Wide-eyed Wonder: an artist's musings on three-dimensional vision

Some are color blind. I am stereo blind.

3D gaming and esophoria risks

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In a Wall St. Journal article last Friday, it was reported that a professor in the Department of Ophthalmology, Osaka University Medical School, Japan will be studying whether children with esophoria, the tendency for the eyes to turn inward, will become at risk of more turn-in with prolonged 3D gaming.

Takashi Fujikado, a visual-science professor at Osaka University’s Graduate School of Medicine, is starting research on whether children afflicted with esophoria, who are constantly making extra effort to prevent their eyes from becoming cross-eyed, may find it difficult to return the eyes to normal position after watching 3-D images for a long period of time.

When a 3-D image pops out from a screen, it draws the eyes inward to focus on an object that appears closer. This may affect children six years old and younger because their eyes, still under development, are more sensitive to such stimuli, he said.

Children with such a condition are rare but it is difficult to determine how many there are, Mr. Fujikado said, because esophoria doesn’t necessarily have symptoms.[1]

I have a hunch that what Dr. Fujikado is looking for is whether the esophoria may develop into an esotropia, where an eye constantly or alternately turns inward. Alternating esotropia is the strabismus I mysteriously developed as a child, unknown to my parents and undetectable in photographs.

Visitors try Nintendo's 3DS players at Nintendo World 2011. —Bloomberg News

Esophoria is not a form of strabismus. It is “A muscle condition in which, when both eyes are open, each eye points accurately at the target. However, upon covering one eye the covered eye turns inwards. Also known as over-convergence.”[2]

Esophoria can be picked up during an eye exam with a cross-cover test that breaks fusion. Watch the differences between exotropia and exophoria here. With esotropia and esophoria, the deviating eye would snap back into alignment from the nose, not the ear. (Note the extreme solution of surgery is for tropias of a certain kind that cannot be corrected with vision therapy or orthoptics.)

Unlike esotropia, fusion is possible (with esophoria) and therefore diplopia (or seeing double) is uncommon.[3]

Donald J. Getz, OD, FCOVD, FAAO explains another sign of esophoria [4]

“… a child with esophoria sees things smaller than what they actually are. In order to see an object properly, it is necessary to make the object larger. The only means at the disposal of the child to make it larger is to bring it closer. Eventually, the child is observed with his head buried in a book… ”

Photograph: Frank Baron

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