Quantitative assessment of ophthalmic viscosurgical device retention using in vivo confocal microscopy

PURPOSE: To develop and apply a new laboratory method for in vivo quantitative assessment of the retention of ophthalmic viscosurgical devices (OVDs) following phacoemulsification. SETTING: Department of Ophthalmology, University of Texas Southwestern Medical Center, Dallas, Texas, USA. METHODS: Studies of both eyes of New Zealand White rabbits were performed. Six OVDs were evaluated: Provisc and Healon (both sodium hyaluronate 1%), Healon5 (sodium hyaluronate 2.3%), Amvisc Plus (sodium hyaluronate 1.6%), Viscoat (sodium hyaluronate 3%-chondroitin sulfate 4%), and a new viscous-dispersive OVD, DisCoVisc (sodium hyaluronate 3%-chondroitin sulfate 4%). The OVD was injected to fill the anterior chamber and a phacoemulsification needle inserted with the tip positioned just anterior to the lens capsule. Simulated phacoemulsification was performed for 1 minute using flow rates of 20, 40, and 60 mL/min; a vacuum level of 300 mm Hg; and ultrasound power of 60% using a Legacy phacoemulsification unit. The needle was removed, and silicone oil (1000 centistokes) was injected into the anterior chamber. The distance between the corneal endothelium and the OVD-silicone oil interface was measured using in vivo confocal microscopy through-focusing (CMTF). RESULTS: Significant differences in residual thickness were found between the OVDs tested. Specifically, the residual thickness of both DisCoVisc (mean 324.5 microm +/- 163.7 [SD]) and Viscoat (251.4 +/- 100.9 microm) was significantly greater than that of Provisc (9.5 +/- 16.7 microm), Healon (3.8 +/- 11.3 microm), Healon5 (0.6 +/- 2.4 microm), and Amvisc Plus (65.6 +/- 134.0 microm) (P < .05, Dunn test). Ophthalmic viscosurgical device retention was greatest with DisCoVisc; however, there was no statistically significant difference between DisCoVisc and Viscoat in residual thickness. The flow rate did not have a significant effect on the residual thickness (Friedman 2-way analysis of variance by ranks). CONCLUSIONS: Residual OVD thickness following simulated phacoemulsification could be quantitatively measured using in vivo CMTF. The results are consistent with human surgical experience in that the dispersive OVD (Viscoat) was better retained than the cohesive compounds. DisCoVisc, a new viscous-dispersive OVD, also showed retention compared with Viscoat under the experimental conditions.     

Alteration of free radical development by ophthalmic viscosurgical devices in phacoemulsification

PURPOSE: To determine the effect of ophthalmic viscosurgical devices (OVDs) and irrigation/aspiration (I/A) settings on free radical development during phacoemulsification. SETTING: Department of Ophthalmology, Nippon Medical School, Tokyo, Japan. METHODS: Free radicals were detected by the electron spin resonance (ESR) spin-trap method. After a spin-trapping agent, 5,5-dimethyl-1-pyrroline N-oxide 1%, was mixed with the irrigating solution, phacoemulsification simulation was performed in an eye model at 100% ultrasound power levels for 10, 20, and 30 seconds. A high I/A setting (35 mL/min with 250 mm Hg vacuum) and a low I/A setting (15 mL/min with 60 mm Hg vacuum) were used in combination with no OVD, sodium hyaluronate 1% (Healon), sodium hyaluronate 2.3% (Healon5), sodium hyaluronate 3%-chondroitin sulfate 4% (Viscoat), or sodium hyaluronate 1% (Opegan). Immediately after phacoemulsification, the solution in the anterior chamber was collected and signals from the spin adduct were measured using an ESR spectrometer. RESULTS: With the low setting, all OVDs significantly suppressed the signals for up to 20 seconds. At 30 seconds, the signals were still significantly smaller in all OVD groups, except Healon, than those in the no-OVD. With the high setting, the effect was not significant in the Healon and Opegan groups at 10 seconds; by 20 seconds and after, only Viscoat showed significant suppression. CONCLUSIONS: Free radical development in phacoemulsification can be altered by OVD properties and I/A settings. To reduce oxidative stress to the corneal endothelium, attention should be paid to the retention of OVDs in the anterior chamber during phacoemulsification.     

Retention and removal of a new viscous dispersive ophthalmic viscosurgical device during cataract surgery in animal eyes

AIMS: To assess the retention and removal properties of a new viscous dispersive ophthalmic viscosurgical device (OVD), DisCoVisc, in comparison with those of cohesive (Provisc), dispersive (Viscoat), and viscoadaptive (Healon5) OVDs. METHODS: In 20 porcine eyes, cataract surgery was simulated using one of the four OVDs which were stained with fluorescein for better visualisation. Three parameters were measured. Firstly, the presence/absence of OVDs in the chamber at the completion of phacoemulsification was recorded. Secondly, the time until the OVDs were completely removed from the anterior chamber using the phaco needle was measured. Thirdly, after intraocular lens (IOL) implantation, the time needed to completely remove the OVDs from the chamber with irrigation/aspiration tip was recorded. RESULTS: At the completion of phacoemulsification, the OVDs retained in 0% (0/5) for Provisc, 80% (4/5) for Healon5, 100% (5/5) for DisCoVisc, and 100% (5/5) for Viscoat. The retention of OVDs during phacoemulsification was greatest with Viscoat followed by, in descending order, DisCoVisc, Healon5, and Provisc. The removal of OVDs after IOL implantation took longest with Viscoat followed by Healon5, DisCoVisc, and Provisc. CONCLUSION: The viscous dispersive DisCoVisc showed excellent retention during phacoemulsification, while its removal after IOL implantation was very easy. When compared with the viscoadaptive Healon5, DisCoVisc was retained better in the chamber and was easier to remove. These features of DisCoVisc should be highly advantageous when considering covering the entire cataract surgery procedure with a single OVD.     

Scheimpflug photography study of ophthalmic viscosurgical devices during simulated cataract surgery

PURPOSE: To evaluate by Scheimpflug photography the capacity of several commercially available ophthalmic viscosurgical devices (OVDs) to remain in the anterior chamber and maintain anterior chamber depth (ACD) during simulated cataract surgery in porcine cadaver eyes. SETTING: Department of Preclinical Ophthalmology, Pharmacia & Upjohn AB, Uppsala, Sweden. METHODS: Eighty eyes from newly slaughtered pigs were used. They were distributed equally among 8 OVDs: Amvisc Plus (sodium hyaluronate 1.6%), Biolon (sodium hyaluronate 1.0%), Biolon Prime (sodium hyaluronate 1.2%), Healon (sodium hyaluronate 1.0%), Healon GV (sodium hyaluronate 1.4%), Healon5 (sodium hyaluronate 2.3%), Provisc (sodium hyaluronate 1.0%), and Viscoat (sodium hyaluronate 3.0%-chondroitin sulfate 4.0%). Scheimpflug photographs were taken using a Nidek EAS-1000 instrument before surgery (control), after injection of the OVD, after continuous curvilinear capsulorhexis (CCC), and after lens extraction by phacoemulsification. Differences in the ACD with a P value less than 0.05 were considered statistically significant. The retention capacity was visually assessed. RESULTS: Healon5 had a significantly higher capacity to maintain the ACD than the other OVDs after CCC and phacoemulsification. After injection, Healon5, Viscoat, and Biolon Prime showed similar ACD-maintaining capacities. CONCLUSIONS: The capacity of Healon5 to maintain the ACD during cataract surgery, ie, neutralizing the vitreous pressure and stabilizing the anterior segment of the eye, was significantly higher than that of the other OVDs.     

Effect of incisional friction and ophthalmic viscosurgical devices on the heat generation of ultrasound during cataract surgery

PURPOSE: To determine the thermal features of the Legacy (Alcon) and Sovereign (Advanced Medical Optics) phacoemulsification machines in a cadaver eye and with 7 ophthalmic viscosurgical devices (OVDs). SETTING: In situ and in vitro study. METHODS: Temperature without occlusion was recorded at the sleeve placed in the wound of a cadaver eye, and temperature over baseline was determined after 60 seconds. The result was then compared with the results in a previous study that used balanced salt solution (BSS) in artificial chambers. In the second portion of the experiment, with irrigation and aspiration lines occluded, temperature was recorded at the sleeve placed in an artificial chamber filled with sodium hyaluronate 2.3% (Healon5), sodium hyaluronate 1.4% (Healon GV), sodium hyaluronate 1.0% (Healon), sodium hyaluronate 1.6% (Amvisc Plus), sodium hyaluronate 1.0% (Provisc), sodium hyaluronate 3.0%-chondroitin sulfate 4.0% (Viscoat), or hyaluronate 3.0% (Vitrax). Temperature over baseline was also determined after 60 seconds. These results were compared with each set of OVD data and with the results in the prior BSS study. RESULTS: In the eye-bank model, the Legacy machine had a 62% temperature increase from incisional friction and the Sovereign machine had a decrease of 8.6% over results in an artificial anterior chamber. The OVD temperature increases were greater for the Sovereign (P<.001) and followed the same general trend for the Legacy. The least temperature increase was with Amvisc Plus, Healon, and Healon GV; the intermediate increases were with Provisc and Vitrax; and the greatest increases were with Viscoat and Healon5. The OVD findings did not correlate with viscosity or pseudoplasticity. CONCLUSIONS: Incisional friction alone increased heat generation in the Legacy, a stroke-length driven instrument, more than in the Sovereign, a power-driven instrument. Ophthalmic viscosurgical devices are not only a concern due to outflow occlusion but can also add up to 6 times the heat in comparison with BSS. The need to aspirate the OVD before using ultrasound is thus verified.     

Transient vacuolar changes of the crystalline lens in patients using a dispersive ophthalmic viscosurgical device

AIM: To report the clinical prognosis and pathological findings of accidental lens vacuolar changes in eyes with intraoperative exposure to a dispersive ophthalmic viscosurgical device (OVD). METHODS: Two patients who developed transient lens vacuolar changes during uneventful persistent pupillary membrane (PPM) removal surgery were presented and followed up. This event was speculated to be associated with an intraoperative dispersive OVD DisCoVisc (hyaluronic acid 1.6%-chondroitin sulfate 4.0%) exposure. Then, to provide the pathological basis for our speculation, another four cataract patients were randomly exposed to different OVDs, and their anterior lens capsules were investigated with transmission electron microscopy (TEM). RESULTS: After months, the subcapsular vacuoles in both PPM cases were gradually disappeared without visual deterioration. For the cataract patients, similar lens changes were observed intraoperatively in those exposed to a dispersive DisCoVisc but not a cohesive OVD IVIZ (sodium hyaluronate gel 1.0%). In addition, marked ultrastructural changes, including chromatin condensation, extensive cytoplasmic vacuoles, and obvious intercellular space between lens epithelial cells in the anterior lens capsules of all eyes exposed to DisCoVisc, were observed by TEM. CONCLUSION: The lens vacuolar changes may be associated with a dispersive OVD exposure. Therefore, it is not preferable to use dispersive OVDs in patients with transparent lenses or without the intention of lens extraction. In addition, close follow-ups instead of immediate lens extraction are recommended for the occurrence of similar lens lesions.     

Intraocular pressure after bilateral cataract surgery using Healon, Healon5, and Healon GV

PURPOSE: To determine whether there is a difference in frequency or severity of postoperative intraocular pressure (IOP) spikes after bilateral phacoemulsification with complete ophthalmic viscosurgical device (OVD) removal when Healon5 (sodium hyaluronate 2.3%), Healon (sodium hyaluronate 1%), or Healon GV (sodium hyaluronate 1.4%) is used. SETTING: York Finch Eye Associates and Humber River Regional Hospital, Toronto, Ontario, Canada. METHODS: Bilateral cataract surgery was performed in 99 patients; 50 were randomly assigned to receive Healon5 in 1 eye and Healon GV in the fellow eye and 49, Healon in 1 eye and Healon GV in the fellow eye. The IOP was measured preoperatively as well as 5 and 24 hours and 7 days postoperatively. The mean IOP and standard deviation at each time interval were calculated for each OVD. The results were compared among the OVDs using Student t tests for each time at which IOP was assessed. RESULTS: There were no significant differences in postoperative IOP spikes among the Healon5, Healon, and Healon GV groups; however, patients receiving lower viscosity OVDs had a lower mean IOP at 24 hours. All groups had increased IOP at 5 and 24 hours and reduced IOP at 7 days. CONCLUSIONS: Within a family of molecularly similar OVDs, lower viscosity OVDs appear to cause slightly lower mean elevations in IOP in normal patients at 24 hours. However, if the OVD is removed, postoperative IOP spikes above 21 mm Hg appear related more to patient factors (eg, predisposition in glaucoma patients) and surgically induced trauma than to the specific long-chain non-cross-linked hyaluronan OVD used.     

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.     

Removal times for a dispersive and a cohesive ophthalmic viscosurgical device correlated with intraocular lens material

PURPOSE: To investigate the removal times of ophthalmic viscosurgical devices (OVDs) with different intraocular lens (IOL) designs and materials. SETTING: Center for Research on Ocular Therapeutics and Biodevices, Department of Ophthalmology, Storm Eye Institute, Medical University of South Carolina, Charleston, South Carolina, USA, and Heidelberg IOL & Refractive Surgery Research Group, Department of Ophthalmology, Ruprecht-Karls-University of Heidelberg, Heidelberg, Germany. METHODS: In a standardized laboratory setup, the Miyake-Apple posterior view video technique was used to evaluate OVD removal from capsular bags in human autopsy eyes implanted with poly(methyl methacrylate) (PMMA), silicone, and acrylic IOLs. The cohesive OVD ProVisc (sodium hyaluronate 1.0%) and the dispersive OVD Viscoat (sodium hyaluronate 3.0% and chondroitin sulfate 4.0%) were stained with fluorescein for better visualization. The open-sky preparation and an Alcon Series 20000 Legacy phaco machine with a flow rate of 25 mL/min and a vacuum setting of +500 mm Hg (maximum irrigation/aspiration) were used. The time needed for complete removal of the cohesive and dispersive OVDs with each IOL type was measured and analyzed statistically. RESULTS: The mean removal times for both OVDs were as follows: Alcon MZ60BD PMMA IOL-25.0 seconds +/- 3.7 (SD) (Viscoat), 15.9 +/- 6.9 seconds (ProVisc); Alcon AcrySof MA60BM IOL-35.5 +/- 10.0 seconds (Viscoat), 25.6 +/- 4.7 seconds (ProVisc); Chiron/Bausch & Lomb C1043 silicone IOL-46.5 +/- 10.5 seconds (Viscoat), 17.3 +/- 2.1 seconds (ProVisc); AMO SI-30 silicone IOL-33.5 +/- 3.1 seconds (Viscoat), 15.3 +/- 6.3 seconds (ProVisc); and Pharmacia 912 silicone IOL-18.3 +/- 5.8 seconds (Viscoat), 19.8 +/- 4.3 seconds (ProVisc). CONCLUSIONS: Differences in OVD removal times were detected. The removal time for the cohesive OVD correlated with the IOL material. Overall, the time needed for complete removal was significantly longer for the dispersive OVD than for the cohesive OVD.     

Two-compartment technique to remove ophthalmic viscosurgical devices

To avoid postoperative intraocular pressure peaks, complete removal of all ophthalmic viscosurgical devices (OVDs) used during cataract surgery is important. Depending on the kind of OVD used, different removal techniques have been applied. We describe a technique that was used in more than 250 eyes for safe removal of OVDs, especially viscoadaptive OVDs such as sodium hyaluronate 2.3% (Healon5). It takes advantage of the viscoadaptive properties of Healon5 and was named the 2-compartment technique.     

The Clinical Study of Healon 5 in Phacoemulsification and IOL Implantation

Purpose: To compare a new ophthalmic viscoelastic device (OVD) Healon 5 with two other kinds of OVDs commonly used in China during phacoemulsification and intraocular lens (IOL) implantation in terms of removal time, intraocular pressure, corneal and anterior chamber response.Methods: This prospective randomized study, in which patients and observers are masked, comprises niety eyes. They were randomly divided into 3 groups with different OVDs. Healon 5 (sodium hyaluronate 5 000 2.3%) was compared with Healon GV (sodium hyaluronate 7 000 1.4%) and Iviz (sodium hyaluronate 1.0%) . The surgeries were performed with temporal corneal incision, phacoemulsification in situ and foldable lens intracapsular implantation. The characteristic and the removal time of the viscoelastic material as well as the postoperative IOP, corneal reaction and anterior chamber reactions of the eyes were observed preoperatively and 24 hrs postoperatively. Exclusion criteria were glaucoma, a preoperative dilated pupil diameter small     

Clinical comparison of Healon5 and Healon in phacoemulsification and intraocular lens implantation; Randomized multicenter study

PURPOSE: To compare the overall clinical performance during phacoemulsification and intraocular lens (IOL) implantation, the effect on intraocular pressure (IOP), and the effect on corneal endothelium of Healon5 (sodium hyaluronate 2.3%) and Healon (sodium hyaluronate 1.0%) ophthalmic viscosurgical devices (OVDs). SETTING: Multicenter study. METHODS: In this randomized prospective clinical study, the performance of Healon5 (viscoadaptive; dispersive and cohesive) and Healon (cohesive) during cataract surgery was evaluated in 157 patients, 79 with Healon5 and 78 with Healon. Surgeons evaluated the following on a 5-point scale: retention during phacoemulsification (primary endpoint), ease of injection, anterior chamber maintenance during continuous curvilinear capsulorhexis (CCC), facilitation of IOL implantation, and ease of removal from the eye. Masked examiners other than the surgeon performed the following measurements: IOP preoperatively and 5 and 24 hours, 7 days, and 3 months postoperatively; corneal thickness before and 24 hours, 7 days, and 3 months postoperatively; and corneal endothelial cell count preoperatively and 3 months postoperatively. RESULTS: Intraocular retention during phacoemulsification was assessed as good or very good in 77% in the Healon5 group and 8% in the Healon group; the difference was statistically significant (P<.0001, Wilcoxon rank sum test). The Healon5 group had significantly better scores for anterior chamber maintenance during CCC (P<.0001) and facilitation of IOL implantation (P =.032), and the Healon group had significantly better scores for ease of injection (P<.0001) and ease of removal (P<.0001). There were no statistically significant between-group differences in IOP, corneal endothelial cell count, or corneal thickness. CONCLUSIONS: Surgeons rated Healon5 better than Healon in retention during phacoemulsification, anterior chamber maintenance during CCC, and facilitation of IOL implantation. They assessed Healon as easier to inject and remove. There was no difference in safety-related parameters between the 2 OVDs. These findings indicate that Healon5 is effective in cataract surgery.     

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.     

Influence of viscoelastic substances used in cataract surgery on corneal metabolism and endothelial morphology: comparison of Healon and Viscoat.

PURPOSE: To evaluate the influence of cohesive and dispersive ophthalmic viscosurgical devices (OVDs) on endothelial morphology and corneal metabolism during cataract surgery. SETTING: Department of Ophthalmology, University of Vienna Medical School, Vienna, Austria. METHODS: In this prospective randomized blind study, 50 eyes of 43 patients were randomized into 2 groups before surgery. Phacoemulsification with implantation of a posterior chamber intraocular lens was performed in all patients. In half the patients, sodium hyaluronate 1% (Healon) was used as the OVD and in the other half, sodium hyaluronate 3%-chondroitin sulfate 4% (Viscoat). Corneal metabolism was evaluated by fluorophotometric measurement of corneal autofluorescence. The corneal fluorescence values were corrected for interference by fluorescence of the ocular lens. Specular microscopy (Noncon Robo SP800, Canon) was used to evaluate the endothelial cell density, coefficient of variation, and percentage of hexagonal cells. Examinations were performed preoperatively and 3 days, 1 and 4 weeks, and 3 months postoperatively. RESULTS: There were no significant changes between preoperative and postoperative endothelial cell density measurements in either group (P =.1717). The percentage of hexagonal cells was similar (P =.3489); however, there was a slightly increasing tendency toward polymorphism in both groups. Corneal autofluorescence decreased 3 days after surgery, increased after 1 week, and decreased again subsequently in both groups. There was no significant difference in the influence on corneal metabolism between the 2 OVDs (P =.9899). CONCLUSIONS: There was no significant difference between Healon and Viscoat. Thus, this study did not confirm an advantage of either for endothelial protection of healthy corneas.     

Oxidative tissue damage after phacoemulsification: influence of ophthalmic viscosurgical devices

PURPOSE: To quantify the oxidative tissue damage after phacoemulsification, correlate the damage to the energy applied, and investigate the influence of ophthalmic viscosurgical devices (OVDs). SETTING: Department of Ophthalmology, University of Mainz, Mainz, Germany. METHODS: The study comprised 130 eyes operated on by 1 surgeon using the same phacoemulsification machine. Some eyes received an OVD before phacoemulsification and some did not. Energy values were expressed as phaco time; that is, ultrasound (US) time (seconds) after conversion to 100% phaco power. Patients were grouped as follows: Group 1, phaco time less than 20 seconds and no OVD; Group 2, phaco time 20 to 40 seconds and no OVD; Group 3, phaco time more than 40 seconds and no OVD; Group 4, phaco time 20 to 40 seconds and hydroxypropyl methylcellulose 2% (HPMC); Group 5, phaco time 20 to 40 seconds and sodium hyaluronate 1%. Aqueous humor from pseudophakic eyes served as a control. At the end of surgery, anterior chamber fluid was analyzed for lipid peroxides using the thiobarbituric acid method. RESULTS: Lipid peroxides were detected in all groups. The values were significantly higher in Group 2 than in Group 1 (P<.01) and in Group 3 than in Groups 1 and 2 (P<.01). The differences in lipid peroxide values between all phaco groups and the control group were statistically significant. Sodium hyaluronate 1% and HPMC 2% produced significantly lower lipid peroxide values than in the respective phaco groups that did not receive an OVD (both P<.01). CONCLUSIONS: Oxidative tissue damage occurred during phacoemulsification. The damage, which correlated with the US energy applied, can be reduced by the use of OVDs.     

Removal times and techniques of a viscoadaptive ophthalmic viscosurgical device

PURPOSE: To analyze removal techniques for Healon5 (sodium hyaluronate 2.3%). SETTING: Center for Research on Ocular Therapeutics and Biodevices, Charleston, South Carolina, USA, and Department of Ophthalmology, Ruprecht-Karls-University, Heidelberg, Germany. METHODS: In a standardized laboratory setup, the Miyake-Apple posterior view video technique in human autopsy eyes was used to evaluate removal of an ophthalmic viscosurgical device (OVD) from capsular bags implanted with poly(methyl methacrylate), silicone, and acrylic intraocular lenses (IOLs). Healon5 was stained with fluorescein for better visualization. Open-sky preparation and an Alcon Legacy Series 20000 phaco machine with a flow rate of 25 mL/minute and a vacuum setting of +500 mm Hg (maximum irrigation/aspiration [I/A]) were used. With Technique 1, the I/A tip was placed on the center of the IOL and maximum aspiration was applied. With Technique 2 (modified rock 'n roll technique), the I/A tip was moved in quick circular movements on top of the IOL to break the OVD chains and facilitate aspiration. RESULTS: With Technique 1, the mean removal time was 59.0 seconds +/- 23.1 (SD) and with Technique 2, 23.6 +/- 10.3 seconds (P =.004). The removal time of Healon5 correlated with the IOL material. With Technique 2, removal was fastest with silicone IOLs (13.5 +/- 2.1 seconds) followed by PMMA IOLs (17.5 +/- 2.1 seconds). With acrylic IOLs, remnants of the OVD trapped behind the IOL optic resulted in a longer removal time of 34.1 +/- 1.2 seconds. CONCLUSIONS: Healon5 was completely removed from the capsular bag with the modified rock 'n roll technique. With acrylic IOLs, remnants can be trapped behind the optic and may be overlooked with an unstained OVD. Aspiration behind the optic is recommended with this IOL type.     

New classification of ophthalmic viscosurgical devices--2005

PURPOSE: To revise the generally accepted classification of ophthalmic viscosurgical devices (OVDs) to include cohesion data and the new class of viscous dispersive OVDs. SETTING: York Finch Eye Associates, Toronto, Ontario, Canada, and Alcon Research Limited, Fort Worth, Texas, USA. METHODS: Pseudoplasticity and cohesion-dispersion (CDI) data of DisCoVisc (hyaluronic acid 1.6%-chondroitin sulfate 4%), a new viscous dispersive OVD, were determined and compared with existing OVDs. The existing classification of OVDs was unable to accommodate its properties, so the classification was modified to include a new class and other potential new classes which currently remain unoccupied. RESULTS: Current OVD classification, although based on the clinically significant rheologic parameters of zero-shear viscosity and cohesion, only uses zero-shear viscosity because of the high correlation of these 2 parameters in existing OVDs. The appearance of DisCoVisc forces modification of the existing scheme because it does not fit into a preexisting category. The new proposed broadened classification is changed from a 1-dimensional list into a 2-dimensional table and considers CDI independently from viscosity for all OVDs. Expansion of the classification of OVDs in this manner predicts further possible new innovative OVDs for surgical use. CONCLUSION: The surgical behavior of OVDs can be predicted by their position in a classification of OVDs based upon zero-shear viscosity and cohesion.     

Transient corneal edema after phacoemulsification: comparison of 3 viscoelastic regimens

PURPOSE: To evaluate the effect of different viscoelastic substances on the grade and time course of postoperative corneal edema. SETTING: Department of Clinical Sciences/Ophthalmology, Ume? University Hospital, Ume?, Sweden. METHODS: This study comprised 62 patients with otherwise healthy eyes who had routine phacoemulsification and intraocular lens (IOL) implantation. Patients were divided into 3 groups. Group 1 was given Healon GV (sodium hyaluronate 1.4%) at phacoemulsification and IOL implantation. Group 2 was given Viscoat (sodium hyaluronate 3.0%-chondroitin sulfate 4.0%) at phacoemulsification and Healon GV at IOL implantation. Group 3 was given Viscoat at phacoemulsification and Provisc (sodium hyaluronate 1.0%) at lens implantation. The central corneal thickness was measured with ultrasonic pachymetry before surgery and 5 and 24 hours, 1 week, and 1 month after surgery. RESULTS: The mean increase in corneal thickness was significantly greater in Group 1 than in the other 2 groups 5 and 24 hours and 1 week after surgery. CONCLUSIONS: The transient postoperative increase in central corneal thickness was greater in patients receiving Healon GV during phacoemulsification than in patients receiving Viscoat. The use of Provisc or Healon GV for IOL implantation did not affect the postoperative corneal thickness when Viscoat was used for phacoemulsification. The time course of the edema may be explained by a difference between the 2 agents in endothelial protection from ultrasonic, mechanical, or irrigation trauma.     

Effects of topical dorzolamide on IOP after phacoemulsification with different types of ophthalmic viscosurgical devices

PURPOSE: To evaluate the effect of topical dorzolamide on postoperative intraocular pressure (IOP) after routine phacoemulsification surgery with different type of ophthalmic viscosurgical device (OVD). METHODS: Patients who were scheduled for phacoemulsification with intraocular lens (IOL) implantation were evenly divided into four groups. Group I (83 eyes) received one drop of topical dorzolamide immediately after surgery and 1.4% NaHa (BD Visc) was used as a cohesive OVD during IOL implantation. Group II (83 eyes) did not receive any topical antiglaucoma medication after operation and 1.4% NaHa was used as a cohesive OVD. Group III (83 eyes) received topical dorzolamide and 1% NaHa (Healon) was used, and Group IV (83 eyes) did not receive any topical and 1% NaHa was used in operation. Mean postoperative IOPs were compared between groups. RESULTS: Eyes with 1.4% NaHa usage (18.2+/-9.2 mmHg) had higher mean postoperative IOPs than eyes with 1% NaHa usage (15.5+/-5.3 mmHg) (p=0.002). Mean postoperative IOPs were lower in eyes with dorzolamide application (15.6+/-7.2 mmHg) than in eyes without any medication (18.1+/-8.5 mmHg) both in eyes with 1.4% NaHa and 1% NaHa usage (p=0.003). Dorzolamide application caused an average 2.5 mm decrease in mean postoperative IOPs in both groups. CONCLUSIONS: Effects of OVDs on IOP rises after phacoemulsification surgery are closely related to their molecular structure. Increase in viscosity rendered higher postoperative IOP increments. However, topical dorzolamide application effectively reduced postoperative IOP increments in eyes with both Healon and BD Visc use.     

Completion rate of continuous curvilinear capsulorhexis in pediatric cataract surgery using different viscoelastic materials

PURPOSE: To determine whether viscoelastic materials with a higher viscosity allow better control of the lens capsule, reducing the rate of incomplete continuous curvilinear capsulorhexis (CCC) during pediatric cataract surgery. SETTING: Department of Ophthalmology, University of California, San Francisco Medical Center, San Francisco, California, USA. METHODS: This retrospective study comprised 25 eyes of 18 children who had cataract surgery by 1 surgeon. The type of viscoelastic agent used for the CCC portion of the surgery was obtained from surgical dictations and nursing charts and information on complications during the CCC, from surgical dictations. The patient's age, type of cataract, and intraocular lens placement were also obtained. RESULTS: A CCC was successfully performed in 7 of 15 eyes (46.7%, mean age 7.6 years) using cohesive Healon (sodium hyaluronate 1%) or dispersive Viscoat (sodium hyaluronate 3%-chondroitin sulfate 4%) viscoelastic material and in 9 of 10 eyes (90%, mean age 6.4 years) using the high-viscosity viscoadaptive agent Healon 5 (sodium hyaluronate 2.3%) (chi square = 4.8900; P<.05). The unsuccessful CCCs in the Healon/Viscoat group were in 2 eyes with mature cataract, 1 eye with posterior polar cataract, 1 eye with posterior subcapsular cataract, and 4 eyes with lamellar cataract. The unsuccessful CCC in the Healon5 group was in 1 eye with mature cataract. CONCLUSION: The superviscous properties of Healon5 under low turbulence conditions appear to lead to a higher CCC completion rate in children.