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Types of Eye Diseases

Instructor: Ashli Wilson

Ashli has a Master's Degree in Biology and has taught biology at different grade levels including college, elementary, and middle school.

This lesson gives a description of the eye and examines its anatomy. Also, this lesson will discuss diseases affecting vision as well as the parts of the eye the diseases impact.

Structure of the Eye

Lucy is a 30-year-old writer and is in good health. She spends a lot of time in front of the computer due to her work. Lucy starts experiencing blurry vision and headaches. What eye condition or disease could Lucy be suffering from?

Before we can discuss possible diseases that Lucy is suffering from, let's first discuss the structure of the eye. The eye is approximately one inch in diameter. The function of eyes is to relay images to our brain for interpretation.

Human Eye Diagram
Human Eye Diagram

The cornea is the part of the eye that allows in light. The pupil controls how much light is let into the eye by restricting and dilating. The pupil restricts when you are outside on a bright, sunny day to let less light into the eye and dilates when you walk into your room and no lights are on. The colored part of the eye is the iris, which encircles the pupil.

The lens acts like a mirror and changes the direction of the light. It also helps to concentrate the light. After light is let into the eye, the light is focused on the retina by the lens and an image is created. The optic nerve then transports images to the brain and receives messages from the brain.

Now let's take a look at different eye diseases and conditions and discuss possibilities of which eye ailments could cause Lucy's symptoms.

Eye Diseases that Impact the Lens

Cataracts occur mostly in the elderly and is caused by proteins clumping together on the lens. Cataracts cause the lens to become cloudy, resulting in blurry vision and eventual loss of sight. Common symptoms are being blinded by oncoming headlights at night and seeing halos around lights. Treatment includes surgery to remove the lens or implantation of a lens behind the cornea.

Glaucoma is a group of diseases that is caused by pressure due to the buildup of fluid in the eye. The pressure then causes damage to the optic nerve. The most common form of glaucoma is open-angle glaucoma. Typically, glaucoma is undetectable in the beginning stages but as the disease progresses, symptoms include loss of peripheral vision, mild eye pain, and a halo around the eye. Treatment includes prescription drugs and surgery. All treatments aim to reduce the amount of fluid in the eye. With treatment, loss of vision can be prevented.

Eye Diseases that Affect the Retina

Age-related macular degeneration (AMD) is caused by aging and typically occurs with people over the age of 60. There are two types of AMD: wet and dry. Wet AMD causes abnormal blood vessels to grow in the macula or center of the retina, resulting in damage to the macula. Dry AMD causes cells in the macula to die. Symptoms people with dry or wet AMD experience loss of central vision, problems reading, and lines appear to be wavy. There is no known treatment for dry AMD, and treatments for wet AMD aim to slow vision loss through prescription drugs that prevent blood vessels from growing.

Diabetic retinopathy occurs in people with diabetes who have high blood sugar over long periods of time. High blood sugar damages blood vessels in the retina. The damage to the blood vessels causes bleeding and scarring to the retina leading to blindness. Symptoms include seeing red spots, double vision, pain, and pressure in the eyes. Treatments for diabetic retinopathy include controlling blood sugar but if the disease has progressed laser eye surgery is recommended to reduce blindness.

Other Ailments Common in the Eye

Bacterial conjunctivitis (also known as pink eye) is a common eye infection that is highly contagious. Bacterial conjunctivitis is caused by bacteria entering the eye, causing inflammation on the surface of the eye. Symptoms of pink eye are itchy, watery eyes, eye swelling, and eye redness. Pink eye is easily treated with eye drops and ointment.

Refractive errors is very common and is caused when light is not correctly refracted onto the retina. There are two types of blurred vision, which are commonly known as nearsightedness (only things that are near can be seen correctly) and farsightedness (only things that are far away can be seen correctly). Treatment includes wearing glasses or contact lenses to correct vision.

Eye strain is extremely common and is characterized by burning and tight eyes, blurry vision, and headaches. Eye strain is typically caused by reading for long periods of time and prolonged use of electronics, including computers and cell phones. Treatment for eye strain is to rest the eyes and make sure proper lighting is utilized. Wearing glasses when reading or using electronics is another treatment.

Determining the Type of Eye Condition

Let's try to determine Lucy's problem from the information we've just gone over. Lucy suffers from blurry vision and headaches. We can rule out some conditions based on her symptoms and what we know about Lucy.

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