Optometry & Visual Performance 290 Volume 13 | Issue 4 | December 2025 Young Children (1-6 years) Amblyopia (20/40-20/200 VA), variable postures, motor delays; early intervention prevents irreversible loss. Deviations may be constant or intermittent, with compensatory postures more pronounced. Age-related patterns show congenital strabismus asymptomatic due to suppression. Motor delays, clumsiness, drawing difficulties Glasses, MFBF therapy, patching, surgery; prevent amblyopia; assess school readiness. School-Age/Adolescents (7-18 years) Reading fatigue, intermittent diplopia, academic challenges; refractive factors dominant. Functional impacts like asthenopia during school tasks or near-work avoidance. Academic decline, social withdrawal Vision therapy, prism, ergonomic adjustments, visual hygiene. Adults (>18 years) Sudden diplopia, vertigo, cranial palsies; psychosocial distress common. Acquired cases correlate with trauma or systemic/neurologic diseases. Occupational impacts, driving risk, reduced QoL Urgent neuroimaging; vision therapy with prism or surgical considerations. Pathophysiology The pathophysiology of strabismus is multifactorial, involving disruptions in the coordinated control of the six extraocular muscles and their neural pathways. • Innervational Deficits: • Cranial Nerve Imbalance: Imbalances in cranial nerve supply (i.e., CN VI palsy causes unopposed medial rectus action, leading to esotropia). Anomalous innervation (i.e., co-contraction in Duane syndrome). Supranuclear lesions like progressive supranuclear palsy disrupt Sherrington's law (muscle of one eye and the antagonist of the same eye) and Hering's law (yoke/synergist muscles of both eyes). • Cyclovertical Palsies: Predominant in superior oblique paralysis linked to fourth cranial nerve dysfunction. Congenital forms feature large vertical fusion ranges; acquired cases (trauma, microvascular events) cause acute onset diagonal diplopia without large vertical fusion ranges. • Mechanical / Restrictive Factors: • Muscle Fibrosis/Tendon Restrictions: Physical limitations from muscle fibrosis or tendon restrictions (i.e., Brown syndrome with tight superior oblique tendon). Forced duction testing reveals resistance. • Orbital Floor Fractures: Entrapment with positive forced duction, hypoesthesia, and enophthalmos. Mechanical restriction from trauma, affecting motility and alignment. • • Refractive / Sensory Components: • Uncorrected Hyperopia: Hyperopia (>+3.00D) can trigger excessive accommodation, activating convergence via AC/A ratio (>6:1 in accommodative esotropia). Leads to inward deviation due to refractive/accommodation/ convergence synkinesis. • Sensory Strabismus: Arises from unilateral visual loss (cataract, retinopathy), deviating the poorseeing eye. The brain adapts by deviating the weaker eye to avoid confusion, leading to suppression or ARC. • Central / Neurogenic Elements: • CNS Microstructural Changes: Developmental or acquired CNS disruption affecting eye movement control (decreased cerebellar vermis, superior colliculus connectivity). • Genetic Mutations: Mutations like ROBO3 in Duane syndrome or PHOX2A in congenital fibrosis of extraocular muscles provide a genetic basis for anomalous innervation or muscle development issues. • Developmental Failures: Failures in primitive reflex integration or proper visual experiences (visual stress, limited tummy time, uncorrected refractive error, lack of free play, etc.), leading to maladaptations. Early visual system maturation issues contribute to strabismus persistence. • Proprioceptive Disruption: Loss of feedback control in extraocular circuitry during early development. Leads to binocular vision loss due to impaired sensory-motor integration.
RkJQdWJsaXNoZXIy MjEyMDQ0Nw==