Table 2 Studies of retinal and cerebral blood flow changes in sepsis, other haemodynamic disturbances, and other inflammatory disorders
From: Retinal blood flow in critical illness and systemic disease: a review
Sepsis studies | Species | Imaging modality | Pathology | Metrics measured | Findings |
|---|---|---|---|---|---|
Taccone et al. [10] | Animal (ovine) | SDF videomicroscopy of the cerebral cortex—Microscan; MicroVision Medical | Septic model | Total perfused vessel density Functional capillary density Small perfused vessels Perfused capillaries | Septic animals showed progressive reduction in all metrics compared to control group, suggesting cerebral microcirculatory impairment |
Crippa et al. [12] | Human | Transcranial Doppler of the middle cerebral artery—Compumedics DWL, Dresden, Germany | SABD | Cerebral autoregulation by blood flow velocity and mean flow index | Cerebral autoregulation impaired, cerebral blood flow increased and SABD in at least 50% of septic patients No difference in mean flow index between survivors and non-survivors |
Simkiene et al. [34] | Human | Portable IDF of conjunctival microcirculation—Cytocam®, Braedius Medical, Huizen, The Netherlands Fundus imaging—Optomed Aurora (Optomed Oy, Oulu, Finland) | Sepsis or septic shock | MFI TVD PVD Retinal arteriolar and venular calibre | Lower MFI, TVD and PVD in all septic patients than healthy controls Lower MFI in non-survivors than survivors TVD and PVD and arteriolar calibre associated |
De Backer and Creteur [107] | Human | OPS imaging of sublingual mucosa—Cytoscan ARII; Cytometrics | Sepsis, pre-cardiac surgery patients, ICU controls | Vascular density | Septic patients had decreased vascular density compared with all other groups |
Kanoore Edul et al. [108] | Human | SDF microscopy imaging of sublingual mucosa—Microscan; MicroVision Medical | Septic shock | MFI Perfused capillary density | Hypoperfusion and microcirculatory abnormalities in septic patients compared with healthy controls, which were more severe in non-survivors |
Hessler et al. [112] | Ovine | Portable IDF of sublingual and conjunctival microcirculation—Cytocam®, Braedius Medical, Huizen, The Netherlands | Sepsis and haemorrhagic shock | MFI TVD PVD PPV | Lower PVD, PPV and MFI in haemorrhagic and septic shock in mouth and conjunctiva than control group No change in TVD |
Pranskunas et al. [113] | Pig | SDF videomicroscopy of sublingual, conjunctival, jejunal and rectal microcirculation—Microscan; Microvision Medical, Amsterdam, The Netherlands | Sepsis | MFI PPV PVD TVD | Lower MFI and PPV observed in all locations in the sepsis group than control group, with the lowest MFI in sublingual region No change in TVD Sublingual associates with conjunctival MFI |
Taccone et al. [55] | Animal (ovine) | SDF videomicroscopy of cerebral cortex—MicroScan (MicroVisionMedical, Amsterdam, The Netherlands) | Sepsis | Mean flow index Proportion of small perfused vessels Functional capillary density Lactate/pyruvate ratio (tissue hypoxia) | Cerebral functional capillary density and proportion of small perfused vessels decreased significantly from baseline to shock onset, compared with control group Brain oxygen levels reduced while lactate/pyruvate ratio increased in septic animals Suggests impaired cerebral microcirculation in septic animals |
Alnawaiseh et al. [123] | Animal (ovine) | OCTA—RTVue XR Avanti with Angiovue, Optovue Inc | Haemorrhagic shock | Flow density | Reduced flow density of the superficial retina after shock induction, which recovered after resuscitation |
Park [124] | Animal (rat) | OCTA (manufacturer not specified) | Haemorrhagic shock and sepsis | BFI against MAP and lactate | As MAP decreased in the haemorrhagic shock model, BFI of the choroid but not retinal artery decreased and was associated with increased lactate concentration in sepsis |
Erikson et al. [125] | Human | FFA—HRA 2–00153; Heidelberg Engineering, Heidelberg | Sepsis | RAFT Inflammatory markers | Retinal abnormalities observed in half of the patients with sepsis, being more common in those showing PRAFT Patients with PRAFT had lower levels of CRP and IL-6 compared with patients who had SRAFT, suggesting impaired inflammatory response |
Simkiene et al. [126] | Human | Fundus imaging—Optomed Aurora (Optomed Oy, Finland) | Sepsis | Retinal arteriolar and venular calibre Retinal vascular length density | Retinal arteriolar calibre higher in septic than healthy control patients, but venular calibre did not differ Septic patients had lower retinal vascular length density |
Other haemodynamic disturbances studies | Species | Imaging modality | Pathology | Metrics measured | Findings |
|---|---|---|---|---|---|
Chua et al. [15] | Human | OCTA—AngioVue; Optovue, Inc | Systemic hypertension | Retinal vessel density | Vessel density was reduced in patients with poorly controlled blood pressure compared with those with well controlled blood pressure |
Terheyden [114] | Human | OCTA—PLEX Elite 9000, Carl Zeiss Meditec Inc | Systemic hypertensive crisis | Retinal vessel density Skeletal density Vessel density index | Reduced skeletal density in the S-RL and D-RL and reduced vessel density in the D-RL in hypertensive patients compared with healthy controls |
Alnawaiseh [115] | Human | OCTA—RTVue XR Avanti with AngioVue, Optovue, Inc | AF | FAZ area Flow density | No difference found in FAZ area between groups Flow density in the superficial retina and ONH were lower in the AF group |
Arnould and Guenancia [116] | Human/ | OCTA—Cirrus HD-OCT, model 5000, Carl Zeiss Meditec | ACS | Retinal vascular density of SCP | Vascular density of SCP negatively associated with cardiovascular risk factors and left ventricular ejection fraction at admission |
Wang et al. [117] | Human | OCTA—AngioVue, Optovue, Inc | Coronary heart disease | Retinal vessel density Flow area | Some early stage coronary heart disease patients showed reduced vessel density, and reduced choroidal vessel density and blood flow |
Lin [120] | Human | OCTA (manufacturer not specified) | High-risk pregnancies | Retinal vessel perfusion density/vessel length density of SVP, ICP and DCP | Reduced SVP perfusion density and vessel length density in high-risk pregnancy individuals compared with low-risk pregnancy individuals |
Other inflammatory disorders studies | Species | Imaging modality | Pathology | Metrics measured | Findings |
|---|---|---|---|---|---|
Kılınç Hekimsoy et al. [118] | Human | OCTA—XR Avanti AngioVue | Systemic sclerosis | FAZ area and perimeter Vessel density | Patients with systemic sclerosis showed significantly decreased vessel density compared with controls, but there was no difference in FAZ area or perimeter |
Nakayama [16] | Human | OCT/OCTA—Topcon Triton, Topcon | IBD | FAZ area | Patients with active disease showed decreased FAZ area compared with patients in remission |