Preservative alteration of corneal permeability in humans and rabbits

Isotonic, neutral buffered solutions of benzalkonium chloride or chlorhexidine digluconate were applied topically to one eye of rabbits or human subjects. Contralateral control eyes received phosphate buffered saline as placebo. One-half hour later, the tear film of both eyes was loaded with nonpreserved sodium fluorescein. Anterior chamber fluorescence levels were measured at 1 hr intervals to determine corneal permeability changes attributable to preservative action. In rabbits, corneal permeability increased with rising preservative concentration. Benzalkonium chloride 0.01% increased anterior chamber fluorescence level 1.8 (+/- 0.2 SEM) times over control eyes, while chlorhexidine digluconate 0.01% caused 1.5 (+/- 0.2 SEM) to one ratio of fluorescence in treated/untreated eyes. In human subjects, neither preservative produced significant permeability change at 0.01% concentration. However, benzalkonium chloride 0.02% caused 1.23 (+/- 0.08 SEM) permeability increase. The results support the hypothesis that rabbits are more sensitive to single-dose applications of preservatives than humans.     

Viscoanesthesia. Part I: toxicity to corneal endothelial cells in a rabbit model

PURPOSE: To evaluate the toxicity of a solution combining sodium hyaluronate 1.5% with lidocaine (0.5%, 1.0%, or 1.65%) to the rabbit corneal endothelium. SETTING: Center for Research on Ocular Therapeutics and Biodevices, Storm Eye Institute, Medical University of South Carolina, Charleston, South Carolina, USA. METHODS: Each rabbit cornea was excised, and the endothelium was exposed to 1 of the following solutions for 20 minutes: viscoanesthetic solution (0.5%, 1.0%, or 1.65% lidocaine in sodium hyaluronate 1.5%; 5 corneas each), sodium hyaluronate 1.5% (n = 5), balanced salt solution (BSS(R)) (n = 5), mitomycin-C 0.02% (n = 2), dextran 15% (n = 2), or distilled water (n = 2). The endothelium was then stained with trypan blue and alizarin red. Two corneas were stained immediately after excision. Cell morphology and damage to the corneal endothelium were analyzed by microscopic examination. RESULTS: The endothelium in the corneas of the viscoanesthetic groups was comparable to that in the sodium hyaluronate 1.5% and the BSS groups and to the corneas not exposed to any solution. In some areas of the 1.0% and the 1.65% viscoanesthesia groups, the corneal endothelial cells presented irregular intercellular borders. Staining with trypan blue, which indicates cellular damage, was observed in some linear areas corresponding to corneal folds in all groups. The folds were probably caused during manipulation for corneal excision and staining. The corneal endothelium was destroyed in the mitomycin group. In the dextran and distilled-water groups, morphological alterations probably resulting from osmotic changes were observed. CONCLUSIONS: The 3 concentrations of viscoanesthetic solutions appeared to be safe to rabbit corneal endothelium.     

不同粘弹剂在复杂性白内障超声乳化术中的临床观察

目的:比较两种粘弹性物质DuoVisc和透明质酸钠(其胜)在复杂性白内障超声乳化术中对角膜切口水肿及角膜内皮的影响。方法:将复杂性白内障(抗青光眼术后小瞳孔、陈旧性虹膜炎瞳孔后粘连)106眼,随机分成2组,其中透明质酸钠A组(其胜)53眼;其中抗青光眼术后小瞳孔21眼、陈旧性虹膜炎瞳孔后粘连32眼。DuoVisc组B组53眼;其中抗青光眼术后小瞳孔23眼、陈旧性虹膜炎瞳孔后粘连30眼。两组患者在白内障术前均有青光眼病史(且均有抗青光眼手术史)和陈旧性虹膜炎史。部分患者曾行两次以上抗青光眼手术,所有患者无糖尿病等全身疾病史。采用超声乳化白内障摘除联合折叠人工晶状体植入术,术前术后采用非接触式角膜内皮镜(NONCON ROBO SP60000)于术前、术后1wk和术后1,3mo对角膜内皮细胞进行随访观察,并对中央区0.25mm×0.37mm范围内进行计数密度测量。结果:两组一般情况包括年龄、超声能量与时间的乘积无显著性差异(P>0.05);两组术前测量角膜内皮数无显著性差异(P>0.05);术后1d,1wk角膜水肿的患者B组明显轻于A组(P<0.01);当角膜水肿为(++~+++)时、角膜内皮损伤、丢失的修复在术后1wk,1mo内B组明显优于A组(P<0.01);术后3mo2组比较差异无显著性(P>0.05)。结论:在复杂性白内障超声乳化术中使用粘弹剂DuoVisc对减少角膜术后水肿及对角膜内皮细胞的保护明显优于透明质酸钠(其胜)。     

Effect of 1% sodium hyaluronate (Healon) on a nonregenerating (feline) corneal endothelium

A series of experiments were performed to investigate the effect of 1% sodium hyaluronate (Healon) on the nonregenerating corneal endothelium of the cat. Aqueous humor replacement with 1% sodium hyaluronate resulted in mild, transient elevations of intraocular pressure compared to eyes that were injected with balanced salt solution. Sodium hyaluronate 1% protected the feline endothelium against cell loss incurred by contact with hyaluronate-coated intraocular lenses compared to endothelial contact with lenses that were not coated with sodium hyaluronate. The use of intraoperative 1% sodium hyaluronate, however, did not protect against endothelial cell loss incurred by penetrating keratoplasty or prevent subsequent skin graft-induced corneal homograft rejections. Homograft rejections were milder, however, in some eyes that received grafts coated with 1% sodium hyaluronate. Image analysis of photographs of trypan blue- and alizarin red-stained corneal buttons after trephining, stretching of Descemet's membrane, rubbing against iris-lens preparations, or immediately after penetrating keratoplasty demonstrated that the stretching of the posterior cornea is an important cause of endothelial damage that would not be protected against by a viscoelastic coating.     

Clinical evaluation of endothelial cell decrease with VisThesia in phacoemulsification surgery

PURPOSE: To assess the endothelial cell decrease after the use of sodium hyaluronate 0.3% and lidocaine hydrochloride 2% (VisThesia) to determine whether the addition of lidocaine 1% to sodium hyaluronate 1.5% makes the solution more toxic to the cornea. SETTING: Instituto de Oftalmologia Avanzada, Madrid, Spain, and Unita Operative Oculistica, Cesena, Italy. METHODS: VisThesia is an ophthalmic viscosurgical device (OVD) that incorporates lidocaine 1% to provide better comfort to patients under topical anesthesia. Fifty eyes 50 patients were operated on following the same patient selection and surgical technique. After the povidone-iodine (Betadine) ocular asepsis, 1 full ampoule of VisThesia Topical was applied over the corneal surface. The intracameral product was used as a routine OVD during the phacoemulsification procedure. The endothelium of the central cornea was examined preoperatively and 3 months after surgery using a noncontact endothelium microscope. RESULTS: At the last follow-up visit, the mean best corrected visual acuity was 0.88 +/- 0.18 and the mean manifest SE was -0.36 +/- 1.78 D. The mean endothelial cell density had decreased from 2363.57 +/- 435.4 cells/mm2 preoperatively to 2222.6 +/- 537.69 cells/mm2 at 3 months. These values are comparable with results obtained in other investigations published in the literature using other, similar OVD. CONCLUSIONS: The results observed in this investigation indicate that the addition of lidocaine to the sodium hyaluronate in VisThesia does not induce additional toxicity nor does it result in increased endothelial cell loss when compared with other, similar OVDs.     

超声乳化术中不同粘弹剂(Viscoat和透明质酸钠)对角膜内皮细胞的影响

目的　比较两种粘弹性物质Viscoat和透明质酸钠在白内障超声乳化手术中对角膜内皮的影响。方法　老年性白内障 49人 68眼 ,其中透明质酸钠组 2 5人 3 4眼 ,Viscoat组 2 4人 3 4眼 ,两组患者无内眼病史、眼外伤及眼内手术史 ,无糖尿病等全身疾病史。采用超声乳化术摘出白内障同时植入折叠性人工晶体 ,术前术后用非接触型角膜内皮显微镜观察测量角膜内皮细胞密度。结果　二组一般情况包括年龄 ,晶体核硬度及超声能量与时间的乘积无显著性差异 (P >0 0 5 ) ;透明质酸钠组术前和术后的角膜内皮细胞丢失率为 15 % ,经统计学处理有统计学意义 (P <0 0 5 )。Viscoat组术前和术后的角膜内皮细胞丢失率为 9% ,经统计学处理没有显普性差异 (P >0 0 5 )。结论　在白内障超声乳化手术中粘弹剂Viscoat对角膜内皮细胞的保护能力强于透明质酸钠     

The effect of sodium hyaluronate on the corneal epithelium. An ultrastructural study

The effect of sodium hyaluronate (NaHa) 1% and 0.1% was studied on 14-day chick embryo corneal epithelium by scanning electron microscopy. It was found that NaHa 1% or 0.1% had no toxic effects on the chick corneal epithelium and the normal architecture of the cells and the morphology of the microvilli was well preserved. A combination of NaHa 0.1% and benzalkonium chloride (BAK) 0.01% reduced the toxic effect of BAK on the surface corneal epithelium. NaHa 0.1% provided a better protection of the corneal epithelium against dryness than hydroxyethylcellulose (HEC) 0.1% or phosphate buffer saline (PBS).     

Viscoelastic protection from endothelial damage by air bubbles

PURPOSE: To determine whether viscoelastic materials effectively protect the corneal endothelium from air bubbles. SETTING: Department of Ophthalmology, Yonsei University College of Medicine, Seoul, Korea. METHODS: Human eye-bank and rabbit eyes had a standardized phacoemulsification procedure with or without viscoelastic material (Healon [sodium hyaluronate 1.0%], Healon GV [sodium hyaluronate 1.4%], or Viscoat [chondroitin sulfate 4.0%-sodium hyaluronate 3.0%]). The integrity of the endothelium was examined after the procedure with F-actin staining and scanning electron microscopy. Rabbit eyes with and without viscoelastic material (Healon or Viscoat) had a standardized irrigation/aspiration (I/A) procedure. The mucinous layer of the endothelium was examined after the procedure with transmission electron microscopy. RESULTS: In the phacoemulsification experiment without viscoelastic material, with Healon, and with Healon GV, the endothelium of human and rabbit corneas had many areas of cell loss in a pattern consistent with air-bubble damage. With Viscoat, endothelial cells remained intact. In the I/A experiment, the mucinous layer of Viscoat-exposed rabbit endothelium appeared thinner. In the same experiments without viscoelastic material or with Healon, the mucinous layer of the endothelium appeared normal. CONCLUSIONS: Viscoat effectively protected the endothelium from air-bubble damage. Viscoat appears to protect the endothelium by acting as a physical barrier. Its adherence is probably related to the way it interacts with the mucinous layer of the endothelium.     

不同染色剂对兔眼角膜内皮细胞影响的研究

目的 观察并比较荧光素钠、吲哚靛青绿，台盼蓝，亚甲蓝，龙胆紫5种不同的前囊膜染色剂对兔眼角膜内皮细胞的影响。方法 新鲜离体兔眼角膜内皮滴入各实验试剂，0.25%台盼蓝，0.2%茜素红双重染色，光镜下观察角膜内皮细胞的活性，计数内皮细胞的死亡数，透射电镜检查，观察角膜内皮细胞超微结构的变化。结果 1%亚甲蓝组角膜内皮细胞失去正常的六边形结构，可见较多着色死亡细胞，细胞的死亡率与对照组相比，有统计学差异（P〈0.01）。电镜下，1%亚甲蓝组可观察到内皮细胞的胞膜不完整，胞浆内有空泡形成等变化。结论 1%亚甲蓝溶液对兔眼角膜内皮细胞的损伤作用。     

Effect of intracameral injection of lidocaine and carbachol on the rabbit corneal endothelium

PURPOSE: To determine the effect of intracameral injection of preservative-free lidocaine 1% and carbachol 0.01% on corneal endothelial cells of rabbits. SETTING: Department of Ophthalmology, National Taiwan University Hospital, Taipei, Taiwan. METHODS: Forty eyes of 20 New Zealand White rabbits were divided into 2 equal groups. In the first group, 1 eye was injected with 0.02 mL of preservative-free lidocaine 1% and the fellow eye was injected with 0.02 mL of normal saline as a control. In the second group, 1 eye was injected with 0.02 mL of carbachol 0.01% and the fellow eye was injected with 0.02 mL of normal saline. Specular microscopy was used to evaluate corneal endothelial cell loss and corneal thickness 1 week and 1 month postinjection. For morphologic studies, corneal buttons were excised and stained with alizarin red with trypan blue. Scanning electron microscopy (SEM) examination was performed. RESULTS: Specular microscopy revealed no significant endothelial cell loss and normal endothelial thickness with the intracameral injection of preservative-free lidocaine 1% and carbachol 0.01% compared with the control eye. Alizarin red with trypan blue stain and SEM examinations revealed smooth, distinct, and intact intercellular borders and normal viability of corneal endothelial cells in both groups. CONCLUSIONS: Intracameral injections of preservative-free lidocaine 1% and carbachol 0.01% do not produce morphologic and functional changes in the corneal endothelial cells of rabbits.     

Effects of viscoelastic material on the corneal endothelial cells in trabeculectomy with adjunctive mitomycin-C

We evaluated the change of corneal endothelium after trabeculectomy with mitomycin-C soaking (0.2 mg/ml, 2.4 +/- 1.2 minutes) and the effect of viscoelastic material in reducing this change. In randomly selected cases, 0.05 ml of sodium hyaluronate(Healon) was injected into anterior chamber (Healon group, n = 20), and same amount of balanced salt solution was injected in the other eyes (Control, n = 18) at the beginning of surgery. There were no differences in clinical variables and specular microscopy result between 2 groups before surgery. After surgery, the change of endothelial cells were significantly reduced in Healon group (cell density; -2.5 +/- 1.6%, variability of cell area; 5.8 +/- 2.5%, and percentage of hexagonal cell; -2.2 +/- 0.7%) compared to control group (-7.7 +/- 6.0%, 8.9 +/- 4.4%, and -4.8 +/- 3.5% respectively, p < 0.01). In trabeculectomy with mitomycin-C, the damage to the corneal endothelium was reduced significantly by injecting the viscoelastic material without significant complication.     

Comparison of preservative-free bupivacaine vs. lidocaine for intracameral anesthesia: a randomized clinical trial and in vitro analysis

PURPOSE: To determine whether intracameral bupivacaine hydrochloride 0.5% is as effective as lidocaine hydrochloride 1.0% in controlling discomfort of patients during phacoemulsification and posterior chamber intraocular lens implantation. In rabbits, corneal endothelial cell function, ultrastructure, and viability were evaluated after in vitro perfusion of bupivacaine 0.5%. METHODS: In a double-masked, controlled trial, 48 eyes of 48 patients with uncomplicated age-related cataract were randomly assigned to receive bupivacaine 0.5% or lidocaine 1.0% intracamerally before phacoemulsification with a posterior chamber intraocular lens. Outcome measures such as pain, visual acuity, amount of sedation, length of surgery, pupil size, intraocular pressure, corneal clarity, and anterior chamber reaction were compared. In laboratory studies, paired rabbit corneas were evaluated by endothelial cell perfusion with either bupivacaine 0.5%, bupivacaine 0.5% and glutathione bicarbonate Ringer solution in a 1:1 ratio or bupivacaine 0.5% buffered to a pH of 7.0. The paired control corneas were perfused with glutathione bicarbonate Ringer solution and rates of corneal swelling were determined. Cell ultrastructure and viability were also evaluated. RESULTS: In the randomized trial, there was no significant difference in the pain patients had during surgery or in the early or late postoperative period. No statistically significant difference was seen between the two groups in terms of pupil size, intraocular pressure, corneal edema, anterior chamber reaction, or visual acuity immediately after the operation or on postoperative day 1. Paired rabbit corneas perfused with bupivacaine 0.5% and bupivacaine 0.5% buffered to a pH of 7.0 swelled significantly (P<.001, P = .009, respectively), and had corneal endothelial cell damage. Dilution of the bupivacaine 1:1 with glutathione bicarbonate Ringer solution prevented corneal edema and damage to the corneal endothelium. Endothelial cell viability was also decreased after perfusion of bupivacaine 0.5% (P<.001). CONCLUSIONS: Clinically, bupivacaine 0.5% is as effective as lidocaine 1.0% for anesthesia during phacoemulsification and posterior chamber intraocular lens implantation. However, in vitro perfusion of bupivacaine 0.5% damaged the corneal endothelium of rabbits except when the drug was diluted 1:1 with glutathione bicarbonate Ringer solution. Surgeons who use 0.2 to 0.5 ml of intracameral bupivacaine 0.5% should be aware of its potential to cause endothelial cell damage because of its lipid solubility. The bupivacaine 0.5% should be diluted at least 1:1 with balanced salt solution before intracameral injection, followed immediately by phacoemulsification. The surgeon should ensure that the bupivacaine 0.5% is nonpreserved and packaged in single-use vials or flip-top containers.     

Biochemical studies on the use of sodium hyaluronate in the anterior eye segment. IV. The protective efficacy of the corneal endothelium

We devised an apparatus to add constant mechanical force to the corneal endothelium, and the protective efficacy of sodium hyaluronate to the corneal endothelium was determined quantitatively using an image analyzer. When the corneal endothelium was coated with a 1% solution of 800K or 2150K sodium hyaluronate, the damaged area was significantly less than cases having a coating with a 1% solution of 200K sodium hyaluronate or phosphate buffered saline which was the solvent of sodium hyaluronate. The water uptake of damaged cornea was also investigated using tritiated water. The cornea coated with 800K or 2150K sodium hyaluronate showed the same water uptake as the normal cornea, but the cornea coated with 200K sodium hyaluronate or phosphate buffered saline showed a significantly higher uptake. These results suggest that a 1% solution of 800K or 2150K sodium hyaluronate protects the corneal endothelium from mechanical damages.     

Hyaluronic acid combined with mannitol to improve protection against free-radical endothelial damage: experimental model

PURPOSE: To evaluate the protective properties of combined sodium hyaluronate 2% and mannitol 0.5% (Visiol) on the corneal endothelium in the presence of oxidative stress induced by hydrogen peroxide (H(2)O(2)). SETTING: Instituto Oftalmológico de Alicante, Universidad Miguel Hernández, Alicante, Spain. METHODS: This was an exploratory randomized controlled parallel-group, masked-assessor study of 3 sodium hyaluronate-based ophthalmic viscosurgical devices (OVDs): Visiol, Healon (sodium hyaluronate 1%), and Viscoat (sodium hyaluronate 3%-chondroitin sodium 4%). The OVDs were tested for protective effects on the endothelium following oxidative stress induced by H(2)O(2) at increased concentrations: control (lactated Ringer's solution), 1 mM, 10 mM, and 100 mM. Groups without OVD were used as controls at the same concentrations of peroxide. Each animal received the same treatment in both eyes (10 eyes per group). Endothelial cell lesion was assessed using the Janus green photometry absorbance technique. RESULTS: At 10 mM peroxide concentration, the value of endothelial cell lesion was significantly lower in the Visiol (16.8%, P=.0056), Healon (22.2%, P=.0302), and Viscoat (21.6%, P=.0336) groups than in the control group (29.4%, no OVD). There was a trend in favor of Visiol to more efficiently reduce cell lesions of the endothelium, than Healon (P=.055) and Viscoat (P=.1013). Values of endothelial cell lesion at peroxide concentrations of 1 mM and 100 mM showed the same trends than those observed at 10 mM. CONCLUSIONS: All of the OVDs tested efficiently reduced endothelial lesions against free radicals compared with the control group in which no OVD was used. The following sequence for the efficacy of endothelial cell protection was established: Visiol>Viscoat>Healon>no OVD.     

Comparison of BD Multivisc with the soft shell technique in cases with hard lens nucleus and Fuchs endothelial dystrophy

PURPOSE: To compare the efficacy of 2.5% sodium hyaluronate (BD Multivisc) with the soft shell technique in reducing corneal endothelial cell damage during cataract phacoemulsification in patients with hard lens nucleus (3+) and cornea guttata. METHODS: Thirty patients (37 eyes) scheduled for cataract surgery at Department of Ophthalmology and Visual Sciences, University Hospital San Raffaele, Milano, Italy. Thirty-seven eyes (randomly divided into Groups A and B) with hard lens nucleus (grade 3 or higher) and cornea guttata had phacoemulsification using the soft shell technique (Group A) with Biolon (sodium hyaluronate 1%) and Viscoat (sodium hyaluronate 3%-chondroitin sulfate 4%) or with BD Multivisc alone (Group B). Patients were evaluated preoperatively and after 1, 15, 90, and 180 days, checked for best-corrected visual acuity (BCVA), intraocular pressure (IOP), central corneal thickness, and corneal endothelial density. Stop and chop phacoemulsification technique, with burst mode (Alcon Legacy 20000, Advantec), was performed. RESULTS: There were no significant differences between the two groups at 3 and 6 months in BCVA, IOP, corneal thickness, or endothelial cell density. The increase of central corneal thickness (preoperative: Group A 584+/-30 microm, Group B 573+/-30 microm; postoperative at 90 days: Group A 593+/-38 microm, Group B 577+/-25 microm) was not significant. Endothelial cell loss was similar in both groups. CONCLUSIONS: The results suggest that the soft shell technique (Biolon, Viscoat) and 2.5% sodium hyaluronate (BD Multivisc) are both effective in protecting the corneal endothelium in Fuchs dystrophy during phacoemulsification in patients with hard lens nucleus.     

Corneal endothelial loss with new intraocular lenses

When we compared the effect of a hydrogel intraocular lens on the corneal endothelium of rabbits to the damage produced by uncoated methylmethacrylate intraocular lenses and methylmethacrylate lenses coated with sodium hyaluronate or methylcellulose, we found that the endothelial damage produced by the hydrogel lenses in a standard 0.25 mm2 of contact was 3.6%. This value was not significantly different from that for the control corneas (0.4%). Uncoated methylmethacrylate lenses caused 62% endothelial loss but coating them with sodium hyaluronate or methylcellulose reduced the loss to 27% and 57% respectively. The results suggested that a hydrogel intraocular lens produces minimal endothelial damage and that coating a methylmethacrylate lens with sodium hyaluronate or methylcellulose does not provide reliable endothelial protection.     

Corneal endothelial toxicity of different lidocaine concentrations

PURPOSE: To examine the potential damaging effect on the corneal endothelium of unpreserved lidocaine in concentrations of 1%, 5%, and 10%. SETTINGS: Department of Ophthalmology, Charité Medical Faculty, Humboldt University, Berlin, Germany. METHODS: Experimental porcine corneas (n = 18) were exposed to 100 microL of unpreserved lidocaine hydrochloride at concentrations of 1%, 5%, and 10% for 60 minutes. Additional corneas (n = 6) were treated with lidocaine hydrochloride 1% for 30 minutes to simulate clinical conditions. Balanced salt solution (BSS((R))) served as a control to evaluate corneal endothelial cell damage using Janus Green photometry. Morphology, damage pattern, and changes in the ultrastructural appearance of corneal endothelial cells were examined by light and scanning electron microscopy. RESULTS: Lidocaine 1% used for 30 or 60 minutes did not cause significantly more corneal endothelial damage (mean 3.00% +/- 0.76% [SD] and 3.26% +/- 1.00%, respectively) than in the control group (mean 3.32% +/- 0. 86%) (P >.01). Significant corneal endothelial cell loss was observed with lidocaine 5% (mean 10.7% +/- 6.4%) (P <.001) and lidocaine 10% (42.3% +/- 17.0%) (P <.001). CONCLUSION: Experimental exposure of corneal endothelial cells to higher concentrations of lidocaine resulted in significant cell loss, indicating that the 1% concentration only should be used clinically.     

The morphology and function of healing cat corneal endothelium

We mechanically damaged the entire corneal endothelium of one eye of each of ten cats and then examined both eyes by fluorophotometry and specular microscopy for 5 months. Six weeks after damage, when the corneas had cleared sufficiently to make accurate measurements, the mean endothelial permeability to carboxyfluorescein was increased 11% (P = 0.02) and the mean central corneal thickness was increased 11% (P = 0.05) in the damaged eyes. The mean endothelial pump rate was decreased 29% (P = 0.05), indicating that the increase in permeability was insufficient to explain the increase in thickness. The permeability returned to normal by 3 months and the pump rate by 5 months. Six weeks after damage, the mean endothelial cell size was increased 89% (P less than 0.01), the mean coefficient of variation of cell size was increased 200% (P less than 0.01), and the mean percentage of hexagonal cells was decreased 34% (P less than 0.01). By 5 months, the mean cell size had changed very little, and none of the three morphologic measurements had returned to normal. As in rabbits, the endothelial barrier in cats recovers before the pump after wounding. Unlike in rabbits, functional recovery in cats requires at least several months. Such prolonged functional recovery after endothelial trauma might also be expected in humans who, like cats and unlike rabbits, have little capacity for endothelial mitosis during healing.     

Effect of indocyanine green intraocular stain on human and rabbit corneal endothelial structure and viability. An in vitro study

PURPOSE: To evaluate the direct effect of intraocular indocyanine green (ICG) on endothelial cell function, ultrastructure, and viability in human and rabbit corneas. SETTING: A laboratory evaluation study. METHODS: Paired human and rabbit corneas were mounted in an in vitro specular microscope for endothelial cell perfusion. One corneal endothelium was perfused with 25 mg ICG dissolved in 0.5 mL aqueous solvent in 4.5 mL balanced salt solution (BSS(R)) for 3 minutes followed by washout with a control solution. The percentage of ICG exposed to the corneal endothelium was 0.5%. The paired cornea was perfused with the same solution without ICG, followed by the washout. The corneas were fixed for scanning and transmission electron microscopy (TEM). In another group, the endothelial viability was determined using a live cell/dead cell assay. RESULTS: In rabbit corneas, the mean corneal swelling rate was 12.9 microm/h +/- 1.2 (SEM) in the ICG corneas and 2.8 +/- 1.9 microm/h in the controls. Scanning electron microscopy and TEM revealed a normal endothelial cell mosaic. The control electron micrographs were similar. In human corneas, the mean swelling rate was 19.1 +/- 2.8 microm/h in the ICG corneas and 19.2 +/- 2.6 microm/h in the controls. Scanning electron microscopy and TEM revealed intact junctions with slight cellular vacuolization, similar to that in the controls. In the live cell/dead cell subgroup, the mean damage was 17.3% +/- 1.7% in the ICG-exposed corneas and 22.0% +/- 8.9% in the controls. CONCLUSIONS: Three-minute exposure to ICG in BSS had no adverse effect on corneal endothelial function, ultrastructure, or viability in human and rabbit corneas. This study provides a safety profile for the corneal endothelium when ICG is used as an intraocular tissue stain in ophthalmic surgery.     

The effect of intraocular lidocaine in white rabbit eyes

PURPOSE: Recently, intraocular lidocaine anesthesia has been used in cataract surgery. We studied the toxicity of intraocular unpreserved lidocaine for corneal endothelial cell and retina using Japanese white rabbits. METHOD: They were divided into two groups. One group was injected intracamerally and the other group was injected intravitreally with 0.2 ml of unpreserved lidocaine of 0%, 0.02%, 0.2%, or 2% concentration. The number of corneal endothelial cells was measured 1 week after the injection. The rabbits were killed after measurements, and their corneas were studied histologically. The retina was examined by electroretinogram from before the injection through 1 week after the injection. RESULTS: There was no significant change in number of corneal endothelial cells after injection of 0.2% lidocaine. However, histological abnormality was seen in corneal endothelial cells after 2% lidocaine injection. There was also significant change in electroretinogram with 2% lidocaine injection. No histological abnormality was seen in the retina 1 week after the injection. CONCLUSION: The rabbit cornea and retina manifested no serious changes after the injection of lidocaine at less than 0.2% concentration functionally and histologically.