Effects of PDT on the blood-retinal-barrier
and therapeutical consequences
Stefan Mennel (Marburg)
Ocular photodynamic therapy (PDT) is a well established clinical treatment for choroidal neovascularization
(CNV) secondary to age-related macular degeneration (AMD), pathologic
myopia as well as other ocular pathologies. The combination with intravitreal triamcinolone
(IVTA) or anti-VEGF (vascular endothelial growth factor) has shown better results compared to
PDT as monotherapy. Succession and timepoint of PDT and intravitreal application of IVTA or
anti-VEGF is variable for previous publications and presentations missing consideration of
pathophysiologic mechanisms.
A literature review and own clinical and laboratory examinations were performed to evaluate
the pathophysiologic influence of PDT and adjuvants to the CNV and the outer blood-retinal
barrier (BRB). Optical coherence tomography (OCT) was performed before PDT and at 2 as well as 7 days after PDT to determine
changes in the neuroarchitecture.
Our OCT results demonstrated an immediate transient serous retinal detachment due to fluid accumulation at the treated
area in all cases. Laboratory examinations presented a breakdown of the outer BRB function immediately following
verteporfin application and consecutive non-thermal laser treatment.
As IVTA and anti-VEGF resolves intra- and subretinal fluid and stabilizes the BRB the combined treatment does not only
represent the addition of two treatment strategies, but reflects a usefull combination of two interacting pathophysiologic
pathways. Furthermore, as VEGF is known to be raised due to PDT a combined treatment seems advantageous especially
when IVTA or anti-VEGF has been applicated prior to PDT.
Our first OCT results of combined treatment (anti-VEGF has been injected intravitreally one week prior to PDT) demonstrated
in contrast to PDT as monotherapy, clearly no serous detachment following PDT, reducing accumulation of fluid,
transudates, and possibly mediators, inflammatory cells and also VEGF.
These clinical and experimental results precisely demonstrates that the combined treatment presents a useful interacting
treatment procedure. Because up to now there is a high variance of timepoint and sequence of PDT and intraocular
application of adjuvants we will present here our novel treatment guideline for combined treatment. To achieve the best
therapeutic effect according to the pathophysiologic effect adjuvants should be administered 2 to 7 days prior to PDT.