This document discusses factors that affect strabismus measurements and ensuring repeatability of measurements. It outlines the goals of strabismus surgery as determining target angles for surgery and recommending surgery using a strabismus surgical dose table. The document also describes techniques for horizontal strabismus surgery including recession, resection, and plication procedures.
2. Outcomes
Know factors affecting strabismus measurements
Enumerate requirements for repeatability of measurements
Discuss the goals of strabismus surgery
Determine target angles for surgery
Recommend surgery using a strabismus surgical dose table
Enumerate weakening and strengthening procedures
Describe technique for horizontal strabismus surgery:
recession, resection, plication
3. Factors affecting strabismus
measurements: Testing factors
Distance between
patient and target
http://www.adventuresetup.com
Monocular
occlusion
https://i.pinimg.com/474x/e2/7f/54/e27f
5495bc8b636156d847f0774dbf5f.jpg
Prism placement
Rosenbaum & Santiago 1999
4. The Ideal Target
®Maximum plus, least minus correction
®Allows minimal accommodation at 6 m
®Accommodation exerted only 1/6 m,
considered zero for strabismus
measurement purposes
5. The Ideal Target
® Above threshold
® e.g. Snellen acuity 20/20
® present 20/50
6. The Ideal Target
® With sufficient detail and contour
® Should sustain interest
7. Toys as Targets
® One toy one look
® With detail
® May be coupled with a
light
® Sounds for tracking but
not vision testing
8. Factors Affecting Measurement
® Method of testing:
® Light reflex:
® Bruckner
® Hirschberg
® Krimsky/modified Krimsky
® Different cover tests
® Cover Test
® Alternate Cover Test
9. ALTERNATE PRISM & COVER TEST
Gold standard for
measuring
deviation
LIGHT REFLEX, COVER TESTS
(Courtesy of R. Pena, MD)
10. Factors affecting strabismus
measurements: Patient factors
u Accommodation:
correcting refractive error
u AC/A ratio
u Uncorrected refractive
errors
u High refractive errors
u Neurological disorders
u CP, MG, PEO
u Thyroid orbitopathy
u Amblyopia
u Eccentric fixation
u Angle kappa
u Primary and secondary
deviations
u Axial length & Globe size
u Paresis vs Palsy
u Paresis vs. Restriction