Scheimpflug photography study of ophthalmic viscosurgical devices during simulated cataract surgery

A Novel Marking Technique for Descemet Membrane Endothelial Graft Using an Ophthalmic Viscoelastic Device

PURPOSE

To describe the viscoelastic marking technique, a novel marking technique of Descemet membrane endothelial keratoplasty (DMEK) grafts that enables usage of a single donor cornea for 2 surgeries-one that uses Descemet membrane and endothelium (DMEK) and the other using the stroma and Bowman layer.

METHODS

A retrospective case analysis was performed on 26 eyes of 26 consecutive patients who underwent DMEK using the "viscoelastic marking technique." In this novel technique, an ophthalmic viscoelastic device (Healon 5) is placed over the endothelial side. Descemet membrane is then folded in half over the ophthalmic viscoelastic device with the stromal side up, and the F mark is drawn on the stromal side of the folded Descemet membrane. Primary outcome was best spectacle-corrected visual acuity, and secondary outcomes included graft detachment and rebubble rate, graft failure, and endothelial cell density.

RESULTS

Mean best spectacle-corrected visual acuity improved significantly from 1.0 ± 0.7 logarithm of the minimum angle of resolution (LogMAR) before the surgery to 0.9 ± 0.7 LogMAR, 0.5 ± 0.6 LogMAR, 0.4 ± 0.2 LogMAR, and 0.4 ± 0.4 LogMAR at 1, 3, 6, and 12 months after surgery, respectively. Seven eyes (27%) had partial graft detachment that required air injection. Primary failure occurred in 3 eyes (11%). There were no free-floating donors or recognized inverted donors. The endothelial cell density loss at 12 months after surgery was a cell-loss rate of 38.3%.

CONCLUSIONS

The viscoelastic marking technique is a simple, approachable, and safe technique for marking DMEK grafts while preserving the anterior cornea for additional surgery.

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

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

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.

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.

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.

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.

Corneal edema and intraocular pressure after cataract surgery: randomized comparison of Healon5 and Amvisc Plus

PURPOSE

To compare the protective effect of Healon5 (sodium hyaluronate 2.3%) and Amvisc Plus (sodium hyaluronate 1.6%) against corneal edema and their association with postoperative intraocular pressure (IOP) spikes in patients having phacoemulsification and intraocular lens (IOL) implantation.

SETTING

Ophthalmology department of a general hospital.

METHODS

One hundred forty patients were randomly assigned to have surgery with Healon5 (n = 70) or Amvisc Plus (n = 70). One eye of each patient was analyzed. Data collected preoperatively included best corrected visual acuity (BCVA) and IOP. Central ultrasonic pachymetry was performed in all patients. The same ophthalmologist performed all surgeries. The IOP and central corneal thickness (CCT) were measured 1 and 4 days and 1 month after surgery. The BCVA was also assessed at 1 month.

RESULTS

There were no significant preoperative differences between the Healon5 and Amvisc Plus groups in sex, age, ocular pathology, BCVA, IOP, or CCT. Intraoperative variables were similar between groups, but it took significantly longer to remove the Healon5. Postoperatively, there were no differences between groups in the evolution of CCT or of IOP. Intraocular pressure spikes over 30 mm Hg were detected at 1 day in 7 patients in the Healon5 group and 2 patients in the Amvisc Plus group (10.0% versus 2.9%; P = .165).

CONCLUSIONS

Both OVDs were beneficial in a wide range of cataract patients. However, the results suggest a tendency toward a higher complication rate with Healon5.

Survey of ophthalmic viscosurgical devices

PURPOSE OF REVIEW

Cataract treatment is evolving, thanks to new phaco systems and innovative surgical techniques. Recent ophthalmic viscosurgical devices (OVDs) play an important role in the development of new approaches to surgery. Knowledge of the new techniques and advances in new OVDs is crucial to performing routine and complicated surgeries.

RECENT FINDINGS

Viscoadaptive substances have been introduced as a particular kind of OVD and are distinguished by high viscosity at a low flow rate and a tendency to fracture at higher flow rates, assuming pseudodispersive behavior. The ultimate soft shell technique emphasizes the rheology of viscoadaptive OVDs to perform phacoemulsification procedures, exploiting all the useful properties of these OVDs in terms of space maintenance and tissue protection. Recent studies have highlighted some new and interesting aspects of the use of OVDs. Current reports suggest that the association of lidocaine and OVD seems to be safe and useful in providing anesthesia during cataract surgery. Concern has been expressed in other studies regarding the presence of contaminants, such as endotoxins, which may be responsible for postoperative uveitis-like reactions. Finally, OVDs are widely known to protect the corneal endothelium during cataract surgery. Their role is also assuming relevance in vitreoretinal surgery.

SUMMARY

New OVDs and related techniques represent an advancement in cataract surgery.