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V. S. De Stefano, J. J. K. Abechain, D. M. Verginassi, E. B. Rodrigues, E. H. Freymüller, M. Maia, A. S. Lima-Filho, F. Penha, E. Dib, M. E. Farah; Ultra-Structural Analysis of Needles for Intravitreal Injection. Invest. Ophthalmol. Vis. Sci. 2009;50(13):6068.
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© ARVO (1962-2015); The Authors (2016-present)
Intravitreal (IVT) injections are used for therapy of many retinal diseases and may cause side effects. The purpose of this study is to analyze the ultra-structure of various needles used for IVT.
Twelve needles of 5 different brands were assessed: BD® (BD, Franklin Lakes, NJ, USA), Terumo® (Terumo Inc., Tokyo, Japan), KDL® (KDL, Pacoima, CA, USA), Unijet® (Plascalp, Brazil), Nipro® (Nipro Inc., Osaka, Japan) ranging from 26 to 31 gauge and 8, 12.7 and 13mm. Five different angled photographs were taken using scanning electronic microscopy (SEM) (Jeol® JSM 3500, Tokyo, Japan): internal surface (IS), whole bevel vision (WBV), bevel apex (BA), bevel basis (BB) and hub segment (HS). The analysis was done looking for: A. form of irregularities on surface; B. number of irregularities on surface; C. sharpness of tip; D. number of edges at bevel; E. debris of lubrication process.
IS analysis showed many forms of irregularities in all needles assessed. WBV photos revealed that BD needles have three different edges on their bevels; other brands showed only two. The bevel was straighter in BD when compared to Terumo needles. In this regard, Nipro was similar to BD. BA pictures illustrated that BD needles became sharper as gauge increased. Terumo had the roundest tips, while KDL, the sharpest. The surface of the bevel, analyzed through BA and BB images, showed wrinkled patterns for Terumo needles. BD presented many kinds of irregularities; except for the 31G needle, which was more regular. KDL and Unijet were also irregular, the latter and Nipro showing longitudinal striate accidents. HS photos showed that Nipro had the flattest surface, whilst BD presented many irregularities deposit-like close to its proximal opening. Examples of some photos are displayed on the image below.
Ultra-structure of needles used for IVT varies from one brand to another. The surface of the needles shows irregularities and debris, which may interfere with the maneuver of scleral entry, the incidence of post-operative inflammatory reactions and injection outcomes.
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