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

Abstract

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.

Effects of Combinations of Ophthalmic Viscosurgical Devices and Suction Flow Rates on the Corneal Endothelial Cell Damage Incurred during Phacoemulsification

“…In ophthalmic surgery, various methods for assessing surgical invasion have been reported [23,24]. We observed the behavior of OVDs during phacoemulsification using the "slit side view" method and fluorescein-stained OVDs, which enabled viewing of the movement of OVDs intraoperatively and the fluid dynamics in the anterior chamber [25]. With the soft-shell technique, the dispersive OVD formed an uneven layer on the surface of the corneal endothelium, where it remained during the phacoemulsification procedure.…”

“…With the soft-shell technique, the dispersive OVD formed an uneven layer on the surface of the corneal endothelium, where it remained during the phacoemulsification procedure. In contrast, the viscoadaptive OVD remained inside the anterior chamber as a lump, and the irrigation solution often flowed between the corneal endothelium and the OVD, leading to the detachment of the OVD [ 25 ]. These mechanisms may have contributed to the larger ECD reduction rate seen in the V group when compared with the S group at 1 week postoperatively.…”

Evaluation of the Utility of Capsular Stabilization Devices in a Zonular Fiber Defect Model with the Slit Side View System

“…The extracted porcine eyes used in this experiment were obtained from a local abattoir. Each porcine eye was positioned on an eyeball fixing stand that was attached to a slit lamp microscope (Takagi, Nagano-ken, Japan) [ 15 ]. We, then, inserted an OVD via the side port and created a 2.4 mm incised corneal wound.…”

“…We previously reported the usefulness of the slit side view (SSV), which is a method to observe the anterior chamber in a cross-sectional view [ 15 ]. The SSV allows observation of the movement of ophthalmic viscosurgical devices (OVD) and changes in the anterior chamber depth in accordance with the machine settings during surgery [ 15 ]. The purpose of the current study was to evaluate the usefulness of capsular stabilization devices in Zinn's zonular fiber defect model with SSV.…”

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

“…[8][9][10] Ophthalmic researchers have concluded that retention durability is one of the important properties of OVDs during ocular surgery not only in the intraocular space but also on the ocular surface. [9][10][11][12][13] Previously, we have demonstrated that OVD products have their own rheological properties, even if their product specifications are the same value. 14,15) We have considered that rheological properties, which are not estimated so far, might also influence the retention durability of OVDs not only on the corneal surface but also in the eye.…”