Viscous corneal protection by sodium hyaluronate, chondroitin sulfate, and methylcellulose

The authors' study of the viscosities of various concentrations of sodium hyaluronate, chondroitin sulfate, and methylcellulose revealed that sodium hyaluronate and methylcellulose are pseudoplastic fluids in contrast to chondroitin sulfate, which is a Newtonian fluid. Pseudoplastic fluids are ideal for maintaining the anterior chamber, since they are more viscous at rest. Intermediate viscosity preparations of these three agents used as a thin endothelial coating gave excellent protection from intraocular lens abrasion. A highly viscous agent, eg, sodium hyaluronate 1%, in a thin layer produced extensive endothelial cell damage because it transmitted excessive shear force to the endothelium. A highly viscous agent, sodium hyaluronate 1% in a thick layer produced a physical barrier to compression with little endothelial damage. A low-viscosity agent, balanced salt solution provided insufficient protection against intraocular lens abrasion.     

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.     

The use of hydroxypropyl methylcellulose in extracapsular cataract extraction with intraocular lens implantation

We conducted a prospective randomized clinical trial on the use of 2% hydroxypropyl methylcellulose and 1% sodium hyaluronate in the anterior chamber during anterior capsulotomy and nuclear expression in extracapsular cataract extraction with posterior chamber lens implantation in 70 patients. Both viscoelastic substances helped maintain the anterior chamber and facilitated the operation, although sodium hyaluronate was preferred. There was no excessive intraocular inflammation or toxicity noted with either agent. Patients given sodium hyaluronate had a larger increase in intraocular pressure during the early postoperative period (2.04 mm Hg) than did those given hydroxypropyl methylcellulose (1.1 mm Hg), but the difference was not significant. Nine weeks after surgery, the mean (+/- SD) central endothelial cell loss was 4.84% (+/- 7.26%) in the 17 eyes with sodium hyaluronate and 4.37% (+/- 9.84%) in the 53 eyes with hydroxypropyl methylcellulose. The intraocular pressure and corneal thickness were not significantly different before operation and nine weeks after it.     

Comparison of 2% hydroxypropyl methylcellulose and 1% sodium hyaluronate in implant surgery

We conducted a prospective randomized clinical trial of 2% hydroxypropyl methylcellulose and 1% sodium hyaluronate (Healon) in routine extracapsular cataract surgery with implantation of a posterior chamber intraocular lens. Of the 84 patients 40 received methylcellulose and 44 received sodium hyaluronate. There was no statistically significant difference in endothelial-cell loss or induced cellular polymegathism between the two groups. The intraocular pressure before and after surgery was similar in the two groups, as was the visual acuity 8 weeks after surgery. The results suggest that 2% hydroxypropyl methylcellulose is a safe and effective alternative to 1% sodium hyaluronate in routine implant surgery.     

The effects of sodium hyaluronate, chondroitin sulfate, and methylcellulose on the corneal endothelium and intraocular pressure

Sodium hyaluronate (Healon), chondroitin sulfate, and methylcellulose have been used to protect the corneal endothelium from intraocular lens trauma. A study of the efficacy and toxicity of these compounds showed that 1% sodium hyaluronate, 0.4% methylcellulose, and 20% chondroitin sulfate were nontoxic to the corneal endothelium, but that 20% chondroitin sulfate caused a marked decrease in corneal thickness because of its hypertonicity. Anterior chamber injection of these viscous substances resulted in an increase in intraocular pressure. Within one to four hours the maximum intraocular pressure with 1% sodium hyaluronate was 67 +/- 4.1 mm Hg and that with 20% chondroitin sulfate was 55 +/- 3.5 mm Hg. The intraocular pressure did not increase to these high levels with 10% chondroitin sulfate or 0.4% methylcellulose or when the test substances were washed out of the anterior chamber. The corneal endothelium was protected from injury with 1% sodium hyaluronate and 20% chondroitin sulfate, but 10% chondroitin sulfate and 0.4% methylcellulose provided only minimal protection.     

2% hydroxypropyl methylcellulose as a viscous surgical adjunct. A multicenter prospective randomized trial.

A multicenter prospective trial was conducted comparing preoperative and postoperative endothelial cell counts in patients who had extracapsular cataract extraction with posterior chamber lens implantation or phacoemulsification and posterior chamber lens implantation. One hundred sixty six eyes received 2% hydroxypropyl methylcellulose (Occucoat) and 56 eyes received sodium hyaluronate (Healon). The average cell loss in the Occucoat group was 12.1%; in the Healon group it was 10% (P = NS). There was no significant difference between the two groups in intraocular pressure at 24 hours. In this study Occucoat was as effective in protecting the corneal endothelium as Healon.     

Effect of Healon5 and 4 other viscoelastic substances on intraocular pressure and endothelium after cataract surgery

PURPOSE: To compare the ophthalmic viscoelastic device (OVD) Healon5 (sodium hyaluronate 2.3%) with 4 other commonly used OVDs during phacoemulsification and intraocular lens implantation in terms of influence on intraocular pressure (IOP) postoperatively and endothelial cells preoperatively and postoperatively. SETTING: Department of Ophthalmology, Ruprecht-Karls-University Heidelberg, Germany. METHODS: This clinical randomized prospective study, in which patients and observer were masked, comprised 81 eyes. Seventy-four eyes (mean patient age 71.2 years +/- 7.8 [SD]) completed all preoperative and 5 postoperative examinations. The OVDs used were OcuCoat and Celoftal (hydroxypropyl methylcellulose 2.0%), Viscoat (sodium hyaluronate 3.0%-chondroitin sulfate 4.0%), Healon GV (sodium hyaluronate 1.4%), and Healon5 (sodium hyaluronate 2.3%). Intraocular pressure was measured by standard Goldmann applanation tonometry preoperatively and 4 to 6 and 24 hours and 7, 30, and 90 days postoperatively. Endothelial cell counts were done preoperatively and 90 days postoperatively using a Pro/Koester WFSCM contact endothelial microscope. Exclusion criteria were IOP greater than 21 mm Hg at the preoperative examination, age younger than 40 years, significant corneal pathology, and a history or presence of uveitis or pseudoexfoliation syndrome. RESULTS: All groups had increased IOP 4 hours postoperatively. The Healon5 group had the highest mean pressure (24.9 mm Hg) followed by the Viscoat group (23.6 mm Hg). The mean IOP in the other OVD groups was less than 22.1 mm Hg. These differences were not significant. Twenty-four hours postoperatively and at all subsequent examinations, mean IOP was below 20 mm Hg. The Healon5 group had the lowest mean endothelial cell loss (6.2%), significantly lower than in the other groups (P < .02). CONCLUSION: With all 5 OVDs, endothelial cell loss was found, with the lowest in the Healon5 group, and IOP was increased 4 to 6 hours postoperatively. After 24 hours, no significant increases in IOP were noted.     

Comparison of the effects of viscoelastic agents on clinical properties of the Unfolder lens injection system.

PURPOSE: To evaluate the effect of 7 viscoelastic materials on the physical properties of the Unfolder lens injection system. SETTING: John A. Moran Eye Center, University of Utah School of Medicine, Salt Lake City, Utah, USA. METHODS: New sterile SI-40NB intraocular lenses (IOLs) were loaded into the Unfolder (AMO PhacoFlex II SofTip insertion system (Allergan) using 7 viscoelastic materials: sodium hyaluronate 1.0% (Healon, Provisc), sodium hyaluronate 1.4% (Healon GV), sodium hyaluronate 1.6% (Amvisc Plus), hydroxypropyl methylcellulose 2.0% (Occucoat), sodium chondroitin 4.0%--sodium hyaluronate 3.0% (Viscoat), and hyaluronate 3.0% (Vitrax). The IOLs were then injected after 10 or 120 seconds in the chamber (chamber dwell time) and 10, 60, or 180 seconds in the barrel of the Unfolder cartridge (barrel dwell time). Torque values (g/cm) required to extrude the lenses were measured with a torque gauge, and the cartridges and IOLs were inspected for damage. RESULTS: Longer chamber dwell times resulted in lower torque values to extrude the IOLs (P < .001). Conversely, longer barrel dwell times resulted in higher torque requirements for IOL extrusion (P < .001). Furthermore, rates of adverse events, such as nondelivery, IOL damage, or Unfolder cartridge damage, were higher with shorter chamber dwell times and longer barrel dwell times (P < .001). However, IOL damage was avoided when the manufacturer's recommended chamber and barrel times were used. CONCLUSION: Increasing chamber dwell time and decreasing barrel dwell time resulted in lower torque values to extrude IOLs from the Unfolder and increased successful use. Moreover, dispersive viscoelastic agents tended to be more forgiving of changing dwell times and therefore had lower torque values and adverse event rates overall.     

Comparison of the effect of sodium hyaluronate (Ophthalin) and hydroxypropylmethylcellulose (HPMC-Ophtal) on corneal endothelium, central corneal thickness, and intraocular pressure after phacoemulsification

PURPOSE: To prospectively evaluate the effects of 2% hydroxypropyl-methylcellulose (HPMC-Ophtal) and sodium hyaluronate 1% (Ophthalin) on intraocular pressure, corneal thickness, and endothelial cell loss in small incision cataract surgery with implant. METHODS: A total of 110 patients undergoing routine phacoemulsification with implant received either 2% hydroxypropyl methylcellulose or sodium hyaluronate 1% as ophthalmic viscosurgical device. Pre- and postoperative slitlamp examination, intraocular pressure measurement (preoperatively and at 1-4 hours, 1 day, and 7 days postoperatively), ultrasonic pachymetry (preoperatively and at 1 week, 4-6 weeks, and 12 weeks post operatively), and corneal endothelial cell count (preoperatively and 12 weeks postoperatively) were performed. Data were analyzed using two-way analysis of variance. RESULTS: All measurements were comparable between the two groups preoperatively. Intraocular pressure was significantly lower in the Ophthalin group at 1 day post operatively, while no significant difference was found between the two groups on the 1-4 hours and 7 days examination. The central corneal thickness was not significantly different between the two groups at any postoperative visit . However, the mean cell density demonstrated a significant fall of 11.76% for Ophthalin and 4.27% for HPMC-Ophtal at 12 weeks post-operatively, the difference between the two being significant (p=0.009). CONCLUSIONS: 2% Hydroxypropyl methylcellulose, compared with sodium hyaluronate 1%, is superior in protecting the corneal endothelial cells, has the same effect on central corneal thickness, and is associated with slightly higher intraocular pressure 1 day post operatively. It compares favorably with sodium hyaluronate 1% and can be used as an effective and cheaper alternative in routine small incision cataract surgery with implant.     

Comparison of sodium hyaluronate and methylcellulose in extracapsular cataract extraction

Extracapsular cataract surgery with posterior chamber lens implantation was performed in a total of 30 patients. These were randomly divided into two groups. In one group sodium hyaluronate 1% (Healon) was used as a tool in surgery, in the other group methylcellulose 2% was used. The viscous substances were irrigated out of the eyes at the conclusion of surgery. Central corneal thickness, intraocular pressure, and aqueous flare were recorded until one month post-operatively. There was no difference in corneal thickness between the two groups. The mean intraocular pressure was lower than pre-operatively in both groups with a lower pressure in the methylcellulose group compared to the sodium hyaluronate group during the first part of the observation period.     

Conditioning of hydrogel lenses by a multipurpose solution containing an ocular lubricant.

PURPOSE: The addition of the ocular lubricant hydroxypropyl methylcellulose (HPMC) to a multipurpose contact lens solution conditions the hydrogel lens surface. This investigation reports the clinical benefits to contact lens wearers and the improved physical properties of the solution with HPMC added. METHODS: One-hundred forty-seven subjects wearing a variety of hydrogel lenses used a multipurpose solution with and without addition of HPMC and were assessed for product comfort and preference. In the laboratory, conditioning by HPMC was demonstrated in fluid coating, dynamic contact angle, uptake of fluid on hydrogel lenses, and release of HPMC from lenses after soaking. RESULTS: Lens wearers reported the multipurpose solution with HPMC more comfortable, including measures relating to maintaining lens moisture over time. The multipurpose solution with HPMC produced a thicker and longer-lasting layer of fluid on hydrogel lenses and other plastics than other multipurpose solutions. HPMC was found to adsorb to both group 1 and 4 lens materials and release gradually, with detectable amounts releasing from the lens beyond 12 hours. CONCLUSIONS: The conditioning properties of the multipurpose solution with HPMC produce improved wetting of lenses and enhanced lens wearing comfort. Binding of HPMC to the lens surface and subsequent time-release is the probable mechanism for these benefits.     

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.     

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     

Comparison of the effect of polymethylmethacrylate and silicone intraocular lenses on rabbit corneal endothelium in vitro

An in vitro comparison of corneal endothelial damage caused by polymethylmethacrylate and by silicone intraocular lenses was made. Endothelial damage was assessed by vital staining of corneal endothelium immediately following direct contact with an intraocular lens. Silicone lenses produced less damage than polymethylmethacrylate lenses. The difference could be attributed to a specific type of damage-membrane stripping-seen only after contact with polymethylmethacrylate lenses.     

Neodymium:YAG laser interaction with Alcon IOGEL hydrogel intraocular lenses: an in vitro toxicity assay

The objective of this study was to determine the potential toxicity generated by the interaction of the Nd:YAG laser and Alcon IOGEL intraocular hydrogel lens material. The IOGEL lens is composed of poly 2-hydroxyethylmethacrylate, containing 38% water, previously shown to be highly biocompatible in a wide range of tissue culture and implantation experiments. In this study, intraocular lenses (IOLs) immersed in serum-free cell culture medium were purposely exposed to exaggerated doses of laser energy to cause extensive damage. An IOLAB polymethylmethacrylate (PMMA) lens served as a control lens material. The resultant solutions were assayed for cytotoxicity in a bioassay system using fourth passage human corneal endothelial cells. No cytotoxicity was seen in the bioassay for the IOGEL hydrogel IOLs or the PMMA control IOL at any laser range/dosage tested over a 72-hour incubation period. Hydrogel lenses exhibited decreasing yellowing with decreasing energy levels, and no lens discoloration was apparent at the lowest level of irradiation, 5 mJ/50 laser bursts; the PMMA control lens exhibited moderate yellowing at 15 mJ/50 bursts. Lens marking was moderate for all IOGEL IOLs; the PMMA lens marking was severe at the power level tested.     

Postoperative pressures after phacoemulsification: sodium hyaluronate vs. sodium chondroitin sulfate-sodium hyaluronate

This randomized study of 100 patients compared the effects of two viscoelastic agents on intraocular pressure after phacoemulsification cataract extraction with intraocular lens implantation. In 50 patients, sodium hyaluronate was instilled in the anterior chamber before lens insertion and then evacuated. Sodium chondroitin sulfate-sodium hyaluronate was instilled in another 50 patients and was not evacuated. Postoperative intraocular pressure increases occurred much less frequently (6% versus 54%) and were milder in the group that received sodium chondroitin sulfate-sodium hyaluronate. Mean peak intraocular pressure was reached at 16 hours in both groups; peak pressure was 31.7% higher in the group that received sodium hyaluronate. Better clearance from the eye due to the lower molecular weight of sodium chondroitin sulfate-sodium hyaluronate may explain the differences in intraocular pressures between the groups.     

Efficacy of polyacrylamide vs. sodium hyaluronate in cataract surgery

A prospective randomized study was conducted in 137 patients who underwent cataract surgery and implantation of a polymethylmethacrylate intraocular lens with either polyacrylamide (Orcolon) (68 patients) or sodium hyaluronate (Healon) (69 patients) as the viscoelastic material. Both viscoelastics were aspirated at the end of surgery. Patients were examined before surgery and 1 and 14 days after surgery. Endothelial cell counts were obtained before surgery and 3 months after surgery in 34 patients (16 in the polyacrylamide group and 18 in the sodium hyaluronate group). There were no reports of a flat or shallow anterior chamber intraoperatively in either group. There was no statistically significant difference between the two groups in the incidence of corneal edema or iritis on any visit or in endothelial cell loss. Although there was a significant reduction in intraocular pressure across postoperative visits for the overall sample, there was no significant difference in pressure between the polyacrylamide and sodium hyaluronate groups. The results indicate that no untoward effects on corneal edema, endothelial cell count, iritis or intraocular pressure are to be expected when polyacrylamide is used as an aid to cataract surgery.     

Efficacy and safety of the soft-shell technique in cases with a hard lens nucleus

PURPOSE: To evaluate the efficacy and safety of the soft-shell technique in reducing corneal endothelial cell damage during cataract surgery in patients with a hard lens nucleus. SETTING: Miyata Eye Hospital, Miyakonojo, Miyazaki, Japan. METHODS: Sixty eyes of 57 cataract patients with a hard lens nucleus (Emery-Little classification grade 3 or higher) had phacoemulsification using the soft-shell technique with Healon((R)) (sodium hyaluronate 1%) and Viscoat (sodium hyaluronate 3.0%-chondroitin sulfate 4.0%) (soft-shell group) or with Healon alone (control group). The visual acuity, intraocular pressure (IOP), flare intensity in the anterior chamber, central corneal thickness, and corneal endothelial cell density were evaluated postoperatively. RESULTS: There were no significant IOP elevations in either group. The mean central corneal thickness in the control group was 539 microm +/- 26.0 (SD) preoperatively and 578 +/- 52.0 microm 1 day after surgery; the increase was significant (P =.0154). There was no significant change in the central corneal thickness in the soft-shell group. There were no statistically significant differences between the 2 groups in uncorrected visual acuity, best corrected visual acuity, IOP, flare intensity in the anterior chamber, and central corneal thickness throughout the follow-up. The rate of endothelial cell loss 3 months after surgery was 6.4% +/- 9.6% in the soft-shell group and 16.3% +/- 9.8% in the control group (P =.0003). CONCLUSION: The results suggest that the soft-shell technique is safe and effective in protecting corneal endothelial cells during cataract surgery in patients with a hard lens nucleus.     

Dry coating of intraocular lenses with bovine submaxillary mucin.

Uncoated intraocular lenses caused extensive corneal endothelial cell damage after in vitro contact (mean, 30.9% cell loss), whereas lenses coated with bovine submaxillary mucin type 1 caused minimal cell loss (mean 4.3%). No observable in vivo toxicity in the eye occurred when 0.1 ml of 3, 6, or 9% solution was injected into the anterior chamber. Mucin-coated lenses can be sterilized by ethylene oxide with no measurable adsorbence into the coating. Scanning electron microscopy confirmed the results from vital staining.     

Endothelial cell loss after phacoemulsification and insertion of silicone lens implants

Central corneal endothelial cell loss was compared following primary insertion of folded posterior chamber silicone intraocular lenses (IOLs) in 29 eyes and Sinskey-style polymethylmethacrylate posterior chamber IOLs in 20 eyes. Cataracts were removed by phacoemulsification and sodium hyaluronate was used in all cases. The mean follow-up time was greater than seven months. The average cell loss was 9.6% and 10.9%, respectively. There was no significant difference in cell loss or visual results in the two groups. The amount of cell loss compares favorably with other series in which cell loss was determined following cataract surgery with and without IOL implantation.