Removal of viscoelastic materials after experimental cataract surgery in vitro

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.

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.

Acute Infectious Endophthalmitis After Cataract Surgery: Epidemiological Characteristics, Risk Factors and Incidence Trends, 2008-2019

Objective

Intended to investigate the epidemiological characteristics, risk factors and incidence trend of endophthalmitis after cataract surgery in recent 12 years.

Methods

A retrospective study was conducted on the patients who underwent cataract surgery in Qingdao Eye Hospital from January 1, 2008, to December 31, 2019, including age, sex, history of diabetes, intraoperative operation and complications. In addition, the related risk factors and incidence trend of acute infective endophthalmitis were analyzed. The incidence of endophthalmitis and its related factors were analyzed by univariate and multivariate logistic regression analysis.

Results

A total of 55,612 cases of cataract surgery were performed in our hospital in 12 years, and 42 cases of acute infective endophthalmitis occurred (the incidence rate was 0.076%). The average occurrence time was 10.57 days ± 11.17, with eye pain as the main complaint and anterior chamber fibrin exudation as the main clinical manifestation. In addition, there were eight cases of anterior chamber hypopyon and 18 cases of vitreous reaction, the results of anterior aqueous humor or vitreous fluid culture in 10 patients were positive. Univariate analysis showed that intraoperative rupture of posterior capsule, non-use of antibiotics and non-use of behind-the-lens washout were the risk factors of infectious endophthalmitis after cataract surgery (P=0.032, P=0.000, P=0.000). Besides, multivariate logistic regression analysis showed that intraoperative rupture of posterior capsule was the main risk factor.

Conclusion

The occurrence of endophthalmitis after cataract surgery is mainly related to intraoperative rupture of posterior capsule, absence of antibiotics and behind-the-lens washout. In addition, the incidence of endophthalmitis after cataract surgery decreased during the past 12 years.

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.

Assessment of Post-Operative Pseudophakic Glaucoma by Ultrasound Biomicroscopy

Purpose

Pseudophakic glaucoma is a secondary glaucoma in which intra-ocular pressure is elevated following cataract removal. The current study aimed to evaluate the role of ultrasound biomicroscopy (UBM) in assessing post-operative pseudophakic glaucoma.

Patients and Methods

This is a case series, prospective, observational and analytical study. It included 29 eyes of 29 patients with post-operative pseudophakic glaucoma. The patients were evaluated by medical history, detailed ophthalmologic examination and UBM.

Results

UBM examination has unmasked different causes of pseudophakic glaucoma. The detected causes were classified into 3 main groups, including intraocular lens (IOL)-related causes, lens remnants and intra-ocular inflammation. Haptic-related causes were present in 9 eyes, while 6 eyes had decentered or tilted IOLs. Soemmering's ring was the main cause in 3 eyes while in one eye the cause was lens particle in the anterior chamber (AC). Silicone oil in AC with seclusio pupillae was the main cause in one eye. Peripheral anterior synechiae were detected in 8 eyes while, posterior synechiae were evident in 7 eyes. Uveitis induced by anterior chamber IOL (ACIOL) was found in 3 eyes and one eye had peripheral anterior synechiae due to neovascular glaucoma.

Conclusion

UBM is a helpful diagnostic tool to evaluate causes of pseudophakic glaucoma through adequate visualization of different angle structures.

Endophthalmitis after cataract surgery: Effect of behind-the-lens washout

PURPOSE

To analyze the outcomes of cataract surgery with emphasis on the relationship between surgery-related factors and the incidence of postoperative infectious endophthalmitis.

SETTING

Ninety-three surgical sites in Japan.

DESIGN

Prospective case series.

METHODS

Eyes that were scheduled to have cataract surgery from January 20 to September 30, 2014, were included. Phacoemulsification and implantation of a single-piece hydrophobic acrylic foldable intraocular lens (IOL) were performed. Patients were followed for 2 months.

RESULTS

Of the 9720 eyes enrolled, 9100 (93.6%) completed a 2-month follow-up. Three cases (0.033%) developed infectious endophthalmitis (95% confidence interval [CI], 0.000-0.070). The incidence of endophthalmitis was significantly associated with the removal method of ophthalmic viscosurgical devices (OVDs) after IOL implantation. The incidences of endophthalmitis in cases with and without the behind-the-lens technique were 0% (0/6147; 95% CI, 0%) and 0.084% (3/3570; 95% CI, 0.000-0.179), respectively, with a significant difference between them (P = .050, Fisher exact test). The incidence of infectious endophthalmitis did not correlate with any other patient-related and surgery-related factors.

CONCLUSION

The behind-the-lens technique to wash and clear the capsular bag for OVD removal significantly reduced the incidence of infectious endophthalmitis.

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.

Early postoperative intraocular pressure elevation following cataract surgery

PURPOSE OF REVIEW

The aim of this review was to assess the risk factors and course of postoperative intraocular pressure (IOP) increase in order to determine the optimal the treatment.

RECENT FINDINGS

Early postoperative IOP elevation following cataract surgery is a frequent adverse event, and might represent 88% early postoperative complications. The risk factors for IOP elevation following phacoemulsification cataract surgery include residual viscoelastic material, resident performed surgery, glaucoma, pseudoexfoliation syndrome, axial length over 25 mm, tamsulosin intake, topical steroid application in steroid responders. A day-1 postoperative follow-up might be questioned, even in glaucoma patients, as in IOP spikes the topmost IOP elevation occurs 3-4 h postoperatively.

SUMMARY

Several IOP-lowering agents have been evaluated, but none has completely prevented the occurrence of IOP spikes. We recommend applying a combination of dorzolamide/timolol and brinzolamide topically in high-risk patients, particularly with preexisting optic nerve damage. Corticosteroid cessation usually results in a reduction of the IOP to normal levels in steroid responders. Additional studies are required to assess the optimal treatment, especially in glaucoma patients.

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.

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 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).

Intraocular pressure elevation during early postoperative period after secondary intraocular lens implantation in children and adolescents

PURPOSE

To look at the intraocular pressure (IOP) spike in the early postoperative period after secondary intraocular lens (IOL) implantation in children.

SETTING

Miles Center for Pediatric Ophthalmology, Medical University of South Carolina, South Carolina, USA.

DESIGN

Retrospective chart review.

METHODS

The postoperative day-1 examination of patients having secondary IOL implantation by the same surgeon was reviewed for an IOP greater than 26 mm Hg. In patients with an IOP spike, the medical history and examination findings that might be associated with the rise were evaluated.

RESULTS

Review of 85 patient charts (133 eyes) identified 9 eyes that developed an IOP spike during the early postoperative period. Six eyes were symptomatic, with symptoms including pain, ocular discomfort, nausea, and emesis, and 6 eyes had preoperative aphakic glaucoma, which was controlled with medication. Six of 22 eyes (27%) with preoperative aphakic glaucoma and 3 of 111 eyes (3%) without glaucoma (P<.001) developed an acute IOP rise (relative risk, 10.1).

CONCLUSIONS

The high incidence of a symptomatic early IOP spike in patients with aphakic glaucoma warrants meticulous ophthalmic viscosurgical device removal at the end of surgery, consideration of the routine use of prophylactic topical and/or systemic glaucoma medication, and monitoring during the early postoperative period.

Viscoat versus Visthesia during phacoemulsification cataract surgery: corneal and foveal changes

Background

Ophthalmic viscosurgical devices (OVDs) are widely used in phacoemulsification cataract surgery to maintain adequate intraocular space, stabilize ocular tissue during the operation and decrease the possible damage of the corneal endothelium. Our study has the purpose to compare the corneal and foveal changes of Viscoat and Visthesia in patients undergoing uneventful phacoemulsification cataract surgery.

Methods

Participants in our study were 77 consecutive patients, who were randomized into two groups based on type of OVD used during phacoemulsification: Viscoat or Visthesia. All patients underwent a complete ophthalmological examination i.e., measurement of best corrected visual acuity (BCVA) by means of Snellen charts, intraocular pressure examination by Goldmann tonometry, slit lamp examination, fundus examination, optical coherence tomography, specular microscopy and ultrasound pachymetry preoperatively and at three time points postoperatively (day 3, 15, 28 postoperatively). The differences in baseline characteristics, as well as in outcomes between the two groups were compared by Mann-Whitney-Wilcoxon test and Student's t-test, as appropriate.

Results

Intraoperatively, there was no statistically significant difference in the duration of the ultrasound application between the two groups, while Viscoat group needed more time for the operation performance. It is also worthy to mention that Visthesia group exhibited less intense pain than patients in Viscoat group. Postoperatively, there was a statistically significant difference in central corneal thickness, endothelial cell count and macular thickness between the two groups, but BCVA (logMAR) did not differ between the two groups.

Conclusions

Our study suggests that Viscoat is more safe and protective for the corneal endothelium during uneventful phacoemulsification cataract surgery, while Visthesia is in superior position regarding intraoperative pain. Patients of both groups acquired excellent visual acuity postoperative. Finally, this is the first study comparing OVDs in terms of macular thickness, finding that Visthesia cause a greater increase in macular thickness postoperatively than Viscoat, although it reaches normal ranges in both groups.

Increased intraocular pressure on the first postoperative day following resident-performed cataract surgery

PURPOSE

The aim of this study was to investigate the incidence of intraocular pressure (IOP) elevation after resident-performed cataract surgery and to determine variables, which influence postoperative day 1 (POD1) IOP.

METHODS

In all, 1111 consecutive cataract surgeries performed only by training residents between 1 July 2001 and 30 June 2006 were included. Elevated IOP was defined as ≥23 mm Hg. Surgeries were classified according to the presence of POD1-IOP elevation. Fisher's exact test and Student t-test were used to compare both groups. Multivariate analyses using generalized estimating equations were performed to investigate predictor variables associated with POD1-IOP elevation.

RESULTS

The average preoperative IOP was 16.0±3.2 mm Hg and the average POD1-IOP was 19.3±7.1 mm Hg, reflecting a significant increase in IOP (P<0.001, paired t-test). The incidence of POD1-IOP elevation ≥23 mm Hg was 22.0% (244/1111). Presence of glaucoma and ocular hypertension, higher preoperative IOP, and longer axial length were frequently encountered variables in the POD1-IOP elevation group (all P<0.05). Using a multivariate analysis, presence of glaucoma (P=0.004, OR=2.38; 95% confidence interval (95% CI)=1.31-4.30), presence of ocular hypertension (P=0.003, OR=6.09; 95% CI=1.81-20.47), higher preoperative IOP (P<0.001, OR=3.73; 95% CI=1.92-7.25), and longer axial length (P=0.01, OR=1.15; 95% CI=1.03-1.29) were significant predictive factors for POD1-IOP elevation.

CONCLUSIONS

IOP elevation on the first postoperative day following resident-performed cataract surgery occurred frequently (22.0%). Increased early postoperative IOP was associated with presence of glaucoma and ocular hypertension, higher preoperative IOP, and longer axial length.

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.

Hydroxyl Radical Scavenging Activity of a New Ophthalmic Viscosurgical Device

PURPOSE

To quantify the hydroxyl radical scavenging activity of a new ophthalmic viscosurgical device (OVD) based on sodium hyaluronate and hydroxypropylmethylcellulose (named VISC28) in comparison with Viscoat, Healon, and Amvisc Plus.

METHODS

The hydroxyl radicals that represent the principal free-radical species generated during phacoemulsification were produced by the Fenton reaction, and the scavenging activity of the tested viscoelastic substances was evaluated in vitro by the 2-deoxy-D-ribose (2-DR) oxidation method that produces the thiobarbituric acid-malondialdehyde (TBA-MDA), complex. An aliquot of viscosurgical formulation was added to phosphate buffer and mixed with 2-DR, Fe2 +/ethylenediaminetetraacetic acid (EDTA), and H2O2. The sample mix was incubated and thiobarbituric acid-trichloroacetic acid solution was added. The sample was then incubated for 30 min, and a chromatographic analysis was performed to quantify the TBA-MDA complex. The data were expressed as micromoles of MDA per milliliter of sample.

RESULTS

All tested OVDs showed a marked hydroxyl radical scavenging activity. The MDA level was significantly lower in VISC28 (0.045 +/- 0.007 micromol/ml) compared with Viscoat (0.070 +/- 0.012 micromol/ ml, p < 0.05), Amvisc Plus (0.111 +/- 0.008 micromol/ml, p < 0.001), and Healon (0.175 +/- 0.016 micromol/ml, p < 0.001). A reduced scavenging activity was shown by VISC28 phosphate-buffered solution (PBS) (no TRIS and no sorbitol) compared with VISC28 (p < 0.001).

CONCLUSIONS

The new OVD, VISC28, showed significantly higher hydroxyl radical inhibition compared with the other viscosurgical formulations. The following rank order for the scavenging activity was established: VISC28 > Viscoat > Amvisc Plus > Healon.

Viscoanaesthesia in cataract surgery: a prospective, randomized clinical trial

PURPOSE

We aimed to compare viscoanaesthesia (VisThesia) with intracameral lidocaine in cataract surgery carried out under topical anaesthesia.

METHODS

In this prospective study 98 patients were randomly assigned to receive VisThesia (group 1, n = 49) or 0.5 cc of 1% unpreserved lidocaine (group 2, n = 49). All surgery was carried out by one surgeon using clear corneal technique. Pachymetry, the status of the cornea and anterior chamber, and intraocular pressure (IOP) were checked pre- and postoperatively.

RESULTS

Mean pain scores were 0.12 (maximum: 3) in group 1 and 0.37 in group 2; the difference between the groups was not statistically significant (95% confidence interval [CI] 0.003-0.487; p = 0.05). A total of 48 patients in group 1 (98%) and 49 in group 2 (100%) reported no discomfort or only mild discomfort. No significant differences in flare and cells in the anterior chamber or IOP were found between the two study groups. There was a significantly greater frequency of corneal oedema in group 1 (p = 0.001). Postoperative central corneal thickness values were also significantly higher in group 1 (95% CI 11.64-57.24; p = 0.003).

CONCLUSIONS

Results suggest that viscoanaesthesia provides a level of comfort during cataract surgery under topical anaesthesia similar to that facilitated by intracameral lidocaine. However, patients who are given viscoanaesthesia may have increased risk for postoperative corneal oedema.

Update on veterinary cataract surgery

PURPOSE OF REVIEW

The purpose of this review is not to specifically discuss the techniques of veterinary cataract surgery, but rather to emphasize some of the differences between the veterinary and human cataract patients, procedures and outcomes.

RECENT FINDINGS

In general, veterinary cataract surgery has more similarities than differences when compared to its human counterpart. This is especially true when comparing pediatric cataract patients. Veterinary cataract surgery has changed dramatically in recent years with regards to surgical technique, ocular pharmacology, viscoelastic devices, phacoemulsification, and the most recent advancement, intraocular lens implantation for dogs, cats, and horses.

SUMMARY

It is hoped that the exchange of information between the human and veterinary specialties can be of benefit to both groups as we all work to improve outcomes and resolve complications.

A case of cataract surgery without pupillary device in the eye with iridoschisis

Purpose

To introduce a case of iridoschisis patient who underwent cataract surgery successfully without pupil device.

Methods

A 64-year-old female who showed iridoschisis of her both eyes underwent cataract operation at her right eye without a pupillary device. The preoperative and postoperative ophthalmologic examinations including visual acuity, intraocular pressure, reaction of anterior chamber, and degree of damage on iris was evaluated respectively.

Results

Cataract surgery was performed under topical anesthesia through a clear corneal incision. Iris fibrils were held in place by ophthalmic viscosurgical device (OVD, sodium hyaluronate 3%-sodium chondroitin sulfate 4%, Viscoat®) that was injected into the anterior chamber. A small capsulorrhexis was made and the nucleus was delivered with low-power phacoemulsification, most of which was performed under the anterior capsule. The iris came into contact with the OVDs only and received no mechanical trauma. There were no intraoperative complications such as tear of the iris, hyphema, loss of mydriasis, or rupture of the posterior lens capsule. The edema of corneal stroma and inflammation of anterior chamber was shown at immediate-postoperative period, but completely subsided 2 weeks later. The visual acuity showed improvement from 20/400 to 20/30.

Conclusions

In iridoschisis patients, there is a risk of aspiration of iris fibers during cataract surgery. With adequate use of OVD and careful modulation of surgical devices, cataract surgery was successfully performed without using extra pupil-supporting device.

Comparison of the effect of Viscoat and DuoVisc on postoperative intraocular pressure after small-incision cataract surgery

PURPOSE

To evaluate the effect of Viscoat (sodium chondroitin sulfate 4%-sodium hyaluronate 3%) and DuoVisc (Viscoat and Provisc [sodium hyaluronate 1%]) on postoperative intraocular pressure (IOP) after bilateral small-incision cataract surgery.

SETTING

Department of Ophthalmology, University of Vienna, Vienna, Austria.

METHODS

This prospective randomized study comprised 60 eyes of 30 consecutive patients with age-related cataract in both eyes. Each patient's eyes were randomly assigned to receive Viscoat or DuoVisc during cataract surgery. DuoVisc is a packet containing 2 ophthalmic viscosurgical devices (OVDs): the dispersive Viscoat, which was used for intraocular lens (IOL) implantation. In the Viscoat group, the Viscoat was used during the entire surgery. The intraocular pressure (IOP) was measured preoperatively as well as 1, 6, and 20 to 24 hours postoperatively.

RESULTS

One and 6 hours postoperatively, the mean IOP was significantly higher in the Viscoat group than in the DuoVisc group (25.8 mm Hg and 20.5 mm Hg, respectively, at 1 hour and 24.7 mm Hg and 21.1 mm Hg, respectively, at 6 hours) (P<.05). At 20 to 24 hours, the mean IOP was not statistically significantly different between the 2 groups. Intraocular pressure spikes to 30 mm Hg or higher occurred in 4 eyes in the DuoVisc group and 11 eyes in the Viscoat group (P<.05).

CONCLUSIONS

Viscoat caused significantly higher IOP increases and significantly more IOP spikes than DuoVisc in the early postoperative period. Therefore, if Viscoat is used during cataract surgery, an additional cohesive OVD should be used for IOL implantation.

Soft-shell technique using Viscoat and Healon 5: a prospective, randomized comparison between a dispersive-viscoadaptive and a dispersive-cohesive soft-shell technique

PURPOSE

To compare the efficacy of the dispersive-viscoadaptive soft-shell technique using Viscoat and Healon 5 to the dispersive-cohesive soft-shell technique in reducing corneal endothelial cell damage during cataract surgery.

METHODS

In this prospective randomized study, 207 eyes of 171 cataract patients underwent phacoemulsification using the dispersive-viscoadaptive soft-shell technique (V-group, 102 eyes) with Viscoat and Healon5 or the dispersive-cohesive soft-shell technique (C-group, 105 eyes) with Viscoat and a cohesive agent (Opegan-Hi). Each group was divided into two subgroups depending on the amount of ultrasound (%Min) used during phacoemulsification. Corneal endothelial cell density was examined preoperatively and 3 months postoperatively. The endothelial cell loss was compared between the two groups, and also between the subgroups.

RESULTS

The mean endothelial cell loss 3 months after surgery was 8.4 +/- 5.6% standard deviation (SD) in the V-group and 8.2 +/- 6.2% in the C-group (P = 0.787). In the subgroups with ultrasound of 10 %Min or less, the mean endothelial cell loss 3 months after surgery was 6.6 +/- 4.6% in the V-group and 5.5 +/- 5.0% in the C-group (P = 0.104). In the subgroups with ultrasound of over 10 %Min, this value was 10.6 +/- 6.3% in the V-group and 11.9 +/- 5.7% in the C-group (P = 0.413). The correlation coefficient of the endothelial cell loss rate and %Min was 0.245 (P = 0.0129) in the V-group and 0.501 (P < 0.0001) in the C-group.

CONCLUSION

The dispersive-viscoadaptive soft-shell technique is as effective as the dispersive-cohesive soft-shell technique in protecting corneal endothelial cells during phacoemulsification regardless of the amount of ultrasound energy used.

The influence of viscoelastic substances on the corneal endothelial cell population during cataract surgery: a prospective study of cohesive and dispersive viscoelastics

PURPOSE

To compare the ability of cohesive and dispersive ophthalmic viscoelastic devices (OVDs) to protect the corneal endothelium following in-the-bag phacoemulsification with implantation of a foldable posterior chamber intraocular lens (IOL).

METHODS

In a prospective single-masked randomized study, 60 eyes of 60 cataract patients were assigned to three groups of 20 patients each, according to which OVD was used: Celoftal, Vitrax or Healon. The corneal response to surgery was evaluated by measuring the endothelial cell loss, the variation in mean cell area of the endothelial cells (CV), the frequency of hexagonal cells, and the central corneal thickness. Data were recorded preoperatively and 3 months postoperatively.

RESULTS

Preoperatively, no significant difference was observed in cell count, CV, hexagonal pattern or pachymetry among groups. Postoperatively, all three groups had a significant decrease in cell count, but the decrease was significantly less in the Vitrax group (6.97%) than in the Celoftal (18.03%) and Healon groups (18.46%). No changes in CV, hexagonality or corneal thickness were observed within any of the three groups or among the groups. There was an equal and significant increase in visual acuity.

CONCLUSIONS

Phacoemulsification with implantation of a posterior chamber lens is known to affect the density and morphology of corneal endothelial cells. Viscoelastics facilitate cataract surgery and protect the corneal endothelium during the procedure. Choosing a dispersive hyaluronate OVD during the phaco procedure may allow for protection of the endothelial cells while suppressing the formation of free radicals. This may be the reason for the superior protective effect on the corneal endothelial cells of Vitrax compared with Celoftal and Healon.

In vitro behavior of ophthalmic viscosurgical devices during phacoemulsification

PURPOSE

To evaluate the behavior and aspiration of several ophthalmic viscosurgical devices (OVDs) during phacoemulsification.

SETTING

Department of Ophthalmology, Tokyo Dental College Suidobashi Hospital, Tokyo, Japan.

METHODS

Cohesive OVDs (sodium hyaluronate 1.0% [Healon and Provisc]), dispersive OVDs (sodium hyaluronate 3.0%-chondroitin sulfate 4.0% [Viscoat]), and new-generation OVDs such as viscoadaptive (sodium hyaluronate 2.3% [Healon5]) and viscodispersive (hyaluronic acid 1.65%-chondroitin sulfate 4.0% [DisCoVisc]) OVDs, were stained with fluorescein sodium. The movement of the OVDs during simulated cataract surgery was recorded in porcine eyes under an operating microscope and with a side-view video camera. The initial and complete aspiration times of each OVD during phacoemulsification using 20 and 40 mL/min flow rates and sleeves and the removal times using the irrigation and aspiration (I/A) tip at the end of surgery were evaluated from the recorded videos.

RESULTS

The complete aspiration time of the cohesive OVDs was less than 3 seconds but up to 20 seconds with a low flow rate of 20 mL/min with a smaller sleeve. Other OVDs remained in the anterior chamber during phacoemulsification with both flow rates. The removal time for cohesive OVDs was less than 4 seconds and for new-generation OVDs, 10 to 15 seconds. The dispersive OVD required a significantly (P<.05) longer removal time than other OVDs.

CONCLUSIONS

Cohesive OVDs are removed easily during phacoemulsification; however, the aspiration rate can be affected by fluidics. New-generation OVDs, such as Healon5 and DisCoVisc, remained in the anterior chamber during phacoemulsification and were removed easily by I/A at the end of surgery. The behavior of these OVDs is preferable 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.

Quantitative thermographic analysis of viscoelastic substances in an experimental study in rabbits

PURPOSE

To measure the temperature parameters on the corneal surface during the delivery of standardized ultrasound energy assisted with ophthalmic viscosurgical devices (OVDs) or different temperatures of irrigating solutions in an experimental animal model.

SETTING

Department of Ophthalmology and Visual Rehabilitation, Medical University of Lodz, and Central Institute for Labor Protection, National Research Institute, Warsaw, Poland.

METHODS

Thirty rabbits (60 eyes) were randomly divided into 6 groups in which different OVD or balanced salt solutions (BSS) were used: group 1: Viscoat (sodium hyaluronate 3%-chondroitin sulfate); group 2: Provisc (sodium hyaluronate 1%); group 3: soft-shell technique; group 4: Celoftal (hydroxypropyl methylcellulose 2%); group 5: BSS 22 degrees C; and group 6: BSS 4 degrees C. After the nucleus and lens cortex were removed, the anterior chamber was filled with OVD or BSS and a phaco tip was introduced into the pupillary plane and switched on. The same phaco tip parameters were used in all groups. For thermographic measurements (ie, maximal temperature [MT], dynamic rise in temperature [DRT], and time when the maximal level of temperature [TMLT] was achieved), a thermocamera was used.

RESULTS

Mean preoperative temperature on the rabbit corneal surface was 22.76 degrees C +/- 1.48 degrees C (SD). Working with a phaco tip increased the temperature in each group. A significantly higher MT was observed in group 5 (27.85 degrees C +/- 0.52 degrees C), followed by group 2 (27.75 degrees C +/- 0.54 degrees C), group 3 (27.74 degrees C +/- 0.46 degrees C), and group 4 (27.25 degrees C +/- 0.60 degrees C), than in group 6 (26.81 degrees C +/- 0.34 degrees C) and group 1 (26.52 degrees C +/- 0.48 degrees C) (P<.05). Significantly higher values of DRT and shorter TMLT values were observed in group 5 (1.16 degrees C/s +/- 0.42 degrees C/s, 4 seconds) and group 6 (0.91 degrees C/s +/- 0.13 degrees C/s, 5 seconds) than in groups 2, 3, 1, and 4 (0.09 degrees C/s +/- 0.07 degrees C/s, 30 seconds; 0.08 degrees C/s +/- 0.04 degrees C/s, 40 seconds; 0.07 degrees C/s +/- 0.03 degrees C/s, 45 seconds; 0.06 degrees C/s +/- 0.02 degrees C/s, 50 seconds, respectively) (P<.0001).

CONCLUSIONS

Currently used OVDs potentially offer different levels of protection against the increase in temperature that occurs during phacoemulsification. Therefore, the surgeon should consider this aspect when choosing an OVD, particularly in difficult cases (ie, hard nucleus, shallow anterior chamber, endothelial abnormalities).

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.

Free radical development in phacoemulsification cataract surgery

Phacoemulsification and aspiration (PEA) has become the most popular cataract surgery, due to the establishment of safe surgical techniques and development of associated instruments. However, corneal endothelial damage still represents a serious complication, as excessive damage can lead to irreversible bullous keratopathy. In addition to causes such as mechanical or heat injuries, free radical formation due to ultrasound has been posited as another cause of corneal endothelium damage in PEA. Ultrasound in aqueous solution induces cavitation, directly causing water molecule disintegration and resulting in the formation of hydroxylradicals, the most potent of the reactive oxygen species. Considering the oxidative insult to endothelial cells caused by free radicals, their presence in the anterior chamber may represent one of the most harmful factors during these procedures. Indeed, some researchers have recently started to evaluate PEA from the perspective of oxidative stress. Conversely, the major ingredient in ophthalmic viscosurgical devices (OVDs), which are indispensable for maintaining the anterior chamber in PEA surgery, is sodium hyaluronate, a known free radical scavenger. OVDs can thus be expected to provide some anti-free radical effect during PEA procedures. In addition, since commercially available OVDs display different properties regarding retention in the anterior chamber during PEA, the anti-free radical effect of OVDs is likely to depend on behavior during irrigation and aspiration. The present study followed standard PEA procedures in an eye model and measured hydroxylradicals in the anterior chamber using electron spin resonance. The kinetics of free radical intensity and effects of several OVDs during clinical PEA were also demonstrated. These studies may be of significance in re-evaluating OVDs as a chemical protectant for corneal endothelium, since the OVD has thus far only been regarded as a physical barrier. In addition, many reports about corneal endothelium damage during PEA have been published, but objective evaluation of various damaging factors has been difficult. The present assay of free radicals in a simulation of clinical PEA offers the first method to quantitatively assess stress on the corneal endothelium.

Agents for intraocular surgery

No single viscoelastic material has all the properties required for every surgical procedure. Ophthalmic surgeons should be familiar with the advantages and disadvantages of several viscoelastics and realize the limitations encountered if the surgeon chooses to rely on a single viscoelastic. It is possible in the future that newer viscoelastics may become available offering aspects of cohesive and dispersive properties that make them easy to remove and not associated with postoperative hypertension. Investigation into other types of viscoelastic materials, such as poly-acrylamide (Orcolon) [33,51,52], human collagen [33,53], polytriethylene-glycol monomethacrylate, and polyglycerol monomethacrylate [48], may result in the availability of synthetic viscoelastic materials. Rethinking how we use viscoelastics may also be indicated. The approach of a single or repeat instillation of a viscoelastic only to have it aspirated during the procedure could be modified by using a continuous infusion ofa dilute viscoelastic [54]. One study diluted hyaluronic acid to a concentration of 0.06% to 0.12% and maintained continuous infusion of the viscofluid through the PE irrigation line [54]. It has been suggested that this may reduce turbulence and improve tissue protection [54].

Relationship of immediate intraocular pressure rise to phaco-tip ergonomics and energy dissipation

PURPOSE

To evaluate the rise in intraocular pressure (IOP) after phacoemulsification using a straight microtip or a Kelman microtip and its relationship to phaco energy delivered to the eye.

SETTING

Iladevi Cataract & IOL Research Center, Ahmedabad, India.

METHODS

This prospective randomized study comprised 48 consecutive age- and sex-matched patients with senile cataract. Inclusion criteria included older than 45 years and presence of any type of cataract from grade I to III. The patients were divided into 2 groups: straight microtip and Kelman microtip. Each group comprised 13 men and 11 women. The mean age was 58.29 years +/- 6.46 (SD) in the straight microtip group and 60.05 +/- 8.45 years in the Kelman microtip group. The IOP was measured preoperatively and postoperatively with a pneumotonometer and applanation tonometer. One surgeon performed all operations using a standardized surgical technique and topical anesthesia. The intraoperative mean phaco power and ultrasound (US) time were noted. The effective phaco time (EPT), percentage of IOP rise, and wound-site thermal injury (mild, moderate, or severe) were calculated. The correlation between the EPT and percentage of rise in IOP was evaluated using correlation coefficients and the paired t test.

RESULTS

The mean preoperative IOP was 13.73 +/- 2.89 mm Hg in the straight microtip group and 15.14 +/- 2.60 mm Hg in the Kelman microtip group. The mean US time was 239.4 +/- 1.61 seconds and 238.2 +/- 1.48 seconds, respectively. The mean phaco power was 17.37% +/- 3.28% in the straight microtip group and 17.10% +/- 5.26% in the Kelman microtip group and the mean EPT, 39.06 +/- 2.28 seconds and 40.08 +/- 0.24 seconds, respectively (P =.412). The mean rise in IOP was 111.60% +/- 37.83% in the straight microtip group and 91.29% +/- 31.85% in the Kelman microtip group. The difference between groups was significant (P<.05). The correlation coefficient between the EPT and percentage of IOP rise was significant in both groups: 0.3823, straight microtip group (P<.05); 0.514, Kelman microtip group (P<.01). Wound-site thermal injury was noted in 3 patients in the straight microtip group and 1 patient in the Kelman microtip group.

CONCLUSIONS

Although the amount of phaco energy dissipated in the eye was the same between the 2 groups, the percentage of IOP rise was greater with the straight microtip. The rise in IOP was correlated with the dissipated phaco energy.

Ocular surgical pharmacology: corneal endothelial safety and toxicity

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

Intraocular pressure development after cataract surgery: a prospective study in 50 dogs (1998-2000)

OBJECTIVE

To study the course of intraocular pressure (IOP) after cataract surgery in 50 dogs.

DESIGN

Prospective study.

ANIMALS

Fifty dogs without preoperative ocular hypertension were selected for cataract surgery.

METHODS

All dogs underwent cataract surgery: 25 by manual extracapsular extraction and 25 by phacoemulsification. For each dog, intraocular pressure was measured before surgery, and 1, 3, 5, 18 h, 1 week and 1 month post surgery.

RESULTS

No significant difference of mean intraocular pressure between the two surgical methods was observed for each time measurement. Nine dogs had postoperative hypertension (IOP > 25 mmHg) during the first 5 hours post surgery. Incidence of postoperative hypertension was not significantly different with manual extracapsular extraction (16%) vs. phacoemulsification (20%). A decrease of mean IOP was observed 1 h after surgery (8.49 mmHg vs. 10.91 mmHg), then an increase 3 and 5 h post surgery (12.3 and 13.32 mmHg, respectively). At 18 h, 1 week and 1 month post surgery, mean IOP decreased. Mean IOP was 10.38, 10.38 and 8.84 mmHg, respectively.

CONCLUSION

In this study incidence of POH is not high. However, a follow-up of IOP in the first hours after cataract surgery is required to avoid complications of the retina and optic nerve and to administer hypotensive treatment if necessary.

Corneal endothelial cell protection with a dispersive viscoelastic material and an irrigating solution during phacoemulsification: low-cost versus expensive combination

PURPOSE

To evaluate the protective effect on corneal endothelial cells of a low-cost and an expensive combination of a dispersive viscoelastic material and an irrigating solution during phacoemulsification.

SETTING

Department of Ophthalmology, University of Vienna, Vienna, Austria.

METHODS

This prospective randomized examiner- and patient-masked study comprised 90 eyes of 45 consecutive patients with age-related cataract in both eyes. For each patient, the first eye was randomly assigned to receive hydroxypropyl methylcellulose 2% (Ocucoat) and Ringer's solution (low-cost combination) or sodium chondroitin sulfate 4%-sodium hyaluronate 3% (Viscoat) and an enriched balanced salt solution (BSS Plus) (expensive combination) during phacoemulsification. The contralateral eye received the other treatment. Endothelial cell function was evaluated by measuring corneal thickness (CT) using partial coherence interferometry, morphology assessment, and endothelial cell counts.

RESULTS

The acute postoperative increase in CT was +9.8 microm in the low-cost group and +10.9 microm in the expensive group; the difference between groups was not significant. After 1 month, the CT still differed significantly from baseline in the low-cost group. Three months after surgery, the CT had returned to baseline values in both groups. There was no significant between-group difference in endothelial cell counts or morphology.

CONCLUSIONS

During phacoemulsification in a nonselected patient population, there was no difference in acute postoperative corneal edema and endothelial cell morphology after 3 months between a Viscoat and BSS Plus combination and an Ocucoat and Ringer's solution combination. Eyes receiving the expensive combination had marginally faster recovery of corneal swelling by 3 months. However, the cost of Viscoat and 500 mL BSS Plus is 5 times that of Ocucoat and Ringer's solution.

Intraocular Pressure in Myopic Patients After Worst-Fechner Anterior Chamber Phakic Intraocular Lens Implantation

PURPOSE

To assess intraocular pressure measured with a Goldmann tonometer over a period of 1 year after implantation of a Worst-Fechner anterior chamber phakic intraocular lens to correct myopia of -7.00 D or more.

METHODS

We performed a prospective, non-masked study of 100 patients (100 myopic eyes) who had a Worst-Fechner phakic intraocular lens implanted to correct myopia of -7.00 D or greater. Central corneal Goldmann tonometry was performed before surgery and 1, 3, 6, and 12 months after surgery. The influence of different variables was assessed.

RESULTS

IOP showed a significant increase of a mean 2.1 mmHg at 3 months after surgery (P=.001). There was not a statistically significant difference between IOP before surgery and 6 months after PIOL implantation (P=.244) or 1 year after surgery (P=.845). In one eye, the lens was explanted 11 months after surgery because of the presence of ocular hypertension. No variables studied showed a statistically significant difference from before to after surgery.

CONCLUSIONS

Worst-Fechner anterior chamber phakic intraocular lens implantation led to a slight transitory increase of intraocular pressure during the first 3 months after surgery, but returned to preoperative levels by 6 months after implantation.

Viscoanesthesia. Part III: removal time of OVD/viscoanesthetic solutions from the capsular bag of postmortem human eyes

PURPOSE

To investigate and evaluate the removal time of various ophthalmic viscosurgical device (OVD)/viscoanesthetic solutions containing sodium hyaluronate 1.5% with different concentrations of lidocaine (0.5%, 1.0%, and 1.65%).

SETTING

Center for Research on Ocular Therapeutics and Biodevices, Storm Eye Institute, Medical University of South Carolina, Charleston, South Carolina, USA.

METHODS

Six postmortem human eyes were prepared per the Miyake-Apple posterior video technique. Capsulorhexis, hydrodissection/delineation, and nuclear emulsification were performed, followed by thorough cleaning of the capsular bag using an irrigation/aspiration (I/A) tip. The time and ease of removal of 4 solutions from the capsular bag were evaluated. The solutions were Ophthalin Plus (sodium hyaluronate, 15 mg/mL) and sodium hyaluronate 15 mg/mL mixed with lidocaine 0.5%, lidocaine 1.0%, and lidocaine 1.65%. The solutions were dyed with fluorescein to enhance visualization. After the capsular bag was filled with 1 of the solutions, a posterior chamber intraocular lens was implanted. The solution was then aspirated using an automated I/A device set at 250 mm Hg of aspiration. The time required to remove most and then all the material was recorded.

RESULTS

The mean time required for removal of most of the Ophthalin Plus, viscoanesthesia 0.5%, viscoanesthesia 1%, and viscoanesthesia 1.65% solutions was 8.7 seconds +/- 2.1 (SD), 7.7 +/- 1.1 seconds, 9.7 +/- 0.6 seconds, and 6.3 +/- 1.5 seconds, respectively (P =.1). The mean time to remove all the solutions was 21.3 +/- 3.2 seconds, 19.7 +/- 2.5 seconds, 18.3 +/- 3.2 seconds, and 15.7 +/- 2.1 seconds, respectively (P =.166). No subjective difference in viscosity or consistency was found among the solutions.

CONCLUSIONS

The addition of lidocaine to the OVD solution did not significantly alter the viscosity or consistency of the solution or change its removal time from the capsular bag.

Corneal endothelial cell protection during phacoemulsification: low- versus high-molecular-weight sodium hyaluronate

PURPOSE

To compare the efficacy of low- and high-molecular-weight sodium hyaluronate in protecting corneal endothelial cells during phacoemulsification.

SETTING

Miyata Eye Hospital, Miyakonojo, Miyazaki, Japan.

METHODS

One hundred forty-nine eyes of 136 cataract patients were randomly assigned to have cataract surgery using sodium hyaluronate 1% with a low molecular weight (0.6 to 1.2 million d, Opegan) or sodium hyaluronate 1% with a high molecular weight (4 million d, Healon) during phacoemulsification. Each group was divided into 2 subgroups depending on the amount of ultrasound (% min) used during phacoemulsification, which was defined as the mean phacoemulsification energy (%) multiplied by phacoemulsification time (minutes). Corneal endothelial cell density was examined preoperatively and 3 months after surgery. The rate of cell loss was compared between the subgroups in the Opegan group and the Healon group.

RESULTS

In the subgroups with ultrasound of 50% min or less, the mean rate of endothelial cell loss 3 months after surgery was 3.2% +/- 4.1% (SD) in the Opegan group and 5.9% +/- 5.3% in the Healon group (P =.0214). In the subgroups with ultrasound over 50% min, the mean rate of endothelial cell loss 3 months after surgery was 7.5% +/- 10.6% in the Opegan group and 14.8 +/- 9.0% in the Healon group (P =.0029).

CONCLUSIONS

The results suggest that Opegan is more effective than Healon in protecting corneal endothelial cells during phacoemulsification regardless of the amount of ultrasound energy used.

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.

Posterior capsule folds and removal of ophthalmic viscosurgical devices

PURPOSE

To evaluate the relationship between posterior capsule folds and an ophthalmic viscosurgical device (OVD) during cataract surgery.

SETTING

Parkland Memorial Hospital, Dallas, Texas, USA.

METHODS

A prospective observational study of 91 consecutive uneventful cataract extractions by phacoemulsification was performed. The presence or absence of posterior capsule folds was noted immediately after intraocular lens (IOL) implantation and after OVD removal.

RESULTS

Posterior capsule folds were present in 21 of 49 cases (43%) with an MA60BM lens (Alcon Laboratories) and in 1 of 42 cases (2%) with an SA30AL lens. In the MA60BM group with folds, the folds were noted before OVD removal in 14 cases and after OVD removal in 16 cases. There was no significant difference in age, sex, axial length, horizontal corneal diameter, or IOL power between groups with and without posterior capsule folds.

CONCLUSIONS

The presence of posterior capsule folds does not reliably signify the complete removal of OVDs.

Healon5: comparison of 2 removal techniques

PURPOSE

To evaluate the effect on intraocular pressure (IOP) of the rock 'n roll and behind-the-lens techniques of removing Healon(R)5 (sodium hyaluronate 2.3%).

SETTING

St. Erik's Eye Hospital, Stockholm, Sweden.

METHODS

In a prospective randomized study of 159 patients, 2 techniques to remove Healon5--rock 'n roll and behind-the-lens--were compared during cataract surgery. Cataract surgery included identical phacoemulsification performed by 1 surgeon and implantation of a silicone intraocular lens (IOL) in the capsular bag. The removal time of Healon5 was recorded. The IOP was measured preoperatively and 5 and 24 hours postoperatively.

RESULTS

The mean IOP before surgery was 15.7 mm Hg +/- 2.8 (SD) in the rock 'n roll group and 15.9 +/- 2.7 mm Hg in the behind-the-lens group. Five hours postoperatively, the mean IOP was 25.6 +/- 10.4 mm Hg and 22.4 +/- 7.6 mm Hg, respectively; the difference between the groups was statistically significant. By 24 hours postoperatively, the mean IOP was at preoperative levels in both groups. The mean removal time of Healon5 was 50 seconds in the rock 'n roll group and 39 seconds in the behind-the-lens group; the difference between the groups was statistically significant.

CONCLUSIONS

Results indicate that the behind-the-lens technique for removing Healon5 is quicker and safer than the rock 'n roll technique.