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

The applications of viscoelastic agents in vitreoretinal surgery

The introduction of viscoelastics in human ocular surgery dates back to 1972.Subsequntly, several substances were proposed as adjuvants, particularly for cataract surgery; however, the rheologic properties of ophthalmic viscosurgical devices (OVDs), such as viscosity, pseudoplasticity, and coatability led to their employment also in vitreoretinal surgery. OVDs can be used to separate tissues and create space, to break adhesions, to allow space for surgical manipulation, and to contain hemorrhage by dampening capillary oozing. We focus on the principles and clinical results of several viscosurgery techniques, such as viscodissection and viscodelamination for the management of proliferative vitreoretinopathy and diabetic retinopathy and suprachoroidal buckling for primary retinal detachment. Furthermore, we analyze the techniques in which OVDs served as adjuvants in macular hole surgery, particularly in the handling of the internal limiting membrane, and as volumetric substances against hypotony. Finally, we analyze recent perspectives on vitreous humor biochemical features. Preclinical research led to the belief that hyaluronic acid-based hydrogels could become ideal vitreous substitutes, thanks to their viscoelasticity, porosity, optical properties, and biocompatibility; however, although promising, long-term toxicity issues have limited studies on human subjects.

Evaluating the Protective Effects of a Dispersive Ophthalmic Viscosurgical Device Versus Balanced Salt Solution on the Cornea During Cataract Surgery

OBJECTIVES

To compare intraoperative and postoperative effects of applying a viscosurgical device versus balanced salt solution (BSS) during cataract surgery.

METHODS

Single-center retrospective case-control pilot study. Reviewed 27 patients who received Viscoat (Alcon Laboratories, Inc. Fort Worth, TX) or BSS on the cornea during uncomplicated cataract surgery. Surgeries were analyzed for time when the microscope light reflection was indistinct on the cornea while instruments were in the eye. Postoperative data included patient pain ratings, National Eye Institute score, and Ocular Surface Disease Index (OSDI) scores.

RESULTS

Compared with BSS, Viscoat application resulted in a significant increase in time with a clear light reflex during surgery ( P <0.001). With BSS, average time without a clear light reflex while instruments were in the eye was 82.69±50.14 sec, or 17.56%±12.00% of the surgery, compared with 0% with Viscoat. There was no significant difference in postoperative pain and National Eye Institute score between groups. However, OSDI score two about grittiness was significantly lower with Viscoat application ( P =0.01) and approaching significance for OSDI score three, about painful or sore eyes ( P =0.09).

CONCLUSIONS

Viscoat provided greater optical clarity during surgery with a single application and was associated with less sensation of grittiness compared with BSS.

Injectable Fluorescent Bottlebrush Polymers for Interventional Procedures and Biomedical Imaging

Injectable biomaterials play a vital role in modern medicine, offering tailored functionalities for diverse therapeutic and diagnostic applications. In ophthalmology, for instance, viscoelastic materials are crucial for procedures such as cataract surgery but often leave residues, increasing postoperative risks. This study introduces injectable fluorescent viscoelastics (FluoVs) synthesized via one-step controlled radical copolymerization of oligo(ethylene glycol) acrylate and fluorescein acrylate. These bottlebrush-shaped polymers exhibit enhanced fluorescence intensity for improved traceability and facile removal postsurgery. To prevent aggregation, charged terpolymers were synthesized, ensuring intra- and intermolecular electrostatic repulsion. Dynamic light scattering and energy-conserved dissipative particle dynamics simulations revealed how the fluorescein content and monomer sequence affect the hydrodynamic size of these copolymers. Biocompatibility assessments showed that FluoVs maintained cell viability comparable to commercial hydroxypropyl methylcellulose and nonfluorescent poly(oligo(ethylene glycol) acrylate) controls. The FluoVs combine high fluorescence intensity, low viscosity, and excellent biocompatibility, offering intraoperative traceability and significant advancements for ocular and bioimaging applications.

Viscocohesive hyaluronan gel enhances stability of intravital multiphoton imaging with subcellular resolution

Multiphoton microscopy (MPM) has become a preferred technique for intravital imaging deep in living tissues with subcellular detail, where resolution and working depths are typically optimized utilizing high numerical aperture, water-immersion objectives with long focusing distances. However, this approach requires the maintenance of water between the specimen and the objective lens, which can be challenging or impossible for many intravital preparations with complex tissues and spatial arrangements. We introduce the novel use of cohesive hyaluronan gel (HG) as an immersion medium that can be used in place of water within existing optical setups to enable multiphoton imaging with equivalent quality and far superior stability. We characterize and compare imaging performance, longevity, and feasibility of preparations in various configurations. This combination of HG with MPM is highly accessible and opens the doors to new intravital imaging applications.

Impact of temperature on ophthalmic viscosurgical devices and clinical implications: a pilot study

PURPOSE

To evaluate how temperature affects the rheology of common ophthalmic viscosurgical devices (OVDs) and clinical implications.

SETTING

Tennent Institute of Ophthalmology, Glasgow, with Department of Mechanical and Aerospace Engineering, and Advanced Materials Research Laboratory, University of Strathclyde, Glasgow, United Kingdom.

DESIGN

Laboratory pilot study.

METHODS

The viscous and elastic responses of 3 OVDs (Eyefill-SC/Eyefill-C/Eyefill-HD) were measured using rotational and extensional rheometers at clinically relevant temperatures (5°C, 25°C, 37°C). Thermal properties were evaluated using differential scanning calorimetry and laser-flash analysis.

RESULTS

The OVDs tested exhibited viscoelastic properties and shear-thinning behavior. Apparent viscosities and relaxation time were higher at lower temperatures. The Eyefill-C and Eyefill-SC exhibited predominantly viscous character at low frequencies with a transition to predominantly elastic behavior at high frequencies. An increase in temperature led to a decrease in relaxation time under shear and extension. At low frequencies, Eyefill-C and Eyefill-SC moduli increase with decreasing temperatures. Eyefill-HD at 25°C and 37°C displays 2 crossover points, with the storage modulus dominating at low and high frequencies indicating a predominantly elastic behavior. Thermal property analysis revealed Eyefill-C had the lowest thermal conductivity.

CONCLUSIONS

This pilot study confirms our clinical experience that OVD properties are affected by low temperatures, with increased viscosities at low shear rates and higher relaxation times. Cold OVD can cause greater resistance to initiation of intraocular lens (IOL) injection system forces (compared with warmer OVD). Excessively forced injection using cold OVD could contribute to inadvertent cannula detachment if incorrectly assembled, or uncontrolled IOL release leading to avoidable injury.

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.

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Intraocular pressure before and after capsulorhexis using two viscoelastic substances and two surgical approaches in enucleated porcine eyes

AIM

To investigate the influence of ophthalmic viscoelastic devices (OVDs) and different surgical approaches on the intraocular pressure (IOP) before and after creation of the curvilinear circular capsulorhexis (CCC) as a measure for anterior chamber stability during this maneuver.

METHODS

Prospective experimental WetLab study carried out on enucleated porcine eyes. IOP was measured before and after CCC with the iCare Rebound tonometer (iCare ic200; iCare Finland Oy, Vantaa, Finland). The OVDs used were a cohesive one [Z-Hyalin, Carl Zeiss Meditec AG, Germany; hyaluronic acid (HA)] and a dispersive [Z-Celcoat, Carl Zeiss Meditec AG, Germany; hydroxy propylmethylcellulosis (HPMC)]. The CCC was created using Utrata forceps or 23 g microforceps in different combinations with the OVDs.

RESULTS

Using the Utrata forceps the IOP dropped from 63.65±6.44 to 11.25±3.63 mm Hg during the CCC. The use of different OVDs made no difference. Using the 23 g microforceps the IOP dropped from 65.35±8.15 to 36.55±6.09 mm Hg. The difference between IOP drop using either Utrata forceps or 23 g microforceps was highly significant regardless of the OVD used.

CONCLUSION

Using the sideport for the creation of the capsulorhexis leads to a lesser drop in IOP during this maneuver compared to the main incision in enucleated porcine eyes. The use of different OVD has no significant influence on IOP drop.

Enhancing Inverted Internal Limiting Membrane Flap Stability in Macular Hole Retinal Detachment by the "Viscoelastic Agent Pool" Technique

PURPOSE

To evaluate the surgical, anatomical, and functional results of "viscoelastic agent pool" technique-assisted stability of inverted internal limiting membrane flap in macular hole retinal detachment.

METHODS

The innovative surgical technique was performed on 10 patients with macular hole retinal detachment. The primary outcomes included best-corrected visual acuity after surgery, rate of closure of macular hole, retinal reattachment, and occurrence of complications.

RESULTS

The mean age of the individuals was 67.70 ± 8.75 (range, 55-84) years; mean axial length, 29.34 ± 1.53 (range, 27.10-30.93) mm; mean corrected MH diameter, 685.30± 345.65 (range, 172-1,325) µ m; and average follow-up period, 6.01 ± 1.71 (range, 3.10-8.4) months. In 6 eyes (60%), the postoperative best-corrected visual acuity showed improvement. All patients had macular hole closure, and the retinal reattachment rate was 100%. No postoperative complications were noted.

CONCLUSION

The "viscoelastic agent pool" technique, an innovative surgical approach designed to enhance the stability of the internal limiting membrane flap, serves as an effective adjunctive procedure for the inverted internal limiting membrane flap technique. It presents a viable option for patients with macular hole retinal detachment.

Air bubble guide for adequacy of ophthalmic viscosurgical device during phacoemulsification

Phacoemulsification in hard cataracts is a challenge. The use of dispersive ophthalmic viscosurgical devices (OVDs) to protect the endothelium is a routine step in such scenarios. However, as OVD is transparent, it is difficult to spot within the anterior chamber. Therefore, surgeons may not be aware when the OVD coating of the endothelium disappears during surgery. Consequently, there may be too frequent OVD injections, resulting in a waste of resources. On the contrary, the surgeon may fail to inject OVD at an appropriate time, leading to greater endothelial damage. We propose a novel technique of using an air bubble as a guide that helps in identifying the time when OVD disappears from the anterior chamber, thereby suggesting the surgeon to reinject before proceeding further.

Preoperative Evaluation of White Cataracts with the Pentacam

PURPOSE

To evaluate the use of the Pentacam to analyse the presence or absence of fluid pockets under the anterior capsule and their significance in terms of surgical management and prevention of complications.

SETTINGS

Abant İzzet Baysal University Hospital, Bolu, Turkey DESIGN: Randomized, masked, prospective design METHODS: 60 patients with mature cataracts underwent standard phacoemulsification (Phaco) and intraocular lens (IOL) implantation. Patients were divided into 3 groups. Group 1 underwent Phaco+IOL implantation without imaging by Pentacam. Group 2 had fluid detected in Pentacam imaging before the operation and underwent Phaco+IOL implantation with Brazilian method. Group 3 had no fluid detected in Pentacam imaging before the operation and underwent standart Phaco+IOL implantation operation.

RESULTS

When the complication rates of 3 different groups were examined separately, they were found to be 15 % in group 1; 5 % in group 2 and 5 % in group 3, respectively. When compared in pairs as Group 1-2, 1-3, and 2-3, respectively (p < 0.01), (p < 0.01), (p > 0.05). The nuclear density of Group 2 and Group 3 was measured, resulting in 30.2 % and 29.6 %, respectively (P = 0.614). Lens thickness, patients with fluid (+) had a thickness of 5.35 mm, while patients with fluid (-) had a thickness of 3.96 mm (p < 0.05).

CONCLUSION

Patients who are not imaged with pentacam before surgery experience more complications than other groups because the presence of fluid is unknown. Central lens thickness was higher in patients with fluid, and there was no significant difference in nuclear density between the groups with and without fluid. Pentacam can show the presence of supcapsular fluid and we recommend that imaging tools be more widely used in cataract surgery. We think that this will enable surgeons to make a more accurate surgical planning and reduce the risk of complications.

Viscoelastics Enable Dissection of Anterior Closed Funnels in Proliferative Vitreoretinopathy: A Retrospective Case Series

Introduction

The present study aimed to describe a case series of patients in which a cohesive ophthalmic viscous device (OVD) was used to viscodissect and posteriorly displace the retina in cases of total retinal detachment complicated by proliferative vitreoretinopathy, operated with minimally invasive pars plana vitrectomy.

Case Presentations

Three patients with a mean age of 67 years were included in the present study. One eye was aphakic, while the others were pseudophakic. OVD injection was performed through the limbus in the aphakic eye and via pars plana in the pseudophakic eyes. In all cases, the OVD injection led to a posterior displacement of the detached retina with a smooth dissection. No complications related to the surgery were observed. At the last follow-up visit, the retina was attached in all cases, with an improvement in visual acuity.

Conclusion

To conclude, the injection of a cohesive OVD anterior to the detached retina allowed to posteriorize and viscodissect to some extent the retina, facilitating the implant of trocars.

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

AIM

To report the clinical prognosis and pathological findings of accidental lens vacuolar changes in eyes with intraoperative exposure to a dispersive ophthalmic viscosurgical device (OVD).

METHODS

Two patients who developed transient lens vacuolar changes during uneventful persistent pupillary membrane (PPM) removal surgery were presented and followed up. This event was speculated to be associated with an intraoperative dispersive OVD DisCoVisc (hyaluronic acid 1.6%-chondroitin sulfate 4.0%) exposure. Then, to provide the pathological basis for our speculation, another four cataract patients were randomly exposed to different OVDs, and their anterior lens capsules were investigated with transmission electron microscopy (TEM).

RESULTS

After months, the subcapsular vacuoles in both PPM cases were gradually disappeared without visual deterioration. For the cataract patients, similar lens changes were observed intraoperatively in those exposed to a dispersive DisCoVisc but not a cohesive OVD IVIZ (sodium hyaluronate gel 1.0%). In addition, marked ultrastructural changes, including chromatin condensation, extensive cytoplasmic vacuoles, and obvious intercellular space between lens epithelial cells in the anterior lens capsules of all eyes exposed to DisCoVisc, were observed by TEM.

CONCLUSION

The lens vacuolar changes may be associated with a dispersive OVD exposure. Therefore, it is not preferable to use dispersive OVDs in patients with transparent lenses or without the intention of lens extraction. In addition, close follow-ups instead of immediate lens extraction are recommended for the occurrence of similar lens lesions.

Forward Light Scattering of First to Third Generation Vitreous Body Replacement Hydrogels after Surgical Application Compared to Conventional Silicone Oils and Vitreous Body

To treat certain vitreoretinal diseases, the vitreous body, a hydrogel composed of mostly collagen and hyaluronic acid, must be removed. After vitrectomy surgery, the vitreous cavity is filled with an endotamponade. Previously, pre-clinical hydrogel-based vitreous body substitutes either made from uncrosslinked monomers (1st generation), preformed crosslinked polymers (2nd generation), or in situ gelating polymers (3rd generation) have been developed. Forward light scattering is a measure of Stray light induced by optical media, when increased, causing visual disturbance and glare. During pinhole surgery, the hydrogels are injected into the vitreous cavity through a small 23G-cannula. The aim of this study was to assess if and to what extent forward light scattering is induced by vitreous body replacement hydrogels and if Stray light differs between different generations of vitreous body hydrogel replacements due to the different gelation mechanisms and fragmentation during injection. A modified C-Quant setup was used to objectively determine forward light scattering. In this study, we found that the 1st and 3rd generation vitreous body replacements show very low stray light levels even after injection (2.8 +/- 0.4 deg2/sr and 0.2 +/- 0.2 deg2/sr, respectively) as gel fragmentation and generation of interfaces is circumvented. The 2nd generation preformed hydrogels showed a permanent increase in stray light after injection that will most likely lead to symptoms such as glare when used in patients (11.9 +/- 0.9 deg2/sr). Stray light of the 2nd generation hydrogels was 3- and 2-fold increased compared to juvenile and aged vitreous bodies, respectively. In conclusion, this significant downside in the forward light scattering of the 2nd generation hydrogels should be kept in mind when developing vitreous body replacement strategies, as any source of stray light should be minimized in patients with retinal comorbidities.

Physical Characteristics, Clinical Application, and Side Effects of Viscoelastics in Ophthalmology

Purpose

To explain the physical properties of ophthalmic viscoelastic devices (OVDs), covering their structural units, optimal features, existing viscoelastic materials, clinical applications, and potential side effects.

Methods

This is a narrative review on the OVDs. A literature review was conducted in PubMed, Google Scholar, and Scopus databases. Studies that investigated physical characteristics, clinical applications, OVD commercial products, and their complications were included.

Results

We included 42 articles from 2010 and discussed physical characteristics, properties of a desirable OVD, structural units of common OVDs, OVD commercial products, clinical applications, and also complications of OVDs.

Conclusions

Today, viscoelastics hold a distinct and crucial role in intraocular surgery due to their remarkable properties. These materials safeguard the endothelium and epithelium, uphold anterior chamber depth, manage intraocular bleeding, ease tissue handling, and aid intraocular lens placement. Currently, the American market features 12 prevalent viscoelastic types, including 7 sodium hyaluronate derivatives (Healon, Healon-Greater Viscosity, Healon-5, Amvisc, Amvisc Plus, Advanced Medical Optics Vitrax, and Provisc), 2 hydroxypropyl methylcellulose 2% derivatives (OcuCoat and Cellugel), and 3 combinations of sodium hyaluronate and chondroitin sulfate (Viscoat, DisCoVisc, and DuoVisc). Despite the introduction of new viscoelastic materials annually, no single material encompasses all desired properties. Surgeons must select and employ suitable viscoelastics based on surgical conditions and patient requirements. Advancements in material development and understanding of physical properties and clinical applications continue to refine viscoelastic selection.

Viscoelasticity of Liposomal Dispersions

Janus-faced viscoelastic gelling agents-possessing both elastic and viscous characteristics-provide materials with unique features including strengthening ability under stress and a liquid-like character with lower viscosities under relaxed conditions. The mentioned multifunctional character is manifested in several body fluids such as human tears, synovial liquids, skin tissues and mucins, endowing the fluids with a special physical resistance property that can be analyzed by dynamic oscillatory rheology. Therefore, during the development of pharmaceutical or cosmetical formulations-with the intention of mimicking the physiological conditions-rheological studies on viscoelasticity are strongly recommended and the selection of viscoelastic preparations is highlighted. In our study, we aimed to determine the viscoelasticity of various liposomal dispersions. We intended to evaluate the impact of lipid concentration, the presence of cholesterol or 1,2-distearoyl-sn-glycero-3-phosphocholine (DSPC) and the gelling agents polyvinyl alcohol (PVA) and hydroxyethylcellulose (HEC) on the viscoelasticity of vesicular systems. Furthermore, the effect of two model drugs (phenyl salicylate and caffeine) on the viscoelastic behavior of liposomal systems was studied. Based on our measurements, the oscillation rheological properties of the liposomal formulations were influenced both by the composition and the lamellarity/size of the lipid vesicles.

Safety and effectiveness comparison of a new cohesive ophthalmic viscosurgical device

PURPOSE

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

SETTING

22 sites in the United States.

DESIGN

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Corneal Outcomes Following Cataract Surgery Using Ophthalmic Viscosurgical Devices Composed of Chondroitin Sulfate-Hyaluronic Acid: A Systematic Review and Meta-Analysis

Background

Ophthalmic viscosurgical devices (OVDs) are commonly used during cataract surgery to protect the corneal endothelium. A systematic literature review and meta-analysis were conducted to assess the clinical evidence of OVDs composed of chondroitin sulfate-hyaluronic acid (CS-HA) versus other OVDs in maintaining endothelial cell density (ECD) and corneal thickness (CT).

Methods

MEDLINE and EMBASE databases were searched from 2000 to 2020. Randomized controlled trials (RCTs, N ≥ 20 per group) comparing an OVD containing CS-HA (ie, VISCOAT^®, DuoVisc^® or DisCoVisc^®) to any other OVD were included. The identified comparators were limited to the OVDs found in the literature, which included those composed of HA-only or hydroxypropyl methylcellulose (HPMC). Outcomes of focus included changes in ECD (baseline to 3 months) and CT (baseline to 24 hours). Meta-analyses were performed using R software, to assess mean differences (MD) in ECD and CT change between CS-HA OVDs and HA-only or HPMC OVDs.

Results

A total of 966 abstracts were screened, and data were extracted from 12 RCTs. Meta-analyses using a random-effects model revealed significantly lower percent (%) decrease in ECD for CS-HA OVDs compared to both HA-only (MD: -4.10%; 95% CI: -5.81 to -2.40; p < 0.0001; 9 studies) and HPMC (MD: -6.47%; 95% CI: -10.41 to -2.52; p = 0.001; 2 studies) products. Similarly, % CT increase was significantly lower with CS-HA than with HA-only OVDs (MD: -3.22%; 95% CI: -6.24% to -0.20%; p = 0.04; 4 studies). However, there were no significant differences when comparing % CT change between CS-HA and HPMC OVDs (MD: 2.65%; 95% CI: -0.43% to 0.95%; p = 0.4; 2 studies).

Conclusion

CS-HA OVDs lead to less postoperative loss of endothelial cells and may better protect corneal endothelium during cataract surgery, relative to other OVDs. Future randomized studies may be needed to solidify these findings.

Ophthalmic viscoelastics commonly used in cataract surgery: A microbiota investigation

PURPOSE

To survey commonly used, sterile ophthalmic viscoelastic materials used during routine cataract surgery for the presence of bacterial DNA and/or viable bacteria and endotoxin quantification.

METHODS

Samples from three different ophthalmic viscoelastic manufacturers and three different production lots per manufacturer were collected for 16 S ribosomal ribonucleic acid (rRNA) sequencing and conventional aerobic and capnophilic bacterial culture. Other samples of viscoelastic material from the same three manufacturers were collected for endotoxin quantification using a commercially available Limulus amebocyte lysate (LAL) assay. Statistical analysis was performed using Sigma Plot 14.0, and R v4.0.2.0. Differences (p ≤ .05) between sample collection sites in total DNA concentration, microbial richness, mean intra-group distances, and endotoxin quantification alongside reagent controls were evaluated.

RESULTS

Culture yielded two isolates, identified as Staphylococcus epidermidis and Bacillus megaterium. 16 S rRNA sequencing revealed no differences between brands in richness or overall composition. The most common bacterial DNA detected across all brands was Staphylococcus sp., Cutibacterium sp., Flavobacterium sp., and Lactobacillus sp. A significant difference was found between the median endotoxin concentration between Anvision and Hyvisc® viscoelastic (Anvision: 0.171 EU/mL, Hyvisc®: 0.03 EU/mL; p < .001).

CONCLUSIONS

No brand-specific differences in bacterial DNA were detected in the viscoelastic materials. Staphylococcus, Cutibacterium, Flavobacterium, and Lactobacillus were the dominant contributors to the bacterial DNA detected. Although Anvision viscoelastic samples contained significantly more endotoxin than Hyvisc® viscoelastic samples, endotoxin concentrations were below the FDA limit of 0.2 EU/mL for both manufacturers. These data further the understanding of inflammatory outcomes following cataract surgery.

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.

Advances in biomaterials as a retinal patch for the repair of rhegmatogenous retinal detachment

Rhegmatogenous retinal detachment (RRD) is the most common retinological emergency that can cause blindness without surgical treatment. RRD occurs when liquefied vitreous accumulates between the neurosensory retina and the retinal pigment epithelium via retinal breaks, which are caused by the separation of the vitreous from the retina with aging. Currently, the main treatment option is pars plana vitrectomy, which involves surgical removal of the vitreous and laser photocoagulation around retinal breaks to generate firm chorioretinal adhesion, as well as subsequent filling of the vitreous cavity with long-lasting substitutes (expansile gas or silocone oil) to prevent the connection between the subretinal space and the vitreous cavity via the breaks before the chorioretinal adhesion firm enough. However, the postoperative face-down position and the not very satisfactory first retinal reattachment rate place a heavy burden on patients. With the development of technology and materials engineering, researchers have developed biomaterials that can be used as a retinal patch to seal retinal breaks and prevent the connection of subretinal space and vitreous cavity via breaks, thus replacing the long-lasting vitreous substitutes and eliminating the postoperative face-down position. Preclinical studies have demonstrated that biomaterial sealants have enough biocompatibility and efficacy in the in vitro and in vivo experiments. Some sealants have been used in clinical trials on a small scale, and the results indicate promising application prospects of the biomaterial sealants as retinal patches in the repair of RRD. Herein, we review the recent advances in biomaterials as retinal patches for the repair of RRD, focusing on the biomaterial categories, methods, and procedures for sealing retinal breaks, as well as their biocompatibility and efficacy, current limitations, and development perspectives.

Comparative evaluation of the results of phacoemulsification using domestic and foreign viscoelastics

BACKGROUND: Phacoemulsification, being the safest technique, is the golden standard of cataract surgery worldwide. However, as any surgery, it is accompanied by inevitable damage to intraocular structures. The most prevalent among them is the loss of corneal endothelial cells. In order to prevent these complications, various viscoelastics with particular features and characteristics are widely used. AIM: To compare the anatomical and functional state of ocular structures after standard phacoemulsification with monofocal posterior chamber intraocular lens (IOL) implantation using domestic (Kogevisc and Adgevisc) and foreign (Viscoat and Amvisc Plus) viscoelastics. MATERIALS AND METHODS: 60 cataract patients (60 eyes) were included in the clinical study, which were divided into two equal groups. In the first group (30 patients, 30 eyes), Adgevisc and Kogevisc (Solofarm, Russia) were used during the procedure. The mean age of the patients was 66 11 years. In the second group (30 patients, 30 eyes), Viscoat (Alcon) and Amvisc Plus (BauschLomb) were used. The mean age of the patients was 69.03 10.44 years. All patients underwent phacoemulsification with the implantation of the AcrySof IOL (model SA60AT, Alcon) according to the standard technique. Visual acuity, IOP level, CCT, corneal endothelial cell density were assessed. All studies were performed before surgery, the next day, 7 days and 1 month after surgery. RESULTS: In patients of the second group, on the 1st (p 0.05) and 7th day (p 0.01) after surgery, a statistically significant increase in IOP was revealed compared to the first group. The central cornea thickness in the early postoperative period was higher in patients of the second group, however, it was not statistically significant. The loss of corneal endothelial cells 1 month after surgery was 8.5 7.0% (p 0.01) in the first group and 6.6 6.4% in the second group (p 0.01). The mean value of endothelial cell loss in patients of the first group was higher, however, it was not statistically significant. The best corrected visual acuity in both groups at all stages of follow-up after surgery (days 1, 7 and 30) was comparable, there was no significant difference between the groups. CONCLUSIONS: The clinical efficacy of domestic adhesive and cohesive viscoelastics Adgevisc and Kogevisc (Solofarm, Russia) in phacoemulsification using the soft-shell technique is comparable to the foreign analogues Viscoat (Alcon) and Amvisc Plus (Bausch Lomb), which is confirmed by the absence of statistically significant differences in the studied parameters of the postoperative state of ocular structures and explained by their similar composition, molecular weight and viscosity.

Evaluation of the Rheological Properties, Preclinical Safety, and Clinical Effectiveness of a New Dispersive Ophthalmic Viscoelastic Device for Cataract Surgery

Purpose

To evaluate the rheological properties of the ophthalmic viscoelastic device (OVD) PRO-149, its preclinical safety, and its effectiveness when used during cataract surgery in patients with age-related cataract.

Material and Methods

Control (HEC) and test (PRO-149) OVDs were compared through rheological measures, by two preclinical safety studies in rabbits, and under normal-use conditions during cataract removal and lens implantation in a parallel randomized clinical trial.

Results

Rheological properties were determined. Preclinical studies did not find any evidence of safety issues or toxicity. In the clinical trial, 36 subjects were included. After 29 days, there were no statistically significant differences in mean percentage of endothelial cell count change or in the postoperative intraocular pressure between groups. There were no significant differences between OVDs for any safety parameter studied. Finally, PRO-149 showed a statistically significant improvement in surgeon rating for ease of use during extraction (p < 0.05).

Conclusion

PRO-149 is a dispersive OVD. The rabbit models did not find evidence of clinical alterations or toxicity. The results of the clinical study support that the two studied OVDs were clinically similar in terms of safety and effectiveness for cataract surgery.

Trial Registration

The trial is registered at Clinical Trials.gov at NCT04702802 (21–01-11).