Paul Hahn

Iron toxicity as a potential factor in AMD.

While it has been known for years that iron overload is associated with retinal degeneration in the context of ocular siderosis, intraocular hemorrhage, and the hereditary diseases aceruloplasminemia and pantothenate kinase associated neurodegeneration, recent evidence suggests that age-related macular degeneration (AMD) may also be exacerbated by retinal iron overload. In the retina, iron is necessary for normal cellular function. Iron overload, however, can cause retinal toxicity through the generation of oxygen free radicals. Histopathology of eyes with macular degeneration has shown elevated levels of iron in the retinal pigment epithelium, Bruch membrane, and within drusen, some of which was chelatable in vitro with deferoxamine. In this review, the authors summarize the evidence that iron overload may contribute to AMD pathogenesis. It is hoped that continued investigation of the role of iron and iron associated proteins in the retina will uncover clues to AMD pathogenesis and lead to new preventative or therapeutic options.

Preclinical evaluation and intraoperative human retinal imaging with a high-resolution microscope-integrated spectral domain optical coherence tomography device

Purpose: The authors have recently developed a high-resolution microscope-integrated spectral domain optical coherence tomography (MIOCT) device designed to enable OCT acquisition simultaneous with surgical maneuvers. The purpose of this report is to describe translation of this device from preclinical testing into human intraoperative imaging. Methods: Before human imaging, surgical conditions were fully simulated for extensive preclinical MIOCT evaluation in a custom model eye system. Microscope-integrated spectral domain OCT images were then acquired in normal human volunteers and during vitreoretinal surgery in patients who consented to participate in a prospective institutional review board–approved study. Microscope-integrated spectral domain OCT images were obtained before and at pauses in surgical maneuvers and were compared based on predetermined diagnostic criteria to images obtained with a high-resolution spectral domain research handheld OCT system (HHOCT; Bioptigen, Inc) at the same time point. Cohorts of five consecutive patients were imaged. Successful end points were predefined, including ≥80% correlation in identification of pathology between MIOCT and HHOCT in ≥80% of the patients. Results: Microscope-integrated spectral domain OCT was favorably evaluated by study surgeons and scrub nurses, all of whom responded that they would consider participating in human intraoperative imaging trials. The preclinical evaluation identified significant improvements that were made before MIOCT use during human surgery. The MIOCT transition into clinical human research was smooth. Microscope-integrated spectral domain OCT imaging in normal human volunteers demonstrated high resolution comparable to tabletop scanners. In the operating room, after an initial learning curve, surgeons successfully acquired human macular MIOCT images before and after surgical maneuvers. Microscope-integrated spectral domain OCT imaging confirmed preoperative diagnoses, such as full-thickness macular hole and vitreomacular traction, and demonstrated postsurgical changes in retinal morphology. Two cohorts of five patients were imaged. In the second cohort, the predefined end points were exceeded with ≥80% correlation between microscope-mounted OCT and HHOCT imaging in 100% of the patients. Conclusion: This report describes high-resolution MIOCT imaging using the prototype device in human eyes during vitreoretinal surgery, with successful achievement of predefined end points for imaging. Further refinements and investigations will be directed toward fully integrating MIOCT with vitreoretinal and other ocular surgery to image surgical maneuvers in real time.

Envelope residue 375 substitutions in simian-human immunodeficiency viruses enhance CD4 binding and replication in rhesus macaques.

Significance Simian–human immunodeficiency viruses (SHIVs) are an invaluable tool for assessing HIV-1 vaccines, developing therapeutic “cure” strategies, and understanding viral immunopathogenesis. However, only limited success has been achieved in creating SHIVs that incorporate HIV-1 envelopes (Envs) that retain the antigenic features of clinically relevant viruses. Here we focus on a critical residue of the CD4-binding region, Env375, which is under strong positive selection across the broad range of primate lentiviruses. We find that genotypic variation of residue 375 allows for the creation of pathogenic SHIVs that retain the antigenicity, tier 2 neutralization sensitivity, and persistence properties characteristic of primary HIV-1 strains. Taken together, our findings suggest a new paradigm for SHIV design and modeling with important applications to HIV-1 vaccine, cure, and pathogenesis research. Most simian–human immunodeficiency viruses (SHIVs) bearing envelope (Env) glycoproteins from primary HIV-1 strains fail to infect rhesus macaques (RMs). We hypothesized that inefficient Env binding to rhesus CD4 (rhCD4) limits virus entry and replication and could be enhanced by substituting naturally occurring simian immunodeficiency virus Env residues at position 375, which resides at a critical location in the CD4-binding pocket and is under strong positive evolutionary pressure across the broad spectrum of primate lentiviruses. SHIVs containing primary or transmitted/founder HIV-1 subtype A, B, C, or D Envs with genotypic variants at residue 375 were constructed and analyzed in vitro and in vivo. Bulky hydrophobic or basic amino acids substituted for serine-375 enhanced Env affinity for rhCD4, virus entry into cells bearing rhCD4, and virus replication in primary rhCD4 T cells without appreciably affecting antigenicity or antibody-mediated neutralization sensitivity. Twenty-four RMs inoculated with subtype A, B, C, or D SHIVs all became productively infected with different Env375 variants—S, M, Y, H, W, or F—that were differentially selected in different Env backbones. Notably, SHIVs replicated persistently at titers comparable to HIV-1 in humans and elicited autologous neutralizing antibody responses typical of HIV-1. Seven animals succumbed to AIDS. These findings identify Env–rhCD4 binding as a critical determinant for productive SHIV infection in RMs and validate a novel and generalizable strategy for constructing SHIVs with Env glycoproteins of interest, including those that in humans elicit broadly neutralizing antibodies or bind particular Ig germ-line B-cell receptors.

The Use of Optical Coherence Tomography in Intraoperative Ophthalmic Imaging

Optical coherence tomography (OCT) has transformed diagnostic ophthalmic imaging but until recently has been limited to the clinic setting. The development of spectral-domain OCT (SD-OCT), with its improved speed and resolution, along with the development of a handheld OCT scanner, enabled portable imaging of patients unable to sit in a conventional tabletop scanner. This handheld SD-OCT unit has proven useful in examinations under anesthesia and, more recently, in intraoperative imaging of preoperative and postoperative manipulations. Recently, several groups have pioneered the development of novel OCT modalities, such as microscope-mounted OCT systems. Although still immature, the development of these systems is directed toward real-time imaging of surgical maneuvers in the intraoperative setting. This article reviews intraoperative imaging of the posterior and anterior segment using the handheld SD-OCT and recent advances toward real-time microscope-mounted intrasurgical imaging.

Best practices for treatment of retinal vein occlusion.

Purpose of review Retinal vein occlusion (RVO) is a sight-threatening retinal vascular disorder associated with macular edema and neovascularization. Until recently, the standard of care for branch RVO-associated macular edema was grid laser photocoagulation and observation for central RVO-associated macular edema. Neovascularization was treated with scatter laser photocoagulation. The purpose of this article is to review recent findings that have changed our treatments of RVO. Recent findings The recent development of intravitreal pharmacotherapy has demonstrated benefit with anti-vascular endothelial growth factor (VEGF) agents and corticosteroids for the treatment of RVO-associated macular edema. The intravitreal use of FDA-approved ranibizumab (Lucentis) and a sustained release dexamethasone implant (Ozurdex), along with off-label bevacizumab (Avastin) and preservative-free triamcinolone, has significantly expanded our treatment options and replaced standard of care for treatment of RVO-associated macular edema. Whereas anti-VEGF agents can also induce rapid regression of neovascularization, scatter laser photocoagulation remains the standard of care to prevent neovascular complications. Summary Intravitreal pharmacotherapy has revolutionized our treatment of retinal vascular diseases, including RVO. Although these intravitreal agents are effective, our understanding of their specific indications and long-term roles is still evolving. Furthermore, until the underlying occlusive pathophysiology of RVO can be addressed, our treatments will be limited to temporizing therapies against a chronic disease.

Deficiency of Bax and Bak protects photoreceptors from light damage in vivo

AbstractPhotoreceptors of bax−/−bak−/− but neither bax−/− mice nor bak−/− mice are protected from developmental apoptosis, suggesting that bax−/−bak−/− photoreceptors may also be protected from pathologic apoptosis. To test this possibility, we exposed bax−/−bak−/− and bax−/− mice to bright light, which normally induces photoreceptor death. Photoreceptors in bax−/−bak−/− mice were protected from death compared to bax−/− mice as indicated by a reduction in the number of TUNEL-positive photoreceptor nuclei 24 h following light damage and almost complete preservation of photoreceptors 7 days following light damage. These results provide the first in vivo evidence that combined deficiency of Bax and Bak can rescue cells from a pathologic stimulus more effectively than Bax deficiency and suggest that combined deficiency of Bax and Bak may also protect cells from other insults.

Unprocessed real-time imaging of vitreoretinal surgical maneuvers using a microscope-integrated spectral-domain optical coherence tomography system

BackgroundWe have recently developed a microscope-integrated spectral-domain optical coherence tomography (MIOCT) device towards intrasurgical cross-sectional imaging of surgical maneuvers. In this report, we explore the capability of MIOCT to acquire real-time video imaging of vitreoretinal surgical maneuvers without post-processing modifications.MethodsStandard 3-port vitrectomy was performed in human during scheduled surgery as well as in cadaveric porcine eyes. MIOCT imaging of human subjects was performed in healthy normal volunteers and intraoperatively at a normal pause immediately following surgical manipulations, under an Institutional Review Board-approved protocol, with informed consent from all subjects. Video MIOCT imaging of live surgical manipulations was performed in cadaveric porcine eyes by carefully aligning B-scans with instrument orientation and movement. Inverted imaging was performed by lengthening of the reference arm to a position beyond the choroid.ResultsUnprocessed MIOCT imaging was successfully obtained in healthy human volunteers and in human patients undergoing surgery, with visualization of post-surgical changes in unprocessed single B-scans. Real-time, unprocessed MIOCT video imaging was successfully obtained in cadaveric porcine eyes during brushing of the retina with the Tano scraper, peeling of superficial retinal tissue with intraocular forceps, and separation of the posterior hyaloid face. Real-time inverted imaging enabled imaging without complex conjugate artifacts.ConclusionsMIOCT is capable of unprocessed imaging of the macula in human patients undergoing surgery and of unprocessed, real-time, video imaging of surgical maneuvers in model eyes. These capabilities represent an important step towards development of MIOCT for efficient, real-time imaging of manipulations during human surgery.

Safety profile of ocriplasmin for symptomatic vitreomacular adhesion: A comprehensive analysis of premarketing and postmarketing experiences

Purpose: After the recent approval of ocriplasmin by the Food and Drug Administration, postmarketing safety concerns have been raised by the vitreoretinal community. The American Society of Retina Specialists Therapeutic Surveillance Committee was commissioned to monitor postmarketing drug-related and device-related adverse events. The purpose of this report is to analyze the postmarketing safety experience in the context of available premarketing safety data. Methods: Periodic aggregate safety reports consisting of premarketing, or clinical trial, data (n = 999 injections) and postmarketing reports through July 16, 2013 (n = 4,387 injections), were retrospectively analyzed by the TSC. The aggregate data were analyzed to classify adverse events, and the postmarketing safety data for each event type were compared with the premarketing data. Results: Eight categories of adverse events were identified. Acute reduction in visual acuity attributable to either worsening of macular pathology or development of subretinal fluid, electroretinogram changes, dyschromatopsia, retinal tears and detachments, lens subluxation or phacodonesis, impaired pupillary reflex, and retinal vessel findings were reported in both the premarketing and postmarketing experiences. Ellipsoid zone (inner segment/outer segment) findings were only reported in the postmarketing experience. Rates of postmarketing reports were lower than in the premarketing data. Adverse events were generally transient, and characteristics of these adverse events were generally similar between the premarketing and postmarketing experience. Conclusion: Postmarket analyses are limited by significant underreporting, and in the case of ocriplasmin as a first in-class drug, they may not have captured safety events that have only more recently been identified. Nonetheless, postmarket analyses can identify the scope of potential safety events based on real-world experiences. Ocriplasmin administration should be guided by an appropriate and informed risk-benefit discussion with the patient. Ongoing active postmarket surveillance by all practitioners will continue to be critical to better understand this safety profile.

Age-dependent and gender-specific changes in mouse tissue iron by strain

Iron is necessary for life but also a potent pro-oxidant implicated in the pathogenesis of age-related diseases. We sought to determine if iron levels change with age and by sex in various tissues from several commonly studied mouse strains. Brain, liver, heart, retina, and retinal pigment epithelium (RPE)/choroid were dissected from male and female mice of young adult (2-6 month old) and aged (16-19 month old) C57BL/6, DBA/2J, and BALB/c mice. Iron was quantified through a chromagen-based spectrophotometric method or through atomic absorption spectrophotometry for increased sensitivity. Brain, liver, and heart iron increased by 30-70% in aged vs. young adult groups of all strains, while retina and RPE/choroid iron had variable age-related changes. Significant gender differences were observed in BALB/c and DBA/2J strains. Males had as much as 2- to 3-fold more brain, RPE/choroid, and retinal iron, while females had as much as 2- to 3-fold more liver iron. There was no significant gender difference observed in heart iron. The different profiles of change between gender and among strains suggest that hormones and genetics influence iron regulation with aging. Future manipulation of iron levels in mice will test the role of iron in aging and disease, and the data reported herein will be essential in directing such manipulations.

Aflibercept-Related Sterile Inflammation

All injections were performed with standard techniques based on survey responses. Povidone-iodine 5% was applied before injection in all cases. Thirteen of 15 eyes were administered topical anesthesia, and 2 eyes were given subconjunctival lidocaine. All eyes were injected with the Becton Dickinson (Franklin Lakes, NJ) 1-ml Luer-Lok syringe included in the aflibercept packaging. The majority of eyes were injected in the superotemporal quadrant (12 of 15 eyes) and with a 32-G needle (13 of 15 eyes), while the remainder were injected in the inferotemporal quadrant (3 of 15 eyes) and with a 30-G needle (2 of 15 eyes). These differences likely represent individual practice pattern differences and are not an implication of these techniques. Five physicians practicing in the Northeast, the Southeast, and the Southern United States reported cases of sterile inflammation. Three physicians practiced in the same retina group, and 9 of 15 cases (60%) were reported by a single retina specialist in this practice, consistent with a clustering pattern previously reported with other intravitreal therapies. 2 All cases were attributed to 5 separate drug lots, with 3 lots accounting for 13 of 15 cases. All but 1 patient experienced symptoms within 3 days. Visual acuity generally recovered to baseline levels with nearly identical mean visual acuities at baseline (0.4 logarithm of the minimum angle of resolution) and after resolution (0.32 logarithm of the minimum angle of resolution) and a mean time to resolution of 30 days. No patient lost 1 Snellen line of visual acuity. In contrast with previous reports associating sterile inflammation from other intravitreal therapies with painless loss of vision, 3 9 of these 15 aflibercept-related cases (60%) presented with pain. Redness was noted only in eyes presenting with pain and in 6 of these 9 painful cases. It is possible that aflibercept-related sterile inflammation may be associated with higher rates of pain than previously reported. Alternatively, this difference may reflect differences in the treatment cohorts. Distinguishing between infectious and sterile endophthalmitis was at the discretion of the treating physician. Although all reported cases were culture negative, some of the cases treated with intravitreal antibiotics may have represented culture-negative infectious endophthalmitis, which is associated with increased pain, and not true sterile inflammation. However, 5 of 9 cases associated with pain were treated with vitreous tap and intravitreal antibiotic injection, and the remaining 4 cases were treated with topical steroids only, suggesting that potential misclassification of these symptoms is not fully responsible for this difference. It is likely that patients presenting with more pain were biased toward an initial diagnosis of infectious endophthalmitis (treated with tap/antibiotic injection) compared with those patients managed with topical steroids alone. Small sample size, clinical variation, and the limitations of voluntary reporting preclude definitive conclusions. Subgroup analysis did not detect any variables significantly affecting visual outcome or number of days to resolution (Tables 4 and 5; available at http://www.aaojournal.org). This letter serves as a descriptive case series to better understand the clinical characteristics of a cluster of aflibercept-related sterile inflammation. The manufacturer reports that approximately 30 000 injections had been administered during the reporting period, corresponding with a sterile inflammation rate of approximately 0.05%. Although there may certainly be additional, nonreported cases resulting in a higher actual rate, this frequency lies within the range documented by pivotal, prospective trials with aflibercept and other intravitreal agents and by retrospective analyses (Tables 6 and 7; available at http://www.aaojournal.org). The manufacturer continued to closely observe without public recalls or testing, and use of aflibercept has continued without persistent reports of unexpected rates of complications. The American Society of Retina Specialists Therapeutic Surveillance Subcommittee strongly urges practitioners to actively participate in postmarket surveillance of drug- and device-associated adverse events.