Crossover to 689 nm laser therapy after poor responsiveness to subthreshold micropulse laser for chronic central serous chorioretinopathy.

Purpose: To compare the visual and anatomical outcomes of 689 nm laser therapy (689-LT) and continued subthreshold micropulse laser (SML) therapy, for chronic central serous chorioretinopathy (cCSC) eyes after poor responsiveness to initial SML treatment.

Methods: The retrospective study included 32 cCSC patients, of which 15 patients received continued SML, and 17 patients received 689-LT. Best corrected visual acuity (BCVA), central retinal thickness (CRT), the maximum height of subretinal fluid (mSRF), subfoveal choroidal thickness (SFCT), three-dimensional choroidal vascularity index (CVI), and the vascular density of choriocapillaris (CCVD) of two groups were evaluated and compared at baseline, one-month and three-month follow-up after treatment.

Results: Thirty-two cCSC eyes of 32 patients (7 female, 25 male) were included in our study, with a mean age of 46.69 ± 6.56 years. Three months after treatment, complete resolution of SRF was achieved in four eyes in the 689-LT group, whereas no eyes displayed complete resolution in the SML group. There were no significant improvements in BCVA and CCVD at the three-month follow-up in both groups. In the 689-LT group, at one-month and three-month follow-ups, there was a significant reduction in CRT, mSRF, SFCT and CVI, compared to the baseline (p < 0.001 in all analyses). There were no statistically significant changes in CRT, mSRF, SFCT and CVI in the SML group (p > 0.05 in all analyses). The ANOVA test for repeated measures showed the changes in the measurements over time were significantly different between the two groups (P value using Greenhouse-Geisser test < 0.05).

Conclusion: 689 nm laser therapy provides the opportunity for cCSC eyes with poor responsiveness to SML treatment, especially when verteporfin is unavailable. There was also a notable recovery in the abnormal dilatation of choroidal vessels in the 689-LT group. Further studies are warranted to investigate the long-term efficacy and safety of 689 nm laser therapy in the management of cCSC.