Purpose: To investigate the treatment outcomes and predictive factors affecting treatment success of half-fluence photodynamic therapy (hf-PDT) in pachychoroid-associated neovascularization (PNV).
Methods: Twenty-four eyes of 23 PNV patients who underwent hf-PDT were included in this study. The results of optical coherence tomography (OCT) and OCT-angiography imaging were analyzed. The total choroidal area (CA), luminal area (LA), and stromal area (SA) were measured using ImageJ software. Baseline characteristics of the eyes showing complete response (group 1) and the eyes with partial response or unresponsive to hf-PDT (group 2) were compared.
Results: The mean age of the patients was 54.2±9.6 years. The mean follow-up time after hf-PDT was 20.7 ± 13.6 months. Three months after hf-PDT, the subretinal fluid had completely regressed in 18 eyes (75.0%), partial resolution was observed in 3 eyes (12.5%), and 3 eyes (12.5%) were unresponsive to hf-PDT. When the baseline characteristics before hf-PDT were evaluated between the groups, the mean central choroidal thickness (411.5 ± 115.1 µm vs 284.8 ± 69.4 µm), the mean CA (1.082 ± 0.315 mm2 vs 0.795 ± 0.242 mm2) and the mean LA (0.795 ± 0.234 mm2 vs 0.578 ± 0.200 mm2) was significantly higher in group 1 compared to group 2 (p = 0.019, p = 0.018, p = 0.018, respectively).
Conclusion: Hf-PDT is an effective treatment method usually providing total resolution of subretinal fluid in PNV cases. A high baseline central choroidal thickness and large luminal area may be positive predictive factors in terms of full anatomical response to hf-PDT. It may be possible to plan a more effective treatment strategy by keeping these factors in mind.
Keywords: Half-fluence photodynamic therapy; optical coherence tomography; pachychoroid-associated neovascularization.