Differential reperfusion patterns in retinal vascular plexuses following increase in intraocular pressure an OCT angiography study

Abstract

To describe patterns of reperfusion in the superficial vascular plexus (SVP), deep capillary plexus (DCP) and choriocapillaris (CC) as detected on optical coherence tomography (OCTA) in cynomogulus macaque monkey model following increase in intraocular pressure by an intravitreal injection. Animal imaging study. Two cynomogulus macaque monkeys. A 100 µL intravitreal injection (IVI) of saline was given in one eye of each monkey. Serial OCTA using a Zeiss Plex Elite 9000 was used to evaluate reperfusion patterns within the SCP, DCP, and CC. OCTA evidence of perfusion. Pulsation of the central retinal artery was detected after the intraocular pressure was elevated to 98 and ≥ 99 mmHg from IVI. Episodic flow within the SVP arterioles and venules and poor visualization of flow in capillaries was noted during the initial phase of elevated pressure. As the pressure declined, the flow signal within the DCP appeared initially as dots, which progressed laterally to loops which form capillary vortex configuration. Recovery of flow within the SVP and CC appeared sooner than in the DCP. At 40 min after the injection, well after the intraocular pressure normalized, the retinal and choriocapillaris vascular perfusion showed focal defects in every layer. Compared with pre-injection images, vessel density in the DCP was 68.8% and 78.6% of baseline in monkey 1 and monkey 2, respectively. In contrast vessel density in the SVP recovered to 84.2% and 88.9% of baseline. Increases in intraocular pressure from IVI have the potential to affect every layer of blood flow in the fundus. After nominal return of intraocular pressure, focal defects in flow persisted, which may result in longer term damage to the retina.

Bilateral anterior ischemic optic neuropathy and choroidal ischemia in a patient with COVID‐19 infection

“… 8 Another study assessing the perfusion patterns of superficial and deep capillary plexus (SCP, DCP) and choriocapillaris (CC) following intravitreal injection of Bevacizumab found that DCP is affected the most, followed by CC and SCP. 9 In our patient, we observed about 20 mm Hg rise in IOP, but despite severe choroidal ischemia in ICG, FA which shows retinal vasculature was not significantly affected. Moreover, EDI‐OCT showed reduced choroidal thickness in patients with choroidal ischemia caused by elevated IOP in the acute phase, 10 while in the present case, the choroidal thickness has been increased.…”

“…In a study of patients with narrow anterior chambers, it was found that choroidal capillary blood flow decreased significantly when IOP elevated greater than 10 mm Hg, and retinal vessel density decreased significantly when IOP increased more than 20 mm Hg 8 . Another study assessing the perfusion patterns of superficial and deep capillary plexus (SCP, DCP) and choriocapillaris (CC) following intravitreal injection of Bevacizumab found that DCP is affected the most, followed by CC and SCP 9 . In our patient, we observed about 20 mm Hg rise in IOP, but despite severe choroidal ischemia in ICG, FA which shows retinal vasculature was not significantly affected.…”

Acute and Subacute Intraocular Pressure and Macular Microvascular Structure changes after Intravitreal Ranibizumab Injection in Eyes with Branch Retinal Vein Occlusion

“…Some authors have shown that IOP spikes and changes in OCTA parameters can be observed post-IV, however, the results are still controversial. [14][15][16] In this study, we analyzed the acute and subacute alterations in IOP and macular microvascular changes in OCTA parameters in patients with BRVO post-IVI.…”

“…Whether the acute and subacute post-IVI IOP changes are associated with macular microvascular structure changes is still controversial. [14][15][16] In this study, we aimed to quantitatively investigate the acute and subacute changes in the IOP and macular microvascular structure in a cohort of patients undergoing intravitreal ranibizumab injection for ME following BRVO, to better understand retinal perfusion changes associated with IVI and also the correlation with the post-IVI IOP changes.…”

Differences in Vascular Density between Detached and Nondetached Areas in Eyes with Rhegmatogenous Retinal Detachment

“…The VD of the DCP and CCP was measured in a 0.45 × 0.45 mm area centered at 1.2 mm from the fovea in a contralateral position to the fovea in the detached area and nondetached area ( Figure 1 ). OCTA images of the DCP and CCP were binarized by the Otsu method [ 21 ]. The VD was calculated as the ratio of the area occupied by vessels divided by the total area of the binarized image.…”