The effects of bupivacaine and lidocaine on the corneal endothelium when applied into the anterior chamber at the concentrations supplied commercially

Intracameral Drug Delivery: A Review of Agents, Indications, and Outcomes

An intracameral (IC) injection directly delivers the drug into the anterior chamber of the eye. This targeted drug delivery technique overcomes the ocular barriers and offers a high therapeutic concentration of medication at the desired site and consequently better clinical outcomes. IC drug delivery is a safe and effective modality with many advantages over topical delivery. These include excellent bioavailability, reduced systemic risk, and minimal ocular toxicity. Agents delivered via IC injection have shown promising results against infection, inflammation, ocular hypertension, and neovascularization. Current literature shows that IC antibiotics, including cefuroxime, vancomycin, and moxifloxacin, are routinely used for prophylaxis of endophthalmitis. Other drugs available for IC use are steroids, anesthetics, mydriatics, miotics, antivascular endothelial growth factor, antiglaucoma, and alkylating agents. Introduction of sustained-release devices containing dexamethasone or Bimatoprost in anterior chamber via IC route has the potential in treating ocular inflammation and raised intraocular pressure. The complications such as hemorrhagic occlusive retinal vasculitis and toxic anterior segment syndrome have been documented with IC prophylaxis but are rare. In this review, we provide an overview of available IC drugs, their pharmacokinetics, the spectrum of activity, dosage and preparation, prophylactic and therapeutic usage, clinical efficacy, and safety profiles.

Toxic anterior segment syndrome: A review

Toxic anterior segment syndrome is a surgical complication characterized by a noninfectious anterior chamber inflammatory reaction having multiple etiologies. The clinical signs (prominent limbus-to-limbus corneal edema, anterior chamber inflammation) and symptoms (decreased visual acuity, discomfort) generally occur within the first 12-48 hours after intraocular surgery. Most patients achieve good clinical and visual outcomes when there is a prompt clinical diagnosis and adequate treatment. We review the literature on toxic anterior segment syndrome, emphasizing its etiology, pathophysiology, and clinical and surgical management, as well as prognosis and sequelae. Our goal is to reduce the frequency of toxic anterior segment syndrome by highlighting the importance of prevention, early recognition, and distinguishing toxic anterior segment syndrome from infectious endophthalmitis.

Comparison between ropivacaine and bupivacaine in deep topical fornix nerve block anesthesia in patients undergoing cataract surgery by phacoemulsification

Purpose

In this study, we intend to analyze ropivacaine and bupivacaine in various parameters during phacoemulsification under deep topical fornix nerve block (DTFNB), a known form of nerve block for phacoemulsification.

Methods

This prospective randomized study was conducted on 100 patients undergoing elective cataract surgery by phacoemulsification under DTFNB. Patients were divided into two equal groups of fifty patients each, Groups B (bupivacaine) and Group R (ropivacaine). Two sponges, approximately 2 mm × 3 mm dimensions, saturated with either 0.5% bupivacaine or 0.75% ropivacaine were placed deep in the conjunctival fornices to perform the deep topical block. Both groups were evaluated for magnitude of pain and discomfort at various stages of phacoemulsification using a simple pain scoring system. The level of surgeon satisfaction, requirement for supplementary anesthesia, and surgical complications were also evaluated. Quantitative variables between the two groups were compared using unpaired t-test. Qualitative variables were correlated using Chi-square test.

Results

Overall demographic parameters of patients were similar in both groups. Similar mean pain scores were found in the ropivacaine and bupivacaine groups, with no statistical significance. Surgical satisfaction and the need for supplemental anesthesia were also statistically insignificant.

Conclusion

Ropivacaine is a good alternative for deep topical anesthesia as it has a better safety margin and lesser toxic effect than other comparable local anesthetic agents.

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.

Toxic Anterior Segment Syndrome after Uncomplicated Cataract Surgery

Purpose

To evaluate the anterior segment examination findings and the response to medical therapy of patients who had toxic anterior segment syndrome (TASS) after uncomplicated cataract surgery.

Methods

Fourteen eyes of 14 patients were enrolled in the study. Visual acuity, biomicroscopic anterior segment examination, intraocular pressure measurement, and fundus examination were performed to assess TASS occurring during postoperative 12–48 hours after uncomplicated phaco surgery. The visual impairment, corneal edema, tyndallization, fibrin formation, hypopyon, vitritis, and response to steroid therapy were evaluated prospectively.

Results

After topical steroid therapy lasting for 1 week, visual acuity improved in 11 eyes. No significant visual improvement occurred in 3 eyes. Significant corneal edema was found in 4 and mild corneal edema was observed in the other 10 eyes. Fibrin reaction occurred in 5 and tyndallization in various degrees was positive in all eyes. There was a 1-mm hypopyon in 1 patient. There was no sign of vitritis and steroid therapy was effective in all of the patients. In addition to topical treatment with steroid and antibiotic drops; systemic and subconjunctival steroids were used in 3 patients who had fibrin formation and in one patient who had hypopyon.

Conclusions

After uncomplicated cataract surgery, toxic anterior segment may occur in the early postoperative period, which is treated successfully with steroids. More studies are needed to understand the multifactorial risk factors affecting the etiopathogenesis of this syndrome.

Evaluation of Intracameral Pentablock Copolymer Thermosensitive Gel for Sustained Drug Delivery to the Anterior Chamber of the Eye

PURPOSE

To investigate PTSgels (Pentablock copolymers) as an injectable formulation technology for sustained ocular drug delivery. Drug release profile, tolerability, and polymer degradation for one of the thermosensitive, biodegradable, and biocompatible compositions were investigated through intracameral (IC) injection in rabbits.

METHODS

New Zealand White rabbit eyes were injected IC (50 μL) with 100 μg near-infrared-immunoglobulin G (NIR-IgG) in balanced salt solution (BSS) or 20% PTSgel; or with PTSgel or BSS alone. Ocular irritation scoring, intraocular pressure (IOP), and corneal thickness (CT) measurement, as well as color and infrared photography, were performed for up to 28 days postinjection. Upon euthanasia at 7, 14, or 28 days, eyes underwent ex vivo imaging (Xenogen IVIS) followed by tissue fixation and histopathology.

RESULTS

IC injection of PTSgel (liquid at room temperature) was performed without difficulty using a 31G needle. The polymer quickly gelled in the IC space resulting in an inferior anterior chamber deposit. The tested PTSgel was well tolerated, with no significant changes in IOP or CT. Eyes injected with NIR-IgG in PTSgel had visible NIR-IgG through 9 days postinjection, and ex vivo imaging detected a strong NIR-IgG signal in the anterior chamber through day 28. The gel deposit steadily decreased in size over time and was nearly eliminated by 28 days.

CONCLUSIONS

The PTSgel released IgG for 28 days and was well tolerated. The polymer degraded in parallel with drug release. These results demonstrate the potential of intracameral PTSgel formulations for sustained delivery of biologic therapies to the ocular anterior segment.

Outbreak of late-onset toxic anterior segment syndrome after implantation of one-piece intraocular lenses

PURPOSE

To describe clinical findings associated with an outbreak of toxic anterior segment syndrome (TASS) after implantation of 1-piece intraocular lenses (IOLs; HOYA iSert(®) 251 and 255; HOYA Co Ltd, Tokyo, Japan) contaminated with aluminum.

DESIGN

Multicenter observational retrospective case series.

METHODS

Cases developing TASS after IOL implantation from November 2011 to February 2013 were reported to the HOYA IOL-Related Endophthalmitis Investigation Committee. Infectious endophthalmitis was excluded. Data were collected on patient backgrounds, the time from IOL implantation to development of the first symptoms, clinical findings, treatment, and best-corrected visual acuity (BCVA) scores before and after treatment. BCVA data were converted into logMAR figures to allow for statistical analysis.

RESULTS

We identified 251 cases of late-onset TASS in patients of mean age 72.85 years treated in 183 hospitals. Common clinical features included the presence of anterior chamber cells (99.2%), conjunctival injection (41.4%), fibrinous inflammation (26.7%), and hypopyon (22.7%). Mean BCVA at the onset of ocular inflammation was 0.253 ± 0.424. The mean time from IOL implantation to development of the first symptoms was 38.44 ± 32.29 days. Of all eyes, 142 were treated with steroids and antibiotics, and 109 underwent surgery, including washing of the anterior chamber, removal of the IOL, and vitrectomy. Mean BCVA after treatment was 0.036 ± 0.242, significantly better than at the onset of ocular inflammation (P < .05).

CONCLUSION

This is the first report of an outbreak of late-onset TASS after implantation of a particular type of IOL.

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.

[Toxic anterior segment syndrome]

Toxic anterior segment syndrome (TASS) is a general term used to describe acute, sterile postoperative inflammation due to a non-infectious substance that accidentally enters the anterior segment at the time of surgery and mimics infectious endophthalmitis. TASS most commonly occurs acutely following anterior segment surgery, typically 12-72h after cataract extraction. Anterior segment inflammation is usually quite severe with hypopyon. Endothelial cell damage is common, resulting in diffuse corneal edema. No bacterium is isolated from ocular samples. The causes of TASS are numerous and difficult to isolate. Any device or substance used during the surgery or in the immediate postoperative period may be implicated. The major known causes include: preservatives in ophthalmic solutions, denatured ophthalmic viscosurgical devices, bacterial endotoxin, and intraocular lens-induced inflammation. Clinical features of infectious and non-infectious inflammation are initially indistinguishable and TASS is usually diagnosed and treated as acute endophthalmitis. It usually improves with local steroid treatment but may result in chronic elevation of intraocular pressure or irreversible corneal edema due to permanent damage of trabecular meshwork or endothelial cells.

Ocular rupture after accidental intraocular injection of bupivacaine

PURPOSE

To report on the toxicity of bupivacaine that was accidentally injected into the eye.

METHODS

Observational case report. Clinical and electroretinographic examinations of a 78-year-old woman who had an ocular rupture after an accidental intraocular injection of 0.25% bupivacaine.

RESULTS

The a- and b-waves of the electroretinographics were normal after the repair of the eye by vitrectomy. The corneal opacification and edema present after the rupture did not recover.

CONCLUSION

The exposure of the retina to 0.25% bupivacaine may not alter the function of the human retina.

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.

Cataract surgery anaesthesia: is topical anaesthesia really better than retrobulbar?

PURPOSE

To compare the effectiveness for the patient of retrobulbar anaesthesia (RBA) and topical anaesthesia (TA) in cataract surgery by phacoemulsification.

METHODS

We performed a prospective, randomized study on 115 patients operated at our clinic using the two anaesthesia techniques. The RBA group comprised 57 patients (20 women, 37 men; age 72 +/- 10 years); the TA group comprised 58 patients (20 women, 38 men; age 74 +/- 10 years). Measured parameters were: blood pressure; heart rate; blood oxygen saturation level; serum adrenaline, noradrenaline and cortisol levels; white blood cell count; indicated pain during the procedure, and pain as reported by the patient afterwards. Two psychological tests were used: the State-Trait Anxiety Inventory (STAI), and the patient-selected face-scale test. Statistical analysis was performed using Student's t-test and the chi-square test. Results were also analysed using a logistic regression model.

RESULTS

Both types of anaesthesia were adequate for the surgical procedure. In the RBA group fewer patients experienced pain during surgery (p < 0.01) and fewer recalled any perioperative discomfort. With RBA the objective parameters were more stable than with TA, and systolic blood pressure was significantly lower (p = 0.01). The logistic model was able to predict perioperative pain with 93% certainty. Pain sensitivity was higher in younger patients and in patients with higher initial cortisol and noradrenaline serum levels.

CONCLUSIONS

Both methods of anaesthesia are appropriate, but phacoemulsification with TA is more painful than with RBA. In hypertonic patients and younger patients who are more susceptible to pain, TA should be avoided or used in combination with individualized sedation.

Inadvertent ocular perforation during lid anesthesia for hordeolum removal

PURPOSE

Ocular perforation during lid anesthesia is rarely reported. We describe here a case of inadvertent corneal perforation and traumatic cataract that occurred during lid anesthesia in a procedure for hordeolum removal.

METHODS

A 33-year-old woman presented with a sudden visual loss of her left eye. She had undergone hordeolum removal the day before at a local clinic. On ophthalmologic examination, the cornea was perforated and the lens cortex was extruded into the anterior chamber. After cataract removal and IOL implantation, antibiotics were injected into the vitreous.

RESULTS

Her final visual acuity of the left eye was 20/20. Postoperative specular microscopic examination revealed a normal-range endothelial cell count, coefficient of variation, and hexagonality despite the intracameral lidocaine injection.

CONCLUSIONS

Anesthetic injection of an infected lid should be done with great caution. Although there are possibilities of corneal endothelial toxicity and endophthalmitis in case of intracameral lidocaine injection through the infected lid, yet proper management may save the patient's vision without complications.

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

PURPOSE

To investigate the corneal endothelial cytotoxicity of commercial formulations of agents used for intracameral anesthesia in cataract and other ocular surgery.

METHODS

Cultured corneal endothelial cells (CECs) of New Zealand White rabbits were exposed for 1 minute to balanced salt solution (control); Xylocaine (lidocaine) 1% E (with epinephrine), 2% E, 2%, or 4%; or Marcaine (bupivacaine) 0.5% or 0.5% spinal heavy. The degree of cytotoxicity was determined by in vitro staining with trypan blue and light microscopic evaluation of cell morphology. The effect of longer exposure (up to 16 minutes) to lidocaine 1% E was also investigated.

RESULTS

CECs were not significantly damaged by 1-minute exposure to lidocaine 1% E or 2% E; however, significant cytotoxicity was seen after 1-minute exposure to lidocaine 2% or 4% or bupivacaine 0.5% or 0.5% spinal heavy. Exposure to lidocaine 1% E showed a trend toward time-dependent cytotoxicity that reached significance at 16 minutes.

CONCLUSIONS

One-minute exposure to lidocaine 1% E or 2% E appears to be safe for cultured rabbit CECs, although longer exposures could cause time-dependent cytotoxicity, which should be considered in planning cataract or other ocular surgery. Because bupivacaine 0.5% and 0.5% spinal heavy cause cytotoxic effects within the first minute of contact with CECs, they should be used with great caution, if at all, in the anterior chamber of human eyes.

Toxic anterior segment syndrome

Toxic anterior segment syndrome (TASS) is a sterile postoperative inflammatory reaction caused by a noninfectious substance that enters the anterior segment, resulting in toxic damage to intraocular tissues. The process typically starts 12 to 48 hours after cataract/anterior segment surgery, is limited to the anterior segment of the eye, is always Gram stain and culture negative, and usually improves with steroid treatment. The primary differential diagnosis is infectious endophthalmitis. Review of the literature indicates that possible causes of TASS include intraocular solutions with inappropriate chemical composition, concentration, pH, or osmolality; preservatives; denatured ophthalmic viscosurgical devices; enzymatic detergents; bacterial endotoxin; oxidized metal deposits and residues; and factors related to intraocular lenses such as residues from polishing or sterilizing compounds. An outbreak of TASS is an environmental and toxic control issue that requires complete analysis of all medications and fluids used during surgery, as well as complete review of operating room and sterilization protocols.

Ocular surgical pharmacology: corneal endothelial safety and toxicity

The purpose of this review is to discuss the recently published literature related to corneal endothelial toxicity and safety. We discuss postoperative complications, such as toxic endothelial cell destruction syndrome and toxic anterior segment syndrome, that cause significant injury to the patient and anxiety to the physician. Additionally, we review recent papers related to intraocular medications, preservatives, and devices, including antibiotics, anesthetics, viscoelastics, and enzymatic sterilization detergents, that have potentially toxic effects on the corneal endothelium.