There are many different diseases that can affect the eye only and impair vision to varying degrees. Sometimes diseases involving other organs or even the entire body may also affect the eyes. These diseases can cause damage to the eye or eyelid tissue, the muscles that move the eye, and/or the nerves that control the eye or are responsible for vision. Depending on the condition and its severity, these diseases can even lead to blindness.
“Non-Eye” Diseases that Cause Eye Damage
As with any part of the body, there are conditions that specifically affect the eye and affect vision. This may include conditions like conjunctivitis due to an infection, glaucoma cas a result of increased pressure within the eye or cataracts where the lens of the eye becomes cloudy. These conditions are limited to the eye and are therefore known as eye diseases.
In some of the conditions discussed below, the eye is not the only organ or even main organ that is affected. Instead the eye may be involved as a complication of the primary condition or the eye may be affected alongside with other parts of the body. Some of these causative conditions, like diabetes and high blood pressure, are common and widespread public health concerns which can eventually progress to blindness.
One of the common conditions that eventually affects the eyes is diabetes. This eye condition is known as diabetic retinopathy. With diabetes becoming more prevalent globally, the rise in diabetic retinopathy is understandable. The exact way in which diabetes affects the eye is not fully understood but it appears to be due to changes in the tiny blood vessels of the eye that arises with diabetes.
Read more on diabetic retinopathy.
The vision symptoms in diabetic retinopathy varies. It may include floaters, spots in the visual field, blurred vision, dark areas in the visual field, problems with perceiving color and vision loss. Eventually it can lead to blindness. The symptoms of diabetes will also be present if poorly managed. This includes excessive thirst, frequent urination, fatigue and changes in body weight. Diabetic retinopathy usually affects both eyes at the same time.
2. High Blood Pressure
Another health problem globally that can also affect the eyes and vision is hypertension (high blood pressure). In chronic hypertension, there is damage to the tiny blood vessels in the eyes in a similar way to diabetes. This eye complication due to high blood pressure is known as hypertensive retinopathy.However, even a sudden increase in blood pressure for a short period of time (acute) can also affect vision and even damage eye structure like the optic disc.
Hypertension is often referred to as the silent killer because there are little to no symptoms of elevated blood pressure. Therefore a person may not be aware of long term hypertension without routine screening or until complications like retinopathy arise. People with both hypertension and diabetes are at a much higher risk of retinopathy with greater chances of permanent blindness.
3. Vitamin A Deficiency
Vitamin A deficiency is known to lead to night blindness where the ability to see in low light levels is impaired although ther is not a complete loss of vision as the name may suggest. However, this nutritional deficiency may affect the eyes and vision in a host of ways. This can even lead to blindness in severe cases that are not treated and managed properly.
In addition, vitamin A deficiency can cause dryness of the eyes, thickening of the conjunctiva and cornea as well as ulcers (open sores) in the cornea. Most of the time vitamin A deficiency is due to inadequate intake of the micronutrient through food. However, it can sometimes arise with certain diseases of the gastrointestinal tract like inflammatory bowel disease (IBD), pancreas, gallbladder and liver.
Read more on nighttime eye problems.
4. Sickle Cell Disease
Sickle cell disease, also known as sickle cell anemia, is an inherited disorder where the red blood cells are abnormally shaped, rigid and sticky. These blood cells can clump together and obstruct small blood vessels like those in the eye. It impairs oxygen supply to the retina thereby causing damage of the retinal tissue.
Since the retina is the part of the eye responsible for vision, sickle cell disease affecting blood flow to the retina can lead to vision loss. This can also cause the retinal tissue to become detached which may lead to permanent blindness. Sickle cell retinopathy occurs slowly but sometimes there may be sudden onset blindness due to sickle cell disease.
Rosacea is known as a skin condition where parts of the skin, particularly on the face, are abnormally red. However, it can also affect other organs like the eye. This condition is known as ocular rosacea and is common among people who have rosacea. The cause of rosacea as well as ocular rosacea is unknown but tends to be due to a combination of genetic and environmental factors.
6. Sjogren Syndrome
Sjogren syndrome is an autoimmune disorder where the immune system attacks certain tissues and organs. In Sjogren syndrome, the immune system targets certain glands like the salivary glands and tears glands. This prevents these glands from producing and releasing their respective secretions thereby leading to symptoms like dry mouth and dry eyes. The eye dryness can cause a host of eye symptoms and visual disturbances. It can also increase the risk of certain eye conditions, like infections, which can have devastating and even permanent eye complications.
Shingles or herpes zoster is where the chickenpox virus becomes reactivated years and even decades after an initial chickenpox infection. Most of the time it is thought to cause a skin rash and pain since the reactivation of the virus affects nerves. The torso and head are commonly affected sites.
In opthalmic shingles, also known as herpes zoster opthalmicus, a nerve supplying the eye may also be affected. Apart from pain and rash around the eye, opthalmic shingles can also affect the lining over the eyeball (conjunctiva) as well as superficial and deep eye tissue, resulting in keratitis and uveitis respectively.