Optical Coherence Tomography of Peripapillary Vessels in Giant Cell Arteritis and Ischaemic Ocular Disease.

With normal retinal blood flow, cross-sectional optical coherence tomography (OCT) of retinal vessels shows a structured intravascular reflectivity profile, resembling a 'figure-of-8'. Altered profiles have been reported in vascular occlusive and haematological diseases. Giant cell arteritis (GCA) can cause visual loss, usually due to anterior ischaemic optic neuropathy (AION) or retinal artery occlusion. Our aim was to extend the assessment of OCT vascular profiles to patients with suspected GCA and to determine if any abnormalities were related to GCA per se or to ischaemic ocular conditions. This nested retrospective study included 61 eyes of 31 patients (13 with GCA). Six eyes had arteritic and seven eyes non-arteritic AION, three eyes had non-arteritic retinal artery occlusion, 11 eyes had other ocular conditions and 34 were unaffected control eyes. For each eye the appearance of structured intravascular profiles on peripapillary OCT was graded as present, partial, absent or uncertain. Non-presence of structured intravascular profiles was more frequent in AION and retinal artery occlusion than in other ocular conditions or unaffected eyes (Fisher's test, p = .0047). Based on follow-up of 25 eyes, reflectivity profiles normalised in three out of four eyes after 85 (35-245) days. Vessel profiles were not associated with GCA (p = .32) and were similar in arteritic and non-arteritic AION (p = .66). In conclusion, absence of structured intravascular reflectivity profiles may be a marker of acute ischaemia in the anterior optic nerve or inner retina. However, it did not seem specific for GCA. The prognostic value warrants further studies.

Spectral-domain optical coherence tomography of retinal vessels in Waldenström's macroglobulinemia.

PURPOSE: To image retinal blood vessels in patients with Waldenström's macroglobulinemia using optical coherence tomography (OCT). METHODS: Retrospective case series examining fundus photographs and OCT scans of 16 eyes in eight patients with Waldenström's macroglobulinemia. Analyses included intravascular OCT reflectivity profiles and vessel diameters, and their relation to total immunoglobulin M (IgM) levels. RESULTS: In six out of eight patients, cross-sectional OCT scans of larger retinal vessels (diameter > 100 µm) showed normal intravascular reflectivity and retrovascular shadowing. In two patients with the highest total IgM > 60 g/l, altered intravascular reflectivity, distinct anterior and posterior vessel wall reflexes, and retrovascular hyposhadowing were seen. Normalization of the OCT reflectivity in these patients occurred after reduction of total IgM to < 17 g/l and was accompanied by decreasing venous tortuosity and disappearance of retinal haemorrhages and cotton wool spots. CONCLUSION: This study found that Waldenström's macroglobulinemia and total IgM > 60 g/l were associated with abnormal intravascular reflectivity and retrovascular shadowing on OCT. Awareness of these signs of hyperviscosity could potentially enable earlier detection of critical conditions in patients with Waldenström's macroglobulinemia and improve the assessment of severity and treatment effect.

RELATION BETWEEN FLUORESCEIN ANGIOGRAPHIC AND SPECTRAL-DOMAIN OPTICAL COHERENCE TOMOGRAPHY FINDINGS OF BLOOD FLOW TURBULENCE AT ARTERIOVENOUS CROSSINGS IN THE RETINA.

PURPOSE: To examine retinal blood flow at arteriovenous crossings using spectral-domain optical coherence tomography (SD-OCT). METHODS: Retrospective observational case series of 11 arteriovenous crossings in 10 eyes examined by SD-OCT and fluorescein angiography on suspicion of manifest or imminent branch retinal vein occlusion. RESULTS: Fluorescein angiographic evidence of turbulence was seen at 5 of 11 arteriovenous crossings, whereas laminar angiographic flow was intact at the crossing and downstream thereof at the remaining 6 crossings. On SD-OCT, chaotic reflectivity patterns were seen at the point of crossing and downstream thereof in all 5 cases with angiographic turbulence, whereas an intravascular trilayer SD-OCT pattern consistent with laminar flow was seen throughout the examined course of the vein in the eyes with laminar angiographic flow. CONCLUSION: We examined retinal blood flow at and near arteriovenous crossings and found that SD-OCT may rival fluorescein angiography in the ability to demonstrate turbulent venous blood flow.

Non-invasive imaging of retinal blood flow in myeloproliferative neoplasms.

PURPOSE: To study the circulation in the retinal vessels in patients with blood dyscrasia due to myeloproliferative neoplasms using non-invasive retinal imaging. METHODS: Prospective consecutive case series of seven treatment-naïve patients with chronic myeloid leukaemia (n = 2), polycythemia vera (n = 4), essential thrombocytosis (n = 1) examined before and after cytoreductive treatment. We investigated retinal circulation with motion-contrast imaging, retinal oximetry and spectral-domain optical coherence tomography. RESULTS: Retinal venous blood velocity increased by 8.14% (CI95 3.67% to 12.6%, p = 0.004) and retinal arterial oxygen saturation increased by 7.23% (CI95 2.9% to 11.6%, p = 0.010) at follow-up (mean 12 weeks, range 5-14 weeks) where complete haematological remission had been achieved by cytoreductive treatment. Abnormal optical coherence tomography reflectivity patterns were present at baseline in patients with chronic myeloid leukaemia and were replaced by normal patterns at follow-up. Retinopathy, in the form of cotton-wool spots and retinal haemorrhages, was found at presentation in the two patients with chronic myeloid leukaemia and in one patient with polycythemia vera. The retinopathy had resolved at follow-up in all patients. CONCLUSION: With non-invasive retinal imaging, we were able to demonstrate increased retinal venous blood velocity, increased retinal arterial blood oxygenation and normalization of intravascular reflectivity patterns after successful treatment of myeloproliferative neoplasms. Larger prospective studies are needed to assess the prognostic value of these non-invasive imaging methods in predicting circulatory complications in myeloproliferative neoplasms.

Flow patterns on spectral-domain optical coherence tomography reveal flow directions at retinal vessel bifurcations.

PURPOSE:   To study intravascular characteristics of flowing blood in retinal vessels using spectral-domain optical coherence tomography (SD-OCT). METHODS:   Examination of selected arterial bifurcations and venous sites of confluence in 25 healthy 11-year-old children recruited as an ad hoc subsample from the population-based, observational Copenhagen Child Cohort 2000 study. RESULTS:   The blood stream in retinal arteries maintains a figure-of-8 SD-OCT profile consistent with a laminar flow in concentric sheets and a parabolic velocity distribution up to the point of divergence at arterial bifurcations. In contrast, the blood stream at the site of confluence of two retinal veins remains divided into two parallel sets of sheets with separate velocity distribution for a downstream distance of at least four trunk vessel diameters. Consequently, retinal trunk vessels near bifurcations/confluences have distinctly different internal SD-OCT profiles, a figure-of-8 pattern in arteries and a figure figure-of-88 in veins that can be used to distinguish between the two vessel types. CONCLUSION:   This study verified the hypothesis that directions of blood flow at dichotomous vascular branchings can be determined using SD-OCT. This feature may assist the identification of flow reversal near sites of vascular occlusion, the analysis of blood flow near vascular malformations and the segmentation of retinal SD-OCT images.

Retinal and choroidal intravascular spectral-domain optical coherence tomography.

PURPOSE: To examine retinal and choroidal blood vessels using spectral-domain optical coherence tomography (SD-OCT). METHODS: Retrospective case series. RESULTS: Scans through retinal blood vessels in healthy subjects demonstrated vessel wall reflexes and a tri-layer profile of the blood column on longitudinal scans and a figure-of-eight configuration on cross-sectional scans. Intravascular reflectivity decreased with increasingly oblique angles of observation and was absent when blood flow was parallel to the line of sight. The high blood flow in the choroidal vessels in healthy subjects and the low flow in the retinal vessels in patients with ocular ischaemic syndrome and central retinal artery occlusion were both associated with lower reflectivity of the blood and an unstructured intravascular SD-OCT profile. DISCUSSION: This qualitative in vivo study found a characteristically structured SD-OCT profile of the blood column in retinal vessels with normal blood flow. Both structure and total reflectivity faded when blood flow was lower or higher than normal or at oblique angles to the line of sight. In conclusion, SD-OCT scans of the vessels in the posterior pole of the eye may assist the clinical assessment of gross abnormalities of ocular blood flow, e.g. in carotid artery stenosis.