Subfoveal Choroidal Thickness as a Potential Predictor of Clinical Response to Stereotactic Radiotherapy for Neovascular Age-Related Macular Degeneration

In vitro evaluation of simulated stereotactic radiotherapy for wet age-related macular degeneration on three different cell lines

Low energy stereotactic radiotherapy has been proposed for the treatment of neovascular age related macular degeneration. We investigated the in vitro effect of the radiotherapy on pericytes, retinal pigment epithelium and endothelial cells. Primary human retinal pigment epithelium cells, human umbilical vein endothelial cells and human pericytes from Placenta were cultivated. In a pairwise protocol, one plate was irradiated at a dose of 16 Gy, while the second plate served as a non-irradiated control. Thereafter, cells were cultivated either in serum-free (non-permissive) or serum-stimulated (permissive) conditions. A life/dead assay, an XTT and a BrdU assay were performed up to 7 days after irradiation. No cell death occurred at any timepoint in any cell line after treatment nor in the control. Compared to the unirradiated controls, cell viability and metabolic activity were significantly reduced in irradiated cells in the XTT assay, except for non-permissive RPE cells. In the BrdU assay, proliferation was inhibited. While no cell death was detected in vitro, viability and proliferative capacity of all cell lines were significantly reduced. Therefore, it seems that low energy stereotactic radiotherapy inhibits angiogenesis without a direct induction of apoptosis but influencing microvascular function and stability.

Three-year clinical and optical coherence tomography follow-up after stereotactic radiotherapy for neovascular age-related macular degeneration

PURPOSE

The long-term clinical outcome of adjuvant stereotactic radiotherapy (SRT) in neovascular age-related macular degeneration (nAMD) patients was evaluated.

METHODS

This case-control study included patients with unilateral nAMD, who underwent SRT complementary to standard anti-VEGF treatment. Only patients with monthly follow-up over at least three years were considered. Number of intravitreal injections, visual acuity (VA), central retinal thickness (CRT), and subfoveal choroidal thickness (SFCT) were evaluated and compared to baseline as well as to an age- and gender-matched control group, who received anti-VEGF monotherapy.

RESULTS

Twenty patients were irradiated and had complete follow-up. Cumulatively, SRT patients needed significantly less injections than non-irradiated ones over three years (14 vs. 18, p ​= ​0.014), while median VA did not show statistically significant changes (0.4 logMAR at baseline to 0.65 logMAR at final follow-up, p ​= ​0.061). CRT remained steady, but SFCT showed a continuous thinning of almost 50 ​μm (p ​= ​0.031) in irradiated patients over three years. Multiple linear regression analysis revealed that SFCT and VA at time of irradiation are significant prognostic factors of VA change in SRT patients over the following three years (F(2,17) ​= ​23.946, p<0.001, R² of 0.738).

CONCLUSIONS

SRT significantly reduced the cumulative anti-VEGF treatment burden over three years, however, this was mainly driven by the results of the first year after irradiation. A thinner SFCT at time of irradiation was associated with poorer visual outcome. While further research and investigation are warranted to elucidate the underlying pathogenesis, SFCT could be a potential biomarker when evaluating a patient's suitability for SRT.

The Application of Enhanced Depth Imaging Spectral-Domain Optical Coherence Tomography in Macular Diseases

The choroid plays an essential role in the pathogenesis of various posterior segment diseases. However, traditional imaging methods still have limited cross-sectional observation of choroid. Enhanced depth imaging in spectral-domain optical coherence tomography (EDI SD-OCT) uses a closer scanning position to the eye to create an inverted SD-OCT image with the advantage of better depth sensitivity, which can observe choroidal structure and measure choroidal thickness (CT) accurately. At present, more and more choroidal thickness measurements have been made in normal and pathologic states, in order to understand the pathogenesis and differential diagnosis and prognosis of various diseases, especially for macular lesions. This paper would review relevant original literatures published from January 1, 2008, to February 1, 2020, to evaluate the relationship between the changes of CT with EDI SD-OCT and macular diseases.

Evaluating diurnal changes in choroidal sublayer perfusion using optical coherence tomography angiography

PURPOSE

To investigate diurnal changes of choroidal sublayer perfusion in normal eyes and to identify influencing factors using optical coherence tomography angiography (OCTA).

METHODS

A prospective study was conducted on healthy volunteers, each of whom underwent repeated measurements of subfoveal choroidal thickness (SFCT) via enhanced depth imaging (EDI) optical coherence tomography (OCT) as well as perfusion of choroidal vascular sublayers using OCTA at 7 a.m., 12 p.m., 4 p.m. and 8 p.m. Possible interactions between diurnal variations and other factors, such as mean arterial pressure (MAP), gender and age, were evaluated.

RESULTS

A total of 22 eyes from 22 participants were analysed. Mean age of participants was 56 years. A significant pattern of diurnal variation was observed for SFCT (p < 0.001) as well as perfusion of Sattler's layer (SLP; p = 0.009) and Haller's layer (HLP; p = 0.003). SFCT demonstrated a linear decrease, being thicker in the morning (348 μm) and thinner in the evening (310 μm). Both, SLP and HLP showed a quadratic relation to time of day, increasing from morning (64% and 76%) to afternoon (66% and 77%), before decreasing again in the evening (64% and 76%). HLP changes were significantly associated with fluctuations of MAP (B = 0.0007; CI 0.0001-0.0014; p = 0.047). No significant differences with regard to gender were detectable. However, older participants (≥60 years) had fewer diurnal changes (p = 0.042).

CONCLUSION

Optical coherence tomography angiography-based analysis of choroidal sublayer perfusion demonstrated significant diurnal variations. Therefore, it is important to account for time of day, when comparing longitudinal OCTA data.

Evaluation of choroidal substructure perfusion in patients affected by systemic sclerosis: an optical coherence tomography angiography study

Objective: Vasculopathy in systemic sclerosis (SSc) is characterized by the obliteration of arterioles and a reduced capillary density in various tissues. In SSc, atrophic alterations of the choroid have been suggested based on morphological data acquired by optical coherence tomography (OCT). In this study, we aimed to assess the choroid in eyes of patients with SSc from a microcirculatory, dynamic point of view by adding optical coherence tomography angiography (OCTA) to the diagnostic spectrum.Method: SSc patients were enrolled, and age- and gender-matched healthy subjects were used as controls. In addition to basic ophthalmological and rheumatological examinations, individuals underwent enhanced-depth imaging OCT and OCTA. Subfoveal thicknesses of the choroid as well as all three choroidal vascular sublayers were measured and submacular perfusion values were evaluated.Results: In total, 12 patients with SSc and 12 matched controls were included. The median age of participants was 64 years. Submacular perfusion was significantly lower in the choriocapillaris (Δ = 0.72%; p = 0.045), Sattler's layer (Δ = 2.87%; p = 0.001), and Haller's layer (Δ = 2.69%; p = 0.018) of SSc patients compared to controls. Subfoveal thicknesses of Sattler's layer (Δ = 15 µm; p = 0.026) and Haller's layer (Δ = 41 µm; p = 0.045) were also significantly smaller in the SSc group.Conclusion: Choroidal microcirculation is impaired in SSc, even in patients without ophthalmological symptoms. Choroidal OCT and OCTA may offer additional biomarkers for SSc activity.

Subfoveal choriocapillaris, Sattler's and Haller's layer thickness predict clinical response to stereotactic radiotherapy in neovascular age-related macular degeneration patients

Purpose

To evaluate the significance of choroidal substructure analysis in predicting the clinical response to adjuvant stereotactic radiotherapy (SRT) in neovascular age-related macular degeneration (nAMD) patients.

Methods

Patients with nAMD, who underwent SRT (baseline) in addition to common intravitreal injections (IVIs) and subsequently had at least 12 months of complete follow-up, were enrolled. In a post hoc analysis, optical coherence tomography (OCT) data were reviewed, and subfoveal choroidal thickness (CT) as well as the thickness of choroidal substructures, such as choriocapillaris (CC), Sattler's layer (SL), and Haller's layer (HL), was measured to determine if these influenced SRT efficacy.

Results

A total of 35 eyes of 35 patients were included. While each of the 4 choroidal metrics significantly forecasts the clinical response to SRT, combining them all together produced the most reliable prediction model.

Conclusion

In terms of clinical response to SRT in nAMD patients, choroidal substructure analysis does improve the quality of the prediction model when combined with subfoveal CT.