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Higher irradiance and photodynamic therapy for age-related macular degeneration (an AOS thesis).

ABSTRACT: Photodynamic therapy (PDT) using verteporfin was the first pharmacologic therapy for neovascular age-related macular degeneration and changed the treatment paradigm for a major, blinding disease. The experimental work in the nonhuman primate was essential in developing treatment parameters for verteporfin PDT that could successfully occlude choroidal neovascularization with limited injury to the neural retina. Early in the preclinical primate studies, we hypothesized that higher irradiances could be used for ocular PDT than had been used in dermatology and other applications, which typically utilized an irradiance of 150 to 200 mW/cm(2). We set out to test the feasibility of irradiances up to 1800 mW/cm(2).PDT was applied to normal monkey eyes using verteporfin/benzoporphyrin derivative (BPD) (2 mg/kg) mixed with low-density lipoprotein in DMSO, and 692-nm light, with a spot size 1250mum, fluence approximately 50 J/cm(2), and irradiance varying from 150 (treatment time, 6 minutes) to 1800 mW/cm(2) (treatment time, 30 seconds). Photocoagulation lesions were applied using 514-nm and 692-nm laser light without drug, with irradiance of 18,750 to 200,000 mW/cm(2) and spot size of 500 mum. Treatment effect was evaluated by fundus photography, angiography, and light and electron microscopy with collagen denaturation as a marker of thermal injury.Verteporfin/BPD PDT at irradiances of 150 to 1800 mW/cm(2) showed no collagen denaturation in contrast to photocoagulation lesions without dye (irradiance 10-fold and higher).Verteporfin PDT could safely be performed at higher irradiances, permitting a clinically practical therapy. Ultimately, clinical trials demonstrated that verteporfin PDT could limit moderate vision loss in neovascular age-related macular degeneration. Although anti-VEGF therapy has replaced PDT as a first-line therapy, PDT may still have a role, perhaps in combination therapies. Further investigations to optimize drug delivery and to better understand the molecular mechanisms of PDT effects in both choroidal neovascularization and retina will improve its application in macular diseases.

SUBMITTER: Miller JW

PROVIDER: S-EPMC2646424 | biostudies-literature | 2008

REPOSITORIES: biostudies-literature

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Higher irradiance and photodynamic therapy for age-related macular degeneration (an AOS thesis).

Miller Joan W JW

Transactions of the American Ophthalmological Society 20080101

<h4>Purpose</h4>Photodynamic therapy (PDT) using verteporfin was the first pharmacologic therapy for neovascular age-related macular degeneration and changed the treatment paradigm for a major, blinding disease. The experimental work in the nonhuman primate was essential in developing treatment parameters for verteporfin PDT that could successfully occlude choroidal neovascularization with limited injury to the neural retina. Early in the preclinical primate studies, we hypothesized that higher ...[more]

PMID: 19277246

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Project description:PurposeQuantification of retinal xanthophyll carotenoids in eyes with and without age-related macular degeneration (AMD) via macular pigment optical volume (MPOV), a metric for xanthophyll abundance from dual wavelength autofluorescence, plus correlations to plasma levels, could clarify the role of lutein (L) and zeaxanthin (Z) in health, AMD progression, and supplementation strategies.DesignCross-sectional observational study (NCT04112667).ParticipantsAdults ≥ 60 years from a comprehensive ophthalmology clinic, with healthy maculas or maculas meeting fundus criteria for early or intermediate AMD.MethodsMacular health and supplement use was assessed by the Age-related Eye Disease Study (AREDS) 9-step scale and self-report, respectively. Macular pigment optical volume was measured from dual wavelength autofluorescence emissions (Spectralis, Heidelberg Engineering). Non-fasting blood draws were assayed for L and Z using high-performance liquid chromatography. Associations among plasma xanthophylls and MPOV were assessed adjusting for age.Main outcome measuresAge-related macular degeneration presence and severity, MPOV in fovea-centered regions of radius 2.0° and 9.0°; plasma L and Z (μM/ml).ResultsOf 809 eyes from 434 persons (89% aged 60-79, 61% female), 53.3% eyes were normal, 28.2% early AMD, and 18.5% intermediate AMD. Macular pigment optical volume 2° and 9° were similar in phakic and pseudophakic eyes, which were combined for analysis. Macular pigment optical volume 2° and 9° and plasma L and Z were higher in early AMD than normal and higher still in intermediate AMD (P < 0.0001). For all participants, higher plasma L was correlated with higher MPOV 2° (Spearman correlation coefficient [Rs] = 0.49; P < 0.0001). These correlations were significant (P < 0.0001) but lower in normal (Rs = 0.37) than early and intermediate AMD (Rs = 0.52 and 0.51, respectively). Results were similar for MPOV 9°. Plasma Z, MPOV 2°, and MPOV 9° followed this same pattern of associations. Associations were not affected by supplement use or smoking status.ConclusionsA moderate positive correlation of MPOV with plasma L and Z comports with regulated xanthophyll bioavailability and a hypothesized role for xanthophyll transfer in soft drusen biology. An assumption that xanthophylls are low in AMD retina underlies supplementation strategies to reduce progression risk, which our data do not support. Whether higher xanthophyll levels in AMD are due to supplement use cannot be determined in this study.

Dataset Information

Higher irradiance and photodynamic therapy for age-related macular degeneration (an AOS thesis).

Publications

Higher irradiance and photodynamic therapy for age-related macular degeneration (an AOS thesis).

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