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Drzyzga Ł, Śpiewak D, Dorecka M, Wyględowska-Promieńska D. Available Therapeutic Options for Corneal Neovascularization: A Review. Int J Mol Sci 2024; 25:5479. [PMID: 38791518 PMCID: PMC11121997 DOI: 10.3390/ijms25105479] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2024] [Revised: 05/07/2024] [Accepted: 05/15/2024] [Indexed: 05/26/2024] Open
Abstract
Corneal neovascularization can impair vision and result in a poor quality of life. The pathogenesis involves a complex interplay of angiogenic factors, notably vascular endothelial growth factor (VEGF). This review provides a comprehensive overview of potential therapies for corneal neovascularization, covering tissue inhibitors of metalloproteinases (TIMPs), transforming growth factor beta (TGF-β) inhibitors, interleukin-1L receptor antagonist (IL-1 Ra), nitric oxide synthase (NOS) isoforms, galectin-3 inhibitors, retinal pigment epithelium-derived factor (PEDF), platelet-derived growth factor (PDGF) receptor inhibitors, and surgical treatments. Conventional treatments include anti-VEGF therapy and laser interventions, while emerging therapies such as immunosuppressive drugs (cyclosporine and rapamycin) have been explored. Losartan and decorin are potential antifibrotic agents that mitigate TGF-β-induced fibrosis. Ocular nanosystems are innovative drug-delivery platforms that facilitate the targeted release of therapeutic agents. Gene therapies, such as small interfering RNA and antisense oligonucleotides, are promising approaches for selectively inhibiting angiogenesis-related gene expression. Aganirsen is efficacious in reducing the corneal neovascularization area without significant adverse effects. These multifaceted approaches underscore the corneal neovascularization management complexity and highlight ideas for enhancing therapeutic outcomes. Furthermore, the importance of combination therapies and the need for further research to develop specific inhibitors while considering their therapeutic efficacy and potential adverse effects are discussed.
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Affiliation(s)
- Łukasz Drzyzga
- Department of Ophthalmology, Prof. K. Gibiński University Clinical Center, Medical University of Silesia, 40-055 Katowice, Poland
- Clinical Ophthalmology Center Okolux, 40-754 Katowice, Poland
| | - Dorota Śpiewak
- Department of Ophthalmology, Prof. K. Gibiński University Clinical Center, Medical University of Silesia, 40-055 Katowice, Poland
- Clinical Ophthalmology Center Okolux, 40-754 Katowice, Poland
| | - Mariola Dorecka
- Department of Ophthalmology, Prof. K. Gibiński University Clinical Center, Medical University of Silesia, 40-055 Katowice, Poland
- Department of Ophthalmology, Faculty of Medical Sciences in Katowice, Medical University of Silesia, 40-514 Katowice, Poland
| | - Dorota Wyględowska-Promieńska
- Department of Ophthalmology, Prof. K. Gibiński University Clinical Center, Medical University of Silesia, 40-055 Katowice, Poland
- Department of Ophthalmology, Faculty of Medical Sciences in Katowice, Medical University of Silesia, 40-514 Katowice, Poland
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Yin XF, Wu MH, Jin CJ, Zhou SY. Comparison of photodynamic therapy with two different parameters combined with subconjunctival injection of bevacizumab for corneal neovascularization. Photodiagnosis Photodyn Ther 2024; 46:104067. [PMID: 38548042 DOI: 10.1016/j.pdpdt.2024.104067] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2024] [Revised: 03/22/2024] [Accepted: 03/25/2024] [Indexed: 04/05/2024]
Abstract
BACKGROUND To the best of our knowledge, no studies have been performed to determine the optimal parameters of photodynamic therapy (PDT) combined with subconjunctival injection of bevacizumab for corneal neovascularization. This study aimed to compare the effect of photodynamic therapy with two different sets of parameters combined with subconjunctival injection of bevacizumab for corneal neovascularization. METHODS Patients with stable corneal neovascularization (CNV) unresponsive to conventional treatment (topical steroid) were included in this study. Patients were divided into two groups, receiving PDT with two different sets of parameters (group 1 receiving fluence of 50 J/cm2 at 15 min after intravenous injection of verteporfin with, group 2 receiving fluence of 150 J/cm2 at 60 min after intravenous injection of verteporfin with). Subconjunctival injection of bevacizumab was performed immediately after PDT. All patients were followed for 6 months. Best-corrected visual acuity and intraocular pressure were evaluated, and slit-lamp biomicroscopy as well as digital photography were performed. Average diameter and cumulative length of corneal neovascular were measured to evaluate the corneal neovascularization. RESULTS Seventeen patients (20 eyes) were included in this study. At the last visit, the vision was improved in 12 eyes (60 %), steady in 4 eyes (20 %) and worsen in 4 eyes (20 %). The intraocular pressure (IOP) of all patients remained in normal range. A significant decrease in corneal neovascularization was showed in all the eyes after treatment. At 6 months after the combined treatment, the average diameter and cumulative length of vessels significantly decreased to 0.041 ± 0.023 mm (P < 0.05) and 18.78 ± 17.73 mm (P < 0.05), respectively, compared with the pretreatment data (0.062 ± 0.015 mm, 31.48 ± 18.21 mm). The reduction was more remarkable in group 2 compared to group 1.In group 1, the average diameter was 0.062 ± 0.013mm before and 0.056 ± 0.017mm after, the cumulative length of vessels was 38.66 ± 22.55mm before and 31.21 ± 17.30 after. In group 2, the date were 0.061 ± 0.016mm before and 0.029 ± 0.020mm after, 25.60 ± 8.95 mm before and 8.61 ± 8.26 mm. The reported complications included epithelial defect in four eyes, small white filaments in two eyes and corneal epithelial erosion in two eyes. CONCLUSION The PDT combined with subconjunctival injection of bevacizumab was effective for the chronic corneal neovascularization. A more promising treatment outcome was observed when PDT was performed at 60 min after intravenous injection of verteporfin with fluence of 150 J/cm2. No serious complications or systemic events were observed throughout the follow-up period.
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Affiliation(s)
- Xiao-Fang Yin
- Institute of Ophthalmology, Foshan Hospital Affiliated to Southern Medical University, The Second People's Hospital of Foshan, Foshan 528000, China
| | - Min-Hui Wu
- Institute of Ophthalmology, Foshan Hospital Affiliated to Southern Medical University, The Second People's Hospital of Foshan, Foshan 528000, China
| | - Chen-Jin Jin
- The State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center at Sun Yat-sen University, Guangzhou 510060, China
| | - Shi-You Zhou
- The State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center at Sun Yat-sen University, Guangzhou 510060, China.
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Peng WY, He LW, Yin XF, Zhou BB, Zhou T, Zhou SY. Successful regression of newly formed corneal neovascularization by subconjunctival injection of bevacizumab in patients with chemical burns. Front Med (Lausanne) 2023; 10:1210765. [PMID: 37425330 PMCID: PMC10324651 DOI: 10.3389/fmed.2023.1210765] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2023] [Accepted: 06/05/2023] [Indexed: 07/11/2023] Open
Abstract
Purpose To investigate the effect and timing of subconjunctival bevacizumab injection on inhibiting corneal neovascularization (CorNV) in patients after chemical burns. Methods Patients with CorNV secondary to chemical burns were involved. Two subconjunctival injections of bevacizumab (2.5 mg/0.1 mL per involved quadrant) with an interval of 4 weeks were administered, and followed up a year. The area occupied by neovascular vessels (NA), accumulative neovascular length (NL), mean neovascular diameter (ND), best-corrected visual acuity (BCVA) and intraocular pressure (IOP) were evaluated. Complication was also recorded. Results Eleven patients with CorNV were involved. Eight patients had a history of surgery (four had amniotic grafts, one had keratoplasty, and three had amniotic grafts and keratoplasty). Decreasing in NA, NL, and ND were statistically significant at each time point compared to the baseline (p < 0.01). CorNV that developed within 1 month was considerably regressed, and vessels with fibrovascular membranes were found to be narrower and shorter than pretreatment. BCVA improved in five patients (from one to five lines), remained unchanged in five patients, and decreased in one patient compared to pretreatment. Conclusion Subconjunctival bevacizumab injection has a particular potential for the regression of CorNV, especially newly formed within 1 month in patients after chemical burns.
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Affiliation(s)
- Wen-yan Peng
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangdong Provincial Key Laboratory of Ophthalmology and Visual Science, Guangdong Provincial Clinical Research Center for Ocular Diseases, Guangzhou, China
| | - Li-wen He
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangdong Provincial Key Laboratory of Ophthalmology and Visual Science, Guangdong Provincial Clinical Research Center for Ocular Diseases, Guangzhou, China
| | - Xiao-fang Yin
- Department of Ophthalmology, The Second People's Hospital of Foshan, Foshan, China
| | - Bin-Bing Zhou
- Department of Ophthalmology, The Affiliated First Hospital of Guangdong Pharmaceutical University, Guangzhou, China
| | - Tao Zhou
- Department of Ophthalmology, First People’s Hospital of Guiyang, Guiyang, China
| | - Shi-you Zhou
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangdong Provincial Key Laboratory of Ophthalmology and Visual Science, Guangdong Provincial Clinical Research Center for Ocular Diseases, Guangzhou, China
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Ocular Drug Delivery: Advancements and Innovations. Pharmaceutics 2022; 14:pharmaceutics14091931. [PMID: 36145679 PMCID: PMC9506479 DOI: 10.3390/pharmaceutics14091931] [Citation(s) in RCA: 15] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2022] [Revised: 08/24/2022] [Accepted: 09/06/2022] [Indexed: 11/16/2022] Open
Abstract
Ocular drug delivery has been significantly advanced for not only pharmaceutical compounds, such as steroids, nonsteroidal anti-inflammatory drugs, immune modulators, antibiotics, and so forth, but also for the rapidly progressed gene therapy products. For conventional non-gene therapy drugs, appropriate surgical approaches and releasing systems are the main deliberation to achieve adequate treatment outcomes, whereas the scope of “drug delivery” for gene therapy drugs further expands to transgene construct optimization, vector selection, and vector engineering. The eye is the particularly well-suited organ as the gene therapy target, owing to multiple advantages. In this review, we will delve into three main aspects of ocular drug delivery for both conventional drugs and adeno-associated virus (AAV)-based gene therapy products: (1) the development of AAV vector systems for ocular gene therapy, (2) the innovative carriers of medication, and (3) administration routes progression.
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Ben-Arzi A, Ehrlich R, Neumann R. Retinal Diseases: The Next Frontier in Pharmacodelivery. Pharmaceutics 2022; 14:pharmaceutics14050904. [PMID: 35631490 PMCID: PMC9143814 DOI: 10.3390/pharmaceutics14050904] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2022] [Revised: 04/03/2022] [Accepted: 04/16/2022] [Indexed: 02/04/2023] Open
Abstract
The future continuous growth of the global older population augments the burden of retinal diseases worldwide. Retinal characteristics isolating and protecting the sensitive neuro-retina from the rest of the ocular tissues challenge drug delivery and promote research and development toward new horizons. In this review, we wish to describe the unmet medical needs, discuss the novel modes of delivery, and disclose to the reader a spectrum of older-to-novel drug delivery technologies, innovations, and the frontier of pharmacodelivery to the retina. Treating the main retinal diseases in the everlasting war against blindness and its associated morbidity has been growing steadily over the last two decades. Implants, new angiogenesis inhibitor agents, micro- and nano-carriers, and the anchored port delivery system are becoming new tools in this war. The revolution and evolution of new delivery methods might be just a few steps ahead, yet its assimilation in our daily clinical work may take time, due to medical, economical, and regulatory elements that need to be met in order to allow successful development and market utilization of new technologies. Therefore, further work is warranted, as detailed in this Pharmaceutics Special Issue.
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Affiliation(s)
- Assaf Ben-Arzi
- Department of Ophthalmology, Rabin Medical Center, 39 Jabotinski St., Petah Tikva 4941492, Israel; (A.B.-A.); (R.E.)
- Sackler School of Medicine, Tel Aviv University, P.O. Box 39040, Tel Aviv 6997801, Israel
| | - Rita Ehrlich
- Department of Ophthalmology, Rabin Medical Center, 39 Jabotinski St., Petah Tikva 4941492, Israel; (A.B.-A.); (R.E.)
- Sackler School of Medicine, Tel Aviv University, P.O. Box 39040, Tel Aviv 6997801, Israel
| | - Ron Neumann
- Department of Ophthalmology, Maccabi Sherutei Briut, Ramat Hasharon 4731001, Israel
- Correspondence:
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Ocular Drug Delivery to the Retina: Current Innovations and Future Perspectives. Pharmaceutics 2021; 13:pharmaceutics13010108. [PMID: 33467779 PMCID: PMC7830424 DOI: 10.3390/pharmaceutics13010108] [Citation(s) in RCA: 74] [Impact Index Per Article: 24.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/25/2020] [Revised: 01/13/2021] [Accepted: 01/13/2021] [Indexed: 12/12/2022] Open
Abstract
Treatment options for retinal diseases, such as neovascular age-related macular degeneration, diabetic retinopathy, and retinal vascular disorders, have markedly expanded following the development of anti-vascular endothelial growth factor intravitreal injection methods. However, because intravitreal treatment requires monthly or bimonthly repeat injections to achieve optimal efficacy, recent investigations have focused on extended drug delivery systems to lengthen the treatment intervals in the long term. Dose escalation and increasing molecular weight of drugs, intravitreal implants and nanoparticles, hydrogels, combined systems, and port delivery systems are presently under preclinical and clinical investigations. In addition, less invasive techniques rather than intravitreal administration routes, such as topical, subconjunctival, suprachoroidal, subretinal, and trans-scleral, have been evaluated to reduce the treatment burden. Despite the latest advancements in the field of ophthalmic pharmacology, enhancing drug efficacy with high ocular bioavailability while avoiding systemic and local adverse effects is quite challenging. Consequently, despite the performance of numerous in vitro studies, only a few techniques have translated to clinical trials. This review discusses the recent developments in ocular drug delivery to the retina, the pharmacokinetics of intravitreal drugs, efforts to extend drug efficacy in the intraocular space, minimally invasive techniques for drug delivery to the retina, and future perspectives in this field.
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Kasuya Y, Sano I, Makino S. Interstitial Keratitis with Lipid Keratopathy Mimicking Corneal Opacity Induced by Brimonidine Tartrate Eye Drops. Klin Monbl Augenheilkd 2020; 237:1466-1467. [PMID: 33285590 DOI: 10.1055/a-1265-7105] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
Affiliation(s)
- Yuka Kasuya
- Ophthalmology, Jichi Medical University, Shimotsuke, Japan
| | - Ichiya Sano
- Ophthalmology, Jichi Medical University, Shimotsuke, Japan
| | - Shinji Makino
- Ophthalmology, Jichi Medical University, Shimotsuke, Japan
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Hall MN, Moshirfar M, Amin-Javaheri A, Ouano DP, Ronquillo Y, Hoopes PC. Lipid Keratopathy: A Review of Pathophysiology, Differential Diagnosis, and Management. Ophthalmol Ther 2020; 9:833-852. [PMID: 33058067 PMCID: PMC7708541 DOI: 10.1007/s40123-020-00309-y] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2020] [Accepted: 09/28/2020] [Indexed: 12/11/2022] Open
Abstract
Lipid keratopathy is a disease in which fat deposits accumulate in the cornea, leading to opacification and decrease of visual acuity. This condition can be idiopathic without signs of previous corneal disease or secondary to ocular or systemic diseases. Lipid keratopathy is usually associated with abnormal vascularization of the cornea, and the lipid classically deposits adjacent to these vessels. Treatment of this condition usually aims to eliminate or prevent abnormal vessel formation, and several modalities have been described. In this review we summarize the etiology, pathophysiology, and clinical presentation of lipid keratopathy and describe current and emerging treatment regimens.
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Affiliation(s)
- MacGregor N Hall
- McGovern Medical School, The University of Texas Health Science Center at Houston, Houston, TX, USA
| | - Majid Moshirfar
- Hoopes Vision Research Center, Hoopes Vision, Draper, UT, USA.
- Department of Ophthalmology and Visual Sciences, John A. Moran Eye Center, University of Utah School of Medicine, Salt Lake City, UT, USA.
- Utah Lions Eye Bank, Murray, UT, USA.
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Sustained subconjunctival drug delivery systems: current trends and future perspectives. Int Ophthalmol 2020; 40:2385-2401. [DOI: 10.1007/s10792-020-01391-8] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2019] [Accepted: 04/15/2020] [Indexed: 12/17/2022]
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Human antigen R protein modulates vascular endothelial growth factor expression in human corneal epithelial cells under hypoxia. J Formos Med Assoc 2019; 119:359-366. [PMID: 31262614 DOI: 10.1016/j.jfma.2019.06.006] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2019] [Revised: 05/20/2019] [Accepted: 06/14/2019] [Indexed: 01/23/2023] Open
Abstract
PURPOSE Corneal avascularity is critical for corneal transparency; therefore, a tailored process has been presumed to minimize corneal neovascularization (NV). In most cell types, the transcription of vascular endothelial growth factor (VEGF) is up-regulated, and the stability of VEGF mRNA is sustained by human antigen R (HuR) during hypoxia; however, whether such response applies to corneal epithelial cells is unclear. METHODS Human corneal epithelial cells (HCECs) and MCF-7 cells that serves as the control were incubated under 0.5% oxygen, and the levels of VEGF and HuR were examined time-dependently. The alteration of HuR was also examined in vivo using the closed-eye contact lens-induced corneal neovascularization rabbit model and immunohistochemistry. Additionally, the expression of HuR was modulated by transfection of plasmids encoding HuR or siRNA targeting HuR to validate the role of HuR in VEGF expression. RESULTS We found that, unlike in control cells, the level of VEGF was not up-regulated, and the HuR expression was declined in HCECs following hypoxia. The HuR immunostaining intensities were decreased in corneal epithelial cells of rabbits wearing contact lenses. In addition, HuR overexpression restored the ability of HCECs to up-regulate VEGF under hypoxia; however, knockdown of HuR suppressed hypoxia-induced VEGF in control cells but did not further decrease VEGF in HCECs. These findings suggest that HCECs may modulate HuR to suppress hypoxia-mediated up-regulation of VEGF. CONCLUSION Our study revealed a distinct regulation of VEGF via HuR in HCECs following hypoxia, which likely contributes to minimizing corneal NV and/or maintenance of corneal avascularity.
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Roshandel D, Eslani M, Baradaran-Rafii A, Cheung AY, Kurji K, Jabbehdari S, Maiz A, Jalali S, Djalilian AR, Holland EJ. Current and emerging therapies for corneal neovascularization. Ocul Surf 2018; 16:398-414. [PMID: 29908870 DOI: 10.1016/j.jtos.2018.06.004] [Citation(s) in RCA: 123] [Impact Index Per Article: 20.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2018] [Revised: 06/10/2018] [Accepted: 06/12/2018] [Indexed: 02/08/2023]
Abstract
The cornea is unique because of its complete avascularity. Corneal neovascularization (CNV) can result from a variety of etiologies including contact lens wear; corneal infections; and ocular surface diseases due to inflammation, chemical injury, and limbal stem cell deficiency. Management is focused primarily on the etiology and pathophysiology causing the CNV and involves medical and surgical options. Because inflammation is a key factor in the pathophysiology of CNV, corticosteroids and other anti-inflammatory medications remain the mainstay of treatment. Anti-VEGF therapies are gaining popularity to prevent CNV in a number of etiologies. Surgical options including vessel occlusion and ocular surface reconstruction are other options depending on etiology and response to medical therapy. Future therapies should provide more effective treatment options for the management of CNV.
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Affiliation(s)
- Danial Roshandel
- Ocular Tissue Engineering Research Center, Shahid Beheshti University of Medical Sciences, Tehran, Iran
| | - Medi Eslani
- Department of Ophthalmology and Visual Sciences, University of Illinois at Chicago, Chicago, IL, USA; Cincinnati Eye Institute, Edgewood, KY/ University of Cincinnati, Department of Ophthalmology, Cincinnati, OH, USA
| | - Alireza Baradaran-Rafii
- Ocular Tissue Engineering Research Center, Shahid Beheshti University of Medical Sciences, Tehran, Iran
| | - Albert Y Cheung
- Cincinnati Eye Institute, Edgewood, KY/ University of Cincinnati, Department of Ophthalmology, Cincinnati, OH, USA
| | - Khaliq Kurji
- Cincinnati Eye Institute, Edgewood, KY/ University of Cincinnati, Department of Ophthalmology, Cincinnati, OH, USA
| | - Sayena Jabbehdari
- Ocular Tissue Engineering Research Center, Shahid Beheshti University of Medical Sciences, Tehran, Iran; Department of Ophthalmology and Visual Sciences, University of Illinois at Chicago, Chicago, IL, USA
| | - Alejandra Maiz
- Department of Ophthalmology and Visual Sciences, University of Illinois at Chicago, Chicago, IL, USA
| | - Setareh Jalali
- Ocular Tissue Engineering Research Center, Shahid Beheshti University of Medical Sciences, Tehran, Iran
| | - Ali R Djalilian
- Department of Ophthalmology and Visual Sciences, University of Illinois at Chicago, Chicago, IL, USA.
| | - Edward J Holland
- Cincinnati Eye Institute, Edgewood, KY/ University of Cincinnati, Department of Ophthalmology, Cincinnati, OH, USA.
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Comparison of the Effects of Subconjunctival Injections of Bevacizumab and Interferon Alpha-2a on Corneal Angiogenesis in a Rat Model. MEDICINA-LITHUANIA 2018; 54:medicina54020016. [PMID: 30344247 PMCID: PMC6037251 DOI: 10.3390/medicina54020016] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/21/2018] [Revised: 04/09/2018] [Accepted: 04/13/2018] [Indexed: 11/16/2022]
Abstract
Background and objective: Corneal neovascularization (CNV) is a vision-threatening condition arising from various corneal diseases. The aim of this study is to compare the effectiveness of bevacizumab and interferon alpha-2a (IFNα-2a) treatment on corneal neovascularization. Materials and Methods: Twenty-four Wistar albino rats were used in this study. After cauterization of the cornea with a silver nitrate applicator stick, the control group received 0.1 mL saline solution, the second group received 0.1 mL IFNα-2a (IFNα-2a, 6 million international units [MIU]/0.5 mL), and the third group received 2.5 mg bevacizumab by subconjunctival injection. An additional injection was administered to each group on the fourth day. After one week, the corneal neovascularization rate and the longest neovascular sprout length were determined. Results: The neovascularization rate (saline 0.65 ± 0.05; IFNα-2a 0.62 ± 0.07; bevacizumab 0.42 ± 0.11) with bevacizumab was significantly lower, more than those with IFNα-2a and saline (p < 0.001 and p < 0.001). The longest neovascular sprout length (saline, 4.00 ± 0.6 mm; IFNα-2a, 3.63 ± 0.52 mm; bevacizumab, 2.81 ± 0.65 mm) with bevacizumab was significantly shorter than those with saline and IFNα-2a (p = 0.001 and p = 0.012). Conclusions: Subconjunctival IFNα-2a has limited efficacy in the treatment of corneal neovascularization.
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In Vivo Confocal Microscopic Study of Hard Contact Lens-Induced Lipid Keratopathy Secondary to Corneal Neovascularization in a Rabbit Hypercholesterolemic Model. Eye Contact Lens 2018; 44 Suppl 2:S325-S332. [PMID: 29489496 DOI: 10.1097/icl.0000000000000494] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
OBJECTIVES In vivo confocal microscopy was used to observe the morphological presentations and anatomical correlations between corneal neovascularization (NV) and intracorneal lipid deposition in a rabbit model of contact lens (CL)-induced lipid keratopathy secondary to corneal NV. METHODS Rabbits were divided into 3 groups: (1) 8-week normal diet, (2) 8-week high-cholesterol diet, and (3) 4-week normal diet followed by 4-week high-cholesterol diet. Corneal NV was induced by closed-eye CL. The formation and maturation of corneal NV were shown by immunohistochemical staining against CD31 and high-molecular-weight melanoma-associated antigen. In vivo confocal microscopy identified corneal NV and lipid deposition. Acquired images for each eye were arranged and mapped into subconfluent montages. RESULTS In group 1, corneal NV sprouting formed from the peripheral to the central cornea by the end of week 4. Pericytes around vessels were shown after 2 weeks of CL wear. In group 2, lipid deposition started from the peripheral cornea and progressively covered the whole cornea. In group 3, lipid deposition was found first in the central cornea after 2 weeks of high-cholesterol diet and progressed to cover the peripheral cornea. In vivo confocal microscopy demonstrated four different patterns of intracorneal lipid deposition: spindle shapes arranged randomly or in parallel, amorphous shapes, multiangular shapes, and mixed types. Intracorneal lipid deposition was distributed from basal corneal epithelium to deep stroma. CONCLUSIONS Intracorneal lipids tend to accumulate around newly formed corneal NV but can extend to the area covered with mature NV. In vivo confocal microscopy can demonstrate various shapes and depths of intracorneal lipid deposition.
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Feizi S, Azari AA, Safapour S. Therapeutic approaches for corneal neovascularization. EYE AND VISION 2017; 4:28. [PMID: 29234686 PMCID: PMC5723406 DOI: 10.1186/s40662-017-0094-6] [Citation(s) in RCA: 78] [Impact Index Per Article: 11.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/14/2017] [Accepted: 11/26/2017] [Indexed: 02/07/2023]
Abstract
Angiogenesis refers to new blood vessels that originate from pre-existing vascular structures. Corneal neovascularization which can lead to compromised visual acuity occurs in a wide variety of corneal pathologies. A large subset of measures has been advocated to prevent and/or treat corneal neovascularization with varying degrees of success. These approaches include topical corticosteroid administration, laser treatment, cautery, and fine needle diathermy. Since the imbalance between proangiogenic agents and antiangiogenic agents primarily mediate the process of corneal neovascularization, recent therapies are intended to disrupt the different steps in the synthesis and actions of proangiogenic factors. These approaches, however, are only partially effective and may lead to several side effects. The aim of this article is to review the most relevant treatments for corneal neovascularization available so far.
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Affiliation(s)
- Sepehr Feizi
- Ophthalmic Research Center, Labbafinejad Medical Center, Shahid Beheshti University of Medical Sciences, Tehran, 16666 Iran
| | - Amir A Azari
- Ophthalmic Research Center, Labbafinejad Medical Center, Shahid Beheshti University of Medical Sciences, Tehran, 16666 Iran
| | - Sharareh Safapour
- Ophthalmic Research Center, Labbafinejad Medical Center, Shahid Beheshti University of Medical Sciences, Tehran, 16666 Iran
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Immunologic Rejection Episodes After Deep Anterior Lamellar Keratoplasty: Incidence and Risk Factors. Cornea 2017; 36:1076-1082. [DOI: 10.1097/ico.0000000000001223] [Citation(s) in RCA: 36] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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Al-Debasi T, Al-Bekairy A, Al-Katheri A, Al Harbi S, Mansour M. Topical versus subconjunctival anti-vascular endothelial growth factor therapy (Bevacizumab, Ranibizumab and Aflibercept) for treatment of corneal neovascularization. Saudi J Ophthalmol 2017; 31:99-105. [PMID: 28559722 PMCID: PMC5436388 DOI: 10.1016/j.sjopt.2017.02.008] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2015] [Accepted: 02/28/2017] [Indexed: 12/01/2022] Open
Abstract
In order to evaluate the effect of topical and subconjunctival anti-vascular endothelial growth factor (anti-VEGF) therapy, Ranibizumab, Bevacizumab and Aflibercept as a therapy for corneal neovascularization (NV) treatment, the aim of this study was to review all data related to some of anti-VEGF as a promising therapies for corneal NV treatment. Corneal NV is a dangerous condition leading to a marked reduction in vision due to angiogenesis of abnormal vessels that block light. During the recent years, we have recognized new drug proliferation for corneal NV treatment. Recently, anti-VEGF therapies are one of the most important drugs used for corneal NV treatment. Several growth factors are involved in angiogenesis. The most important growth factor in corneal angiogenesis is VEGF. VEGF can be considered as key mediators in corneal angiogenesis. It is upregulated during corneal NV. In fact, anti-VEGF therapies have shown efficacy in attenuation of corneal NV in both animal models and clinical trials. A promising therapeutic success has been achieved using antibodies directed against VEGF. Bevacizumab has demonstrated efficacy and efficiency in the treatment of different neo-vascular ocular diseases and it has partially reduced corneal NV through different routes of administrations: topical, subconjunctival, and intraocular application. A similar efficacy to bevacizumab profiles in the treatment of neo-vascular age-related macular degeneration was induced by ranibizumab. Moreover, at worse levels of initial visual acuity of diabetic macular edema, aflibercept was more effective at improving vision. Anti-VEGF agents (Bevacizumab, Ranibizumab and Aflibercept) seem to have a higher efficiency and efficacy for corneal NV treatment. Both subconjunctival therapy and topical therapy of bevacizumab prohibit corneal NV, while early treatment with subconjunctival administration of ranibizumab may successfully reduce corneal NV. Therefore, establishment of safe doses is highly important before these drugs can be involved in the clinical setting. Further investigations and studies are highly warranted to adjust the dose and route of administration for the antibodies directed against VEGF to be the key therapeutic agents in the corneal NV treatment.
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Affiliation(s)
- Tariq Al-Debasi
- Division of Ophthalmology, King Abdulaziz Medical City-Riyadh, MC 1445, Saudi Arabia
| | - Abdulkareem Al-Bekairy
- Pharmaceutical Care Services, King Abdulaziz Medical City-Riyadh, MC 1445, Saudi Arabia.,Department of Pharmacy Practice and Pharmaceutical Sciences, College of Pharmacy, King Saud bin Abdulaziz University for Health Sciences, P.O Box 3660, Riyadh 11426, Saudi Arabia
| | - Abdulmalik Al-Katheri
- Pharmaceutical Care Services, King Abdulaziz Medical City-Riyadh, MC 1445, Saudi Arabia.,Department of Pharmacy Practice and Pharmaceutical Sciences, College of Pharmacy, King Saud bin Abdulaziz University for Health Sciences, P.O Box 3660, Riyadh 11426, Saudi Arabia
| | - Shmeylan Al Harbi
- Pharmaceutical Care Services, King Abdulaziz Medical City-Riyadh, MC 1445, Saudi Arabia.,Department of Pharmacy Practice and Pharmaceutical Sciences, College of Pharmacy, King Saud bin Abdulaziz University for Health Sciences, P.O Box 3660, Riyadh 11426, Saudi Arabia
| | - Mahmoud Mansour
- Department of Pharmacy Practice and Pharmaceutical Sciences, College of Pharmacy, King Saud bin Abdulaziz University for Health Sciences, P.O Box 3660, Riyadh 11426, Saudi Arabia
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Eun JS, Cho KJ. Two Cases of Corneal Neovascularization Improved by Electrocauterization and Subconjunctival Bevacizumab Injection. JOURNAL OF THE KOREAN OPHTHALMOLOGICAL SOCIETY 2017. [DOI: 10.3341/jkos.2017.58.8.981] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Affiliation(s)
- Jun Soo Eun
- Department of Ophthalmology, Dankook University College of Medicine, Cheonan, Korea
| | - Kyong Jin Cho
- Department of Ophthalmology, Dankook University College of Medicine, Cheonan, Korea
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Subbotin VM. Excessive intimal hyperplasia in human coronary arteries before intimal lipid depositions is the initiation of coronary atherosclerosis and constitutes a therapeutic target. Drug Discov Today 2016; 21:1578-1595. [DOI: 10.1016/j.drudis.2016.05.017] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2016] [Revised: 04/29/2016] [Accepted: 05/25/2016] [Indexed: 12/19/2022]
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Kim S, Oh J, Kim K. Morphologic Changes in Patient with Drusen and Drusenoid Pigment Epithelial Detachment after Intravitreal Ranibizumab for Choroidal Neovascular Membrane : A Case Report. Open Ophthalmol J 2016; 10:1-4. [PMID: 27014379 PMCID: PMC4780511 DOI: 10.2174/1874364101610010001] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2015] [Revised: 10/30/2015] [Accepted: 10/30/2015] [Indexed: 11/22/2022] Open
Abstract
The authors present a case of morphologic changes of drusen and drusenoid pigment epithelial detachment (DPED) after treating choroidal neovascularization (CNV) using ranibizumab in age-related macular degeneration (AMD). A 71-year-old woman has noticed mild visual acuity deterioration in the right eye for several months. She was presented with some drusen and DPED associated with CNV. This patient was given intravitreal injection of 0.5 mg of ranibizumab five times at monthly intervals for treating CNV. DPED in the temporal and drusen in the superior to macula were diminished, which continued up to 2 months. Intravitreal ranibizumab injection may have influenced with diminishment of drusen and DPED. After 2 months, CNV was recurred.
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Affiliation(s)
- Sukjin Kim
- Department of Ophthalmology, Saevit Eye Hospital, Goyangsi, Korea
| | - Jeongjae Oh
- Department of Ophthalmology, Saevit Eye Hospital, Goyangsi, Korea
| | - Kiseok Kim
- Department of Ophthalmology, Saevit Eye Hospital, Goyangsi, Korea
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Transplantation of PEDF-transfected pigment epithelial cells inhibits corneal neovascularization in a rabbit model. Graefes Arch Clin Exp Ophthalmol 2015; 253:1061-9. [DOI: 10.1007/s00417-015-2954-x] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2014] [Revised: 01/19/2015] [Accepted: 01/26/2015] [Indexed: 02/05/2023] Open
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Uso de terapia antifactor de crecimiento vascular endotelial en patología corneal. REVISTA MEXICANA DE OFTALMOLOGÍA 2014. [DOI: 10.1016/j.mexoft.2014.03.005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
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Mechanisms controlling the effects of bevacizumab (avastin) on the inhibition of early but not late formed corneal neovascularization. PLoS One 2014; 9:e94205. [PMID: 24714670 PMCID: PMC3979754 DOI: 10.1371/journal.pone.0094205] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2013] [Accepted: 03/13/2014] [Indexed: 11/29/2022] Open
Abstract
Purpose To evaluate the effects and underlying mechanisms of early and late subconjunctival injection of bevacizumab on the inhibition of corneal neovascularization (NV). Methods Corneal NV was induced by closed eye contact lens wear followed by a silk suture tarsorrhaphy in rabbits. Weekly subconjunctival injections of bevacizumab (5.0 mg) for 1 month were started immediately (early treatment group) or 1 month after induction of corneal NV with continuous induction (late treatment group). The severity of corneal NV was evaluated. Immunostaining was used to evaluate the intracorneal diffusion of bevacizumab, and the existence of pericytes and smooth muscle cells around the NV. The expression of AM-3K, an anti-macrophage antibody, vascular endothelial growth factor (VEGF) with its receptors (VEGFR1 and VEGFR2), and vascular endothelial apoptosis were also evaluated. Western blot analysis was performed to quantify the expression level of VEGF, VEGFR1 and VEGFR2 on corneal epithelium and stroma in different groups. Results Early treatment with bevacizumab inhibited corneal NV more significantly than late treatment. Intracorneal diffusion of bevacizumab was not different among different groups. Immunostaining showed pericytes and smooth muscle cells around newly formed vessels as early as 2 weeks after induction. Immunostaining and Western blot analysis showed that VEGF, VEGFR1, and VEGFR2 on corneal stroma increased significantly in no treatment groups and late treatment groups, but not in early treatment group. Bevacizumab significantly inhibited macrophage infiltration in the early but not late treatment group. Sporadic vascular endothelial apoptosis was found at 4 weeks in the late but not early treatment group. Conclusions Early but not late injection of bevacizumab inhibited corneal NV. Late injection of bevacizumab did not alter macrophage infiltration, and can't inhibit the expression of VEGF, VEGFR1, and VEGFR2 on corneal vessels. The inhibition of corneal NV in early treatment group does not occur via vascular endothelial apoptosis.
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Recurrence of corneal neovascularization associated with lipid deposition after subconjunctival injection of bevacizumab. Cornea 2014; 32:1446-53. [PMID: 24055900 DOI: 10.1097/ico.0b013e31825ec407] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
PURPOSE To report 7 cases of recurrent corneal neovascularization (NV) and lipid deposition after subconjunctival injection of bevacizumab for the treatment of corneal NV-induced lipid keratopathy. METHODS We conducted a prospective interventional case series that included 20 eyes of chronic lipid keratopathy that received bevacizumab injection for the treatment of corneal NV and lipid deposition, including 7 eyes with recurrent corneal NV and lipid deposition after ceasing treatment. Repeated subconjunctival injections of bevacizumab were performed in 5 patients with recurrence. Penetrating keratoplasty was performed in 1 patient who had severely recurrent lipid deposition. Clinical presentation of corneal NV and lipid deposition, best-corrected visual acuity, and complications after treatments were recorded. RESULTS Bevacizumab inhibited corneal NV and lipid depositions in 19 patients. Seven of the 20 patients (35%) had different patterns of recurrence of corneal NV/lipid deposition 6 to 15 months after discontinuing treatment. Five of the 7 patients in whom corneal NV/lipid deposition was recurrent received another course of repeated bevacizumab treatments. Three eyes had partial response to the second course of treatment. Two eyes had too short re-treatment course to have conclusions. One patient who received penetrating keratoplasty had successful result after surgery. CONCLUSIONS Corneal NV and lipid deposition may recur after ceasing the subconjunctival bevacizumab injections for lipid keratopathy. Some patients respond at least partially to repeated injections.
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Ryoo NK, Lee EJ, Kim TW. Regression of iris neovascularization after subconjunctival injection of bevacizumab. KOREAN JOURNAL OF OPHTHALMOLOGY 2013; 27:299-303. [PMID: 23908579 PMCID: PMC3730075 DOI: 10.3341/kjo.2013.27.4.299] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2011] [Accepted: 11/30/2011] [Indexed: 11/25/2022] Open
Abstract
To describe three cases of neovascular glaucoma (NVG) where iris or angle neovascularization regressed remarkably after subconjunctival bevacizumab injections used as the initial treatment before pan retinal photocoagulation (PRP) and/or filtering surgery. Three consecutive NVG patients whose intraocular pressure (IOP) was not controlled with maximal medication were offered an off-label subconjunctival injection of bevacizumab (2.5-3.75 mg/0.1-0.15 mL, Avastin). Bevacizumab was injected into the subconjunctival space close to the corneal limbus in two or three quadrants using a 26-gauge needle. Serial anterior segment photographs were taken before and after the injection. Following subconjunctival injection of bevacizumab, iris or angle neovascularization regressed rapidly within several days. Such regression was accompanied by lowering of IOP in all three cases. The patients underwent subsequent PRP and/or filtering surgery, and the IOP was further stabilized. Our cases demonstrate that subconjunctival bevacizumab injection can be potentially useful as an initial treatment in NVG patients before laser or surgical treatment.
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Affiliation(s)
- Na Kyung Ryoo
- Department of Ophthalmology, Seoul National University Hospital, Seoul, Korea
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Abstract
PURPOSE OF REVIEW A significant recent advancement in the treatment of neovascularization of the anterior segment of the eye is the development of antivascular endothelial growth factor (anti-VEGF) therapeutic agents.We present a review of the current knowledge on anti-VEGF therapy with bevacizumab for anterior segment neovascularization. RECENT FINDINGS A review of the recent peer-reviewed literature reveals an increasing number of experimental and clinical studies on the use of Avastin in both human and animal eye models. Although the numbers are still relatively small, the evidence suggests that bevacizumab may be effective in the treatment of corneal and iris neovascularization. Its effect on primary and recurrent pterygium is more controversial. In general, achievement of vessels regression is usually partial, and recurrence may occur after cessation of treatment. Response to treatment is affected by the chronicity of vessels, their extent, the cause for blood vessels formation, and the route of administration. SUMMARY Effective short-term response together with high patient tolerance to local bevacizumab therapy offer encouraging results for the management of anterior segment neovascular disorders. Although statistically significant regression of vessels has been documented in many studies, the clinical significance of this finding is still a subject of debate.
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Chang JH, Garg NK, Lunde E, Han KY, Jain S, Azar DT. Corneal neovascularization: an anti-VEGF therapy review. Surv Ophthalmol 2012; 57:415-29. [PMID: 22898649 DOI: 10.1016/j.survophthal.2012.01.007] [Citation(s) in RCA: 261] [Impact Index Per Article: 21.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2011] [Revised: 01/14/2012] [Accepted: 01/16/2012] [Indexed: 01/02/2023]
Abstract
Corneal neovascularization is a serious condition that can lead to a profound decline in vision. The abnormal vessels block light, cause corneal scarring, compromise visual acuity, and may lead to inflammation and edema. Corneal neovascularization occurs when the balance between angiogenic and antiangiogenic factors is tipped toward angiogenic molecules. Vascular endothelial growth factor (VEGF), one of the most important mediators of angiogenesis, is upregulated during neovascularization. In fact, anti-VEGF agents have efficacy in the treatment of neovascular age-related macular degeneration, diabetic retinopathy, macular edema, neovascular glaucoma, and other neovascular diseases. These same agents have great potential for the treatment of corneal neovascularization. We review some of the most promising anti-VEGF therapies, including bevacizumab, VEGF trap, siRNA, and tyrosine kinase inhibitors.
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Affiliation(s)
- Jin-Hong Chang
- Department of Ophthalmology and Visual Sciences, Illinois Eye and Ear Infirmary, University of Illinois at Chicago, Chicago 60612, USA.
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Triple therapy for corneal neovascularization: a case report. Eur J Ophthalmol 2012; 22 Suppl 7:S126-8. [PMID: 21928258 DOI: 10.5301/ejo.5000050] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/14/2011] [Indexed: 11/20/2022]
Abstract
PURPOSE To investigate the effect of the combination of photodynamic therapy with verteporfin and subconjunctival bevacizumab and triamcinolone acetonide on corneal neovascularization secondary to corneal graft failure. METHODS A patient with extensive deep and superficial corneal neovascularization underwent same day triple therapy with subconjunctival bevacizumab (1.25 mg), subconjunctival triamcinolone acetonide (40 mg), and photodynamic therapy with verteporfin (fluence 50 J/cm², irradiance 300 mW/cm²). RESULTS A complete angiographic new vessel regression was obtained and was discernible starting 7 days after combination therapy. Three months after treatment, an initial new-vessel sprout was noted. Triple therapy was then repeated. No angiographic evidence of corneal neovascularization was detectable for the entire 6-month follow-up duration. CONCLUSIONS Triple therapy may offer a promising tool in the treatment of corneal neovascularization.
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Subbotin VM. Neovascularization of coronary tunica intima (DIT) is the cause of coronary atherosclerosis. Lipoproteins invade coronary intima via neovascularization from adventitial vasa vasorum, but not from the arterial lumen: a hypothesis. Theor Biol Med Model 2012; 9:11. [PMID: 22490844 PMCID: PMC3492120 DOI: 10.1186/1742-4682-9-11] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2012] [Accepted: 03/18/2012] [Indexed: 01/15/2023] Open
Abstract
BACKGROUND An accepted hypothesis states that coronary atherosclerosis (CA) is initiated by endothelial dysfunction due to inflammation and high levels of LDL-C, followed by deposition of lipids and macrophages from the luminal blood into the arterial intima, resulting in plaque formation. The success of statins in preventing CA promised much for extended protection and effective therapeutics. However, stalled progress in pharmaceutical treatment gives a good reason to review logical properties of the hypothesis underlining our efforts, and to reconsider whether our perception of CA is consistent with facts about the normal and diseased coronary artery. ANALYSIS To begin with, it must be noted that the normal coronary intima is not a single-layer endothelium covering a thin acellular compartment, as claimed in most publications, but always appears as a multi-layer cellular compartment, or diffuse intimal thickening (DIT), in which cells are arranged in many layers. If low density lipoprotein cholesterol (LDL-C) invades the DIT from the coronary lumen, the initial depositions ought to be most proximal to blood, i.e. in the inner DIT. The facts show that the opposite is true, and lipids are initially deposited in the outer DIT. This contradiction is resolved by observing that the normal DIT is always avascular, receiving nutrients by diffusion from the lumen, whereas in CA the outer DIT is always neovascularized from adventitial vasa vasorum. The proteoglycan biglycan, confined to the outer DIT in both normal and diseased coronary arteries, has high binding capacity for LDL-C. However, the normal DIT is avascular and biglycan-LDL-C interactions are prevented by diffusion distance and LDL-C size (20 nm), whereas in CA, biglycan in the outer DIT can extract lipoproteins by direct contact with the blood. These facts lead to the single simplest explanation of all observations: (1) lipid deposition is initially localized in the outer DIT; (2) CA often develops at high blood LDL-C levels; (3) apparent CA can develop at lowered blood LDL-C levels. This mechanism is not unique to the coronary artery: for instance, the normally avascular cornea accumulates lipoproteins after neovascularization, resulting in lipid keratopathy. HYPOTHESIS Neovascularization of the normally avascular coronary DIT by permeable vasculature from the adventitial vasa vasorum is the cause of LDL deposition and CA. DIT enlargement, seen in early CA and aging, causes hypoxia of the outer DIT and induces neovascularization. According to this alternative proposal, coronary atherosclerosis is not related to inflammation and can occur in individuals with normal circulating levels of LDL, consistent with research findings.
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