Objectives: The aim of this study was to establish the concordance between conventional 20 Mhz ultrasonography and an ultrawide-field (UWF) imaging system (Optos^® California) in the measurement of basal diameters of melanocytic choroidal tumors. Methods: A retrospective study comparing diagnostic tests was conducted in patients with untreated melanocytic choroidal lesions (either nevus or melanoma) who had undergone both UWF imaging and ultrasonography. Only cases with a clear visualization of tumor borders in both imaging modalities were included. Longitudinal and transversal base diameters of the melanocytic tumors were measured by 20 MHz US (one observer) and UWF fundus photography (two observers). Interobserver agreement was assessed for UWF imaging first to validate the technique. Then, UWF imaging measurements were compared with 20 MHz US results. Results: In total, 106 patient images were reviewed, of which 61 were excluded due to unclear visualization of tumor margins. We found excellent concordance (from ICC and defined Bland–Altman plots) for interobserver and inter-technique agreement in estimating basal diameters when using pseudocolor composite and red laser images by comparing them with 20 MHz US results. Conclusions: UWF fundus imaging, when complete visualization of the tumor margins is possible, could be as reliable as ultrasonography in the measurement of the basal diameters of choroidal melanocytic tumors.

In this study, we aimed to identify the features of indeterminate choroidal melanocytic lesions visualized on optical coherence tomography angiography (OCTA) and to identify the predictors of growth. We retrospectively evaluated 86 patients with indeterminate lesions treated at our centre from 2016 to 2021. Clinical management involved active surveillance followed by brachytherapy if growth was detected. The lesions were classified into two groups according to whether they grew (small melanomas) or remained stable (choroidal nevi). Growth was detected in 19 (22.1%) lesions. All patients underwent OCTA at baseline. These images were compared to identify the possible predictors of growth. Significant between-group differences were observed in thickness (p = 0.00), greatest basal diameter (p = 0.00), number of risk factors (p = 0.00), symptoms (p = 0.001; relative risk [RR]: 4.3), orange pigment (p = 0.00; RR: 6.02), and ultrasonographic hollowness (Kappa sign); p = 0.000; RR: 5.3). The melanomas had significantly more vessels with a diameter ≥ 76.3 µm (p = 0.02; RR: 2.46). The time to growth in these lesions was significantly shorter (p = 0.05) than in lesions with smaller vessels. These findings show that vessel diameter quantified by OCTA can help differentiate between choroidal nevi and small melanomas, when considered together with clinical risk factors.

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