Spectral-domain Optical Coherence Tomography Retinal and Choroidal Thickness Metric Repeatability in Age-related Macular Degeneration

Optical coherence tomography (OCT) and OCT-angiography in syndromic versus non-syndromic USH2A-associated retinopathy

PURPOSE

To compare non-syndromic and syndromic forms of USH2A-related retinitis pigmentosa (RP) by means of structural optical coherence tomography (OCT) and OCT-angiography (OCTA).

METHODS

Observational, cross-sectional, multicenter study. All patients underwent best corrected visual acuity (BCVA) measurement, OCT (Spectralis HRA + OCT, Heidelberg Engineering) and OCTA (OCT DRI Topcon Triton, Topcon Corporation). We compared subfoveal choroidal thickness (SCT), choroidal vascularity index (CVI), presence of cystroid macular edema (CME), macular vessel density (VD) at the superficial and deep capillary plexa, as well as VD of the radial peripapillary capillary (RPC) network, between syndromic and non-syndromic patients with USH2A-associated retinopathy.

RESULTS

Thirty-four eyes from 18 patients (7 females) were included. Thirteen patients (72.2%) were affected by Usher syndrome type 2, whereas the remaining 5 subjects (27.8%) had non-syndromic retinitis pigmentosa (nsRP). Syndromic patients were younger than nsRP (p = 0.01) and had a worse visual acuity than those with the exclusively retinal phenotype. Patients with Usher syndrome type 2 had a higher prevalence of CME and a thicker choroid compared to nsRP, although these results were not statistically significant (p = 0.775 and p = 0.122, respectively). Similarly, none of the other quantitative OCT and OCTA parameters was statistically different between the two groups.

CONCLUSIONS

Despite their younger age, patients with Usher syndrome type 2 displayed similar choroidal and microvascular changes compared to those with nsRP.

Diurnal variation of optical coherence tomography-based macular fluid in exudative age-related macular degeneration

BACKGROUND

Significant diurnal fluctuation of optical coherence tomography (OCT)-based macular fluid occurs in patients with several macular conditions including diabetic macular edema (DME) and cystoid macular edema due to retinal venous occlusion (RVO). OCT imaging and analysis of macular fluid status plays a central role in clinical management of exudative age-related macular degeneration (eAMD), however diurnal variation of eAMD OCT findings has not yet been formally studied. Herein, we investigate whether clinically meaningful fluctuation of OCT-based macular fluid occurs in patients with eAMD.

METHODS

Prospective observational study. Patients with eAMD and intra- and/or sub-retinal fluid on early AM OCT were enrolled to receive two consecutive OCT scans at least four hours later. Retinal layers were manually segmented on all OCT rasters and AM-to-PM and PM-to-PM image pairs were analyzed for total retinal and neurosensory retinal volume changes within the central 1 and 3 mm ETDRS subfields. Finally, two masked retinal specialists analyzed all OCT image pairs for qualitative differences that may impact clinical management.

RESULTS

21 patients with eAMD and fluid on OCT were recruited between January 2020 and November 2021. There was no mean difference between AM and PM central 3 mm total retinal volume (p = 0.56), central 3 mm neurosensory retinal volume (p = 0.25), central 1 mm total retinal mean thickness (p = 0.96), or central 1 mm neurosensory retinal mean thickness (p = 0.63), nor were any differences identified in PM-to-PM control comparisons. Qualitative analysis by two masked experts identified no clinically significant differences between any AM-to-PM OCT image pairs.

CONCLUSIONS

No significant diurnal variation in OCT-based macular fluid or thickness was identified in patients with eAMD, either quantitatively or qualitatively.

Measurement of Foveal Retinal Thickness in Myopic Patients Using Different Display Modes on Optical Coherence Tomography: A Retrospective, Cross-Sectional Study

INTRODUCTION

The aim of this work is to investigate the differences in the measurement of foveal retinal thickness in myopic patients between two display modes (1:1 pixel and 1:1 micron) on optical coherence tomography (OCT).

METHODS

Horizontal OCT line scan through the central fovea was used for manual measurement of foveal retinal thickness under the two display modes, and the values were compared using Wilcoxon signed-rank test. Correlations between the OCT image tilting angle (OCT ITA) and differences in OCT measurement were analyzed by Spearman's test.

RESULTS

127 participants with a median age of 28 years, a median spherical equivalent (SE) of - 8.5 D, and a median axial length (AL) of 27.04 mm. There were significant differences between the two display modes, with a median absolute difference (median relative difference) of 13.33 μm (2.75%) for the central foveal thickness (CFT), 5.33 μm (1.28%) for the Henle fiber and outer nuclear layer thickness (HFL + ONL), 3 μm (6.47%) for the external limiting membrane to ellipsoid zone distance (ELM-EZ), and 4 μm (8.77%) for the ellipsoid zone to retinal pigment epithelium distance (EZ-RPE) (all p < 0.05). The differences in foveal retinal thickness between the two display modes were significantly correlated with the OCT ITA (r = 0.732 for CFT, 0.561 for HFL + ONL, 0.642 for ELM-EZ, and 0.471 for EZ-RPE, all p < 0.05).

CONCLUSIONS

Disparities between the two display modes were found in the manual measurement of foveal retinal thickness and correlated to the OCT ITA.

Repeatability and reproducibility of manual choroidal thickness measurement using Lenstar images in children before and after orthokeratology treatment

PURPOSE

To investigate the repeatability and reproducibility of choroidal thickness measurements using Lenstar images in young myopic children before and after one-month orthokeratology (ortho-k) treatment.

METHOD

Ocular biometry of 39 subjects were performed using the Lenstar 900. The first five measurements with maximum differences of 0.02 mm in axial length in the right eyes were saved and used for measurement of choroidal thickness. Subfoveal choroidal thickness were manually measured by identifying the signals from the retinal pigmented epithelium layer and chorioscleral interface. Repeatability was determined by comparing measurements of the same images made by the same observer on two separate occasions (four weeks apart), while reproducibility was calculated by comparing measurements of the same images made by two independent observers. Data was analysed using intra-class correlation coefficients (ICC) and non-parametric Bland and Altman plots.

RESULTS

The choroidal peaks could not be identified in all five measurements in all subjects. On average, only 71% subjects had at least four definable images. Compared with the use of fewer than four images, reliability using an average of four definable images improved statistically, but remained clinically unacceptable (>10 µm), although pre- and post-ortho-k ICC values were good to excellent for repeatability (0.867 and 0.975, respectively) and excellent and good for reproducibility (0.959 and 0.868, respectively). Non-parametric pre- and post-ortho-k limits of agreement (2.5% and 97.5% percentiles) obtained were -45.8 to 79.3 µm and -30.3 to 9.5 µm, respectively for repeatability, and -29.0 to 33.5 µm and -21.8 to 70.0 µm, respectively for reproducibility.

CONCLUSION

Choroidal thickness measurements using the Lenstar did not show good reliability, despite the high ICC values, non-parametric Bland and Altman plots demonstrated a wide variability of measurement errors. Any changes in subfoveal choroidal thickness, measured by Lenstar, of <80 µm may not represent real changes.

Macular Choroidal Thickness Changes in Development, Progression, and Spontaneous Resolution of Epiretinal Membrane

BACKGROUND AND OBJECTIVE

To evaluate the association between macular choroidal thickness and the development, progression, and resolution of epiretinal membrane (ERM).

PATIENTS AND METHODS

The patients (n = 38) with unilateral ERM eyes with definitive changes on optical coherence tomography (OCT) and healthy fellow eyes were observed retrospectively. ERM eyes were divided into three groups: Development/new-onset group (n = 14), progression group (n = 13), and resolution group (n = 11). In each group, the average changes of macular choroidal thickness over time in ERM eyes were compared with those in the fellow eyes RESULTS: Choroidal thickness significantly decreased from 174.0 μm at baseline to 132.3 μm at event time (P = .001) in the development group, and from 140.0 μm ± 30.0 μm to 120.5 μm (P = .002) in the progression group. Conversely, a significant increase in choroidal thickness was observed in the resolution group (from 205.2 μm to 222.6 μm; P = .004). The fellow eyes showed no significant changes in choroidal thickness in all three groups.

CONCLUSION

Choroidal thinning in newly developed or significantly progressed ERM eyes and choroidal thickening in spontaneously resolved ERM eyes suggest a clinical implication of choroidal changes in ERM. [Ophthalmic Surg Lasers Imaging Retina. 2019;50:627-634.].

Weekly Changes in Axial Length and Choroidal Thickness in Children During and Following Orthokeratology Treatment With Different Compression Factors

Purpose

To determine the influence of compression factor upon changes in axial length and choroidal thickness during and following orthokeratology treatment.

Methods

Orthokeratology lenses of different compression factors (one eye with 0.75 D and the fellow eye with 1.75 D) were randomly assigned to 28 subjects (median [range] age: 9.3 [7.8–11.0] years). Ocular biometrics were measured weekly for 1 month of lens wear and after lens cessation until the refraction stabilized (mean duration: 2.8 ± 0.4 weeks). Changes between eyes, and the associations between axial shortening and choroidal thickening with other ocular biometrics were analyzed.

Results

There were no significant between-eye differences in the changes of ocular biometrics (all P > 0.05). After adjusting for paired-eye data, axial length initially decreased by 26 ± 41 μm (P = 0.03) at week 1, then gradually returned to its original length. An approximate antiphase relationship of choroidal thickness (mean change: 9 ± 12 μm, P < 0.001) with axial length was observed. A significant rebound in axial length, but not choroidal thickness, occurred during the cessation period. Central corneal thinning and choroidal thickening accounted for 70% of initial axial shortening.

Conclusions

Increasing the compression factor by 1.00 D did not affect changes in ocular biometrics in short-term orthokeratology. Significant axial shortening and choroidal thickening were observed during early treatment period. Axial shortening could not be entirely explained by central corneal thinning and choroidal thickening, which warrants further investigation.

Translational Relevance

Initial axial shortening in orthokeratology is transient and therefore axial length remains useful for long-term monitoring of axial elongation in children.

Repeatability of choroidal thickness measurements with Spectralis OCT images

Objective

To investigate the repeatability of choroidal thickness measurements determined from enhanced depth imaging optical coherence tomography (EDI-OCT) images of eyes after wearing single-vision spectacles (SV) and orthokeratology (ortho-k) lenses.

Methods and analysis

Two EDI-OCT images of 40 children (SV: 20, ortho-k: 20) taken at a single visit were analysed twice. Subjects in the ortho-k group had been wearing ortho-k for 1–4 weeks. The choroidal thickness was determined from each image using a graph theory-based software and, where appropriate, manual correction of choroidal boundaries was undertaken by an experienced examiner.

Results

The mean (±SD) choroidal thickness was 227.3±42.2 µm for the SV subjects and 251.1±54.4 µm for the ortho-k subjects. The interimage differences in choroidal thickness were −0.99±3.54 and −1.14±5.03 µm for the SV and ortho-k subjects, respectively, and the limits of agreement were +5.96 to −7.93 and +8.72 to −11.00 µm, respectively.

Conclusion

The coefficients of repeatability of choroidal thickness measurements from two EDI-OCT images taken at a single visit were 7.08 µm (SV) and 10.06 µm (ortho-k), suggesting that a change in choroidal thickness of less than 10 µm may not indicate a real change resulting from ortho-k lens wear.

Comparison of choroidal vessel thickness in children and adult eyes by enhanced-depth imaging optical coherence tomography imaging

AIM

To evaluate choroidal thickness, medium choroidal vessel thickness (MCVT) and large choroidal vessel thickness (LCVT) in normal children and adult subjects.

METHODS

Manual measurements of subfoveal choroidal thickness (SFCT), MCVT and LCVT at subfoveal and 750 µm nasal and temporal to fovea locations were completed on enhanced-depth imaging optical coherence tomography (EDI-OCT) scans of normal children and adult subjects.

RESULTS

Fifty adult and fifty-seven child subjects were included in the study (including 80 adult and 103 child eyes). Mean (±SD) SFCT of adult and children eyes in the study was 309.3±95.7 µm and 279.3±50.4 µm respectively. SFCT and subfoveal MCVT in adult eyes were significantly more than children (P=0.01 and P≤0.0001 respectively).

CONCLUSION

There is choroidal thickening with associated thickening of medium choroidal vessels in adults, suggesting that there is alteration in choroidal vasculature with ageing.

Macular Fluid Reduces Reproducibility of Choroidal Thickness Measurements on Enhanced Depth Optical Coherence Tomography

PURPOSE

To determine if different types of retinal fluid in the central macula affect the reproducibility of choroidal thickness (CT) measurements on enhanced depth imaging optical coherence tomography (EDI-OCT).

DESIGN

Retrospective reliability analysis.

METHODS

EDI-OCT images were obtained and the choroidal-scleral junction was analyzed through semiautomated segmentation. CT was measured at the fovea and averaged across the central 3-mm horizontal segment. Demographic data, central macular thickness, and type of fluid present were recorded. Intragrader and intergrader repeatability were assessed using the intraclass correlation coefficient (ICC) and coefficient of repeatability (CR).

RESULTS

Of 124 eyes analyzed, 60 (48.4%) had diabetic macular edema, 32 (25.8%) had neovascular age-related macular degeneration, and 32 (25.8%) had other causes of fluid. Intergrader ICC (CR) was 0.95 (74.1 μm) and 0.96 (63.9 μm) for subfoveal and average CT, respectively. CR was similar across various causes of retinal fluid, but was worst for subretinal fluid compared to intraretinal or sub-retinal pigment epithelial fluid. CR also worsened with increasing choroidal thickness, but was not affected by retinal thickness. Intragrader repeatability was generally greater than intergrader values, and followed the same trend.

CONCLUSIONS

The presence of macular fluid reduces CT measurement reproducibility, particularly in eyes with subretinal fluid and greater choroidal thickness. A difference of 74.1 μm in subfoveal CT or 63.9 μm in average CT may be necessary to detect true clinical change in eyes with macular fluid.

Impact of retinal pigment epithelium pathology on spectral-domain optical coherence tomography-derived macular thickness and volume metrics and their intersession repeatability

BACKGROUND

To determine the impact of retinal pigment epithelium (RPE) pathology on intersession repeatability of retinal thickness and volume metrics derived from Spectralis spectral-domain optical coherence tomography (Heidelberg Engineering, Heidelberg, Germany).

DESIGN

Prospective cross-sectional single centre study.

PARTICIPANTS

A total of 56 eyes of 56 subjects were divided into three groups: (i) normal RPE band (25 eyes); (ii) RPE elevation: macular soft drusen (13 eyes); and (iii) RPE attenuation: geographic atrophy or inherited retinal diseases (18 eyes).

METHODS

Each subject underwent three consecutive follow-up macular raster scans (61 B-scans at 119 μm separation) at 1-month intervals.

MAIN OUTCOME MEASURES

Retinal thicknesses and volumes for each zone of the macular subfields before and after manual correction of segmentation error. Coefficients of repeatability (CR) were calculated.

RESULTS

Mean (range) age was 57 (21-88) years. Mean central subfield thickness (CST) and total macular volume were 264 and 258 μm (P = 0.62), and 8.0 and 7.8 mm³ (P = 0.31), before and after manual correction. Intersession CR (95% confidence interval) for CST and total macular volume were reduced from 40 (38-41) to 8.3 (8.1-8.5) and 0.62 to 0.16 mm³ after manual correction of segmentation lines. CR for CST were 7.4, 23.5 and 66.7 μm before and 7.0, 10.9 and 7.6 μm after manual correction in groups i, ii and iii.

CONCLUSIONS

Segmentation error in eyes with RPE disease has a significant impact on intersession repeatability of Spectralis spectral-domain optical coherence tomography macular thickness and volume metrics. Careful examination of each B-scan and manual adjustment can enhance the utility of quantitative measurement. Improved automated segmentation algorithms are needed.

Repeatability of swept-source optical coherence tomography retinal and choroidal thickness measurements in neovascular age-related macular degeneration

BACKGROUND

The aim was to determine the intrasession repeatability of swept-source optical coherence tomography (SS-OCT)-derived retinal and choroidal thickness measurements in eyes with neovascular age-related macular degeneration (nAMD).

METHODS

A prospective study consisting of patients with active nAMD enrolled in the Distance of Choroid Study at Moorfields Eye Hospital, London. Patients underwent three 12×9 mm macular raster scans using the deep range imaging (DRI) OCT-1 SS-OCT (Topcon) device in a single imaging session. Retinal and choroidal thicknesses were calculated for the ETDRS macular subfields. Repeatability was calculated according to methods described by Bland and Altman.

RESULTS

39 eyes of 39 patients with nAMD were included with a mean (±SD) age of 73.9 (±7.2) years. The mean (±SD) retinal thickness of the central macular subfield was 225.7 μm (±12.4 μm). The repeatability this subfield, expressed as a percentage of the mean central macular subfield thickness, was 23.2%. The percentage repeatability of the other macular subfields ranged from 13.2% to 28.7%. The intrasession coefficient of repeatability of choroidal thickness of the central macular subfield was 57.2 μm with a mean choroidal thickness (±SD) of 181 μm (±15.8 μm).

CONCLUSIONS

This study suggests that a change >23.2% of retinal thickness and 57.2 μm choroidal thickness in the central macular subfield is required to distinguish true clinical change from measurement variability when using the DRI OCT-1 device to manage patients with nAMD.