Eye fun

Online eye tests

Color vision test

About 8% of males and 0.5% of females are classified as having defective colour vision whether it is one color, or a color combination . This is moslty genetic in nature, but can also occur because of some eye, nerve, or brain damage. Males are at a greater risk of inheriting the condition due to it being passed on via the X chromasome. Due to females having two X chromasomes , if they inherit a normal X chromosome in addition to the one which carries the mutation, they will not display the mutation.

Color blindness may be partial (affecting only some colors), or complete (affecting all colors). Complete color blindness is very rare. The term Color blindness itself is misleading if taken literally, because colorblind people can see colors, but cannot make out the difference between some couples of complementary colors. Red/Green color vision deficiency is by far the most common form, about 99%, and causes problems in distinguishing the difference reds and greens.

The Ishihara Test

The most commonly used test to detect color vision deficiencies was developed by the Japanese ophthalmologist Shinobu Ishihara. While working at the Military Medical School he was asked to devise a test to screen military recruits for abnormalities of color vision. His assistant was a colorblind physician who helped him test the plates. A collection of 38 plates filled with colored dots build the base of this test. The dots are colored in different shades and a number is hidden inside with shades of another color.

Ishihara

The existence of color vision deficiencie is usually established after a few plates, the testing of the full 24 plates gives a more accurate diagnosis of the level of severity an individual suffers from the color vision defect.

In the above plates you should see the numbers: 74, 6, 12, 42, 2

The most commonly used test to detect color vision deficiencies was developed by the Japanese ophthalmologist Shinobu Ishihara. While working at the Military Medical School he was asked to devise a test to screen military recruits for abnormalities of color vision.

Dominant eye test

Eye dominance or ocular dominance, is the tendency to prefer visual input from one eye to the other. Both hemispheres control both eyes, but each one takes charge of a different half of the field of vision, and therefore a different half of both retinas.

Approximately two thirds of the population is right-eye dominant and one third left-eye dominant; however in a small portion of the population neither eye is dominant.

You can download the Deakin Dominanat Eye test here (800k pdf)

Dominant eye test

Instructions:

Step1
Print the Deakin Optometry Dominant Eye Test page on your printer

Step2
Cut out the small square in the centre of the page

Step3
Hold the page up at arms length

Step4
With both eyes open focus on a stationary object

Step5
While focussing on the object, slowly bring the paper closer
until it touches your face

Step6
The eye which you have over the opening is your
dominant eye

Eye dominance or ocular dominance, is the tendency to prefer visual input from one eye to the other. Both hemispheres control both eyes, but each one takes charge of a different half of the field of vision, and therefore a different half of both retinas.

Visual acuity

Snellen chart

Visual acuity (VA) is acuteness or clearness of vision, which is dependent on the sharpness of the retinal focus within the eye and the sensitivity of the interpretative faculty of the brain. The Snellen eye chart was first designed by a Dutch ophthalmologist, Herman Snellen in 1860s.

How to use the eye chart:

Due to difference in monitor sizes, the best way to do this test is to print the chart onto an A4 page.

Click here to download a PDF version ready to print(83k pdf)

The Snellen Eye Chart is read while standing 2.9 meters (9.5 feet) from the chart. Be sure you are in a room that is well lit

Test one eye at a time By covering the other eye with your hand. The lowest line that you can read correctly is your visual acuity.

Visual acuity is the clearness of vision, which is dependent on the sharpness of the retinal focus within the eye and the sensitivity of the interpretative faculty of the brain.

Illusions

Lilac chaser

Lilac chaser

The illusion was invented by Jeremy Hinton some time before 2005. He stumbled across the configuration while devising stimuli for visual motion experiments. In one version of a program to move a disc around a central point, he mistakenly neglected to erase the preceding disc, which created the appearance of a moving gap. On noticing the moving green-disc afterimage, he adjusted foreground and background colours, number of discs, and timing to optimise the effect.

Instructions:

Stare at the central cross.

You will see a greenish colour disc wherever the pink disc has disappeared.

Eventually, if you stare long enough, the pink discs will also disappear and you'll just see only a moving green disc.


Lilac chaser icon

Lilac chaser is a visual illusion, also known as the Pac-Man illusion. It consists of 12 lilac (or pink), blurred discs arranged in a circle (like the numbers on a clock), around a small black, central cross on a grey background.

Rotating snake illusion

Most observers see the illusion easily when reading text with the illusion figure in the periphery. Motion is consistently perceived in a dark-to-light direction. The shading in the image combined with the continuous random movement in our eyes, generate the movement illusions.Rotsnake

A famous example of Professor Akiyoshi Kitaoka's rotating snake illusion. The shading in the image combined with the continuous random movement in our eyes, generate the movement illusions.

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