Repeatability of retinal and choroidal optical coherence tomography angiography indices in healthy children and young adults.

PURPOSE: To evaluate the repeatability of retinal and choroidal optical coherence tomography angiography (OCT-A) indices among healthy children and compare it to healthy young adults. METHODS: This prospective study captured 3 mm × 3 mm and 6 mm × 6 mm macular OCT-A scans including superficial and deep retinal layers, choriocapillaris and deep choroid over two visits, 1 week apart at approximately the same time of day, for 22 healthy adults (18-30 years) and 21 children (6-15 years). Magnification and projection-artefact corrected indices extracted using a custom image analysis program and individual biometry were compared between visits using Bland-Altman analysis and intraclass correlation (ICC). Retinal indices included foveal avascular zone metrics, perfusion and vessel density and choroidal indices included choriocapillaris flow deficit metrics and deep choroid perfusion density, in the foveal, parafoveal and perifoveal regions. Repeatability between adults and children was compared with F-test. RESULTS: Bland-Altman analysis showed that the mean differences between repeated OCT-A indices were not significantly different from zero for either of the zones, layers and scan sizes in the two age groups (p > 0.05) except for foveal vessel density and foveal avascular zone perimeter (p = 0.04 for both) of 6-mm-deep retinal layer scans. The ICC ranged between 0.67 and 0.99. Significantly higher variability between visits (p < 0.05) in the indices was noted among adults than children, especially for choroidal indices of larger scan size. CONCLUSION: The retinal and choroidal OCT-A indices in the foveal, parafoveal and perifoveal zones were repeatable in healthy children except for the foveal vessel density and foveal avascular zone perimeter of the 6-mm-deep retinal layer, which exhibited statistically borderline differences between visits. The adult group showed more variability between visits compared to children, especially in the larger scan size for choroidal OCT-A indices.

Feature-Based Classification of Mild Cognitive Impairment and Alzheimer's Disease Based on Optical Coherence Tomographic Angiographic Image.

Alzheimer's disease is a type of neurodegenerative disorder that is characterized by the progressive degeneration of brain cells, leading to cognitive decline and memory loss. It is the most common cause of dementia and affects millions of people worldwide. While there is currently no cure for Alzheimer's disease, early detection and treatment can help to slow the progression of symptoms and improve quality of life. This research presents a diagnostic tool for classifying mild cognitive impairment and Alzheimer's diseases using feature-based machine learning applied to optical coherence tomographic angiography images (OCT-A). Several features are extracted from the OCT-A image, including vessel density in five sectors, the area of the foveal avascular zone, retinal thickness, and novel features based on the histogram of the range-filtered OCT-A image. To ensure effectiveness for a diverse population, a large local database for our study was collected. The promising results of our study, with the best accuracy of 92.17,% will provide an efficient diagnostic tool for early detection of Alzheimer's disease.

Genetic Linkage between CAPN5 and TYR Variants in the Context of Albinism and Autosomal Dominant Neovascular Inflammatory Vitreoretinopathy Absence: A Case Report.

We present a case involving a patient whose clinical phenotype aligns with oculocutaneous albinism (OCA), yet exhibits a complex genotype primarily characterized by variants of unknown significance (VUS). An 11-year-old boy manifested iris hypopigmentation and translucency, pronounced photophobia, diminished visual acuity and stereopsis, nystagmus, reduced pigmentation of the retina, and foveal hypoplasia. Genetic testing was performed. A heterozygous missense VUS CAPN5 c.230A>G, p.(Gln77Arg), a heterozygous missense VUS TYR c.1307G>C, p.(Gly436Ala), and a heterozygous missense variant TYR c.1205G>A, p.(Arg402Gln) which was classified as a risk factor, were identified. We hypothesized that the TYR c.1307G>C, p.(Gly436Ala) variant is in genetic disequilibrium with the TYR c.1205G>A, p.(Arg402Gln) variant leading to deficient expression of melanogenic enzymes in retinal cells, resulting in the manifestation of mild OCA. Additionally, this study represents the case where we did not detect chiasmal misrouting in visual evoked potentials, nor did we observe a shift in the distribution of ganglion cell thickness from a temporal to a central position. Moreover, our patient's case supports the probable benign nature of the CAPN5 c.230A>G, p.(Gln77Arg) variant.

Optical coherence tomography angiography measurements in multiple sclerosis: a systematic review and meta-analysis.

BACKGROUND AND OBJECTIVES: Recent literature on multiple sclerosis (MS) demonstrates the growing implementation of optical coherence tomography-angiography (OCT-A) to discover potential qualitative and quantitative changes in the retina and optic nerve. In this review, we analyze OCT-A studies in patients with MS and examine its utility as a surrogate or precursor to changes in central nervous system tissue. METHODS: PubMed and EMBASE were systematically searched to identify articles that applied OCT-A to evaluate the retinal microvasculature measurements in patients with MS. Quantitative data synthesis was performed on all measurements which were evaluated in at least two unique studies with the same OCT-A devices, software, and study population compared to controls. A fixed-effects or random-effects model was applied for the meta-analysis based on the heterogeneity level. RESULTS: The study selection process yielded the inclusion of 18 studies with a total of 1552 evaluated eyes in 673 MS-associated optic neuritis (MSON) eyes, 741 MS without optic neuritis (MSNON eyes), and 138 eyes without specification for the presence of optic neuritis (ON) in addition to 1107 healthy control (HC) eyes. Results indicated that MS cases had significantly decreased whole image superficial capillary plexus (SCP) vessel density when compared to healthy control subjects in the analyses conducted on Optovue and Topcon studies (both P < 0.0001). Likewise, the whole image vessel densities of deep capillary plexus (DCP) and radial peripapillary capillary (RPC) were significantly lower in MS cases compared to HC (all P < 0.05). Regarding optic disc area quadrants, MSON eyes had significantly decreased mean RPC vessel density compared to MSNON eyes in all quadrants except for the inferior (all P < 0.05). Results of the analysis of studies that used prototype Axsun machine revealed that MSON and MSNON eyes both had significantly lower ONH flow index compared to HC (both P < 0.0001). CONCLUSIONS: This systematic review and meta-analysis of the studies reporting OCT-A measurements of people with MS confirmed the tendency of MS eyes to exhibit reduced vessel density in the macular and optic disc areas, mainly in SCP, DCP, and RPC vessel densities.

Comparison between open-angle glaucoma and angle-closure glaucoma regarding the short-term optic disc vessel density changes after trabeculectomy.

To compare the microvasculature of the optic disc in open-angle glaucoma (OAG) and angle-closure glaucoma (ACG) after trabeculectomy. This study included 34 patients divided into two groups based on the angle: (1) the OAG Group, which included 24 eyes from 24 patients, and (2) the ACG Group, which included ten eyes from 10 patients. All patients were subjected to comprehensive ophthalmic examinations. It included best-corrected visual acuity (BCVA), Goldmann applanation tonometry, gonioscopy, slit-lamp biomicroscopy, dilated fundus examination, and stereoscopic examination of the optic disc. The central corneal thickness was measured using a Nidek AL scan optical biometer. The visual field was evaluated by standard automated perimetry using Humphrey Field Analyzer (24-2 Swedish interactive threshold algorithm; Carl-Zeiss Meditec, Dublin, CA). Moreover, optical coherence tomography angiography (OCT-A) was performed utilizing the RTVue XR Avanti scanner (Optovue Inc., Fremont, CA, USA) preoperatively as well as 1 month after surgery. There was a statistically significant increase in optic disc vessel density (VD) in the whole image, radial peripapillary, inferior, superior, temporal, and nasal quadrant in OAG after surgery. Regarding the change in VD after surgery in ACG patients, there was a statistically significant increase in optic disc VD in the whole image, radial peripapillary, inferior, superior, temporal, and nasal quadrant in ACG after surgery.Regarding the percentage of VD change following trabeculectomy surgery, there were highly significant differences between the two groups for the whole image, radial peripapillary, inferior quadrant, and temporal quadrant VD. Statistically significant changes were also observed in the superior and nasal quadrants of VD. However, no significant change in VD was detected within the disc. In conclusion, the optic disc VD improved after the reduction of intraocular pressure (IOP) by surgery in both OAG and ACG. However, ACG demonstrated a significant improvement than the OAG.

Correlation of the OCT Double-Layer Sign with Type 1 Non-Exudative Neovascularization on OCT-A in Age-Related Macular Degeneration.

Background and Objectives: Early diagnosis of the exudative form of age-related macular degeneration (AMD) is very important for a timely first treatment, which is directly related to the preservation of functional visual acuity over a long period. The goal of this paper was to examine the correlation between the double-layer sign (DLS) and the presence of non-exudative macular neovascularization (MNV). Materials and Methods: Our research included 60 patients with AMD, exudative in one eye and non-exudative in the other eye. We analyzed only the non-exudative form using optical coherence tomography (OCT) and optical coherence tomography angiography (OCT-A). The patients were classified into three groups, depending on the duration of the disease (<2 years, 2 to 5 years, >5 years). The onset of the disease was deemed the moment of establishing a diagnosis of exudative AMD in one eye. We defined the presence or absence of a DLS using OCT and the presence of non-exudative MNV using OCT-A, both on 3 × 3 mm and 6 × 6 mm sections. DLS was used as a projection biomarker for non-exudative MNV, with the aim of establishing a rapid diagnosis and achieving early treatment of the disease. Results: We found that there was a statistically significant correlation between the DLS diagnosed using OCT and non-exudative MNV diagnosed by OCT-A for both 3 × 3 mm (p < 0.001) and 6 × 6 mm (p < 0.001) imaging. There was a statistically significant difference between the frequencies of both DLS and MNV in Groups I and III on both 3 × 3 and 6 × 6 mm imaging. A statistically significant difference was also noted in the frequencies of DLS and MNV on 6 × 6 mm imaging, but not on 3 × 3 mm imaging, between Groups I and II. No differences were found between the frequencies of DLS and MNV between Groups II and III. Conclusions: The DLS on OCT can be used as a projection biomarker to assess the presence of a non-exudative MNV.

Assessment of retinal and choroidal vessel density and nerve fibre layer thickness changes after orbitotomy in patients with severe non-active thyroid orbitopathy: a prospective study.

PURPOSE: To evaluate the optical coherence tomography angiogram changes in non-active severe thyroid-related ophthalmopathy patients after cosmetic bone decompression. METHODS: Eighteen patients (25 eyes) with severe not active not compressive (NANC) TED who were candidates for decompression surgery for cosmetic reasons were included in this study, and a 3 × 3 mm macular scan was used to measure vessel density and RNFL thickness. Whole macular vessel density in its superficial, deep and choriocapillaris layers was evaluated. The following data were extracted for each of layers: superior and inferior hemispheres, fovea, parafoveal vessel density, its superior and inferior hemispheres, and temporal, superior, nasal and inferior quadrant. RESULTS: The mean RPC increased postoperatively, which was statistically significant in small vessels of peripapillary area (p-value = 0.045). The mean RNFL thickness decreased after surgery and it was statistically significant in the peripapillary (p-value = 0.032) and Inferior-Hemifield area (p-value = 0.036). The choriocapillaris changes were significant in Superior-Hemifield (p-value = 0.031) and Fovea (p-value = 0.03). CONCLUSION: Thyroid-associated orbitopathy patients have a tendency to decrease vascular density and correlated with disease activity more than stage of orbitopathy. There was not a strong and even discrepant result in linkage of RNFL thickness and other optic nerve function tests and TED patient status and it is needed to do studies with more epidemiologic power and same methodology of study to be more comparable.

Retinal microvasculature and vasoreactivity changes in hypertension using optical coherence tomography-angiography.

PURPOSE: To evaluate the retinal vasculature and vasoreactivity of patients with hypertension (HTN) using spectral domain optical coherence tomography angiography (SD-OCTA). METHODS: Patients with and without a diagnosis of HTN were included in this cross-sectional observational study. All eyes were imaged with SD-OCTA using 3 mm × 3 mm and 6 mm × 6 mm centered on both the fovea and optic disk. A second 6 mm × 6 mm scan was taken after a 30 s breath-hold. Vessel density (VD), vessel skeletonized density (VSD), and fractal dimension (FD) were calculated using customized MATLAB scripts. Vessel diameter index (VDI) was obtained by taking the ratio of VD to VSD. Vasoreactivity was measured by subtracting the VD or VSD before and after breath-hold (∆VD, ∆VSD). RESULTS: Twenty-three eyes with HTN (17 patients) and 17 control eyes (15 patients) were included. In the 6 mm × 6 mm angiogram centered on fovea, the superficial capillary plexus (SCP) VD (ß = - 0.029, p = 0.012), VSD (ß = - 0.004, p = 0.043) and the choriocapillaris VD (ß = - 0.021, p = 0.030) were significantly decreased in HTN compared to control eyes. Similarly, FD was decreased in both the SCP (ß = - 0.012, p = 0.013) and choriocapillaris (ß = - 0.009, p = 0.030). In the 3 mm × 3 mm angiogram centered on optic disk, SCP VDI (ß = - 0.364, p = 0.034) was decreased. ∆VD and ∆VSD were both reduced in the DCP (ß = - 0.034, p = 0.032; ß = - 0.013, p = 0.043) and ∆VSD was elevated in the choriocapillaris of HTN eyes (ß = 0.004, p = 0.032). CONCLUSIONS: The study used SD-OCTA to show significant differences in the retinal vasculature of hypertensive patients. It was also the first to demonstrate the potential of OCT-A to investigate retinal vascular reactivity in patients with HTN.

Diagnosis and Treatment of Primary Inflammatory Choriocapillaropathies (PICCPs): A Comprehensive Overview.

PURPOSE: Primary inflammatory choriocapillaropathies (PICCPs) belong to a group of intraocular inflammatory diseases with the common characteristic of inflammatory choriocapillaris hypo- or non-perfusion as the main clinicopathological mechanism. The purpose of our article is to describe clinical characteristics and multimodal imaging, that can help the diagnosis and treatment of PICCPs. METHODS: Narrative review with multimodal imaging analysis. RESULTS: Choriocapillaris non-perfusion can affect the end-choriocappilaries, at the benign end of the PICCP spectrum (MEWDS), to larger choriocapillaris vessels or precapillary vessels at the origin of more severe forms such as acute posterior multifocal placoid pigment epitheliopathy (APMPPE), idiopathic multifocal choroiditis (MFC) and Serpiginous Choroiditis (SC). Diagnosis is mostly based on multimodal imaging and especially on indocyanine green angiography (ICGA), fundus autofluorescence (FAF) and spectral-domain optical coherence tomography (SD-OCT)/OCT-angiography (OCT-A). ICGA shows the typical pattern of patchy lobular hypofluorescence reflecting hypo- or non-perfusion of the choriocapillaris that can also take the aspect of geographic areas in the more severe forms. Treatment depends on the severity of the disease and goes from observation in MEWDS and some mild cases of APMPPE, to oral corticosteroid and/or immunomodulator agents in the more severe conditions of APMPPE and MFC and SC cases. Close multimodal monitoring is crucial in order to introduce or adjust treatment. CONCLUSION: PICCPs are resulting from one common clinicopathological mechanism, inflammatory choriocapillaris hypo- or non-perfusion. ICGA findings are essential for the diagnosis and follow-up of PICCPs, but non-invasive methods such as FAF and SD-OCT/OCT-A also have their role especially in follow-up of the diseases. Treatment should be individualized according to the pathology and the evolution of lesions.

Optical coherence tomography angiography of the macular microcirculation in acute primary angle closure treated with phacoemulsification.

PURPOSE: To measure the changes of macular microcirculation in cases with unilateral acute primary angle closure (APAC) who were managed by phacoemulsification. METHODS: Patients with unilateral APAC and managed by phacoemulsification were enrolled. The contralateral unaffected eyes were served as fellow group, and normal individuals were recruited as control group. Optical coherence tomography angiography (OCT-A) was performed to analyze the macular whole image vessel density (wiVD) and parafoveal vessel density (pfVD). The retinal nerve fiber layer (RNFL) and ganglion cell complex (GCC) thicknesses were assessed using spectral-domain optical coherence tomography. RESULTS: A total of 36 APAC patients and 35 eyes from 35 normal individuals were recruited. In the APAC eyes, the mean wiVD (42.1% ± 3.7%) and pfVD (45.2% ± 3.8%) in the superficial layers (wiVD-SL and pfVD-SL) were both significantly reduced, compared to fellow eyes (45.7% ± 3.1%, 48.7% ± 3.1%) and control eyes (44.4% ± 4.7%, 47.4% ± 5.1%) (P < 0.05). They were all statistically correlated with RNFL, GCC, visual field pattern standard deviation (PSD), and mean deviation (MD). CONCLUSION: The macular OCT-A parameters including wiVD-SL and pfVD-SL were significantly reduced in the eyes with APAC compared to the fellow unaffected eyes and normal control eyes. They were correlated well with RNFL, GCC, PSD and MD. The macular vessel density parameters may help monitor the progression of APAC.

[The role of optical coherence tomography angiography in the assessment of retinal microcirculation in thrombotic microangiopathy associated with malignant arterial hypertension]. / Rol' opticheskoi kogerentnoi tomografii s funktsiei angiografii v otsenke retinal'noi mikrotsirkulyatsii pri tromboticheskoi mikroangiopatii, assotsiirovannoi so zlokachestvennoi arterial'noi gipertenziei.

Optical coherence tomography angiography (OCT-A) allows detailed assessment of the state of local blood flow in various systemic ischemic diseases, which include thrombotic microangiopathy (TMA) associated with malignant arterial hypertension (MAH). PURPOSE: To evaluate retinal microcirculation using OCT-A imaging data in the group of patients with TMA associated with MAH. MATERIAL AND METHODS: The study consisted of a qualitative and quantitative analysis of OCT-A data from 7 patients (14 eyes) with TMA associated with MAH and verified by renal biopsy. The control group included 7 healthy individuals (14 eyes). The following parameters were analyzed: area size of the foveal avascular zone FAZ, mm, vessel density (VD, %) and vessel skeleton density (VSD, %). The indicators were measured separately in the deep and superficial vascular plexuses and divided by localization into: the total density of the entire measured area, central density, density by quadrants (superior, inferior, nasal and temporal). All quadrants were subdivided into inner (corresponding to parafovea) and outer (corresponding to perifovea). RESULTS: Local foci of vascular attenuation of the deep retinal capillary plexus, pathological tortuosity of blood vessels in the deep and superficial retinal capillary plexuses were found in 100% of study group patients. Per-quadrant analysis of OCT-A finding in the macular zone revealed a statistically significant decrease in VD of the deep retinal capillary plexus (p<0.05). A direct correlation was found between glomerular filtration rate and the VD index in the outer inferior (r=0.567; p=0.034) and inner temporal quadrants (r=0.613; p=0.020) of the deep retinal capillary plexus, as well as the level of hemoglobin in blood serum and VD in inner temporal quadrant of the deep vascular plexus (r=0.596; p=0.025). CONCLUSION: Changes revealed with OCT-A are the symptoms of TMA in MAH patients spreading to the retinal microvasculature, mainly at the level of the deep retinal capillary plexus.

[Biomarkers of retinal ischemia in thrombotic microangiopathy associated with malignant arterial hypertension on optical coherence tomography]. / Markery retinal'noi ishemii pri tromboticheskoi mikroangiopatii, assotsiirovannoi so zlokachestvennoi arterial'noi gipertenziei, po dannym opticheskoi kogerentnoi tomografii.

Malignant arterial hypertension is a clinical syndrome characterized by severe diastolic arterial hypertension with signs of ischemic damage to various organs. In some malignant arterial hypertension cases, thrombotic microangiopathy occurs - a rare life-threatening condition characterized by multiple systemic thrombosis of the microvasculature, including in the eyes, which can be clarified by optical scanning of the retina. PURPOSE: To determine markers of retinal ischemia in the eyes with thrombotic microangiopathy associated with malignant arterial hypertension. MATERIAL AND METHODS: The study included 6 patients (12 eyes) with thrombotic microangiopathy associated with malignant arterial hypertension who were examined by optical coherence tomography (OCT) and OCT angiography (OCT-A). All patients suffered from renal dysfunction, which etiology was determined by renal biopsy verifying the presence of renal thrombotic microangiopathy in all cases. RESULTS: According to OCT findings, there were bilateral local foci of thinning of the inner nuclear layer with elevation of the outer plexiform and outer nuclear layers of the retina in 5 out of 6 patients (83%). OCT-A revealed that in most cases (67%), these changes had perivascular localization and corresponded to the areas of attenuation of the deep capillary plexus. A statistically significant thinning of the inner nuclear layer of the retina was found in thrombotic microangiopathy associated with malignant arterial hypertension in comparison with the control group. CONCLUSION: Presence of renal thrombotic microangiopathy confirmed by renal biopsy and the anatomical similarity of the microvasculature of the kidneys and the eyes, give basis to consider the foci of «chronic¼ paracentral acute middle maculopathy detected with OCT in patients with malignant arterial hypertension as biomarkers of thrombotic microangiopathy of the eye.

Diabetic Macular Edema: State of Art and Intraocular Pharmacological Approaches.

Diabetic macular edema (DME) is the main cause of vision loss in diabetic retinopathy (DR). Although it is one of the main complications of diabetes, the pathogenesis of DME is not completely understood. The hyperglycemic state promotes the activation of multiple interlinked pathways leading to DME. Different classifications have been proposed: based on clinical features, on pathogenesis or on diagnostic tests (optical coherence tomography - OCT and fluorescin angiography - FA). The multimodal imaging allows a better analysis of the morphological features of the DME. Indeed, new inflammatory biomarkers have been identified on OCT. Also, several studies are evaluating the role of the morphological features, identified on multimodal imaging, to find new prognostic factors. Over the past decade, great progresses have been made in the management of DME. Therapeutic alternatives include intraocular injection of anti-vascular endothelial grow factor agents (anti-VEGF) and steroid molecules, focal/grid laser photocoagulation and vitreo-retinal surgery. This review is focused on the description and analysis of the current intravitreal therapeutic pharmacological strategies. Current guidelines recommend anti-VEGF as first line therapy in DME. Corticosteroids are becoming increasingly relevant blocking the inflammatory cascade and indirectly reducing VEGF synthesis.

Post-operative optical coherence tomography angiography features of chorioretinal folds resulting from pleomorphic adenoma of the lacrimal gland (PALG) of orbit- a case report.

BACKGROUND: Chorioretinal fold (CFs) is a rare condition resulting from undulations in the choriocapillaris, Bruch's membrane, retinal pigment epithelium and occasionally neurosensory retina. It can be idiopathic or due to different etiologies. The use of spectral-domain optical coherence tomography (SD-OCT) has increased the diagnosis of CFs and helped in differentiation from other etiologies. Recently, optical coherence tomography angiography (OCT-A) emerged as a non-invasive imaging technique allowing visualization of the individual layers of microvasculature of the retina and the choroid by comparing consecutive B-scans. We described a rare case of pleomorphic adenoma of the lacrimal gland (PALG) causing hyperopic shift and CFs with the new OCT-A technology, getting deeper insight into vascular changes of this disease. CASE PRESENTATION: A 40-year-old Asian man experienced progressive blurred vision in his right eye over 6 months. The patient's initial axial lengths were 25.55 mm in the right eye and 28.13 mm in the left eye. Fundus examination in the right eye revealed oblique CFs as well as the SD-OCT displayed. Magnetic resonance imaging showed intraconal mass extended from superior temporal side of the right orbit. The patient then received tumor removal surgery through lateral orbitotomy and histopathology confirmed a pleomorphic adenoma of the orbit. The patient had regular follow-up for 1 year. His best corrected visual acuity markedly improved from 20/50 to 20/20 with nearly stationary AXL. We performed OCT-A at one year after the surgery, which showed early visualization of deep choroidal vessels. The scleral remodeling due to mass effect of retrobulbar tumor also caused displacement of the deep large choroidal vessels over the superior macular area even after tumor removal. CONCLUSIONS: We reported a rare case of PALG with hyperopic shift and CFs as initial presentation. Surgical removal of the tumor partially resolved the CFs and contributes to impressive visual acuity recovery. The use of OCT-A provided a deeper insight to vascular architecture changes resulting from scleral remodeling after long-term tumor compression.

[Current trends in the screening for diabetic retinopathy]. / Sovremennye tendentsii skrininga diabeticheskoi retinopatii.

The incidence of diabetes in the world is steadily increasing, and so is growing the number of cases of vision loss and blindness resulting from diabetic retinopathy (DR). This pathology is asymptomatic in the initial stages, but only the early treatment can be effective. In this regard, DR screening is an important and actual problem. This article reviews the principles, criteria, and problems of the currently run DR screening programs that are based on digital photography of the fundus. Special attention is paid to the displayed biomarkers and their role in DR screening. Various research methods are described, such as fluorescence angiography, optical coherence tomography, optical coherence tomography agniography, laser scanning ophthalmoscopy, which can be used to visualize pathological changes in the retina associated with DR. These changes were considered as potential screening biomarkers for DR. The review also describes new areas of screening based on telemedicine, artificial intelligence, and mobile photo-registering devices.

[Swept source optical coherence tomography: a technology review]. / 'Swept source' - opticheskaia kogerentnaia tomografiia: obzor tekhnologii.

The article reviews the concept of swept source optical coherence tomography (SS-OCT) and presents a brief history of the technology, its implementation in modern commercial tomography, the advantages and disadvantages of the method.

Age and gender influence on foveal avascular zone in healthy eyes.

The foveal avascular zone (FAZ) is the capillary-free area in the central macula with high photoreceptor density and metabolic activity. In the present study we measured the superficial and deep macular foveal avascular zone (sFAZ, dFAZ) in the eyes of healthy adults of both sexes of various ages ranging from 10 to 69 years using optical coherence tomography angiography (OCT-A) in order to evaluate the influence of gender and age on FAZ size. A cross-sectional study was carried out in 240 eyes of 120 healthy subjects, OCT-A was performed by means of a Topcon swept source OCT. sFAZ and dFAZ areas were measured using the IMAGEnet6 software package. Subjects were grouped by age (six groups) and gender. The mean ±â€¯sd age of the subjects was 39.2 ±â€¯17.4 years (50% women, 50% men), ranging from 10 to 69 years. The overall mean sFAZ size in women (0.297 ±â€¯0.110 mm2) was significantly larger (p = 0.002) than in men (0.254 ±â€¯0.098 mm2). Similarly, the overall mean dFAZ in women (0.322 ±â€¯0.111 mm2) was significantly larger (p < 0.001) than in men (0.273 ±â€¯0.099). However, when analyzed by age group, these gender differences appeared only in groups younger than 20 years old and older than 50 years old. Men did not show differences among the six age groups. In women, for both sFAZ and dFAZ, the 20-29 year old group had a smaller FAZ size than the 50-59 year old group. In conclusion for both sFAZ and dFAZ, women have larger areas than men, but this occurs only in the young and old age groups. In men, age does not seem to influence the size of the FAZ, but in women, both sFAZ and dFAZ were significantly smaller in younger than in older ages. These results suggest that retinal changes in retinal structure caused by aging may be different in woman than in men, probably reflecting the more hormonal variations known to exist with age in women.

Comparison of vascular parameters between normal cynomolgus macaques and healthy humans by optical coherence tomography angiography.

BACKGROUND: The metabolic activity of retina is higher than other human tissues and is crucial to the vision. Cynomolgus macaques is widely used in ophthalmic disease research. The evaluation and comparison of macular and optic disc vascular circulation parameters between normal adult cynomolgus macaques and healthy adult humans using OCT-A can promote better use of nonhuman primate models in studies of ophthalmic vascular disease. METHODS: Twelve normal adult cynomolgus macaques with a mean age of 4.91 ± 0.43 years were studied for data collection. The macula of 28 adult healthy humans (14 males and 14 females), with a mean age of 25.11 ± 6.21 years and the optic discs of 9 adult healthy humans (4 males and 5 females) with a mean age of 28.56 ± 6.78 years were measured. The vessel density (VD) was measured using an RTVue XR with AngioVue. The scan sizes of the macular and optic discs were 3 × 3 mm and 4.5 × 4.5 mm, respectively. RESULTS: OCT-A can image the superficial and deep capillary plexuses and radial peripapillary capillary network. In RPC layer of the optic disc, the VD in the nasal quadrant was lower than the VD in the inferior temporal quadrant. Similarities and significant differences in VD between healthy humans and cynomolgus macaques were obtained using OCT-A. CONCLUSIONS: This study provides normal vascular parameters for adult cynomolgus macaques using OCT-A to help establish an optical parameter database for cynomolgus macaques and compare VD between healthy humans and cynomolgus macaques to promote choroid-retinopathy research. TRIAL REGISTRATION: Current Controlled Trials NCT03692169 , retrospectively registered on 26 sept 2018.

The diagnostic value of optical coherence tomography angiography in diabetic retinopathy: a systematic review.

PURPOSE: Diabetic retinopathy (DR) is one of the leading causes of blindness worldwide. Accurate investigative tools are essential for the early diagnosis and monitoring of the disease. Optical coherence tomography angiography (OCTA) is a recently developed technology that enables visualisation of the retinal microvasculature. METHODS: A systematic review of the literature was performed to examine the diagnostic use of OCTA in DR to date. Medline, EMBASE, and Cochrane databases were searched to find relevant studies. Sixty-one original studies were selected for the review. RESULTS AND DISCUSSION: OCTA has demonstrated the ability to identify microvascular features of DR such as microaneurysms, neovascularisation, and capillary non-perfusion. Furthermore, OCTA is enabling quantitative evaluation of the microvasculature of diabetic eyes. It has demonstrated the ability to detect early microvascular changes, in eyes with or without clinically evident DR. It has also been shown to detect progressive changes in the foveal avascular zone, and vascular perfusion density, with worsening severity of disease. It provides three-dimensional visualisation of the individual retinal vascular networks and is thereby enhancing our understanding of the role of the deeper vasculature in the pathogenesis of diabetic retinopathy and maculopathy. CONCLUSION: However, limitations exist with current OCTA technology, in respect to the small field of view, image quality, projection artefact, and inaccuracies in analysis of the deeper vascular layers. While questions remain regarding its practical applicability in its present form, with continuing development and improvement of the technology, the diagnostic value of OCTA in diabetic retinopathy is likely to become evident.

Principles of OCTA and Applications in Clinical Neurology.

PURPOSE OF REVIEW: The article reviews the recent findings on the use of optical coherence tomography angiography (OCTA) in neurology. RECENT FINDINGS: OCTA is a new addition to the powerful and complementary technology of the OCT. Due to its noninvasiveness, and reproducibility, it is possible to obtain high-resolution 3D images of the vessels of the human eye. As the vessels of the retina with the presence of endothelial cell's tight junctions resemble the brain vessels, it was hypothesized that the imaging of the retinal vessels might bring insight into brain vessels. OCTA has been effectively used to predict retinal vessel abnormalities in dementia, demyelization, optic disc neuropathies, and inherited degenerative diseases. Most common findings were decrease of vascular density and flow and an increase of avascular zones. Although OCTA is a relative new technology, recent studies show that it can be successfully applied in neurology.