Author: Christina Weng (United States)
Co-authors: Bernhard Pultar, Timo Jung, Reto Grueebler, Vara Wuyyuru
Purpose
Microsurgical forceps (MSF) are frequently utilized in vitreoretinal surgeries such as macular hole repair and epiretinal membrane peeling. Properties of MSFs such as physical dimensionality and the amount of force required to activate the tips may affect many aspects of forceps’ performance. While there are multiple types of MSF handles available, there have not been many studies evaluating them methodically. This study was designed to systematically compare the geometric attributes and activation forces of 20 commercially-available MSF handles of varying gauge sizes (23, 25, and 27).
Setting/Venue
20 different MSF handles from five different manufacturers (Alcon-Grieshaber, DORC, Vitreq, Synergetics, Katalyst) were evaluated using calipers that measure geometric dimensions and a standardized machine that measures activation forces. Each handle type was sampled five times and averaged for each measurement.
Methods
Geometric dimensions including length (mm), gauge length (mm), sleeve diameter (mm), minimum nose cone diameter (mm), maximum nose cone diameter (mm), maximum handle diameter (mm), tail diameter (mm), grip to nose distance (mm), and effective intraocular reach (mm) were measured using a caliper gauge. Gauge length was measured in both the closed and activated positions. Grip to nose distance was defined as the distance between the activation force application point and proximal tube/sleeve end. Effective intraocular reach was defined as the distance between the outer surface of the sclera and the distal tip of the activated instrument when fully inserted intraocularly. Instrument weights were measured using a scale. Activation forces were evaluated using a Universal Testing Machine for static application from Zwick. Activation force was defined as the amount of force required to fully close the tips of the MSF. The activation force parameters include activation force (N), activation travel (mm), and activation stiffness (N/mm).
Results
Descriptive statistics were calculated for all the parameters across the 20 tested MSFs. The weight ranged from 3.40-10.62 g (mean = 6.77 g). The length, gauge length, and effective intraocular reach ranged from 101.0-111.30 mm (mean = 108.42 mm), 26.60-35.19 mm (mean = 30.24 mm), and 25.48-33.57 mm (mean = 28.93 mm), respectively. Minimum and maximum nose cone diameters, maximum handle diameter, tail diameter, and grip to nose distance ranged from 1.57-3.33 mm (mean = 2.66 mm) and 6.20-12.70 mm (mean = 8.30 mm), 14.68-21.64 (mean = 17.10 mm), 4.01-8.32 mm (mean = 6.61 mm), and 14.05-22.97 mm (mean = 17.37 mm), respectively. Across the 20 MSFs, activation force, activation travel, and activation stiffness ranged from 2.02-4.66 N (mean = 2.91 N), 2.17-5.75 mm (mean = 3.85 mm), and 0.21-1.32 N/mm (mean = 0.66 N/mm), respectively.
Conlusions
The geometric dimensions and force required to activate MSF handles may affect the performance of these instruments. Significantly variability was observed in many of the measured characteristics. The Reflex handle (Alcon-Grieshaber) demonstrated relatively lower activation forces and higher activation stiffness in its 23-, 25-, and 27-gauge sizes in comparison to its counterparts. Additionally, its lightweight nature and sleek profile compared to other commercially-available forceps may offer benefits in terms of maneuverability, precision, and surgeon ergonomics. Further validation studies are needed.
Financial Disclosure
Alcon, Alimera Sciences, Allergan/AbbVie, Novartis, Regeneron, DORC, Genentech, REGENXBIO (consultant for all)
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