This video lecture covers ocular motility, specifically the difference between tropias and phorias. This is a simplified approach to detecting strabismus and documenting your findings. I’ve created an animatronic set of eyes out of cardboard to simulate these findings!

## Download

TropiaVsPhoria.m4v (139 mb)

## Screen Captures and Notes:

**Tropia Definition:**

Misalignment that is always there, even when both eyes are open and attempting

to work together. Large angle deviations are obvious. If small angle, you can

detect it with the Cover-Uncover test.

**Phoria Definition:**

Misalignment that only occurs some of the time, such as when the synchronization

between the eyes is broken by covering one eye. You can “break fusion” using

the Cross-Cover test.

Wow! Great explanation and animations!

Thank you Dr.Root

Your presentation is very helpful and simple as you usually do..

keep good work up and thanks again.

Thanks, Dr. Root.

Thank you Dr Root for your good and scholar presentation

good job

Great explanation

Dr.root a salute to u.wat an amazing job you have done.sir please continue to do this noble work by giving out these great informative and intereting lectures.thank you.hope to meet you some time in the future.thank you again

Great explanation and we enjoyed your lecture! Thank You

it is more than great video.you simplified many obstacles.thank you very much.

well i am just 14 years old and i dont get the explnation so lets hope next time

GREAT PRESENTATION THANK YOU DR ROOT

This was a great works and did a a tremendous help in teaching our student to understand this topic.

Hi Dr.Root

In the frist I want say thank you for your lectures

I have a question when we do the glasses to the patient we but prism in front of the natural eye or in front of the eye in which have tropia

Thank you

Thank you very much for your nice videos

thank you for you intrsting lecture but we need more lecture to cover all point about squint

superb!!!! Simply the best

Thank you so much.This’s very usefull for my study.

simplified the basics of squint.can u add some more lectures about squint.

u r great sir. all dr teachers should like u. thank u very much

Thanks so much! Great video for distinguishing between phoris and tropias.

Dr.Root

I learnt retinoscopy prety well with the help of your video and now the difference between Tropias and Phorias. Your explanations are simply simple. Thank you so much.

Sir, I wish to see a animated/live demo of usage of JCC (Jackson’s cross cylinder).

Thanking you once again.

thank you very much for your excellent video

Wow great video! Thanks

I would like to point out that a you defined a tropia as a misalignment that is always there. A trope can be also be intermittent, and therefore not always there.

@ Aaron:

Thanks for the feedback. I purposefully kept the definition of tropia as simple as possible. You are correct, in that you can also have an “intermittent tropia.” You can also have an alternating tropia, convergence-related tropia, and many other “types” of tropia/phoria depending upon how you like to name things.

When I put this presentation together, I felt it safer to avoid these nuances. I feared that discussing the intermittent nature of phorias/tropias would muddy the waters for the beginner and make the primary difference (between phoria and tropia) that much harder to grasp.

Thus, the definition I used is simplified … but still useful and valid for a beginner. Perhaps I’ll go into further detail in a future lecture. Thanks!

Tim Root

Thanks a lot .

Thank you!! I am a medical student and i now can totally understand tropis and phoria. hope i can make a Mandarin version in the future. Love your work~~!!

i will like to know the difference betweent phorias and tropias.thank u.

Hi Tim,

Great lecture, very easy to follow. however i am a little confused as to what you meant by a ‘right esophoria’ (mentioned towards the end of the lecture). Ive always understood phorias being a bilateral misalignment of the visual axis, however you could have an esophoria which breaks down to alternating esotrpia…then breaking down further to maybe a right esotropia as the eyes fatigued with time.

superb sir. amazingly simple presentation.

thank u so mch sir ..ur lectures r so marvellous

.They should be a part of the curriculum..

Thanks alot Dr Root.

You really equiped me with ellaborate informations.

Keep it up.

great presentations,you have fans in morocco

you are the best sir…always checking this site…please keep adding more…we tuely love your efforts

thank you so much DR ROOT &thanks GOD you are there for me am so greatful for your effort to make ophthalmology easier for us.

Amazing! Thank you sooooooooooooooooooooooooooo much!

Por favor… que sea en español!

Excellent simple tutorial

THANK YOU SO MUCH DR. ROOT

Thanks alot Dr Root . Iam medical student from egypt and I love your videos alot

keep it up dr root

what are the yoke muscles involved in dextroelevation?? please give some explanation as well

A special thank you Doc & two thumbs up … YOU ARE GREAT.

its a very nice video& lecture that i appreciate………

thank you for the care and Great work Doc we appreaciate your concern keep Posting them

excellent,outstanding

I have just returned to COA after 15 years away. Your videos have been a lifesaver!!! Thanks so much for posting these, I’ve watched every single one!

fantastic videos lot of conceps cleared thnks

I’m a optometies in china,I love your thinking,it help me know something more easy.I try to translate your lectur. I think it will be very helpful.I hope that you can give me some advice。

Thank you root for the lecture and video simplified

Amazing video Dr Root! Big fan from Australia, loving your work!

it was a nice video . thank you so much to upload this video..

Do u incorporate a prism into a spectacle,is it possible? And how is it done. Thank u

thanks Dr.Root the lecture was very helpful and useful

Simplicity is a difficult art and you complete mastery of it.

Thank you

hi may I ask how does our eyes synchronize and how does a cross-cover test break the fusion?

Thanks for giving us such an difficult topic in a simple and easy way, otherwise it was not clarified to me since last two years in ophthalmic classes

thank you very much

Hi Dr Root ,

amazingly simplified explanation …

thank you

keep posting !!!