January 2013

Amparo F, Sadrai Z, Jin Y, Alfonso-Bartolozzi B, Wang H, Shikari H, Ciolino JB, Chodosh J, Jurkunas U, Schaumberg DA, Dana R. Safety and efficacy of the multitargeted receptor kinase inhibitor pazopanib in the treatment of corneal neovascularization. Invest Ophthalmol Vis Sci 2013;54(1):537-44.Abstract
PURPOSE: To evaluate the safety and efficacy of topical pazopanib in the treatment of corneal neovascularization (CNV). METHODS: Twenty eyes of 20 patients with stable CNV were enrolled in a prospective, open label, noncomparative study and treated with topical pazopanib 0.5% for 3 weeks, and followed for 12 weeks. The primary endpoint was to determine the tolerability and safety of topical pazopanib in the treatment of CNV defined by the occurrence of ocular and systemic adverse events during the study. The secondary endpoint was to evaluate the effect of topical pazopanib on the reduction of (1) neovascular area (NA), defined as the area of the corneal vessels themselves, (2) invasion area (IA), defined as the fraction of the total cornea into which the vessels extend, (3) vessel length (VL), defined as the mean measurement of the extent of vessels from end to end, and (4) vessel caliber (VC), defined as the mean diameter of the corneal vessels. RESULTS: There were no severe adverse events following the use of topical pazopanib. Compared with the baseline visit, NA and VL showed a statistically significant decrease at week 3 (P = 0.02 and 0.01, respectively); and NA, IA, and VL statistically significantly decreased at week 12 (P = 0.03, 0.04, and <0.01, respectively). Visual acuity maintained without changes after the 12 week follow-up. CONCLUSIONS: This preliminary study suggests that topical treatment with pazopanib 0.5% is safe, well tolerated, and may have a role as an alternative for the treatment of CNV (ClinicalTrials.gov number, NCT01257750).
Dorr M, Bex PJ. Peri-saccadic natural vision. J Neurosci 2013;33(3):1211-7.Abstract
The fundamental role of the visual system is to guide behavior in natural environments. To optimize information transmission, many animals have evolved a non-homogeneous retina and serially sample visual scenes by saccadic eye movements. Such eye movements, however, introduce high-speed retinal motion and decouple external and internal reference frames. Until now, these processes have only been studied with unnatural stimuli, eye movement behavior, and tasks. These experiments confound retinotopic and geotopic coordinate systems and may probe a non-representative functional range. Here we develop a real-time, gaze-contingent display with precise spatiotemporal control over high-definition natural movies. In an active condition, human observers freely watched nature documentaries and indicated the location of periodic narrow-band contrast increments relative to their gaze position. In a passive condition under central fixation, the same retinal input was replayed to each observer by updating the video's screen position. Comparison of visual sensitivity between conditions revealed three mechanisms that the visual system has adapted to compensate for peri-saccadic vision changes. Under natural conditions we show that reduced visual sensitivity during eye movements can be explained simply by the high retinal speed during a saccade without recourse to an extra-retinal mechanism of active suppression; we give evidence for enhanced sensitivity immediately after an eye movement indicative of visual receptive fields remapping in anticipation of forthcoming spatial structure; and we demonstrate that perceptual decisions can be made in world rather than retinal coordinates.
Ferrari G, Hajrasouliha AR, Sadrai Z, Ueno H, Chauhan SK, Dana R. Nerves and neovessels inhibit each other in the cornea. Invest Ophthalmol Vis Sci 2013;54(1):813-20.Abstract
PURPOSE: To evaluate the regulatory cross-talk of the vascular and neural networks in the cornea. METHODS: b-FGF micropellets (80 ng) were implanted in the temporal side of the cornea of healthy C57Bl/6 mice. On day 7, blood vessels (hemangiogenesis) and nerves were observed by immunofluorescence staining of corneal flat mounts. The next group of mice underwent either trigeminal stereotactic electrolysis (TSE), or sham operation, to ablate the ophthalmic branch of the trigeminal nerve. Blood vessel growth was detected by immunohistochemistry for PECAM-1 (CD31) following surgery. In another set of mice following TSE or sham operation, corneas were harvested for ELISA (VEGFR3 and pigment epithelium-derived factor [PEDF]) and for quantitative RT-PCR (VEGFR3, PEDF, and CD45). PEDF, VEGFR3, beta-3 tubulin, CD45, CD11b, and F4/80 expression in the cornea were evaluated using immunostaining. RESULTS: No nerves were detected in the areas subject to corneal neovascularization, whereas they persisted in the areas that were neovessel-free. Conversely, 7 days after denervation, significant angiogenesis was detected in the cornea, and this was associated with a significant decrease in VEGFR3 (57.5% reduction, P = 0.001) and PEDF protein expression (64% reduction, P < 0.001). Immunostaining also showed reduced expression of VEGFR3 in the corneal epithelial layer. Finally, an inflammatory cell infiltrate, including macrophages, was observed. CONCLUSION: Our data suggest that sensory nerves and neovessels inhibit each other in the cornea. When vessel growth is stimulated, nerves disappear and, conversely, denervation induces angiogenesis. This phenomenon, here described in the eye, may have far-reaching implications in understanding angiogenesis.
Hamrah P, Cruzat A, Dastjerdi MH, Prüss H, Zheng L, Shahatit BM, Bayhan HA, Dana R, Pavan-Langston D. Unilateral herpes zoster ophthalmicus results in bilateral corneal nerve alteration: an in vivo confocal microscopy study. Ophthalmology 2013;120(1):40-7.Abstract
PURPOSE: Herpes zoster ophthalmicus (HZO), thought to be a unilateral disease, results in loss of corneal sensation, leading to neurotrophic keratopathy. This study aimed to analyze bilateral corneal nerve changes in patients with HZO by in vivo confocal microscopy (IVCM) and their correlation with corneal sensation as a measure of nerve function. DESIGN: Prospective, cross-sectional, controlled, single-center study. PARTICIPANTS: Twenty-seven eyes with the diagnosis of HZO and their contralateral clinically unaffected eyes were studied and compared with normal controls (n = 15). METHODS: In vivo confocal microscopy (Confoscan 4; Nidek Technologies, Gamagori, Japan) and corneal esthesiometry (Cochet-Bonnet; Luneau Ophthalmologie, Chartres, France) of the central cornea were performed bilaterally in all patients and controls. Patients were grouped into normal (>5.5 cm), mild (>2.5-5.5 cm), and severe (<2.5 cm) loss of sensation. MAIN OUTCOME MEASURES: Changes in corneal nerve density, total nerve number, main nerve trunks, branching, and tortuosity were evaluated after IVCM and were correlated to corneal sensation, disease duration, and number of recurrences. RESULTS: Eyes with herpes zoster ophthalmicus had a significant (P<0.001) decrease in total nerve length (595.8±358.1 vs. 2258.4±989.0 μm/frame), total number of nerves (5.4±2.8 vs. 13.1±3.8), number of main nerve trunks (2.3±1.1 vs. 4.7±1.2), and number of nerve branches (3.2±2.3 vs. 8.4±3.7) as compared with controls. In the contralateral clinically unaffected eyes, total nerve length (1053.1±441.4 μm/frame), total number of nerves (8.3±2.9), and main nerve trunks (3.1±1.0) also were decreased significantly as compared with controls (P<0.01). Reduced nerve density, total nerve count, main trunks, and tortuosity was correlated significantly with corneal sensation across all subgroups (P<0.001). CONCLUSIONS: Patients with unilateral HZO demonstrated a profound and significant bilateral loss of the corneal nerve plexus as compared with controls, demonstrating bilateral changes in a clinically unilateral disease. Loss of corneal sensation strongly correlated with subbasal nerve plexus alterations as shown by IVCM. FINANCIAL DISCLOSURE(S): The author(s) have no proprietary or commercial interest in any materials discussed in this article.
Lei H, Kazlauskas A. Detection of H2O2-mediated phosphorylation of kinase-inactive PDGFRα. Methods Enzymol 2013;528:189-94.Abstract
Platelet-derived growth factor (PDGF) receptor α (PDGFRα) belongs to the 58-member family of receptor tyrosine kinases and contributes to a variety of physiological and pathological settings. Activation of PDGFRα proceeds by at least two mechanisms. The traditional route involves PDGF-dependent dimerization and activation of the receptor's intrinsic kinase activity. The second mechanism proceeds intracellularly and involves reactive oxygen species and Src family kinases, which activate monomeric PDGFRα. Herein we describe an assay to investigate reactive oxygen species-mediated phosphorylation of PDGFRα that is independent of the receptor's intrinsic kinase activity.
Miller JW, Le Couter J, Strauss EC, Ferrara N. Vascular endothelial growth factor a in intraocular vascular disease. Ophthalmology 2013;120(1):106-14.Abstract
UNLABELLED: The vascular beds supplying the retina may sustain injury as a result of underlying disease such as diabetes, and/or the interaction of genetic predisposition, environmental insults, and age. The vascular pathologic features observed in different intraocular vascular diseases can be categorized broadly as proliferation, exemplified by proliferative diabetic retinopathy, leakage such as macular edema secondary to retinal vein occlusion, or a combination of proliferation and leakage, as seen in neovascular age-related macular degeneration (AMD). The World Health Organization has identified diabetic retinopathy and AMD as priority eye diseases for the prevention of vision loss in developed countries. The pathologic transformations of the retinal vasculature seen in intraocular vascular disease are associated with increased expression of vascular endothelial growth factor A (VEGF), a potent endothelial-specific mitogen. Furthermore, in model systems, VEGF alone is sufficient to trigger intraocular neovascularization, and its inhibition is associated with functional and anatomic improvements in the affected eye. Therapeutic interventions with effect on VEGF include intraocular capture and neutralization by engineered antibodies or chimeric receptors, downregulation of its expression with steroids, or alleviation of retinal ischemia, a major stimulus for VEGF expression, with retinal ablation by laser treatment. Data from prospective randomized clinical trials indicate that VEGF inhibition is a potent therapeutic strategy for intraocular vascular disease. These findings are changing clinical practice and are stimuli for further study of the basic mechanisms controlling intraocular angiogenesis. FINANCIAL DISCLOSURE(S): Proprietary or commercial disclosure may be found after the references.
Miller JW. Age-related macular degeneration revisited--piecing the puzzle: the LXIX Edward Jackson memorial lecture. Am J Ophthalmol 2013;155(1):1-35.e13.Abstract
PURPOSE: To present the current understanding of age-related macular degeneration (AMD) pathogenesis, based on clinical evidence, epidemiologic data, histopathologic examination, and genetic data; to provide an update on current and emerging therapies; and to propose an integrated model of the pathogenesis of AMD. DESIGN: Review of published clinical and experimental studies. METHODS: Analysis and synthesis of clinical and experimental data. RESULTS: We are closer to a complete understanding of the pathogenesis of AMD, having progressed from clinical observations to epidemiologic observations and clinical pathologic correlation. More recently, modern genetic and genomic studies have facilitated the exploration of molecular pathways. It seems that AMD is a complex disease that results from the interaction of genetic susceptibility with aging and environmental factors. Disease progression also seems to be driven by a combination of genetic and environmental factors. CONCLUSIONS: Therapies based on pathophysiologic features have changed the paradigm for treating neovascular AMD. With improved understanding of the underlying genetic susceptibility, we can identify targets to halt early disease and to prevent progression and vision loss.
Schrems-Hoesl LM, Schrems WA, Cruzat A, Shahatit BM, Bayhan HA, Jurkunas UV, Hamrah P. Cellular and subbasal nerve alterations in early stage Fuchs' endothelial corneal dystrophy: an in vivo confocal microscopy study. Eye (Lond) 2013;27(1):42-9.Abstract
PURPOSE: To analyze the morphology and density of corneal epithelial cells, keratocytes, and subbasal nerves, in patients with early stage Fuchs' endothelial corneal dystrophy (FECD) by in vivo confocal microscopy (IVCM). METHODS: IVCM (Confoscan 4, Nidek, Inc.) of the central cornea was performed in 30 corneas of 30 patients with early stage FECD and 13 corneas of 13 normal controls. Images were analyzed for morphology and density of the superficial and basal epithelial cells, keratocyte density, endothelial cell density (ECD), as well as subbasal corneal nerve parameters. Central corneal thickness (CCT) was measured in all patients and normals by ultrasound pachymetry. RESULTS: The ECD was significantly lower (-45.5%, P<0.001) in FECD patients as compared with controls. Total number of nerves and main nerve trunks were significantly reduced (-46.3%, P<0.001; -39.7%, P<0.001) in patients with FECD. Posterior keratocyte density was significantly higher in FECD patients (P<0.001). Significant inverse correlations were found between CCT and total number of nerves (r=-0.69, P<0.001), CCT and main nerve trunks (-0.47, P=0.016), as well as CCT and total nerve length (r=-0.62, P=0.006). Significant correlation was found between ECD and total number of nerves (r=0.44, P=0.012) as well as between ECD and main nerve trunks (r=0.65, P<0.001). CONCLUSIONS: IVCM demonstrates alterations in corneal innervation in patients with early stage FECD, suggesting a potential role of corneal nerves in the pathogenesis of FECD. Additional studies are required to investigate whether subbasal nerve alterations are caused by nonspecific corneal edema, from FECD-induced decrease in ECD, or potentially leading to loss of endothelial cells.
Theodoropoulou S, Brodowska K, Kayama M, Morizane Y, Miller JW, Gragoudas ES, Vavvas DG. Aminoimidazole carboxamide ribonucleotide (AICAR) inhibits the growth of retinoblastoma in vivo by decreasing angiogenesis and inducing apoptosis. PLoS One 2013;8(1):e52852.Abstract
5-Aminoimidazole-4-carboxamide-1-β-4-ribofuranoside (AICAR), an analog of AMP is widely used as an activator of AMP-kinase (AMPK), a protein that regulates the responses of the cell to energy change. Recently, we showed that AICAR-induced AMPK activation inhibits the growth of retinoblastoma cells in vitro by decreasing cyclins and by inducing apoptosis and S-phase arrest. In this study, we investigated the effects of AMPK activator AICAR on the growth of retinoblastoma in vivo. Intraperitoneal injection of AICAR resulted in 48% growth inhibition of Y79 retinoblastoma cell tumors in mice. Tumors isolated from mice treated with AICAR had decreased expression of Ki67 and increased apoptotic cells (TUNEL positive) compared with the control. In addition, AICAR treatment suppressed significantly tumor vessel density and macrophage infiltration. We also showed that AICAR administration resulted in AMPK activation and mTOR pathway inhibition. Paradoxically observed down-regulation of p21, which indicates that p21 may have a novel function of an oncogene in retinoblastoma tumor. Our results indicate that AICAR treatment inhibited the growth of retinoblastoma tumor in vivo via AMPK/mTORC1 pathway and by apoptogenic, anti-proliferative, anti-angiogenesis mechanism. AICAR is a promising novel non-chemotherapeutic drug that may be effective as an adjuvant in treating Retinoblastoma.