REPEATABILITY OF CHOROIDAL THICKNESS MEASUREMENTS ASSESSED WITH SWEPT-SOURCE OPTICAL COHERENCE TOMOGRAPHY IN HEALTHY AND DIABETIC INDIVIDUALS

Automated analysis of choroidal thickness in patients with systemic lupus erithematosus treated with hydroxychloroquine

PURPOSE

To evaluate the influence of hydroxychloroquine (HCQ) in choroidal thickness (CT) in patients with systemic lupus erythematous (SLE), considering the possible impact of disease activity on the choroid.

METHODS

Cross-sectional study comparing three groups: two groups of SLE patients treated with HCQ without HCQ-retinopathy (32 eyes/32 patients with < 5 years of HCQ (group 1) and 44 eyes/44 patients with > 5 years of HCQ (group 2)), and an age-matched healthy control group of 46 eyes/46 patients (group 3). A complete ophthalmic examination was performed, including swept-source optical coherence tomography (SS-OCT) Triton (Topcon). Data were correlated to systemic disease activity parameters.

RESULTS

CT was thicker in group 1 compared to group 3 in central, nasal, and superior sectors, and to group 2 in inner superior and outer inferior sectors (p < 0.05). In the correlation analysis, disease activity and CT were inversely correlated in most sectors (p < 0.05). In the regression analysis, HCQ was related to thinner CT in temporal and inferior sectors and disease activity with variations in nasal sectors (p < 0.05).

CONCLUSIONS

In SLE patients, HCQ is correlated to decreased CT, especially in the inferior and temporal areas. The choroid shows different responses to SLE activity and HCQ, and some sectors may be more sensitive than others.

Influence of inflammatory plasma biomarkers on choroidal thickness in type 2 diabetes mellitus

PURPOSE

To assess the influence of inflammatory plasma biomarkers on choroidal thickness (CT) in patients with type 2 diabetes (T2D).

METHODS

Cross-sectional study enrolling T2D patients and age-matched healthy controls (>55 years of age, Caucasian, axial length <26 mm, no macular edema, and naïve). Patients were examined with swept-source OCT Triton, obtaining automatic measurements. CT was analyzed using the ETDRS grid and the recently proposed choroidal division. A blood analysis was commanded: general biochemical profile, liver status, T2D status, thyroid and parathyroid activity, coagulation, general immunological profile, and inflammatory biomarkers.

RESULTS

124 eyes of 124 patients with a mean age between 66 and 68 years were examined. The new choroidal division showed differences between groups (p < 0.05) in more sectors than the ETDRS grid, and more biomarkers influenced these new sectors. T2D patients had higher levels of IL-8, TNF-α, MCP1, adiponectin and L-selectin. CT was influenced by TNF-α, IL-17, leukocytes and erythrocyte sedimentation rate, as well as by HDL cholesterol, albumin, liver function biomarkers, and TSH. HbA1c showed little influence on CT.

CONCLUSIONS

T2D patients present increased plasma inflammatory biomarkers, exhibiting an influence on CT. IL-17 is related to a thicker choroid but TNF-α is related to a thinner choroid. HbA1c has little influence on CT. The recently proposed choroidal division is more sensitive to CT changes than the ETDRS grid. Some sectors are more sensitive to plasma biomarkers.

Direct Estimation of Choroidal Thickness in Optical Coherence Tomography Images with Convolutional Neural Networks

Automatic and accurate estimation of choroidal thickness plays a very important role in a computer-aided system for eye diseases. One of the most common methods for automatic estimation of choroidal thickness is segmentation-based methods, in which the boundaries of the choroid are first detected from optical coherence tomography (OCT) images. The choroidal thickness is then computed based on the detected boundaries. A shortcoming in the segmentation-based methods is that the estimating precision greatly depends on the segmentation results. To avoid the dependence on the segmentation step, in this paper, we propose a direct method based on convolutional neural networks (CNNs) for estimating choroidal thickness without segmentation. Concretely, a B-scan image is first cropped into several patches. A trained CNN model is then used to estimate the choroidal thickness for each patch. The mean thickness of the choroid in the B-scan is obtained by taking the average of the choroidal thickness on each patch. Then, 150 OCT volumes are collected to evaluate the proposed method. The experiments show that the results obtained by the proposed method are very competitive with those obtained by segmentation-based methods, which indicates that direct estimation of choroidal thickness is very promising.

Effects of refractive accommodation on subfoveal choroidal thickness in silicone oil-filled eyes

Purpose

To investigate the effects of refractive accommodation on subfoveal choroidal thickness (SFCT) in silicone oil (SO)-filled eyes.

Methods

This retrospective, self-comparative study was conducted on 40 patients with unilateral macula-on rhegmatogenous retinal detachment, who underwent vitrectomy and SO tamponade. The SFCT of SO-filled eyes and the fellow control eyes were measured using optical coherence tomography at their one-month visit after surgery. The patients wore soft contact positive lenses for 24 h in the SO-filled eyes, to correct their refractive error. SFCT and choroidal vascularity index (CVI) were measured before and after wearing the contact lenses. Mean SFCT was compared between SO-filled eyes and the fellow control eyes, and SFCT and CVI were compared before and after refractive error correction in the SO-filled eyes.

Results

Mean SFCT of SO-filled eyes (221.52 ± 38.41 um) was less than that of the fellow eyes (273.41 ± 31.30 um) (P < 0.001). After refractive error correction, the mean SFCT increased to 269.28 ± 36.90 um(P < 0.001). However, CVI decreased from 57.01 ± 2.41 to 55.39 ± 2.39 (P < 0.05).

Conclusions

SFCT reduction in SO-filled eyes was primarily due to the hyperopia status. The non-uniform change in CVI suggests that changes in CT are mainly attributed to a greater expansion of the stromal area instead of the choroidal vascular area.

Trial registration

This study protocol was reviewed and approved by the Ethics Committee of the Central Theater General Hospital, approval number No. [2020]058–1, retrospectively registered.

Choroidal thickness measurements in different ethnicities using swept source optical coherence tomography: repeatability and assessment

Clinical relevance: Swept-source optical coherence tomography may not provide reliable measurements of choroidal thickness for pigmented subjects.Background: The repeatability of choroidal thickness measurements in young healthy adults was investigated using swept source optical coherence tomography.Methods: Choroidal thickness was measured using swept source optical coherence tomography in 98 healthy subjects (49 South Asian and 49 Caucasian) aged between 19 and 28 years old. Repeated radial scan images centred on the fovea were obtained from the right eye with 5 min between measurements. Choroidal thickness values were obtained from the built-in automated segmentation algorithm for the 9 subfields defined by the Early Treatment Diabetic Retinopathy Study. Interclass correlation coefficients and Bland-Altman methods were used to assess test-retest repeatability.Results: The mean ± standard deviation sub-foveal choroidal thickness was 316.53 ± 63.36 µm for the Caucasian group and 292.70 ± 60.13 µm for the South Asian group. Bland-Altman analysis showed smaller test-retest variability for choroidal thickness measurements in the Caucasian group (mean difference ± SD = -0.01 ± 6.59 µm) compared to the South Asian group (mean difference ± SD = -2.38 ± 12.20 µm). No relationship was found between the mean choroidal thickness and mean spherical equivalent of refractive error for both subject groups.Conclusion: Swept source optical coherence tomography is capable of obtaining choroidal thickness measurements with good repeatability. However, test-retest limits of agreement are substantially greater in South Asian subjects, suggesting that successful identification of the choroidal scleral interface may be affected by the amount of pigmentation present in the retinal and choroidal tissues.

Choroidal Differences between Spectral and Swept-source Domain Technologies

PURPOSE OF THE STUDY

To assess differences in healthy eyes in volume (CV) and choroidal thicknesses (CT) across all macular Early Treatment Diabetic Retinopathy Study (ETDRS) areas measured by swept source (SS)-OCT and spectral domain (SD)-OCT with enhanced depth imaging (EDI).

MATERIALS AND METHODS

One hundred and fifty healthy eyes were studied in patients aged between 21-68 years. All of these patients underwent an ophthalmic examination that included axial length (AL), a fast macula protocol with EDI by Spectralis SD-OCT, and a 3D macular cube by DRI-Triton SS-OCT. CT and CV values were measured after a manual segmentation with SD-OCT and automatically with SS-OCT.

RESULTS

The values obtained by SD-OCT were statistically higher than the values obtained by SS-OCT in all ETDRS areas. To determine the differences that were related to total CV or AL, the eyes were divided depending on their total CV and AL values into two groups. There were persistent differences between the two devices that were not related to the total CV. In subjects with a higher AL, these differences were not present in either the total CV or the subfoveal CT. In longer eyes, the differences diminished, and there were no statistical differences between the devices in the subfoveal area, temporal quadrants, inferior inner ring, or CV.

CONCLUSIONS

The choroidal values obtained with the SD-OCT are statistically higher than those measured by SS-OCT. Both techniques are able to clearly visualize the choroidoscleral interface and provide different values that are highly correlated. These differences are smaller in eyes with a longer AL and are not related to the total CV.

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

Purpose

To assess topographic variations of choroidal thickness (CT) in the fovea and beyond in healthy eyes.

Methods

This cross-sectional study included healthy subjects ≤ 55 years of age with axial lengths (22-26 mm) and refractive error margins (-4D, +4D) in normal ranges. Images were acquired using swept-source optical coherence tomography angiography (OCT-A). Corneal thickness (CT) maps from 12 × 12-mm radial scans and 9 × 9-mm OCT-A B-scans were analyzed.

Results

The study included 64 eyes of 33 subjects (mean age, 37 years). Mean CT was >300 µm in all locations except the nasal outer macula. The subfoveal CT was >395 µm in 30% of cases; in 38.7% of cases, >50% of the CT map was thicker than 395 µm. The mean thickest choroidal point was 395.2 µm (range, 164-548 µm), located superior and temporal to the macula in 72.2% of cases and subfoveally in 1.8% of cases. The CT pattern was symmetrical (58%) or asymmetrical (42%) along a horizontal axis correlating with choroidal vein distribution. Half of the asymmetrical patterns were thicker in the inferior quadrants, with an oblique temporal watershed of venous drainage, and the other half were thicker superiorly. The mean vascularity index was ∼75% regardless of the mean CT.

Conclusions

One-third of healthy eyes of patients younger than age 55 had a thick choroid (>395 µm). In these normal eyes, the thickest choroidal point was not subfoveal, CT symmetry above and below the fovea depended on choroidal vein distribution, and choroidal vascularity index was independent from CT. No patients demonstrated fundus autofluorescence abnormalities, and the choriocapillaris remained visible even in thick choroids. These features could be interesting when differentiating normal versus pathological states.

Repeatability and reproducibility of retinal and choroidal thickness measurements in Diabetic Macular Edema using Swept-source Optical Coherence Tomography

Purpose

To evaluate the repeatability and reproducibility of retinal and choroidal thickness measured with Swept source Optical Coherence Tomography (SS-OCT) in eyes with Diabetic Macular Edema (DME).

Methods

42 DME eyes were imaged using SS-OCT standard Macular scanning protocols. Retinal and choroidal thickness were measured in the Total macular circle (TMC) and foveal central subfield (FCS) using device-integrated specific software. The coefficient of repeatability (CR) and intraclass correlation coefficient (ICC) were determined as a measure of repeatability and relative reliability within graders. Reproducibility was assessed using Bland-Altman plots and 95% limits of agreement (LoA) were determined as a measure of interobserver variability.

Results

Intragrader CR of retinal and choroidal thickness were 8.37 and 12.20 microns for TMC and 22.24 and 32.40 microns for FCS, and intergrader 95% LoA were 7.37–8.69 and -27.2–27.71 microns for TMC and -34.21–41.93 and -30.46–24.84 for FCS, respectively. Retinal and choroidal thickness showed very good intraobserver reliability for both TMC and FCS (ICC 0.99, LoA 0.98–0.99 in all cases). Intraobserver and interobserver variability for retinal and choroidal thickness was not significantly different for TMC (p = 0.98 and p = 0.90, p = 0.98 and p = 0.91) or FCS (p = 0.97 and p = 0.85, p = 0.78 and p = 0.73), respectively.

Conclusions

Retinal and choroidal thickness in DME eyes can be quantified with good reliability, repeatability and reproducibility using new OCT devices that incorporate swept source technology. The technical advantages of this technology may provide new insights in the understanding of the choroidal changes related with DME.