A & V patterns 3 Flashcards
RAD SIN
Vertical Rectus muscle ADduct
Superior muscles INtort
5∆BO on elevation, 15∆BO in PP, 35∆BO in depression
V ESO
Greatest deviation is in depression, more convergent looking down than looking up
5∆BI on elevation, 18∆BI in PP, 25∆BI on depression
A EXO
More divergent looking down so A exo, more convergent in elevation
V pattern can be caused by IO over action and SR underaction
IO= an abductor so an overaction- more divergence looking up.
SR= an adductor so an underaction- less adduction and more abduction and SO underactor- less abduction looking down (-= abductors, +=adductors)
A pattern possible cause-which u/a and o/a muscles
SR overaction and IR underaction. A pattern has more abduction in elevation, overaction of SO (abductor) more divergence and IR underaction with IO underactor
V ESO more convergent where and which muscles overacting
overaction of MR and is more convergent looking down
What does MR insertion too high cause
causes V pattern. Insertion is too high, so the muscle in elevation becomes more slack so less adduction, MR is an adductor, less elevation in adduction
LR insertion too low
causes V pattern as LR is abductor and there is more slack on downgaze, less abduction, more adduction in LR depression
Oblique muscle positioned too anterior leads to which alphabet pattern
The abducting force of SO is weakened an lead to a V eso
Saggitalisation of SO
The angle between the SO and visual angle is reduced compared to angle for IO, and leads to SO and SR contract to compensate for the torsion and causes SO over-action and A pattern
Saggitalisation
It is muscle is closer to the anterior/posterior axis of the globe
- look at the inferior oblique and So to see which muscles are contracting to compensate
Saggitalisation of SO
- Superior muscles are contracting so overacting SO and SR overactions- which gives an A pattern
Saggitalisation of IO
Inferior muscles (IO and IR) are contracting so overactions of this causes a V pattern
Surgery for V pattern
Anterior transposition of IO
IO position more anterior- weakening so anterior transposition will weaken and less abduction so close V
Surgery for A pattern
SO tenotomy
SO Overacting in A- tenotomy weakens the SO- Transpose LR upwards will cause less divergence on elevation and increase the a pattern and increased abduction on depression
Surgery of V eso
Bilateral MR recessions and IO myectomy
Correct eso deviation- weaken medial recti then IO is overacting in A pattern so IO is weakened in a myectomy
Surgery for A exo
LR recess/MR resect and SO tendon spacer
SO tendon spacer- spacer between tendon so making it longer and weakening the SO to close the A
Case 1- History
24 year old patient presents with asthenopic symptoms
Bilateral LR recession (5mm) for XT aged 15 years
Bilateral MR resection (5mm) inferior displacement of each MR for XT with associated A pattern aged 20 years
Present prescription
R -8.00/+2.25x96
L -7.00/+1.75x94
VA R 0.1 L 0.1
CT cgls N sl/mod intermittent XT c brief control
cgls sl D intermittent XT
OM A exo more abduction in down gaze
Worth lights cgls N&D BSV
Titmus test cgls 100 sec of arc
PCT N and D 18∆BI
Aetiology- MR was moved down, MR more slack looking down so more abduction looking down A pattern is worse and SO OA makes it larger
2BO elevation
10BI PP
40BI depression
A exo
Management- LR recess and MR resection with SO tenotomy
5 year old boy. Parents noticed esotropia from approximately 1 year of age
Angle of deviation has increased and noticed all the time now, parents are keen for treatment
No refractive error
VA R 0.3 L 0.0 Crowded logMAR
CT N & D mod RET
Bagolini gls N & D Right suppression response
Synoptophore Objective: +15 degrees Subjective: right suppression (peripheral slides)
PCT N + D 30 BO
Aetiology- IO overaction and SR underaction
Expected anomaly- IO overaction and SR underaction
20 BO elevation
30 BO PP
40 BO depression
V eso
Management- MR recession and IO myectomy/myotomy or IO recession or Anterior transposition
30 year old female is unhappy with appearance of strabismus and keen for surgery.
5’2 tall, prev surgery for convergent strabismus and patching treatment as a child.
Refractive error:
R -0.50/+0.25*80 L -2.50DS
VA cgls R 0.16 L -0.04 l
CT c and sgls
N sl/mod RXT
D mod RXT
OM- V exo
V ESO
Expected anomaly IO overaction and SO underaction
Surgical options
Bilateral LR recession and IO myotomy/myectomy or recession work on the IO muscle for the V Pattern
Bilateral IO weakening
Alphabet patterns
Tend to operate on both muscles
TO KNOW
Define patterns
Know aetiological factors
Diagnosing patterns
Surgical management options
