| Summary: | Lyubomyr M Lytvynchuk,1,2,* Goran Petrovski,3,* Adien Dam,4 Joep Hiemstra,4 Tobias Wimmer,1 Iryna Savytska,5 Susanne Binder,2,6 Knut Stieger1 1Department of Ophthalmology, Justus-Liebig-University Giessen, Eye Clinic, University Hospital Giessen and Marburg GmbH, Campus Giessen, Giessen, Germany; 2Karl Landsteiner Institute for Retinal Research and Imaging, Vienna, Austria; 3Center of Eye Research, Department of Ophthalmology, Oslo University Hospital and Institute of Clinical Medicine, University of Oslo, Oslo, Norway; 4Vitreq B.V., MG Vierpolders, the Netherlands; 5Department of Experimental Surgery, A.A.Shalimov National Institute of Surgery and Transplantology, National Academy of Medical Science of Ukraine, Kyiv, Ukraine; 6Department of Ophthalmology, Sigmund Freud University, Eye Center Donaustadt, Vienna, Austria*These authors contributed equally to this workCorrespondence: Lyubomyr M LytvynchukDepartment of Ophthalmology, Justus-Liebig-University Giessen, Eye Clinic, University Hospital Giessen and Marburg GmbH, Campus Giessen, Friedrichstrasse 18, Giessen, 35392, GermanyTel +49 64198543820Fax +49 64198543809Email Lyubomyr.Lytvynchuk@augen.med.uni-giessen.dePurpose: To study the efficacy of a novel needle for intravitreal injection (IVI) in comparison to the conventional needle under experimental conditions.Methods: The newly designed 30-gauge (G) needle (NDN) (EP 18158 542.3, patent pending) with occluded outer orifice and a side port for drug delivery was compared to the conventional standard hypodermic 30 G needle for IVI (SHN). An animal study to obtain needle tip aspirates was performed on 10 albino rat eyes. During IVIs, cellular content, which was cut by the needle tip, was aspirated. Cellular material was studied in regard to cell types and their quantity. The injection stream was studied using trypan blue dye in vitro and pig cadaver eyes. The penetration force was tested on polyurethane Testing Foil Strips PU 04 (Melab, Leonberg, Germany) by applying a velocity of 100 mm/min. The results were analyzed using descriptive statistics, correlation matrices and t-test methods with p< 0.05 as statistically significant.Results: Cytological analysis of the needle aspirates showed the presence of cellular content in each case. The amount of conjunctival, ciliary body epithelial cells and granulated basophilic protein sediments (sign of cellular damage) in the case of the NDN tips was significantly lower compared to the SHN. The average penetration force of the NDN was 0.791 N, and in the case of the SHN was 0.566 N. The injection stream study revealed a difference in the initial injection phase between the two needle types, although the diffuse filling of the vitreous area which surrounded the needle tip appeared to be similar.Discussion: The NDN demonstrated superior performance with regard to a significantly reduced number of cells being captured by the needle tip. Delivery of the injected fluid into the vitreous cavity was comparable. In order to investigate superior properties of the NDN needle design, further studies with improved prototypes would be necessary.Keywords: intravitreal injection, endophthalmitis, novel needle, needle tip, penetrating forces, injection stream
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