Pattern Strabismus
How many prism diopters difference are required to classify as V pattern?:
15
How do you name a vertical deviation?
According to the hypertropic eye. Although hypotropia can be used for a patient who has a strong fixation preference for the hypertropic eye
List the muscles involved in restrictive processes in Thyroid Eye Disease from most common to least?
Inferior rectus, medial rectus, superior rectus, lateral rectus, obliques
Approximately ___ of correction in primary position can be expected for every millimeter of vertical rectus muscle recession
3Δ
What are the two most common types of patterns strabismus and the three less common types?
•Most common: A and V.
•Less common: Y, X, and lambda.
What test is used to help diagnose superior oblique (SO) palsy?
Park-Bielschowsky 3-step test. Can also use double Maddox rod
What is the defining clinical feature of Duane Retraction Syndrome that differentiates it from sixth nerve palsy?
The defining clinical feature that differentiates Duane Retraction Syndrome from sixth nerve palsy is globe retraction on adduction, which causes narrowing of the palpebral fissure
What are the signs of ASI and how is it treated?
cells and flare – then k edema; treat with steroids
How do you treat pattern strabismus with oblique overaction?
Weaken the oblique! IO Myectomy
List 2 ways to tell if a SO palsy is congenital (not acquired):
1. look at old photos
2. large vertical fusional amplitude (the eyes can overcome a big vertical difference (prism) to keep vision single)
List 3 causes of non-congenital Brown syndrome?
Trauma in the region of the trochlea, scleral buckles, orbital tumors, tube shunts, inflammatory conditions (RA)
What is PITS syndrome and name 2 risk factors.
advanced age, myopathies, previous surgery, trauma or infiltrative disease
How do you treat pattern strabismus without oblique overaction?
Vertical Transposition; Medial rectus to Apex, Lateral rectus to Empty space (MALE)
Describe “Spread of comitance” in SO palsy, and specifically which muscle(s) involved.
Starts as incomitant, but overtime, ipsilateral SR and contralateral IR contract, causing there to be minimal difference in the magnitude of hypertropia when the patient looks from one side to the other
What do you see on exam in internuclear ophthalmoplegia?
On horizontal versions, the eye ipsilateral to the MLF lesion adducts slowly and incompletely or not at all, whereas the abducting eye exhibits a characteristic horizontal jerk nystagmus. Both eyes adduct normally on convergence
Which muscle is most problematic when it is ‘lost’ during surgery and why?
medial rectus – it has no other attachments
How do you surgically treat V pattern with a DVD?
Anterior transposition of IO
What is the hallmark finding of skew deviation?
Vertical strabismus that mimics SO and IO palsy, but the torsion is opposite of what you would expect. Also, if you lay them supine, the vertical tropia improves.
This condition differs from a simple nerve palsy, as it involves central processing disruption, not just a single nerve, and often presents with other neurological signs like dizziness, nystagmus, and ataxia
What are the three characteristic features that form the triad of Kearns-Sayre syndrome?
The triad of Kearns-Sayre syndrome is characterized by retinal pigmentary changes, chronic progressive external ophthalmoplegia (CPEO), and cardiomyopathy (heart block)
What procedure is used for 6th nerve palsy with no abduction past midline?
transposition of vertical rectus muscles