Sensory exotropia is a type of strabismus, a condition where the eyes do not align properly. Here, one eye consistently turns outward while the other remains focused. This eye misalignment can affect individuals at any age, distinguishing it from other types of exotropia that appear at birth or during early development. Understanding this condition involves recognizing how impaired vision in one eye drives the outward deviation.
What is Sensory Exotropia?
Sensory exotropia develops when one eye experiences reduced vision. Unlike other forms of exotropia that may stem from muscle imbalances, this condition originates from a significant difference in visual input between the two eyes. The term “sensory” highlights that the misalignment is a consequence of the brain’s inability to fuse disparate images. When one eye provides a blurry or incomplete picture, the brain often suppresses that image to avoid confusion or double vision, leading the poorly seeing eye to drift outward.
Primary Causes
Reduced vision in one eye, which underlies sensory exotropia, can stem from various ocular conditions. Amblyopia, commonly known as “lazy eye,” is a frequent cause where the brain favors one eye due to abnormal visual development, leading to diminished vision in the unfavored eye. Other contributing factors include physical obstructions like cataracts, which cloud the eye’s lens and impair light transmission. Damage to the optic nerve or various retinal diseases can also significantly reduce visual acuity in one eye, disrupting the brain’s ability to combine images from both eyes. A substantial difference in refractive error between the two eyes, known as anisometropia, can also lead to this condition as the brain suppresses the image from the eye with the greater error.
Recognizing the Signs and Diagnosis
Observing an outward turn of one eye is the primary indicator of sensory exotropia. This deviation may initially be intermittent, becoming more noticeable when a person is tired, unwell, or focusing on distant objects. Individuals might also experience reduced depth perception, difficulty judging distances, or report headaches and eye strain from attempting to align their vision. Children with the condition may squint or close one eye, particularly in bright light, to compensate for the misalignment and avoid visual confusion.
Diagnosis requires a comprehensive eye examination performed by an eye care professional. This evaluation includes visual acuity testing to assess how well each eye sees. A refraction test helps determine the presence and degree of any refractive errors. The eye doctor will also perform an ocular motility assessment to observe eye movements and alignment. Examination of the internal structures of the eye, such as the retina and optic nerve, is also conducted to identify the underlying cause of vision loss.
Treatment and Management
Addressing sensory exotropia involves a two-pronged approach: treating the underlying cause of vision impairment and then working to align the eyes. If conditions like cataracts are present, surgical removal may be performed to restore vision in the affected eye. For amblyopia, treatment often involves patching the stronger eye or using atropine eye drops in the stronger eye to encourage the weaker eye to develop better vision.
Following or alongside vision improvement, various methods can help achieve eye alignment. Corrective lenses, such as glasses or contact lenses, can address significant refractive errors. Prism glasses might be prescribed to help fuse images and reduce double vision. When non-surgical methods are insufficient, eye muscle surgery may be recommended to physically reposition the muscles controlling eye movement, aiming to straighten the eye and improve its appearance. The goal of treatment is to enhance visual function and achieve satisfactory eye alignment.