Karl G Csaky

Retina Foundation of the Southwest, Dallas, Texas, United States

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Publications (121)401.19 Total impact

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    ABSTRACT: This study assessed the safety, tolerability, and pharmacodynamics of emixustat hydrochloride (ACU-4429), a novel visual cycle modulator, in subjects with geographic atrophy associated with dry age-related macular degeneration. Subjects were randomly assigned to oral emixustat (2, 5, 7, or 10 mg once daily) or placebo (3:1 ratio) for 90 days. Recovery of rod photoreceptor sensitivity after a photobleach was measured by electroretinography. Safety evaluations included analysis of adverse events and ophthalmic examinations. Seventy-two subjects (54 emixustat and 18 placebo) were evaluated. Emixustat suppressed rod photoreceptor sensitivity in a dose-dependent manner. Suppression plateaued by Day 14 and was reversible within 7 days to 14 days after drug cessation. Most systemic adverse events were not considered treatment related. Dose-related ocular adverse events (chromatopsia, 57% emixustat vs. 17% placebo and delayed dark adaptation, 48% emixustat vs. 6% placebo) were mild to moderate in severity, and the majority resolved on study or within 7 days to 14 days after study drug cessation. Reversibility of these adverse events with long-term administration, however, is undetermined. In this Phase II study, emixustat produced a dose-dependent reversible effect on rod function that is consistent with the proposed mechanism of action. These results support further testing of emixustat for the treatment of geographic atrophy associated with dry age-related macular degeneration.
    No preview · Article · Apr 2015 · Retina (Philadelphia, Pa.)
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    ABSTRACT: To evaluate pazopanib eye drops in subjects with active subfoveal choroidal neovascularization (CNV) secondary to age-related macular degeneration (AMD). Multicountry, randomized, parallel-group, double-masked, active and placebo-controlled, dose-ranging study of eye drops. A total of 510 subjects (93% white; 58% female; mean age, 75.3 years) whose AMD was previously managed by anti-vascular endothelial growth factor intravitreal injections. Treatments administered for 52 weeks included placebo eye drops instilled 4 times daily (n = 73); pazopanib 5 mg/ml instilled 3 (n = 72) or 4 times daily (n = 74); pazopanib 10 mg/ml instilled 2 (n = 73), 3 (n = 73), or 4 times daily (n = 72); or ranibizumab injection administered once every 4 weeks (n = 73). In addition, for all eye drop treatment groups, open-label ranibizumab was administered as needed. The main outcome measures were best-corrected visual acuity (BCVA) and injection frequency assessed at week 52. Safety was assessed every 4 weeks and pazopanib plasma concentrations were determined at weeks 4 and 24. At week 52, pazopanib, with allowance for as-needed ranibizumab injections, was noninferior to monthly ranibizumab as well as to as-needed ranibizumab administered with placebo eye drops in maintaining BCVA (estimated BCVA gains of 0.3-1.8 vs. 1.4 vs. 0.2 letters, respectively). Pazopanib treatment did not reduce as-needed ranibizumab injections by ≥50% (prespecified efficacy criterion). At week 52, there were no clinically meaningful changes from baseline in retinal thickness or morphology, CNV size, or lesion characteristics on optical coherence tomography or fluorescein angiography. Complement factor H genotype had no effect on the responses to pazopanib and/or ranibizumab (BCVA, injection rate, or optical coherence tomography/fluorescein angiography changes). Steady-state concentrations of pazopanib in plasma seemed to be reached by week 4. The most common ocular adverse events related to pazopanib and ranibizumab were application site pain (3%) and injection site hemorrhage (1%), respectively. No treatment-related serious adverse events were reported. Pazopanib was well tolerated. Daily pazopanib eye drops in neovascular AMD subjects did not result in therapeutic benefit beyond that obtained with ranibizumab alone. Copyright © 2014 American Academy of Ophthalmology. Published by Elsevier Inc. All rights reserved.
    No preview · Article · Nov 2014 · Ophthalmology
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    ABSTRACT: Topical bevacizumab is a potential treatment modality for corneal neovascularization, and several recent studies have demonstrated its efficacy. No previous study of the pharmacokinetics of topical bevacizumab has been performed in human eyes. The purpose of this study is to investigate the pharmacokinetics of topical administration of bevacizumab in human eyes, and also to compare the pharmacokinetics of intravitreal bevacizumab injections with previously reported data. Twenty-two (22 eyes) were included in this study, and divided into four groups: eight patients received topical bevacizumab and aqueous samples were obtained 1 hour later during cataract extraction surgery (group 1), eight patients received topical bevacizumab and vitreous samples were obtained 1 day later during pars-plana vitrectomy (PPV) (group 2), three patients received intravitreal bevacizumab and vitreous samples were obtained during PPV (group 3). Vitreous samples from three patients who received no bevacizumab served as controls (group 4). All samples underwent enzyme-linked immunosorbent assay to detect bevacizumab. No bevacizumab was detected in the aqueous or vitreous of any topically treated eyes. The mean vitreal half-life for intravitreally injected bevacizumab was 4.9 days in four non-vitrectomized eyes and 0.66 days in one previously vitrectomized eye. Topically administered bevacizumab does not penetrate the cornea into the anterior chamber and vitreous cavity, indicating that topical use for treating corneal neovascularization has minimal risk of intraocular penetration and adverse events related to intraocular vascular endothelial growth factor inhibition. The half-life following intravitreal bevacizumab injection measured in this study is comparable to that of previous reports, and includes the first demonstration of a significantly reduced half-life following intravitreal injection in a previously vitrectomized eye.
    Full-text · Article · Oct 2013 · Albrecht von Graæes Archiv für Ophthalmologie
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    Full-text · Dataset · Jul 2013
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    Full-text · Dataset · Jul 2013
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    Full-text · Dataset · Jul 2013
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    Full-text · Dataset · Jul 2013
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    Full-text · Dataset · Jul 2013
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    ABSTRACT: PURPOSE: The accuracy of predicting conversion from early-stage age-related macular degeneration (AMD) to the advanced stages of choroidal neovascularization (CNV) or geographic atrophy (GA) was evaluated to determine whether inclusion of clinically relevant genetic markers improved accuracy beyond prediction using phenotypic risk factors alone. DESIGN: Cohort study. PARTICIPANTS: White, non-Hispanic subjects participating in the Age-Related Eye Disease Study (AREDS) sponsored by the National Eye Institute consented to provide a genetic specimen. Of 2415 DNA specimens available, 940 were from disease-free subjects and 1475 were from subjects with early or intermediate AMD. METHODS: DNA specimens from study subjects were genotyped for 14 single nucleotide polymorphisms (SNPs) in genes shown previously to associate with CNV: ARMS2, CFH, C3, C2, FB, CFHR4, CFHR5, and F13B. Clinical demographics and established disease associations, including age, sex, smoking status, body mass index (BMI), AREDS treatment category, and educational level, were evaluated. Four multivariate logistic models (phenotype; genotype; phenotype + genotype; and phenotype + genotype + demographic + environmental factors) were tested using 2 end points (CNV, GA). Models were fitted using Cox proportional hazards regression to use time-to-disease onset data. MAIN OUTCOME MEASURES: Brier score (measure of accuracy) was used to identify the model with the lowest prediction error in the training set. The most accurate model was subjected to independent statistical validation, and final model performance was described using area under the receiver operator curve (AUC) or C-statistic. RESULTS: The CNV prediction models that combined genotype with phenotype with or without age and smoking revealed superior performance (C-statistic = 0.96) compared with the phenotype model based on the simplified severity scale and the presence of CNV in the nonstudy eye (C-statistic = 0.89; P<0.01). For GA, the model that combined genotype with phenotype demonstrated the highest performance (AUC = 0.94). Smoking status and ARMS2 genotype had less of an impact on the prediction of GA compared with CNV. CONCLUSIONS: Inclusion of genotype assessment improves CNV prediction beyond that achievable with phenotype alone and may improve patient management. Separate assessments should be used to predict progression to CNV and GA because genetic markers and smoking status do not equally predict both end points. FINANCIAL DISCLOSURE(S): Proprietary or commercial disclosure may be found after the references.
    No preview · Article · Mar 2013 · Ophthalmology
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    ABSTRACT: OBJECTIVE: To develop a clinical classification system for age-related macular degeneration (AMD). DESIGN: Evidence-based investigation, using a modified Delphi process. PARTICIPANTS: Twenty-six AMD experts, 1 neuro-ophthalmologist, 2 committee chairmen, and 1 methodologist. METHODS: Each committee member completed an online assessment of statements summarizing current AMD classification criteria, indicating agreement or disagreement with each statement on a 9-step scale. The group met, reviewed the survey results, discussed the important components of a clinical classification system, and defined new data analyses needed to refine a classification system. After the meeting, additional data analyses from large studies were provided to the committee to provide risk estimates related to the presence of various AMD lesions. MAIN OUTCOME MEASURES: Delphi review of the 9-item set of statements resulting from the meeting. RESULTS: Consensus was achieved in generating a basic clinical classification system based on fundus lesions assessed within 2 disc diameters of the fovea in persons older than 55 years. The committee agreed that a single term, age-related macular degeneration, should be used for the disease. Persons with no visible drusen or pigmentary abnormalities should be considered to have no signs of AMD. Persons with small drusen (<63 μm), also termed drupelets, should be considered to have normal aging changes with no clinically relevant increased risk of late AMD developing. Persons with medium drusen (≥63-<125 μm), but without pigmentary abnormalities thought to be related to AMD, should be considered to have early AMD. Persons with large drusen or with pigmentary abnormalities associated with at least medium drusen should be considered to have intermediate AMD. Persons with lesions associated with neovascular AMD or geographic atrophy should be considered to have late AMD. Five-year risks of progressing to late AMD are estimated to increase approximately 100 fold, ranging from a 0.5% 5-year risk for normal aging changes to a 50% risk for the highest intermediate AMD risk group. CONCLUSIONS: The proposed basic clinical classification scale seems to be of value in predicting the risk of late AMD. Incorporating consistent nomenclature into the practice patterns of all eye care providers may improve communication and patient care. FINANCIAL DISCLOSURE(S): The author(s) have no proprietary or commercial interest in any materials discussed in this article.
    Full-text · Article · Jan 2013 · Ophthalmology
  • Karl G Csaky

    No preview · Article · Mar 2012 · Retina (Philadelphia, Pa.)
  • Karl G. Csaky
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    ABSTRACT: The development of new drugs and drug delivery devices for the treatment of posterior eye diseases is critically dependent on the potential for that drug to be approved by the United States Food and Drug Administration (FDA). This approval process is predicated on the successful achievement of endpoints in large multicenter clinical trials. This chapter will discuss the history and evolving nature of endpoints for these clinical trials. Updates on recent novel endpoints will be discussed as well as the potential for the use of readouts from various imaging tools of the retina as FDA acceptable endpoints for clinical trials.
    No preview · Chapter · Jul 2011
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    ABSTRACT: To compare the pharmacokinetics and tissue response between intravitreal and microcannulation injections into the suprachoroidal space using bevacizumab. Sixty-two pigs were studied. Either a pars plana intravitreal bevacizumab or a viscoelastic-enhanced microcannula suprachoroidal injection was performed with either 1.25 mg (group 1) or 3 mg (group 2). In group 1, six animals were euthanatized at 0.5, 7, 30, 60, 90, and 120 days after injection (n = 36). In group 2, six animals were euthanatized at 0.5, 7, 14, and 32 days (n = 24). Eyes were enucleated, dissected, and snap-frozen, or they were fixed for histology. Analysis of drug tissue levels was performed at two separate laboratories using masked specimens. Both laboratories were confirmatory. Intravitreal bevacizumab pharmacokinetics demonstrated a gradual decline in tissue levels over 30 to 60 days in both groups 1 and 2. In addition, suprachoroidal bevacizumab tissue levels declined rapidly and were not measurable at or beyond 7 days. Vitreitis and granulomatous vasculitis were noted in 7 of 30 intravitreal injection eyes. Immunohistology suggested a distinctive drug distribution. Direct intravitreal injection of bevacizumab has a more sustained pharmacologic profile than does a similar dose delivered to the suprachoroidal space. Intravitreal injections distributed more to the inner retina, whereas suprachoroidal delivery occurred primarily at the choroid, retinal pigment epithelium, and photoreceptor outer segments. Sustained release formulation of larger biological molecules should be considered to optimize suprachoroidal delivery. Inflammation from injections is granulomatous, seen only with intravitreal injections, and may result from either an altered immune response or a dose-related effect.
    Preview · Article · Mar 2011 · Investigative ophthalmology & visual science
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    ABSTRACT: We recently demonstrated increased frequency and growth potential of late outgrowth endothelial progenitor cells (OECs) in patients with neovascular age-related macular degeneration (nvAMD). This study investigated the effects of short- and long-term in vitro inhibition of vascular endothelial growth factor (VEGF) Receptor-2 (VEGFR-2) signaling by SU5416 and other inhibitors of the VEGF signaling pathway in OECs. OECs, from the peripheral blood of patients with nvAMD, and human umbilical vein endothelial cells were grown in the presence of SU5416, other VEGFR-2 tyrosine kinase inhibitors (TKIs), and inhibitors of phosphatidylinositol 3'-Kinase (PI3K)/protein kinase B (Akt) and protein kinase C (PKC) in complete angiogenic medium. Apotosis was assessed after 48 h using the fluorescein isothiocyanate Annexin V method. Cell counts were performed for 10 days, and features of senescence were analyzed using senescence-associated β-galactosidase staining, the telomeric repeat amplification protocol for telomerase activity, Southern blot analysis for mean telomere length, flow cytometric analysis for cell-cycle arrest, and western blot for p53 and p21. Control OECs, cells treated for 7 days with inhibitors, as well as naturally senescent OECs were analyzed for expression of different endothelial antigens, including VEGFR-2 and the receptor for stromal cell-derived factor 1, chemokine receptor 4 (CXCR-4). Migration in vitro to VEGF and stromal cell-derived factor 1 of OECs was assessed. SU5416, other VEGFR-2 TKIs, and inhibitors of PI3K, Akt, and PKC induced apoptosis, inhibited long-term proliferation, reduced telomerase activity, and induced premature senescence and cell-cycle arrest in OECs as well as in human umbilical vein endothelial cells. Naturally senescent cells and cells rendered senescent by VEGFR-2 TKIs had reduced VEGFR-2 and CXCR-4 expression and demonstrated reduced migratory ability to VEGF. This study demonstrates apoptosis upon short-term inhibition and inhibition of long-term survival of OECs from patients with nvAMD by SU5416, presumably via PI3K/Akt and/or PKC-mediated reduction in telomerase activity and subsequent induction of premature senescence, which is accompanied by impaired endothelial activity. Therefore, induction of premature senescence in endothelial cells may represent a potential therapeutic target in nvAMD.
    Preview · Article · Jan 2011 · Molecular vision
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    Full-text · Article · Nov 2010 · Investigative ophthalmology & visual science
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    ABSTRACT: The goal of this study was to examine elimination pathways when delivering subconjunctivally administered hydrophilic agents to the retinas of rat eyes. The distribution of sodium fluorescein released from an episcleral implant was compared in live and postmortem eyes. Elimination of the subconjunctivally administered hydrophilic agent IgG through blood and lymphatic vessels was investigated by immunohistochemistry. Additionally, lymphatic elimination of subconjunctivally injected sodium fluorescein was quantitatively evaluated. NaFl released from an episcleral implant was successfully delivered to the subretinal space in the postmortem eye but failed to do so in the live eye. Immunohistochemical visualization of the conjunctival tissue demonstrated dense distribution of blood and lymphatic vessels while also confirming the elimination of subconjunctivally administered IgG through these same vessels. The lymphatic elimination rate after injection of 75.6 μg of a hydrophilic agent, sodium fluorescein, into the subconjunctival space was determined to be 105 ng/min between 30 and 60 minutes. Conjunctival blood and lymphatic vessel elimination considerably limit transscleral hydrophilic drug delivery to the retina.
    No preview · Article · Oct 2010 · Investigative ophthalmology & visual science
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    ABSTRACT: Retinal pigment epithelium (RPE)-derived membranous debris named blebs, may accumulate and contribute to sub-RPE deposit formation, which is the earliest sign of age-related macular degeneration (AMD). Oxidative injury to the RPE might play a significant role in AMD. However, the underlying mechanisms are unknown. We previously reported that hydroquinone (HQ), a major pro-oxidant in cigarette smoke, foodstuff, and atmospheric pollutants, induces actin rearrangement and membrane blebbing in RPE cells as well as sub-RPE deposits in mice. Here, we show for the first time that phosphorylated Heat shock protein 27 (Hsp27), a key regulator of actin filaments dynamics, is up-regulated in RPE from patients with AMD. Also, HQ-induced nonlethal oxidative injury led to Hsp27mRNA up-regulation, dimer formation, and Hsp27 phosphorylation in ARPE-19 cells. Furthermore, we found that a cross talk between p38 and extracellular signal-regulated kinase (ERK) mediates HQ-induced Hsp27 phosphorylation and actin aggregate formation, revealing ERK as a novel upstream mediator of Hsp27 phosphorylation. Finally, we demonstrated that Hsp25, p38, and ERK phosphorylation are increased in aging C57BL/6 mice chronically exposed to HQ, whereas Hsp25 expression is decreased. Our data suggest that phosphorylated Hsp27 might be a key mediator in AMD and HQ-induced oxidative injury to the RPE, which may provide helpful insights into the early cellular events associated with actin reorganization and bleb formation involved in sub-RPE deposits formation relevant to the pathogenesis of AMD.
    Full-text · Article · Sep 2010 · American Journal Of Pathology
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    Jessica E Chan · Tiffany A Pridgen · Karl G Csaky
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    ABSTRACT: We quantified episcleral drug clearance of sodium fluorescein (NaFl) in rats to examine the hypothesis that there is rapid clearance of episcleral water soluble drugs, and that this rapid clearance may limit the amount of drug that is able to reach the posterior segment from an episcleral location. 2 mm implants containing either 12 or 22 microg of NaFl were manufactured and in vitro release rates were determined. Implants were placed in the sub-Tenon's space and the amount of drug remaining in the conjunctiva/sclera/choroid complex (CSCC) at various time points was quantified following tissue solubilization and fluorescence quantification using a spectrofluorometer. Kinetics of NaFl clearance was determined in live animals, following euthanasia and in animals in which choroidal non-perfusion had been achieved with indocyanine green-enhanced 810 nm diode laser thrombosis of the choroidal vasculature. Choroidal non-perfusion in these laser-treated rats was verified with Concavalin-A staining of choroidal flatmounts. In vitro, >99% of drug was released by 25 min for the low dose implants, and by 60 min for the high dose implants. In vivo, both implant doses were >99% cleared from the episcleral tissue by 3 h. By 7 h, an average of only 0.14 +/- 0.131 ng of NaFl per mg of wet tissue weight (mean +/- SD) remained in the CSCC with the low dose implant, and 0.29 +/- 0.428 ng of NaFl per mg of wet tissue weight remained in animals with the high dose implant. By comparison, in euthanized animals at 7 h following sub-Tenon's implantation, 432.0 +/- 181.40 ng of NaFl per mg of wet tissue weight was in the episcleral tissue of animals with the low dose implant, and of 787.8 +/- 409.89 ng of NaFl per mg of wet tissue weight remained in the animals with the high dose implant. In live animals with selective thrombosis of the choroidal vasculature, the difference in the amount of drug remaining in the episcleral tissue as compared to control live animals was not significant at all time points for both implant doses. In conclusion, there is rapid clearance of episcleral NaFl delivered from a bioerodible sub-tenon's implant. The clearance mechanisms are dramatically reduced following euthanasia, suggesting that elimination is occurring via active physiologic mechanisms, rather than by passive diffusion clearance (CL(diff)) (Pfister et al., 2003). Interestingly, the choroid does not appear to play a prominent role as clearance of episcleral NaFl was not affected by elimination of choroidal blood flow. Further work is needed to delineate the pathways of episcleral drug clearance.
    Preview · Article · Apr 2010 · Experimental Eye Research
  • Karl G. Csaky
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    ABSTRACT: An abstract is unavailable. This article is available as HTML full text and PDF.
    No preview · Article · Dec 2009 · Evidence-Based Ophthalmology
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    Hyuncheol Kim · Shaun B Robinson · Karl G Csaky
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    ABSTRACT: The goal of this study was to determine the role of the neonatal Fc (FcRn) receptor in eliminating intravitreally administered full-length immunoglobulin G (IgG) across the blood-retinal barrier. FcRn receptor expression in normal and laser photocoagulated retinas was compared quantitatively by real-time RT-PCR. The distribution of intravitreally administered full-length IgG was investigated and compared in wild-type and FcRn knockout mouse eyes as well as normal and laser-photocoagulated rat eyes at several time points. Additionally, the pharmacokinetics of intravitreally injected full-length IgG and chicken immunoglobulin Y (IgY) was compared in the normal rat retina. Intravitreally administered full-length IgG overcame the inner limiting membrane and diffused into the deeper retinal structures in both normal and laser-photocoagulated retinas. Interestingly, IgG was eliminated across the blood-retinal barrier into the blood system in the normal retina, whereas IgY was not. In addition, full-length IgGs did not penetrate across the blood-retinal barrier in the FcRn knockout mouse. Intravitreally injected IgGs were eliminated into the blood system more rapidly in laser-photocoagulated eyes when compared to normal control eyes because of FcRn receptor upregulation in the laser-photocoagulated retina. FcRn plays an important role in eliminating intravitreally administered full-length IgGs across the blood-retina barrier into the systemic blood system.
    Preview · Article · Dec 2009 · Molecular vision

Publication Stats

5k Citations
401.19 Total Impact Points

Institutions

  • 2012-2014
    • Retina Foundation of the Southwest
      Dallas, Texas, United States
  • 2013
    • Texas Retina Associates
      Dallas, Texas, United States
  • 1994-2013
    • National Institutes of Health
      • Laboratory of Immunology
      베서스다, Maryland, United States
  • 2008-2011
    • Duke University
      Durham, North Carolina, United States
    • Duke University Medical Center
      • Department of Ophthalmology
      Durham, North Carolina, United States
  • 1996-2011
    • National Eye Institute
      베서스다, Maryland, United States
  • 2004
    • NEI Corporation
      Сомерсет, New Jersey, United States
  • 2002-2004
    • Bascom Palmer Eye Institute
      Miami, Florida, United States
  • 2003
    • University of Miami
      • Department of Ophthalmology
      كورال غيبلز، فلوريدا, Florida, United States
  • 1999
    • National Cancer Institute (USA)
      베서스다, Maryland, United States
  • 1997
    • McMaster University
      • Health Sciences Centre
      Hamilton, Ontario, Canada