June 2013
Volume 54, Issue 15
Free
ARVO Annual Meeting Abstract  |   June 2013
Concordance with occlusion therapy for childhood amblyopia
Author Affiliations & Notes
  • Michael Wallace
    Optometry and Visual Science, City University, London, United Kingdom
  • Catherine Stewart
    Optometry and Visual Science, City University, London, United Kingdom
  • Merrick Moseley
    Optometry and Visual Science, City University, London, United Kingdom
  • David Stephens
    Mathematics and Statistics, McGill University, Montreal, QC, Canada
  • Alistair Fielder
    Optometry and Visual Science, City University, London, United Kingdom
Investigative Ophthalmology & Visual Science June 2013, Vol.54, 4979. doi:
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    • Get Citation

      Michael Wallace, Catherine Stewart, Merrick Moseley, David Stephens, Alistair Fielder, MOTAS and ROTAS cooperative; Concordance with occlusion therapy for childhood amblyopia. Invest. Ophthalmol. Vis. Sci. 2013;54(15):4979.

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      © ARVO (1962-2015); The Authors (2016-present)

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Abstract
 
Purpose
 

The Monitored and Randomized Occlusion Treatment of Amblyopia Studies (MOTAS & ROTAS) used Occlusion Dose Monitors to measure objectively occlusion. Here we examine factors influencing concordance with prescribed occlusion dose.

 
Methods
 

Studies had a 3-phase protocol: initial assessment, refractive adaptation and occlusion. Occlusion therapy proceeded refractive adaptation for those with unresolved amblyopia. Participants were instructed to dose for 6 hrs/day (MOTAS) or randomized to 6 or 12 hrs/day (ROTAS). Occlusion was monitored at ≈1 min intervals during treatment, and dose data downloaded for analysis during 2-weekly follow-up clinic visits.

 
Results
 

152 patients (mean;sd age 65;18 months) received occlusion. Amblyopia was associated with anisometropia in 50, strabismus in 44, and both (mixed) in 58. Median follow-up was 99 days (IQR 72 days). Mean concordance was 44%, mean proportion of days with zero occlusion was 42%. Concordance at weekends was lower than on weekdays (p=0.039) as was the likelihood of dosing at all (p=0.028). Concordance was lower, and dosing on any given day less likely, the later into follow-up dosing occurred and with less frequent clinic visits (all p<0.001). Those prescribed 6 hours of occlusion had lower concordance (p=0.033) than those prescribed 12, but both groups were equally likely to dose at all on a given day. Age, gender, amblyopia type and severity were not associated with concordance. Among non-zero daily occlusion doses, mixture modelling indicated three underlying subpopulations: doses of usually under 10% concordance; doses of usually 30%-80% concordance; and doses of usually near-100% concordance.

 
Conclusions
 

Concordance is strongly influenced by the frequency of days with zero dose, which are more likely at weekends and increasingly frequent over time in follow-up. Minimizing such days should be a priority if attempting to boost concordance (e.g. if participants had received their mean non-zero daily dose on half of the days where they did not dose at all, overall concordance would have been 57% rather than 44%).

 
 
Mean daily concordance with prescribed dose across all individuals still in treatment. Days with fewer than 10 individuals not shown.
 
Mean daily concordance with prescribed dose across all individuals still in treatment. Days with fewer than 10 individuals not shown.
 
 
Bars: non-zero daily dose concordance distribution across all individuals. Lines: components of 3-part normal mixture model (fit to log-transform of data). Legend percentages: estimated proportion of daily doses in each component distribution.
 
Bars: non-zero daily dose concordance distribution across all individuals. Lines: components of 3-part normal mixture model (fit to log-transform of data). Legend percentages: estimated proportion of daily doses in each component distribution.
 
Keywords: 417 amblyopia • 466 clinical (human) or epidemiologic studies: treatment/prevention assessment/controlled clinical trials • 473 computational modeling  
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