Intravitreal ranibizumab therapy versus photodynamic therapy for idiopathic choroidal neovascularization: a comparative study on visual acuity, retinal and choroidal thickness
Authors: Shi Xuehui , Wei Wenbin , Zhang Cong 
Published: January 2024

Background
Photodynamic therapy (PDT) has been recommended as a main treatment for idiopathic choroidal neovascularization (I-CNV). But the visual results of PDT were inconsistent and variable, and PDT may bring severe damage to the retinal pigment epithelium and choriocapillaries. In recent years, intravitreal ranibizumab therapy, showing favorable visual outcomes, has developed as an advanced treatment for choroidal neovascularization (CNV). Although both methods have been reported to be effective in treating I-CNV, there is no detailed comparative report between the two methods. This study aimed to compare visual outcomes, retinal and choroidal thickness between intravitreal ranibizumab therapy and PDT in the treatment of I-CNV, and investigate the correlation of visual outcomes with retinal and choroidal thickness in each of the two groups.

Methods
Thirty-seven eyes of 37 patients with I-CNV were involved in this study; 19 eyes were treated with intravitreal ranibizumab therapy and 18 eyes were treated with PDT. The best corrected visual acuity (BCVA) was recorded before and at each follow-up visit after treatments (logMAR). Enhanced-depth imaging optical coherence tomography (EDI-OCT) was used to evaluate the retinal structural changes, and to measure central retinal thickness (CRT) and central choroidal thickness (CCT).

Results
Mean BCVA was 0.64±0.27 in PDT group and 0.69±0.22 in ranibizumab group at baseline (P=0.55). When compared with the baseline, mean BCVA in PDT group was improved significantly at 3-month after PDT (0.41±0.16, P=0.002), then changed little (0.42±0.25 at 12-month, P=0.88). Whereas mean BCVA in Ranibizumab group was improved significantly at each follow-up visit. It improved much more obviously in the first month and then remained stable. The mean BCVA in the ranibizumab group was significantly better at each follow-up visit than that in PDT (P <0.05). When compared with the baseline, mean CRT in PDT group decreased significantly since 3-month visit, whereas mean CRT in ranibizumab group decreased significantly from 1-month visit. Mean CRT at 1-month and 3-month decreased much more in ranibizumab group than that in PDT group, almost in the same period as BCVA improving. When compared with the baseline, mean CCT did not change significantly at each follow-up visit in each group (P >0.05). The CCT difference was not statistically significant between the two groups at each same time visit (P >0.05). Mean BCVA was correlated with CRT, but was not correlated with CCT.

Conclusions
Both intravitreal ranibizumab therapy and PDT are effective for the treatment of I-CNV. It is obvious that ranibizumab therapy is significantly superior to PDT in improving BCVA and decreasing CRT. CRT decreases much more rapidly in ranibizumab group than in PDT group, simultaneously with visual improvement. CRT reduction has significant correlation with the visual outcomes in the recovery of I-CNV, whereas BCVA prognosis may have no correlation with CCT. CCT is not changed significantly after each of the treatments. Both PDT and ranibizumab therapy may have no significant effect on choroid.