The study of needle tip aspirates and entry sites after intravitreal injections with different needle types
Abstract
Purpose
To compare the entry site and study the cellular content of different needle tip aspirates after transscleral intravitreal injection (IVI) on rat eyes.
Methods
The intravitreal injections (IVI) were performed on 20 white outbred rat eyes (10 IVI with 30-gauge subcutaneous needles (SCN), 10 with 27-gauge Pencan needle (PCN) (B. Braun)). The 1.0 cc syringes were preloaded with 0.02 cc of balanced salt solution (BSS) and connected to the needles. The penetration was performed 1 mm posterior to the limbus, followed by aspiration of 0.01 cc vitreous body. Aspirated material was evacuated onto glass slides and stained by Azure-2-Eosin. Enucleation and histological analysis of the IVI entry site was performed at magnification 100 and 400 times.
Results
Cellular content of the aspirated material was revealed in all cases. The aspirated cells represented conjunctival epithelial-, ciliary body non-pigmented epithelial-, sclerocyte-like cells and vitreous crystallised specimens. The amount of conjunctival epithelial cells prevailed in 27-gauge PCN IVI cases. The stained granular proteins were less significant in the case of 27-gauge PCN tips. The entry sites after 30-gauge SCN injection showed concrete cut of all tissues, while partial reassembling of the sclerocyte bindings was seen after 27-gauge PCN injections.
Conclusions
The use of 30-gauge SCN and 27-gauge PCN needles for transscleral IVI has resulted in trauma of all layers of the rats’ eye wall. Histological analysis of the needle tip aspirates showed less tissue damage by 27-gauge PCN; moreover, the SCN tips created complete cuts due to their sharp edges, in contrast to the PCN tips.
