Ocular Deviations

in StemSocial3 months ago

Greetings to all and sundry,

It is another beautiful day today and a privilege to have this opportunity to come your way once again with another discussion concerning our eyes. As a licensed and practicing Optometrist based in Ghana i see a lot of conditions everyday that i believe people ought to have some general knowledge about to help them do the needful before things get out of hands.


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A lot times patients would only come in when they realize that a condition is becoming worse or that their vision is getting seriously affected, sometimes they are lucky to have their vision saved as extreme measures are put in place towards treatment, unfortunately in some cases vision lost cannot be gained back and so we ought to be particular about our ocular health and do well to visit the Optometrist as soon as we notice anything regarding our eye.

That said, for today we would be talking about ocular deviations and i hope that you would get to learn a thing or two from the discussions, also, do feel free to ask questions or further clarifications.


When we talk about deviations of the eye we mostly look at two things either phorias or tropias. These would be talked about in detail in the subsequent chapters however, deviations of the eye just as the name suggest is a condition or situation where the eyes are misaligned such that one may appear to have deviated inwards or outwards.

The term "eso" is used to describe inward deviations whereas the term "exo" is used to describe outward deviations. These deviations or misalignment of the eye may come about as a result of physiological anomalies or anatomical anomalies.


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In terms of physiology we look at the functions of the eye which in one way or the other end up causing the eye to be deviated. A common ocurrence has to do with refractive errors where myopes tend to have outward deviations and hyperopes inward deviations as a result of over accomodation. A myope can still have eso deviation and vice versa for hyperopes too.

In terms of physiology the deviation may also be attributed to our vergence reserve (the total power of the eye to either convergence or come closer together for the purpose of vision or open up) not been sufficient for the work demand of the eye at any particular point in time. This may present variety of symptoms in patients which could be quite uncomfortable, a situation known as asthenopia.

In terms of anatomy, deviations set in when there is an anomaly with the extraocular muscles of the eye that controls our eye movements. This may come about as a result of a pathology or an anomaly with their growth. Anatomical cases normally warrant surgical intervention to correct whereas physiological cases may be corrected by an orthoptics or a binocular vision specialist by means of lenses or therapy.

Phorias and Tropias

So as i was saying deviations may be categorized as phorias or tropias, when we say phoria we are basically talking the form of deviation which is hidden in the eye. Thus, the eye is misaligned alright however it is not conspicuous when looking directly at the person or patient. Individuals with phorias may have their deviations show up every now and then when they are stress or exhausted and it mostly noticed by their peers or guardians.

The person may however tell you that they don't see anything when they look in the middle, this is because the eye is putting in so much effort to correct the deviation thus resulting asthenopia. Such individuals may have difficulty doing near work for quite a while or difficulty with distance work depending on their deviation. They may also report with headaches and intermittent blurry vision.


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Diagnosing requires the use of special equipment at the hospital for the deviation to show itself and for its magnitude to be measure accordingly.

Tropias however are manifest deviations. Another name for tropia is strabismus. One can easily tell that there is a misalignment between the two eyes without needing any case history or special equipment for that. The person or patient can easily confirm that they see their eyes deviated inward or outward when they look inside the mirror.

Most strabismus cases tend to be anatomical in nature and may warrant surgical intervention however there are some that are also physiological in nature especially in kids with high refractive errors. Kids with exodeviations having myopia can be over corrected to help with the misalignment whereas those with hyperopia having eso deviations can also be over-corrected to help with the alignment.

Management of Ocular Deviations

It is of utmost importance that noticing any ocular deviation whether it be intermittent or consistent be report to your Optometrist for further investigation and treatment. Ocular deviations can easily result in Amblyopia if not dealt with, it could also help lead to the diagnosis of refractive errors which could have a lot of detrimental effect on a child's education if left untreated.


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Just as mentioned earlier management procedures may include the use of lenses, therapy or surgery however you should not be dismayed as tech has made so many things in healthcare easier and less complicated now. The most important thing that i wish for you to do is to seek the right consult as soon as possible.


The eye is such a delicate and beautiful instrument that we ought to pay a lot more attention to it and be particular about its health. It is our window to the beautiful sceneries of this world after all and remember that sight lost may not be attainable.


Thank you for your time and for reading. I wish you all the very best and i look forward to another session with you all. Stay safe.

Further Reading

Kommerell G, Kromeier M, Scharff F, Bach M. Asthenopia, Associated Phoria, and Self-Selected Prism. Strabismus. 2015;23(2):51-65. doi: 10.3109/09273972.2015.1036080. PMID: 26158471..

Ticho BH. Strabismus. Pediatr Clin North Am. 2003 Feb;50(1):173-88. doi: 10.1016/s0031-3955(02)00108-6. PMID: 12713111.

Hashemi H, Pakzad R, Nabovati P, Azad Shahraki F, Ostadimoghaddam H, Aghamirsalim M, Pakbin M, Yekta A, Khoshhal F, Khabazkhoob M. The prevalence of tropia, phoria and their types in a student population in Iran. Strabismus. 2020 Mar;28(1):35-41. doi: 10.1080/09273972.2019.1697300. Epub 2019 Dec 23. PMID: 31868064.

Walline JJ, Mutti DO, Zadnik K, Jones LA. Development of phoria in children. Optom Vis Sci. 1998 Aug;75(8):605-10. doi: 10.1097/00006324-199808000-00026. PMID: 9734805.


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