Subretinal fluid morphology in chronic central serous chorioretinopathy and its relationship to treatment: a retrospective analysis on PLACE trial data

PURPOSE: To explore subretinal fluid (SRF) morphology in chronic central serous chorioretinopathy (cCSC) after one session of either high‐density subthreshold micropulse laser (HSML) treatment or half‐dose photodynamic therapy (PDT). METHODS: We retrospectively obtained optical coherence tomography (OCT) scans from a subset of patients from a randomized controlled trial on treatment‐naïve eyes with cCSC allocated to either HSML treatment or half‐dose PDT. OCT scans were evaluated prior to treatment and 6–8 weeks post‐treatment, where we measured maximum SRF height and width, calculated the maximum height‐to‐maximum width‐ratio (maxHWR) and calculated the total SRF volume. RESULTS: Forty‐one eyes of 39 cCSC patients were included. SRF morphology ranged from flat to dome‐shaped, quantified as maxHWR ranging between 0.02 and 0.12. SRF volume was median 0.373 μl (range: 0.010–4.425 μl) and did not correlate to maxHWR (rho = −0.004, p = 0.982). Half‐dose PDT was superior to HSML treatment in complete SRF resolution (RR = 3.28, p = 0.003) and in morphological changes of SRF (Δ(maximum height), p = 0.001; Δ(maximum width), p < 0.001; Δ(volume), p = 0.025). SRF resolved completely in 19/22 PDT‐treated eyes (86%) and 5/19 HSML‐treated eyes (26%). SRF volume increased in five eyes (26%) after HSML treatment, and in none of the eyes after half‐dose PDT. SRF morphology at baseline did not predict treatment outcomes. CONCLUSION: SRF morphology changed after both HSML treatment and half‐dose PDT in cCSC, with SRF disappearing in most PDT‐treated patients, whereas SRF volume increased in a sizeable proportion of HSML‐treated patients. Baseline SRF characteristics measured in this study were unable to predict outcomes after either HSML treatment or half‐dose PDT.