Prevalence of Iris Freckles (Iris Nevi)
Iris freckles (iris nevi) are common pigmented lesions affecting 5-8% of the general population, with prevalence increasing with age and occurring more frequently in white Americans. 1
Population-Specific Prevalence
The baseline prevalence of iris nevi is consistently reported at 5-8% in the general adult population, with significant demographic variations 1:
- White Americans demonstrate the highest prevalence rates compared to other ethnic groups 1
- Age-related increase: Prevalence rises progressively with advancing age across all populations 1
- Bilateral presentation occurs in approximately 17% of cases with iris freckles, though true iris nevi are rarely bilateral (0%) 2
Distinguishing Freckles from Nevi
Recent high-quality research establishes that iris freckles represent a distinct clinical entity separate from iris nevi 2:
- Iris freckles are characteristically multiple (69% of cases), bilateral (17%), centrally located (89%), with median diameter of 0.8 mm and thickness of 0.04 mm 2
- Iris nevi are typically solitary (98%), unilateral (100%), peripherally located (83%), with median diameter of 2.1 mm and thickness of 1.0 mm 2
- Iris freckles appear flat without effacement of iris folds on anterior segment OCT, whereas nevi demonstrate elevation and structural changes 2
Clinical Significance and Malignant Transformation Risk
While iris nevi are common, malignant transformation to melanoma occurs in 2.6% by 5 years and 4.1% by 10 years in patients with suspicious iris nevi 3:
- The ABCDEF risk stratification guide identifies high-risk features: Age <40 years (HR=3), Blood/hyphema (HR=9), Clock hour inferiorly (HR=9), Diffuse configuration (HR=14), Ectropion uveae (HR=4), Feathery margins (HR=3) 4, 3
- Diffuse growth pattern and hyphema represent the most powerful predictors of malignant transformation 4
- True iris freckles demonstrate uniform features without secondary effects and remain stable without intervention 2
Monitoring Recommendations
For suspicious iris nevi (not simple freckles), 21.6% demonstrate growth during mean follow-up of 10.6 years, compared to 76% of confirmed melanomas showing growth within mean 7.2 years 5:
- Periodic ophthalmologic surveillance is essential for any pigmented iris lesion with concerning features 5
- Lesions located in the inferior (86%) and temporal (66%) iris quadrants require heightened vigilance as these locations predominate in both suspicious nevi and melanomas 5
- Chamber angle involvement occurs more frequently in melanomas (40%) versus suspicious nevi (17%) 5