Choroidal naevi are largely benign, but it is difficult to know whether a naevus has transformed to melanoma, and a small melanoma is indistinguishable from a naevus because it has not yet disturbed the overlying retinal pigment epithelium.

Choroidal naevi are found in about 6% of individuals in the UK, whereas only six people per million each year develop melanoma, says Professor Bertil Damato HonFCOptom, Honorary Consultant Ophthalmologist at Oxford Eye Hospital, and Consultant Ocular Oncologist at Moorfields Eye Hospital and St Erik Eye Hospital in Stockholm.

Improvements in ocular imaging and fundoscopy have resulted in too many patients with choroidal naevi undergoing unnecessary referral to hospital eye clinics. “This is causing severe problems, diverting limited resources from patients in greater need of urgent attention, such as those with melanoma, who may end up on longer waiting lists,” he says.