Experimental assessment of the performance of vitreous cutters with fluids with different rheological properties.

PURPOSE: To assess the influence of rheological properties of an artificial vitreous (AV) on the performance of double-blade (DB) and single-blade (SB) guillotine vitreous cutters, with 23-, 25-, and 27-gauge (G) probes. METHODS: We evaluate the aspiration flow rate, using an optical method, based on image processing. Experiments are conducted using ten viscoelastic vitreous phantoms, with different properties that are measured with rheological tests. RESULTS: Aspiration rate strongly varies with fluid properties. Regardless of cutter geometry and operational conditions, the flow rate significantly decreases as vitreous viscosity and elasticity increase. CONCLUSIONS: All tested vitreous probes are very sensitive to changes in fluid rheology. SB cutters produce smaller flow rates compared with DB ones of the same caliber; however, they are less sensitive to fluid properties at low aspiration pressures. The use of vitreous substitutes for test performance guarantees comparability between flow rate results achieved with different vitrectomy systems operating in different media. This outcome is further confirmed by the low values of estimated flow rate relative errors.

Fluid Dynamic Assessment of Hypersonic and Guillotine Vitrectomy Probes in Viscoelastic Vitreous Substitutes.

Purpose: To assess the fluidics of 23-gauge (G) large-port (L) and tear drop-port (TD) hypersonic vitrectomy probes (HVPs) compared with guillotine vitrectomy probes (GVPs) of various calibers (23G, 25G, and 27G) and geometries (single and double blades). Also, to identify the working parameters that provide the best balance between acceleration and flow rate, and, for HVPs, to measure temperature variations in the fluid. Methods: We used particle image velocimetry to measure flow fields in balanced salt solution and viscoelastic artificial vitreous. We analyzed acceleration, kinetic energy, and volumetric flux. The parameters considered were vacuum pressure, ultrasound stroke, and cut rate. Temperature measurements were taken using an infrared thermal camera. Results: The flow rate was significantly higher for HVPs than GVPs. With both probes, flow rate and acceleration increased with vacuum pressure. Flow rate depended weakly on the ultrasound stroke or cut rate. In HVPs, the acceleration peaked at a stroke of 30 µm, whereas in GVPs it peaked at a cutting rate of 4000 to 5000 cuts per minute (cpm). The HPV/TD combination generated higher flow rates and lower accelerations than did HPV/L. The increase in temperature was small. Conclusions: Under the present experimental setup and medium, HVPs offered better fluidics compared with GVPs in terms of flow and acceleration; however, the flow structure for HVPs is more complicated and unsteady. The HPV/TD combination produced larger flows than did the HPV/L combination and slightly smaller accelerations. HPVs generated a small temperature increase. Translational Relevance: In the tested artificial vitreous, HVPs were found to be more efficient in terms of generating lower acceleration for a given flow rate. The slight increase in temperature observed with HVPs is unlikely to be clinically significant.

Curcumin-Based Treatment for Macular Edema from Uncommon Etiologies: Efficacy and Safety Assessment.

The aim of this study was to investigate the efficacy and safety of curcumin formulation with a polyvinylpyrrolidone-hydrophilic carrier (CHC*; Diabec®-AlfaIntes, Italy) for the treatment of macular edema (ME) from uncommon etiologies. We conducted retrospective interventional case series, reviewing the medical records of patients referred to the Eye Center, Humanitas Hospital, Bergamo due to persistent ME related to uncommon causes and treated by oral administration of CHC. The main outcomes assessed were best-corrected visual acuity (BCVA), central macular thickness (CMT), and the presence of intraretinal and/or subretinal fluid (SRF). Only patients with a minimum follow-up (f/u) of 6 months were included. The occurrence of any adverse effect was registered. Thirty-one eyes of 30 patients were included, with a mean f/u of 8.32 ± 1.77 months. Of them, 9 patients (10 eyes) were affected by postoperative ME and 21 by chronic central serous chorioretinopathy. Median BCVA significantly improved after treatment, changing from 0.3 [0.16-0.5] to 0.1 [0-0.3] logarithm of the minimum angle of resolution (P < .001). Also CMT was significantly improved, as it decreased from 400 [364-438] µm before treatment to 280 [242-307] µm at the last f/u visit (P < .001). The complete absorption of intraretinal/SRF was detected in 23 of 31 eyes (74%) at the final f/u. No adverse effects were registered. In conclusion, treatment with CHC was effective and safe for eyes affected by ME of various uncommon etiologies, resulting in significant improvement of both functional and anatomical outcomes, with the complete resolution of the edema in the majority of cases (74%).