Simultaneous prism CT
Estimated prism over deviated eye
Occluder over fixating eye
EF vs ARC
EF:
- monocular
- amblyopic eye using non-foveal pt
- degrees or PDs
ARC:
- binocular
- fovea of fixating eye has same visual direction as non-foveal pt of non-fixating eye
- PDs
4 types of retinal correspondence
Normal/NRC: H = S, A = 0
Anomalous/ARC: H ≠ S, A ≠ 0
Harmonious/HARC: H = A, S ≠ 0
Unharmonious/UHARC: H > A, H > S
EF vs ARC evaluations
EF: visuoscopy, HB, AI
ARC: W4D, Bagolini, Red Lens, Synoptophore, HB, AI
-looking for embeddedness (most natural/mild -> most artificial/deep)
Mild vs deeply embedded ARC
Mild:
- 80%
- moderate/large/variable angles
- seen with Bagonlini only
- no tx
Deep:
- small, stable angle
- early onset
- rarely eliminated
- present on 3-4 tests
Goals of tx (Flom’s criteria) - Functional cure
- Clear, single BV
- Stereo & normal vergences
- Deviation 1% of the time, must have diplopia w/
- May have prism (~5pd) to assist fusion
Goals of tx (Flom’s criteria) - Almost cure
- clear single BV
- some stereo
- deviation 5%, must have diplopia w/
- may have large amnt of prism to assist with fusion
Goals of tx (Flom’s criteria) - Moderate improvement
- improvement in any 2 “above”
- amblyopia is present
- EF
Goals of tx (Flom’s criteria) - Some improvement
-improvement in only 1 thing
Goals of tx (Flom’s criteria) - No improvement
Microtropia
Prognosis for ARC better
- exotropia
- intermittent
- large angle
- older children
- mildly embedded
- Flom’s functional or almost cure
Prognosis for ARC worse
- esotropia
- constant
- small angle
- younger children
- deeply embedded
*contraindication for ARC therapy
Horror fusionis
When do we use prism for strabismus
pts with NRC or to break ARC
4 techniques to reestablish NRC with cosmesis for ARC pts
Prism & disruptive techniques
Occlusion therapy
Vision therapy
Surgery
ARC tx: prism & disruptive techniques - purpose
Create instability of the angle
- not sure of efficacy
- poor compliance, discomfort/diplopia, time consuming
- difficult to do all day due to constant diplopia & cosmesis
ARC tx: prism & disruptive techniques - overcorrection
Works well w/ younger children to disrupt ARC by stimulating latent NRC localization
ARC tx: prism & disruptive techniques - phases
1) overcorrect by ~15pd all day
2) after few months & when NRC is repeatedly seen on AT, needed power will be = to objective angle
- start VT
- prism can be gradually reduced
- if angle is still large, consider sx
ARC tx: occlusion
Development of ARC prevented if occlude early enough
Occlude for amblyopia first
Total occlusion for 24 hrs, alternating days
Poor compliance
ARC tx: occlusion - purpose
Disrupt ARC localization & prevent reinforcement
Break suppression
Tx amblyopia
ARC tx: constant total occlusion
Children w/ constant strab that started before age 7
Be cautious in cases of intermittent strab - occlusion strab can result
ARC tx: binasal occlusion
*Can be used in children with ET to prevent/tx any ARC
Beware with children that are active, have large head movements for fixation (“cheating” around the occlusion)
*Fixating/good eye has wider occlusion than bad eye
ARC tx: VT
Anti-suppression, amblyoscopes, & stereoscopes can be used
Forces strabismic eye to fixate
Works on motor ranges as well
ARC tx: surgery
May report NRC after sx, esp. those with mildly embedded ARC
Possible results: NRC, ARC, covariance, paradoxical UHARC
