Acute co-morbid internal strabismus is generally classified as non-adjustable internal strabismus because adjustable internal strabismus is internal strabismus caused by refractive error, whereas acute internal strabismus is not caused by refractive error. Strabismus can be categorized into two different types of strabismus, regulatory and nonregulatory, depending on whether or not the cause of the strabismus is related to abnormalities in regulatory function. Patients with accommodative strabismus are usually associated with refractive error, and types of strabismus other than accommodative strabismus are generally categorized as nonadjustable strabismus. The onset of acute common internal strabismus, on the other hand, is not related to refractive error, but is mainly related to neurological abnormalities and fusion function abnormalities, and is therefore categorized as non-adjustable strabismus. Patients with acute internal strabismus are advised to seek prompt medical attention to evaluate their condition and follow medical advice.