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The human eye is a sense organ that enables us to see things. The eye is composed of three parts – the outermost part comprising of the sclera and cornea; the middle part comprising of the ciliary body, iris and choroid; innermost part which is the retina. For normal vision to take place, the following sequence has to occur:

Light reflects off the object we are looking at and enter the eye through the cornea. It then passes through the aqueous humour to reach the lens. The lenses which have the ability to change in shape bend the light and focus it on the retina which is located at the back of the eye. The retina converts the light into electrical impulses which are then carried by the optic nerves to the brain. Ultimately, the visual cortex of our brain interprets the electrical impulses for us to see.

The eye works in a similar manner as a camera. Just as the shutter of a camera adjusts the amount of light entering the camera, so also the pupil and the iris together control how much light to let into the eyes. The lens of a camera focuses on objects far and near with the help of various mechanical devices. In a similar manner, the lens of the eye helps us to focus on objects.

Facts of Organ

Our eyes stay the same size

While our ears and nose grows, our eyes do not grow in size – they stay the same size from birth to death.

The human eye can differentiate 10 million colors

The human eye has the ability to differentiate between 10 million different types of colors.

Cornea is the only tissue that doesn’t require blood

Cornea is the only tissue in the eye that doesn’t require blood. In fact, the presence of blood can interfere with its function.

The eye is the second most complex organ in the body

Next to the brain, the eye is the second most complex organ in the body. It comprises of more than 2 million parts all of which synchronize perfectly to make our vision perfect.

We blink 25000 times in a day

We blink around 25000 times a day. This is to protect the eyes from foreign particles and to keep the eyes lubricated.

Black lemurs have blue eyes

Black lemurs are the only primates, besides humans of course, to have blue eyes.

Blue-eyed people share a common ancestor

All blue-eyed people share one common ancestor who lived 10,000 years ago near the Black Sea.

Our retinas see the world as upside down

Our retinas see the world as upside down; it is the brain which flips it and makes us see things as they really are.

Iris has 256 unique characteristics

As compared to a fingerprint which has only 40 unique features, the iris has 256 unique characteristics which is why retina scan are increasingly being favored nowadays.

Functions of Organ

Light detection

While each and every object reflects light, the human eye can only detect only a small range of this light called the visible spectrum. The cone shaped cells in our eyes help us see this light. This light is however a small band on the spectrum. The other portions of the spectrum have wavelengths which are either too small or too large for us to view with the naked eyes. Without any external aid, our eye can only see the colors of the rainbow.

Sense of balance

While the sense of balance in the body is the responsibility of inner ears, the eyes too play a small role in providing a sense of balance. Our visual system provides information to the brain about where the body appears in relation to the horizon. Loss of vision can alter balance and make us see things differently.

Production of tears

Another important function of the eye is to produce tears. Tears lubricate the surface of the eye and wash away the debris, hence an important component of maintaining vison. If there is a disturbance in the tear film, people experience eye problems such as burning, tearing, irritation and blurred vision. Too much tear production can also indicate a problem with the eyes.

Night Vision

The less the amount of light, the more difficult it is to focus on objects. The human eye is sufficiently equipped with specialized cells called rods that allow for night vision. Without the presence of rods, it would be impossible for us to see during the night. Rods help create extra focus on objects that radiate less light.


Anatomical Features:

The eye has many parts that must work together to produce clear vision:


The sclera is the white outer part of the eye that protects the eye from external injury. It consists of a dense network of collagen fibers that make it tough


The iris is the colored part of the eye. It has a round opening in the center called the pupil. The iris regulates the amount of light entering the eye by changing the size of the pupil.


The cornea is a clear window located in front of the eye which helps the eyes to focus. It acts like a camera lens by focusing light onto the retina at the back of the eye.


The retina is a light-sensitive sensitive tissue that lines the back of the eye. It comprises of millions of rods and cones also called as photoreceptors that detect light and turn it into electrical impulses. These electrical impulses are then sent to the brain by the optic nerve. Cones function well in bright light and help us to recognize color and detail. The rod cells help us to see in poor lighting.


The conjunctiva is a thin layer of tissue that covers the outer part of the eye.

Crystalline lens

The crystalline lens is a transparent structure that lies in between the vitreous humor and the iris. Depending on distant or close vision, the lens can change itself to fine tune the focus of light on the retina.

Ciliary body

The ciliary body helps the eye focus on an object by changing the shape of the crystalline lens. It also produces aqueous humour, the clear fluid that fills the front of the eye. When looking at a near object, the ciliary body contracts which causes the lens to thicken and focus closely. When looking at a distant object the ciliary body relaxes that causes the lens to become thinner.

Aqueous humour

The aqueous humour is a watery fluid between the crystalline lens and the cornea. It is produced by the ciliary body. It is the aqueous humour which provides nutrition to the corneal cells. It also maintains the pressure needed to inflate the eye.

Vitreous humour

The vitreous is a clear jelly that lies between the retina and the crystalline lens of the eye. The vitreous humour helps to keep the retina in place.

Food Tips


Tomatoes are highly rich in carotenoids, including lycopene that gives tomatoes their red color. Research has shown that lycopene prevent damage to the retina and other parts of the eye. Tomatoes are also rich in copper and vitamin C which re very good for the eyes.

Spinach, Kale, and other Dark, Leafy Greens

Spinach and other leafy greens are rich in antioxidants like lutein and zeaxanthin. These antioxidants absorb blue light, which is extremely harmful for the retina. These nutrients also help the eye in detecting contrasts better, so consuming foods which are rich in these antioxidants will not only improve vision, but also help maintain the long-term vision.


Like spinach and other leafy greens, egg yolks are also a good source of lutein and zeaxanthin. The nutrients present in eggs like Vitamin protect the eyes from dry eye syndrome and night blindness. Egg yolks which are a natural source of vitamin D also help in reducing the risk of ARMD.

Colored fruits and vegetables

Colored fruits and vegetables such as tomatoes, corn, carrots, strawberries, bell peppers, pumpkin and cantaloupe are very good sources of vitamins A and C. Carotenoids, the compounds that give these foods their distinct colors are known to decrease the risk of many eye ailments.


Legumes such as lentils, kidney beans and black-eyed peas are excellent sources of zinc and bioflavonoids. These components not only protect the retina but also lower the chances of developing cataracts and macular degeneration.


Nuts are rich in omega-3 fatty acids and vitamin E that boost eye health. Among nuts, pistachios are the most eye-friendly. They contain significant amounts of zeaxanthin and lutein and are also rich in vitamin E. The mono and polyunsaturated fats present in pistachios help in better absorption of carotenoids.


Salmon is one of the best sources of eye-healthy omega-3 fatty acids, which is known to protect against dry eye disease, macular degeneration and cataracts. Vegetarians can get their supply of omega-3s by taking supplements that contain flaxseed oil or black currant seed oil. Salmon is also a good source of vitamin D, which is known for its eye healthy benefits.

Olive Oil

A diet low in saturated and trans fats are known to prevent retinal diseases. The Mediterranean- style diet comprising of healthy fats such as olive oil, fish and plant-based foods is best for maintaining healthy vision. Olive oil being low in saturated fats and rich in monounsaturated fats is the perfect oil for a healthy eye.

Lifestyle Tips

Get regular sleep:

Our eyes are continuously working – it is therefore important that they get some rest. Sleeping well is good for the eyes as then they get to rejuvenate themselves. Further, during shuteye period they also get to clear out the irritants like dust and allergens from the eyes.

 Eat well for Good vision

Eating well is the key to good vision. Nutrients such as lutein, vitamin C, zinc and omega-3 fatty acids can ward off age-related vision problems. Eating a well-balanced diet of leafy greens, citrus fruits and omega -3 rich foods will not only lead to good eye health but also reduce your chance of getting type 2 diabetes which is one of the leading causes of blindness.

Wear Sunglasses

Too much exposure to UV rays makes one more likely to get cataracts and macular degeneration. Wearing the right sunglasses can protect the eyes from the sun’s damaging rays. Sunglasses that block around 99 % - 100 % of both UVA and UVB rays should be used for optimum protection.

Use Safety Eyewear

If your job involves working with hazardous materials always wear safety glasses. Certain sports like ice hockey, lacrosse, racquetball etc can lead to eye injury. Wearing eye protection gears such as helmets or sports goggles can protect the eyes.

Take frequent breaks to avoid eye strain

Looking at a computer screen for long periods of time can cause considerable strain on the eyes causing blurred vision, trouble focusing, headaches, dry eyes, neck and back pain. Therefore, after working at the computer for 20 minutes, at least take a break of 20 seconds. This will enable you to maintain your eye health.

Visit Your Eye Doctor Regularly

Everyone should get their eyes tested regularly. Eye exams can help find out certain diseases which have no symptoms such as glaucoma. Diagnosing a disease early on can help cure it better. Depending on one’s eye care needs, one can either visit an ophthalmologist or an optometrist for an eye test.

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