“Everything about the eyes”

How the eyes work

All the different parts of the eyes work together to help you see.

First, light passes through the cornea (the clean anterior layer of the eye). The cornea is domed and bends light to help focus the eyes. Part of this light enters the eye through an opening called the pupil (PYOO-pul). The iris (the colored part of the eye) controls the amount of light that the pupil transmits.

Then light passes through the lens (clean inner part of the eye). The lens works with the cornea to properly direct light onto the retina. When light touches the retina (a layer of light-sensitive tissue at the bottom of the eye), special cells called photoreceptors transform light into electrical signals.

Tears also need eyes to function well.

Eye health

The eyes are complex organs. There are several parts that must work together to create a clear vision. Read on to get a basic overview of the anatomy of the eyes and learn about common eye conditions.

Part of the eye

Problems or disorders in any part of the eye cause many common eye conditions.


The cornea is a layer of transparent tissue in front of the eye that helps focus light.

Tear tubes

Tear duct openings are located in the upper and lower lids in the inner corner of each eye. Tears are secreted by the lacrimal gland from the outer eyelid above the surface of the eye. Tears keep the cornea lubricated and free of impurities. Tear ducts shed tears.

Iris and the disciple

(The colored part of the eye is the iris.) It is a set of muscles that control the pupil, and it is a hole in the center of the eye.

Lens and retina

The lens is behind the pupil. It focuses light on the retina, light-sensitive cells on the lower part of the eyeball.

Optic nerve

The optic nerve is a large bundle of nerve fibers attached to the lower part of the eye. Refractive errors

If the light is not focused properly, it causes blurred vision. Glasses, contacts, or surgery can generally correct refractive errors, which include:

nearsightedness (myopia), when distant objects appear blurred

hyperopia  (hyperopia), which appears blurred when approaching closed objects

presbyopia,  which is thought to be caused by a loss of flexibility in the lens of the eye due to aging.


Glaucoma is the increased pressure of fluids in the eye. This can cause damage to the optic nerve. Glaucoma is a common cause of blindness. ( Age, race and  family  history   important risk  factors. )


Cataracts are blackened lenses that cause blurred vision or discoloration. People with cataracts often report a “halo” of the surrounding objects they observe, especially at night. This condition is more common in older adults. Cataracts can be removed by surgery and the damaged lens replaced with an artificial one.

Age-related macular degeneration (AMD)

AMD causes blurred vision, especially in the center of the field of view. According to sources trusted by the Centers for Disease Control and Prevention, AMD is the most common cause of blindness and vision loss in people over the age of 65 in the United States.


Amylopia is commonly referred to as the “lazy eye.” This occurs when vision is not properly developed in the eyes and the brain begins to favor the eye with better vision.

This happens when it is forbidden to create clear images in one’s eyes during critical years from age to birth. The eye can be blocked by problems such as a drooping eyelid, a tumor, or improperly placed eyes (strabismus), which are inaccurate when the child is small.

It is essential for an ophthalmologist to evaluate a child whose views do not agree or who have vision problems to ensure that the diagnosis and treatment are correct.

Diabetic retinopathy

Diabetic retinopathy is damage to the retinal vessels caused by diabetes. It causes blurred or dark spots in the field of view and can eventually lead to blindness.

The best way to avoid these vision problems is to keep your blood sugar levels under control and see your ophthalmologist for an extended eye exam every year. Proper care can reduce complications.

Retinal detachment or rupture

When the retina separates from the lower part of the eye, it is called the detached retina. It causes blurred vision and partial or complete loss of vision and should be treated as an emergency medical service.

Dry eye syndrome

Dry eye is a lack of tears. This is usually caused by problems with the formation of tears, tear ducts or eyelids or is a side effect of some medications. This condition can cause pain and blurred vision.

And take away

The eyes are complex and it is important to know the different parts and how they work.

Knowing how the parts work will help you identify vision problems and symptoms of common eye conditions so you can start early treatment and maintain eye health.

Age-related macular degeneration

Macular degeneration

Macular degeneration, often called age-related macular degeneration (AMD), is an eye disorder associated with aging and leads to acute and impaired central vision. Central vision is necessary for clear vision of objects and for common everyday skills such as reading and guiding. AMD affects the macula, the central part of the retina that allows the eye to see small details.

Wet AMD is a situation where an abnormal blood vessel behind the retina begins to grow under the macula, eventually leading to a leak of blood and fluids. The first sign of a wet AMD is that the straight lines look wavy.

Dry AMD is when the macula dilutes and gradually blurs central vision during the aging process. Over time, due to less macular function, central vision is gradually lost in the affected eye. The dry AMD usually affects both eyes. One of the first most common symptoms of dry AMD is drusen.

Small yellow or white deposits form under the retina. They often occur in people older than 60 years. The presence of small bruises is normal and does not cause vision loss. However, the presence of large and numerous drusen increases the risk of developing advanced dry AMD or wet AMD.

It is estimated that AMD affects 1.8 million Americans 40 years of age and older, and another 7.3 million large users are at significant risk of developing AMD. The number of people with AMD in 2020 is estimated at 2.95 million. AMD is a major cause of permanent reading impairment and fine or near vision in people over 65 years of age.

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