EF And ARC Therapy Flashcards
Simultaneous prism cover test (SPCT)
A variation of CT to measure deviation
- estimates the deviation
- the amount of estimated prism is placed over the deviated eye as the occluder is placed over the fixating eye
- repeat, increasing the prism until no shift is seen as the prism and the occluder are introduced
- prism goes over the deviated eye
Eccentric fixation
- monocular sensory adaptation
- amblyopic eye using a non fovea point
- localization, size, steadiness
- in degrees or prism diopters
ARC
- binocular sensory adaptation
- fovea of fixating eye and non fovea of non fixating eye have common visual direction (under binocualr conditions)
- objective angle, subjective angle, angle of anomaly
- in prism diopters
Is EF the same as ARC?
No
Normal correspondence
Objective angle equals the subjective angle and the angle of anomaly is 0
Anamalous correspondence
Objective angle does not equal the subjective angle and the angle of an anomaly does not equal 0
Harmonious ARC
Objective angle equals the angle of anomaly, the subjective angle equals 0
Unharmonious ARC
Objective angles is greater than the angle of anomaly, objective angle is greater than the subjective angle
Which actually gets us some type of binocualr vision
ARC
-EF does not
EF is evaluated with
Visuoscopy
Haidinger brushes
After image transfer
ARC is evaluated with
W4D Bagolini lenses Red lenses Amblyopscope/synoptophore After image transfer (angle of anomaly) Haidinger brushes (angle of anomaly)
Classification of EF
- central or eccentric
- steady or unsteady
- location (nasal, temporal, superior, inferior)
- magnitude
Embeddness of ARC
Most natural (mildly) to the most artifical (deeply embedded: smaller angles)
- bagolini
- vertical prism to alignment (red lens)
- W4D
- after image test
Mildly embedded ARC
- about 80% of cases
- comprises of moderate angles, large angles or variable angles
- present only on bagolini
- no treatment for ARC is required
- strab can be treated with prisms, VT and/or surgery
Deeply embedded ARC
- smaller angle
- more stable angle
- early onset
- rarely possible to eliminate ARC
- Present on 3-4 test
Moderately embedded ARC seen on ___- ARC tests
2
Goals of treatment: criteria for cure
Cosmesis
Floms criteria
- functional cure
- almost cure
- moderate improve
- some improvement
- no improvement
Goal of treatment: cosmesis
This is to decrease the sizeto make it less noticeable
Functional cure
- clear single BV at all D and gazes
- stereopsis and normal vergence ranges
- deviation can occur (1% of the time), but when it occurs diplopia must occur
- may have prism (~5Pd) in the glasses to assist with fusion
Almost cure
- clear single BV
- some stereopsis
- deviation can occur (5% of the time), but diplopia must occur
- may have large amount of prism to assist with fusion
Moderate improvement
- improvement in any of the 2 above
- amblyopia is present
- eccentric fixation
Some improvement
Improvement of only one thing
No improvement
Found in micro tropia
Better prognosis ARC
- exotropia (better if they have NRC vs ARC)
- intermittent (XT or ET)
- larger angles
- older children
- mildly imbedded (seen on bagolini)
Worse prognosis ARC
- esotropia (better if the patietn has NRC vs ARC)
- constant
- smaller angles (ARC is easily developed), smaller angles of anomaly
- younger shildren (<3)
- deeply imbedded
Floms functional or almost cure is more likely for
All of the “better” prognosis ARC pateitns
Why is it sometimes recommended not treating ARC
It gives them some BV
Ttreatment for ARC
- decision to treat is based on the embeddness
- depending on the embeddness, you wither want to: eliminate ARC to reestablish nornal BV (NRC) with cosmesis or further embed ARC
Mana gent plan of strab
- determin the Dx
- create plan
- commiunuaite concditin and management plan to patietns
- discuss pros and cons of the different treatment options, if applicable
Treating ARC requires
Time, money, dedication
Results in many cases of ARC treatment
Eye strain, diplopia (sometimes intractable)
If you want to treat ARC, best things to do
- refer to s a BV specialist
- difficult to recommend therapy if a cure can not be achieved in a year. If it is a referral, you could do a trial of a couple of sessions to determine if there is a chance for improvement
Treating ARC in post surgical cases
If they result in HARC (which is some form of peripheral BV). VT can be recommended if ARC is mildly embedded
What is contraindicated for ARC therapy
Horror fusionis
-they will never fuse
Management plan for ARC
- optical management
- added lenses
- prism (ONLY EVER FOR NRC)
- occlusion
- VT
- pharmacological managemtn
- surgical management
Prism and ARC
Only used to improve the angle in patietns with NRC
In ARC-prism to break ARC
Goal of treatment of ARC: eliminate ARC to reestablish normal BV
- prism and disruptive techniques
- occlusion
- VT
- surgery
Prism and disruptive techniques for ARC
Lenses and prisms
- with correcting, overcorrecting, reverse or vertical prisms
- crease instability of the angle
- not sure of the efficacy
- poor compliance, discomfort/diplopia
- difficult to do this all day ebvcsue of sontant diplopia
By overcorrecting, the patietn now has to use vergences to prevent diplopia and move the image
Prism over correction for ARC
Works well with younger children to disrupt ARC by stimulating the laten NRC localization
Phase I: over correct by about 15pd, for as long during the day
This includes diplopia so the latent NRC localization can manifest
Consider cosmetic concerns
Consider rotleratce of the initial diplopia
Monitor patietn closely because of prism adaptation (same say 2.5x the objective angle)
Phase 2 of prism correction of ARC
After a few months and when NRC is repeatedly seen on after I mage, the needed power will be equal to the objective angle
Vergence therapy can be started
Prism can be gradually reduced as the patietn appears to habe mroe fusional vergence
If the angle is still large, surgery can be soldiered
Occlusion therapy for ARC
- ARC development is prevented if occlusion is started early enoug
- no evidence to show if it is effective for an already established ARC
- occlusion for amblyopia is done before occluding for ARC
- total occlusion for 24 hours on alternative day basis
- poor compliance
Reasons to use occlusion for ARC
- to disrupt ARC localization and prevent reinforcement
- to break suppression
- to treat amblyopia
Method and schedule off occlusion depends on age, condition
Constant total occlusion and ARC
For children with constant strabismus that started before the age of 7
Be cautious in cases of intermittent strab because occlusion strab can result
Binasal occlusoin in ARC
Can be used in children with ER to prevent and treat any ARC
Allows
- alternator monocular fixation
- equal VA
- use of peripheral fields
- full abduction to break ARC
Consider
- active children
- children with large head movements for fixation
VT for ARC
- anti suppression therapy, amblypscope, stereoscopes can be used
- this forces the strab eye to fixate
- work on motor ranges as well
Surgery for ARAC
- some pateitns may report NRC after surgery, especially those with mildly embedded ARC
- NRC, ARC covariance or paradoxical UHARC may result after surgery because of the new alignment
Width of the occluder in binasal occluder
Larger in the fixating eyes
Other treatment considerations for ARC
- major amblyoscope is a good closed-space instrument (less natural). After there is training here, skills are transferred into open space
- it is to elicit bifvoeal NRC localization by stimulating latent NRC
- done in addiction to constant total occlusion or prism (to disrupt ARC)
- use the amblyoscope first before doing free space skills
Free space skills for ARC
Binocualr luster (R/G fusion) training: should report mixture of the colors or rivalry
If the patietn reports a split field repsosne in BV luster training
Prognosis for treatment is poor because the ARC is deeply imbedded
Pateitn instructed to maintain luster while targets are introduced to the periphery, plus lenses are introduced, etc
Other training for free space skills in ARC
Afterimage training
Haidinger brush training
Bagolini training
