The aim of this study was to evaluate the choroidal thickness (CT) changes associated with visual function following photodynamic therapy (PDT) for a diffuse choroidal hemangioma in Sturge–Weber syndrome. We report a case of Sturge–Weber syndrome and symptomatic serous retinal detachment (SRD) with diffuse choroidal hemangioma treated with PDT. Visual acuity (VA), macular sensitivity measured by means of MP1 microperimeter (Nidek Technologies, Padova, Italy), retinal and CT, measured by means of enhanced depth optical coherence tomography (EDI–OCT, Spectralis, Heidelberg Engineering, Heidelberg, Germany) were analyzed at baseline, 3 and 12 months follow-up.After the PDT VA and macular sensitivity improved.The OCT examination showed the resolution of SRD. The choroid was measured after PDT using EDI–OCT. At baseline, the subfoveal CT showed a progressive thickness reduction from 251 to 83 lm during follow-up. To our knowledge, this is the first report of CT changes after PDT for a diffuse choroidal hemangioma in Sturge–Weber syndrome in a longterm follow-up. The CT measurement represents a potential parameter to better follow choroidal hemangiomas and their response to treatment. However,the long-term choroidal changes should be carefully taken into account.