Abstract
Purpose:
To evaluate the short term change in intraocular pressure (IOP) as a result of injecting up to 500 µL of ink into the suprachoroidal space(SCS) and the vitreous in ex-vivo porcine eyes.
Methods:
Sixty enucleated porcine eyes were fitted through the optic nerve with a 21 gauge needle attached via catheter to a deionized water intravenous (IV) drip. The IV was suspended to a height that would allow the eye to equilibrate to an IOP of 15 mmHg to mimic average in vivo conditions. Suprachoroidal space injections were performed in 45 of the eyes using an 800 ± 25 μm 33 gauge microneedle. Intravitreal (IVT) injections were performed in 15 of the eyes using a 13 mm 33 gauge needle. Volumes of 100, 200, 300, 400, and 500 μL were injected for both types of injections. A 1:3 dilution of acrylic ink (Speedball Art Products, Statesville, NC) in balanced salt solution was injected in all cases. Intraocular pressure measurements were taken before and after injection (1 min post-injection) using a Medtronic Tono-Pen ® XL.
Results:
SCS injections caused a mean increase in IOP of 13.8 ± 3.3, 33.3 ± 2.8, 43.3 ± 3.2, 58.8 ± 4.2, 70.9 ± 3.7 mmHg for injection volumes of 100, 200, 300, 400, and 500 μL, respectively. IVT injections caused a mean increase in IOP of 14.3 ± 2.3, 32.7 ± 2.5, 44.3 ± 5.0, 62.7 ± 2.5, 74.0 ± 1.0 mmHg for injection volumes of 100, 200, 300, 400, and 500 μL, respectively. IOP increased linearly as injection volume increased for both injection types. At a specified injection volume, there was no statistically significant difference between IOP increases observed following SCS injections and IVT injections (P ≥ 0.17). Eyes which received SCS injections of 400 and 500 μL were dissected following their final IOP measurement to ensure that no damage was done to the retina and the ink remained within the suprachoroidal space. No ink was found in the vitreous, and no observable damage was done to the retina.
Conclusions:
There is no statistically significant difference between the initial IOP increase following SCS and IVT injections.
Keywords: 561 injection •
568 intraocular pressure