The Effect of Choriocapillary Response by Different Dosage of Verteporfin in Photodynamic Therapy

Central serous chorioretinopathy (CSC) usually affects middle-age male patients and is a well-characterized disorder leading to serous neurosensory elevation of the central macula. The acute form of the disease is associated with focal leakage at the level of the retinal pigment epithelium (RPE), and it is self-limited in the majority of patients, who also regain excellent vision. Occasionally, the neurosensory detachment persists and leads to pigment epithelial and photoreceptor damage with visual impairment. Chronic and persistent cases of CSC may yield further complications such as diffuse PRE decompensation, subretinal precipitates, descending atrophic tracts,dependent retinal detachments (RDs), cystoid macular edema, secondary choroidal neovascularization (CNV), and fibrous scarring. In this stage, patients may loose some vision permanently even resolve the subretinal fluid in the end. The limited efficacy of laser photocoagulation is because it targets only the RPE leak without specifically treating the underlying primary choroidal congestion and hyperpermeability. Photodynamic therapy (PDT) used liposomal benzoporphyrin derivative-monoacid, also known as verteporfin, currently as an option for the treatment of CNV that can minimize damage to surrounding viable retinal tissue. Recently, verteporfin PDT has been performed in the treatment of acute or chronic CSC and studies have demonstrated beneficial visual outcomes in the majority of patients. The mechanism of PDT in treating CSC is thought to be the result of choriocapillaris narrowing and choroidal hypoperfusion, leading to reduction of choroidal exudation and choroidal vascular remodelling. The use of PDT in the treatment of chronic CSC is not without complication, for example, RPE atrophy had been reported after PDT for chronic CSC. Moreover, with the use of mfERG, clinical and laboratory studies have demonstrated transient reduction in macular function following PDT. The potential retinal damage caused by PDT might be minimized by reducing the dose of verteporfin, while at the same time having sufficient photodynamic effects on the choroidal vasculature required for treating CSC. The half dose verteporfin in the treatment of either acute or chronic CSC had been demonstrated its efficacy and safety. The adequate dosage of verteporfin for PDT of CSC still remained as an open question. The previous study showed that even very low dosage of PDT could damage the choriocapillaris in animal study. Therefore, in treatment of this self-limited disease, the long-term safety will be a major concern. However, this long-term effect of low fluence PDT had not yet been evaluated. Therefore, we will perform this program to study the choriocapillary response and long-term effect of low fluence PDT by titrated dosage of verteporfin. The result of this study is crucial not only for therapeutic effect but also prevention of the complication in the future for CSC treatment.

Project ID:PC9808-0573
External Project ID:NSC98-2314-B182-020