‘Disease’ (dis-ease) is simply a condition of unstable health. Diseases occur when there is a shift from normal body structure and function.

Diseases that interfere with overall health by affecting body systems are called systemic diseases; while those which bring about abnormal changes in eye health are termed ‘ocular diseases’. These ocular diseases either result from direct insults to the eye or they can be linked to systemic diseases. When eye diseases are attributed to underlying health problems, they are referred to as ‘ocular complications’  of systemic disease.

This realization should not be over-surprising to say the least, considering that the human eye is part and parcel of the body; and not an organ in isolation from the rest of it.

Hence, here are ten systemic diseases which affect eye health:

HYPERTENSION: Hypertension is a disease that arises when blood pressure (B.P) is persistently increased above the normal. ‘B.P’ is the force which blood exerts on the vessels (veins & arteries) as it flows through them to reach the brain and everywhere else. Normal blood flow basically helps to move nutrients and oxygen to various parts of the body.

In chronic hypertension, the blood vessels are narrowed by fats (lipids) and cholesterols deposited within their walls. Hence, blood flows through these tight vessels with more force; causing increased pressure.

The eye is not isolated from this problem as well; normal blood circulation to the back of the eye known as the retina (which contains the major nerve for sight) also gets disrupted. In the long run, persistently elevated blood pressure stretches and thins out blood vessels of the retina. When blood pressure remains uncontrolled, these vessels are eventually overstretched; causing them to leak out blood and other fluid contents onto the back of the eye. These changes are known as hypertensive retinopathy  and can cause visual impairment, depending on the level of bleeding on the retina. So, individuals with hypertension should have their eyes checked regularly.

DIABETES (DM): Diabetes mellitus is a disease of abnormally high blood glucose (sugar) levels. It occurs due to failure of the body’s function of supplying much-needed glucose to the brain, retina and other parts of the body.

With regards to its effects on the eyes, uncontrolled diabetes causes occasional blurry vision by altering the shape of the eye’s lens. Long-term diabetes, particularly when poorly controlled, also changes the nature of the lens in the eye; leading to the formation of a cataract in the lens. Chronic diabetes also causes abnormal changes at the back of the eye, these changes are collectively termed diabetic retinopathy. In this condition, deeper blood vessels at the back of the eye are damaged. This causes blood and fluid to sip from damaged vessels onto the retina, thus causing reduced vision. If treatment for diabetic retinopathy is not sought early while the diabetes also remains uncontrolled, more severe complications are likely to occur.

SICKLE CELL (SS) TRAIT: Sickle cell anaemia is an inherited condition that affects individuals having the SS genotype. Blood is made up of ‘red’ blood cells which serve to circulate nutrients which are normally roundish in form, however, in this condition, these vital cells are abnormally sickle-shaped. This affects the body’s ability to circulate nutrients, oxygen and other substances needed to defend against disease. This also affects the flow of blood to the back of the eye, occasionally giving rise to a complication termed sickle cell retinopathy. This often involves bleeding at the back of the eye and can cause varying amounts of damage to vision.

Therefore, vision problems experienced by an ‘SS’ individual should be timely reported to the hospital so that possible ocular complications can be rule out or managed. 

MALARIA: Almost everyone knows that malaria is spread through mosquito bites; and that it usually begins with individuals showing signs of fever and weakness. However, many would be surprised to learn that this “everyday malaria” can also cause serious problems with vision. Now how does this happen?…

The common symptoms of malaria usually arise when malarial parasites (plasmodium spp.) repeatedly destroy blood cells in order to multiply within the body. Occasionally, these parasites may invade blood vessels around the brain in an attempt to destroy them. This then sets off adverse reactions within the brain, leading to a complicated form of malaria known as Cerebral malaria. This condition is potentially life-threatening, particularly in vulnerable individuals (e.g. children); often resulting in seizures, coma, mental imbalance and of course, visual problems. These visual complications are potentially blinding if not adequately handled and can only be recognized by your eye doctor. Therefore, avoid self-medication and seek expert opinion promptly.

ARTHRITIS: Arthritis is a condition which causes chronic pain and discomfort around the joints. ‘Rheumatoid’ arthritis is a form of arthritis which causes damage to a substance known as collagen. Collagen not only surrounds the ends of joints, but also makes up certain structures in the eye. Thus, for any damage sustained by the joints; some parts of the eyes also get affected. This tends to occasionally bring about sudden eye pain, redness and sensitivity to light. In order to protect the eyes from incurring avoidable damage, such complications must be properly managed. For people living with arthritis, a routine visit to your eye doctor; particularly following sudden eye pain, can make a great deal of difference.

TUBERCULOSIS: Tuberculosis (TB) is a disease which is primarily known for attacking the lungs. The common known signs of TB include coughing up blood, an ashen skin appearance and severe weight loss. Interestingly, a majority of individuals infected with TB do not show up these signs; however, they are predisposed to ocular complications due to tuberculosis as much as individuals who show up the expected signs of disease. When this happens, the middle layer of the eye (assuming the eye as a three-layered onion) may get inflamed; this causes pain, discomfort and reduced vision. Hence, your eye care practitioner can make a diagnosis of TB with the aid of lab tests if your eyes are suspected to show the necessary signs. Fascinating, isn’t it?

HIV/AIDS: HIV/AIDS is a disease condition in which the human immune system is suppressed by the HIV virus, reducing the body’s ability to defend itself against other infections. This includes diseases which affect the eyes when the body’s defenses are down.

Immunocompromised patients, such as those living with HIV/AIDS who fail to follow their antiretroviral treatment to the letter often develop ocular complications (like severe infections and cancers in and around their eyes).

STROKE: A stroke occurs when there is a blockage of blood supply to parts of the brain. Depending on the areas affected, this can bring about different forms of impairment.

When areas of the brain linked to vision are affected, an affected individual may develop poor vision and/or lose the ability to move the eyes properly as muscles of the eye and face may be paralyzed. Severe paralysis of the face prevents proper blinking, which leaves the eyes irritated and dry. A stroke can also involve a blockage of the veins or arteries that supply the retina (the light-sensitive back portion of the eye which enables visual perception); this is an emergency which can lead irreversible loss of sight.

Therefore, individuals who have experienced an episode of stroke should have routine visits with their eye doctor.

MEASLES: Measles infection is more common among young children, most of whom may not have acquired immunity to the disease yet. Like most diseases which show up during these formative years of life, the after-effects can be quite serious. Children deficient in vitamin A face a greater risk of severe ocular complications. Disease is particularly evident on certain areas of the body such as the inner and outer linings of the mouth (including the tongue), ears, nose and eyes. Hence, disease signs commonly begin with fever, body rash, runny nose and red, watery eyes. The eye’s outer coverings (including the conjunctiva and cornea) are often diseased in this condition. When the damage done to these important structures become severe, harm done may be irreversible; in this case, visually impairing scars can develop on the cornea. In rare cases, the disease may also cause some damage at the back of the eye known as the retina, where nerves that enable vision are present. In conclusion, home-management or self medication should be avoided for individuals, particularly children, who get infected with measles.

Special mention

AGE-RELATED EYE DISEASE: Being elderly is not a disease; rather, the process of aging brings about changes in the body’s nature which show up in the eyes as well. Generally, these aging changes modify the form of the body. For one, as skin elsewhere on the body becomes slack and wrinkles, so do the eyelids and facial musculature turn saggy. The eyelids not only serve to protect the eyes from foreign objects but also spread the tear film even over the ocular surface. Hence, when this structure turns slack, the tear film would not be spread evenly. This causes symptoms of dryness such as itchiness, irritation and grittiness. Such symptoms can be managed by an eye care practitioner who may prescribe eye drops that ease this form of discomfort.

The most common ocular complication of the aging process is the formation of cataract – a loss of transparency of the eye’s natural lens. This occurs when biological materials that make up the lens become denatured. Cataract causes persistent cloudy vision, mimicking the appearance of foggy conditions. Depending on the severity of this condition, an affected individual may become incapable of performing everyday tasks independently.

Another ocular complication of the aging process is age-related macular degeneration. This condition involves ‘aging’ changes which affect the macula- an area at the back of the eye which contains the nerve cells responsible for clear, daytime vision; including activities like reading, driving, sewing/stitching or any other form of detailed activity.

Being elderly also puts one at greater risk of diseases such as hypertension, arthritis etc; which as earlier mentioned, pose greater risk of developing vision problems. For this reason, it is advised that individuals above the age of 60 years get their eyes examined regularly.

   Well, that was the roundup of ten systemic diseases which can affect the health of your eyes. Hope you enjoyed it and learned a lot along the way too; including the benefits of regular eye examinations. Although the conditions listed above are just 10 in number, there are numerous other disease conditions which affect the eyes. So, I’ll health accompanied by visual symptoms warrants an eye examination to prevent serious problems.

Book an appointment with us today for your comprehensive eye examinations at: Centre For Sight Africa

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