Oxidative Stress: How It Affects Your Eye

We have come to the end of the first month of the new year 2020. Many of us have started some new goals, and as life gets in the way, placed others on hold. My goal for this year is to be healthy in every area of my life. Putting my eyes as a priority was not a part of these health goals until I had a frightening pain in one of them. Like most people my age, I do the annual eye exam and have my prescription reviewed. Outside of that, I never really gave my eyes any thought except when I’m putting on my makeup. Like most people living in this period, we spend countless hours on the cellphone or glued to other electronic devices. Our eyes allow us to see and interact in this fast-paced electronic world, so why aren’t we paying more attention to them?

Having good vision is excellent, but we don’t realize how useful it is until we experience poor eyesight. Poor eyesight makes it challenging to read a road sign or a book, drive, garden, and take in the visual world. One of the factors that can indirectly contribute to poor eyesight is stress.

Impact of Stress
Chronic stress (bad stress) left unchecked can give rise to many health problems such as high blood pressure, heart disease, obesity, diabetes, and diabetic eye diseases. A growing body of research has indicated that regardless of gender, race, and age, chronic stress can change our DNA for the worse. Other studies have shown that oxidative stress is present before diabetic complications become clinically evident. There is also ongoing research to assess the relationship between oxidative stress and insulin sensitivity in non-diabetic individuals. But what we don’t hear a lot about is how oxidative stress affects the eyes.

Oxidative Stress
Oxidative stress in the eye, especially photo-oxidation, has played a significant role in ocular diseases. Ocular diseases are diseases that affect eye health and vision in people of all ages. Photo-oxidation is the exposure of tissues to ultraviolet radiation. This exposure affects the conjunctiva, cornea and plays a role in cataract formation in the lens, retinal and corneal degeneration, optic nerve pathologic conditions, inflammation in optic neuritis, and is degenerative in glaucoma. The blue light that is absorbed by the eye results in the formation of free radicals that contribute to oxidative stress in the retina. Research has shown that oxidative stress is a likely cause of age-related macular degeneration and cataract formation.

According to the American Optometric Association, “more than 99% of UV radiation is absorbed by the anterior structures of the eye, although some of it does reach the light-sensitive retina. The UV radiation present in sunlight is not useful for vision. There are good scientific reasons to be concerned that UV absorption by the eye may contribute to age-related changes in the eye and several serious eye diseases.”

Environmental Irritants

High levels of oxidants and low levels of antioxidants are also involved in the ocular aging process. Exposure to air pollution, radiation, cigarette smoke, vapors, or gases from household cleaning products directly affects the cornea and the anterior eye segment. Oxidative stress may trigger or develop ocular injury resulting in decreased visual acuity or even vision loss. These, however, are not the only risk factors that result in oxidative stress in the eyes.

Risk Factors

In 2011, doctors at the Washington University School of Medicine in St. Louis discovered when measuring oxygen during eye surgery, that African-Americans had higher levels of oxygen, which could explain this group’s higher risk of glaucoma than Caucasians. These doctors suspected that higher levels of oxygen might damage the drainage system in the eye, resulting in elevated pressure. Higher pressure can damage the optic nerve causing blindness. This study provided the first physiologic clue about the link between race and risk for glaucoma. It is important to note that glaucoma is the leading cause of blindness among African-Americans and Hispanics. Compared to Caucasians, glaucoma is about six times more common in African-Americans, and blindness caused by glaucoma is roughly 16 times more likely in African-Americans.

At-Risk Groups

In 2017, another study was conducted, which highlighted the racial differences in oxygen levels in the human eye and the impact of oxidative stress on the cornea and lens. Increased oxygen or oxygen metabolites may increase oxidative stress, cell damage, intraocular pressure, and the risk of developing glaucoma. An expanded study of territories outside of the US found similar results. The Barbados Eye Study showed that open-angle glaucoma was prevalent in 1 in 11 Afro-Caribbeans older than 50 years, and 1 in 6 older than 70 years old. On the island of St Lucia, the homogeneous Afro-Caribbean population has a prevalence of glaucoma significantly higher than that of the Caucasian populations in other studies.

The US National Library of Medicine/National Institutes of Health reported that African Americans and Hispanics have higher levels of oxidative stress than Caucasians, even after adjustment for differences in cardiovascular disease risk factors and inflammation. Studies have also shown that African-Americans and Hispanics are at a disproportionately higher risk for developing many of these o A growing body of research has indicated that regardless of gender, race, and age, chronic stress can change our DNA for the worse. Other studies have shown that oxidative stress is present before diabetic complications become clinically evident. Here are some simple steps that we can use to manage oxidation stress on the eyes.

Take Action

• Check your eyes regularly. You should have a dilated eye exam frequently to check for common eye problems. If you haven’t had an exam for some time, schedule one this month.
• Visit an eye care professional if you have any of the followings:
  • decreased vision
  • eye pain
  • drainage or redness of the eye
  • double vision; or diabetes
  • if you see flashes of light, floaters (specks that appear to float before your eyes),
  • circles (halos) around light sources.
• Follow your doctor’s and eye specialist’s instructions. Fill any prescription you are given, and take them as directed. Schedule a follow-up visit if you need one.
• Know your family’s eye health history. Genetics plays a role in many eye conditions, from common vision problems to more severe diseases that can cause blindness. Let your doctor or eye specialist know if eye diseases run in your family as you may be at a higher risk of developing the disease.
• Eat right to protect your sight—in particular, eat plenty of dark leafy greens such as spinach, kale, or collard greens, and fish that is high in omega-3 fatty acids and limit your intake of processed foods, particularly those high in sugars and fats.
• Maintain a healthy weight with diet and exercise.
• Wear protective eyewear when playing sports or doing activities around the home.
• Quit smoking.
• Wear sunglasses that block 99 percent of UVA and UVB radiation. Ultraviolet radiation reaches the eye not only from the sky above but also by reflection from the ground, especially water, snow, sand, and other bright surfaces. You can protect your eyes from sunlight by using both a brimmed hat or cap and UV absorbing eyewear. A wide-brimmed hat or cap will block roughly 50% of the UV radiation and reduces UV radiation that may enter above or around glasses. Additional protection for the retina can be provided by lenses that reduce the transmission of violet/blue light. Such lenses should not be so colored as to affect recognition of traffic signals.
• Clean your hands and your contact lenses properly to avoid the risk of infection.
• Practice workplace eye safety

Taking care of your eyes benefits your overall health. People with vision problems are more likely than those with good vision to have diabetes, poor hearing, heart problems, high blood pressure, lower back pain, stroke, as well as have increased risk for falls, injury, and depression.

Let 2020 be the year of healthy vision as we bless our eyes so that we may see.

Photo Credit: Photo by Roberto Cervantes from Pexels

SOURCES: Healthy Vision: Take care of your eyes! :https://www.cdc.gov/media/matte/2012/08-healthy-vision.pdf?cid=2012_08_healthy_vision

Ocular Ultraviolet Radiation Hazards In Sunlight A Cooperative Initiative of the National Society to Prevent Blindness; The American Optometric Association; The American Academy of Ophthalmology https://www.aoa.org/Documents/optometrists/ocular-ultraviolet.pdf

Race Differences in the Association of Oxidative Stress With Insulin Sensitivity in African‐ and European‐American Women: More oxygen in eyes of African-Americans may help explain glaucoma risk https://source.wustl.edu/2011/07/more-oxygen-in-eyes-of-africanamericans-may-help-explain-glaucoma-risk/

Racial Differences in Ocular Oxidative Metabolism. Implications for Ocular Disease https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5562541/

Effect of oxidative stress on racial differences in vascular function at rest and during handgrip exercise. https://www.ncbi.nlm.nih.gov/pubmed/28594709