Ranibizumab plus verteporfin photodynamic therapy (PDT) remains effective in improving the visual outcomes in patients with polypoidal choroidal vasculopathy (PCV).1,2 By occluding polypoidal lesions and resolving exudative manifestations, PDT is considered to be an essential component of PCV treatment.3,4 However, PDT is not without risks – especially due to its the potential side effects to the retinal pigment epithelium (RPE).3,4 In view of this, the long-term visual outcomes of patients treated with half-dose PDT (hd-PDT) and standard-dose PDT (sd-PDT), both in combination with ranibizumab, were investigated by the research team led by Dr. Ian Y. Wong from the University of Hong Kong (HKU) and Dr. Xuan Shi from Peking University People’s Hospital, Beijing.2 The findings were published in Retina.2
The research team has previously shown that hd-PDT, combined with intravitreal ranibizumab, was able to induce high polyp regression rate in PCV cases that had one single polyp.5 However, the previous study had a relatively small sample size, and lacked the comparison with sd-PDT.5 The present study is the first to compare the visual outcomes between hd-PDT and sd-PDT in the treatment of PCV.2
“In recent years, interests have grown around optimizing the dosing and fluence regimen when performing PDT, so as to minimize the risks while still obtaining promising results,” the researchers wrote. “Whether hd-PDT can achieve equivalent results as sd-PDT in the treatment of PCV is unknown. This formed the basis for this study.”2
Fifty-eight treatment-naïve PCV patients were recruited in this prospective, consecutive, open-label comparative study, i.e. 26 and 32 subjects in the hd-PDT and sd-PDT arms, respectively.2 Baseline characteristics and ocular features were similar between the two study arms (p-value for mean best-corrected visual acuity [BCVA]=0.348; p-value for central retina thickness (CRT)=0.355).2
Regardless of the treatment arm allocation, patients also received intravitreal injections of ranibizumab 0.5mg/0.05ml.2 If disease activity was seen on optical coherence tomography (OCT) (reassessed every month), ranibizumab injections would be repeated.2
Within 7 days of the initial ranibizumab injection, PDT was given using 3mg/m2 verteporfin in the hd-PDT arm, instead of the standard 6mg/m2 verteporfin used in the sd-PDT arm.2 For both groups, standard fluence of 50J/cm2 over 83 seconds was used.2 Of note, the study protocol also included assessments via fluorescein angiography (FA) and indocyanine green angiography (ICGA) that were repeated every 3 months.2 Retreatment (with only ranibizumab or PDT plus ranibizumab) was given based on FA/OCT disease activity and the presence of polyps or branching vascular networks (BVNs).2
At month 12, there was no significant difference between the hd-PDT and sd-PDT arms in BCVA improvement and CRT reduction.2 After 1 single PDT session, polyp regression was achieved in 73.1% and 87.5% in the hd-PDT and sd-PDT arms, respectively (p=0.162).2 Nevertheless, 100% polyp regression was achieved in both study arms with repeated PDT sessions, without a statistically significant difference in the mean number of PDT sessions required.2 No adverse events or complications from treatment were reported in all subjects.2
“This suggested that hd-PDT could attain comparable polyp regression rate as sd-PDT, although with 1 single session the chance of inducing complete regression was apparently lower with hd-PDT, the difference was small,” the researchers wrote.2
The study also found that hd-PDT was able to produce superior results, as compared to sd-PDT, in those with baseline BCVA ≥20/50 (logMAR 0.4) (p=0.024) or when there were ≤3 polyps on ICGA (p<0.001).2
Acknowledging that future studies with larger sample sizes are required to confirm the study findings and eliminate a possible bias in baseline disease characteristics, the authors concluded that this study “highlighted the importance of customizing treatment strategy according to the baseline BCVA and ICGA features.”2
1. Koh A, Lai TYY, Takahashi K, et al. Efficacy and Safety of Ranibizumab With or Without Verteporfin Photodynamic Therapy for Polypoidal Choroidal Vasculopathy: A Randomized Clinical Trial. JAMA Ophthalmol. 2017;135(11):1206-1213.
2. Wong IY, Shi X, Gangwani R, et al. ONE-YEAR RESULTS OF HALF- VERSUS STANDARD-DOSE PHOTODYNAMIC THERAPY COMBINED WITH RANIBIZUMAB FOR POLYPOIDAL CHOROIDAL VASCULOPATHY. Retina. 2018;38(4):725-730.
3. Lee WK, Lee PY, Lee SK. Photodynamic therapy for polypoidal choroidal vasculopathy: vaso-occlusive effect on the branching vascular network and origin of recurrence. Jpn J Ophthalmol. 2008;52(2):108-115.
4. Ho M, Woo DC, Chan VC, et al. Treatment of polypoidal choroidal vasculopathy by photodynamic therapy, aflibercept and dexamethasone triple therapy. Sci Rep. 2016;6:36870.
5. Wong IY, Shi X, Gangwani R, et al. 1-year results of combined half-dose photodynamic therapy and ranibizumab for polypoidal choroidal vasculopathy. BMC Ophthalmol. 2015;15:66.