Feeds

How does a cross-eyed person's view differ from others?

Looking at life from another angle

New hybrid storage solutions

Also in this week's column:

How does a cross-eyed person's view differ from others?

Asked by Michel Durinx of Leiden, The Netherlands

The medical term for "crossed-eyes" is strabismus. Another medical term for it is heterotropia. But it goes by other popular names too including wandering eyes, squint eyes, and walled eyes. Walled eyes is often thought of as the opposite of crossed eyes.

Crossed eyes is when the eyes point inwards. Walled eyes is when the eyes point outwards. Strabismus is a chronic abnormality of the eye from the normal visual axes (ocular deviation). The the eyes don't point in the same direction.

Strabismos is Greek for "squinting". The type of strabismus is referred to as a tropia. Troupe is Greek for "turning". A prefix indicates the direction of the ocular deviation. So when one eye is rotated around its visual axis with respect to the other eye it is "cyclotropia". Cyclo is also Greek for "turning". When the ocular deviation is such that one eye turns inwards it is "esotropia" and when outwards it is "exotropia". When the ocular deviation is such that one eye turns upwards it is "hypertropia" and when downwards it is "hypotropia".

Eye muscles (extraocular muscles) bring the gaze of each eye to the same point in space. Strabismus occurs when there is a lack of coordination of these muscles. This results in poor binocular vision that affects depth perception.

Near or far-sightedness can result because the brain cannot fuse the two different visual images into one. In infancy, congenital strabismus can cause amblyopia. This is a condition in which the brain ignores input from the ocular deviating eye, although it is capable of normal sight.

Amblyopia is sometimes called "lazy eye". Sometimes when the infant's bridge of the nose is wide and flat and when there are skin folds in the corner of the eyes, there is an appearance of strabismus. This is called "false strabismus" or "pseudostrabismus". As the child grows, the skull develops, and the bridge of the nose narrows, the folds in the corner of the eyes go away. There is no problem with vision. The test for this involves the doctor shining a light into the child's eyes. The light's reflection off of the pupil should be in the same spot of each eye if there is no strabismus.

Stephen Juan, Ph.D. is an anthropologist at the University of Sydney. Email your Odd Body questions to s.juan@edfac.usyd.edu.au

Secure remote control for conventional and virtual desktops

More from The Register

next story
Thought that last dinosaur was BIG? This one's bloody ENORMOUS
Weighed several adult elephants, contend boffins
Boffins say they've got Lithium batteries the wrong way around
Surprises at the nano-scale mean our ideas about how they charge could be all wrong
Chelyabinsk-sized SURPRISE asteroid to skim Earth, satnav birds
Space rock appears out of nowhere, buzzes planet on Sunday
City hidden beneath England's Stonehenge had HUMAN ABATTOIR. And a pub
Boozed-up ancients drank beer before tearing corpses apart
'Duck face' selfie in SPAAAACE: Rosetta's snap with bird comet
Probe prepares to make first landing on fast-moving rock
Archaeologists and robots on hunt for more Antikythera pieces
How much of the world's oldest computer can they find?
prev story

Whitepapers

Providing a secure and efficient Helpdesk
A single remote control platform for user support is be key to providing an efficient helpdesk. Retain full control over the way in which screen and keystroke data is transmitted.
Top 5 reasons to deploy VMware with Tegile
Data demand and the rise of virtualization is challenging IT teams to deliver storage performance, scalability and capacity that can keep up, while maximizing efficiency.
Reg Reader Research: SaaS based Email and Office Productivity Tools
Read this Reg reader report which provides advice and guidance for SMBs towards the use of SaaS based email and Office productivity tools.
Security for virtualized datacentres
Legacy security solutions are inefficient due to the architectural differences between physical and virtual environments.
Secure remote control for conventional and virtual desktops
Balancing user privacy and privileged access, in accordance with compliance frameworks and legislation. Evaluating any potential remote control choice.