These authors contributed equally: S. Magdalena Langner and Jan H. Terheyden.
Cerebral small vessel disease (CSVD) is associated with hypertension, hypercholesterolemia and obesity and a risk factor for stroke, vascular cognitive impairment and depression, thus contributing considerably to global mortality[
Cerebral small vessels are difficult to assess using even high-resolution MRI. Thus, diagnostic markers used are downstream cerebral changes caused by the resulting ischemia including periventricular and subcortical white matter lesions (WML) which can be detected and quantified on MRI[
The retina is much easier accessible for imaging and allows for the non-invasive, high-resolution assessment of neuronal tissue using e.g. optical coherence tomography (OCT)[
Therefore, we here assessed the association of WML on MRI with structural OCT parameters and provide information on the extend and characteristics of macular and optic disc changes in all retinal layers in CSVD to identify markers, which might help to detect this disease at an earlier stage.
36 eyes of 36 participants (27 participants with CSVD and 9 controls) were included in the analysis (Table 1). After screening of 62 individuals initially, 26 subjects were excluded due to retinal pathology (n = 18 subjects), age (n = 7 controls could not be age-matched within 5 years to patients), cerebral WML other than CSVD (n = 1) and poor OCT image quality (n = 2 scans). 19% of our participants were classified as cognitively impaired. 14 participants (39%) were imaged with a 1.5 T MRI device and 22 participants (61%) with 3 T MRI device (Table 1).
Table 1 Demographic variables and imaging parameters of patients and controls.
Total CSVD controls Age matched CSVD Gender (m/f) 15/21 12/15 3/6 4/5 0.641 0.730 MRI (1.5 T/3 T) 22/14 17/10 5/4 6/3 0.747 0.730 Fazekas (score 0/1/2/3) 9/14/10/3 0/14/10/3 9/0/0/0 0/5/4/0 Fazekas (median; IQR) 1; 2 1; 1 0;0 1; 1 Age (years) 63 ± 10 65 ± 11 57 ± 5 57 ± 4 0.073 1.000 MoCA 25 ± 4 25 ± 4 25 ± 3 26 ± 3 0.971 0.436 Cognitively impaired 19% 22% 11% 11% WMRI 0.408 ± 0.663 0.536 ± 0.724 0.025 ± 0.027 0.232 ± 0.292 NOL 14 ± 9 17 ± 9 6 ± 6 13 ± 9 Total retina volume (mm3) 2.32 ± 0.01 2.31 ± 0.11 2.36 ± 0.07 2.31 ± 0.08 0.101 0.136
Values are mean ± SD and the volume of the retina corresponds to the foveal and parafoveal volumes (3-mm-circle). *Mann–Whitney-U-test was performed to compare the groups. P1, comparison between all patients and controls; P2, comparison between age matched patients and control. Significant results (p < 0.05) are displayed in bold. CSVD, patients with cerebral small vessel disease; MRI, device used for MRI imaging; 1.5 T, Philips Ingenia 1.5 T; 3 T, Achieva TX 3 T, m, male; f, female; Fazekas, Fazekas score; IQR, interquartile range; MoCA, Montreal Cognitive Assessment; WMRI, white matter lesions volume ratio index; NOL, number of white matter lesions.
As expected, patients with CSVD had significantly more WML (p < 0.001) and higher WML volume ratio index (WMRI) (p < 0.0001) compared to control participants. However, the patient group was noticeably older than the control group which is why we performed an age-matched subgroup analysis (see below). The ganglion cell layer (GCL) volume was significantly lower in patients with CSVD compared to controls (0.31 ± 0.04 versus 0.34 ± 0.02, p = 0.032). Neither the other OCT parameters nor the Montreal Cognitive Assessment (MoCA) score were significantly different between patients and controls. In the receiver operating characteristic (ROC) analysis, the GCL volume was significantly associated with CSVD disease status (AUC 0.743; 95%-CI 0.578, 0.908; after adjusting for age: AUC 0.790; 95%-CI 0.641, 0.939). The MoCA-score was not associated with presence of CSVD (AUC 0.506; 95%-CI, 0.302, 0.701).
In a subgroup analysis of age-matched CSVD cases (Fazekas > 0) with controls (Fazekas = 0; see Table 1) we found that GCL volume was significantly reduced in patients with CSVD compared to age-matched controls (Table 2). In the analysis of the individual retinal sectors, the parafoveal nasal, inferior and superior volumes of the GCL were significantly reduced in CSVD compared to controls (Table 2).
Table 2 Comparison of structural retinal parameters between patients with cerebral small vessel disease and age-matched controls.
Parameter Controls CSVD Foveal 0.01 ± 0.00 0.01 ± 0.00 0.730 Pf. temporal 0.08 ± 0.00 0.07 ± 0.01 0.063 IPL (mm3) 0.28 ± 0.02 0.27 ± 0.02 0.094 INL (mm3) 0.27 ± 0.02 0.27 ± 0.02 1.00 OPL (mm3) 0.22 ± 0.06 0.20 ± 0.02 0.340 ONL (mm3) 0.51 ± 0.06 0.55 ± 0.03 0.094 RPE (mm3) 0.11 ± 0.02 0.10 ± 0.02 0.387 pRNFL (µm) 75 ± 6 72 ± 4 0.222 MRW (µm) 341 ± 66 333 ± 65 0.796
Values are mean ± SD and the volumes of the macular layers correspond to the foveal and parafoveal volumes (3-mm-circle). *Mann–Whitney-U-test was performed to compare the two groups. Significant results (p < 0.05) are displayed in bold. CSVD, patients with cerebral small vessel disease; GCL, ganglion cell layer; pf., parafoveal; IPL, inner plexiform layer; INL, inner nuclear layer; OPL, outer plexiform layer; ONL, outer nuclear layer; RPE, retinal pigment epithelium; pRNFL, peripapillary retinal nerve fiber layer; MRW, Bruch's membrane opening-minimum rim width.
In a subgroup analysis of CSVD cases only, the WMRI was associated with an increase in volume of the foveal outer plexiform layer (OPL). A decrease of the inner plexiform layer (IPL), the pRNFL and Bruch's membrane opening-minimum rim width (MRW) were significantly associated with a higher WMRI (Table 3 and Supplementary Table 1). After adjusting for age, an increase in the foveal OPL and a decrease in the peripapillary MRW and pRNFL were significantly associated with a higher WMRI (Table 3 and Supplementary Table 1). In age-adjusted multivariable linear regression using backward elimination, foveal OPL volume (β = 81.799; 95%-CI 21.927, 141.671; p = 0.01), temporal pRNFL thickness (β = − 0.021; 95%-CI − 0.039, − 0.002; p = 0.033) and age (β = 0.032; 95%-CI 0.017, 0.047; p < 0.001) remained associated with WMRI.
Table 3 Results of linear regression of structural retinal parameters and white matter lesions volume ratio index in patients with cerebral small vessel disease.
Structural retinal parameter WMRI association WMRI association, age adjusted β [95%-CI] β [95%-CI] Pf. nasal 0.106 Pf. inferior 0.059 Foveal Temporal PMB Nasal 0.234 Nasal inferior Temporal inferior PMB 0.209 Nasal superior 0.087
Associations between retinal parameters and WMRI were assessed using linear regression. Model 1: univariate regression, Model 2: multivariable regression adjusted for age. Significant associations (p < 0.05) are displayed in bold. In this table, only parameters are listed with a p value < 0.05 in at least one linear regression model. Further results are listed in the supplement. The volumes of the macular layers correspond to the foveal and parafoveal volumes (3-mm-circle). WMRI, white matter lesions volume ratio index; β, standardized coefficient; CI, confidence interval; IPL, inner plexiform layer; pf., parafoveal; OPL, outer plexiform layer; pRNFL, peripapillary retinal nerve fiber layer; PMB, papillo-macular bundle; MRW, Bruch's membrane opening-minimum rim width.
Most of the peripapillary MRW-locations and both peripapillary (pRNFL) and macular layers (IPL, outer nuclear layer, OPL) were significantly associated with the number of WML (NOL) (Table 4 and Supplementary Table 2). After adjusting for age, GCL, IPL and OPL volumes as well as MRW and pRNFL thickness were significantly associated with NOL (Table 4 and Supplementary Table 2). In stepwise multivariate linear regression foveal GCL volume (β = − 1266.561; 95%-CI − 1901.908, − 631.215; p < 0.001), temporal inferior MRW (β = − 0.111; 95%-CI − 0.159, − 0.062; p < 0.001), temporal MRW (β = 0.057; 95%-CI 0.004, 0.109; p = 0.037) and age (β = 0.547; 95%-CI 0.349, 0.746; p < 0.001) remained associated with NOL.
Table 4 Results of linear regression of structural retinal parameters and number of white matter lesions in patients with cerebral small vessel disease.
Structural retinal parameter NOL association NOL association, age adjusted β [95%-CI] β [95%-CI] Pf. superior − 99.825 [− 243.197, 43.547] 0.164 Total volume − 72.052 [− 159.997, 15.894] 0.104 Foveal − 591.667 [− 1671.649, 488.315] 0.270 Pf. nasal − 269.435 [− 635.884, 97.014] 0.142 Pf. nasal Pf. inferior Foveal Pf. superior 268.754 [− 25.311, 562.819] 0.071 Pf. superior − 173.958 [− 433.211, 85.294] 0.179 N/T 15.701 [− 2.940, 34.341] 0.095 Temporal PMB − 0.481 [− 0.993, 0.030] 0.064 Temporal superior Total Nasal Nasal inferior Temporal inferior Temporal PMB − 0.042 [− 0.085, 0.000] 0.050 Temporal superior − 0.039 [− 0.083, 0.006] 0.085 Nasal superior
Associations between retinal parameters and NOL were assessed using linear regression. Model 1: univariate regression, Model 2: multivariable regression adjusted for age; significant associations (p < 0.05) are displayed in bold. In this table, only parameters are listed with a p value < 0.05 in at least one linear regression model. Further results are listed in the supplement. The volumes of the macular layers correspond to the foveal and parafoveal volumes (3-mm-circle). NOL, number of white matter lesions; β, standardized coefficient; CI, confidence interval; pf., parafoveal; GCL, ganglion cell layer; IPL, inner plexiform layer; OPL, outer plexiform layer; ONL, outer nuclear layer; pRNFL, peripapillary retinal nerve fiber layer; N/T, ratio nasal to temporal; PMB, papillo-macular bundle; MRW, Bruch's membrane opening-minimum rim width.
In this study we found that peripapillary and macular OCT parameters, most prominently the GCL, were associated with both the extent of CSVD lesions on MRI as well as reduced in comparison to controls without CSVD. These results support a relationship of retinal structural parameters and cerebral changes in CSVD and may be useful in the detection and staging of CSVD. Further studies are needed to better characterize this relationship.
Our findings are in agreement with published studies. Aggarwal et al. reported a significant reduction of ganglion cells in patients with chronic non‐arteritic anterior ischemic optic neuropathy[
Interestingly, we found an OPL volume increase in association with a higher WMRI and a higher NOL. OPL thickening could be found as well in two studies which compared patients with Parkinson's disease to controls[
The absence of any difference in pRNFL thickness between patients and controls in our study is in contrast to two studies which investigated patients with Cerebral Autosomal Dominant Arteriopathy with Subcortical Infarcts and Leukoencephalopathy (CADASIL) and reported RNFL thickness to be reduced compared to controls[
The strengths of this study include the thorough screening for concurrent neurological or ocular comorbidities, the use of high-resolution MRI, a complete ophthalmic assessment, the use of state-of-the-art high-resolution SD-OCT imaging including novel read-outs corrected for ocular anatomy such as MRW and the use of standardized and published automated image analysis for both MRI and OCT. To date, this study is the first to investigate structural retinal changes considering all layers assessed by OCT in patients with CSVD after few studies assessed single-layer structural changes or structural and flow changes within the retinal vasculature[
Non-neurological and non-ocular comorbidities were not assessed which might have affected our findings. One patient had a meningioma which had no influence on the evaluation of the Fazekas score or on the lesion segmentation and assumingly did not affect OCT measurements based on its localization. A further limitation is the time lag between MR-and OCT-imaging which might have led to an underestimation of effect size as cerebral CVSD lesions might have progressed in the meantime. We did not correct for multiple testing as this was an exploratory study, which might lead to spurious associations. Thus, any findings need confirmation in additional studies.
In conclusion, several retinal structural changes are present in CSVD patients, related to the extent of the cerebral changes and independent of their age. Many of these changes are unspecific in isolation but future studies may succeed in identifying a specific profile of retinal changes able to aid in the detection and monitoring of CSVD.
A total of 62 subjects (44 patients with CSVD and 18 control participants without CSVD or ocular diseases) were recruited from a database of the Department of Neurology at the University Hospital Bonn for this case–control study. All subjects had undergone cerebral MRI for clinical indications. The study followed the tenets of the Declaration of Helsinki and was approved by the Ethics Committee of the University Hospital Bonn (consecutive Number: 281/17). Written informed consent was obtained from all participants.
Potential participants were identified using an internal MRI database. The search algorithm included "MRI obtained between 01/01/2017 and 05/31/2019", as well as the keywords "headache," "dizziness," "syncope," "paresthesia," "exclusion of microembolization," and "exclusion of metastases".
Exclusion criteria were any eye diseases including glaucoma and retinal diseases, any opacity of the optical media interfering with retinal imaging, malignancy, major stroke, larger intracranial lesions or structural anomalies affecting the MRI analysis.
All participants underwent cognitive testing using the MoCA[
For the clinically indicated 1.5 or 3 T MRI-Imaging (Philips Ingenia 1.5 T and Achieva TX 3 T; Philips Healthcare, Best/The Netherlands) an 8-channel head coil was used.
Axial whole-brain 2D fluid-attenuated inversion recovery (FLAIR) images with a slice thickness of 6 mm, no gap and an echo time of 140 ms were evaluated for all patients. The FLAIR sequence of the 1.5 T MRI scanner had a matrix of 352 × 352, a repetition time of 11 s and an inversion time of 2800 ms. The corresponding sequence of the 3 T MRI scanner had a matrix of 512 × 512, a repetition time of 12 s and an inversion time of 2850 ms.
All patients and controls were independently evaluated and clinically diagnosed by two board certified neuroradiologists, based on the microvascular leukoencephalopathy score according to Fazekas et al.[
The lesions were automatically segmented with the LST Toolbox (version 2.0.15 for SPM12)[
Graph: Figure 1 T2 FLAIR images from a 75-year old participant with hyperintense lesions (Fazekas 3) due to cerebral small vessel disease. (A) T2 FLAIR image showing multiple hyperintense white matter lesions. (B) Results of the white matter lesions segmentation using the lesion prediction algorithm. The white matter lesions detected by the algorithm are presented in red-yellow.
All participants underwent a complete ophthalmic assessment including retinal and optic nerve head imaging using spectral domain OCT-imaging. The time interval between MRI and ophthalmic assessment was 9,5 months at median (range: 6 weeks to 20 months). Participants were imaged with non-dilated pupils, using the same OCT-device (Spectralis HRA + OCT, version 6.5.4.0, Heidelberg Engineering, Heidelberg, Germany). Reporting of OCT imaging followed the APOSTEL 2.0 guidelines[
A macular volume scan (121 horizontal B-Scans, 25 frames, 20° × 25°), and a BMO scan (3.5 mm, 4.1 mm, and 4.7 mm diameter circular scans with 100 frames and automatic placement and 24 radial scans with 25 frames each) of the optic nerve head were acquired (Fig. 2). The integrated automatic real-time function adjusts for eye movement and offers a high resolution and reproducibility[
Graph: Figure 2 Optical coherence tomography-images of 75-year old participant. (A) Macular scan—different macular layers are segmented; (B) RNFL-scan—the peripapillary retinal nerve fiber layer (pRNFL) is segmented; (C) BMO-scan—the arrows show the Bruch's membrane opening-minimum rim width (MRW). RNFL retinal nerve fiber layer, GCL ganglion cell layer, IPL inner plexiform layer, INL inner nuclear layer, OPL outer plexiform layer, ONL outer nuclear layer, RPE retinal pigment epithelium.
The right eye of each patient was chosen for analysis except cases in whom any of the exclusion criteria applied for the right eye. In those cases, the left eye was chosen. OCT images with poor quality (i.e. < 20 dB single strength) or motion artifacts were excluded, as assessed by three graders (SML, JHT, CAT). Automated segmentation was performed, using the Heidelberg Eye Explorer (HEYEX 2, Heidelberg Engineering, Heidelberg, Germany). The automated segmentation boundaries of the individual layers (Fig. 2A), the pRNFL (Fig. 2B) and the MRW (Fig. 2C) were manually verified for accuracy and corrected if needed. The volumes were measured using the Early Treatment Diabetic Retinopathy Study grid[
Data analysis was performed with IBM SPSS Statistics (version 26.0). Descriptive statistics included mean scores which were compared using the Mann–Whitney-U-test for the overall cohort and for the age-matched sub-cohort (± 5 years).
Receiver operating characteristic (ROC) analysis with and without age adjustment was performed to determine the sensitivities of retinal parameters and MoCA score to detect CSVD (based on the Fazekas score) in our cohort. Because of a positive Pearson correlation coefficient between the OPL and the WMRI, the ROC-analysis for the OPL was performed with inversed OPL values. Binary logistic regression analysis was performed to determine the regression coefficients and the constant for age adjustment. Age and other significant parameters of the non-age-adjusted ROC analysis were used as independent variables in age-adjusted ROC analysis. Because of not normally-distributed WMRI residuals, WMRI values were logarithmically transformed for parametric statistical analyses.
In a subgroup analysis of all participants with CSVD, to whom none of the exclusion criteria applied, we investigated associations between MRI (WMRI, NOL) and OCT parameters using linear regression analysis. Multivariable regression models included parameters which were significantly associated in age-adjusted linear regressions and were calculated using backward elimination. If two dependent OCT-parameters correlated > 0.80 according to Pearson, only the one with a stronger correlation was included in the model to avoid multicollinearity.
The global statistical significance level was 0.05. This study followed STROBE checklist for observational research[
This research was supported by funding of the German Scholars Organization/Else Kröner Fresenius Stiftung (GSO/EKFS 16) to RF and BONFOR GEROK Program, Faculty of Medicine, University of Bonn, Grant No. O-137.0028 to MWMW. All images included in this paper were created by the authors themselves.
R.P.F. and G.C.P. designed this study. S.M.L., C.F.G., C.K. and V.C.W.K. acquired the data. S.M.L., J.H.T., C.K., V.C.W.K., R.P.F., C.A.T., G.N.T., C.B. and M.W.M.W. analyzed and interpreted the data. S.M.L., J.H.T. and R.P.F. drafted the initial manuscript. C.F.G., C.K., V.C.W.K., C.A.T., G.N.T., C.B., M.W.M.W. and G.C.P. critically revised the manuscript. All authors approved the final manuscript and agreed to be accountable for all aspects of the work.
Open Access funding enabled and organized by Projekt DEAL.
The data that support the findings of this study are included in the Supplement. Further data are available from the corresponding author upon reasonable request.
SML, JHT, CFG, CAT, GNT: Heidelberg Engineering, Optos, Carl Zeiss Meditec, CenterVue (devices). CB, CK, VCK: none. MWMW: Heidelberg Engineering, Optos, Carl Zeiss Meditec, CenterVue, D-EYE Srl (devices); DigiSight Technologies (travel support); Heine Optotechnik (research funding, devices, travel reimbursement, consultant); Eyenuk Inc. (free analysis); ASKIN & CO GmbH (travel reimbursement, honoraria); Berlin-Chemie AG (grant, travel reimbursements). GCP: Bayer, Boehringer Ingelheim, Pfizer, BMS (sponsoring). RPF: Bayer, Novartis, Santen, Opthea, Novelion, Santhera, Inositec, Alimera, Retina Implant, Allergan, Boehringer Ingelheim (consultant); Bayer, Ellex, Alimera (research funding); Heidelberg Engineering, Optos, Carl Zeiss Meditec, CenterVue (devices).
Graph: Supplementary Information.
• BMO
- Bruch's membrane opening
• CADASIL
- Cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy
• CSVD
- Cerebral small vessel disease
• FLAIR
- Fluid-attenuated inversion recovery
• GCL
- Ganglion cell layer
• INL
- Inner nuclear layer
• IPL
- Inner plexiform layer
• LPA
- Lesion prediction algorithm
• MoCA
- Montreal cognitive assessment
• MRW
- Bruch's membrane opening-minimum rim width
• NOL
- Number of white matter lesions
• OCT
- Optical coherence tomography
• ONL
- Outer nuclear layer
• OPL
- Outer plexiform layer
• PMB
- Papillo-macular bundle
• pRNFL
- Peripapillary retinal nerve fiber layer
• ROC
- Receiver operating characteristic
• RPE
- Retinal pigment epithelium
• TIV
- Total intracranial volume
• WML
- White matter lesions
• WMRI
- White matter lesions volume ratio index
The online version contains supplementary material available at https://doi.org/10.1038/s41598-022-13312-z.
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By S. Magdalena Langner; Jan H. Terheyden; Clara F. Geerling; Christine Kindler; Vera C. W. Keil; Christopher A. Turski; Gabrielle N. Turski; Charlotte Behning; Maximilian W. M. Wintergerst; Gabor C. Petzold and Robert P. Finger
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