Ocular Photodynamic Therapy – Standard Applications and New Indications (Part 2)

Abstract

Photodynamic therapy (PDT) has become a well-established treatment for vascular forms of age-related macular degeneration (AMD). The implementation of evidence-based medicine principles into the treatment regimen of AMD seems to be immensly important, since AMD continues to be the most frequent cause of blindness among patients older than 65 years in industrialized countries. Numerous randomized prospective studies demonstrated high levels of evidence for the efficacy of various treatment approaches such as laser photocoagulation, PDT, subretinal surgery or novel anti-angiogenic drugs [Arch Ophthalmol 2006;124:597–599]. The high evidence shown by these studies supported the rationale to use PDT also in additional, less frequent, vasoproliferative diseases. Although these ‘case series’ and ‘individual case control studies’ have a low level of evidence, they give us important information for treatment decisions in these rare conditions. The goal of this survey is to review the current literature regarding PDT in vasoproliferative and exudative ocular diseases outside AMD. Many studies modified the treatment parameters of PDT to address the specific pathology of the underlying disease. Table 1 summarizes the diseases and treatment parameters that are described in this part 2, the entire table of this review is included in part 1 (www.karger.com/doi/10.1159/ 000101922).

Combined intravitreal anti‐vascular endothelial growth factor (Avastin®) and photodynamic therapy to treat retinal juxtapapillary capillary haemangioma

“…Similar findings have been described previously in studies demonstrating that the application of anti‐VEGF 5–8 days prior to PDT counteracts early PDT‐related pathophysiological alterations (Schmidt‐Erfurth et al. 2003; Mennel et al. 2005, 2007a, 2007b).…”

“…Possible side‐effects caused by PDT monotherapy, such as retinal pigment epithelium alterations in young patients, may be reduced by less retreament (Parodi et al. 2007; Mennel et al. 2006, 2007a, 2007b).…”

“…2006; Avery et al. 2006), the patient gave her informed consent to a combined treatment with bevacizumab and PDT (Mennel et al. 2007a, 2007b).…”

Photochemically stimulated drug delivery increases the cytotoxicity and specificity of EGF–saporin

“…PDT is today a treatment modality for cancer (Dolmans et al 2003) and age-related macular degeneration (AMD) (Mennel et al 2007a, Mennel et al 2007b. However, the method is also under evaluation for the treatment of psoriasis (Szeimies et al 2002), rheumatoid arthritis (Hansch et al 2008) and microbial infections (Jori et al 2006).…”

Alternative approach to laser methods of treating vascular pathologies of the eye

“…43,44 As a result of hydrolytic leakage of the enzyme and intracellular lysis, damage of the lysozomes with release of the PS from the vessels is observed, and this can cause increased sensitivity to PDT-damage of the RPE cells, followed by detachment of the neurosensor retina, breakdown of the outer hemoretinal barrier, and an increase of the concentration of the angiogenesis-growth factor VEGF. 45 Hydrophilic PSs can be transported both directly by the bloodstream and in liposomes (lipid bubbles). Because of their affinity to albumin, hydrophilic PSs remain within the bloodstream even at high doses, without accumulating in the peripheral tissues (with a slight tendency to diffuse into the cytoplasm through the plasma membrane), 20 thereby causing less secondary collateral damage by comparison with lipophilic verteporfin.…”