Survey of ophthalmic viscosurgical devices

A Prospective, Randomized, Controlled Clinical Investigation Comparing the Efficacy and Safety of Sodium Hyaluronate-Based Ophthalmical Viscosurgical Devices FIDIAL PLUS and IAL®-F in Cataract Surgery

Purpose: To protect the corneal endothelium, various ophthalmical viscoelastic devices (OVDs) are used during cataract surgery. In this study, we compared two sodium hyaluronate-based OVD, the bacteria-derived FIDIAL PLUS OVD (test) with the animal-derived IAL®-F OVD (reference) during the surgical procedure. Methods: Fifty patients with bilateral cataract participated in the study: 50 eyes randomly received FIDIAL PLUS and 50 eyes received IAL®-F (ratio 1:1). Noninferior efficacy of FIDIAL PLUS compared with reference OVD (first objective) was evaluated using a paired t-test comparing the mean percent loss of corneal endothelial cells (CECs) with FIDIAL PLUS against the mean percent loss with IAL®-F. Corneal endothelial protection during cataract surgery with FIDIAL PLUS without significant (≥30 mmHg) postoperative intraocular pressure (IOP) increase (main secondary objective) was assessed using a repeated measures logistic model comparing the incidence of significant postoperative IOP elevation between the two groups. Safety, tolerability, and efficacy were also evaluated by assessing secondary endpoints before and after surgery. Results: FIDIAL PLUS showed a statistically noninferior efficacy compared with IAL®-F; there was no significant increase in IOP in either group or different trends of the secondary endpoints were observed between the OVD groups. The safety profile was similar in both OVD groups and no adverse device effects were reported. Conclusions: This study demonstrates the equivalent efficacy, tolerability, and safety of the bacteria-derived FIDIAL PLUS compared with the animal-derived IAL®-F, confirming the clinical value of this product.

Factors influencing aqueous flare after cataract surgery and its evaluation with laser flare photometry

Despite the refinement of modern cataract surgery, postoperative inflammation still constitutes a substantial amount of visual morbidity worldwide. A surrogate for intraocular inflammation and blood-aqueous barrier breakdown can be objectively quantified by Laser flare photometry (LFP). This review outlines the utility of LFP in assessing the assessment of post-cataract surgery inflammation. It highlights the impact of preoperative pathological states such as uveitis and diabetes, intraoperative techniques, including efficient phacoemulsification and direct comparisons between postoperative anti-inflammatory regimes. There is a large interobserver variation in the subjective flare measurement after cataract surgery and the continued use of LFP amongst other objective, noninvasive measurements of intraocular inflammation, particularly in the further development of cataract surgery, is recommended.

Corneal endothelium protection provided by ophthalmic viscosurgical devices during phacoemulsification: experimental study in rabbit eyes

PURPOSE

To compare the protection of the corneal endothelium provided by a cohesive and a dispersive ophthalmic viscosurgical device (OVD) against damage from torsional ultrasound and simulated lenticular debris during phacoemulsification.

SETTING

University setting, Salt Lake City, Utah.

DESIGN

Experimental study.

METHODS

15 New Zealand rabbits were included. After incision, each eye received cohesive or dispersive OVD (ProVisc or Viscoat). 10 1.0 mm beads were injected to simulate lenticular debris. The Intrepid Balanced tip (Centurion Ozil handpiece) was inserted into the anterior chamber, and 60% torsional ultrasound with 50 mL/min flow, 70 mm Hg intraocular pressure, and 600 mm Hg vacuum was applied (20 seconds). Cumulative dissipated energy (CDE) was noted. After euthanasia and enucleation, corneas were removed, stained with trypan blue/alizarin red, and photographed (5 ×400 magnification photos and 1 overview photograph from each cornea). ImageJ was used to evaluate cell damage and loss.

RESULTS

CDE was 4.70 ± 0.26 and 4.64 ± 0.10 in the cohesive and dispersive OVD groups, respectively ( P = .8647). The analysis of the ×400 photographs showed that the percentage of intact cells was statistically higher in the dispersive OVD group ( P = .0002), whereas the percentages of damaged and lost cells were statistically higher in the cohesive OVD group ( P = .0002 and .0059, respectively). Overview photographs revealed the presence of residual OVD on the endothelium, especially in the dispersive group.

CONCLUSIONS

In this experimental study using a rabbit model, the corneal endothelium protection provided by the dispersive OVD was superior to that provided by the cohesive OVD.

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.

Corneal endothelial damage in phacoemulsification using an anterior chamber maintainer compared with using an ophthalmic viscosurgical device

PURPOSE

To compare the effects of phacoemulsification surgery (PE) using an anterior chamber maintainer (ACM) and conventional PE using an ophthalmic viscosurgical device (OVD) on corneal endothelial cells.

SETTING

Department of Ophthalmology, Celal Bayar University, Manisa, Turkey.

DESIGN

Prospective randomized controlled trial.

METHODS

Eyes in the OVD group (n = 50) underwent conventional PE, whereas eyes in the ACM group (n = 50) underwent PE using an ACM. Endothelial cell density (ECD), coefficient of variation (CV), hexagonality (HEX), and noncontact central corneal thickness (CCT) measurements were performed by specular microscopy before and at 1 month, 3 months, and 6 months after PE.

RESULTS

This study included 100 eyes of 97 patients undergoing PE. The mean age was 64.7 ± 10.6 years in the OVD group, 64.0 ± 12.6 years in the ACM group (P > .05). The groups did not differ significantly in preoperative ECD, CV, HEX, and CCT or total PE time (P > .05 for all). ECD was significantly lower in the ACM group compared with the OVD group at postoperative 1 month, 3 months, and 6 months (P = .002, P = .002, and P = .001, respectively). Similarly, ECD loss compared with preoperative value was greater in the ACM group at all postoperative timepoints (P = .003, P = .001, and P = .001, respectively). CV increased and HEX decreased in both groups postoperatively (P > .05 for both). CCT showed a transient increase of less than 10 μm at postoperative 1 month in both groups (P = .296).

CONCLUSIONS

PE with ACM was associated with greater corneal ECD loss compared with conventional PE. ACM should not be used during PE in patients with limited corneal endothelial reserve.

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.

Pure phaco: phacoemulsification without ophthalmic viscosurgical devices

The ophthalmic viscosurgical device (OVD) is an essential part of modern phacoemulsification surgery. Many times, OVDs are blamed for intraocular pressure spikes, toxic anterior segment syndrome, and capsular bag distension syndrome. To avoid these complications, we developed a technique in which phacoemulsification can be done without using OVDs. The irrigating cannula, on a continuous irrigation mode, was introduced through a side port, and capsulorhexis and incision construction were performed under an irrigating balanced salt solution. No hydroprocedure was performed. Phacoemulsification was done by chopping technique. At the end of the procedure, the intraocular lens was implanted by wound assistance technique under a continuous irrigation mode.

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.

Femtosecond laser-assisted cataract surgery without OVD: a prospective intraindividual comparison

PURPOSE

To compare femtosecond laser-assisted cataract surgery without the use of ophthalmic viscosurgical device (OVD) with standard phacoemulsification using OVD.

METHODS

This was a prospective, randomized, single-center trial of 37 patients (74 eyes) diagnosed as having significant cataract in both eyes. Randomly, one eye underwent standard phacoemulsification with OVD (the OVD group); this group acted as controls. The other eye was treated with the femtosecond laser; the subsequent manual part of the procedure was performed without OVD (non-OVD group). Time of surgery, amount of fluid used during phacoemulsification, central corneal thickness, intraocular pressure, endothelial cell count, and visual acuity were documented over the 6-month follow-up.

RESULTS

There were no major complications and no significant difference in overall surgery time (non-OVD: 375 ± 81 seconds; OVD: 362 ± 43 seconds; P = .713) and in the quantity of fluid passing through the eye (non-OVD: 187 ± 35 mL; OVD: 186 ± 27 mL; P = .952) between groups. Endothelial cell loss after 6 months was not significantly different between groups (non-OVD: -2.4%; OVD: -2.7%; P = .880). Central corneal thickness was not different at 1 week postoperatively between groups (non-OVD: 575 ± 45 µm; OVD: 573 ± 46 µm; P = .820). Three patients in the OVD group and one patient in the non-OVD group experienced intraocular pressure greater than 25 mm Hg at 1 day postoperatively. There were no significant differences in corrected distance visual acuity between groups (logMAR non-OVD: 0.024; OVD: 0.038; P = .461).

CONCLUSIONS

Femtosecond laser-assisted treatment allows the cataract surgeon to perform phacoemulsification and intraocular lens implantation without the use of OVD at no additional risk to the corneal endothelium. Furthermore, there was a tendency toward fewer increases in intraocular pressure in patients treated with the femtosecond laser.

Capsulorhexis: Pearls and pitfalls

A critical step in phacoemulsification (as well as extracapsular cataract extraction) is making a window in anterior capsule wall (i.e. anterior capsulotomy). Continuous Curvilinear Capsulorhexis (CCC) has become recognized as the standard method of anterior capsulectomy. Techniques employed for CCC have undergone sustained evolution. The present review evaluates elementary principles of CCC. Management of CCC in the presence of small pupil and pseudoexfoliation syndrome is discussed. Main differences of pediatric CCC from its adult-style counterpart and finally several techniques of rescue of an extending capsulorhexis are also reviewed.

Management of Intraoperative Miosis during Pediatric Cataract Surgery using Healon 5

Purpose:

We describe a technique for achieving pupillary dilatation in order to manage and counteract intraoperative miosis during pediatric cataract surgery using viscoadaptive viscoelastic (sodium hyaluronate 2.3%).

Materials and Methods:

The technique of viscomydriasis was used in six eyes with pediatric cataracts with intraoperative pupillary miosis.

Results:

Pupillary dilatation was achieved and maintained in all eyes throughout cataract surgery. All the surgical steps including anterior and posterior capsulorrhexis and aspiration were performed successfully.

Conclusions:

Viscomydriasis is a simple and effective technique for the management of intraoperative pupillary miosis during cataract surgery in pediatric eyes.

Toxic anterior segment syndrome after foldable artiflex iris-fixated phakic intraocular lens implantation

Toxic anterior segment syndrome (TASS) developed in four cases after uneventful implantation of a foldable iris-fixated phakic intraocular lens (pIOL). Two cases occurred sequentially in one patient. The TASS subsided without complications in all cases after intensive topical steroid treatment. A multitude of possible causes is considered for the occurrence of these TASS cases. From the sterilization and cleaning of surgical instruments to the possibility of endotoxines in ophthalmic viscosurgical devices (OVD). These rare cases should alert the surgeon to the possibility of TASS after pIOL implantation.

Comparison of OVD and BSS for maintaining the anterior chamber during IOL implantation

PURPOSE

To compare surgical results between conventional intraocular lens (IOL) implantation using an ophthalmic viscosurgical device (OVD) and IOL implantation using a balanced salt solution (BSS) after irrigation/aspiration (I/A) of the lens cortex.

METHODS

A randomized prospective study was conducted on 62 patients who underwent cataract surgery. Following completion of conventional I/A of the lens cortex, we divided patients into two groups according to whether or not BSS was used. In group A (n = 31), the anterior chamber and the capsular bag were completely filled with an OVD before IOL implantation. On the other hand, in group B (n = 31), BSS was irrigated into the anterior chamber through a previous side port during IOL implantation. Surgical results were compared between the two groups.

RESULTS

In both groups, IOP peaked six hours after surgery. The occurrence of an IOP spike by postoperative day one was observed in six cases (6 / 31) in group A and in no cases (0 / 31) in group B, a difference that was statistically significant (p = 0.024). The values of endothelial cell density, central corneal thickness, anterior chamber inflammation, myopic shift, and posterior capsule opacification were not significantly different between the two groups.

CONCLUSIONS

Compared with the use of OVD for IOL implantation, use of BSS during IOL implantation resulted in reductions in postoperative IOP spike and OVD removal time.

Cataract surgery in Fuchs corneal dystrophy

PURPOSE OF REVIEW

Patients with decreased vision due to Fuchs corneal dystrophy and cataract can present with a number of challenges to determine the best surgical option for restoring sight. The ophthalmologist must first distinguish how much of the vision loss is due to the cataract versus the Fuchs corneal dystrophy (FCD) before determining the best surgical course, either cataract surgery alone or cataract surgery combined with full thickness or lamellar keratoplasty. This review will discuss the various techniques and clinical signs to ascertain the source of vision loss and how to use this clinical information to help guide the surgical decision making process in order to optimize the best possible outcome.

RECENT FINDINGS

Over the last several years, the technique of endothelial keratoplasty has evolved to become an important alternative in the treatment of FCD. Anticipating the correct intraocular lens power for a patient undergoing cataract surgery alone followed by Descemet stripping endothelial keratoplasty (DSEK) or combined cataract surgery with DSEK requires understanding the hyperopic shift that can occur with DSEK and incorporating this correction preoperatively in the intraocular lens power selection.

SUMMARY

New developments in the surgical treatment of Fuchs corneal dystrophy have greatly enhanced our ability to restore vision and reduce the dependence on contact lenses in this genetic disease.

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.

Comparison of corneal endothelial cell loss during phacoemulsification using continuous anterior chamber infusion versus those using ophthalmic viscosurgical device: randomized controlled trial

Aim

We conducted this study to evaluate and compare corneal endothelial cell loss between phacoemulsification with continuous anterior chamber infusion using anterior chamber maintainer (ACM) and phacoemulsification using ophthalmic viscosurgical device (OVD).

Materials and Methods

This was a prospective, randomized controlled trial. Fifty eyes of 47 patients of senile cataract undergoing phacoemulsification were included. Patients were randomly allocated into two groups of 25 eyes each. Cataract surgery was performed by phacoemulsification with anterior chamber (AC) continuous infusion with balanced salt solution (BSS) plus and ACM without OVD in Group A, and in Group B, phacoemulsification was performed using OVD with BSS plus. Corneal endothelial cell count and pachymetry were performed preoperatively and postoperatively on day 1, day 7, and day 30.

Results

The mean increase in pachymetry was 4.86%, 2.94%, and 1.94%, (Group A) and 5.95%, 3.94%, and 0.51%, (Group B) on first, seventh, and 30^th postoperative day respectively. The difference between the percentage increase in pachymetry between the two groups was not significant at day 1 (P = 0.441), day 7 (P = 0.298), and day 30 (P = 0.174) postoperatively. The density of endothelial cells decreased postoperatively (day 30) by 7.38% (Group A) and 7.47% (Group B) without any significant statistical difference (P = 0.983) between two groups.

Conclusion

Use of ACM for continuous AC infusion and omission of OVD during phacoemulsification did not cause significant difference in corneal swelling or endothelial cell loss in the immediate postoperative period up to one month.

Adjunct devices for managing challenging cases in cataract surgery: capsular staining and ophthalmic viscosurgical devices

PURPOSE OF REVIEW

Cataract surgeons should employ all reasonable technology to facilitate safe and consistent outcomes. Knowledge of adjunct devices to enhance visualization of the capsular bag and appropriate use of ophthalmic viscosurgical devices allow for enhanced protection of intraocular structures and reduced rates of complication.

RECENT FINDINGS

Trypan blue is US Food and Drug Administration-approved for facilitating visualization of the anterior capsule. Animal data demonstrate Brilliant Blue G to be an effective capsular stain with a superior safety profile. Healon5 is a safe viscosurgical device that is particularly useful in children, poorly dilating pupils, intraoperative floppy-iris syndrome, and intumescent cataracts. The viscoadaptivity of Healon5 enables its utility throughout the procedure of cataract extraction. The recent literature on capsular dyes and advances in ophthalmic viscosurgical technology is reviewed.

SUMMARY

Inadequate capsular visualization and poor tissue stabilization/protection increase the chance of discontinuous capsulorhexis, retained nuclear material, vitreous loss and corneal decompensation. Utilization of adjunctive tools in the setting of challenging cataract cases can significantly limit adverse intraoperative outcomes and result in reproducible surgical success.

Cataract surgery in Fuchs?? dystrophy

PURPOSE OF REVIEW

Corneal decompensation after cataract surgery can occur in patients with Fuchs' endothelial dystrophy. This paper reviews the pathogenesis of corneal edema in Fuchs' dystrophy, the preoperative and perioperative risk factors for corneal endothelial cell loss during cataract surgery, and indications for cataract surgery alone or cataract surgery combined with keratoplasty for patients with visually significant cataracts and Fuchs' dystrophy.

RECENT FINDINGS

Accelerated loss of corneal endothelial cells in Fuchs' dystrophy is multifactorial, with apoptosis and altered gene regulation of aquaporin proteins playing a role. Preoperative factors contributing to decreased endothelial cell count include age, sex, diabetes, a history of ocular trauma or inflammation, and contact lens wear. Intra-operative measures shown to protect endothelial cells include the use of the soft-shell viscoelastic technique for very dense cataracts, efficient cataract removal techniques (phaco-chop, use of oscillatory handpiece), and surgery by an experienced surgeon. A triple procedure should be performed with preoperative corneal epithelial decompensation and considered with preoperative pachymetry greater than 640 mum. Otherwise, it is reasonable to attempt cataract surgery alone with proper patient education.

SUMMARY

Fuchs' dystrophy is a progressive disorder. Cataract surgery in the setting of Fuchs' dystrophy can be performed successfully, especially when the surgeon is aware of the preoperative and intraoperative factors that affect the number of functioning endothelial cells. All patients should be aware of the progressive nature of this disease and the possibility of keratoplasty at some point in their lifetime.