From the Guidelines
Eye deviation, also known as strabismus, is primarily caused by problems with the eye muscles or the nerves that control them, as well as various other factors including genetic predisposition, neurological disorders, trauma, or certain medical conditions, as noted in the most recent study on adult strabismus preferred practice pattern 1. The condition can result from several factors, including cranial nerve palsies (particularly affecting the 3rd, 4th, or 6th cranial nerves), muscle abnormalities, uncorrected refractive errors (like farsightedness), childhood illnesses, stroke, brain tumors, or head injuries. Some key points to consider in the diagnosis and treatment of strabismus include:
- The examination should include a full sensorimotor examination, noting evidence of mechanical restriction, as outlined in the adult strabismus preferred practice pattern 1.
- Treatment options vary based on the cause and may include corrective eyeglasses, prism lenses, vision therapy exercises, eye muscle surgery, or Botox injections into specific eye muscles.
- Early diagnosis and treatment are crucial, especially in children, to prevent permanent vision problems, as the brain needs to receive proper visual input from both eyes during critical developmental periods to establish normal binocular vision.
- The goals of treatment should be broader and include sensory recovery when possible, as well as gains in psychosocial and functional domains of vision-related quality of life, with success rates depending on the subpopulation studied and the goals of surgery, approximately 80% after one procedure and may exceed 95% if a second procedure is performed on eyes failing the first intervention 1.
From the Research
Causes of Eye Deviation (Strabismus)
- Strabismus is not a condition in itself, but rather the consequence of an underlying problem, which can be caused by disease, injury, and/or abnormalities in any of the structures and processes involved in visual perception and oculomotor control 2
- The possible causes of strabismus can be categorized into two main types: peripheral and central, with peripheral strabismus resulting from well-described genetic syndromes, acquired insult, or disease affecting the extraocular muscles (EOMs) or their innervations, and central strabismus resulting from deficits in the central neural pathways involved in visual perception and oculomotor control 2, 3
- Central strabismus is believed to be caused by abnormalities in the sensory and/or motor systems, both peripherally and/or in the brain itself, and can result from a wide variety of factors, including genetic and/or acquired factors, anatomical and/or functional abnormalities 3
- The exact cause of strabismus is not fully understood, but it is recommended that all children have their vision checked by their pediatrician, family doctor, or ophthalmologist at or before their fourth birthday to detect any potential issues early on 4
- In some cases, strabismus can be caused by lesions of the central nervous system, and treatment may involve surgery, eye drops, eye glasses, exercises, and injections, depending on the type of strabismus present 4, 5
- Research has also identified several genes that are necessary for the normal development and connectivity of brainstem ocular motoneurons, and mutations in these genes can result in complex strabismus syndromes, such as the congenital cranial dysinnervation disorders (CCDD) 6
Types of Strabismus
- Comitant strabismus: a type of strabismus where the angle of deviation remains the same in all directions of gaze 2
- Non-comitant strabismus: a type of strabismus where the angle of deviation varies in different directions of gaze 2
- Cyclic strabismus: a rare disorder in which strabismus and orthotropia regularly alternate over a period of time, often 48 hours 5