Can a New Type of Blood Test Identify Macular Degeneration Much Earlier? New Research Says Yes

Cover of the journal Ophthalmology

New research led by the AMD Center of Excellence at Harvard Medical School, the University of Coimbra, Portugal, and Brigham and Women’s Hospital has used an emerging field of study, called “metabolomics” (explained below), to test patients’ blood and identify blood profiles that are associated with age-related macular degeneration (AMD).

According to study co-author Joan W. Miller, M.D., “With metabolomics, we can identify blood profiles associated with AMD and its severity through laboratory testing. Because the signs and symptoms of early-stage AMD are very subtle, with visual symptoms only becoming apparent at more advanced stages of the disease, identification of [indicators of AMD] in human blood plasma may allow us to better understand the early to intermediate stages of AMD so we may intervene sooner and ultimately provide better care.”

From the Journal Ophthalmology

This new macular degeneration blood testing research, titled Human Plasma Metabolomics Study Across All Stages of Age-Related Macular Degeneration Identifies Potential Lipid Biomarkers (explained below), has been published online ahead of print in the September 2017 edition of Ophthalmology, the official journal of the American Academy of Ophthalmology. Ophthalmology publishes original, peer-reviewed research in ophthalmology, including new diagnostic and surgical techniques, the latest drug findings, and results of clinical trials.

The authors are Inês Laíns, MD, MSc; Rachel S. Kelly, PhD; John B. Miller, MD; Rufino Silva, MD, PhD; Demetrios G. Vavvas, MD, PhD; Ivana K. Kim, MD; Joaquim N. Murta, MD, PhD; Jessica Lasky-Su, PhD; Joan W. Miller, MD; and Deeba Husain, MD, who represent the following institutions: Harvard Medical School, Boston, Massachusetts; the University of Coimbra, Portugal; the Association for Innovation and Biomedical Research on Light and Image, Coimbra, Portugal; and Brigham and Women’s Hospital, Boston, Massachusetts.

First, An Explanation of Terms Used in the Research

Here is a brief explanation of some key terms used in this macular degeneration research:

  • Biomarker: A substance in the body that can be measured and whose presence indicates disease, infection, or environmental exposure.
  • Lipid: A substance that is oily to the touch and does not dissolve in water. In the body, lipids store energy and are one of the components of the cells in our bodies.
  • Metabolomics: An emerging field of study that identifies “metabolites,” the unique chemical “fingerprints” that specific cell processes leave behind in our bodies.
  • Metabolites: Tiny particles in our bodies that reflect our specific genes and environment, produced during metabolism.
  • Metabolism: The chemical processes that occur within our bodies in order to maintain life.
  • Plasma: The liquid part of blood, which makes up about half the volume of blood. It holds the blood cells in suspension.

About the Macular Degeneration Blood Testing Research

Edited and excerpted from Researchers identify potential biomarkers of age-related macular degeneration, via Medical Xpress:

Patients with any stage of age-related macular degeneration (AMD) carry signs of the disease in their blood that may be found through special laboratory tests, according to a new study. The study describes a new technique known as “metabolomics,” which can identify blood profiles associated with AMD and its level of severity. These potential lipid biomarkers in human blood plasma may lead to earlier diagnosis, better [predicting] information, and more precise treatment of patients with AMD, as well as potential new targets for AMD treatment.

“With metabolomics, we can identify blood profiles associated with AMD and its severity through laboratory testing,” said co-author Joan W. Miller, M.D. “Because the signs and symptoms of early stage AMD are very subtle, with visual symptoms only becoming apparent at more advanced stages of the disease, identification of biomarkers in human blood plasma may allow us to better understand the early to intermediate stages of AMD so we may intervene sooner, and ultimately provide better care.”

“The study used a technique known as metabolomics, or the study of the tiny particles called metabolites, in our body that reflect our genes and environment,” explained co-author Ines Lains, M.D. “The metabolome—the set of metabolites present in an individual—is thought to closely represent the true functional state of complex diseases.”

“This is why we used it to test 90 blood samples obtained from study participants with all stages of AMD (30 with early-stage disease, 30 with intermediate-stage, and 30 with late-stage) and 30 samples from patients without AMD.”

Their [study] revealed 87 metabolites, or small molecules in the blood, that were significantly different between subjects with AMD and those without. Furthermore, the [research] team noted varying characteristics between the blood profiles of each stage of disease. This information has the potential to improve earlier diagnoses for AMD patients, and ultimately, may lead to more treatment options, as well as personalized treatment, for earlier stages of the disease.

More About Age-Related Macular Degeneration

NEI image of how someone with macular degeneration sees: overall blurriness with a blind spot in the center
Seeing the world with AMD

Age-related macular degeneration (AMD) is a gradual, progressive, painless deterioration of the macula, the small sensitive area in the center of the retina that provides clear central vision. Damage to the macula impairs the central (or “detail”) vision that helps with essential everyday activities, such as reading, preparing meals, watching television, playing card and board games, and sewing.

AMD is the leading cause of vision loss for people aged 60 and older in the United States. According to the American Academy of Ophthalmology, 10-15 million people have AMD and about 10% of people who are affected have the “wet” type of AMD.

Wet (Neovascular) Macular Degeneration

In wet, or exudative, macular degeneration (AMD), the choroid (a part of the eye containing blood vessels that nourish the retina) begins to sprout abnormal new blood vessels that develop into a cluster under the macula, called choroidal neovascularization (neo = new; vascular = blood vessels).

Because these new blood vessels are abnormal, they tend to break, bleed, and leak fluid under the macula, causing it to lift up and pull away from its base. This damages the fragile photoreceptor cells, which sense and receive light, resulting in a rapid and severe loss of central vision.

About Dry Macular Degeneration

The dry (also called atrophic) type of AMD affects approximately 80-90% of individuals with AMD. Its cause is unknown, it tends to progress more slowly than the wet type, and there is not – as of yet – an approved treatment or cure. “Atrophy” refers to the degeneration of cells in a portion of the body; in this case, the cell degeneration occurs in the retina.

In dry age-related macular degeneration, small white or yellowish deposits, called drusen, form on the retina, in the macula, causing it to deteriorate or degenerate over time.

Photograph of a retina with drusen

A retina with drusen

Drusen are the hallmark of dry AMD. These small yellow deposits beneath the retina are a buildup of waste materials, composed of cholesterol, protein, and fats. Typically, when drusen first form, they do not cause vision loss. However, they are a risk factor for progressing to vision loss.

Risk Factors for Macular Degeneration

The primary risk factors for AMD include the following:

  1. Smoking: Current smokers have a 2-3 times higher risk for developing AMD than do people who never smoked. It’s best to avoid second-hand smoke as well.
  2. Sunlight: Ultraviolet (UV) light is not visible to the human eye, but can damage the lens and retina. Blue light waves that make the sky, or any object, appear blue, are visible to the human eye and can also damage the lens and retina. Living Well with Low Vision reports on these lighting issues in Artificial Lighting and the Blue Light Hazard. Avoid UV light and blue/violet light as much as possible by wearing sunglasses with an amber, brown, or orange tint that blocks both blue and UV light.
  3. Uncontrolled hypertension: The National Eye Institute (NEI) reports that persons with hypertension were 1.5 times more likely to develop wet macular degeneration than persons without hypertension. It’s important to keep your blood pressure controlled within normal limits.
  4. A diet high in packaged, processed food and low in fresh vegetables: NEI suggests that eating antioxidant-rich foods, such as fresh fruits and dark green leafy vegetables (kale, collard greens, and spinach) may delay the onset or reduce the severity of AMD. Eating at least one serving of fatty fish (salmon, tuna, or trout) per week may also delay the onset or reduce the severity of AMD.
  5. Race: According to NEI, Whites/Caucasians are more likely to have AMD than people of African descent.
  6. Family history: NEI reports that individuals with a parent or sibling with AMD have a 3-4 times higher risk of developing AMD.

You can read more about the full range of AMD risk factors at Risk Factors for Age-Related Macular Degeneration on the VisionAware website.

More Advanced Information About the Study from Ophthalmology

Edited and excerpted from the study Abstract:

Purpose: To characterize the plasma metabolomics profile of patients with age-related macular degeneration (AMD) using mass spectrometry.

Participants: We prospectively recruited participants with a diagnosis of AMD and a control group (greater than 50 years old) without any [retinal] disease. [Editor’s note: A prospective study tests the subjects and then follows them into the future.]

Methods: All participants underwent color fundus photography, used for AMD diagnosis and staging, according to the Age-Related Eye Disease Study classification scheme. Fasting blood samples were collected and plasma was analyzed by Metabolon, Inc., using ultrahigh-performance liquid chromatography and high-resolution mass spectrometry. [The research assessed] differences in the metabolomic profiles of AMD patients versus controls, while controlling for potential confounders.

Results: We included 90 participants with AMD (30 with early AMD, 30 with intermediate AMD, and 30 with late AMD) and 30 controls. Using ultrahigh-performance liquid chromatography and mass spectrometry, 878 biochemicals were identified.

[The research analysis] identified 87 metabolites with levels that differed significantly between AMD patients and the controls. Most of these metabolites (82.8%), including the most significant metabolites, belonged to the lipid pathways. [Research analysis] revealed that of the 87 metabolites, 48 (55.2%) also were significantly different across the different stages of AMD.

Conclusions: Participants with AMD have altered plasma metabolomic profiles compared with controls…. These findings have the potential to improve our understanding of AMD pathogenesis, to support the development of plasma-based metabolomics biomarkers of AMD, and to identify novel targets for treatment of this blinding disease.

Additional Information About Macular Degeneration