- or 25-Gauge Vitrectomy Surgery: A Prospective, Randomized Clinical Trial.

OBJECTIVE: To investigate the safety and efficacy of topical anesthesia combined with subconjunctival anesthesia (termed two-step anesthesia) for 23- or 25-gauge pars plana vitrectomy or other posterior segment surgery. METHODS: Patients (n = 90) requiring 23-/25-gauge vitrectomy or other posterior segment surgery were randomized into 3 groups. Group 1 received peribulbar anesthesia, group 2 received retrobulbar anesthesia and group 3 received two-step anesthesia. A 5-point visual analog pain scale (VAPS) was used to measure self-report of patient pain. Complications were recorded for subsequent analysis. RESULTS: VAPS scores for overall intraoperative pain ranged from 0 to 3 (1.07 ± 1.07) in group 1, from 0 to 2 (0.69 ± 0.93) in group 2 and from 0 to 3 (1.06 ± 0.98) in group 3. Assessment of surgeon discomfort score ranged from 0 to 2 (0.31 ± 0.66) in group 1, from 0 to 3 (0.38 ± 0.82) in group 2 and from 0 to 2 (0.47 ± 0.62) in group 3. Both scores reveal no significant difference among the 3 groups. While there were no complications noted in group 1, there was an ocular perforation in group 2. Additionally, there were no complications in group 3 related to the anesthetic technique. CONCLUSIONS: Results suggest that two-step anesthesia is a safe and effective anesthetic approach for selected patients undergoing 23- or 25-gauge pars plana vitrectomy or other posterior segment surgeries. It may offer a viable alternative to peribulbar anesthesia and retrobulbar anesthesia for carefully selected 23- or 25-gauge cannular-access ocular surgeries.

Evaluating the effectiveness of localized sub-Tenon's anesthesia in 23-gauge vitreoretinal surgery.

PURPOSE: To evaluate the effectiveness of localized sub-Tenon's anesthesia for pain control during 23-gauge vitreoretinal surgery. METHODS: Eighty patients were randomly divided into two groups as localized sub-Tenon's (group 1, n = 41) and retrobulbar (group 2, n = 39) anesthesia groups. In group 1, a small volume of anesthetic was injected into the sub-Tenon's capsules at the trocar entry sites. The 23-gauge vitreoretinal surgery was performed in all patients. In both groups, the pain levels during the surgical steps were evaluated using the visual analog pain scale. RESULTS: Patients in group 1 experienced less pain than group 2 patients did during placement of the trocars and scleral depression (p = 0.041, p = 0.029). Pain during laser photocoagulation was higher in group 1 (p = 0.008). There was no serious complication due to anesthesia or surgery. CONCLUSION: Localized sub-Tenon's anesthesia is as effective as retrobulbar anesthesia in many steps of vitreoretinal surgery for providing pain control. It can be considered an alternative form of local anesthesia.

Comparison of analgesia and akinesia between sub-Tenon's capsule anesthesia and trans-Tenon's capsule retrobulbar anesthesia in vitrectomy.

OBJECTIVES: We compared the effects of sub-Tenon's capsule anesthesia (STA) and trans-Tenon's capsule retrobulbar anesthesia (TTRBA) in 68 patients with epiretinal membrane. METHODS: Either STA or TTRBA was induced with 3 mL of lidocaine (2%) before vitrectomy combined with phacoemulsification and aspiration (phacovitrectomy). Akinesia was evaluated by range of eye movement (ROEM) in upward, downward, nasal, and temporal directions at 4, 10, and 30 minutes after injection. Analgesia was evaluated with a visual analogue pain score, which ranged from 0 to 10. RESULTS: The mean cumulative ROEMs were 1.44±1.02 corneal diameters (CDs) at 4 minutes, 0.55±0.76 CDs at 10 minutes, and 0.26±0.33 CDs at 30 minutes in patients who received STA; these values were 0.39±0.35 CDs at 4 minutes, 0.22±0.30 CDs at 10 minutes, and 0.13±0.29 CDs at 30 minutes in patients who received TTRBA. At both 4 and 10 minutes, the cumulative ROEMs in all directions, as well as the temporal ROEMs, were significantly larger in patients who received STA than in patients who received TTRBA. Pain scores did not significantly differ between groups at any time point. CONCLUSIONS: STA and TTRBA produced identical degrees of analgesia, but akinesia was slower in patients who received STA. TTRBA might be preferable for patients undergoing brief vitrectomy.

[Strabismus and oculomotor disorders induced by injection anesthesia for cataract surgery]. / Kosoglazie i glazodvigatel'nye narusheniya, indutsirovannye in"ektsionnoi anesteziei v khirurgii katarakty.

PURPOSE: To analyze diagnostic and treatment outcomes in patients with strabismus and oculomotor disorders induced by injection anesthesia for cataract surgery. MATERIAL AND METHODS: The study included 11 patients (7 women and 4 men) aged 61 to 85 years (the mean age of 66±7.1 years) who complained of diplopia in the early post-op period after cataract phacoemulsification and elastic IOL implantation under retrobulbar anesthesia. Prior to further surgical treatment, all of the patients underwent functional multispiral computer tomography of the orbits. Prismatic spectacle correction was also used independently or in addition to surgical treatment. RESULTS: Eight out of eleven patients underwent one- or two-step surgical treatment (3 and 5 cases, respectively). In 2 patients, hypotropia did not exceed 10 prism diopters, and thus, diplopia could be compensated with prismatic spectacle correction alone. In 5 cases, binocular vision was achieved throughout the whole field of gaze. In 3 cases, surgical treatment enabled elimination of heterotropia in the primary gaze and compensation of diplopia within a radius of 40º from the center of gaze and within the entire horizontal range of eye-movement in the downward gaze. The limitation of ocular mobility decreased from 2.36 to 0.55 points leading to an associated decrease in the area of binocular diplopia - from 98% to 29%. In one case, spectacle occlusion was used. CONCLUSION: The inferior rectus restriction is the morphological substrate of anatomical and functional changes induced by retrobulbar anesthesia. As treatment options for restrictive vertical strabismus and binocular diplopia, both surgical (extraocular muscle surgery) and optical (prismatic correction, occlusion) methods should be considered.

The effect of retrobulbar anesthesia for cataract surgery on the retinal nerve fiber layer thickness.

OBJECTIVE: The aim of this study was to evaluate the effect retrobulbar and topical anesthesia on optic nerve by measuring retinal nerve fiber layer (RNFL) thickness before and after phacoemulsification cataract surgery using optical coherence tomography (OCT). METHODS: A total of 126 eyes of 108 patients were included in the study. Retrobulbar anesthesia was used in 61 eyes of 53 patients, and topical anesthesia was used in 65 eyes of 55 patients. OCT scans were done 1 week before the surgery and 4 weeks after surgery, and the results were evaluated. RESULTS: The average RNFL thickness increased postoperatively in both groups (p < 0.001 for topical anesthesia group and p = 0.001 for retrobulbar anesthesia group). The preoperative and postoperative average and quadrant RNFL thickness and the change in RNFL thickness were not significantly different between the two anesthesia groups (p > 0.05). CONCLUSION: Our results suggest that retrobulbar anesthesia has no unfavorable effect on the retinal nerve fiber layer.

A review of ophthalmic local and regional anesthesia in dogs and cats.

OBJECTIVE: Orbital and globe surgeries are commonly performed in companion animals and are considered to cause moderate to severe pain. Regional anesthesia techniques can provide complete sensory blockade, analgesia for painful procedures and improve surgical conditions. The purpose of this review is to summarize local and regional anesthesia techniques for ophthalmic surgery in dogs and cats with emphasis on veterinary publications in the past 12 years. DATABASES USED: Review of the literature was conducted using PubMed and Google Scholar. The search terms were 'ophthalmic regional anesthesia', 'retrobulbar anesthesia', 'peribulbar anesthesia', 'sub-Tenon's anesthesia', 'intracameral anesthesia', 'eye infiltration', 'dogs' and 'cats'. Further studies and reports were obtained from the reference lists of the retrieved papers. In addition, related veterinary anatomy, ophthalmology and regional anesthesia books were reviewed. CONCLUSIONS: Reported techniques include regional techniques such as retrobulbar anesthesia, peribulbar anesthesia and sub-Tenon's anesthesia, and local techniques such as eyelid and conjunctival infiltration, intracameral anesthesia, splash block and insertion of intraorbital absorbable gelatin sponge infused with local anesthetic. Administration guidelines, indications and contraindications, and complications of each technique are discussed. Regional anesthesia techniques were reported to be effective during ophthalmic surgeries and are recommended for use as part of the anesthetic regimen and pain management in animals. However, the veterinary literature is still lacking controlled clinical trials and adverse events reports; therefore, there is very little evidence for choosing one technique over another.

Retrobulbar vs peribulbar regional anesthesia techniques using bupivacaine in dogs.

OBJECTIVE: To compare the effectiveness of retrobulbar anesthesia (RBA) and peribulbar anesthesia (PBA) in dogs. ANIMAL STUDIED: Six adult mixed-breed dogs (18-24 kg). PROCEDURES: In a randomized, masked, crossover trial with a 10-day washout period, each dog was sedated with intravenously administered dexmedetomidine and administered 0.5% bupivacaine:iopamidol (4:1) as RBA (2 mL via a ventrolateral site) or PBA (5 mL divided equally between ventrolateral and dorsomedial sites). The contralateral eye acted as control. Injectate distribution was evaluated by computed tomography. Following intramuscularly administered atipamezole, corneal and periocular skin sensation, intraocular pressure (IOP), and ocular reflexes, and appearance were evaluated for 24 hours. Comparisons were performed with mixed-effects linear regression (IOP) or the exact Wilcoxon signed rank test (scores). Significance was set at P ≤ .05. RESULTS: Injectate distribution was intraconal in 2/6 RBA- and 4/6 PBA-injected eyes. Eyes undergoing PBA had significantly reduced lateral, ventral, and dorsal periocular skin sensation for 2-3 hours, and significantly reduced corneal sensitivity for 4 hours, relative to control eyes. Chemosis and exophthalmos occurred in 33%-40% of eyes undergoing RBA and 83%-100% eyes undergoing PBA but resolved within 14 hours. Anterior uveitis developed in 2/6 and 1/6 eyes of RBA and PBA, respectively, of them corneal ulcer developed in one eye of each treatment. Both resolved 1-3 days following medical treatment. CONCLUSIONS: Peribulbar injection produced notable anesthesia more reliably than did retrobulbar injection. Both techniques may produce adverse effects, although the uveitis/ulcer could have resulted from the contrast agent used.

Two Case Reports of a Purtscher-like Retinopathy Occurring after Retrobulbar Anesthesia

PURPOSE: Although there are significant risks, retrobulbar anesthesia is commonly used for eye surgery. We report two cases of Purtscher-like retinopathy, a rare complication. CASE SUMMARY: (Case 1) A 76-year-old female visited our hospital because of decreased vision. She underwent right cataract surgery with retrobulbar anesthesia. After 7 days, she had decreased visual acuity (VA) and a constricted visual field. Multiple white spots and cotton wool spots around the optic nerve and post pole, macular edema (ME), and subretinal fluid (SRF) were found using a fundus examination. A non-perfusion area and staining of the vascular wall were seen using fluorescence angiography. Although carotid arterial angiography, thrombolysis, and intravenous injection of high-dose steroids were performed, the ME and SRF persisted. After intravitreal aflibercept was injected twice (2-month interval), the ME and SRF decreased and remained stable. (Case 2) A 61-year-old male underwent left cataract surgery with retrobulbar anesthesia. After anesthesia, the VA of the left eye was 10 cm finger count. The fundus examination showed multiple hemorrhage blots and retinal hemorrhages, and hyperfluorescence around the optic nerve and post pole; vascular wall staining revealed a Purtscher-like retinopathy. Left carotid arterial angiography, thrombolysis, and intravenous injection of high-dose steroids were then performed. After treatment, the VA of the left eye, ME, and SRF were improved at the 4-month follow-up. CONCLUSIONS: We report rare complications of retrobulbar anesthesia, with active and timely treatment having a positive impact on the visual prognosis.

Displacement of crystalline lens into the sub-conjunctival space following periocular anesthesia.

A 65-year-old female presented with loss of vision and a mass in her right eye after periocular anaesthesia for cataract surgery in a camp. She was found to have a nasal subconjunctival mass, which was confirmed to contain the crystalline lens after surgical exploration, along with a superior perilimbal suspected scleral rupture. There was accompanying vitreous haemorrhage, retinal detachment and subretinal haemorrhage that was managed by pars plana vitrectomy. Post operatively, she achieved a best corrected visual acuity of 20/80 that was maintained till 6 months follow up. Globe rupture and subconjunctival lens extrusion in the setting of inadvertent globe penetration during periocular anesthesia is a rare complication. In the absence of medical records pertaining to the primary event, this clinical presentation posed a diagnostic challenge. Timely and appropriate management led to an acceptable visual and anatomical outcome in this unfortunate and devastating scenario.

A comparison between topical and retrobulbar anesthesia in 27-gauge vitrectomy for vitreous floaters: a randomized controlled trial.

BACKGROUND: To compare the safety and efficacy of topical anesthesia versus retrobulbar anesthesia in 27-gauge pars plana vitrectomy (PPV) for vitreous floaters. METHODS: 30 patients with vitreous floaters were randomized into Group T (topical anesthesia, proparacaine eye drop) and Group R (retrobulbar anesthesia), and underwent 27-gauge PPV. A 5-point visual analogue pain scale (VAPS) was used to assess patients' pain experience of anesthesia and surgery procedure (during surgery, 2 h and 1 day after surgery). RESULTS: The VAPS of anesthesia procedure was 1.27 ± 0.59 for patients in Group R, while it was all 0 for patients in Group T (p < 0.001). There was no significant difference for VAPS during surgery (Group T: 1.13 ± 0.74, Group R: 0.67 ± 0.62, p = 0.67), 2 h (Group T: 0.80 ± 1.01, Group R: 0.67 ± 0.62, p = 0.67) and 1 day (Group T: 0.20 ± 0.41, Group R: 0.27 ± 0.46, p = 0.68) after surgery between these two groups. Only one patient (6.7%) in Group T required additional topical anesthesia during the surgery. Most of the patients reported the pain experience came from initial trocar insertion in both groups. None of the patients required post operative analgesia in both groups. No intraoperative or postoperative complications were noted in both groups. CONCLUSION: This study suggested that topical anesthesia is a safe and effective anesthetic approach for patients with floaters who underwent 27-gauge PPV. TRIAL REGISTRATION: ClinicalTrials.gov NCT03049163 . Registered 8 February 2017.

Evaluation of ocular perforation during retrobulbar block using high-resolution spectral domain-optical coherence tomography and optical coherence tomography angiography.

INTRODUCTION: This article reports a case of ocular perforation during a retrobulbar block in a patient who underwent scleral buckle for retinal detachment. METHODS: Sterile air was immediately injected into the vitreous cavity to restore intraocular pressure and the scleral buckle operation was quickly finished. One week later, a laser retinopexy was performed on the two retinal holes that were outside the foveal area. After 6 months, spectral domain-optical coherence tomography and optical coherence tomography angiography were performed on the perforated wall centered on the exit hole area. RESULTS: The visual acuity was maintained 20/20 and the retina was totally attached. Spectral domain-optical coherence tomography showed a localized interruption of inner retina, retinal pigment epithelium, and choroid, with a higher posterior reflectivity in correspondence with the sclera. Optical coherence tomography angiography was able to detect atrophic alterations in the choroidal slab with a good visualization of large and rarefied choroidal vessels due to lack of retinal pigment epithelium and choriocapillaris. CONCLUSION: When ocular perforation by a needle is outside the foveal area and when there is an early awareness of the perforation, the complications may be avoided, and we could observe a good final visual acuity result. Furthermore, using spectral domain-optical coherence tomography and optical coherence tomography angiography, we could observe the perforated eyeball wall and study the effects of a 25-gauge needle perforation in the retinal and choroidal blood stream.

Sub-Tenon's anesthesia for canine cataract surgery.

OBJECTIVE: To test a sub-Tenon's anesthesia technique in dogs as an alternative to systemic neuromuscular blockade to aid in canine cataract surgery under general anesthesia. PROCEDURES: A prospective controlled clinical study was performed involving 12 dogs undergoing bilateral cataract surgery under general anesthesia. One eye was randomly assigned to have phacoemulsification and prosthetic lens implantation performed with sub-Tenon's anesthesia (STA), and the control eye had surgery performed with systemic neuromuscular blockade (NMB). Intraocular pressure (IOP) was measured immediately before and after STA administration. Globe position, globe rotation, pupillary dilation, and vitreal expansion were assessed for both STA and NMB eyes during surgery. RESULTS: Sub-Tenon's anesthesia produced a globe position suitable for cataract surgery with the degree of vitreal expansion not significantly different to control NMB eyes. STA produced greater anterior globe displacement than NMB in all cases. STA had no significant effect on IOP. CONCLUSION: Sub-Tenon's anesthesia was an effective alternative to systemic neuromuscular blockade for canine cataract surgery and may be beneficial for surgical exposure in deep orbited breeds.

Subconjunctival hemorrhage and vision loss after regional ocular anesthesia.

PURPOSE: To report two cases of retinal vascular occlusion and associated subconjunctival hemorrhage in needle optic nerve injury during local bulbar anesthesia. METHODS: Surgical records of these two subjects who presented with acute vision loss after cataract extraction were studied, and systemic workup and ocular imaging were carried out to establish the cause. RESULTS: Computerized tomography showed evidence of optic nerve injury. CONCLUSION: Subconjunctival hemorrhage could be an associated clinical finding in hypodermic needle injury-related retinal vascular occlusion during ocular anesthesia.

Optimal Dose of Dexmedetomidine Retrobulbar Anesthesia during Phacoemulsification Cataract Surgery.

BACKGROUND: The cataract surgery anesthesia should be to make the procedure as safe and as satisfactory as possible for all concerned. The recent progress in anesthesia and surgery now allow cataract extraction to be done with minimal physiological changes to the patient. We aimed in the study to compare between two different doses of dexmedetomidine combined with lidocaine and bupivacaine during retrobulbar anesthesia for cataract extraction by phacoemulsification. MATERIALS AND METHODS: This study was done on forty patients with cataract. The patients were enrolled in two groups: Group (A):Twenty patients were received 1.5 ml 2% lidocaine + 1.5 ml 0.5% bupivacaine + 0.25 µg/kg of dexmedetomidine and Group (B): Twenty patients were received 1.5 ml 2% lidocaine + 1.5 ml 0.5% bupivacaine + 0.5 µg/kg of dexmedetomidine. RESULTS: The globe anesthesia duration, globe, and lid akinesia were significantly longer in the Group B than in the Group A (P < 0.05). Intraocular pressure decreased through the first 15 min after anesthesia in the two groups, and the changes were not significant between the two groups but highly significant in every group when compared to its baseline reading. As regards the conscious level in the two groups, there was a significant difference (P < 0.001). Group A is higher regarding score 2 and 3, and Group B higher in score 4. CONCLUSIONS: We concluded that dexmedetomidine 0.25 µg/kg, when added to retrobulbar block for cataract surgery, will significantly increase the duration of retrobulbar block and improve both the surgeon and the patient satisfaction.

A comparison of retrobulbar and two peribulbar regional anesthetic techniques in dog cadavers.

OBJECTIVE: To compare injectate distribution and likelihood of regional anesthesia to the orbit following retrobulbar (RB) or peribulbar (PB) injections in dog cadavers. STUDY DESIGN: Randomized, masked study. ANIMALS: Twenty-four dog cadavers (aged 5.5-17 years, 2.0-36.3 kg). METHODS: Orbits underwent one of three injection techniques with bupivacaine 0.5% and iohexol (1:1): ventrolateral RB injection (1-2 mL; 15 orbits), medial canthal PB injection (2-8 mL; PB-1; 16 orbits), or dorsomedial and ventrolateral PB injections (each 1-4 mL; PB-2; 16 orbits). The likelihood of successful regional anesthesia was estimated based on computed tomographic images scored for injectate volume of distribution at the base and within the extraocular muscle cone (EOMC), and injectate distribution around the optic nerve. Intraocular pressure (IOP) was measured before and after injections. Mixed-effects linear regression with post hoc Bonferroni contrast adjustments was performed. Significance was set at 0.05. RESULTS: A difference in injectate volume of distribution within or at the base of the EOMC was not detected among groups. The median optic nerve circumference of injectate distribution was significantly higher in the RB injected group than in the PB-2 group. Injectate distribution following RB, PB-1 and PB-2 injections was graded as likely to provide regional anesthesia within the EOMC in 40%, 19% and 31% of eyes, and at the EOMC base in 60%, 63% and 50% of eyes, respectively. The probability of likelihood to provide regional anesthesia was lower in dogs of higher body weights. The IOP was significantly higher than baseline following PB-1 (18 ± 14 mmHg) and in comparison with RB (2 ± 3 mmHg), but not different from PB-2 injection (10 ± 11 mmHg). CONCLUSIONS AND CLINICAL RELEVANCE: None of the techniques reliably produced 'successful' injectate distribution based on this study's definitions; however, clinical assessment of anesthetic success is required.