No systemic and ocular adverse events associated with verteporfin injection were observed throughout the study period. The baseline demographic and clinical data of the two treatment groups are summarised in Table 1. A total of 27 eyes from 27 patients with chronic CSC were considered, of which 15 eyes were treated with 1/3PDT and 12 eyes were treated with 1/2PDT. No significant differences were found in the sex (p=0.78), baseline BCVA (1/2PDT, 0.13±0.25, 1/3PDT, 0.21±0.25; p=0.35), duration of symptoms (1/3PDT, 18.4±16.4, 1/2PDT, 18.8±12.2 ; p=0.59), CRT at baseline (1/2PDT, 334.2±94.5; 1/3PDT, 275.1±94.5; p=0.06), choroidal thickness at baseline (1/2PDT, 451.2±132.5; 1/3PDT, 452.2±85.1; p=0.88), and PDT spot size (1/2PDT, 2888.3±550.5; 1/3PDT, 2558.9±710.7; p=0.22), except for age (1/2PDT, 51.5±5.7; 1/3PDT, 46.3±7.2; p=0.04) between the two treatment groups.
Table 1 Baseline demographic and clinical data of the 1/2PDT and 1/3PDT groups
BCVA: best-corrected visual acuity, IOP: intraocular pressure, OPP: ocular perfusion pressure, CFT: central foveal thickness, CCT: central choroidal thickness, 1/2PDT: half-dose photodynamic therapy, 1/3PDT: one-third dose photodynamic therapy, logMAR: logarithm of the minimum angle of resolution
The disappearance rate of SRF 1 month after treatment was 92% (11/12 eyes) in the 1/2PDT and 93% (14/15 eyes) in the 1/3PDT group.
Recurrence was observed in one eye at the 6-month follow-up in the 1/2PDT group and two eyes at the 3-month follow-up in the 1/3PDT group over the 6-month follow-up period.
No significant improvement was observed in the BCVA compared to baseline (0.13±0.25 and 0.21±0.25, respectively) at two weeks (0.13±0.21 and 0.19±0.25, respectively), 1 month (0.13±0.22 and 0.13±0.23, respectively), 3 months (0.07±0.19 and 0.12±0.27, respectively) and 6 months (0.02±0.19 and 0.13±0.30, respectively) after PDT in the 1/2PDT and 1/3PDT groups.
Figure 2 depicts the time course of the rate of change in the m-MBR against baseline in the 1/2PDT and 1/3 PDT groups. In the 1/2 PDT group, the average m-MBR against baseline (100%) significantly decreased to 85.3% (p=0.004), 85.0% (p=0.037), 83.1% (p=0.015) and -82.7% (p=0.015) 2 weeks and 1, 3 and 6 months after treatment, respectively. In the 1/3PDT group, the average m-MBR against baseline (100%) decreased to 87.2% (p<0.001), 98.5% (p=0.79), 100.2% (p=0.99), and 92.5% (p=0.14) 2 weeks and 1, 3 and 6 months after treatment, respectively. The rate of change in the m-MBR differed (statistically) significantly between the 1/2PDT and 1/3PDT groups at 2 weeks and 1 month and 3 months after treatment.
Foveal choroidal thickness
Figure 3 shows the time course of the rate of change in the CCT against baseline in the 1/2PDT and 1/3PDT groups. In the 1/2PDT group, the average of rate of change of CCT against baseline (100%) significantly decreased to 83.1% (p<0.001), 80.6% (p<0.001), 78.1% (p<0.001) and 79.6% (p<0.001) 2 weeks and 1, 3 and 6 months after treatment, respectively. In the 1/3PDT group, the average of the rate of change of CCT against baseline (100%) decreased to 90.3% (p=0.001), 92.2% (p=0.001), 90.7% (p=0.001), and 92.8% (p=0.5) 2 weeks and 1, 3 and 6 months after treatment, respectively. The rate of change in CCT differed (statistically) significantly between the 1/2PDT and 1/3PDT groups 2 weeks and 1, 3 and 6 months after treatment.
The ONH-MBR showed no significant fluctuation at 106% after 2 weeks, 104% after 1 month, 101% after 3 months, and 102% after 6 months in the 1/2PDT group. The ONH-MBR showed no significant fluctuation at 99% after 2 weeks, 96% after 1 month, 96% after 3 months, and 99% after 6 months in the 1/3PDT group.
Moreover, no significant change was observed at any time-point after treatment compared to baseline.
The OPP also showed no significant fluctuation at 98% for 2 weeks, 102% for 1 month, 103% for 3 months, and 110% at 6 months in the 1/2PDT group and at 97% for 2 weeks, 107% for 1 month, 102% for 3 months, and 104% for 6 months in the 1/3PDT group. There was no significant change in the fellow eyes at any time after treatment compared to baseline.