(a) Photo and graphic of the final intravitreal injection device. Design features include: 1) transparent body 2) stainless-steel-insert within needle guide with a large lead-in angle 3) vertical grips 4) smooth surface of the circular ring which is to be placed onto the eye 5) injection guide (b) Air bubble inside the injection guide (arrow) which was an artefact of the manufacturing process
Figure 1: Intravitreal injection device
Contrast-agent appears black (a) Illustration of the 5 compartments (red lines) used to score the location of contrast-agent-deposition (b) Contrast-agent in direct proximity and (c) not in direct proximity to the lens
Figure 2: Representative MR-Images of contrast-agent-deposition within the vitreous
Comparison of injections with the device used either with a 13-mm or a 19-mm-needle and freehand injection using a 13-mm-needle. A small score indicates contrast-agent-deposition in a desired central location. Injections which deposited the contrast-agent touching the lens are marked with "♦", injections which did not touch the lens are marked with "○"
Figure 3: MRI contrast-agent-deposition scores
The distance of injection site from retina/pars plana junction (0; marked with black horizontal line) in µm for the four different operators using device-guided and freehand injections. Injections through the pars plana are marked with (•), through the retina with (○) and through the ciliary body with (◊). The green horizontal line represents the mean width of the pars plana
Figure 4: Precision of needle-penetration-point following freehand and device-guided injection by experienced and novice operators
(a) Injection penetrating the retina and (b) Injection penetrating the pars plana. Turquoise lines and grey rectangles are the measurements taken with Hamamatsu’s NDP. View software. Arrowheads (►) mark the reference point retina/pars plana junction. Arrows () show the ciliary body/pars plana junction. N = needle penetration point; c = ciliary body; r = retina (*detached as artefact of fixation process); pp = pars plana
Figure 5: Representative histological images of the needle penetration point

Fixed injection angle


Fixed needle penetration point

3.2 mm posterior to limbus

Length of needle guide

7 mm

Fixed injection depth using 13-mm-needle

6 mm

Fixed injection depth using 19-mm-needle

12 mm

Needles which can be used

30G or insulin needle


Clear polycarbonate and metal inlet in needle guide


1.16 g


22 mm

Diameter of ring touching the eye

17.4 mm

Diameter of ring which is being held

15.7 mm


Ethylene oxide or autoclave

Table 1: Specifics of the novel intravitreal injection device