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.

1. Principles of
Strabismus
Management
Part 1 of 3
ALVINA PAULINE D. SANTIAGO, MD
MAY 9, 2020
https://youtu.be/DrZZhK24qeI?t=13

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

11. Ensuring repeatability
Refractive
error
Accommodative
target
Cover Test
Distance
1o & 2o
deviations