Mark S. Blumenkranz

Bio: Mark S. Blumenkranz is an academic researcher from Stanford University. The author has contributed to research in topics: Vitrectomy & Retinal detachment. The author has an hindex of 61, co-authored 261 publications receiving 14385 citations. Previous affiliations of Mark S. Blumenkranz include Bascom Palmer Eye Institute & University of Miami.

Randomized controlled study of an intravitreous dexamethasone drug delivery system in patients with persistent macular edema.

Abstract: Objective To evaluate a dexamethasone intravitreous drug delivery system (DDS) in patients with persistent (≥90 days despite treatment) macular edema. Methods This 6-month study randomized 315 patients with persistent macular edema with best-corrected visual acuity (BCVA) of 20/40 to 20/200 in the study eye to observation or a single treatment with dexamethasone DDS, 350 or 700 μg. Main Outcome Measures Proportion of patients achieving a BCVA improvement of 10 or more letters or 15 or more letters, safety measures, change in fluorescein angiographic leakage, and central retinal thickness. Results At day 90 (primary end point), an improvement in BCVA of 10 letters or more was achieved by a greater proportion of patients treated with dexamethasone DDS, 700 μg (35%) or 350 μg (24%), than observed patients (13%; P P = .04 vs 350-μg group); an improvement in BCVA of 15 letters or more was achieved in 18% of patients treated with dexamethasone DDS, 700 μg, vs 6% of observed patients ( P = .006). Results were similar in patients with diabetic retinopathy, vein occlusion, or uveitis or Irvine-Gass syndrome. During 3 months of observation, 11% of treated patients and 2% of observed patients had intraocular pressure increases of 10 mm Hg or higher. Conclusion In persistent macular edema, a single dexamethasone DDS treatment produced statistically significant BCVA improvements 90 days after treatment and was well tolerated for 180 days. Application to Clinical Practice Dexamethasone DDS, 700 μg, may have potential as a treatment for persistent macular edema. Trial Registration clinicaltrials.gov Identifier:"http://clinicaltrials.gov/show/NCT00035906"

Medscape

Abstract: Secret History: Return of the Black Death Channel 4, 7-8pm In 1348 the Black Death swept through London, killing people within days of the appearance of their first symptoms. Exactly how many died, and why, has long been a mystery. This Secret History documentary follows experts as they pick through the evidence and reveal why the plague killed on such a scale. And they ask, what might be coming next?

Ranibizumab for Neovascular Age-Related Macular Degeneration

Abstract: Background Ranibizumab — a recombinant, humanized, monoclonal antibody Fab that neutralizes all active forms of vascular endothelial growth factor A — has been evaluated for the treatment of neovascular age-related macular degeneration. Methods In this multicenter, 2-year, double-blind, sham-controlled study, we randomly assigned patients with age-related macular degeneration with either minimally classic or occult (with no classic lesions) choroidal neovascularization to receive 24 monthly intravitreal injections of ranibizumab (either 0.3 mg or 0.5 mg) or sham injections. The primary end point was the proportion of patients losing fewer than 15 letters from baseline visual acuity at 12 months. Results We enrolled 716 patients in the study. At 12 months, 94.5% of the group given 0.3 mg of ranibizumab and 94.6% of those given 0.5 mg lost fewer than 15 letters, as compared with 62.2% of patients receiving sham injections (P<0.001 for both comparisons). Visual acuity improved by 15 or more letters in 24.8% of the 0.3-mg group and 33.8% of the 0.5-mg group, as compared with 5.0% of the sham-injection group (P<0.001 for both doses). Mean increases in visual acuity were 6.5 letters in the 0.3-mg group and 7.2 letters in the 0.5-mg group, as compared with a decrease of 10.4 letters in the sham-injection group (P<0.001 for both comparisons). The benefit in visual acuity was maintained at 24 months. During 24 months, presumed endophthalmitis was identified in five patients (1.0%) and serious uveitis in six patients (1.3%) given ranibizumab. Conclusions Intravitreal administration of ranibizumab for 2 years prevented vision loss and improved mean visual acuity, with low rates of serious adverse events, in patients with minimally classic or occult (with no classic lesions) choroidal neovascularization secondary to age-related macular degeneration. (ClinicalTrials.gov number, NCT00056836.)

Imaging and photodynamic therapy: mechanisms, monitoring, and optimization.

Abstract: 1.1 Photodynamic Therapy and Imaging The purpose of this review is to present the current state of the role of imaging in photodynamic therapy (PDT). In order for the reader to fully appreciate the context of the discussions embodied in this article we begin with an overview of the PDT process, starting with a brief historical perspective followed by detailed discussions of specific applications of imaging in PDT. Each section starts with an overview of the specific topic and, where appropriate, ends with summary and future directions. The review closes with the authors’ perspective of the areas of future emphasis and promise. The basic premise of this review is that a combination of imaging and PDT will provide improved research and therapeutic strategies. PDT is a photochemistry-based approach that uses a light-activatable chemical, termed a photosensitizer (PS), and light of an appropriate wavelength, to impart cytotoxicity via the generation of reactive molecular species (Figure 1a). In clinical settings, the PS is typically administered intravenously or topically, followed by illumination using a light delivery system suitable for the anatomical site being treated (Figure 1b). The time delay, often referred to as drug-light interval, between PS administration and the start of illumination with currently used PSs varies from 5 minutes to 24 hours or more depending on the specific PS and the target disease. Strictly speaking, this should be referred to as the PS-light interval, as at the concentrations typically used the PS is not a drug, but the drug-light interval terminology seems to be used fairly frequently. Typically, the useful range of wavelengths for therapeutic activation of the PS is 600 to 800 nm, to avoid interference by endogenous chromophores within the body, and yet maintain the energetics necessary for the generation of cytotoxic species (as discussed below) such as singlet oxygen (1O2). However, it is important to note that photosensitizers can also serve as fluorescence imaging agents for which activation with light in the 400nm range is often used and has been extremely useful in diagnostic imaging applications as described extensively in Section 2 of this review. The obvious limitation of short wavelength excitation is the lack of tissue penetration so that the volumes that are probed under these conditions are relatively shallow. Open in a separate window Figure 1 (A) A schematic representation of PDT where PS is a photoactivatable multifunctional agent, which, upon light activation can serve as both an imaging agent and a therapeutic agent. (B) A schematic representation of the sequence of administration, localization and light activation of the PS for PDT or fluorescence imaging. Typically the PS is delivered systemically and allowed to circulate for an appropriate time interval (the “drug-light interval”), during which the PS accumulates preferentially in the target lesion(s) prior to light activation. In the idealized depiction here the PS is accumulation is shown to be entirely in the target tissue, however, even if this is not the case, light delivery confers a second layer of selectivity so that the cytotoxic effect will be generated only in regions where both drug and light are present. Upon localization of the PS, light activation will result in fluorescence emission which can be implemented for imaging applications, as well as generation cytotoxic species for therapy. In the former case light activation is achieved with a low fluence rate to generate fluorescence emission with little or no cytotoxic effect, while in the latter case a high fluence rate is used to generate a sufficient concentration of cytotoxic species to achieve biological effects.