EXTENDED FIELD IMAGING OPTICAL COHERENCE TOMOGRAPHY ANGIOGRAPHY FOR THE STUDY OF RETINAL AND CHOROIDAL CHANGES AFTER RADIATION THERAPY FOR CHOROIDAL MELANOMA: Comparison With Wide-Field Angiography

Advantages of the Utilization of Wide-Field OCT and Wide-Field OCT Angiography in Clinical Practice

Wide-field (WF) retinal imaging is becoming a standard diagnostic tool for diseases involving the peripheral retina. Technological progress elicited the advent of wide-field optical coherence tomography (WF-OCT) and WF-OCT angiography (WF-OCTA) examinations. This review presents the results of studies that analyzed the implementation of these procedures in clinical practice and refers to them as traditional and ultra-wide-field fluorescein angiography (UWF-FA). A PUBMED search was performed using the terms WF-OCT OR WF-OCTA OR UWF-FA AND the specific clinical entity, and another search for diabetic retinopathy (DR), retinal vein occlusion (RVO), Coats disease, peripheral retinal telangiectasia, peripheral retinal degeneration, lattice degeneration, and posterior vitreous detachment. The analysis only included the studies in which the analyzed field of view for the OCT or OCTA exam was larger than 55 degrees. The evaluation of the extracted studies indicates that WF imaging with OCT and OCTA provides substantial information on retinal disorders involving the peripheral retina. Vascular diseases, such as DR or RVO, can be reliably evaluated using WF-OCTA with results superior to standard-field fluorescein angiography. Nevertheless, UWF-FA provides a larger field of view and still has advantages over WF-OCTA concerning the evaluation of areas of non-perfusion and peripheral neovascularization. Detailed information on the vascular morphology of peripheral changes should be obtained via WF-OCTA and not angiographic examinations. WF-OCT can serve as a valuable tool for the detection and evaluation of vitreoretinal traction, posterior vitreous detachment, and peripheral retinal degeneration, and guide therapeutic decisions on a patient's eligibility for surgical procedures.

Ultra-widefield color fundus photography combined with high-speed ultra-widefield swept-source optical coherence tomography angiography for non-invasive detection of lesions in diabetic retinopathy

Purpose

To compare the detection rate of diabetic retinopathy (DR) lesions and the agreement of DR severity grading using the ultra-widefield color fundus photography (UWF CFP) combined with high-speed ultra-widefield swept-source optical coherence tomography angiography (UWF SS-OCTA) or fluorescein angiography (FFA).

Methods

This prospective, observational study recruited diabetic patients who had already taken the FFA examination from November 2021 to June 2022. These patients had either no DR or any stage of DR. All participants were imaged with a 200° UWF CFP and UWF SS-OCTA using a 24 × 20 mm scan model. Images were independently evaluated for the presence or absence of DR lesions including microaneurysms (MAs), intraretinal hemorrhage (IRH), non-perfusion areas (NPAs), intraretinal microvascular abnormalities (IRMAs), venous beading (VB), neovascularization elsewhere (NVE), neovascularization of the optic disc (NVD), and vitreous or preretinal hemorrhage (VH/PRH). Agreement of DR severity grading based on UWF CFP plus UWF SS-OCTA and UWF CFP plus FFA was compared. All statistical analyses were performed using SPSS V.26.0.

Results

One hundred and fifty-three eyes of 86 participants were enrolled in the study. The combination of UWF CFP with UWF SS-OCTA showed a similar detection rate compared with UWF CFP plus FFA for all the characteristic DR lesions (p>0.05), except NPAs (p = 0.039). Good agreement was shown for the identification of VB (κ = 0.635), and very good agreement for rest of the DR lesions between the two combination methods (κ-value ranged from 0.858 to 0.974). When comparing the grading of DR severity, very good agreement was achieved between UWF CFP plus UWF SS-OCTA and UWF CFP plusr FFA (κ = 0.869).

Conclusion

UWF CFP plus UWF SS-OCTA had a very good agreement in detecting DR lesions and determining the severity of DR compared with UWF CFP plus FFA. This modality has the potential to be used as a fast, reliable, and non-invasive method for DR screening and monitoring in the future.

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.

Importance of Optical Coherence Tomography and Optical Coherence Tomography Angiography in the Imaging and Differentiation of Choroidal Melanoma: A Review

Simple Summary

Choroidal melanoma is a highly malignant intraocular neoplasm. It is the most prevalent intraocular tumor in adults and it derives from melanocytes; the liver is the most common site of its metastases. An early and noninvasive diagnosis is essential to enhance patients’ chances for early treatment. The OCT and OCTA-A are a noninvasive and noncontact methods used in the diagnostic process and support therapeutic decisions during control visits. These devices allow for detection and the real-time imaging of choroidal melanoma and its differentiation from metastasis and choroidal nevi. In addition to analyzing the currently utilized OCT and OCT-A methods, this review describes also the anatomy and imaging of specific vascular layers of the eye.

Abstract

Choroidal melanoma requires reliable and precise clinical examination and diagnosis to differentiate it from benign choroidal nevi. To achieve accurate diagnosis, as well as monitoring the progression of disease, various imaging modalities are used, including non-invasive optical coherence tomography (OCT) and optical coherence tomography angiography (OCTA). This review begins with a historical account of the development of OCT and OCTA and the methods of generation of images. This outlines the understanding of what OCT/OCTA images show, as well as how image artifacts arise. The anatomy and imaging of specific vascular layers of the eye are introduced. Then, anatomical aspects of choroidal melanoma, its diagnosis and differentiation from metastasis, and choroidal nevi are presented. The purpose of this review is to critically evaluate application of OCT and OCTA in the diagnosis of choroidal melanoma.

Clinical Applications of Optical Coherence Tomography Angiography in Ocular Oncology: Pearls and Pitfalls

BACKGROUND

Optical coherence tomography angiography (OCTA) is a valuable imaging tool for the diagnosis of several retinal and choroidal diseases. Its role in ocular oncology is clinically promising but still controversial. In this review, we report the main applications and limits of the use of OCTA for the study of intraocular tumors.

SUMMARY

OCTA allows a rapid, safe, low-cost, and high-resolution visualization of the retinal and choroidal vasculature. Attempts have been made to use this technology in ocular oncology to differentiate benign and malignant lesions and to assist physicians in the evaluation and monitoring of post-treatment complications. Main limitations include failure in correct segmentation due to the tumor inner profile or thickness, poor penetration of the laser into the lesion, masking effect from overlying fluid, media opacities and poor fixation.

KEY MESSAGES

The main applications of OCTA in ocular oncology consist of the documentation of tumor-associated choroidal neovascularizations and the study of vascular changes following tumor treatments. In particular, the diffusion of wide-field protocols makes OCTA suitable for the diagnosis and follow-up of radiation chorio-retinopathy, allowing a detailed visualization of both macular and peripheral ischemic changes. Optimistically, future innovations in OCTA technology may offer new perspectives in the diagnosis and follow-up of intraocular tumors.