Predicting the therapeutic effect of photodynamic therapy on circumscribed choroidal haemangioma: a retrospective cohort study

Background/aims Circumscribed choroidal haemangioma (CCH) can cause visual impairment, primarily managed with photodynamic therapy (PDT). This study aimed to identify predictive factors of therapeutic response in patients with CCH treated with PDT and to analyse serial anatomical outcomes, focusing on visual acuity, tumour characteristics, and inner retinal microstructures. Methods This retrospective study included patients diagnosed with CCH at Severance Eye Hospital, Yonsei University, from January 2005 to December 2022. We reviewed patient records and multimodal imaging, assessing demographics, including post-PDT visual acuity changes, age, laterality and sex, and multimodal imaging features such as tumour location and height, presence of subfoveal subretinal fluid (SRF), enhanced reflectivity of the retinal pigment epithelium and external limiting membrane (ELM) disruption. Results Among 114 patients with CCH (82 men, 65.6%; mean age 52.1±14.0 years), 45 (39.5%) had asymptomatic CCH, while 69 (60.5%) presented with symptomatic CCH. PDT was administered to 41 symptomatic patients (59.4%). The pretreatment LogMAR visual acuity was 0.50±0.63, which remained stable 1 year after PDT (0.53±0.64, p=0.666). However, it worsened 3 years after PDT (0.81±0.89, p=0.024), around the time tumour regrowth was observed. At 1-year post-PDT, tumour volume and height decreased by an average of 34.6% and 32.4%, respectively, accompanied by a 75.0% reduction in SRF. Patients with >75% vol reduction showed greater SRF persistence, while a higher initial SRF height was associated with complete SRF absorption following PDT. ELM disruption was identified as a significant predictor of poorer visual acuity, reduced tumour volume response and limited SRF absorption. Conclusions The presence of SRF predicts favourable tumour size reduction and SRF absorption post-PDT, while ELM disruption serves as an important prognostic factor for visual acuity and structural outcomes, aiding in pre-PDT treatment planning.