Changes in choroidal blood flow velocity in patients diagnosed with central serous chorioretinopathy during follow-up for pachychoroid pigment epitheliopathy

Choroidal hemodynamics in central serous chorioretinopathy after half-dose photodynamic therapy and the effects of smoking

This retrospective study aimed to evaluate choroidal hemodynamics after half-dose photodynamic therapy (PDT) for central serous chorioretinopathy (CSC) and the effects of smoking using laser speckle flowgraphy. This study included 29 eyes of 29 patients treated with half-dose PDT for CSC, who were followed-up for at least 6 months. The mean blur rate (MBR) in the PDT irradiation area (whole area), the pachyvessel (PV) area, non-PV (NPV) area, and filling delay (FD) area were assessed at baseline and 1, 3, and 6 months post-PDT, respectively. The MBR was also assessed by smoking status. The MBR significantly decreased from baseline in the whole, PV, NPV, and FD areas at all time points (P < 0.001). Of the 29 patients, 6 were never smokers, 13 were past smokers, and 10 were current smokers. At baseline, no significant difference was found in the MBR in the whole, PV, NPV, and FD areas among never, past, and current smokers. The MBR changes showed a significantly smaller decrease in current smokers than in never smokers in the whole (P = 0.021), PV (P = 0.009), and NPV (P = 0.034) areas, but not in the FD area (P = 0.172). Half-dose PDT for CSC reduced choroidal blood flow in the PDT-irradiated area, which was blunted by current smoking status.

Hydrodynamic Analysis of the Clinical Findings in Pachychoroid-Spectrum Diseases

We wish to demonstrate that theorems of fluid dynamics may be employed to hydrodynamically analyze the clinical presentations seen within the pachychoroid-spectrum diseases (PSD). Methods: We employed both the Equation of Continuity Q = A · V in which Q represents blood flow volume, A the sectional area of a vessel, and V blood flow velocity as well as Bernoulli’s Principle 1/2 V² + P/ρ = constant where V represents blood flow velocity, P static blood pressure and ρ blood density. The Equation of Continuity states that a decrease in flow volume occurs simultaneously with a decrease in the flow velocity and/or sectional area, and vice versa. Bernoulli’s Principle states that a decrease in the velocity of a fluid occurs simultaneously with an increase in static pressure, and vice versa. Results: Hyperpermeability of the choriocapillaris, as visualized on fluorescein angiography and indocyanine green angiography (ICGA), causes a fluid exudation and, therefore, a decrease in the blood flow volume Q which elicits a simultaneous decrease in the blood flow velocity V clinically observable in filling delay into the choriocapillaris on ICGA. An increase in the static blood pressure P will simultaneously occur in venules in accord with Bernoulli’s Principle. Conclusions: A decrease in the blood flow velocity in the choriocapillaris due to its hyperpermeability will hydrodynamically elicit an increase in the blood pressure in venules. This blood pressure rise may expand Sattler and Haller veins, forming pachyveins. The primary lesion of PSD can be in pigment epithelium and choriocapillaris.

Imaging-based Assessment of Choriocapillaris: A Comprehensive Review

PURPOSE

Over the past two decades, advancements in imaging modalities have significantly evolved the diagnosis and management of retinal diseases. Through these novel platforms, we have developed a deeper understanding of the anatomy of the choroidal vasculature and the choriocapillaris. The recently developed tools such as optical coherence tomography (OCT) and OCT angiography (OCTA) have helped elucidate the pathological mechanisms of several posterior segment diseases. In this review, we have explained the anatomy of the choriocapillaris and its close relationship to the outer retina and retinal pigment epithelium.

METHODS

A comprehensive search of medical literature was performed through the Medline/PubMed database using search terms: choriocapillaris, choroid, quantification, biomarkers, diabetic retinopathy, age-related macular degeneration, choroidal blood flow, mean blur rate, flow deficit, optical coherence tomography, optical coherence tomography angiography, fluorescein angiography, indocyanine green angiography, OCTA, Doppler imaging, uveitis, choroiditis, white dot syndrome, tubercular serpiginous-like choroiditis, choroidal granuloma, pachychoroid, toxoplasmosis, central serous chorioretinopathy, multifocal choroiditis, choroidal neovascularization, choroidal thickness, choroidal vascularity index, choroidal vascular density, and choroidal blood supply. The search terms were used either independently or combined with choriocapillaris/choroid.

RESULTS

The imaging techniques which are used to qualitatively and quantitatively analyze choriocapillaris are described. The pathological alterations in the choriocapillaris in an array of conditions such as diabetes mellitus, age-related macular degeneration, pachychoroid spectrum of diseases, and inflammatory disorders have been comprehensively reviewed. The future directions in the study of choriocapillaris have also been discussed.

CONCLUSION

The development of imaging tools such as OCT and OCTA has dramatically improved the assessment of choriocapillaris in health and disease. The choriocapillaris can be delineated from the stromal choroid using the OCT and quantified by manual or automated methods. However, these techniques have inherent limitations due to the lack of an anatomical distinction between the choriocapillaris and the stromal choroid, which can be overcome with the use of predefined segmentation slabs on OCT and OCTA. These segmentation slabs help in standardizing the choriocapillaris imaging and obtain repeatable measurements in various conditions such as diabetic retinopathy, age-related macular degeneration, pachychoroid spectrum, and ocular inflammations. Additionally, Doppler imaging has also been effectively used to evaluate the choroidal blood flow and quantifying the choriocapillaris and establishing its role in the pathogenesis of various retinochoroidal diseases. As tremendous technological advancements such as wide-field and ultra-wide field imaging take place, there will be a significant improvement in the ease and accuracy of quantifying the choriocapillaris.

Correlation Between Laser Speckle Flowgraphy and OCT-Derived Retinal and Choroidal Metrics in Healthy Human Eye

Purpose

To investigate the correlation between laser speckle flowgraphy (LSFG) signals and the quantitative metrics derived from optical coherence tomography (OCT) in normal eyes.

Methods

LSFG, OCT, and OCT angiography (OCTA) imaging were performed on normal participants using a custom-designed LSFG system and a commercial swept-source OCT system. Mean (PWM) and amplitude (PWA) of the LSFG pulse waveform were selected to quantify the LSFG signals. Retinal and choroidal maps were obtained using the standard 6 × 6 mm OCT and OCTA scans. Structural and vascular metrics maps, including thickness, vessel area density, vessel skeleton density, and vessel diameter index of the retina, and choroidal thickness (CT), choroidal vessel volume (CVV) and choroidal vessel index (CVI), were employed to quantify the retinal and choroidal properties. Correlation analysis was then performed between the LSFG, retinal, and choroidal metrics maps.

Results

Twelve healthy participants aged 23 to 36 years were enrolled in this study. The spatial distribution of the PWM and PWA values was highly correlated with that of the CT and CVV metrics. On average, Spearman correlation coefficients (ρ) were 0.80 and 0.78 (all P < 0.001) for the correlations between PWM and CT and CVV, respectively, and were 0.61 and 0.63 (all P < 0.05) for the correlations between PWA and CT and CVV, respectively. In comparison, both PWM and PWA were generally weak or not correlated with all the retinal metrics and CVI.

Conclusions

LSFG signals were positively correlated with the choroidal thickness and vessel volume, suggesting choroidal blood flows dominate the LSFG signals at the area absent of large retinal vessels.

Translational Relevance

This study illustrates the dominant source of the LSFG signals in the eye.

Long-term visual and anatomic outcomes of patients with peripapillary pachychoroid syndrome

Background/Aims

To analyse the long-term anatomic and visual outcomes of patients with peripapillary pachychoroid syndrome (PPS), a recently described entity in the pachychoroid disease spectrum.

Methods

This study retrospectively included patients from several retina centres worldwide. Visual acuity (VA), retinal thickness and choroidal thickness at baseline, 6 months and final follow-up were assessed. Temporal trends in VA and anatomic characteristics were evaluated. Visual and anatomic outcomes in eyes that were observed versus those that were treated were analysed.

Results

Fifty-six eyes of 35 patients were included with mean follow-up of 27±17 months. Median VA was 20/36 at baseline and remained stable through follow-up (p=0.77). Retinal thickness significantly decreased subfoveally (p=0.012), 1.5 mm nasal to the fovea (p=0.002) and 3.0 mm nasal to the fovea (p=0.0035) corresponding to areas of increased thickening at baseline. Choroidal thickness significantly decreased subfoveally (p=0.0030) and 1.5 mm nasal to the fovea (p=0.0030). Forty-three eyes were treated with modalities including antivascular endothelial growth factor injection, photodynamic therapy, and others. VA remained stable in treated eyes over follow-up (p=0.67). An isolated peripapillary fluid pocket in the outer nuclear layer was characteristic of PPS.

Conclusion

Patients with PPS experienced decreased retinal oedema and decreased choroidal thickening throughout the course of disease. While some patients experienced visual decline, the overall visual outcome was relatively favourable and independent of trends in retinal or choroidal thickening.

Current diagnosis and management strategies in pachychoroid spectrum of diseases (Review)

This review presents a systematic analysis of the literature regarding the pachychoroid disease spectrum nomenclature, diagnosis criteria and therapeutic options. Pachychoroid related diseases are a new concept, introduced into the ophthalmological nomenclature in 2013 and evolving both as concept and as classification since then. The six disorders included in this phenotype have some common characteristics (thick choroid, pachyvessels, attenuation of the choriocapillaris), but also show individual features. The classification of the pachychoroid spectrum was revised many times, with the recent addition of the focal choroidal excavation (FCE) and peripapillary pachychoroid syndrome (PPS). As the terminology is developing, so is the number of case reports and case series from the initial report in 2013 to 57 reports in 2019. This review takes into account both the current literature and the clinical experience of the authors, emphasizing the understanding of the pathogenesis and aiming to update the therapeutic options available.

Time Course in Ocular Blood Flow and Pulse Waveform in a Case of Ocular Ischemic Syndrome with Intraocular Pressure Fluctuation

We report on a 70-year-old Japanese man with complaints of worsening left visual acuity who was diagnosed with ocular ischemic syndrome (OIS) associated with internal carotid artery (ICA) stenosis. A gonioscopy examination showed rubeosis iridis and elevated intraocular pressure (IOP) in the left eye (50 mmHg) at the baseline visit. The optic nerve head (ONH) and choroidal blood flow measured by laser speckle flowgraphy (LSFG) was impaired in the left eye compared with that in the right eye. Additionally, the blowout score (BOS), which indicates the variation of the mean blur rate (MBR) during systolic and diastolic periods, was decreased in the left eye. After treatment with an injection of bevacizumab and administration of Rho-associated kinase-inhibitor ripasudil eye drops, both ocular blood flow and BOS in each vascular bed gradually increased along with IOP reduction. The visual acuity also improved. The current case demonstrated increased blood flow and decreased fluctuation of blood flow in the ONH and choroid before and after the treatment in OIS with rubeosis iridis. The LSFG technique is useful to non-invasively assess the ocular circulation and pulse waveform in OIS.