Obtaining the maximum treatment effect with minimal toxicity is a guiding principle of dosing in pharmacology and medicine. In managing patients with central serous chorioretinopathy (CSC), clinicians have traditionally chosen between two options: observation and thermal laser therapy. The fact that laser damages the retinal pigment epithelium (RPE) in the setting of a disease with a known risk of developing choroidal neovascularisation (CNV) has left clinicians seeking new treatments that are both more effective and less toxic.

Recently, various groups have reported that photodynamic therapy (PDT) can be an effective treatment for the serous exudation of CSC.^1–4 This approach is based on the notion that choroidal hyperpermeability, as demonstrated by indocyanine green angiography, is an underlying contributor to subretinal and sub-RPE fluid accumulations in CSC. The presumed therapeutic mechanism of action of PDT in these cases is closure of vascular channels in the choriocapillaris.¹ An undesired effect of verteporfin PDT in CSC, however, can be pigmentary RPE changes in the treatment zone and persistent hypoperfusion of the choriocapillaris as identified with ICG angiography.⁴

In this issue of BJO (p 869), Lai and co-workers describe a new strategy for …