Patients With Glaucoma Can Be Taught To Measure Their Own Intraocular Pressure

MedicalResearch.com Interview with:

Andrew Tatham Consultant Ophthalmologist Princess Alexandra Eye Pavilion and Department of Ophthalmology University of Edinburgh, Scotland

Dr. Tatham

Andrew Tatham, FRCOphth
Consultant Ophthalmologist
Princess Alexandra Eye Pavilion and Department of Ophthalmology
University of Edinburgh, Scotland 

MedicalResearch.com: What is the background for this study?

Response: Raised intraocular pressure (IOP) is the major risk factor for the development of glaucoma, the most common cause of irreversible blindness, with lowering IOP the only proven treatment.

Until recently the only way to measure IOP was for patients to visit their clinician  meaning it was only possible to obtain a limited number of measurements. This is problematic given that IOP fluctuates and that 75% of individuals have peak IOP outside office hours. If patients could measure their own IOP it would allow far more measurements to be obtained and result in better understanding of the variation and peaks in IOP. This could improve the detection of glaucoma and determine if patients are adequately controlled with medication.

Recently, a patient-operated, home IOP monitoring device (iCare HOME) has become available. The patient holds the device close to their eye and the device automatically determines if it is in the correct position to take a measurement. The tonometer then deploys a small probe which gently bounces off the surface of the eye to determine IOP. As the probe is only in contact with the surface of the eye for a few milliseconds no anesthetic is needed.

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Glaucoma Patients Might Want To Avoid Downward Dogs

More on Ophthalmology on MedicalResearch.com
MedicalResearch.com Interview with:
Robert Ritch, MD, FACS
Shelley and Steven Einhorn Distinguished Chair
Professor of Ophthalmology
Surgeon Director Emeritus and Chief, Glaucoma Services
Founder, Medical Director and Chairman, Scientific Advisory Board
The Glaucoma Foundation
Jessica V. Jasien MEn
Einhorn Clinical Research Center

The New York Eye and Ear Infirmary of Mount Sinai
New York, NY 10003

Medical Research: What is the background for this study? What are the main findings?

Response: Glaucoma is the leading cause of irreversible blindness in the United States and elevated intraocular pressure (IOP) is the most common known risk factor for glaucomatous damage. At the current time, IOP is the only modifiable risk factor for which treatment has a proven effect on preventing or slowing the progress of the disease.

The story behind this study goes back to 1980, when we saw a 45-year-old woman with severe damage from normal-tension glaucoma, which then was thought to be a disease of the elderly and also thought to be rare, which we now realize was erroneous. The causes of normal-tension glaucoma were also poorly understood. It turned out on questioning that this particular patient had been performing yoga and standing on her head for 20 minutes a day for 20 years. We measured her IOP in this position and it rose from 15 mmHg in the sitting position to 60 mmHg. When measured lying flat, it was 30 mmHg. We measured everyone working in the department standing on their heads and the IOP roughly doubled in each of them. This was our first inkling that marked changes in IOP could result from changes in body position.

The background for this study came from the lack of knowledge of IOP rises during yoga inversions, other than the headstand position. We looked at four common inverted yoga positions in glaucoma patients and healthy patients who were all experienced in practicing yoga. The four positions tested were downward facing dog, plow, legs up the wall, and forward bend. Each position showed a direct increase in IOP immediately assuming the yoga position, however the IOP dropped once assuming the seated position after two minutes in the yoga position. The most significant increase in IOP was seen during the downward facing dog position. IOP of each study participant was taken seated (baseline), immediately assuming the yoga position, which was held for two minutes, again at the two minutes of the yoga position, immediately in the seated position following the yoga position, and again after 10 minutes in the seated position. Each position was tested once in this order of IOP measurements.

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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).

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Glaucoma Linked To Overall Higher Health Care Costs

More on Health Care Costs on MedicalResearch.com

MedicalResearch.com Interview with:
Alisa Prager BS
Bernard and Shirlee Brown Glaucoma Research Laboratory
Department of Ophthalmology
Edward S. Harkness Eye Institute
Columbia University Medical Center, New York, New York

MedicalResearch: What is the background for this study? 

Response: The goal of this research was to better understand the impact of glaucoma on non-ophthalmic healthcare use and costs. While there have been other studies assessing costs associated with glaucoma, these studies were primarily derived from either claims data or chart review. Our study used the Medicare Current Beneficiary Survey, which is a dataset that links claims data with survey results. The advantage of this is that the survey data allowed us to assess patient reported outcomes that did not necessarily prompt an encounter with the health care system, such as recent falls or feelings of sadness. The MCBS also provides complete expenditure and source of payment data on health services, including those not covered by Medicare, which allowed us to look at a more full spectrum of both private and public healthcare use and costs among Medicare beneficiaries.

MedicalResearch: What are the main findings?

Response: We found that Medicare beneficiaries with glaucoma have 27% higher likelihood of inpatient hospitalizations and home health aide visits compared to those without glaucoma, even after adjusting for covariates and excluding individuals who were admitted to the hospital with a diagnosis of glaucoma. When we stratified glaucoma patients based on self-reported visual disability, we found that those with self-reported visual disability were more likely to complain of depression, falls and difficulty walking compared to those without.

We also found that glaucoma patients incurred a predicted $2,903 higher mean annual total healthcare costs from all sources compared to those without glaucoma after adjusting for socioeconomic factors and comorbidities. Costs were higher among those who reported visual disability, and remained higher after excluding outpatient payments.

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Newer Glaucoma Treatments May Be Best For Less Advanced Disease

MedicalResearch.com Interview with:
Pradeep Ramulu MD MHS PhD

Associate Professor of Ophthalmology
Wilmer Eye Institute
Johns Hopkins University

MedicalResearch: What is the background for this study? What are the main findings?

Dr. Ramulu: Looking at what procedures are used allows us to understand what doctors are doing, and how the landscape of our field is changing. We noted that overall numbers for glaucoma procedures were down – a surprise given that our population is aging, there are more Medicare beneficiaries, and there have not been recent advances in medical therapy for glaucoma.

MedicalResearch: What should clinicians and patients take away from your report?

Dr. Ramulu: There is a strong trend towards newer glaucoma procedures, particularly endocyclophotocoagulation, external mini-shunts, and canaloplasty. At the same time, traditional procedures such as trabeculectomy and tube shunts are still quite common, and the growth of these newer procedures should not imply that they treat glaucoma better than conventional therapies. It is also important for patients to realize that these newer therapies are often best suited as an initial therapy for less advanced disease.

MedicalResearch: What recommendations do you have for future research as a result of this study?

Dr. Ramulu: Our hope is that there is increasing research to help understand the efficacy of these newer treatments in the treatment of glaucoma, particularly in the form of head-to-head trials with more conventional therapy.

Citation:

Use of Various Glaucoma Surgeries and Procedures in Medicare Beneficiaries from 1994 to 2012

Arora, Karun S. et al.

Ophthalmology
DOI: http://dx.doi.org/10.1016/j.ophtha.2015.04.015

Pradeep Ramulu MD MHS PhD, Associate Professor of Ophthalmology, Wilmer Eye Institute, & Johns Hopkins University (2015). Newer Glaucoma Treatments May Be Best For Less Advanced Disease 

Metformin Linked To Reduced Risk of Glaucoma

Julia E. Richards, Ph.D. Harold F. Falls Professor of Ophthalmology and Visual Sciences Professor of Epidemiology Director, Glaucoma Research Center The University of MichiganMedicalResearch.com Interview with:
Julia E. Richards, Ph.D.

Harold F. Falls Professor of Ophthalmology and Visual Sciences
Professor of Epidemiology
Director, Glaucoma Research Center
The University of Michigan

Medical Research: What is the background for this study?

Response: We have a special interest in how the developmental processes of aging increase the risk of late onset diseases. We wondered whether drugs that target known aging pathways might be able to reduce risk of late onset disease. In the aging field, an emerging area of interest has been the category of drugs called caloric restriction mimetic (CRM) drugs, which have been found to extend life span and to reduce risk or delay onset of some late-onset diseases. These caloric restriction mimetic drugs target a set of pathways that have come to be seen as playing roles in longevity. One of these caloric restriction mimetic drugs, metformin, happens to also be one of the most common drugs used in the treatment of type 2 diabetes.

Glaucoma is a leading cause of blindness worldwide and classical open-angle glaucoma shows onset in late middle age or late age, so we hypothesized that a caloric restriction mimetic drug might be able to reduce the risk of open-angle glaucoma. We used data from a large health services database to compare the rate at which open-angle glaucoma developed in individuals with diabetes mellitus who used metformin versus those who did not use metformin. We predicted that metformin would be associated with reduced risk of open-angle glaucoma.

Medical Research: What are the main findings?

Response: We found that use of metformin was associated with reduced risk of open-angle glaucoma. A 2 gram per day dose of the CRM drug metformin for two years was associated with a 20.8% reduction in risk of developing open-angle glaucoma. When we looked at the highest quartile of drug prescribed (>1,100 grams over a two year period) we found a 25% reduction in risk relative to those taking no metformin. This risk reduction is seen even when we account for glycemic control in the form of glycated hemoglobin, and use of other diabetes drugs was not associated with reduced risk of open-angle glaucoma. A possible explanation for our findings might be that the mechanism of risk reduction is taking place by CRM drug mechanisms that target aging pathways rather than through glycemic control of diabetes.

In the long run, the approaches to late onset diseases in general will become much more powerful if we can use parallel approaches that simultaneously target both the aging processes going on and the disease-specific pathways going on. In the literature we see caloric restriction mimetic drugs metformin, rapamycin and resveratrol all being explored for their ability to target points in aging pathways in ways that can impact the risk of a variety of late-onset diseases, so it will be important for those interested in the risk factors affecting late onset diseases to pay attention to how caloric restriction mimetic drugs might be altering risk for those late onset diseases. Continue reading

Decreased Medicare Payment Did Not Mean Increased Volume For Most Glaucoma Procedures

MedicalResearch.com Interview with: Dan Gong BA Yale University School of MedicineMedicalResearch.com Interview with:
Dan Gong BA
Yale University School of Medicine
————

James C. Tsai, M.D., M.B.A.
President – New York Eye and Ear Infirmary of Mount Sinai
Delafield-Rodgers Professor and Chair Department of Ophthalmology Icahn School of Medicine at Mount Sinai

Medical Research: What is the background for this study? What are the main findings?

  • Congress first introduced the Medicare Physician Fee Schedule built on the resource-based relative value scale (RBRVS) in the Omnibus Budget Reconciliation Act of 1989. Until recently, Medicare payments to physicians were adjusted annually based on the sustainable growth rate (SGR) formula.
  • When adjusting physician payments, one controversial belief by policymakers was the assumption that in response to fee reductions, physicians would recuperate one-half of lost revenue by increasing the volume and complexity of services.
  • This study questioned this assumption that this inverse relationship between Medicare payment and procedural volume is uniform across all procedures. In particular, glaucoma procedures have not been studied in the past.
  • Using a fixed effects regression model, we found that for six commonly performed glaucoma procedures, four did not have any significant Medicare payment and procedural volume relationship (laser trabeculoplasty, trabeculectomy with and without previous surgery, aqueous shunt to reservoir). Two procedures, laser iridotomy and scleral reinforcement with graft, did have significant and inverse associations between Medicare payment and procedural volume. Continue reading

Sleep Disturbance in Glaucoma Patients Due To Retinal Ganglion Cell Death

MedicalResearch.com Interview with: Carolina P B Gracitelli, M.D. Ophthalmology - PhD Candidate/ Research Fellow University of California San Diego - Hamilton Glaucoma Center  Medical Research: What is the background for this study? What are the main findings?  Dr. Gracitelli:  Of all the diseases that can lead to blindness, glaucoma is one of the most important diseases; it affects more than 70 million people worldwide, of whom approximately 10 % are bilaterally blind. Different studies have reported that the damage caused by glaucomatous disease lead to retinal ganglion cell (RGC) loss and consequently loss of intrinsically photosensitive retinal ganglion cells (ipRGCs), which is a subtype of RGC. This subpopulation of RGC is clearly related with non-image-forming visual function such as photic synchronization of circadian rhythms  and the pupillary light reflex. However, the true impact of glaucoma on sleep quality, sleep disturbance or circadian rhythm was until nowadays controversial. The main clinical finding of our study was that glaucoma leads to RGC death, including ipRGC death. These cells are connected to several non-image-forming functions, including circadian photoentrainment and pupillary reflexes. Therefore, the image-forming and non-image-forming visual systems are associated with glaucoma. Circadian function has not been well investigated in clinical daily practice, but it can interfere with the quality of life of these patients. Concerns about sleep disturbances in glaucoma patients should be incorporated into clinical evaluations.   Medical Research: What should clinicians and patients take away from your report? Dr. Gracitelli:  Our data support the concept that glaucoma is associated with a loss of ipRGCs that mediate the pupillary light response, particularly to the sustained component of the blue flash with a luminance of 250 cd/m2. Additionally, glaucoma patients had significant sleep disturbances that were inversely correlated with a measure of ipRGC function, the pupillary light reflex. These results suggest that the loss of ipRGCs in glaucoma may also lead to sleep disturbances. Both non-visual functions of ipRGCs are correlated, indicating that attention should be paid to the non-image forming visual functions in glaucoma patients.   Medical Research: What recommendations do you have for future research as a result of this study?  Dr. Gracitelli:  Sleep disorders is a complex system, therefore, some conclusions in this study should be carefully evaluated. Further studies with larger cohorts could also help to elucidate the association between the pupillary reflex and the polysomnography parameters. And longitudinal studies can better explain the associations between sleep disorders and glaucoma progression.  In addition, we know that there are several types of ipRGCs and they have specific functions (pupillary reflex or circadian rhythms), therefore, evaluations would also need to include a more thorough assessment to understand better the specific role of ipRGCs in sleep disturbances. However, it is true that these ipRGCs functions are impaired in glaucoma, affecting the quality of life of these patients.   Citation:   Intrinsically Photosensitive Retinal Ganglion Cell Activity Is Associated with Decreased Sleep Quality in Patients with Glaucoma  Gracitelli, Carolina P.B. et al. Ophthalmology Published Online: April 06, 2015 DOI: http://dx.doi.org/10.1016/j.ophtha.2015.02.030MedicalResearch.com Interview with:
Carolina P B Gracitelli, M.D.
Ophthalmology – PhD Candidate/ Research Fellow
University of California San Diego – Hamilton Glaucoma Center

Medical Research: What is the background for this study? What are the main findings?

Dr. Gracitelli: Of all the diseases that can lead to blindness, glaucoma is one of the most important diseases; it affects more than 70 million people worldwide, of whom approximately 10 % are bilaterally blind. Different studies have reported that the damage caused by glaucomatous disease lead to retinal ganglion cell (RGC) loss and consequently loss of intrinsically photosensitive retinal ganglion cells (ipRGCs), which is a subtype of retinal ganglion cell. This subpopulation of RGC is clearly related with non-image-forming visual function such as photic synchronization of circadian rhythms and the pupillary light reflex. However, the true impact of glaucoma on sleep quality, sleep disturbance or circadian rhythm was until nowadays controversial.

The main clinical finding of our study was that glaucoma leads to retinal ganglion cell death, including ipRGC death. These cells are connected to several non-image-forming functions, including circadian photoentrainment and pupillary reflexes. Therefore, the image-forming and non-image-forming visual systems are associated with glaucoma. Circadian function has not been well investigated in clinical daily practice, but it can interfere with the quality of life of these patients. Concerns about sleep disturbances in glaucoma patients should be incorporated into clinical evaluations.

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High Blood Pressure Must Be Carefully Managed In Glaucoma Patients

MedicalResearch.com Interview with:
Zheng He and Bang V. Bui

Department of Optometry & Vision Sciences
University of Melbourne, Parkville, Australia

Medical Research: What is the background for this study? What are the main findings?

Response: Glaucoma, the second leading cause of blindness in the world, is a condition that occurs when too much pressure builds up inside the eye. This excess pressure injures the optic nerve (the wire that transmits visual information to the brain) resulting in vision loss. Many risk factors for glaucoma are not well understood.

High blood pressure (> 140/90 mmHg) is probably the most common comorbidity in patients presenting to optometry clinics. The overall prevalence of hypertension worldwide is over 26%, and increases dramatically with advancing age. Long-term hypertension leads to remodeling of the heart and blood vessels, promoting the risk of multiple end organ damage.

Whilst chronic hypertension is a well-documented risk factor for stroke, the link between hypertension and glaucoma remains unclear. Previously, it was thought that high blood pressure could counteract high intraocular pressure, which is a clear risk factor for glaucoma. However, this issue may be more complicated than first thought.

The Baltimore Eye Survey compared the prevalence of glaucoma in young and older patients with hypertension. They found that young patients with high blood pressure were at lower risk of glaucoma compared to the entire cohort. This outcome is consistent with the idea that higher blood pressure provides better perfusion pressure to the eye. Paradoxically systemic hypertension in older subjects actually increased the risk of glaucoma. Its seems that longer durations of systemic hypertension impact glaucoma risk negatively. One explanation for this is that any benefit from high blood pressure counteracting high eye pressure is lost as damage to blood vessels — a consequence of hypertension — becomes more dominant.

This hypothesis was tested by comparing the effect of acute (one hour) and chronic (four weeks) hypertension in lab rats with elevated eye pressure. When blood pressure was raised for four weeks, there was less functional protection against eye pressure elevation compared with the one-hour case. This shows that having high blood pressure for a longer time compromises the eye’s capacity to cope with high eye pressure. This impairment was associated with thicker and narrower blood vessels and a reduced capacity for the eye to maintain blood flow at normal levels in response to eye pressure elevation (this process is known as autoregulation). Thus in chronic hypertension, smaller reduction in ocular perfusion pressure can result in blood flow deficiency.

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Detecting glaucoma before it blinds

Early detection and diagnosis of open angle glaucoma important so that treatment can be used in the early stages of the disease developing to prevent or avoid further vision loss. Writing in a forthcoming issue of the International Journal of Medical Engineering and Informatics, researchers in the US have analyzed and ranked the various risk factors for open angle glaucoma so that patients can be screened at an earlier stage if they are more likely to develop the condition.

Glaucoma is one of the main leading causes of blindness; it is a progressive and irreversible disease. Of the various forms of glaucoma, open angle glaucoma (OAG) is the most common and can cause the most damage. Unfortunately, unless a patient is undergoing regular screening from about the age of 40 years because of a family history, it is otherwise difficult to detect until substantial and irreversible vision loss has occurred. Glaucoma is the third leading cause of blindness worldwide and the second leading cause of blindness in the USA.

Now, Duo Zhou and colleagues at the University of Medicine and Dentistry of New Jersey, Newark, have used statistical collinearity analysis to evaluate risk factors for OAG, and logistic regression models to identify a minimum set of such risk factors for prognosis and diagnosis of the disease. Their study was based on more than 400 patients with subtle or severe vision problems who attended hospital. It reveals the relative risk of being a smoker, age, visual “field test” results, presence of a localized notch or thinning of the neuroretinal rim identified during standard eye examination, cup to disk ratio (a measure of restriction of the optic nerve at the back of the eye) and other factors.

The data are complex and separating out predictors from diagnostic factors was difficult, the team admits. However, they suggest that family history, medical history, current medications, geographic location, visual field test and ocular examination must all be considered in diagnosis and prognosis for OAG. They have excluded certain factors from the OAG prognosis: gender, race, family history of glaucoma, diabetes mellitus, hypercholesterolemia, thyroid disease, migraine, Reynaud’s disease and myopia as these have no direct effect on OAG development.

As revealed in the analyses, the odds of developing OAG will be increased by 91% with an increase in the Cup-to-Disc ratio of 0.1. Risk increases by 3% annually by age but decreases by 31% for every dB increase of mean deviation of Humphrey visual field. The odds of developing OAG will be 4.36 higher for patients with abnormal Humphrey visual filed overall test, 7.19 higher in patients with localized notch or thinning of the neuroretinal rim. Interestingly, patients with a smoking history seem to be less likely to develop OAG as compared to those with smoking history; although there are many smokers with OAG. Oddly, because of the location of the study, the team can also say that patients living in Atlantic/Quebec will be 73% less likely to develop OAG compared to their fellow Canadians in Ontario.

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Risk factors for open angle glaucoma – analyses using logistic regression” in Int. J. Medical Engineering and Informatics, 2011, 3, 203-222

Contact: Duo Zhou
duo.zhou@gmail.com
Inderscience Publishers