Cytotoxicity of Lidocaine or Bupivacaine on Corneal Endothelial Cells in a Rabbit Model

Safety of an Intracameral Fixed Combination for Mydriasis and Intraocular Anaesthesia During Cataract Surgery

Purpose

To compare the safety of a standardized, commercially available intracameral combination of mydriatics and anesthetic (ICMA) with a reference topical mydriatic regimen for cataract surgery.

Patients and Methods

The safety results from two international, randomized, controlled clinical studies were combined to compare ICMA at the beginning of cataract surgery (ICMA group) to the reference topical mydriatic regimen (reference group). Data were collected on ocular and systemic adverse events, corneal and anterior chamber examination, endothelial cell density, retinal thickness and visual acuity. Analysis was performed on a pooled safety set from both studies, preoperatively and up to 1 month postoperatively.

Results

342 patients received ICMA and 318 the reference topical regimen. Ocular adverse events were reported in 17.0% of patients in the ICMA group and 18.6% in the reference group. No difference was shown between groups in endothelial cell density (2208 ± 498 cells/mm2 for ICMA group versus 2241 ± 513 cells/mm2 for the reference group; p=0.547) and retinal thickness (change from baseline less than 50 µm in 94.7% versus 95.0% of patients, respectively) at 1 month postoperatively. At 1-day post-surgery, less patients in the ICMA group had moderate or severe (Grades 2 and 3) superficial punctate corneal staining (3.9% versus 7.0% for the reference group; p=0.064). Postoperatively, some ocular symptoms were also less frequently reported in the ICMA group. Best-corrected visual acuity increased in 96.0% of patients in the ICMA group and 95.8% in the reference group at 1 month.

Conclusion

ICMA injection at the beginning of cataract surgery was demonstrated to be safe and may also provide perioperative and postoperative advantages over the standard topical mydriatic regimen.

Topical pain control for corneal abrasions: A systematic review and meta-analysis

OBJECTIVES

Corneal abrasions are common ophthalmic presentations to emergency departments. Among emergency physicians and ophthalmologists, there are highly variable practice patterns with regard to management of resultant pain and discomfort. The goal of this study was to review and analyze the efficacy and safety of topical pain therapies for corneal abrasions, including topical anesthetics, nonsteroidal anti-inflammatory drugs (NSAIDs), cycloplegics, steroids, pressure patching, and the use of a bandage contact lens (BCL).

METHODS

The review followed the Preferred Reporting Items for Systematic Review and Meta-analysis (PRISMA) guidelines. The protocol was established a priori and published on PROSPERO (CRD42020201288). MEDLINE, EMBASE, CENTRAL, and Web of Science were searched until December 31, 2020. Primary studies comparing topical pain therapies to another therapy or control were included. Primary outcomes included percentage of corneal abrasions healed at 24, 48, and 72 hours, as well as pain control at 24 and 48 hours. Secondary outcomes included use of oral analgesia and incidence of complications. Risk of bias was assessed using validated tools. Quality of evidence was assessed using the GRADE methodology.

RESULTS

Overall, 33 studies (31 randomized controlled trials [RCTs], two cohort studies) comprising 4,167 patients with corneal abrasions were analyzed. Only the data for topical NSAIDs were of adequate evidence from which to draw conclusions; topical NSAIDs demonstrated significantly reduced pain scores at 24 hours (standardized mean differences [SMD] -0.69, 95% CI = -0.98 to -0.41) and 48 hours (SMD = -0.56, 95% CI = -1.02 to -0.10) as well as 53% (95% CI = 34% to 67%) lower oral analgesia use compared to control. Based on available data, topical anesthetics, cycloplegics, patching, and the use of a BCL did not result in any significant difference in pain scores or use of oral analgesia, while no studies examined topical steroids. No interventions resulted in healing delays or significantly higher rates of complications compared to controls.

CONCLUSIONS

There was strong evidence to support that topical NSAIDs reduce pain associated with corneal abrasions in the first 48 hours and the need for oral analgesia. The existing evidence was insufficient to support or refute the use of topical anesthetics, cycloplegics, steroids, or BCL for pain control in corneal abrasions. Pressure patching was ineffective at pain reduction and may increase the risk of complications. Delays in healing or other complications were not significantly different between any intervention or control for simple, uncomplicated corneal abrasions; however, larger RCTs are required to identify any differences in rare complications.

Comparative Analysis of Different Local Anesthetic Solutions Available in Market: An In Vitro and Clinical Study

OBJECTIVES

 The study aimed to evaluate and compare various commercially available local anesthetic solutions.

MATERIALS AND METHODS

 A total of 150 commercially available local anesthetic cartridges of similar composition (2% lidocaine with epinephrine 1:100,000) were randomly collected and divided into 3 groups. The designations of groups were selected from their product names such that each group consisted of 60 cartridges. Group S (Septodont, France) Group M (Medicaine, Korea) and Group H (HD-Caine, Pakistan). The samples were divided into five sub-groups, each consisting of 10 cartridges from each group to investigate each parameter.

RESULTS

 The acquired data was statistically analyzed and compared (using SPSS version 12). Compositional analysis revealed a non-significant (P>0.05) difference when the three Groups were compared with standard lidocaine and epinephrine solutions. The mean pH values of samples from group S, M and H respectively fell within the range of pH values of commercially available solutions. Non-significant difference in EPT values of Group S and H was found when efficacy was compared (p = 0.3), however a significant difference (p < 0.01) was observed in contrast to Group M. Anti-bacterial activity was observed in all the group and a non-significant difference in cell viability values of Group S and M was found (p = 0.6), while the difference was significant in comparison to Group H.

CONCLUSION

 Within the limitations of these investigations, it appears that the properties of different manufacturers fall within the recommended ranges as mentioned in literature and do not appear to be statistically different in the variables we have tested.

Wire Myography for Continuous Estimation of the Optimal Concentration of Topical Lidocaine as a Vasodilator in Microsurgery

BACKGROUND

 Intraoperative vasospasm during reconstructive microvascular surgery is often unpredictable and may lead to devastating flap loss. Therefore, various vasodilators are used in reconstructive microsurgery to prevent and relieve vasospasm. Lidocaine is a vasodilator commonly used in microvascular surgery. Although many reports have described its in vitro and in vivo concentration-dependent vasodilatory effects, limited studies have examined the pharmacological effects of lidocaine on blood vessels in terms of persistence and titer.

METHODS

 In this study, the vasodilatory effect of lidocaine was examined by using the wire myograph system. Abdominal aortas were harvested from female rats, sliced into rings of 1-mm thickness, and mounted in the wire myograph system. Next, 10, 5, 2, and 1% lidocaine solutions were applied to the artery, and the change in vasodilation force, persistence of the force, and time required to reach equilibrium were measured.

RESULTS

 The vasodilatory effect was confirmed in all groups following lidocaine treatment. Although strong vasodilation was observed in the 10% lidocaine group, it was accompanied by irreversible degeneration of the artery. Vasodilation in the 1% lidocaine group was weaker than that in the other groups 500 seconds after lidocaine addition (p < 0.05). Between the 5 and 2% lidocaine groups, 5% lidocaine showed a stronger vasodilatory effect 400 to 600 seconds after lidocaine addition (p < 0.01); however, there was no significant difference in these groups after 700 seconds. Additionally, there was no difference in the time required for the relaxation force to reach equilibrium among the 5, 2, and 1% lidocaine groups.

CONCLUSION

 Although our study confirmed the dose-dependent vasodilatory effect of lidocaine, 5% lidocaine showed the best vasodilatory effect and continuity with minimal irreversible changes in the arterial tissue.

Short-Term Topical Tetracaine Is Highly Efficacious for the Treatment of Pain Caused by Corneal Abrasions: A Double-Blind, Randomized Clinical Trial

STUDY OBJECTIVE

The objective of this study is to show that patients with corneal abrasions would experience more pain relief with short-term topical tetracaine than placebo.

METHODS

The study was a prospective, double-blind, randomized trial of tetracaine versus placebo set in the emergency department (ED). A total of 118 adults who presented with uncomplicated corneal abrasions were included and randomized. The intervention was either topical tetracaine or placebo applied every 30 minutes as needed for 24 hours. The primary outcome was the overall numeric rating scale pain score measured at the 24- to 48-hour ED follow-up examination.

RESULTS

One hundred eleven patients were included in the final analysis, 56 in the tetracaine group and 55 in the placebo group. At the 24- to 48-hour follow-up, the overall numeric rating scale pain score after use of the study drops was significantly lower in the tetracaine group (1) versus placebo group (8) (Δ7; 95% confidence interval 6 to 8). Patients in the tetracaine group used less hydrocodone than those in the placebo group. The complication rates between the 2 groups were similar.

CONCLUSION

Short-term topical tetracaine is an efficacious analgesic for acute corneal abrasions, is associated with less hydrocodone use compared with placebo, and was found to be safe in this sample.

Emergency medicine myths and misconceptions: evaluating the evidence

Medical reversal is common, with rates of reversal of practices that were considered standard of care as high as 40%. Unfortunately, many standards of care are never tested, but instead are often promoted based on pathophysiological explanations or simply being long-established practices. Much of medical practice is based on dogma: a set of principles laid down by authority as incontrovertibly true. This article evaluates four commonly taught dogmatic practices in emergency medicine to determine if they are supported by the medical literature or are instead myths and misconceptions: (1) topical anaesthetics inhibit corneal healing, (2) treatment of myocardial infarction is MONA (morphine, oxygen, nitrates, aspirin), (3) children do not get sprains because their ligaments are stronger than bone, and (4) vagal manoeuvres for supraventricular tachycardia never work in adults. Medicine is changing all the time, and the best way to ensure that one is practicing medicine that is accurate, up to date and not prone to being reversed is to always be sceptical and to learn how to read and interpret the medical literature.

Sodium Ferulate Attenuates Lidocaine-Induced Corneal Endothelial Impairment

The introduction of intracameral anaesthesia by injection of lidocaine has become popular in cataract surgery for its inherent potency, rapid onset, tissue penetration, and efficiency. However, intracameral lidocaine causes corneal thickening, opacification, and corneal endothelial cell loss. Herein, we investigated the effects of lidocaine combined with sodium ferulate, an antioxidant with antiapoptotic and anti-inflammatory properties, on lidocaine-induced damage of corneal endothelia with in vitro experiment of morphological changes and cell viability of cultured human corneal endothelial cells and in vivo investigation of corneal endothelial cell density and central corneal thickness of cat eyes. Our finding indicates that sodium ferulate from 25 to 200 mg/L significantly reduced 2 g/L lidocaine-induced toxicity to human corneal endothelial cells, and 50 mg/L sodium ferulate recovered the damaged human corneal endothelial cells to normal growth status. Furthermore, 100 mg/L sodium ferulate significantly inhibited lidocaine-induced corneal endothelial cell loss and corneal thickening in cat eyes. In conclusion, sodium ferulate protects human corneal endothelial cells from lidocaine-induced cytotoxicity and attenuates corneal endothelial cell loss and central corneal thickening of cat eyes after intracameral injection with lidocaine. It is likely that the antioxidant effect of sodium ferulate reduces the cytotoxic and inflammatory corneal reaction during intracameral anaesthesia.

Cytotoxicity of local anesthetics on rabbit adipose-derived mesenchymal stem cells during early chondrogenic differentiation

Local anesthetics (LAs) are commonly used to provide peri-operative pain control in the peripheral joints. In the field of regenerative medicine, adipose-derived mesenchymal stem cells (ADMSCs) are gaining attention as a cellular source for repair and regeneration in degenerative diseases. However, previous studies have demonstrated that the commonly used drugs lidocaine, ropivacaine, bupivacaine and mepivacaine may be toxic to human chondrocytes, which has raised concerns over whether they exert similar negative effects on ADMSCs during early chondrogenic differentiation. In the present in vitro study, the cytotoxicity of different LAs to ADMSCs was determined during early chondrogenic differentiation. At concentrations similar to those after physiological dilution once injected into the degenerative tissues, LAs (1% lidocaine, 0.5% bupivacaine, 0.5% ropivacaine or 2% mepivacaine) and PBS (control group) were incubated with rabbit ADMSCs (rADMSCs) for 60 min. Following further culture for 3 or 7 days, the cell viability, apoptosis and morphological alterations of chondrogenic differentiation were measured by determining the mitochondrial activity, by flow cytometric analysis, Safranine Fast Green double staining and reverse transcription-quantitative polymerase chain reaction of chondrogenesis-associated genes. The results indicated that the mitochondrial activity in rADMSC was decreased and the apoptotic rate was increased, following treatment with LAs (P<0.05). Lidocaine (1%) was less cytotoxic to rADMSCs during early chondrogenesis compared with other LAs. The expression levels of chondrogenesis-associated markers, including collagen I, collagen III and sex-determining region Y box 9 were all decreased at day 3 following exposure to LAs compared with the control group (P<0.05). The expression levels of these chondrogenesis-associated genes began to increase on day 7 following exposure but remained lower compared with the control group (P<0.05). Of note, 2% mepivacaine and 1% lidocaine exhibited a less pronounced negative effect on chondrogenesis-associated gene expression compared with other LAs. Therefore, the present study concluded that LAs are cytotoxic to rADMSCs during early chondrogenesis. Attention should be paid to the different types of LA selected in conjunction with ADMSC injection therapy.

Keratopathy due to ophthalmic drug abuse with corneal melting and perforation presenting as Mooren-like ulcer: A case report

The present report describes the clinical course and treatment of a Mooren-like ulcer associated with abuse of topical anesthetics and dexamethasone. A 38-year-old male physician treated himself with lidocaine, tetracaine and dexamethasone (DEX) eye drops for severe pain and decline of vision in both eyes. After six months of treatment, his right cornea exhibited annular melting with full-thickness stromal infiltration at the limbus and central corneal haze. His left cornea was completely melted and exhibited iris prolapse. The patient was treated with topical antibiotics, lubricants and underwent a binocular keratoplasty. The surgery was successful and after eight months the postoperative best-corrected visual acuities were counting fingers in the right eye and light perception in the left eye. In summary, this report documents a severe case of keratopathy presenting as Mooren-like ulcer caused by topical anesthetics and DEX, which were treated via keratoplasty, resulting in useful vision being retained.

Recovery after cataract surgery

Cataract surgery is the most common ophthalmological surgical procedure, and it is predicted that the number of surgeries will increase significantly in the future. However, little is known about the recovery after surgery. The first aim of this study was to evaluate the prevalence, severity and duration of pain and other ocular discomfort symptoms experienced after cataract surgery. The other objectives were to identify the factors associated with lower postoperative patient satisfaction and to measure the effect of cataract surgery on patients' health-related quality of life (HRQoL) and visual function in everyday life. The study design was a prospective follow-up study. The course of the recovery and the presence of ocular symptoms were evaluated by interviewing the patients via a questionnaire at 1 day, 1 week, 6 weeks and one year after surgery The visual functioning in everyday life was measured with Visual Functioning Index VF-7 and Catquest-9SF-questionnaires and furthermore the HRQoL was measured with the 15D-instrument before surgery and at 12 months after surgery. The patients returned the questionnaires by mail and were interviewed in the hospital on the day of the surgery. The same patients filled-in all the questionnaires. The patient reports were used to collect the data on medical history. A total of 303 patients were approached at Kuopio University Hospital in 2010-2011 and of these 196 patients were eligible and willing to participate, with postoperative data being available from 186 (95%) patients. A systematic review article was included in the study procedure and it revealed the wide range in the reported incidence of postoperative ocular pain. Some of the identified randomized controlled studies reported no or only minor pain whereas in some studies significant pain or pain lasting for several weeks has been described in more than 50% of the study patients. In the present study setting, pain was reported by 34% during the first postoperative hours and by approximately 10% of patients during the first six weeks after surgery. During the early recovery in the hospital, only a minority of the patients reporting pain were provided with pain medication. The ocular discomfort symptoms such as itchiness, burning, foreign-body sensation and tearing were common both before (54%) and after surgery (38-52%). These symptoms can also be described as painful symptoms and are often difficult to distinguish from ocular pain. The symptoms are also typical of ocular surface disease, and some patients may benefit from the postoperative administration of tear substitutes. The patients reporting postoperative ocular symptoms were less satisfied with the treatment outcome at 12 months after surgery (p = 0.001) compared to the patients who experienced no symptoms. Those patients reporting less disability in visual functioning before surgery were more satisfied than patients with more reported disability. The HRQoL improved significantly after cataract surgery (p = 0.002). However, when compared to an age-and gender-standardized control population, in cataract subjects the HRQoL remained slightly worse both before and at 12 months after surgery.

Cytotoxicity of lidocaine to human corneal endothelial cells in vitro

Lidocaine has been reported to induce apoptosis on rabbit corneal endothelial cells. However, the apoptotic effect and exact mechanism involved in cytotoxicity of lidocaine are not well-established in human corneal endothelial (HCE) cells. In this study, we investigated the apoptosis-inducing effect of lidocaine on HCE cells in vitro. After HCE cells were treated with lidocaine at concentrations of 0.15625-10.0 g/l, the morphology and ultrastructure of the cells were observed by inverted light microscope and transmission electron microscope (TEM). Cell viability was measured by MTT assay, and the apoptotic ratio was evaluated with flow cytometry and fluorescent microscopic counting after FITC-Annexin V/PI and AO/EB staining. DNA fragmentation was detected by electrophoresis, and the activation of caspases was evaluated by ELISA. In addition, changes in mitochondrial membrane potential were determined by JC-1 staining. Results suggest that lidocaine above 1.25 g/l reduced cellular viability and triggered apoptosis in HCE cells in a time- and dose-dependent manner. Diminishment of ΔΨm and the activation of caspases indicate that lidocaine-induced apoptosis was caspase dependent and may be related to mitochondrial pathway.

Local anesthetic lidocaine induces apoptosis in human corneal stromal cells in vitro

AIM

To demonstrate the apoptosis-inducing effect of lidocaine on human corneal stromal (HCS) cells in vitro, and provide experimental basis for safety anesthetic usage in clinic of ophthalmology.

METHODS

In vitro cultured HCS cells were treated with lidocaine at different doses and times, and their morphology was monitored successively with inverted phase contrast microscopy. The membrane permeability of them was detected by acridine orange/ethidium bromide (AO/EB) double staining. The DNA fragmentation of them was examined by agarose gel electrophoresis, and their ultrastructure was observed by transmission electron microscopy (TEM), respectively.

RESULTS

Exposure to lidocaine at doses from 0.3125g/L to 20g/L induced morphological changes of HCS cells such as cytoplasmic vacuolation, cellular shrinkage, and turning round, and elevated membrane permeability of these cells in AO/EB staining. The change of morphology and membrane permeability was dose- and time-dependent, while lidocaine at dose below 0.15625g/L could not induce these changes. Furthermore, lidocaine induced DNA fragmentation and ultrastructural changes such as cytoplasmic vacuolation, structural disorganization, chromatin condensation, and apoptotic body appearance of the cells.

CONCLUSION

Lidocaine has significant cytotoxicity on human corneal stromal cells in vitro in a dose- and time-dependent manner by inducing apoptosis of these cells. The established experimental model and findings based on this model here help provide new insight into the apoptosis-inducing effect of local anesthetics in eye clinic.

Postoperative pain after cataract surgery

Cataract extraction surgery is the most common surgical procedure, but knowledge of postoperative pain related to cataract surgery is sparse. In this systematic review, the incidence, prevalence, and management of pain after phacoemulsification surgery were identified using PubMed and Scopus. Selected studies were restricted to randomized controlled trials with interventions on postoperative inflammation and pain. Data from 105 articles were extracted and 21 studies met the final inclusion criteria. Most studies reported no or only mild postoperative pain, but some reported moderate and severe pain and pain lasting several weeks. The interventions consisted of drug therapy including topical nonsteroidal antiinflammatory drugs, corticosteroids, paracetamol, perioperative intraocular injections, eye pads used after surgery, and various surgical techniques. The reviewed literature indicates that cataract surgery is associated with significant postoperative pain in some patients, who should be provided with appropriate counseling and pain treatment.

Use of topical anesthetic and non-medical alternatives in welding workers regarding ophthalmic problems

PURPOSE

Welding workers' ophthalmic problems resulting from their professions are frequently observed in ophthalmic emergencies and can cause severe visual impairment. We aimed to investigate the use of topical anesthetic and non-medical alternatives of this population regarding ophthalmic problems in this study.

MATERIALS AND METHODS

The study included 204 welding workers randomly selected from a population of 1852 people who had at least one-year experience as a welding worker and who were members of a chamber of welding workers. Data were collected at face to face interviews with a questionnaire composed of questions about ophthalmic problems caused by their profession and about how they eliminated these problems. Obtained data were analyzed with SPSS.

RESULTS

Of 204 workers, 38.7% preferred non-medical alternatives including application of potatoes (22%), dressing with tea (17%), rinsing with cold water (3.4%) and closing eyes (2%). 30.5% of the participants used topical anesthetics (72% commercial and 28% prepared in pharmacies). There was a significant relation between use of non-medical methods and topical anesthetics, and workers' education, duration of work experience and receiving training from their seniors (p < 0.05).

CONCLUSION

Use of non-medical methods and topical anesthetics by welding workers was found to be associated with low-education levels and insufficient knowledge about ophthalmologic problems due their professions and their treatment. They should be provided with appropriate training for the issue and precautions should be taken to prevent people from buying drugs without a prescription.

Coenzyme Q10 does not enhance preadipocyte viability in an in vitro lipotransfer model

BACKGROUND

Autologous fat is an attractive soft-tissue filler in plastic and reconstructive surgery. The success of the procedure relies strongly on the technique of transferring viable preadipocytes. Among other factors, preadipocyte viability is impaired by local anesthetics. Application of coenzyme Q10 is being performed by aesthetic plastic surgeons to enhance the success of lipotransfer. The aim of this study was to evaluate the effect of Q10 on preadipocyte viability with special regard to impairment after lidocaine treatment.

METHODS

Preadipocytes were pretreated with coenzyme Q10 or vehicle control followed by incubation with lidocaine for 30 min. Viability and apoptosis were assessed by FACS analysis and Western blot.

RESULTS

Coenzyme Q10 did not improve viability nor have any effect on investigated apoptosis parameters. Preadipocyte viability was reduced after lidocaine treatment. Surface binding of annexin V, cleavage of caspase-3, and abundance of subdiploid cells were not detectable though, suggesting that necrosis rather than apoptosis is the cause for reduced preadipocyte viability.

CONCLUSION

Our results indicate that Q10 does not improve preadipocyte viability. Preadipocyte cell death induced by lidocaine is not caused by apoptosis but by necrosis, which cannot be prevented by coenzyme Q10. These findings should be taken into account when searching for solutions to improve preadipocyte viability in the context of soft tissue engineering and autologous fat transfer.

Dilute proparacaine for the management of acute corneal injuries in the emergency department

OBJECTIVE

Dogma discourages the provision of topical anesthetics to patients with corneal injuries discharged from the emergency department because of the toxicity of concentrated solutions. We compared the analgesic efficacy of dilute topical proparacaine with placebo in emergency department patients with acute corneal injuries.

METHODS

We conducted a prospective randomized controlled trial of adults with corneal injuries presenting to one of 2 tertiary care emergency departments in London, Ont. Patients were randomly assigned to groups receiving either 0.05% proparacaine or placebo drops as outpatients and were followed up to healing by a single ophthalmologist. Our primary outcome was pain reduction as measured on a 10-cm visual analog scale.

RESULTS

Fifteen participants from the proparacaine group and 18 participants from the placebo group completed the study. The mean age of the patients was 38.7 (standard deviation 12.3) years and the majority were male (85%). Pain reduction was significantly better in the proparacaine group than in the placebo group, with a median improvement of 3.9 (interquartile range [IQR] 1.5-5.1) cm on the visual analog scale versus a median improvement of 0.6 (IQR 0.2-2.0) cm (p = 0.007). The proparacaine group was more satisfied (median level of satisfaction 8.0 [IQR 6.0-9.0] cm on a 10-cm visual analog scale v. 2.6 [IQR 1.0-8.0] cm, p = 0.027). There were no ocular complications or signs of delayed wound healing in either group.

CONCLUSION

Dilute topical proparacaine is an efficacious analgesic for acute corneal injuries. Although no adverse events were observed in our study population, larger studies are required to evaluate safety.

Local anesthetics have a major impact on viability of preadipocytes and their differentiation into adipocytes

BACKGROUND

Autologous fat transplantation is a well-established technique in surgery. Moreover, the use of preadipocytes in soft-tissue engineering is currently being intensely investigated. Current efforts focus on identifying maneuvers that may minimize resorption and provide predictable late results. The aim of this study was to investigate the influence of different local anesthetics frequently used in clinical practice on the viability of preadipocytes and their ability to differentiate into adipocytes.

METHODS

Human preadipocytes were isolated from subcutaneous adipose tissue of 15 patients and treated with bupivacaine, mepivacaine, ropivacaine, articaine/epinephrine, and lidocaine for 30 minutes. Viability was determined directly after treatment and during the ensuing cultivation. Differentiation of preadipocytes was determined by expression of the adipocyte marker adiponectin.

RESULTS

Although the immediate effects of mepivacaine and ropivacaine were only moderate, treatment with articaine/epinephrine and lidocaine strongly impaired preadipocyte viability. Cells normally attached to the culture dishes and proliferated irrespective of the previous treatment. During long-term cultivation, articaine/epinephrine-treated cell viability decreased markedly, whereas other local anesthetics had no impact. Despite normal phenotypic appearance of cells treated with bupivacaine, mepivacaine, ropivacaine, and lidocaine, all local anesthetics markedly impaired adipocyte differentiation as determined by adiponectin expression.

CONCLUSIONS

The authors' results show that there is a marked influence of local anesthetics not only on the quantity but also on the quality of viable preadipocytes as determined by their ability to differentiate into mature adipocytes. Therefore, these results should be considered in the context of autologous fat transfer and soft-tissue engineering.

Induction of apoptosis of rabbit corneal endothelial cells by preservative-free lidocaine hydrochloride 2%, ropivacaine 1%, or levobupivacaine 0.75%

PURPOSE

To determine and compare the amount of apoptosis and changes in rabbit corneal endothelial cell morphology after intracameral administration of different anesthetic agents.

SETTING

Department of Ophthalmology, Baskent University Medical Faculty, Ankara, Turkey.

METHODS

Right eyes of 64 Vienna white rabbits were injected intracamerally with preservative-free lidocaine hydrochloride 2%, ropivacaine 1%, levobupivacaine 0.75%, or fortified balanced salt solution (BSS Plus) (control). Animals were humanely killed 1 day or 7 days later. Terminal deoxynucleotidyl transferase deoxy-UTP-nick end labeling was used to detect apoptosis. Corneal endothelial cells and apoptotic cells were counted by light microscopy. The morphologic appearance was determined by transmission electron microscopy (TEM).

RESULTS

Apoptotic cell density was high in the anesthetic groups on day 1 (P<.01); there was no significant difference between groups at 7 days. Apoptotic cell density declined significantly between 1 day and 7 days in the anesthetic groups (P<.05) but not in the control group. There was no difference in endothelial cell density between the 4 groups at 1 or 7 days. All anesthetic groups showed degenerative changes on TEM, with the least change in the preservative-free lidocaine hydrochloride 2% group.

CONCLUSIONS

Intracameral injections of preservative-free lidocaine, ropivacaine, and levobupivacaine induced significantly more apoptotic endothelial cell loss than BSS Plus and led to morphologic changes in the corneal endothelial cells in the early period. This effect was temporary, with recovery by 7 days. Considering the limited proliferative capacity in human eyes, the induced apoptosis might result in the permanent cell loss and enlargement in human corneal endothelium.

Viability of preadipocytes in vitro: the influence of local anesthetics and pH

BACKGROUND

Autogenous fat transfer with lipoinjection for soft tissue augmentation is a commonly used surgical technique. Abundant donor tissue availability and relative ease of harvesting have made autologous fat an attractive soft tissue filler. The overall reliability of this technique is often disputed, and different authors describe different results after autologous fat transplantation despite using similar techniques. In this study, we examined the influence of different local anesthetics commonly used in fat harvest and the pH of the anesthetic solution on the viability of harvested preadipocytes.

METHODS AND MATERIALS

Preadipocytes were incubated with 1% lidocaine, 1% articaine plus epinephrine 1:200,000, 0.75% ropivacaine, and 1% prilocaine or our standardized tumescent solution (1 L of 0.9% sodium chloride solution plus 25 mL of 1% articaine plus epinephrine 1:200,000 plus 25 mL of bicarbonate) for 30 minutes. Additionally, we incubated cells with the local anesthetics as described above but diluted 1:2 with phosphate buffered saline (pH 7.4). Viability was measured using trypan blue dying as well as propidium iodine staining and fluorescence-activated cell sorting analysis.

RESULTS

There are significant differences in the viability of preadipocytes under the influence of various local anesthetics.

DISCUSSION

Our data could partially explain the varying results after autogenous fat transfer.

In vitro benzyl alcohol cytotoxicity: implications for intravitreal use of triamcinolone acetonide

The aim of the study was to investigate the toxicity of benzyl alcohol (BA), the preservative in commercial triamcinolone acetonide (TA) suspensions, on retinal pigment epithelial (RPE) cells. Cultured RPE cells from a human cell line (ARPE-19) and from rabbits were exposed to the balanced salt solution (control) or BA (0.0225, 0.225, 0.9, 3 or 9mg/mL) for 5, 30, 60, or 120min. Morphological changes of RPE cells were evaluated by the trypan blue in situ staining. The proportions of dead cells were quantitatively measured by the trypan blue exclusion assay, and those of functional cells were assessed by a mitochondrial dehydrogenase assay. The mechanism of cytotoxicity was determined by the acridine orange/ethidium bromide staining and DNA laddering technique. Furthermore, ultrastructural changes were observed by transmission electron microscopy. The results showed that RPE cell damage was dose- and time-dependent. BA 0.225mg/mL, the clinically relevant concentration in TA following intravitreal injection, caused ultrastructural damage and impaired human RPE cell function at 2h; but BA 0.0225mg/mL did not. BA 9.0mg/mL, the concentration in commercial TA suspensions, was toxic within 5min on each assay for both human and rabbit RPE cells. The major mechanism of cell death was necrosis. In conclusion, BA in commercial TA suspensions injected intravitreally (0.225-9mg/mL) can damage RPE cells. Our in vitro study on benzyl alcohol cytotoxicity has significant clinical implications for intravitreal use of TA. We suggest that, before a commercial TA solution is used intravitreally, the vehicle should be removed to prevent damaging the RPE layer, particularly during macular hole surgery. Commercial development of a preservative-free TA suspension for intraocular use is urged.

Severe endothelial cell loss following uneventful angle-supported phakic intraocular lens implantation for high myopia

Endothelial decompensation is a serious complication of phakic intraocular lens (pIOL) implantation and is a major concern during the postoperative period. We report 3 eyes in which the same foldable angle-supported pIOL was implanted to correct high myopia. Rapid and severe postoperative endothelial cell loss occurred in all 3 eyes. An over-sized pIOL that induced excessive vaulting into the anterior chamber was the main risk factor. In 2 eyes, the pIOL was explanted uneventfully; 1 eye required Descemet's stripping automated endothelial keratoplasty because of total endothelial decompensation. These cases illustrate the importance of accurate sizing of foldable angle-supported anterior chamber pIOLs to avoid excessive vaulting. They also highlight the importance of regular follow-up and preventive pIOL explantation as soon as significant endothelial cell loss is detected.

Safety and efficacy of two ocular anesthetic methods for phacoemulsification: topical anesthesia and viscoanesthesia (VisThesia)

PURPOSE

VisThesia is a new ophthalmic viscosurgical device (OVD) which has 1% lidocaine combined with 1.5% sodium hyaluronate. This is a prospective evaluation of the safety and efficacy of VisThesia used in association with phacoemulsification.

METHODS

A total of 114 eyes were divided into two groups. Fifty-nine eyes were treated with tetracaine + oxybuprocaine topical anesthesia and DuoVisc OVD and 55 eyes were treated with VisThesia, for use as both topical anesthetic and OVD. Endothelial cell counts were measured at 30 days postoperatively and compared to preoperative baseline values. Pain and discomfort was subjectively evaluated by patients using a visual analog pain scale (0-10).

RESULTS

All surgeries were uneventful with no intraoperative or immediate postoperative complications. Patients receiving topical anesthesia had a mean pain score of 1.1+/-6.8 compared to a mean score of 1.3+/-4.6 for patients receiving VisThesia (p=0.59). Postoperatively, endothelial cell loss at 1 month was greater for patients receiving VisThesia (20.32%+/-43.75) than for those receiving the topical anesthetic (8.8%+/-59.6; p<0.0001).

CONCLUSIONS

The results from the visual analog pain scale were comparable between groups, showing that VisThesia provides similar pain relief to topical anesthesia. Specular microscopy performed at 30 days postoperatively showed a significantly greater loss of endothelial cells with the use of VisThesia, suggesting that the 1% lidocaine concentration used in VisThesia may be toxic to corneal endothelial cells.

Lidocaine effects on corneal endothelial cell ultrastructure

The purpose of this study was to determine whether intracameral commercial lidocaine 2% induces alterations on the rabbit corneal endothelium. Forty white rabbits received different substances inside the anterior chamber: group (G)1, no substance; G2 and G3 received lidocaine 2% with preservative in aqueous solution; G4 and G5, lidocaine 2% with preservative in gel solution; G6 and G7, the anesthetic preservative (metilparahydroxybenzoate 0.1%); and G8 and G9, lidocaine 2% without preservative in aqueous solution. The animals from G2, 4, 6 and 8 were sacrificed after 1 h, and from G3, 5, 7 and 9 after 24 h after injection of the substance inside the anterior chamber. The corneas were clinically evaluated and assessed by transmission and scanning electron microscopy. G1, 2, 6, 7, 8 and 9 animals had very similar characteristics in clinical, ultrastructural and morphometric evaluations; the G3 and G4 animals showed discrete edema and one animal in G5 had intense corneal edema. We conclude that lidocaine 2% with preservative induces few ultrastructural alterations in the corneal endothelial cells.

Triamcinolone acetonide suspension toxicity to corneal endothelial cells

PURPOSE

To investigate the cytotoxicity of triamcinolone acetonide (TA) suspensions to corneal endothelial cells (CECs).

SETTING

Department of Ophthalmology, Institute of Clinical Medicine, College of Medicine, National Cheng Kung University, Tainan, Taiwan.

METHODS

New Zealand white rabbit CECs were exposed for 1 minute to balanced salt solution (BSS); commercial TA suspension (cTA); vehicle-removed TA (-vTA); pure vehicle (V); 1/10 dilutions of cTA, -vTA, or V in BSS; or benzyl alcohol (BA) (cTA preservative) 9 mg/mL. Corneal endothelial cell toxicity was assessed by light microscopy (trypan blue staining) and transmission electron microscopy. The effects of 3-, 10-, or 30-minute exposures to 1/10 cTA, 1/10 -vTA, or V were also investigated.

RESULTS

One-minute exposures to -vTA or 1/10 -vTA did not damage CECs; however, cTA, V, or 1/10 dilutions of cTA or V caused damage and cells exposed to BA showed severe ultrastructural damage/lysis. A 30-minute exposure to 1/10 -vTA did not cause significant cell damage, whereas 3- to 30-minute exposures to 1/10 cTA or V showed significant time-dependent cytotoxicity.

CONCLUSIONS

Commercial TA suspension was cytotoxic to cultured rabbit CECs because of the preservative, BA, in the vehicle. Because 1/10 -vTA appeared to be safe for up to 30 minutes of exposure, use of 1/10 dilutions of vehicle-removed TA is suggested to help surgeons visualize prolapsed vitreous during anterior vitrectomy in complicated cataract surgeries.