Clinical Features and Multimodal Imaging Findings of Focal Scleral Nodule: Potential Association between Lesion Characteristics and Age

Abstract

To describe the clinical course and anatomic features of focal scleral nodules (FSNs) based on their clinical characteristics and multimodal imaging findings and analyze their potential associations with the patient's age. Single-center, retrospective, observational case series. Twenty-three lesions of 23 patients with FSN. Clinical characteristics were analyzed, and multimodal imaging was performed, including color fundus photography, OCT, fundus autofluorescence imaging, near-infrared imaging, B-scan ultrasonography, fluorescein and indocyanine green angiography, and OCT angiography of FSNs. Qualitative features, including the slope of anterior curvature (curvature of the dome shape is less than nodular curvature, which is less than volcanic curvature; i.e., volcanic curvature has the steepest slope), retinal pigment epithelium (RPE) status, and fluid compartments, were analyzed. Quantitative measurements, including maximum linear basal diameter, maximum horizontal length at the choroidoscleral border, maximum vertical length (Vmax) from the choroidoscleral border, and choroidal thickness, were analyzed. The mean age at presentation was 44 ± 17 years (range, 4-68 years), and the mean follow-up duration was 32.2 ± 29.5 months. On OCT, all lesions were confined to the sclera. Patients with volcanic or nodular anterior curvature were younger than those with the dome-shaped phenotype (35 ± 19 years vs. 52 ± 9 years, respectively; Mann-Whitney U test; P= 0.015). The Spearman rank correlation analysis displayed a significant correlation between age at diagnosis and Vmax (r=-0.466; P= 0.025). The Wilcoxon matched paired t test for the patients demonstrated a significant decrease in Vmax at the final follow-up visit (initial, 555 ± 228 μm vs. final, 517 ± 202 μm, respectively; P= 0.028). We observed subretinal fluid, intraretinal fluid, pigment epithelial detachment, and severe outer retinal atrophy in a relatively older population with sustained nodular or volcanic anterior curvature (age, 52 ± 7 years; range, 43-60 years). One lesion diagnosed in a patient aged 4 years demonstrated spontaneous regression. Young patients tended to have protruded lesions (high Vmax) with nodular or volcanic anterior curvature. Older patients manifested the dome-shaped phenotype, and those with sustained nodular or volcanic curvature tended to develop fluid compartments or atrophic changes of the overlying RPE and retina because of possible chronic mechanical compression. Thus, there could be a significant association between FSN phenotype and age.