Optical Coherence Tomography Angiography Imaging in Inherited Retinal Diseases

Retinal vascular abnormalities in myotonic dystrophy assessed by optical coherence tomography angiography - Cross-sectional study

BACKGROUND

The aim of the study was to detect the changes in retinal and choroidal vasculature via optical coherence tomography angiography (OCTA) by comparing the quantitative OCTA parameters in patients with and without myotonic dystrophies (DM).

MATERIAL

The cross-sectional study. Forty-one consecutive patients affected by DMs were enrolled. The inclusion criteria were molecular diagnosis of DM types 1 and 2. To avoid the age effect on microvascular changes and to justify a comparison between DM1 and DM2 patients, two control groups matched for sex and age were established.

RESULTS

The vascular density was found to be significantly decreased in the DM groups compared to the controls in the macular, parafoveal and perifoveal zone of superficial capillary plexus (p < 0.001 for the DM1 group, and p = 0.001, p = 0.005 and p = 0.026, respectively, for the DM2 group), as well as in the macular zone in the deep capillary plexus for DM1 (p = 0.002) and deep macular and perifoveal zone for DM2 (p = 0.007, p = 0.001, respectively). The foveal avascular zone showed no significant differences between DM1 and DM2 compared to their control groups (p = 0.320 and p = 0.945, respectively).

CONCLUSION

Our results show that DM is associated not only with the classic pigmentary changes but also with superficial and deep retinal microvasculature abnormalities, suggesting that these changes may be related to local hypoperfusion. Optical coherence tomography angiography is a useful tool for the diagnosis and characterization of retinal changes in DM and should be part of the standard evaluation of these patients.

Recent Progress in Photoreceptor Cell-Based Therapy for Degenerative Retinal Disease

Age-related macular degeneration and retinitis pigmentosa are degenerative retinal diseases that cause severe vision loss. Early clinical trials involving transplantation of photoreceptors as treatment for these conditions are underway. In this review, we summarize recent progress in the field of photoreceptor transplantation, including some pertinent results regarding photoreceptor manufacture, photoreceptor transplantation, mechanisms of donor-host cell integration such as material transfer and photoreceptor transplant immunology. We conclude by proposing several approaches that may provide a rational basis for selecting a vision restoration strategy (eg, donor-host synapse formation vs donor-host nanotube formation) and improved transplant efficiency.

Artificial intelligence and hemodynamic studies in optical coherence tomography angiography for diabetic retinopathy evaluation: A review

Diabetic retinopathy (DR) is a rapidly emerging retinal abnormality worldwide, which can cause significant vision loss by disrupting the vascular structure in the retina. Recently, optical coherence tomography angiography (OCTA) has emerged as an effective imaging tool for diagnosing and monitoring DR. OCTA produces high-quality 3-dimensional images and provides deeper visualization of retinal vessel capillaries and plexuses. The clinical relevance of OCTA in detecting, classifying, and planning therapeutic procedures for DR patients has been highlighted in various studies. Quantitative indicators obtained from OCTA, such as blood vessel segmentation of the retina, foveal avascular zone (FAZ) extraction, retinal blood vessel density, blood velocity, flow rate, capillary vessel pressure, and retinal oxygen extraction, have been identified as crucial hemodynamic features for screening DR using computer-aided systems in artificial intelligence (AI). AI has the potential to assist physicians and ophthalmologists in developing new treatment options. In this review, we explore how OCTA has impacted the future of DR screening and early diagnosis. It also focuses on how analysis methods have evolved over time in clinical trials. The future of OCTA imaging and its continued use in AI-assisted analysis is promising and will undoubtedly enhance the clinical management of DR.

IMI-Management and Investigation of High Myopia in Infants and Young Children

Purpose

The purpose of this study was to evaluate the epidemiology, etiology, clinical assessment, investigation, management, and visual consequences of high myopia (≤-6 diopters [D]) in infants and young children.

Findings

High myopia is rare in pre-school children with a prevalence less than 1%. The etiology of myopia in such children is different than in older children, with a high rate of secondary myopia associated with prematurity or genetic causes. The priority following the diagnosis of high myopia in childhood is to determine whether there is an associated medical diagnosis that may be of greater overall importance to the health of the child through a clinical evaluation that targets the commonest features associated with syndromic forms of myopia. Biometric evaluation (including axial length and corneal curvature) is important to distinguishing axial myopia from refractive myopia associated with abnormal development of the anterior segment. Additional investigation includes ocular imaging, electrophysiological tests, genetic testing, and involvement of pediatricians and clinical geneticists is often warranted. Following investigation, optical correction is essential, but this may be more challenging and complex than in older children. Application of myopia control interventions in this group of children requires a case-by-case approach due to the lack of evidence of efficacy and clinical heterogeneity of high myopia in young children.

Conclusions

High myopia in infants and young children is a rare condition with a different pattern of etiology to that seen in older children. The clinical management of such children, in terms of investigation, optical correction, and use of myopia control treatments, is a complex and often multidisciplinary process.

Volume-rendered optical coherence tomography angiography during ocular interventions: Advocating for noninvasive intraoperative retinal perfusion monitoring

We aimed to test for feasibility of volume-rendered optical coherence tomography angiography (OCTA) as a novel method for assessing/quantifying retinal vasculature during ocular procedures and to explore the potential for intraoperative use. Thirty patients undergoing periocular anaesthesia were enrolled, since published evidence suggests a reduction in ocular blood flow. Retinal perfusion was monitored based on planar OCTA image-derived data provided by a standard quantification algorithm and postprocessed/volume-rendered OCTA data using a custom software script. Overall, imaging procedures were successful, yet imaging artifacts occurred frequently. In interventional eyes, perfusion parameters decreased during anaesthesia. Planar image-derived and volume rendering-derived parameters were correlated. No correlation was found between perfusion parameters and a motion artifact score developed for this study, yet all perfusion parameters correlated with signal strength as displayed by the device. Concluding, volume-rendered OCTA allows for noninvasive three-dimensional retinal vasculature assessment/quantification in challenging surgical settings and appears generally feasible for intraoperative use.

Modern diagnostic and therapeutic approaches in familial maculopathy with reference to North Carolina macular dystrophy

AIMS

We present a familial hereditary macular dystrophy, resembling North Carolina Macular Dystrophy. In members of a family, we describe the development of diagnostic-therapeutic approaches and their impact on the prognosis of those whose vision was affected.

METHODS

The macular dystrophy of varying degrees of severity was diagnosed in 3 consecutive generations in different family members, both men and women. Modern therapeutic tools were used for the diagnostics. In one patient of the youngest generation, the development of secondary choroidal neovascularization (CNV) was identified and treated with an anti-VEGF (vascular endothelial growth factor) agent. DNA was isolated from venous blood and genome sequencing was performed in a proband.

RESULTS

We analysed the data of 13 members of one family of three consecutive generations. Six of them had macular dystrophy. The first were two of three siblings, a woman (73 years old) and a man (67). The offspring of the afflicted man, a female (36) and a male (80), had maculopathy. The first daughter of the woman (12) revealed findings of maculopathy but with normal electrical activity of the retina. The second girl (18), developed secondary CNV which responded well to intravitreal anti-VEGF treatment. Genetic analysis excluded mutations previously reported to be pathogenic for NCMD.

CONCLUSION

If there is a maculopathy of unclear etiology in younger patients or in patients with unclear development or appearance, it is advisable to focus carefully on the family history and trace the occurrence of impaired vision in other family members.

Retinal Vascular Plexuses Are Unequally Affected in Canine Inherited Retinal Degenerations

Purpose

To characterize the progression of vascular changes that occur in each retinal plexus, in three canine models of inherited retinal degeneration.

Methods

In this retrospective cohort study, we examined the retinal imaging records of 44 dogs from a research colony that had undergone optical coherence tomography angiography (OCTA) imaging. Animals enrolled included crd2/NPHP5 and xlpra2/RPGR mutant dogs imaged at different stages of photoreceptor loss, as well as RHO^T4R/+ dogs after acute light-induced rod degeneration. Also included were normal controls imaged at similar ages. OCT angiograms of the superficial vascular plexus combined with the intermediate capillary plexus (SVP + ICP), and the deep capillary plexus (DCP) were analyzed using the AngioTool software to calculate vessel density and other vascular parameters.

Results

A reduction in vessel density was seen over time in both the SVP + ICP and DCP in all mutant dogs but was more pronounced in the DCP. Scans were subclassified based on outer nuclear layer (ONL) thinning compared to age-matched normal controls. When ONL loss was 0% to 50%, vessel density in the DCP was significantly lower than in age-matched controls. In all cases, when ONL loss exceeded 87.5%, vessel density in the SVP + ICP was significantly reduced as well. In the acute light-induced rod degeneration model, the vascular regression changes were observed mainly in the DCP.

Conclusions

Vessel density reduction in dogs undergoing retinal degeneration is first detected by OCTA in the DCP, and only at later stages in the SVP + ICP.

Optical coherence tomography angiography in retinitis pigmentosa: A narrative review

Retinitis pigmentosa (RP) is a group of inherited retinal disorders characterized by progressive rod and cone photoreceptor degeneration. Changes in retinal vasculature have long been associated with RP. Optical coherence tomography angiography (OCTA) is a novel imaging technology that enables noninvasive visualization of the retinal and choroidal microvasculature. OCTA enables quantification of microvascular changes in the retinal capillary plexus and choriocapillaris, in addition to qualitative feature description. Therefore, OCTA has the potential to become an important tool for better understanding, early detection, progression, and treatment of RP. In this review, we focus on the applications of OCTA in clinical research on RP. We also discuss future improvements in the OCTA technology for RP management. We believe that the advancement of the OCTA technique will ultimately lead to a better understanding of RP and aid in the prevention of visual impairment.

Optical Coherence Tomography Angiography for the Evaluation of Retinal and Choroidal Vasculature in Retinitis Pigmentosa: A Monocentric Experience

Purpose: We investigated the chorioretinal microvascular changes in patients with retinitis pigmentosa (RP) by optical coherence tomography angiography (OCTA). Methods: Twenty-six patients (52 eyes) affected by RP were compared with 19 healthy controls (38 eyes). OCTA 3 mm × 3 mm macular scans were performed in all subjects. We evaluated the vessel density (VD) of the superficial capillary plexus (VD SCP), deep capillary plexus (VD DCP), choriocapillaris (VD CC), and choroid (VD choroid). We also evaluated the foveal avascular zone (FAZ) area, and the correlation between clinical and OCTA parameters. We also measured central retinal thickness (CRT) and subfoveal choroidal thickness (CT). Results: RP patients compared to healthy controls showed significantly lower VD SCP values (27.56% ± 15.37 vs. 49.39% ± 1.55; p-value < 0.0001), lower VD DCP values (38.43% ± 15.23 vs. 3.34% ± 0.26; p-value < 0.0001), lower VD CC values (46.02% ± 1.293 vs. 50.63% ± 0.4274; p-value = 0.0040), and lower VD choroid values (38.48% ± 15.23 vs. 3.34% ± 0.26; p-value < 0.0001). Even the FAZ area was significantly lower in RP patients (0.45 mm2 ± 0.35 vs. 0.26 mm2 ± 0.13; p-value < 0.0001). The FAZ area was larger with increasing age, both in control (r = 0.42; p = 0.012) and RP group (r = 0.46; p-value = 0.009). In RP patients, there was a statistically significant correlation between best-corrected visual acuity and VD SCP (r = 0.24, p-value = 0.04) and VD DCP (r = 0.52; p-value = 0.0004) and between subfoveal choroidal thickness and VD SCP (r = 0.43, p-value < 0.001) and VD DCP (r = 0.35, p-value < 0.001). Conclusions: In our study, OCTA reported relevant vascular alterations in RP patients in comparison with the healthy controls, in agreement with the published literature. These abnormalities were associated with choroidal atrophy and related to visual acuity loss. OCTA provided clinically significant information and may represent a reliable tool for the management of RP patients.

Imaging of the skin microvascularization using spatially depolarized dynamic speckle

SIGNIFICANCE

We propose a technique devoted to real-time high-resolution imaging of skin microvascularization.

AIM

The process utilizes the temporal variation of the spatially depolarized optical speckle field generated by moving red blood cells when illuminated with fully polarized coherent light.

APPROACH

Polarimetric filtering prevents the contribution of surface scattering from reaching the camera and thus favors the detection of multiscattered photons from the deeper layers of the skin.

RESULTS

Full-field images reveal the microvasculature with a spatial resolution of 80  μm. The acquisition speed allows for real-time applications.

CONCLUSIONS

We demonstrate the ability of this method to determine in 1 s a stable and reliable microvascular activity, enabling numerous clinical applications that require quantitative measurements.

Update of application of olfactory ensheathing cells and stem cells/exosomes in the treatment of retinal disorders

Age-related macular degeneration, diabetic retinopathy, retinitis pigmentosa and other retinal disorders are the main causes of visual impairment worldwide. In the past, these retinal diseases, especially dry age-related macular degeneration, proliferative diabetic retinopathy and retinitis pigmentosa, were treated with traditional surgery and drugs. However, the effect was moderate. In recent years, researchers have used embryonic stem cells, induced pluripotent stem cells, mesenchymal stem cells, olfactory ensheathing cells and other stem cells to conduct experiments and found that stem cells can inhibit inflammation, regulate immune response, secrete neurotrophic factors, and differentiate into retinal cells to replace and promote restoration of the damaged parts. These stem cells have the potential to treat retinal diseases. Whether it is in animal experiments or clinical trials, the increase in the number of retinal cells, maintenance of function and improvement of visual function all reflect the advanced of stem cells to treat retinal diseases, but its risk preserves the donor's hidden pathogenic genes, immune rejection and tumorigenicity. With the development of exosomes study, researchers have discovered that exosomes come from a wide range of sources and can be secreted by almost all types of cells. Using exosomes with stem cell to treat retinal diseases is more effective than using stem cells alone. This review article summarizes the recent advances in the application of olfactory ensheathing cells and stem cells/exosomes in the treatment of retinal disorders.

Optical coherence tomography angiography (OCT-A) in retinitis pigmentosa and macular dystrophy patients: a retrospective study

Purpose

To evaluate macular vascular abnormalities in patients with macular dystrophies (MD) and retinitis pigmentosa (RP) through application of optical coherence tomography angiography (OCT-A).

Methods

In this retrospective study, patients with MD and RP were examined by OCT-A and compared to healthy individuals. OCT-A images were analyzed regarding the diameter and surface area of the foveal avascular zone (FAZ) as well as flow (FL) in different retinal layers (superficial vascular complex (SVC), intermediate capillary complex (ICP), deep capillary complex (DCP), choriocapillaris (CC), and choroid (CD)).

Results

Twenty-one patients with MD, 21 patients with RP without macular edema (RPnE), 8 patients with RP with edema (RPwE), and 41 healthy individuals were enrolled. The group of MD and RPnE patients showed none or only minor changes in FAZ. In RPwE patients, the FAZ was significantly smaller in vertical and horizontal measurements and surface area in SVC, whereas it was markedly enlarged in ICP. FL was significantly reduced compared to healthy individuals by an average of 13.2% in CD, 14.2% in CC, and 8.4% in DCP in all patient groups. In ICP, the reduction was 9.2% for RPnE and 12.7% for RPwE patients. The SVC showed reduced FL in the MD (8.1%) and RPnE (10.3%) group.

Conclusions

OCT-A is a valuable tool to examine retinal vascular abnormalities in patients with MD and RP. OCT-A revealed a reduced flow in various retinal layers in MD, RPnE, and RPwE. Alterations of the FAZ were less distinct in these groups which add to the variation reported previously.

Retinal Vascular Abnormalities in Different Types of Inherited Retinal Dystrophies Assessed by Optical Coherence Tomography Angiography

Purpose:

To investigate the retinal vascular characteristics among patients with different types of inherited retinal dystrophies (IRDs).

Methods:

This comparative cross-sectional study was conducted on 59 genetically confirmed cases of IRD including 37 patients with retinitis pigmentosa (RP) (74 eyes), 13 patients with Stargardt disease (STGD) (26 eyes), and 9 patients with cone-rod dystrophy (CRD) (18 eyes). Both eyes of 50 age- and sex-matched healthy individuals were investigated as controls. All participants underwent optical coherence tomography angiography to investigate the vascular densities (VDs) of superficial and deep capillary plexus (SCP and DCP) as well as foveal avascular zone area.

Results:

In RP, significantly lower VD in whole image (P = 0.001 for DCP), fovea (P = 0.038 for SCP), parafovea (P < 0.001 for SCP and DCP), and perifovea (P < 0.001 for SCP and DCP) was observed compared to controls. In STGD, VD of parafovea (P = 0.012 for SCP and P = 0.001 for DCP) and fovea (P = 0.016 for DCP) was significantly lower than controls. In CRD, the VD of parafovea (P = 0.025 for DCP) was significantly lower than controls. Whole image density was significantly lower in RP compared to STGD (P < 0.001 for SCP) and CRD (P = 0.037 for SCP). VD in parafovea (P = 0.005 for SCP) and perifovea (P < 0.001 for SCP and DCP) regions was significantly lower in RP compared with STGD. Also, foveal VD in STGD was significantly lower than RP (P = 0.023 for DCP).

Conclusion:

Our study demonstrated lower VDs in three different IRDs including RP, STGD, and CRD compared to healthy controls. Changes were more dominant in RP patients.

An optometrist's guide to the top candidate inherited retinal diseases for gene therapy

This review presents the phenotypic and genotypic profiles of a select group of inherited retinal diseases (IRDs) that are currently the focus of retinal gene therapy trials globally. Research progress in IRD treatment trials may soon lead to their availability in Australia and New Zealand, as either approved treatment or a clinical trial. The salient clinical characteristics of retinitis pigmentosa-the largest IRD category-are highlighted, with specific reference to RPE65-associated Leber congenital amaurosis, followed by other specific IRDs, namely choroideremia and ABCA4-associated Stargardt disease. These IRDs are selected based on their candidacy for gene therapy. Guidance on the clinical diagnostic tests that support each of these diagnoses will be presented. More broadly, the most useful structure and function measures to monitor IRD progression is discussed, along with the key assessments that offer differential diagnostic insight. This review is intended to be a clinical guide for optometrists, to assist in assessment and management of individuals who may be eligible for current and future gene therapies. A companion article in this issue will provide an overview of the basic principles of gene therapy and its development as a new treatment for inherited retinal diseases.

Looking Ahead: Visual and Anatomical Endpoints in Future Trials of Diabetic Macular Ischemia

Diabetic macular ischemia (DMI) is a common complication of diabetic retinopathy that can lead to progressive and irreversible visual loss. Despite substantial clinical burden, there are no treatments for DMI, no validated clinical trial endpoints, and few clinical trials focusing on DMI. Therefore, generating consensus on validated endpoints that can be used in DMI for the development of effective interventions is vital. In this review, we discuss potential endpoints appropriate for use in clinical trials of DMI, and consider the data required to establish acceptable and meaningful endpoints. A combination of anatomical, functional, and patient-reported outcome measures will provide the most complete picture of changes that occur during the progression of DMI. Potential endpoint measures include change in size of the foveal avascular zone measured by optical coherence tomography angiography and change over time in best-corrected visual acuity. However, these endpoints must be supported by further research. We also recommend studies to investigate the natural history and progression of DMI. In addition to improving understanding of how patient demographics and comorbidities such as diabetic macular edema affect clinical trial endpoints, these studies would help to build the consensus definition of DMI that is currently missing from clinical practice and research.

Optical coherence tomography angiography findings in patients undergoing transcorneal electrical stimulation for treating retinitis pigmentosa

Purpose

Transcorneal electrical stimulation (TES) is a novel treatment approach for patients with retinitis pigmentosa (RP). The aim of our study was to observe changes in optical coherence tomography angiography (OCTA) that would be attributed to TES treatment.

Methods

A total of 73 eyes were included: 43 eyes of 22 subjects (11 ♀, 11 ♂) suffering from RP were examined at baseline (BL), after first stimulation (TS), 1 week (1W), and 6 months (6M) after treatment initiation and were compared with 30 control eyes of 15 subjects (8 ♀, 7 ♂). TES was performed simultaneously on both eyes for 30 min weekly. OCTA scans of 9 × 15 mm were recorded with a PLEX Elite 9000 swept-source OCTA device (Carl Zeiss Meditec AG, Jena). Vascular density metrics such as perfusion density (PD) and vessel density (VD) were calculated automatically for the macular area by using standardised extended early treatment diabetic retinopathy study (ETDRS) grids centred around the fovea. In addition, the capillary perfusion density (CPD) and the capillary flux index (CFI) of the peripapillary nerve fibre layer microvasculature in all four quadrants of an annulus centred at the optic disc were measured. All parameters were determined over all retinal layers and separately for the superficial (SCP) and deep capillary plexus (DCP). ANOVA-based linear mixed-effects models were calculated with SPSS®.

Results

Throughout the course of TES treatment, the macular VD and PD of all retinal layers in all subsections showed a slight decrement without reaching statistical significance, also when analysed separately in the SCP and DCP (p > 0.08). In analogy, the average CPD and CFI also presented with a slight decrement (p > 0.20). However, when compared with controls, most OCTA parameters showed a significant decrement (p < 0.05). When analysed systematically in all subsections of the extended ETDRS grid, the temporal macular subsections within the outer ring (radius 1.5–3 mm) and also of the peripheral C1, C2, and C3 rings (radius 3–7.5 mm) showed lower VD and PD values when compared with the other subsections (p < 0.05).

Conclusion

Vascular density metrics in the macular region and the peripapillary microvasculature appear to remain unaffected by continuous TES treatment within a period of 6 months.

Electronic supplementary material

The online version of this article (10.1007/s00417-020-04963-7) contains supplementary material, which is available to authorized users.

Analysis of optical coherence angiography in cystoid macular oedema associated with gyrate atrophy

BACKGROUND

To evaluate the relationship between superficial, deep foveal avascular zone (FAZ) and foveal cyst areas in eyes with cystoid macular oedema (CMO) associated with gyrate atrophy of the choroid and retina (GA).

METHODS

This is a retrospective collaborative multicenter study of optical coherence tomography-angiography (OCTA) images in GA. Superficial and deep FAZ and foveal cyst were measured using Image J by two independent experts. Values were corrected for myopia magnification. These values were compared with age-matched controls from normative data.

RESULTS

Twenty-three eyes from 12 patients with GA and CMO were included in the study. The mean ± standard deviation age was 22 ± 19.7 years, mean Snellen spectacle-corrected visual acuity of 20/70 with mean myopia of 5.7 ± 4.1 dioptres. Qualitatively, no focal occlusion of superficial and deep capillary plexus was noted. Mean superficial FAZ area (0.484 ± 0.317 mm²), deep FAZ area (0.626 ± 0.452 mm²), and foveal cyst area (0.630 ± 0.503 mm²) were significantly larger than superficial and deep FAZ areas in controls of same age range (p < 0.001). Macular cyst area correlated with superficial FAZ area (R = 0.59; p = 0.0057) and more strongly with deep FAZ area (R = 0.69; p < 0.001).

CONCLUSIONS

The superficial and deep FAZ area in GA-associated CMO were noted to be significantly larger than in controls. It seems that RPE dysfunction leads to foveal cyst enlargement displacing the capillary plexus with resultant enlarged superficial and deep FAZ area.