Suspicious choroidal naevi: when to observe, when to treat

Summary To find and characterize all existing choroidal naevi, a systematic fundus examination with the indirect ophthalmoscope and the slit lamp using a non‐contact or contact lens for detail are mandatory. These are ideally supplemented with optical coherence tomography (subretinal fluid, thickness and internal structure of lesions <1 mm thick), fundus autofluorescence (recent and chronic subretinal fluid, orange pigment), and ultrasonography (thickness and acoustic profile of lesions >1 mm thick). Despite such imaging, the challenge lies in telling a small melanoma from a naevus. The mnemonic ‘To Find Small Ocular Melanomas’ reminds us to look for tumour Tickness more than 2 mm, subretinal Fluid, visual Symptoms, Orange pigment and tumour Margin touching the optic disc. Each of these features roughly doubles the likelihood of growth and, hence, malignancy. None of them are specific though – about 8% of benign naevi have orange pigment and subretinal fluid, and naevi can grow slowly, especially in patients <45 years of age, whereas the smallest melanomas show none of these 5 features. Surveillance for growth, a biopsy, or both may thus be needed for a treatment decision. This talk will introduce these principles with examples.