Evaluation of the Effect of Proptosis on Choroidal Thickness in Graves' Ophthalmopathy

Changes in choroidal thickness and choroidal vascularity index in thyroid eye disease: a systematic review

PURPOSE

To evaluate the evidence for changes in choroidal thickness and choroidal vascularity index (CVI) in people with thyroid eye disease (TED), stratified by severity, as measured by optical coherence tomography (OCT).

METHODS

Systematic review, including quality assessment, of published studies investigating choroidal thickness in TED. Outcomes of interest included CVI, subfoveal choroidal thickness, mean choroidal thickness, and peripheral choroidal thickness in four quadrants (superior, inferior, medial, lateral).

RESULTS

Nineteen studies were included which contained measurements from 1067 eyes in 798 patients with TED. Most studies found an increased CVI and increased choroidal thickness in patients with TED compared to normal controls, especially in the subfoveal region. In addition, several studies reported an increased thickness in patients with active vs. inactive TED, although the results are equivocal. Finally, many studies reported associations between increased choroidal thickness and worsened clinical measurements of disease activity, such as Clinical Activity Score (CAS).

CONCLUSIONS

This systematic review provided evidence for an association between increased CVI/choroidal thickness and TED, suggesting a potential for OCT-measured CVI/choroidal thickness as an objective clinical marker. Given heterogeneity, future studies are needed to assess the role of measuring the choroidal changes in diagnosis and management of TED.

A Comparison of Observational Studies on Subfoveal Choroidal Thickness Measured with OCT according to the Level of Thyroid Eye Disease Activity-Systematic Review and Meta-Analysis

This study aims to systematise subfoveal choroidal thickness (SFCT) measured using optical coherence tomography (OCT) in patients with different severities of thyroid eye disease (TED) compared with healthy subjects. The PubMed, Web of Science and Scopus databases were searched for the following terms: ((Graves' ophthalmopathy) OR (thyroid eye disease) OR (Graves' orbitopathy) OR (thyroid-associated orbitopathy)) AND (choroidal thickness) AND ((optical coherence tomography) OR (OCT)). The pool of papers was narrowed down to articles published until 31 January 2023 (26, 26 and 96 papers, respectively). Twenty-five (25) articles were taken into consideration, which were original papers and included the choroidal thickness measurements among TED patients in their results. Finally, eight papers were included in the comparative analysis of the SFCT parameter in TED patients and a group of healthy controls, and seven papers in the comparative analysis of the same parameter between active and inactive TED patients. The mean value of the difference between the TED group and the healthy group was 38.79 μm, with a confidence interval (CI) from 0.09 to 77.49 μm (p = 0.0495). The mean difference between the active TED group and inactive TED group was 38.02 μm, with a CI from 8.62 to 67.42 μm (p = 0.0113). All the results were statistically significant.

Orbital and ocular perfusion in thyroid eye disease

Thyroid eye disease (TED) is characterized by enlargement of extraocular muscles, an increase in retrobulbar fat, orbital fibrosis, and fluctuations in plasma thyroid hormone levels in most patients, often associated with raised autoantibody titers. The occurrence of orbital space conflict compromises the orbital perfusion, unchecked progression of which results in irreversible loss of visual acuity and visual fields. The quantitative assessment of orbital perfusion can be done by measurement of blood flow velocities in the superior ophthalmic vein (SOV), ophthalmic artery (OA), central retinal artery (CRA), and posterior ciliary artery by color Doppler imaging. The retinal and choroidal microvasculature is studied by optical coherence tomography and optical coherence tomography angiography. The orbital and ocular perfusion fluctuates during the course of TED. Orbital congestion is reflected by the reduction or reversal of SOV flow and an increase in subfoveal choroidal thickness. The active phase is characterized by high blood flow velocities of the OA and CRA. The onset of dysthyroid optic neuropathy is associated with reduced arterial perfusion and reduction in parafoveal and peripapillary vascular density. Orbital decompression improves the SOV flow and decreases the resistivity index of CRA. Sequential evaluation of orbital hemodynamic changes can thus supplement the clinical scoring systems for monitoring and planning intervention in TED.

Assessment of Choroidal Vascularity in Inactive Thyroid Associated Orbitopathy

Objectives

The objectives of the study were to evaluate the vascular and stromal structure of the choroid in patients with inactive thyroid associated orbitopathy (TAO) by measuring choroidal vascularity index (CVI) and choroidal thickness (CT) using enhanced depth imaging (EDI) optical coherence tomography (OCT).

Methods

The choroidal image was taken with EDI mode spectral domain (SD)-OCT. All scans were taken between 9.30 am and 11.30 am to avoid the diurnal variation of CT and CVI. To calculate CVI, macular SD-OCT scans were binarized using the publicly available software ImageJ and luminal area and total choroidal area (TCA) were measured. CVI was calculated as the proportion of LA to TCA. Furthermore, the relation between CVI and axial length, gender, and age was evaluated.

Results

This study included 78 individuals with a mean age of 51.4±7.3 years. Group 1 consisted of 44 patients with inactive stage TAO, and Group 2 consisted of 34 healthy controls. Subfoveal CT was 338.92±73.93 µm in Group 1 and 303.97±40.35 µm in Group 2 (p=0.174). The CVI significantly differed between the two groups, which was higher in group 1 (p=0.000).

Conclusion

Although CT was not different between groups, CVI which is the indicator of the vascular status of the choroid, was higher in patients with TAO in the inactive stage compared with healthy control subjects.

Can the long term using of pregabalin in fibromyalgia affect the choroid and retinal nerve fiber layer?

BACKGROUND

In this study, the effects of long-term pregabalin use on the choroid and retinal nerve fiber layer were investigated in the fibromyalgia disease.

METHODS

The patient group consisted of 41 fibromyalgia patients using pregabalin. The control group consisted of 41 newly diagnosed fibromyalgia patients who had not received any treatment yet. Choroidal and retinal nerve fiber layer thickness measurements were performed with Cirrus HD-OCT (Carl Zeiss Meditec Inc., Dublin, CA, USA) 30 minutes after pupil dilation with 1% tropicamide.

RESULTS

There was no difference in subfoveal choroidal thickness, nasal choroidal thickness and temporal choroidal thickness between the patient and control groups (p > 0.05). Increasing the duration of drug use within the patient group was found to thin the retinal nerve fiber layer (p < 0.05).

CONCLUSION

We found that pregabalin had no effect on the choroid, while it had a thinning effect for retinal nerve fiber layer. It is recommended not to be preferred pregabalin in fibromyalgia patients with retinal nerve fiber layer damage such as diabetic retinopathy and glaucoma. Patients treated with pregabalin should have regular control in the ophthalmology clinic.

Evaluation of choroidal circulation and stromal features in Graves' disease

PURPOSE

This study aimed to evaluate choroidal thickness (CT) and choroidal vascularity index (CVI) in patients with Graves' disease (GD) without ocular involvement.

METHODS

Fifty patients diagnosed with GD and 50 age and gender matched healthy control subjects were retrospectively evaluated. Measurements were taken from five different points on CT images. Choroid images were classified as lumen regions (LA) and stromal regions (SA) using the image binarization method. CVI was calculated by dividing LA by the total choroidal area (TCA). The effects of Thyrotropin Receptor Antibody (TRAb), age, GD duration, blood pressure, axial length measurements, and intraocular pressure were analyzed on CT and CVI measurements.

RESULTS

Mean age was 40.1 ± 13.5 years in the patient group and 39.3 ± 13.6 years in the control group (p = 0.89). There was no significant difference between the GD group and control group in terms of CT measurements. There was a significant difference between the mean CVI measurements of the GD group and control group (68.03 ± 3.41 and 66.62 ± 3.11, respectively) (p < 0.001). Univariate linear regression analysis revealed a positive correlation between TRAb and CVI (p = 0.013).

CONCLUSION

While there was no significant difference between the CT measurements of the GD group and the control group, the GD group had significantly higher CVI measurements.

Can the coronavirus disease 2019 (COVID-19) cause choroiditis and optic neuropathy?

Objectives: We aim to investigate the involvement of the choroid and retinal nerve fiber layer (RNFL) in COVID-19 patients using spectral domain optical coherence tomography.

Methods: This cross-sectional study was conducted between April and June 2020. 40 patients (23 female and 17 male) with COVID-19 and 42 healthy individuals (26 female and 16 male) were included in the study. The OCT scans were performed 4 weeks after the COVID-19 diagnosis.

Results: In the COVID-19 group, in the right eyes, the mean nasal choroidal thickness was 295.70 ± 7,046 μm ( p = 0.017), mean subfoveal choroidal thickness was 333.25 ± 6,353 μm ( p = 0.003), mean temporal choroidal thickness was 296.63 ± 6,324 μm ( p = 0.039), and mean RNFL was 89.23 ± 1.30 μm ( p = 0.227). In the left eyes, mean nasal choroidal thickness was 287.88 ± 9,033 μm ( p = 0.267), mean subfoveal choroidal thickness was 333.80 ± 9,457 μm ( p = 0.013), mean temporal choroidal thickness was 298.50 ± 9,158 μm ( p = 0.079), and mean RNFL was 89.48 ± 1,289 μm ( p = 0.092). Compared with the control group, the patient group had significant thickening of the choroidal thickness in all quadrants of the right eyes, and significant thickening of the subfoveal choroidal thickness in the left eyes. There was no significant difference in the RNFL thickness between groups ( p > 0.05).

Conclusion: COVID-19 may cause a subclinical involvement in the choroidal layer.