Purpose: To investigate the longitudinal changes in choroidal thickness of the eyes of diabetic retinopathy patients during 12 weeks after panretinal photocoagulation (PRP).
Methods: This prospective, comparative study included 46 eyes undergoing four-session PRP. At baseline and 1, 4, 8, and 12 weeks after completion of the PRP treatments, subfoveal choroidal thickness (SFCT) was measured by using enhanced depth imaging optical coherence tomography. Also measured were central macular thickness (CMT) and best-corrected visual acuity (BCVA).
Results: The mean SFCT at baseline was 309 ± 77 μm, changing to 323 ± 78 μm, 315 ± 75 μm, 299 ± 68 μm, and 289 ± 71 μm at 1, 4, 8, and 12 weeks, respectively. This constituted a statistically significant increase at 1 week and a significant decrease at 12 weeks. The mean baseline CMT was 294 ± 92 μm, which increased significantly 1 week after PRP to 344 ± 123 μm, remaining higher at 4 weeks (340 ± 117 μm) and 8 weeks (318 ± 100 μm), but subsiding to baseline at 12 weeks (311 ± 96 μm). The mean BCVA at baseline and the last visit were 0.63 ± 0.28 logMAR and 0.53 ± 0.42 logMAR, respectively. There was no significant difference in BCVA between eyes with and without central-involved diabetic macular edema at all time points. Compared with the baseline, the mean BCVA dropped at 1 week and 4 weeks but recovered by 12 weeks.
Conclusions: Choroidal thickness decreased 12 weeks after PRP, suggesting that PRP may reduce choroidal vascular permeability or cause atrophy of choroidal vessels over a 12-week period.