Green subthreshold laser for chronic central serous chorioretinopathy: A new therapeutic approach

Purpose: To evaluate the safety and efficacy of green subthreshold laser therapy using Norlase µSec Technology in patients with chronic central serous chorioretinopathy (CSCR) compared with observational management. Methods: This prospective comparative pilot study included 24 eyes from 24 patients with chronic CSCR, defined as persistence of subretinal fluid (SRF) for longer than 3 months confirmed by optical coherence tomography (OCT), fluorescein angiography (FA), and indocyanine green angiography (ICGA). Twelve eyes underwent subthreshold green laser treatment using the Norlase ECHO system (520 nm wavelength, 5% duty cycle, 200 ms exposure duration, 100 μm spot size), while 12 matched patients managed with observation alone served as controls. Laser treatment was delivered using grid, circular, or arc patterns targeting leakage areas identified on FA and ICGA. The primary outcome was the change in central foveal thickness (CFT) at 3 months. Secondary outcomes included SRF resolution, best-corrected visual acuity (BCVA), subfoveal choroidal thickness (SFCT), and adverse events. Results: Baseline demographic and clinical characteristics were comparable between groups (all p > 0.05). In the treatment group, mean CFT significantly decreased from 345 ± 18 μm at baseline to 244 ± 12 μm at 3 months (p = 0.001), whereas the control group showed no significant reduction (338 ± 21 μm to 319 ± 26 μm; p = 0.18). Complete SRF resolution was observed in 10/12 treated eyes (83.3%) compared with 3/12 control eyes (25%) (p = 0.01). Mean BCVA significantly improved in treated patients from 0.21 ± 0.09 logMAR to 0.12 ± 0.07 logMAR (p = 0.01), while no significant functional change was observed in controls (p = 0.31). Mean SFCT showed a mild reduction in the treatment group from 273 ± 11 μm to 261 ± 10 μm (p = 0.04). Between-group analysis demonstrated significantly greater anatomical and functional improvement in treated eyes. No treatment-related adverse events were reported. Conclusions: Green subthreshold laser therapy using Norlase µSec Technology was associated with significant anatomical and functional improvement in chronic CSCR compared with observational management at short-term follow-up. The treatment demonstrated a favorable safety profile and may represent a useful therapeutic option for chronic CSCR, although larger studies with longer follow-up are needed to confirm these findings. Trial registration: ClinicalTrials.gov Identifier: NCT07020793