: To assess the microvascular change of the optic nerve head and macula after acute rise of intraocular pressure (IOP) in normal and diabetic eyes.

In this prospective, interventional, comparative study, ten normal and sixteen diabetic eyes without diabetic retinopathy (NDR) or with mild non-proliferative diabetic retinopathy (NPDR) were enrolled. IOP rise induced by a suction vacuum attached to the sclera. IOP was measured and optical coherence tomography angiographic (OCTA) images were obtained from the optic disc and macula, before and after IOP rise. The repeatability of the device in the vessel density measurements was calculated by analyzing the two consecutive imaging-derived data of the subjects before the intervention.

The change in IOP after activation of the suction was significant in all three groups (all P < 0.05). There was no significant difference in the amount of IOP change between the three groups (all P > 0.05). The changes in the vessel density in the macular deep and superficial capillary plexus was statistically significant in whole image and parafoveal area in normal subjects (all P < 0.05). Also, the change in the vessel density was significant in the inside disc measurements in NPDR. Other microvascular changes were not statistically significant. All microvascular changes in all three groups were less than the measurement repeatability of the OCTA device.

Acute rise of IOP may induce different levels of microvascular changes in healthy and diabetic eyes. The results of this study may shed a light on the autoregulation mechanisms of the microvascular networks. Financial Disclosure: No