Author Interviews, Brigham & Women's - Harvard, JAMA, Nutrition, Ophthalmology / 16.01.2016
Dietary Nitrates From Green Leafy Vegetables Linked To Decreased Glaucoma Risk
More on Ophthalmology on MedicalResearch.com
MedicalResearch.com Interview with:
Jae Hee Kang, MSc, SC
Associate Epidemiologist, Brigham and Women's Hospital
Assistant Professor of Medicine, Harvard Medical School
Brigham and Women's Hospital
Department of Medicine
Channing Division of Network Medicine
Boston, MA 02115
Medical Research: What is the background for this study? What are the main findings?
Dr. Kang: Glaucoma is a leading cause of irreversible blindness worldwide, and primary open-angle glaucoma (POAG) is the most common form of the disease. Little is known on the causes of glaucoma but dysfunction in the regulation of blood flow to the optic nerve, which transmits visual information to the brain, may be involved. Nitric oxide is important for maintenance of blood flow and its signaling may be impaired in glaucoma. We were interested in whether dietary nitrates, an exogenous source of nitric oxide mostly found in green-leafy vegetables, may be related to lower risk of POAG.
Medical Research: What is the background for this study? What are the main findings?
Dr. Kang: We (Brigham and Women’s Hospital / Harvard Medical School and Massachusetts Eye and Ear researchers) used 25+ years of data from over 100,000 participants in the Nurses' Health Study (63,893 women) and the Health Professionals Follow-up Study (41,094 men). Participants were nurses or other health professionals and were aged 40 years or older and reported eye exams. We collected information on their diet and other health information every two years with questionnaires. During follow-up, 1,483 new cases of primary open-angle glaucoma with visual field loss were identified and confirmed with medical record review. Participants were divided into quintiles (one of five groups) of dietary nitrate intake (quintile 5, approximately 240 mg/day; quintile 1, approximately 80 mg/day) and of green leafy vegetables (quintile 5, approximately 1.5 servings/day; quintile 1, approximately one-third of a serving/day). We observed that greater intake of dietary nitrate and green leafy vegetables (e.g., romaine and iceberg lettuce and kale/chard/mustard greens) was associated with a 20 percent to 30 percent lower POAG risk; the association was particularly strong (40 percent-50 percent lower risk) for POAG with early paracentral visual field loss (a subtype of POAG most linked to dysfunction in blood flow autoregulation).
Dr. Woodward[/caption]
MedicalResearch.com Interview with:
Maria A. Woodward, MD
Department of Ophthalmology and Visual Sciences
University of Michigan
Ann Arbor, MI 48105
Medical Research: What is the background for this study? What are the main findings?
Dr. Woodward: The research was sparked by questions whether changes to the eye with keratoconus affect other parts of the body. There is conflicting information from past research about connections between systemic diseases and keratoconus. This creates confusion for patients and for doctors treating these patients.
Dr. Christina Weng[/caption]
MedicalResearch.com Interview with:
Christina Y. Weng, MD, MBA
Assistant Professor-Vitreoretinal Diseases & Surgery
Baylor College of Medicine-Cullen Eye Institute
Medical Research: What is the background for this study? What are the main findings?
Dr. Weng: Telemedicine has been around for a long time, but only recently have technological advances solidified its utility as a reliable, effective, and cost-efficient method of healthcare provision. The application of telemedicine in the field of ophthalmology has been propelled by the development of high-quality non-mydriatic cameras, HIPAA-compliant servers for the storage and transfer of patient data, and the growing demand for ophthalmological care despite the relatively stagnant supply of eye care specialists. The global epidemic of diabetes mellitus has contributed significantly to this growing demand, as the majority of patients with diabetes will develop diabetic retinopathy in their lifetime.
Today, there are over 29 million Americans with diabetes, and diabetic retinopathy is the leading cause of blindness in working age adults in the United States. The American Academy of Ophthalmology’s and American Diabetes Association’s formal screening guidelines recommend that all diabetic patients receive an annual dilated funduscopic examination. Unfortunately, the compliance rate with this recommendation is quite dismal at an estimated 50-65%. It is even lower amongst minority populations which comprise the demographic majority of those served by the Harris Health System in Harris County, Texas, the third most populous county in the United States.
In 2013, the Harris Health System initiated a teleretinal screening program housed by eight of the district’s primary care clinics. In this system, patients with diabetes are identified by their primary care provider (PCP) during their appointments, immediately directed to receive funduscopic photographs by trained on-site personnel operating non-mydriatic cameras, and provided a follow-up recommendation (e.g., referral for in-clinic examination versus repeat imaging in 1 year) depending on the interpretation of their images. The images included in our study were interpreted via two different ways—once by the IRISTM (Intelligent Retinal Imaging Systems) proprietary auto-reader and then again by a trained ophthalmic specialist from the IRISTM reading center. The primary aim of this study was to evaluate the utility of the auto-reader by comparing its results to those of the reading center.
Data for 15,015 screened diabetic patients (30,030 eyes) were included. The sensitivity of the auto-reader in detecting severe non-proliferative diabetic retinopathy or worse, deemed sight threatening diabetic eye disease (STDED), compared to the reading center interpretation of the same images was 66.4% (95% confidence interval [CI] 62.8% - 69.9%) with a false negative rate of 2%. In a population where 15.8% of diabetics have STDED, the negative predictive value of the auto-reader was 97.8% (CI 96.8% - 98.6%).
Dr. Thompson[/caption]
MedicalResearch.com Interview with:
Professor Benjamin Thompson PhD
School of Optometry and Vision Science
Faculty of Science, University of Waterloo
Waterloo, Ontario
Canada
Medical Research: What is the background for this study?
Dr. Thompson: Our investigation was part of the longitudinal Infant Development and Environment and Lifestyle (IDEAL) study that was designed to investigate the effect of prenatal methamphetamine exposure on neurodevelopment. Although the negative impact of prenatal drug exposure on a wide range of neurodevelopmental outcomes such cognitive and motor function is established, the effect on vision is not well understood. To address this issue, vision testing was conducted when children in the New Zealand arm of the IDEAL study turned four and half years of age.
Although the primary focus of the IDEAL study was the impact of methamphetamine on neurodevelopment, the majority of children enrolled in the study were exposed to a range of different drugs prenatally including marijuana, nicotine and alcohol. Many children were exposed to multiple drugs. This allowed us to investigate the impact of individual drugs and their combination on the children’s visual development.
Alongside standard clinical vision tests such as visual acuity (the ‘sharpness’ of vision) and stereopsis (3D vision), we also tested the children’s ability to process complex moving patterns. This test, known as global motion perception, targets a specific network of higher-level visual areas in the brain that are thought to be particularly vulnerable to neurodevelopmental risk factors.
Dr. Berg[/caption]
MedicalResearch.com Interview with:
Karina Birgitta Berg MD
Department of Ophthalmology
Oslo University Hospital
Oslo, Norway
Medical Research: What is the background for this study? What are the main findings?
Dr. Berg: Neovascular age-related macular degeneration (nAMD) has been the leading cause of vision loss in the elderly population of Western countries. Inhibition of vascular endothelial growth factor (VEGF) with medications such as bevacizumab and ranibizumab injected into the eye, has dramatically reduced the incidence of social blindness from this disease.
Dr. McKay[/caption]
MedicalResearch.com Interview with:
Brian S. McKay, Ph.D
Associate Professor
Department of Ophthalmology and Vision Science
University of Arizona
Medical Research Building, Room 212
Tucson, AZ 85724
Medical Research: What is the background for this study?
Dr. McKay: AMD (age-related macular degeneration) is a disease that is race-related. White people get the disease and lose vision to AMD at much higher rate than Blacks or Hispanics.
Thus, while race is complex, pigmentation may protect from the disease. With this starting point, my laboratory went after the pigmentation pathway to determine how pigment may affect photoreceptor (the retinal cells that actually catch the light) survival. The pigmented cells in the back of the eye are the retinal pigment epithelial cells (RPE), the rest of the retina does not pigment, it is clear not brown. We discovered that when the RPE make pigment they turn on molecular pathways to foster photoreceptor survival. Next we discovered the ligand for a receptor on the RPE that was tied to governing photoreceptor survival and pigmentation. That ligand was L-DOPA.
Knowing that L-DOPA is given to many aging individuals (those at risk of AMD), we developed a team to ask whether those taking L-DOPA for movement disorders are protected from AMD.














