In vitro behavior of ophthalmic viscosurgical devices during phacoemulsification

Transient anterior subcapsular vacuolar lens opacities after Tanito microhook trabeculotomy: report of six cases

OBJECTIVE

To present six cases exhibiting transient anterior subcapsular vacuolar lens opacities following early postoperative Tanito microhook trabeculotomy (TMH) performed by the same surgeon.

METHODS

Six patients who underwent lens-sparing TMH at Meizankai Shimizu Eye Clinic from November 2021 to May 2023, and developed anterior subcapsular vacuolar lens opacities postoperatively were reviewed. Detailed records of surgeries, follow-up findings were collected and reported.

RESULTS

In all six cases, anterior vacuolar subcapsular lens opacities were observed on the day after surgery, gradually decreasing without affecting visual acuity or contrast sensitivity. In all cases, without any specific interventions, the opacities disappeared by 21 months postoperatively.

CONCLUSION

Anterior subcapsular cataracts, characterized by a vacuolar appearance and transient existence, should be recognized as an early complication of ab interno glaucoma surgery, possibly linked to use of distributed ophthalmic viscosurgical devices and excessive anterior chamber irrigation leading to traumatic cataracts on the lens surface.

Retention time of different ophthalmic viscosurgical devices during phacoemulsification in rabbit ocular model: A comparative analysis

BACKGROUND

To compare retention times of various ophthalmic viscosurgical devices (OVDs) and soft-shell combinations.

METHODS

Experimental study. Eighteen rabbit eyes were divided into six groups of three eyes, based on OVDs tested. A: Endocoat, B: HealonPro, C: Viscoat, D: Provisc, E: Endocoat and HealonPro and F: Viscoat and Provisc. OVDs were stained with 10% fluorescein dye before being injected into the anterior chamber. Phacoemulsification, using fixed parameters, was performed. If OVD persisted after 60 s, a standardised irrigation and aspiration technique replaced phacoemulsification. The time until central and complete clearance of the OVD were video-recorded and measured.

RESULTS

Mean central retention times (CRT) were found to be: HealonPro-5.33 ± 2.56 s, Provisc-3.33 ± 1.11 s, Endocoat-75.0 ± 3.26 s, Viscoat-62.33 ± 5.19 s, combining HealonPro with Endocoat-22.67 ± 4.75 s and Provisc with Viscoat-11.0 ± 0.82 s. The mean total retention time (TRT) was: Endocoat-80.0 ± 8.17 s, Viscoat-81.67 ± 2.09 s, HealonPro with Endocoat-81.33 ± 3.35 s, and Provisc with Viscoat-71.0 ± 2.94 s. For HealonPro and Provisc, CRT and TRT remained identical across all trials.

CONCLUSIONS

Retention times varied, with cohesive OVDs exhibiting shorter durations than dispersive OVDs. Among dispersive OVDs, TRTs were comparable; however, Endocoat displayed an extended CRT. In soft shell trials, the combination of HealonPro and Endocoat exhibited prolonged CRT and TRT, suggesting enhanced corneal protection.

Comparison of the Residual Amount of an Ophthalmic Viscosurgical Device Among Different Types of Intraocular Lens Implants in vitro

Purpose

Although ophthalmic viscosurgical devices are quite important for safe cataract surgery, currently, postoperative residual ophthalmic viscosurgical devices can cause various complications. Previously, we developed a method to visualize residual ophthalmic viscosurgical devices after irrigation/aspiration in vitro and found that the amount of residual ophthalmic viscosurgical device on a single-piece intraocular lens was greater than that on a three-piece intraocular lens. In the present study, we compared the amounts of residual ophthalmic viscosurgical device among various foldable intraocular lenses to investigate the factors that determine the quantity of residual ophthalmic viscosurgical device.

Patients and Methods

Simulated cataract surgery was performed in pig eyes using an ophthalmic viscosurgical device labeled with fluorescent silica particles. After the simulated surgery procedure, the fluorescent silica attached to the intraocular lens was observed and quantified by inductively coupled plasma-atomic emission spectrometry after intraocular lens removal. The amount of residual ophthalmic viscosurgical device was compared among five representative single-piece intraocular lenses and one three-piece intraocular lens.

Results

The distribution and amount of the residual ophthalmic viscosurgical device differed for each intraocular lens. The amount of silicon in the lens capsule differed among the intraocular lens types.

Conclusion

The postoperative residual tendency of ophthalmic viscosurgical devices differed among various single-piece intraocular lenses. The behavior of the intraocular lenses within the capsule affected the residual tendency. The removal of ophthalmic viscosurgical device in the lens capsule should be tailored for each intraocular lens to improve efficiency.

Safety and effectiveness comparison of a new cohesive ophthalmic viscosurgical device

PURPOSE

To evaluate the safety and effectiveness of a new cohesive ophthalmic viscosurgical device (OVD) (StableVisc) compared with a marketed cohesive OVD (ProVisc) in patients undergoing cataract surgery.

SETTING

22 sites in the United States.

DESIGN

Prospective multicenter controlled double-masked and randomized 1:1 (StableVisc:ProVisc; stratified by site, age group, and cataract severity).

METHODS

Adults (≥45 years) with age-related noncomplicated cataract considered amenable to treatment with standard phacoemulsification cataract extraction and intraocular lens implantation were included. Patients were randomized to receive either StableVisc or ProVisc during standard cataract surgery. Postoperative visits occurred at 6 hours, 24 hours, 7 days, 1 month, and 3 months. The primary effectiveness outcome was the change in endothelial cell density (ECD) from baseline to 3 months. The primary safety endpoint was the proportion of patients who experienced at least 1 intraocular pressure (IOP) measurement ≥30 mm Hg at any follow-up visit. Noninferiority between the devices was tested. Inflammation and adverse events were evaluated.

RESULTS

390 patients were randomized; 187 patients with StableVisc and 193 patients with ProVisc completed the study. StableVisc was noninferior to ProVisc in mean ECD loss from baseline to 3 months (17.5% and 16.9%, respectively). StableVisc was noninferior to ProVisc in the proportion of patients with postoperative IOP ≥30 mm Hg at any follow-up visit (5.2% and 8.2%, respectively).

CONCLUSIONS

The StableVisc cohesive OVD, which provides both mechanical and chemical protection, was safe and effective when used in cataract surgery and provides surgeons with a new cohesive OVD.

Temperature Change of Ophthalmic Viscosurgical Devices in a Bi-Chamber Set-Up at a Flow of 0 and 20mL/min

Purpose

To understand the role of ophthalmic viscosurgical devices (OVDs) in corneal incision contracture (CIC). Specifically, the aim was to evaluate with the tip of the phacoemulsification needle free of OVD, how various OVDs near the tip and sleeve may transmit thermal energy to the incision site.

Methods

A small chamber was filled with balanced saline solution (BSS), and a thin membrane was placed on the surface. OVD was placed atop the membrane. A temperature probe was placed in the OVD, while the handpiece pierced the membrane. The experiment was run both with and without flow and vacuum. Temperature measurements were gathered for each of the OVDs at four separate time points at 0 and 20mL/min flow.

Results

As expected, there was a more pronounced temperature increase in all test groups with no fluid flow. While the temperature increase was not significantly different from BSS for any of the OVDs tested at either 0 or 20mL/min, Viscoat showed the most variable results at both flow settings.

Conclusion

As long as the phaco tip is not in OVD, residual OVD near the incision is not exothermic and so not an additional risk for CIC.

The safety and effectiveness of a new ophthalmic viscosurgical device-a randomized, controlled study

ClearVisc was significantly noninferior to Viscoat in the mean percentage of ECD loss from baseline to 3 months and proportion of patients with postoperative IOP ≥30 mm Hg at any follow-up.

To evaluate the safety and effectiveness of a new dispersive ophthalmic viscosurgical device (OVD) (ClearVisc) compared with an approved dispersive OVD (Viscoat) when used in cataract surgery.

Ophthalmic Viscosurgical Devices (OVDs) in Challenging Cases: a Review

Ophthalmic viscoelastic devices (OVDs) are currently used in cataract surgery and have significantly improved the safety and effectiveness of this surgical procedure. OVDs are classified according to the zero-shear viscosity and the cohesion-dispersion index in cohesive, dispersive, and viscoadaptives. OVDs create and maintain anterior chamber depth and visibility, protecting the corneal endothelium and other intraocular tissues during surgery. The selection of the most adequate OVD is especially relevant when performing cataract surgery in challenging cases, such as in hard, mature cataracts, flat anterior chamber, pseudoexfoliation syndrome, intraoperative floppy iris syndrome, or glaucoma surgery. In such cases, OVD is crucial for facilitating the surgical procedure and the associated minimal complication rate. The use of a combination of OVDs (soft-shell technique and modifications), the use of blue-colored OVDs, and the combination of sodium hyaluronate with lidocaine have also been described as useful tools in some of these challenging cases.

Advances in Understanding the Mechanism of Ophthalmic Viscosurgical Device Retention in the Anterior Chamber or on the Corneal Surface during Ocular Surgery

Retention durability, especially in the eye, is one of the most important properties of ophthalmic viscosurgical devices (OVDs) during ocular surgery. However, the information on the physical properties of OVDs is insufficient to explain their retention durability. The purpose of this study is to clarify the mechanism of OVD retention to improve understanding of the behavior of OVDs during ocular surgery. To elucidate the mechanism of OVD retention, we have developed a new test method for measuring repulsive force. As a result, the maximum repulsive force of OVDs was positively and well correlated with the retention durability of investigated OVDs. Consequently, we demonstrated that the repulsive force could be used as an index of retention durability on the ocular surface and in the eye. We directly compared the intraocular retention durability of three OVDs (Shellgan, Viscoat, and Opegan-Hi) in ex vivo porcine eyes. Opegan-Hi was immediately removed from the anterior chamber, but Shellgan and Viscoat remained largely in the anterior chamber as determined by fluorescence imaging. These results showed that the intraocular retention behavior of OVDs was similar to their ocular surface behavior in our previous report, suggesting that retention durability is dependent on the OVD itself. The retention durability of Shellgan seemed to be higher than that of Viscoat, and the maximum repulsive force of Shellgan was 1.35-fold higher than that of Viscoat. Therefore, the repulsive force might be a useful index for assessing the difference in the retention durability between OVDs such as Shellgan and Viscoat.

A primer on ocular viscosurgical devices

PURPOSE

To provide pharmacists with an overview of ocular viscosurgical devices (OVDs) and a comprehensive resource describing characteristics of commercially available agents.

SUMMARY

OVDs are substances that are injected into the eye during ophthalmic procedures, such as cataract surgery, to reduce injury to the endothelium that may result from surgical manipulation. Currently available OVDs are composed of one or more of the following active ingredients: sodium hyaluronate, sodium chondroitin sulfate, and hydroxypropylmethylcellulose. Rheologic properties of OVDs, such as viscosity, elasticity, pseudoplasticity, and cohesion, affect the products' function and performance. Based on rheologic properties, OVDs can be generally classified as cohesive or dispersive. Given each products' unique characteristics, OVDs are not interchangeable. An understanding of OVD characteristics and role in practice allows for improved product selection, which varies based on patient characteristics and procedure. Availability of OVD information and literature is generally lacking since OVDs are regulated by the US Food and Drug Administration (FDA) as medical devices. This primer includes an overview of relevant ophthalmic surgical practices and the landscape of comparative efficacy and safety literature to assist in formulary decision-making. This review also provides a comprehensive guide to commercially available OVDs and a discussion on practical considerations for the pharmacist.

CONCLUSION

Pharmacists may be tasked with handling OVDs in institutional settings. Knowledge about OVD rheologic properties, product characteristics, role in practice, and available literature is necessary for managing formularies and ensuring optimal product selection.

Achieving successful capsulorhexis in intumescent white mature cataracts to prevent Argentinian flag sign - A new multifaceted approach to meet the challenge

Purpose:

To present a case series of intumescent white cataract cases managed by a new surgical technique to attain a single stage Continuous Curvilinear Capsulorhexis (CCC).

Methods:

The series included 60 eyes of 60 patients with white cataract which underwent preoperative anterior chamber depth, lens thickness and ultrasonographic A-scan for intralenticular spikes. A partial size main port (~1.8mm) is created as the first entry into the anterior chamber (AC). A 30-gauge needle of insulin syringe entered through a limbal stab incision is used to decompress the anterior and posterior intralenticular compartments. Following which a standard size, one stage capsulorhexis was performed in a trypan blue stained capsule using microcapsulorhexis forceps entered through the partial sized trapezoidal main port. The main port was secondarily enlarged for phacoemulsification.

Results:

Based on the intraoperative findings, 43 eyes were categorized as Intumescent type-1 cataracts i.e., with presence of actual liquefied cortex aspirated using 30-gauge needle and 17 eyes as Intumescent type-2 cataracts, i.e., presence of swollen lens without any obvious liquefied cortex. Standard size, circular and centred CCC was achieved in 100% of the cases and no Argentinean flag sign was noted. Surgeon perceived raised intralenticular pressure in 41% of the cases in type-1 subset and 61% cases in type-2 subset (P-0.06). Posterior capsular plaque was observed in 22% of the cases, adherent cortex in 25% and anterior capsular plaque in 5% of the cases. At 6weeks follow up 92% patients had best corrected visual acuity of 20/40 or better.

Conclusion:

A multi-layered approach can help in attaining successful CCC in cases of white mature cataract with high intralenticular pressure.

Changing trends in penetrating keratoplasty indications at a tertiary eye care center in Budapest, Hungary between 2006 and 2017

AIM

To analyze the changing trends in penetrating keratoplasty (PKP) indications.

METHODS

This retrospective study included all patients with PKP between 2006 and 2017. Patients were classified using histological diagnoses. Our groups were as the following: pseudophakic or aphakic bullous keratopathy, regraft, acute necrotizing and ulcerative keratitis, keratoconus, Fuchs' dystrophy, corneal dystrophy other than Fuchs', corneal scar, other diagnoses and failed endothelial keratoplasty graft. Additionally, two different time-periods (2006-2012 and 2013-2017) were analysed.

RESULTS

Totally 1721 histological analyses of 1214 patients were available for review. The diagnoses were pseudophakic or aphakic bullous keratopathy in 487 (28.3%), regraft in 443 (25.7%), acute necrotizing and ulcerative keratitis in 313 (18.2%), corneal scar in 153 (8.9%), keratoconus in 140 (8.1%). Fuchs' dystrophy in 61 (3.5%), corneal dystrophy other than Fuchs' in 46 (2.7%), other diagnoses in 44 (2.6%) and failed endothelial keratoplasty graft in 34 (2.0%) cases. From the first to the second analysed time-period, incidence of acute necrotizing and ulcerative keratitis, corneal scar, Fuchs' dystrophy increased (P≤0.032 for all) and incidence of keratoconus significantly decreased (P=0.015).

CONCLUSION

Pseudophakic or aphakic bullous keratopathy is the leading indication for PKP, followed by regraft and acute necrotizing and ulcerative keratitis.

Quantitative Assessment of Ophthalmic Viscosurgical Devices on Visibility, Spreadability, and Durability as Corneal Wetting Agents for the Wet Shell Technique

Purpose

To evaluate ophthalmic viscosurgical devices (OVDs) as corneal wetting agents for the wet shell technique, a common procedure in Japan to maintain the wettability of corneal surfaces.

Methods

We surveyed Japanese ophthalmologists to determine the current state of the wet shell technique. After developing three ex vivo testing methods, we evaluated the corneal wetting properties of OVDs including 3% hyaluronic acid (HA) solution and OVD products, Opegan, Opelead, Viscoat, Shellgan, Discovisc, and Opegan-Hi.

Results

Overall, 214 ophthalmologists (70%) had performed the wet shell technique, and 91% of ophthalmologists who performed vitreous surgery had performed this technique. Using a questionnaire, we evaluated the performance of OVD as corneal wetting agents as follows: (i) visibility, smoothness of OVD surface; (ii) spreadability, coverage of the cornea; and (iii) retention durability, residual ratio of OVD on the corneal surface. The smoothness and spreadability of Opegan, Opelead, and 3% HA were superior to other OVDs. Adding an appropriate amount of balanced salt solution to the other OVDs improved smoothness and spreadability similar to that of Opelead or 3% HA. Shellgan and Viscoat, combination OVDs consisting of 3% HA and 4% chondroitin sulfate, showed high retention durability, resulting in remaining longer on the cornea compared with other OVDs.

Conclusions

Physical properties of OVDs tested in this study may provide useful information for ophthalmologists to select a suitable OVD when performing the wet shell technique.

Addition Of D-Sorbitol Improves The Usability Of Ophthalmic Viscosurgical Devices

Purpose

To evaluate the effects of D-sorbitol addition on changes in the extrusion force of ophthalmic viscosurgical devices (OVDs).

Methods

OVD formulations; the mixtures of 3% hyaluronic acid (HA) and 4% chondroitin sulfate (CS) containing 0%, 0.5%, or 1.0% D-sorbitol were prepared. Each prefilled syringe of OVD was stored at room temperature for 0, 15, 30, 60, or 120 mins after a small amount of viscoelastic agent was discharged from the needle. The extrusion force values (kgf) of these OVDs when reused after storage were measured with a texture analyzer. Moreover, 10 healthy adults (5 men and 5 women) used a pinch sensor to measure the extrusion force values for the HA/CS combination without D-sorbitol which was stored in the above manner, and used a 4-step scale to score the usability of OVD.

Results

For the HA/CS combination without D-sorbitol, the extrusion force value was increased from its initial value (storage duration, 0 min) as storage duration increased. However, for the HA/CS combination containing 0.5% or 1.0% D-sorbitol, this value remained almost unchanged over time. Likewise, the pinch sensor-determined extrusion force values of HA/CS combination without D-sorbitol increased, depending on storage duration.

Conclusion

The addition of D-sorbitol to viscoelastic agent may suppress the needle clogging that occurs with OVD storage, and may improve the usability of OVDs during surgery.

Quantification of residual ophthalmic viscosurgical device after irrigation/aspiration in experimental cataract surgery in vitro

PURPOSE

To determine the distribution and quantity of ophthalmic viscosurgical device (OVD) retained in the lens capsular bag after irrigation/aspiration (I/A) in experimental cataract surgery.

SETTING

Department of Ophthalmology, Kashiwa Hospital, Jikei University School of Medicine, Japan.

DESIGN

Experimental study.

METHODS

Fifteen freshly enucleated porcine eyes were used. Sodium hyaluronate 1.0% (Healon) was mixed with a fixed concentration of silica nanoparticles encapsulating fluorescein isothiocyanate (labeled OVD), and it was injected separately into the capsular bag and injector cartridge for intraocular lens (IOL) insertion. After a 3-piece IOL (YA-60BBR) or a 1-piece IOL (iSert 255) was implanted within the capsular bag, OVD was removed by thorough I/A. Eyes that were injected with the labeled OVD into the capsular bag without IOL insertion were used as controls. The distribution of residual OVD in the capsular bag was observed under ultraviolet irradiation using Miyake-Apple view. Then, the excised capsular bag was dissolved in hydrogen fluoride, and silica concentration was measured quantitatively by elemental analysis.

RESULTS

The quantity of residual OVD in the capsular bag was 243.1 μg ± 1.3 (SD) in the 3-piece IOL-implanted group, 383.8 ± 11.1 μg in the 1-piece IOL-implanted group, and 99.0 ± 1.3 μg in the control group. In the 1-piece IOL-implanted eyes, OVD in the form of clumps tended to remain near the center of the optic on the posterior side, and the quantity of residual OVD was significantly greater than in 3-piece IOL-implanted eyes (P < .05).

CONCLUSION

The quantity of residual OVD after I/A could be determined indirectly using labeled OVD, and the quantity was significantly greater in 1-piece IOL-implanted eyes than in 3-piece IOL-implanted eyes.

[Evaluation of Rheological Properties of Cohesive Ophthalmic Viscosurgical Devices Composed of Sodium Hyaluronate with High Molecular Weight-2019]

Ophthalmic viscosurgical devices (OVDs), mainly containing sodium hyaluronate (HA), are used in cataract surgeries to protect the cornea endothelium. In this study, the rheological properties of 9 launched products (containing 1% HA) were evaluated. The molecular weights (MWs) of HA estimated based on intrinsic viscosity varied widely, between 1100-2500 kDa, and showed a particular value for each product. Of the 9 products, 6 are classified as cohesive OVDs and their product specifications show the same value for intrinsic viscosity (25-45 dL/g), with high MW HA (>2000 kDa); however, the MW of each HA showed a particular value (2200-2500 kDa) within the range of the product specification. As with the MW of HA, apparent viscosity and dynamic rheological parameters showed particular values for each OVD. The product Opegan-Hi exhibited the highest value of apparent viscosity at low shear rate, and a solid-like behavior among the OVDs. In a questionnaire survey among 198 cataract surgeons, 42% of surgeons had experienced a difference in ability to maintain the depth of anterior chamber during surgery among the different cohesive OVDs used. This suggested that surgeons select OVD properties based on surgical procedure and patient cases. In conclusion, we demonstrated that each OVD has particular rheological properties within the range of the product specification defined by the intrinsic viscosity. The results might provide useful information for surgeons in their selection of OVDs based on their experience.

Rheological and Adhesive Properties to Identify Cohesive and Dispersive Ophthalmic Viscosurgical Devices

The purpose of this study is to evaluate the usefulness of the rheological properties and adhesive force of ophthalmic viscosurgical devices (OVDs) as parameters for understanding and identifying the surgical behavior of cohesive and dispersive OVDs. The apparent viscosity, and the storage and loss moduli (dynamic rheological parameters) of 50% chondroitin sulfate (CS), 3% sodium hyaluronate (HA), Shellgan (the combination of 3% HA and 4% CS), Opegan (1% HA with a low molecular mass) and Opegan-Hi (1% HA with a high molecular mass) were obtained with a rheometer. The adhesive force of each sample was measured by using a texture analyzer. Opegan-Hi showed a solid-like behavior, while 50% CS showed a fluid-like behavior from their apparent viscosity and dynamic rheological parameters. Shellgan, 3% HA, and Opegan exhibited similar rheological properties and intermediate characteristics between Opegan-Hi and 50% CS, although their respective values were slightly different. Among these OVD samples, the adhesive force was higher in the order of 50% CS > Shellgan, 3% HA > Opegan > Opegan-Hi. The adhesive force of dispersive OVDs tended to be higher than that of cohesive OVDs, which correlated well with the removal times of OVDs from the eye that have previously been reported. In conclusion, we demonstrated that cohesive OVDs and dispersive OVDs have particular rheological and adhesive properties that can be applied to identify both types. These parameters obtained in this study provide useful information for a greater understanding and prediction of the behavior of OVDs in the eye during surgery.

A new histological evaluation method to detect residual ophthalmic viscosurgical devices for cataract surgery

Purpose

To establish a new evaluation method to quantify residual ophthalmic viscosurgical device (OVD) volume and corneal endothelium adhesion properties for phacoemulsification surgery.

Methods

We compared the performance of four OVDs (Viscoat®, Healon5®, Healon® and DisCoVisc®) using porcine eyes. First, OVDs were mixed with fluorescent-conjugated dextrans to render them visible under the microscope. A corneal side port was opened, followed by a continuous curvilinear capsulorhexis, and a corneal tunnel incision was made. OVDs were injected, then the lens was removed using one-handed phacoemulsification. After this procedure, the anterior segment of the eye was isolated via an equatorial incision and the tissue was immediately frozen in shimmering liquid nitrogen. Sagittal slices (20 μm) were cut with a Cryostat from limbus to limbus. Every tenth slide was imaged using a fluorescent microscope with a CCD camera. We evaluated the percentage of the corneal endothelium covered by each OVD as the OVD adhesion to corneal endothelium ratio (OAE ratio) and the volume of residual OVD in the anterior chamber.

Results

Viscoat® showed significantly higher endothelium coverage compared with both Healon® and DisCoVisc®. A statistically larger volume of Healon5® remained in the anterior chamber compared with Healon® and DisCoVisc®.

Conclusion

The new evaluation methods used here provide precise quantitative analysis of OAE ratio and residual OVD volume. These results show that Viscoat® and Healon5® have a high potential for coating the corneal endothelium during phacoemulsification and aspiration surgery.

A Novel "Slit Side View" Method to Evaluate Fluid Dynamics during Phacoemulsification

Due to recent technical advances in cataract surgeries, there has been a significant improvement in the safety and surgical outcomes of phacoemulsification. However, the corneal endothelium can be damaged during phacoemulsification by multiple factors. Therefore, we used a slit lamp to analyze the fluid dynamics of ophthalmic viscosurgical devices (OVDs) in the anterior chamber during phacoemulsification. In this experimental study, extracted porcine eyes were injected with OVDs stained with fluorescein through a side port of the eye and then fixed on a slit lamp microscope. After inserting a phaco tip, phacoemulsification simulation was then performed on the iris plane. Subsequent movements of OVDs in the anterior chamber were observed during the procedure by using a slit lamp microscope. Aspiration and removal of cohesive OVDs from the inside of the anterior chamber occurred within a few seconds after the ultrasonic vibration. Aspiration of dispersive OVDs occurred gradually, with some of the OVDs remaining on the side of the anterior chamber side in an irregular shape. This shape enabled the OVD to trap the air, thereby preventing the air from directly touching the corneal endothelium. Viscoadaptive OVDs remained inside the anterior chamber as a lump, with the infusion solution flowing between the corneal endothelium and the OVD, thus leading to the eventual aspiration of the OVD. Viscous dispersive OVDs remained as a lump between the corneal endothelium and the phaco tip. However, once the infusion solution flowed between the cornea and the OVD, the OVD detached from the corneal endothelium, indicating that this type would likely be aspirated and removed. This method, termed the "slit side view," enables viewing of the movement of OVDs during surgery, as well as observation of the fluid dynamics in the anterior chamber.

Application of thermoreversible hydrogel (poloxamer 407) to protect the corneal endothelium during phacoemulsification in porcine and rabbit eyes

PURPOSE

To evaluate the effectiveness of thermoreversible (poloxamer) hydrogels as a substitute for ophthalmic viscosurgical devices (OVDs) during phacoemulsification in porcine and rabbit eyes and compare their endothelial protective effect with that of hyaluronic acid-based OVDs.

SETTING

Department of Ophthalmology, Seoul Metropolitan Government-Seoul National University Boramae Medical Center, Seoul, South Korea.

DESIGN

Experimental study.

METHODS

Fluorescein-stained poloxamer hydrogels (20%, 22%, 24%, and 26% [weight/weight%]) and cohesive (sodium hyaluronate 1.0% [Provisc]) and dispersive (sodium hyaluronate 3.0%-chondroitin sulfate 4.0% [Viscoat]) OVDs were injected into the anterior chamber of porcine eyes incubated at 32°C. In the in vitro study, the retention time was measured in 3 groups of 45 porcine eyes during continuous phacoemulsification. In the in vivo study, the endothelial cell count (ECC) was measured before and 3 days after intermittent phacoemulsification in 12 rabbit eyes randomized to a poloxamer hydrogel or a dispersive OVD group.

RESULTS

The optimum concentration of thermosensitive hydrogel was 26%, at which no gel-to-sol phase transition occurred in the anterior chamber, with a 21°C irrigation solution. In the in vitro study, the mean retention times were 5.53 seconds ± 1.77 (SD), 125.00 ± 29.34 seconds, and 221.53 ± 42.48 seconds in the cohesive OVD, dispersive OVD, and 26% poloxamer hydrogel groups, respectively (P < .001). Throughout the 5-minute intermittent phacoemulsification, the 26% poloxamer hydrogel remained in the anterior chamber as a semisolid gel. In the in vivo study, the mean decrease in ECC was significantly lower in the 26% poloxamer hydrogel group than in the dispersive OVD group (P = .029).

CONCLUSION

Thermoreversible hydrogels might be suitable substitutes for hyaluronic acid-based OVDs for corneal endothelial protection during phacoemulsification.

Mixed polymeric systems: New ophthalmic viscosurgical device created by mixing commercially available devices

PURPOSE

To evaluate the rheological properties of mixtures of different commercially available ophthalmic viscosurgical devices (OVDs) containing sodium hyaluronate and chondroitin sulfate.

SETTING

Eye Clinic, University of Trieste, Trieste, Italy.

DESIGN

Laboratory study.

METHODS

Blends were obtained combining a superviscous cohesive OVD (Healon GV [sodium hyaluronate 1%]) and a medium-viscosity dispersive OVD (Viscoat [sodium hyaluronate 3.0%-chondroitin sulfate 4.0%]). The 2 substances were combined in different ratios, and the rheological characteristics were analyzed to find the optimum proportion. A new viscous dispersive OVD, Discovisc (hyaluronic acid 1.6%-chondroitin sulfate 4.0%) was evaluated for comparison. The storage modulus, loss modulus, crossover point, complex viscosity, shear viscosity, and pseudoplasticity were studied.

RESULTS

The rheological properties of the mixed solution (1:1 and 3:1) showed intermediate characteristics in comparison with the 2 original substances, characterized by a viscosity comparable to that of the superviscous cohesive OVD, but at a higher shear rate (similar to the medium-viscosity dispersive OVD). The new viscous dispersive OVD performed similarly to the medium-viscosity dispersive OVD at low shear rates but was comparable to the superviscous cohesive OVD at high shear rates.

CONCLUSIONS

The mixture of dispersive and cohesive rheological properties in a single OVD might be an advantage during cataract surgery.

Comparison of surgical time and IOP spikes with two ophthalmic viscosurgical devices following Visian STAAR (ICL, V4c model) insertion in the immediate postoperative period

Purpose

To compare the effect of two ocular viscosurgical devices (OVDs) on intraocular pressure (IOP) and surgical time in immediate postoperative period after bilateral implantable collamer lens (using the V4c model) implantation.

Methods

A total of 20 eligible patients were randomized to receive 2% hydroxypropylmethylcellulose (HPMC) in one eye and 1% hyaluronic acid in fellow eye. Time taken for complete removal of OVD and total surgical time were recorded. At the end of surgery, IOP was adjusted between 15 and 20 mmHg in both the eyes.

Results

Mean time for complete OVD evacuation and total surgical time were significantly higher in the HPMC group (P=0.00). Four eyes in the HPMC group had IOP spike, requiring treatment. IOP values with noncontact tonometry at 1, 2, 4, 24, and 48 hours were not statistically significant (P>0.05) for both the groups.

Conclusion

The study concluded that 1% hyaluronic acid significantly reduces total surgical time, and incidence of acute spikes may be lower compared to 2% HPMC when used for implantable collamer lens (V4c model).

Changes in corneal endothelium cell characteristics after cataract surgery with and without use of viscoelastic substances during intraocular lens implantation

PURPOSE

To evaluate whether the use of balanced salt solution (BSS) or an ophthalmic viscoelastic device (OVD) during hydrophilic acrylic intraocular lens (IOL) implantation variously impacts corneal endothelial cell characteristics in eyes undergoing uneventful phacoemulsifications.

METHODS

Prospective nonrandomized observational clinical trial. Patients were assigned either to the BSS plus(®) or to the OVD Z-Celcoat™ group depending on the substance used during IOL implantation. Corneal endothelium cell characteristics were obtained before, 1 week, and 6 weeks after surgery. Intraoperative parameters (eg, surgery time, phacoemulsification energy) were recorded.

RESULTS

Ninety-seven eyes were assigned to the BSS plus and 86 eyes to the Z-Celcoat group. Preoperative corneal endothelium cell density (ECD) and endothelium cell size were 2,506±310 cells/mm(2)/2,433±261 cells/mm(2) and 406±47 µm(2)/416±50 µm(2) (P=0.107/P=0.09). After 1 and 6 weeks, ECD decreased and endothelium cell size increased significantly in both groups (each P<0.001) without significant differences between both groups (each P>0.05). Irrigation-aspiration suction time (30.3±16.6 versus 36.3±14.5 seconds) and overall surgical time (7.2±1.2 versus 8.0±1.4 minutes) were significantly longer in the OVD Z-Celcoat group (each P<0.001). No complications or serious side effects occurred.

CONCLUSION

Implantation of a hydrophilic acrylic IOL under BSS infusion seems to be a useful and faster alternative in experienced hands without generating higher ECD loss rates.

Evaluation of a new method of irrigation and aspiration for removal of ophthalmic viscoelastic device during cataract surgery in a porcine model

BACKGROUND

To determine if a method for irrigation and aspiration (I/A) during cataract surgery provides effective removal of ophthalmic viscoelastic device (OVD).

METHODS

Japanese porcine eyes were used to evaluate I/A performance with Technique 1 (the I/A tip placed on the center of the anterior surface of the IOL), Technique 2 (the I/A tip alternately pressed near the edge of the IOL optic anterior surface on one side and then the other to tilt the IOL back and forth), and Technique 3 (the I/A tip inserted behind the IOL optic, between it and the posterior capsule). Techniques 1 and 2 were compared using the Miyake-Apple posterior view video technique to visualize the flow of irrigation fluid containing triamcinolone acetonide particles behind the IOL. To check the efficacy of OVD removal from behind the IOL for of all three I/A techniques, OVD with fluorescein beads were inserted inside the lens capsule before implantation of the IOL. After each I/A technique, eyes were prepared for Miyake-Apple viewing and pictures of the lens capsule were taken using fluorescent microscopy. Residual fluorescein beads in the capsular bag were analyzed.

RESULTS

Technique 1 resulted in a straight flow of fluid behind the IOL, while Technique 2 resulted in a vortex flow. The average amount of OVD retained inside the capsule after using Technique 2 or 3 was significantly lower than after using Technique 1 (p <0.0001).

CONCLUSIONS

Technique 2 proved to remove more effectively fluorescein bead-labelled OVD under the IOL than Technique 1.

A clinical comparison between DisCoVisc and 2% hydroxypropylmethylcellulose in phacoemulsification: a fellow eye study

OBJECTIVE

This study sought to compare the effects and outcomes of two ophthalmic viscosurgical devices, 1.6% hyaluronic acid/4.0% chondroitin sulfate and 2.0% hydroxypropylmethylcellulose, during phacoemulsification.

METHODS

This prospective, randomized clinical trial comprised 78 eyes (39 patients) that received phacoemulsification performed by the same surgeon using a standardized technique. Patients were randomly assigned to receive either 1.6% hyaluronic acid/4.0% chondroitin sulfate or 2.0% hydroxypropylmethylcellulose on the first eye. The other eye was treated later and received the other viscoelastic agent. Preoperative and postoperative examinations (5, 24 and 48 hours; 7 and 14 days; 3 and 6 months) included measurements of the total volume of the ophthalmic viscosurgical device, ultrasound and washout times to completely remove the ophthalmic viscosurgical device, intraocular pressure, central corneal thickness and best-corrected visual acuity. The corneal endothelial cell count was measured at baseline and at six months postoperatively. ClinicalTrials.gov: NCT01387620.

RESULTS

There were no statistically significant differences between groups in terms of cataract density or ultrasound time. However, it took longer to remove 2.0% hydroxypropylmethylcellulose than 1.6% hyaluronic acid/ 4.0% chondroitin sulfate, and the amount of viscoelastic material used was greater in the 2.0% hydroxypropylmethylcellulose group. In addition, the best-corrected visual acuity was significantly better in the hyaluronic acid/ chondroitin sulfate group, but this preferable outcome was only observed at 24 hours after the operation. There were no statistically significant differences between the two ophthalmic viscosurgical devices regarding the central corneal thickness or intraocular pressure measurements at any point in time. The corneal endothelial cell count was significantly higher in the hyaluronic acid/chondroitin sulfate group.

CONCLUSION

The ophthalmic viscosurgical device consisting of 1.6% hyaluronic acid/4.0% chondroitin sulfate was more efficient during phacoemulsification and was easier to remove after IOL implantation than 2.0% hydroxypropylmethylcellulose. In addition, the corneal endothelial cell count was significantly higher following the use of hyaluronic acid/chondroitin sulfate than with hydroxypropylmethylcellulose, which promoted an improved level of corneal endothelium protection.

Safety, efficacy, and intraoperative characteristics of DisCoVisc and Healon ophthalmic viscosurgical devices for cataract surgery

Purpose

To evaluate the safety and efficacy of DisCoVisc ophthalmic viscosurgical device (OVD, Alcon Laboratories, Inc) with respect to a comparator, Healon OVD (Advanced Medical Optics, Inc).

Patients and methods

In this prospective study, patients with cataracts were randomized to an OVD, and then received phacoemulsification and injection of an intraocular lens. After each surgery, unmasked investigators completed subjective questionnaires about OVD characteristics during each stage of the procedure. Masked technicians evaluated objective safety parameters of intraocular pressure (IOP) and endothelial cell density, with 90 days of follow-up.

Results

The DisCoVisc OVD group (128 eyes) and the Healon OVD group (121 eyes) had statistically similar outcomes for IOP and for endothelial cell loss. Subjectively assessed viscosity was statistically different (P < 0.0001), with Healon OVD most often rated “cohesive” and DisCoVisc OVD most often rated “both dispersive and cohesive”. Workspace maintenance differed between groups (P < 0.0001), with workspace most frequently rated “full chamber maintained” when using DisCoVisc OVD and most frequently rated “workspace maintained” when using Healon OVD. “Flat” or “shallow” workspace ratings occurred only in the Healon OVD group.

Conclusion

DisCoVisc OVD had both cohesive and dispersive properties, and was safe and effective for every stage of cataract surgery.

Use of viscoelastic substance in ophthalmic surgery - focus on sodium hyaluronate

Among viscoelastic substances, sodium hyaluronate has become the most popular for intraocular surgeries since the introduction of Healon^® (sodium hyaluronate 1%, 4 × 10⁶ daltons) in 1979. This review focuses on the recent development of a new generation of sodium hyaluronate agents with new rheologic properties and the relevant new techniques used in cataract, glaucoma, corneal, and vitreoretinal surgeries. The introduction of sodium hyaluronate agents with different rheologic properties has improved the safety and reliability of intraocular surgeries. Although there have been numerous studies reporting the effectiveness of viscoelastic substances in intraocular surgeries, rigorous validation by multi-center randomized control trials is lacking in many cases. At present, no single viscoelastic agent is most suitable to all of the various intraocular surgical techniques. Therefore, ophthalmologic surgeons should keep up with recent developments of viscoelastic agents and relevant surgical techniques for better patient care.

Subjective evaluation of intraoperative performance of DisCoVisc in complex ocular environments

PURPOSE

To subjectively evaluate the intraoperative characteristics of DisCoVisc during phacoemulsification in complex ocular environments.

PATIENTS AND METHODS

In this prospective observational study, two experienced surgeons (ARV and CZ) performed phacoemulsification on 100 consecutive patients with cataract associated with complex ocular environments. Inclusion criteria were eyes with shallow anterior chambers (anterior chamber depth (ACD) of <2.1 mm), inadequate pupillary dilation (3 mm), dense cataract, and white mature cataract. The surgeons subjectively assessed the endpoints at each phase of phacoemulsification and various behavioural aspects of the ophthalmic viscosurgical devices (OVDs) were subsequently evaluated.

RESULTS

The distribution was as follows: eyes with white mature cataract (n=18), eyes with grades 4 and 5 cataract (n=56), eyes with co-existing shallow ACD <2 mm (n=24), and co-existing small pupil size <2 mm (n=18). DisCoVisc behaved like a moderately cohesive viscoelastic in 94% of the cases. Injection of viscoelastic was easy in 38 (38%) eyes and very easy in 62 (62%) eyes. Visualization after the viscoelastic injection was excellent in 74% of the eyes. During phacoemulsification, DisCoVisc was moderately dispersive at all the stages of emulsification. The bag maintenance during IOL implantation was excellent in 56% eyes; IOL implantation was easy in 26% of the eyes and difficult in 20% of the eyes. Surgeons found viscoelastic removal easy in 68% of the eyes. At the time of OVD removal, DisCoVisc behaved like both a dispersive and a cohesive viscoelastic in 96% of the eyes.

CONCLUSION

DisCoVisc provides both cohesive and dispersive properties. DisCoVisc alone, even in complex ocular environments, enabled the surgeon to achieve good intraoperative performance.

Adhesive retention of sodium hyaluronate ophthalmic viscosurgical devices in an acrylic tube model and in porcine-eye corneal endothelium with different irrigation rates

PURPOSE

To evaluate the influence of irrigation rates on the adhesive retention of sodium hyaluronate ophthalmic viscosurgical devices (OVDs) by observation in an acrylic tube system designed to model the epithelial wall and in a porcine-eye experiment.

SETTING

Kohseichuo Hospital, Tokyo, Japan.

METHODS

Commercial sodium hyaluronate OVDs differing in molecular weight were visualized with fluorescein powder. Their adhesive and kinetic characteristics at 2 irrigation rates were visually observed in the acrylic tube model and in a porcine eye under phacoemulsification and aspiration.

RESULTS

In the acrylic tube model, the mean retention time of the low-molecular-weight sodium hyaluronate increased from 2.3 seconds under 78 mL/min irrigation to 27.9 seconds under 45 mL/min irrigation. In the porcine eye, phacoemulsification retention of the same OVD on the corneal endothelial cells was also longer under the low irrigation rate of a 2.2 mm incision than under the higher rate of a 3.5 mm incision.

CONCLUSION

The stable retention of low-molecular-weight sodium hyaluronate in the acrylic tube model at the low irrigation rate corresponded closely with that observed in the porcine eye. This indicates that low-molecular-weight sodium hyaluronate with the low irrigation rates used in procedures such as microincision cataract surgery may effectively protect corneal endothelial cells against surgical risks.

Visco-shell technique with sodium hyaluronate 2.3% in phacoemulsification of Morgagnian cataract

We describe the visco-shell technique with sodium hyaluronate 2.3% (Healon5) to facilitate phacoemulsification in eyes with Morgagnian cataract. Because the entire nucleus is wrapped in a Healon5 visco-shell, phacoemulsification can be performed safely without damaging the corneal endothelium and the posterior capsule.

DisCoVisc versus the soft-shell technique using Viscoat and Provisc in phacoemulsification: randomized clinical trial

PURPOSE

To compare the effects and outcomes of DisCoVisc (hyaluronic acid 1.6%-chondroitin sulfate 4.0%) with those of the soft-shell technique using Viscoat (sodium hyaluronate 3.0%-chondroitin sulfate 4.0%) and Provisc (sodium hyaluronate 1.0%) in phacoemulsification.

SETTING

Iladevi Cataract & IOL Research Centre, Ahmedabad, India.

METHODS

This prospective randomized clinical trial comprised 100 eyes having phacoemulsification by the same surgeon using a standardized technique. Eyes were randomly assigned to DisCoVisc (Group 1) or Viscoat and Provisc (Group 2). Preoperative and postoperative examinations included absolute change in pachymetry, percentage difference in endothelial cell density (ECD) and coefficient of variation (CV), and anterior segment inflammation.

RESULTS

The mean postoperative central corneal thickness (CCT) in Group 1 and Group 2 was 590.96+/-46.05 microm and 586.94+/-50.57 microm, respectively, at 1 day; 554.14+/-35.45 microm and 551.65+/-37.69 microm, respectively, at 7 days; and 533.74+/-29.12 microm and 536.44+/-35.59 microm, respectively, at 1 month. The between-group differences in CCT were not statistically significant. At 3 months, the mean ECD was 2427.06+/-243.26 cells/mm2 and 2475.30+/-222.83 cells/mm2, respectively, and the mean CV, 42.38+/-7.94 cells/mm2 and 41.66+/-7.71 cells/mm2, respectively. There was no significant difference in the mean ECD between preoperatively and 3 months postoperatively or in corneal thickness between preoperatively and 1, 7, and 30 days postoperatively.

CONCLUSION

A single injection of DisCoVisc was effective, and its postoperative outcomes were comparable to those of combined Viscoat and Provisc.