A total of 87 patients with chronic or recurrent CSC were included. Twenty-seven patients were excluded because: their follow-up was less than 12 months (25 patients), the diagnosis was changed to PCV (1 patient) or their follow-up OCT data were missing (1 patient). Finally, data from 60 patients (66 eyes) were analyzed. From this, 41 patients (46 eyes) had received half-dose PDT and 19 patients (20 eyes) had received one-third-dose PDT (Figure 1).
The baseline demographic data and clinical characteristics of the patients in the two treatment groups are summarized in Table 1. There were no statistically significant differences in gender, laterality, body mass index, duration of symptoms, type of CSC, leakage type on FA, spot size of PDT, initial BCVA or CRT. However, the half-dose PDT group was older than the one-third-dose PDT group (P=0.03).
Changes in BCVA
The half-dose PDT group showed statistically significant BCVA improvement at 1, 3, 6 and 12 months after PDT treatment when compared with the baseline (Table 2). In the one-third-dose PDT group, BCVA showed statistically significant improvement at 6 and 12 months after PDT treatment, when compared with the baseline.
When the two groups were compared, the half-dose PDT group did not show a statistically significant difference in BCVA (Table 2), or in BCVA improvement (Table 3) at 1, 3, 6 and 12 months; relative to the one-third-dose PDT group.
Changes in CRT
Both groups showed statistically significant reductions in CRT, compared with the baseline, at 1, 3, 6 and 12 months after PDT treatment (Table 4). In contrast, the half-dose PDT group did not show statistically significantly differences in CRT or CRT reduction at 1, 3, 6 and 12 months, compared with the one-third-dose PDT group at these times (Tables 4 and 5).
The accumulated number of eyes with complete SRF reabsorption after a single PDT treatment
In both groups, all eyes had evidence of SRF reabsorption within 12 months after a single PDT treatment (Table 6).
The cumulative number of eyes with recurrence of SRF after a single PDT treatment
In the half-dose PDT group, the accumulated numbers of eyes with recurrence of SRF after achieving a dry macula were 2 (4.3%), 4(8.7%) and 7(15.2%) within 3, 6 and 12 months after a single PDT treatment (Table 7). Two eyes had recurrent SRF within 3 months and were successfully treated with a repeated half-dose PDT. Two eyes had recurrence within 6 months; one was successfully treated with focal laser, while the other spontaneously resolved with observation.
In the one-third-dose PDT group, the cumulative numbers of eyes with recurrent SRF after a dry macula, were 1(5%), 5(25%) and 8(40%) within 3, 6 and 12 months after PDT treatment. One eye had a recurrence within 3 months and was successfully treated with a repeated one-third-dose PDT. Four eyes had SRF recurrence within 6 months. In 3 cases, these were successfully treated with a repeated one-third-dose PDT. The other case spontaneously resolved after observation. In both groups, three eyes had recurrence of SRF at their 12-month follow up.
The one-third-dose PDT group showed a significantly, higher recurrence rate than that of the half-dose PDT group at 12 months (P = 0.027) (Table 7.)
The comparison of demographic data of the patients with recurrence of subretinal fluid, after photodynamic therapy, between the two treatment groups
The comparison of demographic data of the patients with recurrence of subretinal fluid after photodynamic therapy, between the two treatment groups is summarized in Table 8. There were no statistically significant differences in age, gender, laterality, body mass index, duration of symptoms, type of CSC, leakage type on FA, spot size of PDT, initial BCVA and initial CRT.
After recurrence SRF, with a single PDT, 6/7 eyes in the half-dose PDT groups and 7/8 eyes in the one-third-dose PDT group were reperformed FA. In the half-dose PDT group, the 5/6 eyes and 1/6 eyes consisted of leaks in area having been previously treated, and de-novo leakage, respectively. In the one-third-dose PDT group, the 6/7 eyes and 1/7 eyes consisted of leaks in area having been previously treated and de-novo leakage, respectively.