Five participants were dismissed with an unidentifiable sclerochoroidal border in the OCT image at 1 week post PRP. Finally, the study consisted of 32 participants (19 women, 13 men) with a mean age of 59 ± 11 years (range, 38–72 years;
Table 1). A total of 46 eyes were included, comprising 13 eyes (from 11 patients) with center-involved DME (including two eyes with subretinal fluid, four eyes with cystoid macular edema, and seven eyes with just thickened retinas) and 33 eyes (from 26 patients) without center-involved DME. Patients received a mean ± standard deviation of 1340 ± 85 laser spots for PRP. There was no significant difference between eyes with or without center-involved DME in the number of laser spots, with a mean of 1346 ± 75 or 1336 ± 90 in eyes with or without center-involved DME, respectively (
P = 0.729). The individual data points for the measures of SFCT (
Fig. 1A), CMT (
Fig. 1B), and BCVA (
Fig. 1C) at all time points are shown in
Figure 1.
The mean SFCT of the 46 eyes at baseline was 309 ± 77 μm, increasing to 323 ± 78 μm at 1 week, 315 ± 75 μm at 4 weeks, 299 ± 68 μm at 8 weeks, and 289 ± 71 μm at 12 weeks after PRP (
Fig. 2A). ANOVA with the Bonferroni post hoc test showed that SFCT significantly increased from the baseline at 1 week (
P = 0.025), subsided to the baseline at 4 and 8 weeks (
P = 0.99 and
P = 0.149, respectively), and significantly decreased at 12 weeks (
P = 0.006).
The mean CMT of 46 eyes at baseline was 294 ± 82 μm and at 1, 4, 8, and 12 weeks post PRP was 344 ± 123 μm, 340 ± 117 μm, 318 ± 100 μm, and 311 ± 96 μm, respectively (
Fig. 2B). Repeated-measures ANOVA indicated a statistical difference between the mean CMT at baseline and the mean at all post-PRP times (
P < 0.001). The Bonferroni post hoc test revealed that CMT significantly increased from the baseline at 1 week (
P < 0.001) and 4 weeks (
P < 0.001), and remained higher at 8 weeks (
P = 0.041), but subsided to the baseline at 12 weeks (
P = 0.254).
The mean preoperative vision at baseline was 0.55 ± 0.38 logMAR, which worsened significantly to 0.62 ± 0.45 logMAR (
P = 0.018) at 1 week, to 0.63 ± 0.41 logMAR at 4 weeks (
P < 0.0001), and improved back to baseline at 8 weeks (0.58 ± 0.39 logMAR) and 12 weeks (0.52 ± 0.33 logMAR;
P = 0.23 and
P = 0.99, respectively;
Fig. 2C).
Eyes were divided into groups by the presence or absence of central-involved DME, and variables between the two groups were compared (
Table 2). For the eyes with central-involved DME, results of the Bonferroni post hoc test indicated that the SFCTs were similar to baseline at all time points after PRP (
P = 0.44,
P = 0.99,
P = 0.99, and
P = 0.68 at 1, 4, 8, and 12 weeks, respectively). For the eyes without central-involved DME, the difference from baseline was significant only at 12 weeks (
P = 0.037).
Regarding CMT, for the eyes with central-involved DME, results of the Bonferroni post hoc test indicated that there was a significant increase in CMT only at 1 week (P = 0.041), which subsided to baseline at 4 weeks. For the eyes without central-involved DME, the increase in CMT was significant at each time point (P < 0.001, P = 0.001, P = 0.001, and P = 0.003).
Concerning BCVA, the Bonferroni post hoc test revealed that in eyes with DME involving the center of the macula, BCVA worsened significantly from baseline at 4 weeks (P < 0.001) and at 8 weeks (P = 0.032), but returned to the baseline at 12 weeks (P = 0.99). In eyes without central-involved DME, the BCVA worsened significantly from baseline at 4 weeks (P = 0.042) but returned to the baseline at 8 weeks (P = 0.99) and 12 weeks (P = 0.717).
The correlation test revealed that there was no statistically significant correlation between the CMT at baseline and the change in SFCT at all time points after PRP (Pearson analysis, P > 0.05). Also, no significant correlation was found between the number of spots performed and the change in SFCT, CMT (Pearson analysis, P > 0.05), and BCVA (Spearman analysis, P > 0.05) at all post-PRP times. In addition, the correlations between SFCT/CMT and BCVA were not statistically significant at baseline and at all time points after PRP (Pearson analysis, P > 0.05), and similar findings were obtained between SFCT and CMT (Pearson analysis, P > 0.05). Also, no statistically significant correlation was found between the change in SFCT/CMT and the change in BCVA, or between the change in SFCT and the change in CMT, at all time points after PRP (Pearson or Spearman analysis, P > 0.05, respectively). However, significant correlation was found between the BCVA at baseline and the change in BCVA at 1 week (Spearman analysis, r = 0.334 and P = 0.023) and 12 weeks (Spearman analysis, r = −0.448 and P = 0.002) after PRP. Moreover, multiple linear regression analysis revealed that the baseline CMT was significantly associated with the change in BCVA at 1 week (P < 0.001; regression coefficient B, 0.001; standardized coefficient β, 0.601), 4 weeks (P < 0.001; regression coefficient B, 0.001; standardized coefficient β, 0.511), and 8 weeks (P < 0.001; regression coefficient B, 0.001; standardized coefficient β, 0.692) after PRP, but other factors (including age, duration of diabetes mellitus, the number of laser spots, and baseline SFCT) showed no significant association with the change in BCVA after PRP at all time points (P > 0.05, respectively).