Long term outer retinal changes in central serous chorioretinopathy submitted to half-dose photodynamic therapy.

Purpose: To evaluate long-term changes in the foveal and parafoveal outer retina after half-dose photodynamic therapy (HD-PDT) in central serous chorioretinopathy (CSC).

Methods: Retrospective study including CSC patients submitted to HD-PDT. Best corrected visual acuity (BCVA) was evaluated. Spectral-domain optical coherence tomography automatic segmentation algorithm was used and data on retinal, inner retinal, outer retinal and outer nuclear layers (ONL) in both foveal 1 mm (C) and parafoveal 3 mm ETDRS circles for the superior, nasal, inferior and temporal sectors, were obtained at baseline and 3, 12 and 24 months post-treatment. Subfoveal choroidal thickness, photoreceptors' outer segment thickness, subretinal fluid (SRF) height and width were also measured.

Results: Twenty-one eyes of 15 patients were included. At baseline, the mean ONL thickness in the foveal area was significantly thinner in affected eyes compared to their fellow unaffected ones (55,50 ± 32,75 μm vs 93,00 ± 17,0 μm; p = 0,011), and was negatively correlated to logMAR BCVA (R=-0,601, p = 0,008) ONL thickness increased by 10,94 ± 11,88 μm at 24 months in the foveal area, and all the parafoveal sectors presented a similar increase. Baseline SRF width was significantly correlated with baseline BCVA (R1 = 0,483, p = 0,036), and with ONL thickness in all sectors.

Conclusion: In our study we found a significant long-term increase in foveal and parafoveal ONL thickness in CSC after HD-PDT, suggesting that this seems to be a safe treatment for the outer retina. This is the first study mapping the outer retinal changes in the macular area to 24 months follow up.