Adult strabismus refers to a condition where the eyes do not properly align with each other, meaning they point in different directions. This misalignment can be constant or intermittent, affecting how both eyes work together to focus on a single object. It impacts an individual’s vision and daily life.
Understanding Adult Strabismus
Adult strabismus differs from childhood strabismus primarily in its onset and the brain’s response. While childhood strabismus often develops early in life, adult strabismus can appear later, either as a recurrence of a previously treated childhood condition or as a new development. In children, the brain typically adapts to avoid double vision by suppressing the image from the misaligned eye, potentially leading to amblyopia. An adult brain cannot usually suppress images, so adults with new-onset strabismus frequently experience double vision.
The misalignment can manifest in several ways. Esotropia describes an inward turning of one or both eyes, while exotropia involves an outward turn. Hypertropia means one eye turns upward, and hypotropia indicates one eye turns downward. These misalignments prevent the eyes from sending a unified image to the brain, disrupting the ability to create a single, three-dimensional picture. This affects depth perception and overall visual function.
Factors Contributing to Adult Strabismus
Adult strabismus can arise from various underlying causes that affect the eye muscles, the nerves controlling them, or the brain’s ability to coordinate eye movements. Neurological conditions, such as strokes, multiple sclerosis, or myasthenia gravis, can impair the nerves responsible for eye movement.
Thyroid eye disease, also known as Graves’ ophthalmopathy, is another common factor where inflammation and fibrosis of the extraocular muscles restrict eye movement, leading to misalignment. Trauma, including head injuries or direct injury to the eye, can damage eye muscles or their controlling nerves. Previous eye surgeries, such as cataract surgery or retinal detachment repair, can sometimes lead to muscle damage and misalignment. Systemic diseases like diabetes can also contribute by affecting circulation to the nerves or muscles involved in eye movement.
Identifying the Signs
Recognizing adult strabismus often involves observing both visual disturbances and physical signs. A primary visual symptom is double vision, where a single object appears as two separate images. This occurs because misaligned eyes send different images to the brain, which struggles to fuse them.
Other visual symptoms include eye strain and fatigue, especially after prolonged visual tasks like reading or computer use. Individuals may also experience blurred vision, difficulty focusing, or reduced depth perception. Physical signs can include a noticeable eye turn. Some individuals may also adopt an abnormal head posture, such as tilting or turning their head, to achieve clearer single vision.
Diagnosis and Management Options
Diagnosing adult strabismus begins with a comprehensive eye examination performed by an ophthalmologist or optometrist. This evaluation includes visual acuity tests to assess vision and refraction tests to check for focusing errors. Specific tests like the cover test and prism and alternate cover test help detect and measure eye misalignment. These tests allow the specialist to identify how well the eyes move and determine the type of strabismus.
Management options are often individualized. Non-surgical approaches include prescription glasses to correct refractive errors, which can sometimes help align the eyes. Prism lenses are another option; these special lenses bend light, shifting the image to compensate for the misalignment and reduce double vision. While prisms do not correct alignment, they can trick the brain into perceiving a single image.
Vision therapy, involving eye exercises, can help improve eye coordination in some cases. Surgical correction is a common and effective treatment, aiming to realign the eyes by adjusting eye muscle length or position. This procedure can improve double vision, depth perception, and the visual field, and is frequently performed in an outpatient setting.