In December 2019, China reported an outbreak of the previously unknown COVID-19 to the World Health Organisation. By March 11, 2020, more than 100,000 people across the world had been infected and the WHO declared COVID-19 as a pandemic.
As of 10th November 2020, COVID-19 has infected more than 51 million people and killed over 1.2 million people in 216 countries and territories worldwide.
With no cure or vaccine for the disease yet, the world has had to adopt the age-old strategies for controlling contagious diseases i.e. quarantine and physical (or social) distancing. Countries have implemented lockdown measures to ensure that people stay home and do not move about unnecessarily.
Although all these measures are intended to curb the spread of the COVID-19 disease, they have taken a toll on the economy of the country and the health of the people. The economic ramifications of the pandemic are plain to see and will be the subject of the economists and financial experts for many years to come. In addition, the escalating numbers of those who have tested positive for or died from the disease are the headlines of current news. This article, on the other hand, will focus on the less obvious potential negative impact of these lockdown measures on the health of the eye.
The eyes are the organs of sight and 70 – 90% of all that we learn in life comes through these two 2.5 cm orbs. 4 In spite of the important role and sensitive nature of the eyes, most people often take the eyes for granted until something goes very wrong. In the face of such a global pandemic like the COVID-19, the eyes are even more likely to be ignored now.
The most obvious effects of the nationwide lockdown were the restriction on human movement and the reduction in physical activities which together with increased stress and boredom (another form of stress) for many people, if not everybody. Consequently, people developed various coping strategies, healthy and unhealthy ones, to adapt to the situation. It is these coping strategies which directly or indirectly affect the health of the eye.
Stress hormones and Vision loss
Stress often activates your sympathetic nervous system and leads to a cascade of physiological reactions known as a stress response (fight-or-flight response). This response, primarily controlled by a group of three glands i.e. hypothalamus, pituitary gland and adrenal gland, interferes with the normal levels of circulating hormones, including cortisol. 5
Cortisol is the main stress hormone of the body and is best known for fuelling your body’s “fight-or-flight” response in a crisis. However, it also controls your sleep/wake cycle, keeps inflammation down, regulates your blood pressure, increases blood sugar (glucose) and manages how your body uses carbohydrates, fats and proteins. 7 Cortisol is produced by the two adrenal glands located on top of each kidney and when the body is under stress, the glands release high amounts of the hormone into the blood.6, 7This narrows the arteries and increases heart rate, both of which cause the heart to pump blood harder and faster. Cortisol makes energy available to the large muscles by increasing blood glucose levels. Normally, after a stressful situation has passed, your cortisol levels should come down, and the body should return to a restful state. However, when there is constant stress, for example, as brought on by the COVID-19 pandemic, the body pumps out cortisol continuously and this causes problems for your general health as well as your eyes.
The constantly high blood pressure can cause leakages and inflammation of blood vessels which disrupt blood circulation to the retina and optic nerve. People who have conditions such as glaucoma, age-related macular degeneration and central serous chorioretinopathy may experience worsening symptoms.13 Stress has also been shown in some studies to increase the intraocular pressure (IOP) of the eye leading to a condition called ocular hypertension.
Studies have also shown the effect of cortisol on appetite and food cravings particularly for high calories food.9. It does this by either binding directly to the hypothalamus receptors in the brain or indirectly modulating other hormone and stress response factors. Food craving is an intense desire for a specific food which can seem uncontrollable and/or unbearable until that food is consumed, often in excess. Typically, the craved foods are high in carbohydrates, fats, or proteins (e.g. biscuits, chocolate, fizzy drinks, fried foods, meats, etc.). Whereas in other cases, the “food” has no nutritional value at all (e.g. saltpetre, chalk, “kanzo” (burnt food))
The excess intake of carbohydrates, fats or proteins negatively influences the production of serotonin, a neurotransmitter found in both the brain and the stomach which plays a key role in the control of mood, blood pressure, sleep, pain and pleasure. Therefore the combined effect of the psychological stress, lack of physical exercise and poor eating behaviour (food craving) increase the risk of developing vascular diseases, cardiovascular diseases, obesity, diminished immune system, depression, anxiety, and sleep disorders which in the long run affect the eyes.
Vascular conditions of the eyes such as aneurysms, occlusions and ischemia restrict blood flow to the eye particularly to the retina and can lead to blindness. Obesity is associated with the development of cataracts, diabetic retinopathy, macular degeneration, increased intraocular pressure (which can lead to glaucoma), retinal vein occlusion and stroke, all of which can cause blindness. People with pre-existing diabetes or hypertension have a higher risk and faster progression towards blindness.
A diminished immune system can result in the re-activation of a varicella-zoster virus resulting in herpes zoster ophthalmic and other infections that commonly affect the eyelids (styes), the cornea (keratitis) and the uvea (uveitis). Depression, anxiety and sleep disorders often result in complaints of tired, sore and baggy eyes, blurred vision, sensitivity to light, itching and redness16, 17and may lead to chronic eye conditions like dry eye syndrome.
Visual displays and Visual discomfort
Another phenomenon that has seen a rise in this period is the amount of time spent viewing electronic screens (phones, laptops, tablets, television). With physical distancing rules in place, more people now work remotely from home and rely more on their computers. Social media and video calls have become the new normal for keeping in touch with friend and family, while the television and the internet have become the means of relieving boredom. These activities are intermediate to near visual tasks that place a huge demand on the visual and result in a condition known as computer vision syndrome (CVS).
CVS refers to a group of eye and vision problems related to near work experienced after prolonged use of computers (or other personal digital display units). Symptoms include headaches, blurred vision, eye strain, neck and shoulder pains, among others
Currently, most digital display screens are liquid crystals displays (LCD). These types of screens emit more blue light compared to the cathode ray tube (CRT) displays used in the past. Excess blue light can damage retinal cells, leading to age-related macular degeneration.
Again, blue light disrupts sleep patterns through its suppressive effect on the hormone melatonin, which regulates sleep. Lack of sleep or disturbed sleep negatively affects alertness, eating patterns and moods.
Reducing your risk for vision loss in this pandemic
During these abnormal times where lockdown and quarantine are the order of the day, everyone needs to observe a healthy and balanced nutritional pattern where food containing a higher amount of minerals, antioxidants, vitamins are recommended. Fruits and vegetables have a rich supply of micronutrients to the body and will help boost the immune system. This will prevent the development and exacerbation of chronic conditions like diabetes, hypertension, and their collateral effects on the eye.
Again, a healthy amount of physical activities and regular exercise will help improve physiological functions of organ systems like nervous, musculoskeletal, immune, endocrine, digestive, circulatory, and even the visual system. People should get into some of the physical activities and exercises that can be done at home to stay healthy.
Those who are constantly under stress or anxiety should find ways to minimise stress and find a better work-life balance. One practice is to dedicate more time to things that one enjoys doing e.g. reading, cooking, sports, outdoor activities, etc.
Finally, as computers and televisions increasingly become an integral part of our lifestyle during this lockdown and quarantine, it is advisable to limit the time continuously spent on using computers, television. A five to ten-minute break for every hour behind the screen will provide relief to the eyes and help people avoid CVS in this time of COVID-19.
This article was written by Dr Jacob Mesuh (Optometrist, Foresight Medical Centre) [email protected] and Dr Enyam Morny (Lecturer and optometrist, Department of Optometry and Vision Science, University of Cape Coast) [email protected]
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