Topographic Variations of Choroidal Thickness in Healthy Eyes on Swept-Source Optical Coherence Tomography

Sex differences in choroidal vessels using novel wide-field choroidal en-face images from optical coherence tomography

This study aims to develop a method to quantify choroidal vessels in normal eyes using wide-field optical coherence tomography (OCT) en-face images. The study included participants with normal eyes in whom wide-angle OCT images were acquired to generate planarized choroidal en-face and thickness map images. The images were segmented into central, midperipheral, and peripheral areas, and the midperipheral and peripheral areas were further segmented into supratemporal, infratemporal, supranasal, and infranasal sectors. The mean planarized choroidal-vessel density (p-CVD), planarized choroidal-vessel size (p-CVS), and choroidal thickness (CT) were calculated in each sector. Sex differences were analyzed using the Mann-Whitney U test. The study included 162 participants comprising 84 female (mean age, 43.5 years; axial length, 24.0 mm) and 78 male (mean age, 44.4 years; axial length, 24.2 mm) participants with no significant differences in demographics (P ≥ 0.107). Men had a higher mean p-CVD in all regions (P < 0.001). The mean p-CVS was greater in men in all regions except for the supratemporal sector (P < 0.001). No significant differences in sex in the mean CT were observed in all regions (P ≥ 0.106). The p-CVD and p-CVS in normal eyes differ between sexes. This finding may contribute to the understanding of the pathophysiology of choroidal diseases.

Coefficient of spatial variance of choroidal thickness on swept-source optical coherence tomography in healthy eyes

PURPOSE

This study aims to introduce the coefficient of spatial variance of choroidal thickness to describe the choroidal variation and investigate its associated factors in healthy eyes.

METHODS

This retrospective cross-sectional study included 1031 eyes from 1031 subjects who received a swept-source optical coherence tomography examination. The mean choroidal thickness in the macular 6 × 6 mm region and 900 subregions of 0.2 × 0.2 mm were computed using the embedded algorithm. Before analysis, potential segmentation and magnification errors were corrected. The coefficient of spatial variance was defined as the standard deviation divided by the mean (multiplied by 100%) of the choroidal thicknesses across 900 grids. Potential factors associated with the coefficient of spatial variance were assessed using multiple linear regression.

RESULTS

The mean choroidal thickness of the entire 6 × 6 mm macular region was 204.50 ± 72.88 μm. The mean coefficient of spatial variance was 26.58 ± 8.24%, ranging from 11.00 to 61.58%. Statistical analysis revealed that the means choroidal thickness (β = - 0.08, R2 = 0.42, p < 0.001) and anterior chamber depth (β = - 2.39, R2 = 0.05, p = 0.06) were associated with the coefficient of spatial variance.

CONCLUSION

Our study first incorporated the coefficient of spatial variance to represent the spatial variation of the choroidal thickness and observed that the greater thinning of the choroid is correlated with a more pronounced spatial variation.

Choroidal and Retinal Thicknesses in Healthy Eyes Measured with Ultra-Wide-Field Optical Coherence Tomography

Ultra-wide-field optical coherence tomography (UWF-OCT) has been recently introduced into clinical ophthalmological practice. To date, there are few data on the reference values of the retinal thickness (RT) and choroidal thickness (CT) measured with this technique. This study aimed to analyze the variance in RT and CT in the healthy eyes of white Caucasian patients with UWF-OCT tests performed with the largest available scan size of 23 × 20 mm. The data were analyzed with reference to the patients' age and gender and the axial length of the eyeball. The results of UWF-OCT scanning enabled us to visualize the shape of the retina and choroid in a large portion of the eyeball. Both anatomical entities became significantly thinner at the periphery. The peripheral CT was greater in the upper and temporal sectors; the RT was higher in the nasal compared to the temporal sectors. Both the choroid and retina showed a reduced thickness with age; however, the CT and RT did not show a statistically significant correlation with the axial length after adjusting for age and gender. Age-related variations in thickness were especially prominent in the choroid. The CT in UWF-OCT testing was significantly greater in females, while the RT was greater in males. UWF-OCT testing provides additional information on the anatomical structure of the retina and choroid compared to standard-field OCT.

Inter-Individual Topographic Variation of Choroidal Thickness in Healthy Eyes on Swept-Source Optical Coherence Tomography

Purpose

To investigate the topographic characters of inter-individual variations of the macular choroidal thickness (CT).

Methods

This was a retrospective study. Macular CT data for 900 0.2 × 0.2-mm grids from 410 healthy eyes were collected from swept-source optical coherence tomography. Following the analysis of factors associated with mean CT, the β-coefficients of the included associated factors in each grid were summarized for choroidal thickness changes analysis. Additionally, the coefficient of variance (CoV), coefficient of determination (CoD), and coefficient of variance unexplained (CoVU) for CT were calculated in each individual grid to investigate the inter-individual choroidal variations pattern.

Results

Sex (β = -17.26, female vs. male), age (β = -1.61, per 1 year), and axial length (β = -18.62, per 1 mm) were associated with mean macular CT. Females had a thinner choroid in all 900 grids (0.5-26.9 µm). As age increased, the CT noticeably decreased (8.74-19.87 µm per 10 years) in the temporal regions. With axial length elongation, the thinning (7.94-24.91 µm per 1 mm) was more evident in subfoveal and nasal regions. Both the CoV (34.69%-58.00%) and CoVU (23.05%-40.78%) were lower in the temporal regions, whereas the CoD (18.41%-39.66%) was higher in the temporal regions.

Conclusions

Choroidal thinning is more predominant in the subfoveal and nasal regions with axial length elongation, but in the temporal region with aging. The inter-individual variation of CT is higher and less determined by sex, age, or axial length in the nasal regions.

Translational Relevance

Topographic variation should be considered when interpreting choroidal thickness.

Subfoveal and Parafoveal Choroidal Thickening in Patients with Keratoconus Using the ETDRS Grid on Swept-Source OCT

INTRODUCTION

There is growing evidence that confirms morphological changes in the posterior structures in patients with keratoconus (KC); however, isolated alterations could have been missed. This study assesses choroidal thickness (CT) in the fovea and beyond in KC eyes.

METHODS

This prospective case-control and non-randomized study enrolled 107 eyes, 62 eyes of 62 patients with KC, and 45 age-matched eyes of 45 control subjects with axial length in the range of 22-26 mm. Swept-source optical coherence tomography (SS-OCT) was performed to manually measure the subfoveal choroidal thickness (SCT) using a single-line scan. CT was obtained automatically from the Early Treatment Diabetic Retinopathy Study (ETDRS) grid using the 12-lines radial scan pattern. A two-way repeated-measures analysis of variance (ANOVA) was conducted to evaluate CT variations among macular eccentricity, parafoveal area, and the interaction between both factors. CT was compared in all parafoveal areas between groups and subgroups of KC.

RESULTS

SCT was significantly thicker in KC eyes (357 ± 57 µm) than in healthy eyes (325 ± 63 µm) (p < 0.001). Significant choroidal thickening was observed in the central ring and outer and inner rings of the temporal, superior, and inferior parafoveal macular areas (p < 0.001), except in the outer ring of the nasal macular zone (p > 0.05) of KC compared to healthy eyes. The CT significantly decreased from the center to the outer ring regardless of the presence of KC (p < 0.001). The choroid in the nasal macular zone was significantly thinner than that in the temporal, superior, and inferior parafoveal areas (p < 0.001).

CONCLUSIONS

The choroidal structure increased its thickness not only in the subfoveal area, but also in eight parafoveal areas of the ETDRS grid encompassing a wider area of macular examination. These findings demonstrate and corroborate that keratoconus is not a purely corneal disease. Furthermore, it confirms the role that the choroidal structure has in the pathophysiology of keratoconus.

Evaluation of Tropicamide-Phenylephrine Mydriatic Eye Drop Instillation on Choroidal Thickness

The purpose of this study is to evaluate choroidal thickness (ChT) at the subfoveal and peripheral level after the instillation of 0.5% tropicamide + 10% phenylephrine 9 hydrochloride eye drops by using OCT scans in enhanced depth image (EDI) mode. In total, 53 patients (30 males and 23 females) were involved, and the mean age was 25.62 ± 2.41 (age range: 23-36). The dominant eye was treated with tropicamide + phenylephrine (Visumidriatic Fenil 100 mg/mL + 5 mg/mL, Visufarma) while the nondominant eye was used as the control. An OCT analysis was performed on both eyes before and 30 min after the instillation of a drop of mydriatic in the dominant eye. The ChT was measured by using the OCT software measurement tool (Spectralis; Heidelberg Engineering; Heidelberg, Germany, version 6.0). The results showed a statistically significant ChT decrease (p = 0.009) in the temporal sector after the treatment with tropicamide + phenylephrine. In the subfoveal and nasal sectors, no statistically significant ChT changes were detected (p = 0.94; p = 0.85) following the administration of the mydriatic eye drops. The ChT thinning in the temporal sector following the instillation of the tropicamide + phenylephrine eye drops suggests that in the case of ChT studies, mydriatic administration should be avoided.

Pattern of choroidal thickness in early-onset high myopia

Purpose

To explore the etiology and choroidal thickness (ChT) pattern in children with early-onset high myopia (eoHM).

Methods

Sixty children with eoHM and 20 healthy controls were enrolled in this study between January 2019 and December 2021. All children underwent comprehensive ophthalmologic examinations including swept-source optical coherence tomography. ChT was measured in the subfoveal region and at 1000 μm and 2,500 μm nasal, temporal, superior, and inferior to the fovea.

Results

Overall, 120 eyes of 60 children with eoHM were examined (mean spherical equivalent, -8.88 ± 3.05 D; mean axial length, 26.07 ± 1.59 mm). Simple high myopia (SHM), familial exudative vitreoretinopathy (FEVR), and Stickler syndrome (STL) were the most frequent etiologies of eoHM and were included in further ChT analysis. Adjusted the effect of SE, multivariate regression analysis showed that children with SHM had thinnest ChT at N2500 and I2500 among the subgroups (p = 0.039, p = 0.013). FEVR group showed thinner ChT at T2500 (p = 0.023), while STL patients exhibited thin ChT at all locations.

Conclusion

This study revealed that SHM, STL and FEVR was the most frequent etiology, and showed a distinctive pattern of ChT. Asymmetric nasal ChT thinning is a distinctive biomarker for SHM, asymmetric temporal ChT thinning might serve as a biomarker for FEVR, and symmetric diffuse thinning is more common in STL. These ChT patterns may provide a convenient, fast, and noninvasive strategy to differentiate the potential etiology of eoHM.

New findings on choroidal features in healthy people by ultra-widefield swept-source optical coherence tomography angiography

To evaluate the distribution of choroidal thickness (CT) and its trend with age in healthy people using 120° ultra-wide field swept-source optical coherence tomography angiography (UWF SS-OCTA). In this cross-sectional observational study, healthy volunteers underwent single imaging of the fundus with UWF SS-OCTA at a field of view (FOV) of 120° (24 mm × 20 mm) centered on the macula. The characteristics of CT distribution in different regions and its changes with age were analyzed. A total of 128 volunteers with a mean age of 34.9 ± 20.1 years and 210 eyes were enrolled in the study. The thickest mean choroid thickness (MCT) was located at the macular region and supratemporal region, followed by the nasal side of the optic disc, and thinnest below the optic disc. The maximum MCT was: 213.40 ± 36.65 μm for the group aged 20-29, and the minimum MCT was: 162.11 ± 31.96 μm for the group aged ≥ 60. After the age of 50, MCT was significantly and negatively correlated decreased with age (r = - 0.358, p = 0.002), and the MCT in the macular region decreased more remarkably compared to other regions. The 120° UWF SS-OCTA can observe the distribution of choroidal thickness in the range of 24 mm × 20 mm and its variation with age. It was revealed that MCT decreased more rapidly in the macular region relative to other regions after 50 years old.

Advances in swept-source optical coherence tomography and optical coherence tomography angiography

Background

The fast development of swept-source optical coherence tomography (SS-OCT) and swept-source optical coherence tomography angiography (SS-OCTA) enables both anterior and posterior imaging of the eye. These techniques have evolved from a research tool to an essential clinical imaging modality.

Main text

The longer wavelength and faster speed of SS-OCT and SS-OCTA facilitate better visualization of structure and vasculature below pigmented tissue with a larger field of view of the posterior segment and 360-degree visualization of the anterior segment. In the past 10 years, algorithms dealing with OCT and OCTA data also vastly improved the image quality and enabled the automated quantification of OCT- and OCTA-derived metrics. This technology has enriched our current understanding of healthy and diseased eyes. Even though the high cost of the systems currently limited the widespread use of SS-OCT and SS-OCTA at the first beginning, the gap between research and clinic practice got obviously shortened in the past few years.

Conclusions

SS-OCT and SS-OCTA will continue to evolve rapidly, contributing to a paradigm shift toward more widespread adoption of new imaging technology in clinical practice.

NORMAL PERIPHERAL CHOROIDAL THICKNESS MEASURED BY WIDEFIELD OPTICAL COHERENCE TOMOGRAPHY

PURPOSE

Choroidal stasis plays an important role in the pathogenesis of many conditions and leads to choroidal thickening. However, the normal peripheral choroidal thickness (PCT) pattern remains unknown. This study investigated PCT and associated factors using ultrawidefield optical coherence tomography in healthy eyes.

METHODS

This cross-sectional study included 120 healthy eyes (57 males; age, 52.0 ± 20.5 years). We used choroidal thickness maps created by ultrawidefield optical coherence tomography (viewing angle, 200°) with real-shape correction. The peripheral area was defined from 60° to 100° and further separated vertically and horizontally. The PCT and the correlations between PCT and subjects' characteristics were examined.

RESULTS

The PCT were 227.1 ± 57.0 µ m, 199.6 ± 53.9 µ m, 196.6 ± 57.1 µ m, and 148.0 ± 38.2 µ m in supratemporal, infratemporal, supranasal, and infranasal areas, respectively. The thickest peripheral sector was most frequently observed in supratemporal (69.2%). The PCT negatively correlated with age in all regions ( P -values < 0.001) and axial length in supratemporal, supranasal, and infranasal areas ( P -values ≤ 0.003). The temporal PCT was thicker on the side contiguous with the posterior pole Haller's vessels ( P -values ≤ 0.020).

CONCLUSION

The PCT is associated with age, axial length, and the running pattern of Haller's vessels.

Choroidal morphologic features in central serous chorioretinopathy using ultra-widefield optical coherence tomography

PURPOSE

To analyze the choroidal morphological changes in central serous chorioretinopathy (CSC) using ultra-widefield (UWF)-optical coherence tomography (OCT).

METHODS

This single-center, case-control study included 65 CSC eyes (52 males; age, 55.6 ± 13.0 years) and 65 healthy eyes (50 males; age, 57.1 ± 17.9 years). UWF-OCT (viewing angle, 200°) with real-shape correction was used to create an automated choroidal thickness (CT) map. The CT map had three sub-areas: the central (0-30°), middle (30-60°), and peripheral areas (60-100°), and was divided by vertical and horizontal lines. Differences in the CT and the CT change rate (CTCR) from the central to peripheral areas were examined between the CSC and control groups after adjusting for subjects' demographic and clinical factors. Furthermore, we assessed the vortex veins dilation patterns (VVDP) in the macula and examined the CT and the CTCR differences between CSC patients and controls for each VVDP.

RESULTS

CSC patients had greater CT than those of the controls in all sectors (CSC vs. controls, the peripheral area: supratemporal 284.4 ± 71.2 μm vs. 220.4 ± 71.2 μm, infratemporal 263.3 ± 69.2 μm vs. 195.3 ± 52.3 μm, supranasal 251.9 ± 70.3 μm vs. 189.5 ± 58.1 μm, infranasal 193.6 ± 71.2 μm vs. 146.3 ± 48.9 μm, P < 0.0001 for all sectors). The CTCR was apparently larger in CSC eyes than controls only for the upper-dominant type of VVDP (CSC patients vs. controls, supratemporal 32.1 ± 9.9% vs. 4.6 ± 23.1%, infratemporal 44.0 ± 11.2% vs. 25.6 ± 16.8%, supranasal 42.6 ± 9.8% vs. 22.2 ± 19.4%, infranasal 57.6 ± 41.2% vs. 41.2 ± 13.9%, P < 0.0001 for all sectors).

CONCLUSIONS

CSC has a thicker choroid, even in the peripheral areas, and the macular choroidal thickening was more severe in the upper-dominant type of VVDP. VVDP may affect the location of excessive fluid.

Morphometrics in three dimensional choroidal vessel models constructed from swept-source optical coherence tomography images

We created three types of vessel models: vessel volume, surface, and line models from swept-source optical coherence tomography images and tested experimentally calculated three-dimensional (3D) biomarkers. The choroidal volume (CVolume), surface area (VSurface), and vessel length-associated index (VLI) were measured. The calculated 3D parameters were the mean choroidal thickness, choroidal vascularity index (CVI), vessel length density index (VLDI), vessel length to the stromal (VL–S) ratio, surface-to-volume ratio (S–V ratio), and vessel diameter index (VDI). Cluster analysis showed that the parameters were classified into two clusters: one was represented by the VVolume including the CVolume, VSurface, CVI, S–V ratio, VLI, VDI, and subfoveal choroidal thickness and the other by the VL–S ratio including the VLDI. Regarding the regional distribution, the VVolume, CVolume, VSurface, CVI, VLI, VL–S ratio, and VDI at the foveal center were higher than at the parafovea (P < 0.01). Although the VVolume decreased with age and axial length (AL) elongation, the association of the 3D parameters with age and AL elongation differed. The VLI, VLDI, VL–S ratio, and CVI decreased with age (P < 0.01) but not with AL elongation. The results suggested a structural difference in the choroidal vessel volume reduction between aging and AL elongation. The 3D parameters may provide additional information about the choroidal vasculature.

Two-Year Choroidal Thickness Attenuation and Its Associations in Healthy Chinese Adults

Purpose

Identifying clinical associations causing attenuation in choroidal thickness (CT) among healthy Chinese adults.

Methods

A 2-year longitudinal study was conducted in volunteers aged over 30 years from China. All participants had no history of eye disease or surgery. All subjects underwent swept-source optical coherence tomography to measure the CT in the macular region at baseline and at 2-year follow-up. The regression models were based on the generalized estimating equation.

Results

A total of 603 eyes of 336 healthy participants were included in the final analysis (mean [SD] age, 58.88 [8.82] years; 74.70% female). Mean (SD) choroidal thickness (MCT) was reduced significantly from 206.62 (72.42) to 194.02 (72.08) µm (difference, −12.60 µm; 95% confidence interval [CI], −13.62 to −11.57). Among the Early Treatment of Diabetic Retinopathy Study (ETDRS) grid, CT at the subfoveal sector showed the greatest 2-year reduction (difference, −14.55 µm; 95% CI, −15.87 to −13.22). The largest 2-year change was observed in the 50 to 59 years group (difference, −14.51 µm; 95% CI, −16.71 to −12.32). Multivariate regression showed female gender (β = −2.85; 95% CI, −5.65 to −0.56) and baseline MCT (β = −0.040; 95% CI, −0.056 to −0.024) were significantly and independently associated with greater 2-year CT decrease.

Conclusions

These results indicated that CT among Chinese healthy adults decreased during the 2-year follow-up, and the greater choroidal thinning rate was significantly associated with female gender and larger baseline MCT.

Translational Relevance

Longitudinal CT data of healthy adults provide a reference range when evaluating pathologic variations, especially for the age-related retinal-choroidal disorders.

Factors related to the location of pigment epithelial detachment in central serous chorioretinopathy

Pigment epithelial detachment (PED) is common in eyes with central serous chorioretinopathy (CSC), and choroidal neovascularisation (CNV), which is almost always associated with PED, is found in a higher proportion than previously expected. Using en-face optical coherence tomography, this retrospective study aimed to investigate the PED location in relation to various geometric landmarks including the foveal centre (FC), greatest choroidal thickness (GCT) point and optic disc centre. In a total of 98 eyes, the distance from the FC to PED centroid was correlated with the ratio of GCT to subfoveal choroidal thickness (r = 0.278, P = 0.006) and the distance from the FC to GCT point (r = 0.371, P < 0.001). Eyes with CNV had a shorter distance between the PED centroid and FC (700 ± 439 μm) than those without (1191 ± 964 μm, P = 0.001). Analysis of covariance showed that the distance from the FC to the PED centroid was significantly correlated with the distance from the FC to the GCT point (P = 0.009) and the PED group with and without CNV (P = 0.020). This result suggests that the development of complicated PED with CNV can be related to both choroidal vascular abnormalities and retinal pigment epithelial insufficiency.

Choroidal vascularity index in thyroid eye disease: comparison with controls and application in diagnosing non-inflammatory active disease

PURPOSE

To report the differences in choroidal vascularity index (CVI) in thyroid eye disease (TED) and normals and its discriminatory value for differentiating various stages of TED.

METHODS

Prospective, cross-sectional, non-interventional imaging study. Ninety-four eyes of 54 patients were included and divided into 5 groups - normal controls (C), inactive TED (I), active TED (A), non-inflammatory active TED (NIA) and systemic hyperthyroid disorder but no TED (SYS). Choroidal images were acquired using the swept-source optical coherence tomography and the choroid was binarized to calculate the CVI.

RESULTS

Ninety-four eyes were included. Mean age was 44.52 ± 10.02 years (median 46 years, range 19-65 years). Mean IOP was 16.1 ± 3.37 mm Hg (median 16 mm Hg, range 16-24 mm Hg). Mean Spherical equivalent (SE) was -0.08 ± 1.86 diopters (median 0, range -2.5 to +2.25). Intra-rater agreement was 0.84 (p < 0.001). Inter-rater agreement was noted to be 0.85 (p < 0.001) for consistency and 0.77 (p < 0.001) for absolute agreement. CVI in the A group was 70.11 ± 3.38% and in the NIA group was 69.32 ± 3.5%. Both were comparable to each other and significantly higher than the C, I and SYS groups (p < 0.001). Multiple regression showed that the Clinical Activity Score (CAS) had a positive effect and spheroequivalent had a negative effect on the CVI. At CVI of 66.83%, active TED can be diagnosed with sensitivity of 91.67% and specificity of 82.14%                 .

CONCLUSIONS

CVI is significantly higher in active TED and NIA TED compared to other groups. It has a good value in differentiating the non-inflammatory active TED eyes from the inactive eyes.

Ultra-Widefield Indocyanine Green Angiography Reveals Patterns of Choroidal Venous Insufficiency Influencing Pachychoroid Disease

Purpose

To compare patterns of choroidal venous drainage in eyes with pachychoroid disease to those of healthy subjects using ultra-widefield indocyanine green angiography (UWF ICGA).

Methods

Patients with pachychoroid disease and healthy controls were recruited at two referral centers. UWF ICGA images were used to evaluate the proportion of the postequatorial fundus drained by major vortex vein systems in each quadrant and to study the incidence and topography of choroidal vascular hyperpermeability (CVH) and intervortex venous anastomoses. Widefield swept-source optical coherence tomography (SS-OCT) was used to evaluate choroidal thickness at the posterior pole in eyes with pachychoroid disease.

Results

Fifty-two pachychoroid eyes and 26 healthy eyes were evaluated. Eyes with pachychoroid disease showed a significant within-subject variance in the proportion of the postequatorial fundus drained by each vortex vein system (range, 4.1%–48.1%; P < 0.0001) that was not seen in controls (range, 17.3%–31.7%; P = 0.11). CVH was present in all pachychoroid disease eyes and three of 26 controls. Intervortex venous anastomoses were present in 46 of 52 pachychoroid disease eyes and nine of 26 control eyes. Vortex vein systems with large drainage areas showed greater density of CVH spots. SS-OCT demonstrated asymmetric choroidal drainage in the macula of 59% of pachychoroid eyes. CVH and intervortex venous anastomoses were more prominent in areas showing maximal choroidal thickness.

Conclusions

In eyes with pachychoroid disease, imbalanced choroidal venous drainage with congestion of specific vortex vein systems may contribute to a state of choroidal venous insufficiency characterized by regional choroidal thickening, CVH and remodeling of venous drainage routes.

Choroidal Thickness in Thyroid Eye Disease: Comparison With Controls and Application in Diagnosing Non-Inflammatory Active Disease

Introduction

Choroidal thickness is known to vary in various systemic diseases. In the current study, we aim to report the differences in choroidal thickness in thyroid eye disease (TED) and normals and its discriminatory value for differentiating various stages of TED.

Methods

Prospective, cross-sectional, non-interventional imaging study. In an institutional practice, 102 eyes of 51 patients were included and divided into five groups: normal controls (C), inactive TED (I), active TED (A), non-inflammatory active TED (NIA) and systemic thyroid disorder but no TED (SYS). Choroidal images were acquired using the swept-source optical coherence tomography (Topcon DRI OCT Triton) with automatic layer segmentation which provided an automatic measurement of the subfoveal choroidal thickness and the mean in nine subfields based on the Early Treatment Diabetic Retinopathy Study (ETDRS) grid. One-way analysis of variance (ANOVA), Youden index and area under the receiver operating characteristic curves (AUROC) were reported.

Results

Central choroidal thickness in the A group was 279±37.52 microns and in the NIA group was 302.5±59.22 microns. Both were comparable to each other and significantly higher than the C, I and SYS groups (p<0.001). All ETDRS sub-fields showed significant AUROC to distinguish NIA from I. Most significant Youden index was for the inner nasal and central ETDRS subfields (0.55 and 0.61 respectively). Inner nasal sub-field showed 100% specificity while the central sub-field, showed 86.5% for predicting NIA. At a choroidal thickness of >266 microns, the central sub-field had the strongest discriminatory potential to predict NIA. 

Conclusion

Choroidal thickness is greater in active and non-inflammatory active TED. The inner nasal and central ETDRS sub-fields have value in differentiating the non-inflammatory active TED eyes from the inactive eyes.

Evaluation of Choroidal Thickness Using Optical Coherent Tomography: A Review

The choroid is the main source of blood and nourishment supply to the eye. The dysfunction of the choroid has been implicated in various retinal and choroidal diseases. The identification and in-depth understanding of pachychoroid spectrum disorders are based on the tremendous progress of optical coherence tomography (OCT) technology in recent years, although visibility of choroid is challenging in the era of the time or spectral domain OCT. The recent rapid revolution of OCTs, such as the enhanced depth imaging OCT and the swept-source OCT, has greatly contributed to the significant improvement in the analysis of the morphology and physiology of the choroid precisely, especially to the choroid-scleral boundary and vasculature. The present review highlights the recently available evidence on the measurement methodology and the clinical significance of choroidal thickness in retinal or choroidal disorders.

Choroidal thickness and vessel pattern in myopic eyes with dome-shaped macula

AIM

To analyse the choroidal thickness (CT) and vessel pattern of myopic patients with dome-shaped macula (DSM) and their association with the DSM axis and serous retinal detachment (SRD).

METHODS

Retrospective study. The CT and vessel pattern were assessed on optical coherence tomography (OCT), OCT-angiography and ultra-wide-field photography.

RESULTS

27 eyes of 18 subjects (mean age: 65 years) were included. Compared with the 11 eyes (41%) with horizontal DSM, the 16 eyes (59%) with vertical DSM had a shorter axial length (25.8±2 mm vs 28.3±2.5 mm; p=0.01), a higher mean macular bulge height (624.4±207 µm vs 255.4±160.3 µm; p=0.0001) and a thicker CT (183.1±91.1 µm vs 72±38.3 µm; p<0.001). Large choroidal vessels crossed the macular area in 75% of eyes with vertical DSM vs 27% of eyes with horizontal DSM (p=0.02), whereas a watershed zone framing the macula was more often seen in horizontal DSM (72% vs 25%, p=0.02). Thirteen eyes (48%) had an SRD that was not associated with the DSM axis, the mean bulge height, the CT or the vessel pattern.

CONCLUSION

The presence of an SRD did not correlate with the DSM axis, the CT or the vessel pattern. However, the rate of large choroidal vessels crossing the macula was higher in vertical DSM than in horizontal DSM.

CHOROIDAL VASCULARITY INDEX IN YOUNG CHOROIDEREMIA PATIENTS

PURPOSE

To evaluate choroidal features in young patients affected by choroideremia (CHM).

METHODS

Young CHM patients and control subjects were recruited at the Eye Clinic in Florence. High-resolution choroidal imaging was obtained using swept-source optical coherence tomography with long optical coherence tomography scans (12 × 9 mm optical coherence tomography scans). We considered the subfoveal choroidal area within 9 mm of the optic disk in the horizontal plane and the subfoveal choroidal area within a 3-mm diameter centered over the fovea. The subfoveal choroidal thickness, total choroidal area, luminal area, stromal area, and choroidal vascularity index were assessed using the "ImageJ" software in both groups.

RESULTS

Eight patients (16 eyes; mean age, 19.3 ± 5.2 years) and seven control subjects (14 eyes; mean age, 19.0 ± 5.0 years) were included in this study. Best-corrected visual acuity was 20/20 in both eyes of seven CHM patients and in all control subjects and 20/25 in both eyes in one CHM patient. Mean subfoveal choroidal thickness did not differ between CHM patients and control subjects. Luminal area9mm, stromal area9mm, and total choroidal area9mm were reduced in patients compared with the control group. Luminal area3mm, stromal area3mm, and total choroidal area3mm did not differ between patients and control subjects. Choroidal vascularity index9mm and choroidal vascularity index3mm were not different between patients and control subjects.

CONCLUSION

There are no differences in the choroidal vascularity index between young CHM patients and control subjects; this result suggests a simultaneous, proportional impairment of both the stromal and vascular components of the choroid in the early stages of the disease.

Comparison of Regional Differences in the Choroidal Thickness between Patients with Pachychoroid Neovasculopathy and Classic Exudative Age-related Macular Degeneration

Purpose: To compare the regional differences in the choroidal thickness (CT) between patients with pachychoroid neovasculopathy (PNV) and classic exudative age-related macular degeneration (ceAMD).Materials and Methods: We included both eyes of patients with unilateral macular neovascularization (MNV) due to ceAMD or PNV. Unilateral eyes of normal subjects were also included as a normal control group. The regional difference in CT was defined as a difference between the macular and extramacular areas, and calculated as the ratio of subfoveal CT (SFCT) to nasal peripapillary CT (PCT).Results: In normal subjects, the choroid was 2.25 ± 0.10 times thicker at the macula than at the extramacular area. The SFCT and PCT were significantly affected by age (P < .001 and P < .001, respectively), whereas the regional difference in CT were independent of age (P = .076). Analysis of covariance including age, sex, and MNV group showed that regional difference in CT were significantly affected by sex, nasal peripapillary CT, and MNV group (P = .023, P < .001, and P < .001, respectively). The estimated marginal mean of the regional difference in CT was significantly smaller in the ceAMD group (1.671 ± 0.103) than in the normal control (2.250 ± 0.095, P = .003) and PNV groups (2.0880 ± 0.086, P < .001).Conclusions: Regional differences in CT were consistent with aging. However, the difference varied with the presence of PNV or ceAMD. Measurement of regional differences in CT provides additional information for characterizing the choroid in patients with MNV.

Long term outer retinal changes in central serous chorioretinopathy submitted to half-dose photodynamic therapy

PURPOSE

To evaluate long-term changes in the foveal and parafoveal outer retina after half-dose photodynamic therapy (HD-PDT) in central serous chorioretinopathy (CSC).

METHODS

Retrospective study including CSC patients submitted to HD-PDT. Best corrected visual acuity (BCVA) was evaluated. Spectral-domain optical coherence tomography automatic segmentation algorithm was used and data on retinal, inner retinal, outer retinal and outer nuclear layers (ONL) in both foveal 1 mm (C) and parafoveal 3 mm ETDRS circles for the superior, nasal, inferior and temporal sectors, were obtained at baseline and 3, 12 and 24 months post-treatment. Subfoveal choroidal thickness, photoreceptors' outer segment thickness, subretinal fluid (SRF) height and width were also measured.

RESULTS

Twenty-one eyes of 15 patients were included. At baseline, the mean ONL thickness in the foveal area was significantly thinner in affected eyes compared to their fellow unaffected ones (55,50 ± 32,75 μm vs 93,00 ± 17,0 μm; p = 0,011), and was negatively correlated to logMAR BCVA (R=-0,601, p = 0,008) ONL thickness increased by 10,94 ± 11,88 μm at 24 months in the foveal area, and all the parafoveal sectors presented a similar increase. Baseline SRF width was significantly correlated with baseline BCVA (R1 = 0,483, p = 0,036), and with ONL thickness in all sectors.

CONCLUSION

In our study we found a significant long-term increase in foveal and parafoveal ONL thickness in CSC after HD-PDT, suggesting that this seems to be a safe treatment for the outer retina. This is the first study mapping the outer retinal changes in the macular area to 24 months follow up.

Retinal applications of swept source optical coherence tomography (OCT) and optical coherence tomography angiography (OCTA)

The advent of optical coherence tomography (OCT) revolutionized both clinical assessment and research of vitreoretinal conditions. Since then, extraordinary advances have been made in this imaging technology, including the relatively recent development of swept-source OCT (SS-OCT). SS-OCT enables a fast scan rate and utilizes a tunable swept laser, thus enabling the incorporation of longer wavelengths than conventional spectral-domain devices. These features enable imaging of larger areas with reduced motion artifact, and a better visualization of the choroidal vasculature, respectively. Building on the principles of OCT, swept-source OCT has also been applied to OCT angiography (SS-OCTA), thus enabling a non-invasive in depth-resolved imaging of the retinal and choroidal microvasculature. Despite their advantages, the widespread use of SS-OCT and SS-OCTA remains relatively limited. In this review, we summarize the technical details, advantages and limitations of SS-OCT and SS-OCTA, with a particular emphasis on their relevance for the study of retinal conditions. Additionally, we comprehensively review relevant studies performed to date to the study of retinal health and disease, and highlight current gaps in knowledge and opportunities to take advantage of swept source technology to improve our current understanding of many medical and surgical chorioretinal conditions. We anticipate that SS-OCT and SS-OCTA will continue to evolve rapidly, contributing to a paradigm shift to more widespread adoption of new imaging technology to clinical practice.