Determination of the Correlation Between Types of Strabismus and Certain Medical Conditions

Abstract

There are numerous subtypes of strabismus: esotropia where one eye deviates inward compared to the other, exotropia where one eye deviates outward compared to the other, hypertropia where one eyes is higher than the other, concomitant strabismus where the degree of deviation is the same in each gaze, incomitant strabismus where the degree of deviation varies in different gazes. Adult strabismus can be caused by various conditions including vasculopathic diseases (diabetes, hypertension, and stroke), compressive CNS lesions, myasthenia gravis, sensory strabismus, thyroid ophthalmopathy, multiple sclerosis, trauma, post-surgical strabismus, recurrent childhood strabismus, longstanding adult strabismus without proven cause, syndrome related strabismus, restrictive orbital masses, and congenital fibrosis of the extraocular muscles. It is currently unknown whether any of these underlying conditions correlate with a specific type of strabismus. The purpose of this study is to determine if underlying conditions correlate with a certain misalignment (i.e. esotropia, exotropia, hypertropia, concomitant, or incomitant). If there is a statistically significant correlation between a certain misalignment and systemic disease, this could add to the algorithm that physicians use to diagnose these systemic conditions. This was a retrospective review of 692 patients >=21 years of age who presented to a pediatric ophthalmologist with adult strabismus from September 2008 to September 2015. The inclusion criteria were: (1) an age of 21 years or older, (2) a confirmed diagnosis of new-onset or recurrent childhood strabismus, (3) any severity and type of deviation, and (4) documentation of diplopia in any field of gaze. The variables that were extracted from the files were: the type of misalignment (esotropia, exotropia, hypertropia, concomitant, incomitant) and the underlying disorder (vasculopathic diseases (diabetes, hypertension, and stroke), compressive central nervous system (CNS) lesions, myasthenia gravis, sensory strabismus, thyroid ophthalmopathy, multiple sclerosis, trauma, post-surgical strabismus, recurrent childhood strabismus, longstanding adult strabismus without proven cause, syndrome related strabismus, restrictive orbital mass caused strabismus, and congenital fibrosis). Interpretation of the data consisted of determining if a correlation between type of misalignment and underlying condition exists. The average age of the population is 60.5 years with a standard deviation of 16.9, of which 49.6% were male. Results of this study indicate that multiple conditions that cause strabismus have a proclivity to negatively or positively predict a certain type of strabismus. Specifically, post-surgical patients are more likely to have hypertropia than esotropia or exotropia, sensory strabismus patients are more likely to have exotropia. Adult patients with recurrent childhood strabismus are more likely to have exotropia and concomitancy. Compressive CNS lesions, thyroid ophthalmopathy, and traumatic causes of strabismus are more likely to cause incomitant strabismus. Vasculopathic causes of strabismus do not have a tendency to cause any certain type of strabismus. These findings will assist ophthalmologists in delineating a cause of their patient’s strabismus based on which types of strabismus correlate with certain conditions.