Factors influencing the outcome of polypoidal choroidal vasculopathy following combined treatment with photodynamic therapy and intravitreal ranibizumab

Sir,

We read with interest the article by Ho et al¹ describing the factors influencing the treatment outcomes for polypoidal choroidal vasculopathy (PCV) following combination photodynamic therapy and intravitreal ranibizumab injections. This study highlights the key role of indocyanine green angiography (ICGA) in the diagnosis and management of PCV.^{2, 3, 4}

In addition to the clinical and angiographic features described, it is also important to consider insights from studies that classified PCV into various subtypes. It has been suggested that PCV may not be a single disease entity, but may consist of different subtypes that influence the long-term prognosis. In a study of 107 consecutive patients with PCV, three subtypes of PCV were identified on the basis of the features seen on ICGA and fluorescein angiography.² The PCV subtype significantly affected the visual outcome at 5 years. In our series, 21.5% of patients experienced ≥0.3 LogMAR unit decrease in visual acuity at 1 year. However, the rates of visual loss differed significantly among the three subtypes: 0% for type A PCV, 8.7% for type B, and 35.3% for type C (P=0.001).² A similar pattern was observed over the subsequent 5 years.

In the first paragraph of the discussion, the authors reported ‘81% rate in polyp eradication at 1 year'.¹ However, this term is also used in the abstract, where it is stated that ‘20.2% (15/74) cases achieved polyp eradication on angiogram', whereas 60.8% ‘achieved polyp size reduction'.¹ Thus, the statement in the discussion may be misleading to some readers, who may infer ‘eradication' to mean total closure of the polyps, which actually occurred in only 20.2% of cases. We are curious to know how the authors determined a decrease in size of the polyps. Was this based on the total area of all polyps and, if so, what was the minimum decrease in area required? Polyp closure is an important consideration in the management of PCV because some patients may suffer massive hemorrhages, with severe loss of vision.⁵

In summary, we congratulate the authors on describing the risk factors for PCV outcomes, which highlights the need to consider various categories and subtypes of this disease.

CST receives travel support from Bayer, Heidelberg Engineering, and Novartis. He also receives research support from the National Healthcare Group Clinician Scientist Career Scheme Grant (CSCS/12005). THL receives travel support from Novartis and Heidelberg Engineering. The remaining authors declare no conflict of interest.