If I test different people's’ eyes at 9am, 12pm and 3pm using a visual acuity test, then I believe that the test done at 3pm will have the worst results. 
This later test should garner the worst results because students have been focusing for the majority of the day and the eyes have a higher probability of being strained.
 

Should vision dramatically fluctuate throughout the day?
Vision should not dramatically fluctuate throughout the day as it can be a warning of serious medical conditions such as diabetes or hypertension. Blurred vision, spots, and strings or darkness in vision can be indicative of diabetic retinopathy, a disease that causes progressive damage to the blood vessels in the retina. Hypertension, a disorder in which the heart has to work harder to pump blood, can present itself through the eyes as sudden changes in vision while blood pressure is elevated. It is also possible to detect vascular issues through examination of the retina. The vascular system is the network of veins and arteries that carry blood and lymph fluid throughout the body. The retina is the part of the eye that focuses light and converts it to nerve signals so that the brain can interpret what is seen. When vascular issues occur, blood can be visible in and around the eye, clearly alerting that something is wrong. Diabetes presents itself through diabetic retinopathy, where high blood sugar damages the blood vessels in the retina, causing blurred vision and floaters in your vision. 

What are some common ocular disorders, diseases, and symptoms?
The most common ocular disorders are refractive errors, meaning that the shape of the eye affects how the light is focused onto the retina. People suffer from many refractive errors, but the most common are hyperopia, myopia, astigmatism, and presbyopia. Myopia is more commonly known as nearsightedness, where you can see more clearly up close, and is caused by an abnormally oval shaped eye. Another cause of myopia is an overly curved cornea, the clear protective cover on the front of the eye. Hyperopia, or nearsightedness, on the other hand, is caused by the eye growing too short or the cornea not being curved enough. Hyperopia is the opposite, where vision is clearer when looking at things far away.  Astigmatism is another very common eye disorder caused by an imperfection in the curvature of the cornea. With astigmatism, objects will be blurry from all distances rather than near or far. Finally, presbyopia is an ocular disorder affecting adults, beginning usually between the ages of 40 and 50 years old. Also known as “old age nearsightedness”, presbyopia occurs when the lens, an inner layer of the eye that helps focus, stops focusing light onto the retina. 

Eye hypertension indicator

What are some ways to improve vision issues?
While there is no way to completely correct things like myopia, there are methods to slow the progression. For example, special contact lenses that are made to slow the progression can slow it down by about 59%. In contrast, myopia slowing glasses only slow the progression by 43%. Things like cataracts, which is clouding of the lens of the eye, can be treated through cataract surgery which is widely available. The procedure involves removing the clouded lens and replacing it with an artificial lens. This lens is called an intraocular lens and remains a part of the eye. There is no alternative to cataract surgery. 

The left eye is an example of a cataract. It is clear
 which lens has become cloudy, obstructing vision. 

What causes eye strain?
Eye strain can be caused by many things, and each can differ from person to person. Perhaps the most prevalent cause of eye strain is technology. Digital eye strain is caused by reading off of a screen or watching a screen for large amounts of time. This is because when looking at a screen, a person's average blink rate goes down by almost half. This can cause dry eyes, blurred vision, teary or watery eyes, and headaches. These things are not permanent but will cause temporary discomfort if screen use is prolonged. Dehydration is another cause of eye strain that is less common. When dehydrated, the body uses the moisture it has to keep vital organs working, while the eyes don't have enough moisture to be properly lubricated. Prolonged eye strain has not been found to cause lasting effects on vision, but mild discomfort has been recorded. 

How are vision tests done?
There are many different vision tests taken during an eye exam, but the one most people think of is the visual acuity test. This is a test using a letter chart in which the patient reads the gradually smaller letters until they can no longer make them out. This test measures the sharpness or clarity at which you can see something at a certain distance. This test produces the common vision ratings out of 20. When someone has 20/20 vision, that indicates that they can read a set of letters from 20 feet away, that most people should be able to. 20/20 vision is considered to be average eyesight. It is possible to have a higher than average eyesight, with a vision percentage of 20/15 or any other where the first number is larger than the second. This indicates that you can see something clearly from 15 feet away ile someone with average eyesight will be able to read from 20. The second test that is quite important is the eye muscle movement test, during which the patient will be asked to follow an object such as a pen or pencil so that the optometrist can track your eye movements and detect any issues with the extraocular muscles of the eyes. The extraocular muscles control both the movement of the eye and the eyelids elevation.  

    Visual Acuity Test

How do glasses and contacts help people with vision impairments to see more clearly?
    Glasses come in 3 different types: concave, convex and cylindrical lenses. Concave lenses are thinnest in the middle and are used to treat myopia because the lens shape allows for the magnification of far away objects. This happens because the concave lens diverges the light rays, placing the image directly onto the retina rather than in front of it. Convex lenses, on the other hand, have the thickest part in the middle, thickening towards the edges. These lenses allow the light rays to converge at the retina instead of past it, correcting hyperopia. Cylindrical lenses compensate for an uneven cornea, allowing the light to be reflected onto the retina properly. They are uniform in thickness, not needing to put specific distances into focus. Contact lenses work slightly differently, as they lie directly on the eyeball rather than in front of it. They correct vision more seamlessly than glasses because they extend to peripheral vision and don't have the interruptions of frames and dirty lenses.  A contact lens still has the same basic principles as glasses, changing where the light rays converge to create a clear image on the retina. A contact prescription will not be the same as a glasses prescription because of the distance from the eyeball. 

Left- Uncorrected myopia                                            

Right- Myopia corrected with concave lens                                                                                                                                                  

Top- Uncorrected hyperopia

Bottom- Hyperopia corrected with convex lens

Top- Uncorrected astigmatism

Bottom- Astigmatism corrected by cylindrical lens

1. Measure the distance needed between the eye chart and chair
2. Have participant sit on thechair and face the letter chart
3. Participant covers right eye with eye cover and reads until the letters are too small
4. Record observations
5. Repeat steps 3 and 4 covering the left eye
6. Repeat steps 2-5 with other participants using the lysol wipe to sanitize the eye cover between participants
 

In my experiment, I tested the vision of 14 individuals over 3 periods of the day to see how their vision would change throughout the day. I was surprised to see how many people had large differences between the strength of their left eye and their right. 

It was also surprising how similar many individuals results were. I believe that this was due to the fact that some people had been in the same classes and doing the same work, ergo focusing the same amount. 

My hypothesis was correct, I had predicted that as the day progressed, subjects vision would deteriorate due to focusing. My results proved that for each eye, the average vision results got worse. 

Poor vision affects students in many ways, the most common consequence being a short attention span. This is shows how important it is to take breaks throughout the day to ensure visions is not impacted. Many students who have undiagnosed visual problems will become frustrated by tasks that are reading focused and lose motivation to complete them. Due to many aspects of education being reading-based, these students may find themselves performing worse in school and falling behind. My next steps with this experiment would use controlled lengths of screen time to see how much prolonged screen time affects vision and focus. 

Throughout my experiment I encountered one main source of error. It was an error on my part, in which I misunderstood the instructions on the chart. The individuals in my experiment were mistakenly placed twice as far away from the chart than they should have been, meaning that their results did not accurately show the quality of their vision. However, this did not impact my experiment as I was still able to see the changes in their vision. 

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I would like to acknowledge and thank the many people who came together to help me accomplish this amazing experiment. For starters, I would like to thank my mother, for being there every step of the way to help and support me. I would also like to thank the 14 students who helped me conduct my experiment. They are as follows. Ava Ahmed, Aamina Andrabi, Nicholas Bartas, Sofija Dojcinovic, Malak Elsinbawi, Avery Kosanovich, Dharma Medina, Lucas Pickering, Ally Rustad, Ashley Simpson, Chloe Simpson, Owen Skinner, Ella Sky, and Emilia Tait. Without them, none of this could've been made possible.