intraday variability of control in intermittent exotropia
DESCRIPTION
Intraday Variability of Control in Intermittent Exotropia. Sarah R. Hatt, Brian G. Mohney, David A. Leske, Jonathan M. Holmes Mayo Clinic, Rochester, MN, USA. Commercial relationships: None. Poor control: > 50% of waking hours Deterioration – consecutive visits: indicator for surgery - PowerPoint PPT PresentationTRANSCRIPT
Commercial relationships: None
Intraday Variability of Control in Intermittent Exotropia
Sarah R. Hatt, Brian G. Mohney, David A. Leske, Jonathan M.
Holmes
Mayo Clinic, Rochester, MN, USA
Intermittent Exotropia - Control• Poor control:
> 50% of waking hours
• Deterioration – consecutive visits: indicator for surgery
• Type and degree of variability of control within 1 day is not known
Implications for: • defining severity• interpreting change in control over time
Purpose
To assess the variability of control over one day
in children with intermittent exotropia
using control scale to quantify control
Methods – Control AssessmentControl Score Control Score Description
5 Constant exotropia during a 30-second observation period (before dissociation)
4 Exotropia >50% of the time during a 30-second observation period (before dissociation)
3 Exotropia <50% of the time during a 30-second observation period (before dissociation)
2 No exotropia unless dissociated (10 seconds): recovery in > 5 seconds
1 No exotropia unless dissociated (10 seconds): recovery in 1-5 seconds
0 Pure phoria: < 1 second recovery after 10-second dissociation
Mohney BG, Holmes JM. An office-based scale for assessing control in intermittent exotropia. Strabismus 2006;14:147-50.
Control scale reliability near control k=0.95 distance control k=0.94
Inve
stig
ato
r 2
Investigator 1
0
1
2
3
4
5
0 1 2 3 4 5In
vest
iga
tor
2Investigator 1
0
1
2
3
4
5
0 1 2 3 4 5
Scores differed by no more than one level on the control scale:
Real change in control defined as change of 2 or more levels on scale.
Methods – Intraday variability
• 13 children with intermittent exotropia (median age 8 years; range 1 to 13) No convergence insufficiency type exotropia
• No co-existing ocular pathology
• No amblyopia
Methods – Intraday variability
Examined 3 or 4 times over one day
(minimum 2 hours apart)
Control assessed using control scale
Variable = change in control 2 or more levels on control scale over day (distance or near)
Stable = no change in control over day
10:31-13:008:00 -10:30 13:01-15:30 15:31-18:00
Results – Intraday variability of control
Median angle - near
30^26^Median angle - distance
11Median control - near
20^25^
1*2.75Median control - distance
7.2 years7.3 yearsMean age
Stable control
7/13 (54%)
Variable control
6/13 (46%)N=13
* p=0.04
Patient 1
Patient 10
Patient 13
Results – Variable distance control
Assessment time
Con
trol
sca
le r
atin
g
0
1
2
3
4
5
8:00 -10:30 10:31-13:00 13:01-15:30 15:31-18:00
Tro
pic
Ph
oric
0
1
2
3
4
5
8:00 -10:30 10:31-13:00 13:01-15:30 15:31-18:00
Patient 3
Patient 5
Patient 11
Patient 13
Results – Variable near control
Assessment time
Con
trol
sca
le r
atin
g
Ph
oric
Tro
pic
Results – Summary
• Control varies over one day in some patients with intermittent exotropia.
• Change occurs between spontaneous tropia and well controlled phoria.
• Worst control not always at the end of the clinical day.
Change in distance control
0
1
2
3
4
5
January April August
Assessment time
Con
trol
sca
le r
atin
g
Tro
pic
Ph
oric
10:30
12:45 14:49
Conclusions• An isolated measure of control may be insufficient
to represent: baseline severity change over time.
• If control has a role in evaluating severity, multiple measures will be needed.
• Change in isolated measures of control should not be used for surgical decision making.
Thank You
Supported by:
EY015799 (JMH)
Research to Prevent Blindness, Inc.