Abstract
Purpose :
Intravitreal injections (IVI) of different medications have associated risk of intraocular inflammation, and considered to be the main cause of intraocular septic and aseptic reaction. The mechanism of vitreous contamination remains unclear. We aimed to discover the cellular content in needle tip aspirates after standard IVI, and to compare it between different needle types.
Methods :
Thirty Wistar white outbred albino rats (age: 6 months, weight: ≈700 g) and human cadaver eye were used for IVI with hypodermic 27 gauge (G) and 30G needles, and spinal anesthesia Pencan 27G needles, with 10 injections pro one needle type. After transscleral penetration during IVI, an aspiration of vitreous was applied for quantitative morphological and cell cultivation analysis of needle tip aspirates, as well as cyto-histological analysis of aspirates and entry sites were performed. The results were analyzed using descriptive statistics, frequency tables, correlation matrices and t-test (p <0.05 considered statistically significant).
Results :
All aspirates showed a marked amount of cells presented with following morphological cell types: conjunctival, ciliary body non-pigmented epithelial, and sclerocyte-like cells and granular proteins (marker of cellular damage). Aspirates from 27G hypodermic needles (rat and cadaver eyes study) showed significantly higher amount of granulated proteins compared to 30G hypodermic and 27G Pencan needles (p<0.05). Study of entry sites of hypodermic needles showed marked trauma in all layers of the eye wall (rat and cadaver eyes study) associated with cellular destruction, compared to 27G Pencan needle, where partial reposition of sclerocytes after IVI was noticed. After 4 weeks of cultivation of aspirates in medium (cadaver eye study), adherent or gravitationally immobile proliferated conjunctival cells could be detected.
Conclusions :
Our results support the hypothesis that vitreous can be contaminated with cellular content cut by sharp inner edge of the tip of hypodermic needle which have been used routinely for IVI. Smaller gauge needle (30 G) causes less trauma leading to smaller amount of cells in the needle tip potentially injected into the eye. The alternative needle design and the possible consequences of cellular content being injected into the vitreous cavity need to be considered accordingly.
This is an abstract that was submitted for the 2017 ARVO Annual Meeting, held in Baltimore, MD, May 7-11, 2017.