Strabismus
Ophthalmology
Strabismus
Comitant
non-comitant
Monocular elevation deficiency
Möbius Syndrome
Brown syndrome
Duane syndrome (a cause of congenital strabismus)
Parinaud's Syndrome (overlap with sylvian aqueduct syndrome)
Strabismus
- Orthophoria = ocular balance in all directions and depths
- Heterotropia aka Manifest (present on binocular gaze) v Heterophoria aka Latent (only on occlusion)
- i.e. heterophoria can be overcome by fusion heterotropia cannot
- Unilateral v Alternating (better as both eyes develop)
- Comitant (degree is constant) v non-comitant (degree changes with direction)
- Eso- aka convergent aka cross-eyed
- Exo- aka divergent aka wall-eyed
- Hyper, hypo, and torsional
- Most people have a very small latent heterophoria which is compensated by binocular fusion
- Symptoms: headache, asthenopia (eye strain)
- Look for compensatory head position
- 1/3 get amblyopia aka vision loss (others causes: cataract, anisometropia)
- Pseudostrabismus = apparent strabismus in infant due to relative prominence of epicanthus and less sclera visible
- Hirschberg corneal reflex test = shine light on both eyes, light should reflex just nasally to pupils
- Cover-uncover and alternate-cover test: look at 6m chart / shaking toy, movement with test = phobia
Comitant
- Esotropia =50%
- Cross-fixation is looking to left with right eye and right with left eye
- After correction relapses are common (inc 1 and 2) regular follow-up
- dissociative vertical deviation (one eye drift up when focusing)
- inferior oblique overaction (up gaze of left eye when looking right AND vice versa see below)
- Accommodative esotropia: one eye is hyperopic, brain tries to correct by accommodating more, but accommodation is linked to convergence, so eye also converges. Rx with corrective lens (once treated the esodeviation without glasses increases now the eye is functioning properly)
non-comitant
- ?trauma, ?neuro ?systemic
- CNIII palsy (exo+hypo+ptosis): controls all but lateral rectus and superior oblique. congenital, birth trauma, intracranial neoplasm, aneurysm, inflammatory, infection, trauma, postviral syndromes, migraines.
- CNIV palsy (sup obliq): hypertropia on nasal gaze. Head tilt to opposite shoulder with head down. Rx surgery
- CNVI palsy (lat rec): head turn to affected side, not down. Neonate can have transient palsy which resolves by 6 weeks. Acquired ?ICP > hydrocephalus or tumour. All of CNIII's DDx. Gradenigo's syndrome: Otitis media inflaming CNV (periorbital pain) and VI (diplopia)
Monocular elevation deficiency
- hypotropia and pseudoptosis (double paralysis of sup rec and inf obliq)
Möbius Syndrome
- facial palsy and esotropia
- Associated developmental defects include ptosis, palatal and lingual palsy, hearing loss, pectoral and lingual muscle defects, micrognathia, syndactyly, supernumerary digits, and the absence of hands, feet, fingers, or toes
Brown syndrome
- downward deviation in adduction
- superior oblique is tight restricting movement
- ?sinusitis ?JRA
Duane syndrome (a cause of congenital strabismus)
- retraction on adduction
- congenital absence of CNVI nucleus > aberrant innovation > co-contraction of med/lateral rectus
- sporadic or AD
Parinaud's Syndrome (overlap with sylvian aqueduct syndrome)
- up gaze paralysis with convergence nystagmus, loss of light reflex but accom reflex preserved
- ?pineal or 3rd vent tumour
- Sunsetting: paralysis of up gaze with lid retraction > hydrocephalus