Iris freckle: a distinct entity.

Purpose: To report distinctive clinical and imaging features of iris freckles to differentiate them from iris nevi.

Design: Retrospective observational study.

Subjects: 53 patients (277 freckles) with incidental iris freckles and 102 patients (104 nevi) with iris nevi that are either clinically stable or pathologically confirmed.

Methods: Patient data were collected from the Department of Ophthalmic Oncology, Cleveland Clinic, Cole Eye Institute database (2012-2023). Lesion characteristics were recorded from slit-lamp examination descriptions and review of colour photographs. Ancillary imaging features observed using anterior segment optical coherence tomography (AS-OCT) and ultrasound biomicroscopy (UBM) were assessed in patients (where available).

Main outcome measures: Comparison of clinical and imaging features of iris freckles and iris nevi.

Results: A total of 277 iris freckles and 104 iris nevi were analysed. Iris freckles were more frequently bilateral (17%; nevi 0%) and multiple (69%; nevi 2%) and located centrally (89%; nevi 17%) compared with iris nevi (p<0.001). The median freckle largest basal diameter and thickness were 0.8 mm (nevi; 2.1 mm, p<0.001) and 0.04 mm (nevi 1.0 mm, p<0.001), respectively. All iris freckles had irregular margins without any secondary effects compared with iris nevi. Iris freckles appeared flat without effacement of iris folds compared with iris nevi on AS-OCT (p<0.001). Iris freckles were not detectable by UBM. Heat map revealed that freckles demonstrated several features with uniform or near uniform values, whereas nevi demonstrated more variability in values across features.

Conclusions: Iris freckles exhibit specific clinical and imaging features reflective of their characteristic histological composition that support their classification as a distinct entity within the spectrum of iris pigmented lesions.