Subthreshold micropulse 520-nm laser for acute central serous chorioretinopathy: short-term outcomes and structural OCT biomarkers

Abstract Background Although acute central serous chorioretinopathy (CSC) frequently resolves spontaneously, prolonged subretinal fluid (SRF) may cause photoreceptor damage, and subthreshold micropulse laser (SML) has emerged as a safe, fovea-sparing intervention. We evaluated the short-term anatomical and functional outcomes of microsecond-pulsed 520 nm laser in consecutive eyes with acute CSC, with emphasis on structural optical coherence tomography (OCT) biomarkers and subfoveal choroidal thickness as potential predictors of treatment response. Methods This retrospective, consecutive, interventional case series included 14 eyes of 14 patients with acute CSC (symptom duration ≤ 12 weeks) treated with subthreshold microsecond-pulsed 520 nm laser at a single referral center. Central subfield thickness (CST) and best-corrected visual acuity (BCVA) were assessed at baseline and 30 days. Baseline OCT biomarkers, including external limiting membrane (ELM) and ellipsoid zone (EZ) integrity, photoreceptor outer segment (PROS) elongation, and subfoveal choroidal thickness, were recorded. Pre- and post-treatment comparisons used the Wilcoxon signed-rank test; associations between baseline biomarkers and complete SRF resolution were explored using the Fisher exact and Mann–Whitney U tests. Results Fourteen eyes of 14 patients (71.4% male; mean age 47.6 ± 9.1 years) were included. Mean CST decreased from 374.6 ± 90.6 μm to 263.4 ± 56.9 μm (mean reduction 111.3 μm; 95% CI, 57.3–165.3 μm; p = 0.001), and mean logMAR BCVA improved from 0.17 ± 0.11 to 0.10 ± 0.12 ( p = 0.011). Complete SRF resolution occurred in 6 eyes (42.9%) and partial resolution in 4 eyes (28.6%); no eye worsened. PROS elongation was significantly associated with failure to achieve complete resolution (Fisher exact p = 0.015); shorter symptom duration and better baseline BCVA were also associated with complete resolution ( p = 0.026 and p = 0.032), and higher baseline CST correlated with greater relative CST reduction (ρ = 0.72, p = 0.004). No recurrence was observed among the 7 eyes followed to 6 months, with no adverse events. Conclusions In this uncontrolled series, subthreshold microsecond-pulsed 520 nm laser treatment was associated with significant short-term anatomical and functional improvement in acute CSC. Because acute CSC has a high rate of spontaneous resolution and no untreated control group was available, these preliminary, hypothesis-generating findings cannot be attributed with certainty to the treatment. In exploratory analyses, PROS elongation and EZ disruption were associated with incomplete short-term SRF resolution; these candidate biomarkers require validation in larger prospective controlled studies. Trial registration Not applicable; this was a retrospective observational study (retrospectively registered).