Strabismus is defined as a misalignment of the eyes.
Strabismus also called as squint.
Orthophoria – Implies as perfect ocular alignment
without efforts.
Strabismus consists of two subgroups. 1.Hetrotropia – this is a manifest squint.
Esotropia – deviation of eye towards inside.
Exotropia -- deviation of eye towards towards
outside.
Hypertropia-- deviation of eye towards
upside. 2.Hetrophoria—this is a latent ocular
deviation. Eye alignment is maintained with fusional
effort.
Esophoria – inward deviation of eye when fusion is
disrupted.
Exophoria-- outward deviation of eye when fusion is
disrupted.
Hyperphoria-- upward deviation of eye when fusion is
disrupted.
Incyclophoria-- Intortional movement of eye when
fusion is disrupted.
Excyclophoria-- Extortional movement of eye when
fusion is disrupted.
If exotropia is atleast 15 prism
diopter more in up gaze (
25 degree up) than the down gaze
(35 degree) then it called as V
pattern exotropia.(Fig1,2,3)
Causes of V-pattern strabismus
Inferior oblique muscle
overaction
Relative underaction of the
superior oblique muscles
Hypoplasia of the
malar bones
Anti-Mongoloid lid slants
S-shaped contours of the
lower lid
Management
Of V Pattern strabismus
Surgical treatment of
Exotropia with V-pattern
strabismus
with
oblique muscle over action
Lateral rectus muscle
recessions with inferior
oblique muscle weakening
Lateral rectus muscle
recession with Medial rectus
resection with inferior
oblique muscle weakening
Surgical treatment of
Exotropia with V-pattern
strabismus
without
oblique
muscle overaction
Exotropia with V-pattern -
Bilateral lateral rectus
muscle recessions with
up shift
Or
Exotropia with V-pattern -
lateral rectus muscle
recessions with up shift +
medial rectus muscle
resections with down shift
Exotropia with V-pattern -
Bilateral lateral rectus
muscle recessions with
up shift
Lateral rectus muscle
recessions with up shift +
medial rectus muscle
resections with down shift
Surgical
treatment of Esotropia with
V-pattern strabismus with oblique
muscle over action
Medial rectus muscle
recessions with inferior oblique
muscle weakening
Medial rectus muscle
recession with lateral rectus
resection with inferior oblique
muscle weakening
Surgical
treatment of Esotropia with
V-pattern strabismus
without oblique
muscle overaction
Bilateral medial
rectus muscle recessions with
down shift
Medial rectus
muscle recessions with down
shift + lateral rectus muscle
resections with up shift
Bilateral medial
rectus muscle recessions with down shift
Medial
rectus muscle recessions with down
shift + lateral rectus muscle
resections with up shift
Case Report
Exotropia with v pattern due to
secondary inferior oblique over
action grade 4
This patient had left eye secondary
inferior oblique over action (IOOA)
due to left superior oblique under
action. He also had exotropia in
primary position which increases
remarkably in up gaze. This patient
also head abnormal head turn to the
right side (Image 1 and 2)
Image 1: Pre
operative nine gazes showing
Exotropia with v pattern due to
secondary inferior oblique over
action
Image 2: The
three-step test, also known as the
Parks-Bielschowsky three-step test
or the Parks-Helveston three-step
test
(Photos
Courtesy : Dr Sudhir Singh,MS)
Post operative
day 1 after left lateral rectus
recession 8 mm and inferior oblique
10 mm myectomy
