First Author: C.H.Meyer SWITZERLAND
Co Author(s): Z. Liu C.K. . Brinkmann E.B. Rodrigues T. Bertelmann 0 0 0 0 0 0 0 0 0
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To investigate the geometry, penetration force and cutting profile of the novel and old needle of the drug delivery system (DDS) for Ozurdex injections in a standardized laboratory setting.
Department of Ophthalmology, Pallas Clinic Aarau
The normative geometrical data of the DDS-needle were systematically analyzed according to nomenclature DIN 13097 (ISO 7864) and ISO 9626. Force to penetrate a standardized 0.4 mm thick polyurethane foil was measured by a Penetrometer, when the needle was piercing, cutting and sliding through the foil and plotted as a load-displacement diagram. Magnified images of the consecutive cut were taken after the entire penetration through the foil.
The mean point length was equal to 3.34 mm (3.28 – 3.36) for the old DDS-needle vs. 3.33 mm (3.30 – 3.36) for the new DDS-needle. The secondary bevel length was 1.64 mm (1.42 – 1.73) for the new and 1.66 mm (1.62 – 1.69) for the old needle. The primary angle was 9.2° (9.0° – 9.5°) for the old and 8.9° (8.5° – 9.0°) for the new needle respectively. The secondary bevel angle was 117.2° (116° – 118°) for the old and 111.4° (116° – 118°) for the new needle. The mean penetration force of the old DDS-needles was significant higher at all phases of the penetration experiment: The mean piercing force was 0.7 Newton (N) with the old and 0.47 N with the new DDS- needle. The mean cutting force was remarkable higher with 1.1 N for the old DDS–needle vs. 0.78 N for the new DDS-needle. The dilatation phase was statistical not significant between 0.94 N and 0.99 N in both DDS-needles.
A comparison of the old and new DDS-needle demonstrated a reduced penetration force with the modified new DDS-needle, which may help to achieve a smooth penetration through the human sclera.