Superficial Capillaries Research Articles

Effects of repeated low-level red-light therapy on macular retinal thickness and microvascular system in children with myopia

ObjectiveThe objective of the study was to use optical coherence tomography angiography (OCTA) to analyze the effects of repeated low-level red-light (LLLT) therapy on macular retinal thickness and the microvascular system in children with myopia to evaluate the safety of this therapy. MethodsThis prospective study included 40 school-age children with myopia (80 eyes), aged 7–14 years, who received therapy using a LLLT instrument. At baseline and therapy for 1 month, 3 months, 6 months, all children underwent comprehensive ophthalmological examinations, including slit-lamp examination, uncorrected visual acuity, best-corrected visual acuity, spherical equivalent degree, axial length, and OCTA. The vessel densities of the superficial retinal capillary plexus, macular inner retinal thickness, and full-layer retinal thickness were measured. ResultsThe macular inner retinal thickness increased at 1 month and remained unchanged thereafter, It differed significantly in nine areas at 1, 3, and 6 months compared to the thicknesses before therapy (P < 0.05); however, we observed no significant differences between the different time points (P > 0.05). The macular full-layer retinal thickness increased at 1 month and remained unchanged thereafter; the changes showed significant differences at 1 month and 3 months compared to before therapy, for the inner nasal region (P < 0.05). The other eight areas showed significant differences at 1, 3, and 6 months compared with before therapy (P < 0.05); however, no significant difference was observed between the different time points after therapy (P > 0.05). The vessel density of the superficial retinal capillary plexus did not differ significantly among the four groups (P > 0.05). ConclusionsLLLT therapy was safe. The school-aged children exhibited macular thickening after LLLT therapy, which had no significant effect on macular microcirculation.

Quantitative Analysis of Retinal Perfusion in Patients with Frontotemporal Dementia Using Optical Coherence Tomography Angiography.

Optical coherence tomography angiography (OCT-A) provides detailed visualization of the perfusion of the vascular network of the eye. While in other forms of dementia, such as Alzheimer's disease and mild cognitive impairment, reduced retinal perfusion was frequently reported, data of patients with frontotemporal dementia (FTD) are lacking. Retinal and optic nerve head perfusion was evaluated in patients with FTD with OCT-A. Quantitative OCT-A metrics were analyzed and correlated with clinical markers and vascular cerebral lesions in FTD patients. OCT-A was performed in 18 eyes of 18 patients with FTD and 18 eyes of 18 healthy participants using RTVue XR Avanti with AngioVue. In addition, patients underwent a detailed ophthalmological, neurological, and neuropsychological examination, cerebral magnetic resonance imaging (MRI), and lumbar puncture. The flow density in the optic nerve head (ONH) and in the superficial capillary plexus (SCP) of the macula of patients was significantly lower compared to that of healthy controls (p < 0.001). Similarly, the VD in the deep capillary plexus (DCP) of the macula of patients was significantly lower compared to that of healthy controls (p < 0.001). There was no significant correlation between the flow density data, white matter lesions in brain MRI, cognitive deficits, and cerebrospinal fluid markers of dementia. Patients with FTD showed a reduced flow density in the ONH, and in the superficial and deep retinal capillary plexus of the macula, when compared with that of healthy controls. Quantitative analyses of retinal perfusion using OCT-A may therefore help in the diagnosis and monitoring of FTD. Larger and longitudinal studies are necessary to evaluate if OCT-A is a suitable biomarker for patients with FTD.

Non-invasive assessment of sublingual microcirculation using flow derived from green light PPG: evaluation and reference values.

The study of sublingual microcirculation offers valuable insights into vascular changes and overcomes some limitations of peripheral microcirculation assessment. Videomicroscopy and pulse oximetry have been used to assess microcirculation, providing insights into organ perfusion beyond macrohemodynamics parameters. However, both techniques have important limitations that preclude their use in clinical practice. To address this, we propose a non-invasive approach using photoplethysmography (PPG) to assess microcirculation. Two experiments were performed on different samples of 31 subjects. First, multi-wavelength, finger PPG signals were compared before and while applying pressure on the sensor to determine if PPG signals could detect changes in peripheral microcirculation. For the second experiment, PPG signals were acquired from the ventral region of the tongue, aiming to assess the microcirculation through features calculated from the PPG signal and its first derivative. In experiment 1, 13 out of 15 features extracted from green PPG signals showed significant differences () before and while pressure was applied to the sensor, suggesting that green light could detect flow distortion in superficial capillaries. In experiment 2, 15 features showed potential application of PPG signal for sublingual microcirculation assessment. The PPG signal and its first derivative have the potential to effectively assess microcirculation when measured from the fingertip and the tongue. The assessment of sublingual microcirculation was done through the extraction of 15 features from the green PPG signal and its first derivative. Future studies are needed to standardize and gain a deeper understanding of the evaluated features.

Association between functional parameter and structural, and vascular parameters in advanced glaucoma

Aims/Purpose: We aimed to evaluate the function‐vasculature, and function–structure relationships in advanced glaucoma patients.Methods: This cross‐sectional study included 29 eyes of 24 advanced glaucoma patients. Advanced glaucoma was classified as visual fields (VFs) with a mean deviation (MD) below ‐12 dB according to Hodapp‐Parrish‐Anderson classification system. The structural parameters, cup/disc area ratio, cup/disc vertical ratio, cup/disc horizontal ratio, rim area, disc area, cup volume, retinal nerve fibre layer thickness, macular ganglion cell complex (GCC) thickness, were measured using optical coherence tomography (OCT, Optovue, Fremont, CA). The vessel density of superficial retinal capillary plexus (SRCP), deep retinal capillary plexus (DRCP), outer retina (OR), and choriocapillaris (CC) were analysed by optical coherence tomography angiography (OCTA, DRI OCT Triton Plus, Topcon, Tokyo, Japan). For all layers, the average vessel density of the area between 1 mm and 3 mm diameter circles was calculated, assuming the 1 mm diameter area centered on the fovea as the central region. Relationships between 10–2 VF MD values, and structural and vascular parameters were assessed by Pearson's correlation coefficients. p &lt; 0.05 was considered statistically significant.Results: The mean ± SD age of all patients was 61.9 ± 15.8 years and 75% were male. For structural parameters, there was a positive correlation between the MD and GCC thickness values (p = 0.001, r = 0.617), while none of the parameters of the optic disc were related to the MD value. There were significant positive correlations with the vessel densities of the SRCP and CC layers (p = 0.001, r = 0.593 and p = 0.002, r = 0.541, respectively).Conclusions: Decreased vessel densities of the SRCP and CC were significantly associated with severity of visual field damage. This study showed that OCTA can be a promising method in daily use for monitoring advanced glaucoma.

Four years follow‐up OCTA changes in long‐term type 1 diabetic patients without diabetic retinopathy

Aims/Purpose: To assess changes in retinal capillary plexuses and choriocapillaris over 4 years' time in long‐term Type 1 diabetic patients (DM1) without diabetic retinopathy (DR).Methods: Twenty‐four eyes of 24 long‐term DM1 patients with no DR lesions were examined by optical coherence tomography angiography (OCTA) over a 4 year follow‐up period. Vascular density (VD) of both superficial and deep retinal capillary plexuses (SCP, DCP) and choriocapillaris (CC) were compared, as well as foveal avascular zone (FAZ) area and diameters.Results: Mean age was 46.84 ± 11.28 years and the average DM1 evolution time was 28.88 ± 8.04 years. Mean HbA1c level was 7.34 ± 0.94% at the last examination. SCP showed a statistically significant increase in VD in all areas except the inferior quadrant. There were no changes in the area or diameters of the FAZ in the SCP. In the DCP, there was a significant increase in VD in the temporal quadrant and a decrease in the inferior quadrant, along with a decrease in the horizontal diameter of the FAZ. The nasal area of the CC showed a significant increase in VD.Conclusions: DM1 patients present changes in the inner retina microvascularization after a follow‐up period of 4 years before displaying any signs of DR, mainly an increase in VD the SCP of the retina, along with a decrease in VD in the inferior quadrant of the DCP.

Differential response of macular and disc capillaries in response to the orthostatic hypotension test

Aims/Purpose: To investigate the effect of the orthostatic hypotension test on the macular and disc capillaries, in subjects with different blood pressure (BP) status.Methods: We prospectively recruited ophthalmologically healthy subjects (age 50–65) from a large‐scale population‐based Dutch cohort. We allocated participants to four groups: low BP, normal BP, treated high BP, and untreated high BP. We obtained two 6x6 mm macular and two 6x6 mm disc OCTA scans of the superficial capillaries. After lying for 5 min, participants stood up for 3 min, following which third scans were obtained from both regions. We quantified vessel density (VD) using customized software. We used linear mixed models to compare VD among groups before and after the orthostatic hypotension test.Results: We included 98 eyes from 98 subjects for the macular scans and 95 for the disc scans. Parafoveal VD was similar between groups (p = 0.65) and increased following the orthostatic hypotension test (40.4%, 40.6% pre‐test and 40.7% post‐test; p = 0.002). Post hoc analysis revealed that this difference was only significant between the first and third scan (p = 0.001). Peripapillary VD remained unchanged pre‐ and post‐test (p = 0.61), but differed between groups (low BP: 44.0%, normal BP: 45.0%, treated high BP: 44.1%, untreated high BP: 44.5%; p = 0.022). Post hoc analysis revealed that these differences were significant between normotensives and subjects with low BP (p = 0.028) and borderline between normotensives and subjects with treated high BP (p = 0.072).Conclusions: We observed an autoregulatory response of macular, but not disc, capillaries, following BP drop due to the orthostatic hypotension test.

Optical Coherence Tomography Angiography in the Evaluation of Macular Retinal Microvasculature in Patients in the Early Clinical Stage of Alzheimer’s Disease – A Preliminary Report

IntroductionAlzheimer’s disease (AD) is a chronic neurodegenerative condition causing cognitive decline among elderly individuals. In addition to neurological deficits, a key role in the onset and subsequent progression of AD Alzheimer’s disease-specific changes is attributed to vascular factors. Retinal microvasculature and cerebral small vessels share similar anatomical features and physiological characteristics, and damage to the retinal vascular bed can be observed at any stage of AD Alzheimer’s disease. Retinal microvasculature can be visualized and assessed non-invasively using the technique of optical coherence tomography angiography (OCT-A).Aim of studyEvaluation of macular retinal microvasculature in the superficial capillary plexus based on OCT-A optical coherence tomography angiography images in patients diagnosed with the mild stage of Alzheimer’s dementia.Material and methodsThe study involved a total of 21 patients diagnosed with mild Alzheimer’s dementia confirmed by neuropsychological tests and neuroimaging studies. optical coherence tomography angiography OCT-A was used to determine vessel density in the superficial retinal capillary plexus (SRCP), i.e. generate a density map within five-field ETDRS circles with diameters of 3 mm and 6 mm.ResultsAlterations in the macular retinal capillary network were noted in all eyes studied. In the majority of eyes, there was a marked reduction in vessel density reflected in the quantitative metrics in the density map around the FAZ in at least one of the scans obtained for a given eye (3 mm x 3 mm and/ or 6 mm x 6 mm) and in the macroscopic evaluation of the superficial and deep capillary plexuses, capillary thinning, and irregular area/mexpansion of the FAZ.ConclusionsOptical coherence tomography angiography OCT-A has the potential to serve as a valuable tool for screening or monitoring the response to therapies in patients with Alzheimer’s disease AD. However, further research is necessary to standardize study methodologies and determine whether impaired retinal microvasculature in patients with Alzheimer-type MCI or preclinical Alzheimer’s disease AD correlates with the advancement of cognitive decline and loss of neurons and cerebral blood vessels in individual Alzheimer’s disease AD patients and, hence, has clinical utility.

Topographic comparison of the retinal microvascular changes between patients with compressive and glaucomatous optic neuropathies

We investigated the difference in optical coherence tomography angiography characteristics between the patients with compressive optic neuropathy (CON, n = 26) and glaucomatous optic neuropathy (GON, n = 26), who were matched for the severity of visual field defect. The peripapillary retinal nerve fiber layer (pRNFL) thickness in the nasal and temporal sectors was thinner in the CON group, whereas the inferior pRNFL thickness was thinner in the GON group. Accordingly, the CON group had lower peripapillary vessel density (pVD) in the nasal and temporal sectors, and the GON group in the inferior sector. In the macular area, the CON group had a thinner macular ganglion cell-inner plexiform layer in the superior and nasal sectors, whereas the GON group in the inferior sector. However, the CON group did not have a lower macular VD than the GON group in any sector, whereas the GON group exhibited lower superficial capillary plexus VD in the superior, inferior, and temporal sectors. Comparison of the structure–vasculature correlation revealed a significant difference in the nasal and temporal peripapillary areas and superior and nasal macular sectors; a decrease in VD was greater in the GON group than in the CON group when the comparable structural change occurred.

32-year-old diabetic patient with progressive vision loss and crystalline retinopathy.

To report the case of severe bilateral retinal vascular occlusion in a patient with hyperoxalosis and chronic renal failure. Observational case report. Medical and imaging records were retrospectively reviewed. The patient was imaged with ultra-widefield (UWF) fundus photography and fluorescein angiography (UWF-FA), cross sectional and en face spectral-domain optical coherence tomography (SD-OCT), and OCT angiography. A 32-year-old diabetic patient receiving peritoneal dialysis was referred because of severe vision loss. UWF color fundus photography showed diffuse sclerotic retinal vessels and diffuse intraretinal crystals in both eyes. UWF-FA illustrated near-complete retinal vascular occlusion and capillary wipe out in both eyes. SD-OCT demonstrated diffuse inner and middle retina thinning in both eyes and multiple intraretinal hyperreflective foci consistent with crystalline deposits in all retina layers of both eyes. OCT angiography revealed severe capillary and large vessel non-perfusion in the superficial and deep retinal capillary plexus of each eye. The serum oxalate levels were increased at 28 µmol/L (reference range < 2 µmol/L) and genetic testing was positive for a heterozygous mutation of the AGXT (Alanine-Glyoxylate Amino Transferase) gene that causes type 1 autosomal recessive primary hyperoxaluria. A diagnosis of hyperoxalosis causing severe retinal vascular occlusion was rendered. Hyperoxalosis was the result of multiple factors including heterozygous AGXT mutation, chronic renal failure insufficiently treated with peritoneal dialysis, and a diet high in oxalate. This case highlights the importance of ruling out retinal oxalosis in patients on peritoneal dialysis in order to initiate prompt hemodialysis and prevent severe retinal vascular occlusion.

Intraretinal microvascular alterations in indirect traumatic optic neuropathy using optical coherence tomography angiography.

To quantitatively evaluate macular and peripapillary microvascular alterations in patients with indirect traumatic optic neuropathy (TON) compared to normal controls using optical coherence tomography angiography (OCT-A) and determine their associations with other ocular parameters. We enrolled 33 eyes of 33 patients with TON and 34 eyes of 34 healthy controls. OCT-A was used to generate microvascular structure images of the superficial retinal capillary plexus (SRCP), deep retinal capillary plexus (DRCP), and radial peripapillary capillary (RPC) segment in the macula and peripapillary area. Functional and structural parameters such as best-corrected visual acuity, visual field, peripapillary retinal nerve fibre layer (pRNFL) thickness, macular ganglion cell-inner plexiform layer (mGCIPL) thickness, OCT-A variables were compared between TON patients and controls. Age, gender, and spherical equivalent refractive errors were statistically adjusted for the analysis. OCT-A revealed a significant reduction of the average vessel density in the RPC segment in TON patients compared to controls (48.5% ± 6.28 vs. 57.88% ± 3.06%, P < 0.0001, corrected P < 0.0001). When comparing sectors, the vessel density of the RPC segment in TON patients was also significantly lower in all four quadrants compared to healthy controls. The inferior sector vessel density of the RPC segment was significantly associated with visual field defects (P = 0.0253) and visual acuity (P = 0.0369). The temporal sector vessel density of DRCP was also associated with visual field defects (P = 0.0377). The RPC segment in the superior and inferior sector vessel density displayed a significant association with the corresponding regional pRNFL thickness (P = 0.0248 and <0.0001, respectively). Patients with indirect TON exhibit significant microvascular alterations compared to controls. This study confirms that TON can induce intraretinal microvascular changes and suggests that OCT-A may serve as a useful biomarker for assessing visual functional and structural changes.

The prospects for early detection with optical coherence tomography (OCT) and OCT angiography in major depressive disorder

BackgroundResearch has shown the diagnostic potential of optical coherence tomography (OCT) and OCT angiography (OCTA) in various psychiatric disorders. However, there is few research focusing on changes specific to Major Depressive Disorder (MDD), and the diagnostic value of OCT combined with OCTA parameters for MDD remains unclear. MethodsIn this study, we investigated microvascular and morphology changes in the retina of MDD patients using a combination of OCTA and OCT parameters, and to examine their correlation with MDD mood and cognitive function in order to assess their diagnostic capability. ResultsOur findings revealed a significant decline in macular vessel density (MVD) in the superficial retinal capillary plexus (SRCP) across all subfields, except the NO area. We also observed a significant positive correlation between fovea and Stroop-1, as well as between temporal inner (TI) and Stroop-3 in MDD patients. Furthermore, we identified a negative correlation between fovea and Self-Rating Depression Scale, as well as between Superior outer (SO) and Difficulties in Emotion Regulation Scale-C in MDD patients. LimitationsThe sample size was small. Anatomical variables in blood flow may contribute to variability between subjects and outcomes. ConclusionsThe diagnostic value of OCTA suggests their potential as valuable tools for monitoring and diagnosing MDD.

In vivo structural and functional imaging of human nailbed microvasculature using photoacoustic microscopy.

Monitoring microvascular structure and function is of great significance for the diagnosis of many diseases. In this study, we demonstrate the feasibility of OR-PAM to nailbed microcirculation detection as a new, to the best of our knowledge, application scenario in humans. We propose a dual-wavelength optical-resolution photoacoustic microscopy (OR-PAM) with improved local-flexible coupling to image human nailbed microvasculature. Microchip lasers with 532 nm wavelength are employed as the pump sources. The 558 nm laser is generated from the 532 nm laser through the stimulated Raman scattering effect. The flowing water, circulated by a peristaltic pump, maintains the acoustic coupling between the ultrasonic transducer and the sample. These designs improve the sensitivity, practicality, and stability of the OR-PAM system for human in vivo experiments. The imaging of the mouse ear demonstrates the ability of our system to acquire structural and functional information. Then, the system is applied to image human nailbed microvasculature. The imaging results reveal that the superficial capillaries are arranged in a straight sagittal pattern, approximately parallel to the long axis of the finger. The arterial and venular limbs are distinguished according to their oxygen saturation differences. Additionally, the images successfully discover the capillary loops with single or multiple twists, the oxygen release at the end of the capillary loop, and the changes when the nailbed is abnormal.

Hemoporfin-mediated photodynamic therapy for angiokeratoma corporis diffusum: A case report

SignificanceAngiokeratoma corporis diffusum (ACD) is one type of angiokeratomas which are characterized on histology by superficial dilated capillaries with epidermal proliferation. ACD seriously influences patients’ appearance and quality of life. Many therapies have been used to solved this problem. However, all the treatments have not been proved very effective. Hemoporfin-mediated photodynamic therapy (Hemoporfin-PDT) was considered recently as a promising treatment for PWS according to the principle of targeted photodynamic destruction of the vascular wall of the lesion. Approach: approachA 27-year-old male patient diagnosed with angiokeratoma corporis diffusum (ACD) by skin tissue biopsy has undergone pulsed dye laser for times, but the result was unsatisfying. After evaluating and obtaining the patient's agreement, we utilized Hemoporfin-PDT with 530 nm LED green light to treat ACD. When followed up in the 1 year after 2 treatments, the patient was pleased with the efficacy that most red papules on his face disappeared. ResultsThe patient achieved great improvement after two treatments. ConclusionsHemoporfin-PDT could be used to treat ACD.

Retinal Vascular Density Using Optical Coherence Tomography-Angiography in Optic Neuritis.

This is a cross-sectional study including 22 patients with unilateral ON and 20 control eyes of healthy subjects. A complete clinical examination and OCT-A were performed at least 6 months after the acute episode of optic neuritis. Vascular plexuses of the peripapillary and perifoveolar images obtained from OCT-A were used to calculate the VD in each plexus: superficial, deep, and peripapillary capillaries for each group (ON eyes, fellow eyes, healthy eyes). Compared to healthy control eyes, in the peripapillary area, we found a significant decrease in VD not only in ON eyes but also in fellow eyes in average (p ≤ 0.05) and in the temporal sector (p < 0.001). In the perifoveolar area, the VD of the superficial capillary plexus is decreased in all sectors (p < 0.001) in ON eyes and only in the upper sector (p = 0.037) of fellow eyes compared to control eyes. VD correlates with ganglion cell layer (GCL) thickness in ON and in fellow eyes. Peripapillary vascular density is decreased in both affected eyes and fellow eyes after a unilateral episode of optic neuritis, suggesting a subclinical involvement of the disease. Further studies are needed to clarify the mechanism and clinical implications of these data.

OCT and OCT-A biomarkers in multiple sclerosis - review.

Objective: Retinal neuronal and vascular changes have been observed in multiple sclerosis (MS) patients. The aim of this review was to highlight the most current optical coherence tomography (OCT) and optical coherence tomography angiography (OCT-A) data in MS and to provide information about the possibility of using OCT / OCT-A parameters as biomarkers for screening, diagnosis and monitoring of MS. Methods: To carry out this review, a meticulous literature search was undergone on PubMed between 2014 and the present day, using the following terms: "multiple", "sclerosis", "optical", "coherence", "tomography" and "angiography". Additional studies were found via references, being chosen according to relevance. Results: Retinal nerve fiber layer (RNFL) and ganglion cell layer (GCL) were significantly lower in MS patients compared to controls, and correlated with clinical and paraclinical variables, such as visual function, disability, and magnetic resonance imaging (MRI). Retinal capillary plexuses could be higher, lower or the same, and the best OCT-A microvasculature parameter for the detection of MS was the superficial capillary plexus (SCP). The reduced retinal vessel density (VD) was correlated with the disability in MS. Conclusions: OCT and OCT-A parameters could improve the development of retinal biomarkers for screening, early diagnosis and monitoring the disease progression of MS, and they could improve the development of potential future therapies that could slow or stop the course of this incurable disease. Abbreviations: DCP = deep capillary plexus; EDSS = Expanded Disability Status Scale; GCC = ganglion cell complex; GCL = ganglion cell layer; MRI = magnetic resonance imaging; MS = Multiple sclerosis; OCT = optical coherence tomography; OCT-A = optical coherence tomography angiography; ON = optic neuritis; RNFL = retinal nerve fiber layer; SCP = superficial capillary plexus; VD = vessel density.

Microvascular changes in obese adults detected by Optical Coherence Tomography Angiography.

Aim: The aim of this prospective, controlled, non-randomized study was the comparison of the retinal microvascular parameters of obese and nonobese adults. Methods: 184 eyes of 92 subjects were separated to 3 groups. 68 eyes were in the normal weight group, with a body mass index between 18.5 and 24.5 kg/ m2, 60 eyes were in the overweight group, with a body mass index between 25-29.9 kg/ m2, and 56 eyes were in the obese group, with a body mass index ≥ 30 kg/ m2. All the volunteers were applied visual acuity, ocular motility testing, and slit lamp and mydriatic fundus examination. Optical Coherence Tomography Angiography (OCT-A) scanning was practiced with Optovue (Optovue, Inc; Fremont, CA) on a 6.00 x 6.00 mm macular region, in the central fovea. Results: 184 eyes of ninety-two patients were involved in this prospective study. The vessels' density (VD) in the optic nerve head (ONH) were significantly lower in the overweight and obese adult volunteers compared to the normal weight control group. However, other OCTA parameters (including macular VDs, Foveal avascular zone (FAZ), choriocapillaris plexus (CCP) area) did not demonstrate any significant difference between groups. Subfoveal choroidal thickness (SCT) was higher in the overweight and obese patients when compared to the normal weight control group. Central macular thickness (CMT) did not reveal any significant difference between groups. Conclusion: Even though clinicians are limited in pointing out any differential findings in obese patients only by fundus examination, OCT-A provides a predictable view of the microvascular changes in the retina and choroid in obese patients. Abbreviations: BMI = Body mass index, WHO = World Health Organization, AMD = Age-related macular degeneration, CT = Choroidal thickness, OCTA = Optical Coherence Tomography Angiography, (W/H) ratio = Waist-hip ratio, ETDRS = Early Treatment Diabetic Retinopathy Study, VD = Vessel density, SCP = Superficial capillary plexus, DCP = Deep capillary plexus, CCP = Flow area of the choriocapillaris, FAZ = Avascular zone, CMT = Central macular thickness, ONH = Optic nerve head.

Prefrontal NIRS signal is unaffected by forehead Doppler flux during incremental cycling exercise.

Near-infrared spectroscopy (NIRS) is used to measure tissue concentrations of oxyhemoglobin (O2 Hb) and deoxyhemoglobin (HHb). In the context of exercise, NIRS confers a higher signal-to-noise ratio than other neuroimaging techniques. However, part of the signal may be influenced by thermoregulatory hyperemia in the superficial cutaneous capillaries of the forehead. The degree to which NIRS signals during exercise reflect cerebral or extracerebral hemodynamic changes is a continuing source of controversy. However, the influence of skin blood flow may be attenuated depending on the NIRS technique (e.g., frequency domain machines with maximal optode separation distances >3.5 cm). The purpose of this study was to compare the changes in forehead skin blood flow and cerebral hemoglobin concentration during incremental exercise versus direct vasodilation of the forehead skin induced by gradual local heating. Thirty participants (12 females, 18 males; age: 20.8 ± 3.2 years; body mass index: 23.8 ± 3.7 kg·m-2 ) participated in the study. Forehead skin blood flow was quantified laser Doppler flux and absolute concentrations of cerebral O2 Hb and HHb were measured by NIRS. Local heating significantly increased the Doppler flux signal across time and these changes were significantly correlated with skin temperature. During incremental exercise, skin temperature, Doppler flux, O2 Hband HHb increased however, the only significant change that was consistently correlated with Doppler flux was skin temperature. Therefore, a significant change in forehead skin blood flow may not significantly the NIRS hemoglobin data, depending on the type of NIRS device used.

Clinical and multimodal imaging features of acute macular neuroretinopathy lesions following recent SARS-CoV-2 infection.

To describe the clinical characteristics of eyes using multimodal imaging features with acute macular neuroretinopathy (AMN) lesions following severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection. Retrospective case series study. From December 18, 2022 to February 14, 2023, previously healthy cases within 1-week infection with SARS-CoV-2 and examined at Tianjin Eye Hospital to confirm the diagnosis of AMN were included in the study. Totally 5 males and 9 females [mean age: 29.93±10.32 (16-49)y] were presented for reduced vision, with or without blurred vision. All patients underwent best corrected visual acuity (BCVA), intraocular pressure, slit lamp microscopy, indirect fundoscopy. Simultaneously, multimodal imagings fundus photography (45° or 200° field of view) was performed in 7 cases (14 eyes). Near infrared (NIR) fundus photography was performed in 9 cases (18 eyes), optical coherence tomography (OCT) in 5 cases (10 eyes), optical coherence tomography angiography (OCTA) in 9 cases (18 eyes), and fundus fluorescence angiography (FFA) in 3 cases (6 eyes). Visual field was performed in 1 case (2 eyes). Multimodal imaging findings data from 14 patients with AMN were reviewed. All eyes demonstrated different extent hyperreflective lesions at the level of the inner nuclear layer and/or outer plexus layer on OCT or OCTA. Fundus photography (45° or 200° field of view) showed irregular hypo-reflective lesion around the fovea in 7 cases (14 eyes). OCTA demonstrated that the superficial retinal capillary plexus (SCP) vascular density, deep capillary plexus (DCP) vascular density and choriocapillaris (CC) vascular density was reduced in 9 case (18 eyes). Among the follow-up cases (2 cases), vascular density increased in 1 case with elevated BCVA; another case has vascular density decrease in one eye and basically unchanged in other eye. En face images of the ellipsoidal zone and interdigitation zone injury showed a low wedge-shaped reflection contour appearance. NIR image mainly show the absence of the outer retinal interdigitation zone in AMN. No abnormal fluorescence was observed in FFA. Corresponding partial defect of the visual field were visualized via perimeter in one case. The morbidity of SARS-CoV-2 infection with AMN is increased. Ophthalmologists should be aware of the possible, albeit rare, AMN after SARS-CoV-2 infection and focus on multimodal imaging features. OCT, OCTA, and infrared fundus phase are proved to be valuable tools for detection of AMN in patients with SARS-CoV-2.

Value of optical coherence tomography angiography for the assessment of visual functions in children with retinopathy of prematurity

AIM: To compare and assess morphometric, structural, and microvascular parameters of the macular zone in children with cicatricial ROP grades IIII with different visual acuity from those in healthy peers.&#x0D; MATERIAL AND METHODS: Eighteen children (36 eyes) aged 818 years with cicatricial ROP grades IIII were examined. Ten peers (20 eyes) made up the control group. All children, in addition to the standard ophthalmological examination, underwent optical coherence tomography and optical coherence tomography with angiography (OCTA). The diagnosis was carried out on a tomograph RS-3000 Advance 2 (Nidek (Japan)). In the resulting 33 mm scans with a center in the fovea, the vascular and perfusion density of the superficial retinal capillary plexus (SCP), deep retinal capillary plexus (DSP), and the foveolar avascular zone, were measured, the thickness of the retina in the fovea was evaluated, and the structure of the neuroepithelium in the macula was assessed.&#x0D; RESULTS: In children born before 27 weeks, the central retinal thickness was higher than that in more mature children (231.818.2 and 208.215.2 m, respectively), and the relationship of this parameter with visual acuity was not explored. The vascular density of SCP in children with ROP and best-corrected visual acuity (BCVA) up to 0.4 and more than 0.4 were 1.46 mm-1 and 1.35 mm-1, respectively; and in the control group, it was 1.89 mm-1.&#x0D; The perfusion densities of the SCP in these groups were 9.2%, 10.03%, and 13.3%, respectively. The vascular densities of the Deep capillary plexus (DCP) in children with ROP with BCVA up to 0.4 and more than 0.4 were 2.8 mm-1 and 3.0 mm-1, respectively; in the control group, it was 3.2 mm-1, and the perfusion density of the deep capillary plexus (DCP) in indicated groups were 25.7%, 30.9%, and 31.7%, respectively.&#x0D; CONCLUSION: The analysis of the architectonics of the retinal vascular bed in children with ROP using OCTA makes it possible to assess the relationship between microcirculation disorders in the central zone of the retina and visual acuity, which is of great scientific and practical importance.

Results of monitoring diabetic retinopathy in patients after simultaneous pancreas and kidney transplantation

BACKGROUND: Very few studies have focused on the state of the fundus and visual functions before and after simultaneous transplantation of the pancreas and kidney. In addition, the results and conclusions of authors on this topic are contradictory. AIMS: To evaluate the ophthalmological status of patients with diabetic retinopathy before and after kidney and pancreas transplantation. MATERIALS AND METHODS: The patients were divided into three groups: group 1 included patients on the transplant waiting list receiving hemodialysis, group 2 were kidney transplant recipients, and group 3 included patients who had undergone simultaneous pancreas and kidney transplantation. The ophthalmological status of patients was assessed through standard ophthalmic diagnostic methods and measurements of photosensitivity, central retinal thickness, choroid thickness, density perfusion of the superficial and deep retinal capillary plexus, choriocapillary layer, and deep choroidal layer in the foveal and parafoveal zones of the macular region. RESULTS: The study involved 76 patients (152 eyes) (group 1, n=30 patients undergoing dialysis; group 2, n=24 kidney transplant recipients; group 3, n=22 kidney and pancreaticoduodenal post-transplant recipients). Signs of the active phase of the proliferative stage of diabetic retinopathy (group 1, 54.1%; group 2, 53.3%; and group 3, 25.9%, p 0.05) and diabetic macular edema (group 1, 26.4%; group 2, 31.8%; and group 3, 12.8%, p 0.05) were more common in groups 1 and 2 than in group 3. Moreover, group 3 needed laser therapy (group 1, 45.3%; group 2, 43.2%; and group 3, 20.5%, p 0.05) and antiangiogenic therapy to a lesser extent (group 1, 18.9%; group 2, 25.0%; and group 3, 5.1%, p 0.05) than patients undergoing dialysis and kidney recipients. The eyes of patients after simultaneous pancreas and kidney transplantation were characterized by the smallest retinal thickness, highest retinal and choroidal perfusion, and highest visual acuity and photosensitivity (p 0.05). CONCLUSIONS: A surgical method for restoring euglycemia through transplantation of physiologically active pancreatic tissue favorably affects the morphological and histological state of the retina and retinal and choroidal hemoperfusion and reduces the frequency of the active phase of proliferative diabetic retinopathy and diabetic macular edema.