**Purpose**:
Manufacturers of surgical instrumentation have increasingly sought to decrease the size of ophthalmic surgical instruments. We have used finite element modeling to model the stress and strain present in a fragmatome as a function of driving frequency and fragmatome dimensions.

**Methods**:
Finite element calculations using the COMSOL Multiphysics system v3.5 were used to elucidate the influence of wall thickness, length, and excitation frequency on a titanium fragmatome tube with outer diameters of 20, 23, 25, and 27 gauge.

**Results**:
By coupling structural mechanics, fluid mechanics, and acoustical physics, we were able to determine the eigenfrequencies (resonant frequencies) as well as parameters in which the von Mises stress in a fragmatome tube exceeds the yield strength, leading to destruction of the instrument.

**Conclusion**:
Solid fragmatomes have far fewer possible failure modes than fragmatomes with a standard wall thickness. Eigenfrequency analysis and finite element calculations can be critical in predicting potentially catastrophic designs in modern surgical instruments.

**Translational Relevance**:
Instruments developed for microsurgical applications cannot always simply be scaled down versions of conventional instruments. Such an approach can lead to potentially dangerous intraoperative failures, such as a fragmatome shattering inside the eye. Modern engineering techniques are increasingly necessary to investigate potential instrument failure mechanisms and to optimize device performance in a design in silico before in vivo testing.

^{1–3}decreased rates of infection,

^{4–9}better healing at the site of incision,

^{9}and faster recovery

^{1,5}in various surgical settings. Thus, the design, safety, and efficacy of smaller-diameter, modern surgical instruments are of growing interest.

^{5}absence of sclerotomy sutures, which may then lead to reduced suture-induced astigmatism

^{10}inflammation and pain postoperatively,

^{11–13}as well as reduced intraocular inflammation.

^{14}A retrospective study comparing the use of a 23-gauge fragmatome with and without a 20-gauge trocar reported that the tip of the fragmatome fractured and had to be surgically retrieved.

^{15}This incident highlights a possible safety concern with smaller gauge instrumentation and, in particular, a smaller gauge fragmatome. We used finite element modeling to study the von Mises stress and strain present in a fragmatome as a function of frequency and fragmatome dimensions to predict potentially catastrophic designs. Finite element analysis is a computational tool that can be used for calculating forces, deformations, stresses, and strains at any point in a structure, such as a fragmatome.

^{16}the fragmatome can break apart. The finite element calculations allowed for visualization of the von Mises stress and volumetric strain (change in volume/volume) of the fragmatome. The fragmatomes simulated were made of titanium.

*R*

^{2}of 0.9996 (Fig. 1, Table 1) for all gauges. The exponential one phase decay fit for 20-, 23-, 25-, 27-gauge curves are statistically not different from each to other (Table 1). Likewise for a solid fragmatome, the relationship between eigenfrequency and tube length for 20-, 23-, 25-, and 27-gauge fragmatomes also can be fit with an exponential one phase decay function all with an

*R*

^{2}greater or equal to 0.999 (Table 2) and the exponential one phase decay fit for 20-, 23-, 25-, and 27-gauge are statistically not different from each other (Table 2). Comparing the decay constant

*K*of an exponential one-phase decay fit of the solid fragmatomes to that of the hollow standard wall thickness fragmatomes, the decay constants are statistically not different between a solid and a hollow fragmatome for all gauges (Tables 1, 2). Based on analysis of variance (ANOVA) of the undamped eigenfrequencies at various fragmatome lengths, we did not find a statistically significant interaction between the groups analyzed, including different gauges, wall thicknesses, or the interaction between gauge and wall thickness (Table 3).

^{17}) or breakage during use (sudden failure

^{17}).

^{15}reported a case of a 23-gauge fragmatome fracturing at the distal shaft near the tip during the surgery; as can be seen in the photo of the broken fragmatome in that study, the length of fragmatome was approximately 30 mm (Fig. 4E.2).

^{15}This catastrophic event provides supports for the validity of our finite element calculations.

^{15}As the trend toward miniaturization of surgical instrumentation proceeds, such modern engineering analysis will become increasingly crucial. In addition, such techniques may allow optimization of a device under design.

**W.J. Foster**, Small diameter fragmatome for minimally traumatic retained lens fragments removal, United States Patent 9050171 (P);

**J.J. Wang**, None

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