Our eyes are a fragile part of our body. Good eye health and eye care help protect sight, prevent common eye disorders, and treat eye problems early. So how does the eye work? And what common eye disorders exist?
The eye works much like a camera. Light passes through a lens (the cornea) and focuses lights, colors and shapes on the retina. The retina then registers these images and sends them to the brain. To focus vision on things close up, far away and everywhere in between, you simply contract and relax the muscles that make up the thin vascular tissue which secretes transparent liquid within the eye (ciliary body). This function allows us to see objects throughout our range of vision. Other parts of the anatomical eye include the following:
cornea - the outer part that focuses light located at the front of the eye
iris - the colored part of the eye that regulates the amount of light entering the eye
lens - the clear part of the eye behind the iris that helps to focus light and images on the retina
macula - the yellowish central area of the retina, which is rich in cones that mediate clear, detailed vision
optical nerve - a bundle of one million+ nerve fibers that carries visual messages from the retina to the brain
pupil - the opening at the center of the iris that controls the amount of light that can enter the eye
retina - a light-sensitive tissue lining at the back of the eye that converts light into electrical impulses that are sent to the brain through the optic nerve
Eye diseases and conditions
Sometimes the shape of your eye doesn't bend the light properly, and this can lead to common vision problems like nearsightedness and farsightedness. Other time, more specific health conditions can cause eye problems. Here, we examine the most common eye diseases and define each:
Age-related macular degeneration (AMD) - AMD is a disease that blurs central vision. Dry AMD occurs when light sensitive cells in the macula break down and central vision gradually becomes blurred or lost. Wet AMD occurs when abnormal blood vessels behind the retina grow under the macula, leaking blood and fluid that cause the macula to move from its normal anatomical position.
Eye allergies - This condition is often unidentified and occasionally left untreated. The most common symptoms of eye allergies are itching, redness, watery eyes and lid swelling. Eye allergies can also lead to redness of the eyelids, blurred, hazy or unclear vision, eye swelling, or a feeling like something is in the eye.
Astigmatism - Astigmatisms occur when the cornea is slightly irregular in shape, causing images to focus on more than one point in front of, or behind the retina. Images at all distances may be blurry, resulting in the overall inability to see clearly.
Corneal ulcer - Ulcers of cornea occur when the cornea is infected by bacteria, virus, fungi or amoebae. Ulcers are also caused by corneal abrasions and poor contact lens hygiene. Symptoms of corneal ulcer include eye pain, redness, itching and burning, white patch on the cornea, impaired vision, increased tearing and sensitivity to light.
Cataracts - A cataract occurs when the eye's lens becomes so clouded that it keeps light and images from reaching the retina. This can lead to image blurring, glare, double vision and decreased night vision. Cataract clouding is often caused by aging, but it can also stem from eye injury or certain diseases.
Conjunctivitis - Conjunctivitis is an infection of the inner eyelid membrane that can be caused by a virus or bacteria and is characterized by red, itching, watery eyes with a burning and scratchy feeling. The infection may also cause blurred vision and sensitivity to light.
Diabetic retinopathy - Diabetic retinopathy is a complication that occurs in patients with type 1 and type 2 diabetes as a result of the condition damaging the blood vessels inside the retina. If the damaged vessels leak blood, severe vision loss and even blindness can occur.
Dry eye - Dry eye (burning, scratching and stinging), is caused by a lack of tears. Tears provide natural lubricant to cleanse the eye and wash particles away. Dry eye is often caused by aging, dry environment, sun exposure, allergies and smoking and can be treated with artificial tear drops or ointment.
Glaucoma - Glaucoma is a group of diseases that can damage the eye's optic nerve, resulting in vision loss or blindness. Glaucoma is caused by increased pressure on the eye from increased eye wayer production or decrease eye water drainage. Glaucoma often develops with no symptoms and no pain, but left untreated, can lead to gradual loss of peripheral vision.
Hyperopia - Also known as farsightedness, this is a condition of the eye in which the cornea has too little curvature or the eyeball is too short, causing light entering the eye to focus incorrectly. This leads to blurred near vision.
Myopia - Myopia, or nearsightedness, is a condition that results in blurred distance vision. This occurs when the eyeball is too long or the cornea has too much curvature, causing light entering the eye to focus incorrectly.
Presbyopia - Presbyopia occurs when the eye loses its ability to focus on nearby objects. The lens of the eye loses its elasticity and the individual is no longer able to read, drive or perform other tasks requiring nearsightedness without the aid of glasses.
Usually, there are tell-tale signs of vision problems. But what are the signs and symptoms that you should look out for? Continue reading the next section for more information on vision problem symptoms.