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E. E. Birch, D. R. Stager, Sr., D. R. Stager, Jr., P. M. Berry; Risk Factors for Esotropic Amblyopia. Invest. Ophthalmol. Vis. Sci. 2007;48(13):1108.
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While it is well known that amblyopia is associated with both infantile and accommodative esotropia, factors that may increase risk for amblyopia have not been identified. Identification of risk factors may provide guidance in determining which esotropic patients may benefit from frequent visits to promote early detection and prompt treatment of amblyopia.
Consecutive patients were enrolled at the time of their initial diagnosis and included if followed through visual maturity (mean age = 9.5 y); 91 had infantile esotropia (IET) and 39 had accommodative esotropia (AET). For risk analyses, patients were grouped as never amblyopic, recovered amblyopic, and persistent amblyopic. Age of onset of ET, delay in referral, initial refractive error, initial anisometropia, and (for IET only) age at surgery were examined as risk factors.
Overall, 80.2% of children with IET and 74.4% of children with AET had amblyopia at some point during follow-up. The mean age at onset of amblyopia was 13.6 m for IET and 36.8 m for AET, 10-11 m after the onset of ET. Despite treatment, 22.0% of children with IET and 33.3% of children with AET remained amblyopic. A significant linear trend for delay in referral was found among the amblyopia groups, for both IET and AET (IET: never=1.8 m, recovered=2.7 m, persistent=4.3 m, F1,89=14.1, p=0.0003; AET: never=1.7 m, recovered=3.6 m, persistent=5.4 m, F1,37=12.6, p=0.001). All pairwise comparisons were statistically significant (p<0.04). The relative risk for amblyopia that persists despite treatment was more than doubled if the delay in referral was ≥3 m. A significant linear trend for anisometropia was also found among the amblyopia groups (IET: never=0.10D, recovered=0.31D, persistent=0.48D, F1,89=7.0, p=0.01; AET: never=0.08D, recovered=0.59D, persistent=1.35D, F1,37=11.06, p=0.002). Interestingly, anisometropia was related to the delay, with greater anisometropia in children who had a delay in referral ≥ 3 m (IET: t=2.06, p<0.02; AET: t=2.98, <0.002). Age at onset, refractive error, and age at surgery were not found to be associated with risk for amblyopia.
Both delay in referral and anisometropia increase the risk for development of persistent amblyopia in children with infantile or accommodative ET. These factors may be inter-related.
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