ophthalmology strabismus/pediatrics

MR= 5.5 mm, IR=6.5mm, LR=6.9mm, SR=7.7mm

Intermittent convergence, accommodation, miosis; often mistaken for bilateral 6th N palsies; may be non-physiologic; MRI==r/o lesion, MS, wernickes, chiari, 1) new myope, 2) miosis on lateral gaze

congenital or acquired fibrosis of SO tendon; girls>boys, OD 55%, OS35%, OU 10%; can present w/ ET; cannot elevate adducted eye; CAN elevate abducted eye; confirm dx w/ forced duction; acquired may spontaneously improve

maternal cigarette smoking, low birth weight

>30PD, onset <6mo, cross fixation—therefore no amblyopia, latent nystagmus, DVD (60-70%), IOO (60-70% V pattern), mild hyperopia—can have accommodative component
Risk factors: maternal cigarette smoking, low birth weight, increasing maternal age, white race

2-4pd independent of fixation distance

up to 6pd distance/16pd near

up to 14pd distance/38pd near

usually intermittent then becomes constant; ambyopia is very common (>95%)—unless child alternates fixation; diplopia is rare; 20%=high AC/A & need bifocals; surgery leaving <10PD residual ET allow for development of peripheral fusion

facial paralysis; dense ET; underdevelopment of CN6 & 7 (&occ 5&8);

exception to Sherringtons Law as LR is innervated (aberrant nnervations) in part by MR division of 3rd N. due to CN6 agenesis

exception to Herings law; during visual inattention, 1 eye drift up, out & extorts w/out any innervations to contralateral eye; bilateral & symmetric (looks like a hyperphoria, but second eye does not shift when cover removed); variable measurements; +correlation with cong esotropia; can be bilateral

abn horizontal gaze, retraction of globe & upshooting or downshooting of globe; OS>OD, girls>boys; associations: cataract, iris anomalies, marcus gunn jaw winking, microphthalmos, crocodile tears, goldenhars, maternal thalidomide, klippel-feil syndrome (cervical spine fusion), hearing loss; amblyopia=10%
--differentiate from 6th N palsy w/ forced ductions---if longstanding 6th, MR undergoes contracture

from exotropia, post op goal=8-15 ET; if >20PD, re-op; if<4y/o & diplopic, consider alternate patching to prevent suppression

(simulated divergence excess) XT > XT’, if after 30 min patching XT=XT’

XT > XT’; after 30 min patch, XT>XT’ (by at least 10PD), then measure w/ +3.00D to determine AC/A ratio; if XT=XT’ w/ +3.00high AC/A & these pts are prone to overcorrection; therefore, undercorrect slightly for distance & warn parents of likely need for bifocals to correct AC/A post op

Orthoptics

when 1 EOM is stimulated, contralateral eye yolk muscle receives equal innervations; except DVD

when 1 EOM is stimulated, the ipsilateral antagonist is inhibited; except Duanes

ESO: Medial recess=6mm; lateral resect=9mm
EXO: Medial resect=10mm; lateral recess=10mm

MALE: move medial rectus towards apex of A or V by ½ muscle width +/- R&R OR do myectomy of inf oblique—(which causes esodeviation in upgaze by 15-25PD) (if myectomy is done, just do R&R, no need for MALE) (superior oblique tenotomy, causes esoshift up to 40PD
A eso: if >35—do R&R + superior oblique tenotomy, <35 do R&R + MALE