QUANTITATIVE ANALYSIS OF OPTICAL COHERENCE TOMOGRAPHY ANGIOGRAPHY IN ADULT-ONSET FOVEOMACULAR VITELLIFORM DYSTROPHY

Quantitative microvascular alterations in butterfly-shaped pattern dystrophy and adult-onset foveomacular vitelliform dystrophy

PURPOSE

To study retinal microvascular parameters in patients with butterfly-shaped pattern dystrophy (BPD) and adult foveomacular vitelliform dystrophy (AFVD).

METHODS

This case-control study included BPD and AFVD patients in a tertiary university hospital. Eyes with known ocular disease and prior ocular surgery other than uncomplicated cataract surgery were excluded. Right eyes of healthy individuals without systemic or ocular disease were included as controls. En face 6×6mm angiograms were obtained with the RTVue XR Avanti (Optovue, USA). We used the Kruskal-Wallis test to compare vessel density (VD) values of the retina, optic disc and foveal avascular zone (FAZ) between groups. Dunn-Bonferroni correction was used for pairwise comparisons.

RESULTS

Eighteen eyes of 10 BPD patients, 17 eyes of 9 AFVD patients, and 26 right eyes of 26 controls were included. Six patients in the BPD, 4 patients in the AFVD, and 16 patients in the control group were female. The groups did not differ by sex (P=0.650). AFVD patients were of higher mean age (64.3±7.8) than BPD patients (55.9±11.1) and controls (53.6±5.5) (P=0.008, p=0.009). In BPD (P=0.008, P=0.044) and AFVD (P=0.006, P=0.002), parafoveal and perifoveal vessel density (VD) of the superficial capillary plexus were lower than controls. Parafoveal VD of the deep capillary plexus in AFVD was lower than in controls (P=0.012). There was no difference in the foveal avascular area between groups (P=0.563). Optic discs parameters did not differ.

CONCLUSION

A comparable loss in vascular density may indicate shared pathophysiology or represent a common sign of impairment in retinal homeostasis. Further research is needed to clarify underlying microvascular pathogenetic mechanisms in pattern dystrophies.

Optical coherence tomography angiography in Bietti crystalline dystrophy

PURPOSE

Bietti crystalline dystrophy (BCD) is a rare autosomal recessive retinal dystrophy caused by pathogenic variants of CYP4V2 gene and characterized by shiny yellow deposits in the retina and progressive atrophy of the retinal pigment epithelium (RPE) and choriocapillaris. The main aim of the present study is to describe the optical coherence tomography angiography (OCTA) characteristics of a patient affected by BCD.

METHODS

A 59-years-old female with genetically confirmed BCD underwent an ophthalmological examination complete of OCTA performed in the atrophic retina, the junctional zone and the apparently normal retina. The area of choriocapillaris (CC) atrophy was compared to the area of RPE atrophy on fundus autofluorescence (FAF) imaging.

RESULTS

A severe vessel density (VD) deficit at the level of superficial and deep capillary plexa as well as CC was registered in atrophic areas, which resulted deeper with respect to the junctional area, whereas the apparently preserved retina revealed VD values similar to that of control eyes. The area of RPE atrophy on FAF was larger (55.90 mm2 in right eye and 48.76 mm2 in left eye) than the area of CC atrophy on OCTA imaging (51.86 mm2 and 42.44 mm2 respectively in right and left eye).

CONCLUSIONS

Our findings suggest that VD impairment of retinal plexa and CC follows the degeneration of RPE as demonstrated by the greater size of the area of RPE atrophy compared to CC atrophy. Further investigations based on OCTA imaging are necessary to enhance our knowledge of this rare disease.

Distribution of Neurofilament in Peeled Internal Limiting Membrane

BACKGROUND AND OBJECTIVE

The aim was to study the distribution of neurofilament in peeled internal limiting membrane (ILM).

PATIENTS AND METHODS

Prospective case study. Vitrectomy and ILM peeling were performed in patients with epiretinal membrane and macular hole. ILM flap specimens were obtained as one disc area size from five locations. Immunofluorescent staining was performed with an antineurofilament heavy antibody. Using a confocal microscope, retinal cell debris density was studied using the ImageJ program.

RESULTS

Percent of stained neurofilament was 1.58 ± 1.14% in total (2.45 ± 1.37% in extranasal, 1.97 ± 0.75% in extratemporal, 1.93 ± 1.26% in juxta-nasal, 0.89 ± 0.69% in fovea, and 0.63 ± 0.46% in juxtatemporal). The Kruskal-Wallis test revealed significant differences among groups (P < 0.05). Bonferroni post hoc analysis only confirmed significant difference between juxtatemporal and extranasal groups (P < 0.05).

CONCLUSIONS

In peeled ILM flap, neurofilaments are rarely detected in the juxtatemporal area. However, they are frequently detected in the extranasal area. [Ophthalmic Surg Lasers Imaging Retina 2023;54:643-648.].

OCT angiography and its retinal biomarkers [Invited]

Optical coherence tomography angiography (OCTA) is a high-resolution, depth-resolved imaging modality with important applications in ophthalmic practice. An extension of structural OCT, OCTA enables non-invasive, high-contrast imaging of retinal and choroidal vasculature that are amenable to quantification. As such, OCTA offers the capability to identify and characterize biomarkers important for clinical practice and therapeutic research. Here, we review new methods for analyzing biomarkers and discuss new insights provided by OCTA.

Adult-onset foveomacular vitelliform dystrophy: epidemiology, pathophysiology, imaging, and prognosis

Adult-onset foveomacular dystrophy (AOFVD) is a retinal pattern dystrophy that may affect up to 1 in 7,400 individuals. There is much that is unknown regarding this disease's epidemiology, risk factors for development, and rate of progression through its four stages. Advancements in retinal imaging over the past 15 years have enabled improved characterization of the different stages of AOFVD. These imaging advancements also offer new ways of differentiating AOFVD from phenotypically similar retinal diseases like age-related macular degeneration and Best disease. This review synthesizes the most recent discoveries regarding imaging correlates within AOFVD as well as risk factors for the development of AOFVD, complications of AOFVD, and treatment options. Our aim is to provide ophthalmologists a succinct resource so that they may offer clarity, guidance, and appropriate monitoring and treatments for their patients with suspected AOFVD.

PRPH2-Associated Retinopathy: Novel Variants and Genotype-Phenotype Correlations

PURPOSE

A broad spectrum of autosomal-dominant inherited retinal diseases (IRDs), ranging from mild macular pattern dystrophy to severe cone-rod degeneration, is associated with PRPH2 variants (peripherinopathies). We present detailed clinical and molecular characterization of patients affected by peripherinopathies, aiming to expand the mutational spectrum, and propose novel genotype-phenotype correlations.

DESIGN

Observational, retrospective case series.

PARTICIPANTS

Patients with an IRD related to a molecularly proven PRPH2 variant.

METHODS

Data from ophthalmic examinations and retinal imaging were collected for each follow-up visit. The standard imaging protocol included OCT, blue-light autofluorescence, near-infrared autofluorescence, and ultra-widefield fundus imaging. Genetic analysis was performed with a genomic approach by next-generation sequencing.

MAIN OUTCOME MEASURES

Results of ophthalmic examination, retinal imaging, and molecular genetic analysis.

RESULTS

Overall, a total of 19 patients with an IRD and a (likely) pathogenic PRPH2 variant were identified. Their age at presentation had a median of 48 years, whereas the symptomatic disease onset was in their 30s or 40s in 74% of cases. The median follow-up time was 4 years. Clinically, 6 patients were diagnosed with cone-rod dystrophy and 13 with pattern dystrophy. Among the 13 PRPH2 pathogenic variants identified in our cohort, 7 were missense, 3 nonsense, 2 frame shifting, and 1 splice site. Missense variants in the D2 loop were associated with cone-rod dystrophies and poor visual prognosis, whereas predicted loss-of-function alleles with pattern dystrophies and retention of a good visual function into adulthood. Overall, the following 7 variants were novel and never associated to a clinical phenotype: c.68delT, c.290G>A, c.413T>G, c.642C>G, c.702_706dupCAGTT, c.771_772delinsGA, and c.850C>G.

CONCLUSIONS

Here, we report the findings of a retrospective case series that provided a detailed clinical and molecular characterization of 19 patients harboring 13 different PRPH2 pathogenic variants, 7 of which were previously unreported, expanding the mutational spectrum of the PRPH2 gene. Loss-of-function variants might be preferentially associated with mild-pattern dystrophies, whereas missense dominant-negative variants might be preferentially associated with severely blinding cone-rod degenerations. Further studies are needed to better define the pathogenetic mechanisms and the functional effects of most variants to allow the development of successful gene therapy.

FINANCIAL DISCLOSURE(S)

Proprietary or commercial disclosure may be found after the references.

The role of OCT- angiography in predicting anatomical and functional recovery after endoscopic endonasal pituitary surgery: A 1-year longitudinal study

Purpose

The purpose of this study was to investigate the changes in structural spectral-domain optical coherence tomography (SD-OCT), OCT Angiography (OCTA) parameters, and visual acuity, 1 year after endoscopic endonasal approach for the removal of an intra-suprasellar pituitary adenoma compressing optic chiasm and compare outcomes with 48 hours postoperative data.

Methods

Sixteen eyes of eight patients (4 males, 4 females, mean age 52 ± 11 years) were enrolled in this prospective study. The primary outcome was to evaluate the changes over time before and after surgery, analyzing the Best Corrected Visual Acuity (BCVA), Ganglion Cell Complex (GCC), Retinal Nerve Fiber Layer (RNFL) thicknesses, the retinal vessel density (VD) of Superficial Capillary Plexus (SCP), Deep Capillary Plexus (DCP), Radial Peripapillary Capillary (RPC) and the Foveal Avascular Zone (FAZ). The secondary outcome was to identify potential biomarkers that could predict visual acuity changes after 1-year follow-up.

Results

When comparing SD-OCT and OCTA measurements obtained after 1 year with those observed 48 hours after surgery, GCC and RNFL were significantly improved. After a significant reduction at 48 hours, GCC thickness showed a significant increase at 1 year after surgery (p = 0.007), while a significant restoration of RNFL thickness was found at 1 year (p = 0.005), as well as the VD of SCP, DCP, and RPC values. FAZ area did not change over time. BCVA significantly improved at each time after surgery (p = 0.037, p = 0.013). A statistically significant correlation was found between the preoperative BCVA, VD of SCP, DCP, RPC, and the postoperative BCVA at 1 year (p = 0.017, p = 0.029, p = 0.031, p = 0.023).

Conclusion

SD-OCT and OCTA provide helpful information to identify the retinal structural and vascular improvements 1 year after surgery. OCTA parameters could serve as potential predictive markers for visual acuity recovery at long-term follow-up.

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.

Customized Slab-Segmentation Method for Projection-Artifact Elimination in Best Vitelliform Macular Dystrophy: A Swept-Source Optical Coherence Tomography Angiography Study

Purpose

To assess the efficacy of customized slab segmentation in eliminating projection artifacts in swept-source optical coherence tomography angiography (SS-OCTA) images of Best vitelliform macular dystrophy (BVMD).

Methods

Prospective case series including different stages of BVMD. We analyzed SS-OCTA images for flow signals in the outer retina and coregistered B-scan images for distortion of the segmentation slabs defining the outer retina. We applied a customized method for slab realignment whenever BVMD lesions produced distortion of the slabs. Afterward, we checked the images to determine whether the previously noted flow signal had persisted or disappeared, described as “true flow” or “pseudoflow”, respectively. Categorical variables were analyzed with X² or Fisher’s exact tests, while quantitative variables were analyzed with independent t-test at p<0.05.

Results

The study included 39 eyes of 22 patients. We detected BVMD patterns I (dome-shaped hyperreflective lesion without neurosensory retinal detachment), II (knob-like hyperreflective lesion with localized neurosensory retinal detachment), and III (heterogeneous scattered hyperreflective material) in 49%, 23%, and 28% of eyes, respectively. Pseudoflow was evident mostly in eyes with pattern II lesions, presence of flow signal within BVMD lesions, and lesions whose height represented >80% of the retinal thickness (p<0.001).

Conclusion

Customized slab segmentation is effective in eliminating projection artifact in SS-OCTA images of BVMD.

Summary

Projection artifact is a significant confounding factor in emerging SS-OCTA technology through production of pseudoflow signals that can lead to misinterpretation of images of BVMD lesions. The present study proposes a customized method for correction of segmentation errors to eliminate projection artifacts in SS-OCTA images of BVMD patients.

Early vascular modifications after endoscopic endonasal pituitary surgery: The role of OCT-angiography

PURPOSE

The aim of the present study is to analyze the changes in retinal vessel density (VD), using Optical Coherence Tomography Angiography (OCT-A), in patients that received endoscopic endonasal approach for the removal of an intra-suprasellar pituitary adenoma compressing optic chiasm.

METHODS

We evaluated the VD in Superficial Capillary Plexus (SCP), Deep Capillary Plexus (DCP), Radial Peripapillary Capillary (RPC) and the Foveal Avascular Zone (FAZ) area in a series of fourteen patients (7 males, 7 females, mean age 56 ± 13 years), as compared to healthy controls. We also detected the structural Spectral Domain (SD)-OCT parameters: Ganglion Cell Complex (GCC), Retinal Nerve Fiber Layer (RNFL), visual field parameters (Mean Deviation, Pattern Standard Deviation) and Best Corrected Visual Acuity (BCVA). These measurements were performed prior than surgery and 48 hours after.

RESULTS

The patients showed a significant decrease in VD of the macular and papillary regions, a significant increase in FAZ area, a significant impairment in SD-OCT, VF parameters and BCVA respect to 14 eyes of 14 healthy controls (p<0.05), at pre-op evaluation. In patients group the VD in SCP, DCP and RPC increased after surgery respect to baseline but the difference turned to be out statistically significant only in RPC (p = 0.003). Also the BCVA (p = 0.040) and the Mean Deviation at visual field (p = 0.015) significantly improved after surgery. While there was a reduction in structural OCT parameters but it was statistically significant only in GCC (p = 0.039). A positive correlation was found between the preoperative VD of the RPC, Mean Deviation, BCVA and the postoperative Mean Deviation (r = 0.426 p = 0.027; r = 0.624 p = 0.001; r = 0.515 p = 0.006).

CONCLUSION

OCT-A allows to detect the early changes occurring within 48 hours after surgery showing that the improvement in retinal vessel density could occur before the recovery of the structural OCT parameters and can be a positive predictive factor for the functional recovery.

Assessment of retinal vessel density in adult-onset foveomacular vitelliform dystrophy by optical coherence tomography angiography

BACKGROUND

To evaluate retinal thickness, area of foveal avascular zone (FAZ), flow area and flow density of choriocapillaris, vessel density of both superficial capillary plexus (SCP) and deep capillary plexus (DCP) of eyes with adult-onset foveomacular vitelliform dystrophy (AOFVD) using optical coherence tomography angiography (OCT-A) and compare the results with healthy controls.

METHODS

17 eyes of 14 patients diagnosed with AOFVD and 17 eyes of 17 healthy subjects were enrolled in this study. All patients underwent a complete ophthalmological examination and a 6 x 6 mm macular OCT-A scanning. Quantiative results of retinal thickness, retinal vessel density of SCP and DCP, FAZ area, flow area and flow density of choriocapillaris were analyzed.

RESULTS

No statistically significant differences were noted in the vessel density of the SCP, except for the parafoveal nasal sector (P = 0.048). Similarly, no statistically significant differences were observed in the vessel density of the DCP, except for the parafoveal (P = 0.037) and the parafoveal temporal (P = 0.048) sectors. The choriocapillaris flow area and the flow density were significantly lower in the patients with AOFVD than in the healthy controls (P = 0.001 for both). The mean FAZ area and the retinal thickness measurements were comparable in both groups.

CONCLUSIONS

Patients with AOFVD show vascular abnormalities that can be detected with OCT-A. OCT-A, as a noninvasive imaging modality, could provide a new perspective for understanding the pathophysiology of AOFVD and could also be useful in the follow-up of these patients and in the management of the disease progression.

Evaluation of the different thresholding strategies for quantifying choriocapillaris using optical coherence tomography angiography

BACKGROUND

In this paper, we evaluate the different thresholding strategies that have been used for the quantification of the choriocapillaris (CC) and explore their repeatability and the interchangeability of the measurements resulting from its application.

METHODS

Observational study. Eighteen eyes from nine healthy volunteers aged >18 years were imaged four consecutive times with a SD-OCTA system (Heidelberg Engineering, Germany) using a 10°×10° high-resolution protocol centered on the fovea. Projection artifacts were removed, and the CC was bracketed between 10 and 30 µm below Bruch's membrane. For the quantification of CC, we used four flow deficits (FD) parameters: FD number, mean FD size, total FD area and FD density. We performed a systematic review of literature to collect the thresholding methods that have been used for the quantification of CC. The CC quantification parameters were then evaluated after applying each of the thresholding strategies. Intraclass correlation coefficient (ICC) and Pearson's correlation analysis were used to compare the repeatability and interchangeability among the different thresholding strategies for quantifying the CC.

RESULTS

A total of 72 optical coherence tomography angiography (OCTA) examinations were considered. The systematic review allowed us to conclude that three local thresholding strategies (Phansalkar, mean and Niblack) and three global thresholding strategies (mean, default, Otsu) have been used for CC quantification. These strategies were evaluated in our observational study. We found a high agreement within the same method in the quantification of FD number, mean FD size, total FD area and FD density but a poor agreement with different strategies. Local strategies achieved a significantly superior ICC than global ones in CC quantification.

CONCLUSIONS

In conclusion, the interchangeability of the CC quantification using different thresholding strategies is low, and direct comparisons should not be performed. Local thresholding strategies are significantly superior to global ones for quantifying CC and should be preferred. There is an unmet need for a uniform strategy to quantify CC in future studies.

VASCULAR ALTERATIONS REVEALED WITH OPTICAL COHERENCE TOMOGRAPHY ANGIOGRAPHY IN PATIENTS WITH CHOROIDEREMIA

PURPOSE

Choroideremia is a rare degenerative retinal disease that causes incurable blindness. It occurs as a result of the deficiency of the X-linked CHM gene, which encodes the Rab escort protein 1 (REP1). Gene therapy has been developed to treat CHM using adeno-associated viral vectors and is currently undergoing clinical trials. Expression of the CHM gene is ubiquitous throughout the retina, and it is therefore important to identify which retinal layers are affected in the disease process. The purpose of this study was to assess in particular the choriocapillaris using optical coherence tomography angiography because this layer is difficult to see with conventional imaging techniques.

METHODS

Six men with choroideremia were identified and underwent standardized optical coherence tomography angiography as part of an ethics-approved clinical study and were compared with age-matched control subjects.

RESULTS

The choriocapillaris appeared normal in regions where the retinal pigment epithelium remained intact, but it was deficient elsewhere. The outer retinal vasculature showed significant changes peripherally but also some changes centrally. The inner retinal vasculature appeared unaffected by the disease process.

CONCLUSION

Choroideremia is a disease in which the choriocapillaris maintains a normal structure until the loss of the overlying retinal pigment epithelium. The inner retina also appears not to be affected at the vascular level. Although this study is limited by the small number of patients eligible for inclusion in the study, the observations support the concept of targeting gene therapy to the retinal pigment epithelium and outer retina because there is no evidence of independent degeneration of the choriocapillaris.

CAPILLARY NETWORK ALTERATIONS IN X-LINKED RETINOSCHISIS IMAGED ON OPTICAL COHERENCE TOMOGRAPHY ANGIOGRAPHY

PURPOSE

To assess foveal and parafoveal vasculature at the superficial capillary plexus, deep capillary plexus, and choriocapillaris of patients with X-linked retinoschisis by means of optical coherence tomography angiography.

METHODS

Six patients with X-linked retinoschisis (12 eyes) and seven healthy controls (14 eyes) were recruited and underwent complete ophthalmologic examination, including best-corrected visual acuity, dilated fundoscopy, and 3 × 3-mm optical coherence tomography angiography macular scans (DRI OCT Triton; Topcon Corp). After segmentation and quality review, optical coherence tomography angiography slabs were imported into ImageJ 1.50 (NIH; Bethesda) and digitally binarized. Quantification of vessel density was performed after foveal avascular zone area measurement and exclusion. Patients were additionally divided into "responders" and "nonresponders" to dorzolamide therapy.

RESULTS

Foveal avascular zone area resulted markedly enlarged at the deep capillary plexus (P < 0.001), particularly in nonresponders. Moreover, patients disclosed a significant deep capillary plexus rarefaction, when compared with controls (P: 0.04); however, a subanalysis revealed that this damage was limited to the fovea (P: 0.006). Finally, the enlargement of foveal avascular zone area positively correlated with a decline in best-corrected visual acuity (P: 0.01).

CONCLUSION

Prominent foveal vascular impairment is detectable in the deep capillary plexus of patients with X-linked retinoschisis. Our results correlate with functional outcomes, suggesting a possible vascular role in X-linked retinoschisis clinical manifestations.

Reduced vessel density in deep capillary plexus correlates with retinal layer thickness in choroideremia

Background

To assess retinal layer thickness in choroideremia (CHM) and to reveal its correlation with optical coherence tomography (OCT) angiography (OCTA) findings.

Methods

The study was designed as an observational, cross-sectional clinical series of patients with CHM, which included 14 CHM eyes and 14 age-matched controls. Multimodal imaging included OCT and OCTA. The vessel density (VD) of superficial capillary (SCP), deep capillary (DCP) and choriocapillaris (CC) plexuses was analysed by OCTA. The apparently preserved retinal islet and atrophic regions were investigated separately. Main outcome measures were as follows: best-corrected visual acuity (BCVA), total retinal layers, ganglion cell layer (GCL), inner plexiform layer (IPL), inner nuclear layer (INL), outer plexiform layer (OPL), outer nuclear layer (ONL), ellipsoid zone–retinal pigment epithelium (EZ-RPE) layer, choroidal thickness and VDs of SCP, DCP and of CC.

Results

Mean BCVA was 0.0±0.0 LogMAR in both groups. GCL, ONL, EZ-RPE and choroid were significantly thinned in CHM, particularly in the atrophic region. OPL was unaffected in the apparently preserved islet, whereas INL and IPL were similarly thinned in the atrophic and apparently preserved retina. DCP appeared severely affected in both regions, while CC was only altered in the atrophic retina. Significant correlations were found between OCT and OCTA parameters.

Conclusions

Our study showed severe alterations in both outer and inner retinal layers of patients with CHM. The extended retinal involvement might be the consequence of neuronal and vascular trophic factor reduction produced by the primarily altered RPE and/or secondary Müller glial cell reaction.

Optical Coherence Tomography Angiography (OCT-A) in Choroideremia (CHM) carriers

Purposes: To explore OCT-A abnormalities in CHM carriersMethods: CHM carriers and age-matched controls were consecutively enrolled at the Eye Clinic in Florence. All patients underwent a complete ophthalmic examination, fundus photography, fundus autofluorescence (FAF) and OCT examinations. OCT-A images of the superficial capillary plexus (SCP), deep capillary plexus (DCP) and choriocapillaris slab (CC) were acquired and analyzed using ImageJ software to detect and quantify vascular density.Results: Six patients (12 eyes) and 8 age-matched controls (16 eyes) were included in our study. The mean age was 45.5 ± 16.3 years (range 15-61) for the CHM carriers and 46.6 ± 12.2 (range 18-54) for controls. All CHM carriers showed fundus abnormalities. The detected mean central retinal thickness (CRT) (220 ± 18.34 vs 227 ± 15.46; p = .342) and choroidal central thickness (CCT) (271 ± 54.28 vs 275 ± 38.36; p = .760) did not differ between the carrier and the control group, respectively. Quantitative analysis of the inner retinal vasculature disclosed no significant difference of both SCP (p = .437) and DCP (p = .859) vessel density compared to the control group. Of note, a mild reduction on the vascular flow of the CC could be detected in the carrier group compared to the control group (78.896 ± 13.972 vs 80.008 ± 10.862; p = .045).Conclusions: OCT-A allows us to underline the role of the retinal pigment epithelium in the CHM pathophysiology. Central inner retinal and choriocapillaris vascularization were preserved although the RPE was always involved in the CHM carrier: this could support a secondary role of vascular impairment in the natural history of the disease.

Study of vessel density in adult-onset foveomacular vitelliform dystrophy with optical coherence tomography angiography

BACKGROUND

To evaluate retinal and choriocapillaris (CC) vessel density in macular region in patients affected by adult-onset foveomacular vitelliform dystrophy (AOFVD) using optical coherence tomography angiography (OCTA) METHODS: A total forty-four right eyes of 44 AOFVD patients (20 females, 24 males, mean age 69.17 ± 11.57 years) divided in 3 stages (vitelliform, pseudohypopyon and vitelliruptive) and 60 normal right eyes of 60 controls (20 females, 40 males, mean age 66.04 ± 6.40 years) were included in this prospective study. We evaluated the vessel density of superficial capillary plexus (SCP), deep capillary plexus (DCP) and CC in different macular areas (whole image, parafovea and fovea). We also analyzed the subfoveal choroidal thickness (SFCT) with Enhanced Depth Image (EDI)-OCT.

RESULTS

The vessel density of SCP and of DCP did not differ between patients and controls in all macular sectors. The vessel density of CC was lower in patients compared to controls but the difference turned out to be statistically significant only in foveal region (p < 0.001). We found that the foveal vessel density of the CC was lower in vitelliform stage and significantly increased in vitelliruptive stage (p = 0.031). At EDI-OCT, the SFCT revealed a statistically significant increase in patients compared to controls (p = 0.002) whereas it was similar in the different stages of this dystrophy (p = 0.276).

CONCLUSIONS

In vitelliform stage of AOFVD, OCTA and EDI-OCT can be useful to avoid mistakes of evaluation, due to the masking effect artifact. OCTA provides us a better understanding of the vascular role in the physiopathology of the macular diseases.

Analysis of peripapillary vessel density and Bruch's membrane opening-based neuroretinal rim parameters in glaucoma using OCT and OCT-angiography

PURPOSE

To compare peripapillary vessel density (VD) measured by spectral domain optical coherence tomography angiography (SD-OCT-A) with morphometric parameters assessing the neuroretinal rim based on Bruch's membrane opening (BMO) by spectral domain optical coherence tomography (SD-OCT) in glaucoma.

METHODS

In this non-interventional cohort study, 50 eyes of 25 consecutively enrolled patients with diagnosis of glaucoma underwent SD-OCT and SD-OCT-A imaging of the optic nerve head (ONH). BMO minimum rim width (BMO-MRW) and area (BMO-MRA) as well as peripapillary retinal nerve fiber layer (RNFL) thickness were compared to peripapillary VD in the RNFL layer around the ONH.

RESULTS

Mean BMO-MRW was 221.46 ± 81.5 µm, mean BMO-MRA was 1.05 ± 0.04 mm², mean RNFL thickness was 72.46 ± 23.16 µm, and mean VD was 43.8 ± 11.4%. VD was significantly lower when morphometric parameters had lower thickness values (p < 0.01). Correlation coefficients and their 95%- confidence intervals (95%-CI) with VD were r = 0.53 (95%-CI: 0.21-0.77) for BMO-MRW, r = 0.55 (95%-CI: 0.21-0.77) for BMO-MRA, and r = 0.57 (95%-CI: 0.13-0.73) for RNFL thickness. Intra-individual VD in both eyes correlated with r = 0.72 (p < 0.001), mean VD was comparable (p = 0.6). Eyes with high global RNFL thickness (>90 µm) showed less VD variance (σ² = 48.1) compared to eyes with highly reduced RNFL thickness (<65 µm; σ² = 82.0). Best corrected visual acuity, perimetric mean defect, and PSD correlated significantly with VD (95%-CI: -0.66 to -0.10, 0.16 to 0.6, and -0.65 to -0.02, respectively).

CONCLUSIONS

Peripapillary vessel density measured by SD-OCT angiography correlates significantly with Bruch's membrane opening-based parameters measured by SD-OCT in glaucoma patients.

Comparison of methods to quantify macular and peripapillary vessel density in optical coherence tomography angiography

Purpose

To compare macular and peripapillary vessel density values calculated on optical coherence tomography angiography (OCT-A) images with different algorithms, elaborate conversion formula, and compare the ability to discriminate healthy from affected eyes.

Methods

Cross-sectional study of healthy subjects, patients with diabetic retinopathy, and glaucoma patients (44 eyes in each group). Vessel density in the macular superficial capillary plexus (SCP), deep capillary plexus (DCP), and the peripapillary radial capillary plexus (RCP) were calculated with seven previously published algorithms. Systemic differences, diagnostic properties, reliability, and agreement of the methods were investigated.

Results

Healthy eyes exhibited higher vessel density values in all plexuses compared to diseased eyes regardless of the algorithm used (p<0.01). The estimated vessel densities were significantly different at all the plexuses (p<0.0001) as a function of method used. Inter-method reliability and agreement was mostly poor to moderate. A conversion formula was available for every method, except for the conversion between multilevel and fixed at the DCP. Substantial systemic, non-constant biases were evident between many algorithms. No algorithm outperformed the others for discrimination of patients from healthy subjects in all the retinal plexuses, but the best performing algorithm varied with the selected plexus.

Conclusions

Absolute vessel density values calculated with different algorithms are not directly interchangeable. Differences between healthy and affected eyes could be appreciated with all methods with different discriminatory abilities as a function of the plexus analyzed. Longitudinal monitoring of vessel density should be performed with the same algorithm. Studies adopting vessel density as an outcome measure should not rely on external normative databases.

Retinal Vascular Impairment in Best Vitelliform Macular Dystrophy Assessed by Means of Optical Coherence Tomography Angiography

PURPOSE

To evaluate vascular abnormalities at superficial (SCP) and deep (DCP) capillary plexuses and choriocapillaris (CC) in patients with Best vitelliform macular dystrophy (BVMD) by means of optical coherence tomography angiography (OCT-A).

DESIGN

Cross-sectional case series.

METHODS

Sixty-six eyes of 33 patients with BVMD (16 male) and 33 controls were consecutively enrolled. Patients were subdivided into classic stages and underwent best-corrected visual acuity (BCVA), fundus autofluorescence and spectral domain-optical coherence tomography, and 4.5 × 4.5-mm swept-source OCT-A. Choroidal neovascularization (CNV) and capillary dilations were qualitatively assessed by 2 masked ophthalmologists. Each OCT-A slab was imported into ImageJ 1.50 and digitally binarized for quantitative analyses. Foveal avascular zone (FAZ) area was measured manually; vessel density was then quantified after the exclusion of the FAZ pixels. Eyes classified as stages 3 and 4 were evaluated together.

RESULTS

Nineteen eyes (28.8%) revealed capillary dilations at DCP, 15 of which were in stages 1 and 2. Interestingly, CNV was detected in 24 eyes (36.4%). Quantitative analysis disclosed that stages 3-4 and 5 carry significant impairment at both SCP (P < .0001 and P = .02, respectively) and DCP (P < .0001 and P = .0004, respectively) compared to controls. FAZ area was enlarged at the DCP (P = .001). Only DCP vessel density significantly correlated with the stage and BCVA.

CONCLUSIONS

Patients with BVMD show significant vascular impairment at both superficial and deep retinal plexuses, correlating with functional outcomes. These findings, especially at DCP, may improve our understanding about the pathogenesis, and may help in predicting BVMD treatment efficacy.

Foveal Avascular Zone in Normal Tension Glaucoma Measured by Optical Coherence Tomography Angiography

Aim

To measure diameter of foveal avascular zone (FAZ), FAZ area, and vessel density using Optical Coherence Tomography Angiography (OCT-A) in patients with normal tension glaucoma (NTG) and to establish the possible role of OCT-A in diagnosis and follow-up of patients with NTG.

Methods

Twenty-one eyes of 21 patients with NTG and 30 eyes of 30 healthy subjects underwent complete ophthalmic examination as well as OCT-A on ZEISS AngioPlex. 3 × 3 macula scans were used to measure vertical, horizontal, and maximum diameter of FAZ by two graders. Mean values and interobserver variability were analyzed. Image J was used for analysis of FAZ area and vessel density.

Results

Mean vertical diameter (t = 5.58, p < 0.001), horizontal diameter (t = 3.59, p < 0.001), maximum diameter (t = 5.94, p < 0.001), and FAZ area (t = 5.76, p < 0.001) were statistically significantly enlarged in the NTG group compared to those in the control group. Vessel density (t = -5.80, p < 0.001) was statistically significantly decreased in the NTG group compared to that in the control group.

Conclusion

OCT-A could have an important role in the future in diagnosis of patients with NTG. In patients with NTG, there is larger FAZ area, while the vessel density is reduced in comparison to the control group.

Quantitative changes in flow density in patients with adult-onset foveomacular vitelliform dystrophy: an OCT angiography study

PURPOSE

To quantitatively compare the flow density, the retinal thickness, and the area of the foveal avascular zone (FAZ) between patients with adult-onset foveomacular vitelliform dystrophy (AOFVD) and a healthy controls.

METHODS

Thirteen eyes (eight patients) with AOFVD and 13 matched eyes (13 patients) without any ocular pathology were included in this study. A 6 × 6 mm optical coherence tomography angiography (OCTA) scan was performed for every included eye. The flow density (superficial retinal vascular layer, deep retinal vascular layer and choriocapillary layer), retinal thickness and FAZ (superficial retinal vascular layer and deep retinal vascular layer) were subsequently analyzed.

RESULTS

The mean flow density was decreased in the AOFVD patients in all measured vascular layers. The difference from the control group was statistically significant in the parafoveal sector of the deep retinal vascular layer (P = 0.02), and a clear trend was found in the superficial retinal vascular layer (P = 0.05). Both groups had comparable FAZs in the superficial and deep retinal vascular layers. The retinal thickness values were higher in the fovea (P = 0.840) and lower in the parafoveal sectors (P = 0.125). The difference was significant in the superior parafoveal sector (P = 0.034).

CONCLUSIONS

Flow densities as measured by OCTA are decreased in the superficial retinal vascular layer and the deep retinal vascular layer in patients with AOFVD. These findings could be helpful for diagnosing and understanding the pathogenesis of this disease.