Disadvantages of photodynamic therapy for polypoidal choroidal vasculopathy

Dear Editor, This case report is not about the diagnosis of idiopathic central serous chorioretinopathy (ICSC) at the time of presentation as that is really not the objective of our case report.[1,2] The report is about the optical coherence tomography (OCT) showing changes of acute ICSC before the development of expanding dot sign on fluorescein angiogram. As mentioned in the letter, the fluorescein angiogram in the right eye at presentation is suggestive of forme fruste of ICSC or chronic ICSC and, by no stretch of imagination, appears like a precursor to the development of acute ICSC.

Dear Editor, This case report is not about the diagnosis of idiopathic central serous chorioretinopathy (ICSC) at the time of presentation as that is really not the objective of our case report. [1,2] The report is about the optical coherence tomography (OCT) showing changes of acute ICSC before the development of expanding dot sign on fluorescein angiogram. As mentioned in the letter, the fluorescein angiogram in the right eye at presentation is suggestive of forme fruste of ICSC or chronic ICSC and, by no stretch of imagination, appears like a precursor to the development of acute ICSC.
Regarding the question of the inability of raster line scan to pick up all the pigment epithelium detachment (PEDs) seen on the map, we would like to mention the very basic fact that the raster line scan shows the morphological alterations seen at one particular line scan through which the slice navigator is passing. The changes that are seen on the 3D retinal pigment epithelium (RPE) map are mapping the entire area of the cube and thus all the changes seen on the map cannot be seen in a single line scan. [3] None of the other conditions mentioned in the letter, including ICSC, can be diagnosed based on OCT alone and thus this query has no relevance. [4] The OCT scan in this patient showed changes consistent with acute ICSC even before the development of expanding dot sign that is required to make the diagnosis of acute ICSC and thus it definitely scores over fluorescein angiography. Regarding the statement, "We wish to mention that OCT cannot predate any pathognomonic changes in CSCR," it would be interesting to see the reference to this statement.

Disadvantages of photodynamic therapy for polypoidal choroidal vasculopathy
Dear Editor, We read the article by Mitamura et al. [1] with interest. The article compares the short-term therapeutic effects of intravitreal bevacizumab (IVB) to those of photodynamic therapy (PDT) for polypoidal choroidal vasculopathy (PCV).
We would like to comment about the application of PDT in PCV. PDT is associated with several disadvantages. First, PCV often presents as multiple widely distributed lesions, so it might be difficult to treat all lesions, including multiple polyps and interconnecting vessels, with a single beam of PDT. Treatment of leaking polypoidal dilations only without treating the entire vascular complex can result in persistence or worsening of exudation. Second, it can be difficult to treat nodules in the peripapillary area with a round PDT beam. Third, features commonly associated with PCV such as a large PED or a large submacular hemorrhage are not usually amenable to PDT treatment. Fourth, PCV tends to recur repeatedly so multiple PDT treatments are often necessary, which can increase the risk of long-term choroidal atrophy. Cases of massive subretinal/ suprachoroidal hemorrhage have been reported soon after PDT. [2] Even 50% reduced light fluence PDT can produce a retinal pigment epithelial tear in pigment epithelial detachment. [3]

Authors' reply
Dear Editor, We appreciate the comments by Chhablani [1] regarding our article. [2] The best treatment for polypoidal choroidal vasculopathy (PCV) has still not been established. Our results suggest that photodynamic therapy (PDT) may be more effective than intravitreal bevacizumab (IVB) shortly after treatment for PCV. However, we did not evaluate the efficacy of intravitreal ranibizumab (IVR). Ranibizumab is a smaller molecule than bevacizumab, and the penetration of ranibizumab into the subretinal pigment epithelium space might be better than that of bevacizumab. As mentioned in our article, further studies to evaluate the efficacy of other anti-vascular endothelial growth factor (VEGF) agents and combination therapy of PDT and anti-VEGF agents are required and ongoing.
In reply to the first comment "it might be difficult to treat multiple widely distributed lesions with a single beam of PDT," we usually treat polyps in and around the macula with a single beam of PDT and other remote lesions are not treated or treated using direct photocoagulation. Tsujikawa et al. [3] reported that such remote lesions have only a minor effect on the visual outcome.
With respect to the second comment "it can be difficult to treat polyps in the peripapillary area with PDT," no eye had polyps around the disc in this study. Especially in Asians, the peripalliary PCV was reported to be rare as compared with macular PCV. [3] In reply to the third comment, we know that large submacular hemorrhage due to PCV cannot be treated with PDT. We usually treat PCV with large submacular hemorrhage using intravitreal gas injection followed by PDT or IVB, and such cases were not included in this study.
With respect to the fourth comment, we know that repeated PDT may lead to choroidal damage. However, it has been reported that PDT combined with IVR in an animal model did not adversely affect the recanalization of the choriocapillaris as compared with PDT alone, [4] suggesting that choroidal damage due to PDT may be reduced by combining with it. Ruamviboonsuk et al. [5] reported that there was no permanent nonperfusion affecting choriocapillaris after the combination therapy of PDT and IVR. Sato et al. [6] reported that the combination therapy of PDT and IVB may reduce the retreatment rate and the occurrence of subsequent submacular hemorrhage as compared with PDT monotherapy. As for other adverse events, retinal pigment epithelial tear can occur not only after PDT but also after IVB. [7] In reply to the comment "considering the economic burden associated with PDT," continuous monthly IVR is more expensive than PDT. Most recently, it has been reported that combination therapy of PDT and IVR for PCV showed encouraging results concerning visual acuity (VA), incidence of subretinal hemorrhage, and recurrence of polyps. [5] VA improvement 6 months after IVR was reported to be 7.2 letters, [8] but VA improvement after combination therapy of PDT and IVR was 11.6 letters. [5] Kokame et al. [8] described that visual outcomes of IVR monotherapy for PCV may be worse than those for exudative age-related macular degeneration. Taken together, we disagree with the comment "anti-VEGF drugs alone could be the preferred treatment for symptomatic PCV."