Bifocals Fail to Improve Stereopsis Outcomes in High AC/A Accommodative Esotropia

Abstract

Purpose: To assess whether stereopsis outcomes of patients with accommodative esotropia with high accommodative convergence/accommodation relationship (AC/A) were improved after treatment with bifocal glasses compared with single-vision lenses.

Design: Retrospective cohort study.

Participants: Patients with high AC/A accommodative esotropia; evidence of stereopsis, binocularity (on Worth 4-dot testing), or improvement in near angle with +3.00 D lenses; and at least 4 years of records available for review, who were seen in the Department of Ophthalmology at Boston Children's Hospital between 2006 and 2014.

Methods: Use of bifocal or single-vision glasses. Charts were reviewed retrospectively. Stereopsis was log transformed for statistical analysis. Linear (for stereopsis) or logistic (for surgery) regression was used to control for confounders.

Main outcome measures: Stereopsis at final follow-up, difference in stereopsis between final and initial visits, and progression to strabismus surgery. Secondary outcomes included final near and distance deviations.

Results: Of the 180 patients who met inclusion criteria, 77 used bifocals and 103 used single-vision lenses. Bifocals did not improve stereopsis outcomes compared with single-vision lenses. In both groups, stereopsis was similar at the initial and final visits, with similar improvement in both groups. Children in the bifocal group had a 3.6-fold higher rate of strabismus surgery than children in the single-lens group (P = 0.04.) Additionally, children in the bifocal group had near deviations 4 PD larger than those with single lenses at final follow-up, even after controlling for age and initial deviation (P = 0.02). These results did not change if surgical patients were eliminated or in the subgroup with initial distance deviation of 0 PD in full hyperopic correction.

Conclusions: Despite their widespread use, there is no evidence that bifocals improve outcomes in children with accommodative esotropia with high AC/A. In our retrospective review, children with bifocals had higher surgical rates and a smaller improvement in near deviation over time. Although our results suggest that eliminating bifocals could reduce the cost and complexity of care while potentially improving quality, prospective, randomized controlled trials are needed to determine whether a change in practice is warranted.

Figure 1

Stereopsis outcomes of bifocal and single vision lens groups. A. Neither initial stereopsis measurements nor final stereopsis measurements differed between the groups, although both groups saw significant improvement over the period of follow-up. B. Box-and-whisker plot showing individual changes in stereopsis between initial and final visits. Stereopsis was log transformed to facilitate mathematical calculations. See Table 1 to transform logArcsec to arcsec. [In the box-and-whiskers plots, the bottom and top of each box represent the 25th and 75th percentiles (the lower and upper quartiles, respectively); the band near the middle of the box is the 50th percentile (the median), the × marks the mean value. The whiskers are based on the Tukey method. The upper whisker is the smaller of the 75^th percentile plus 1.5 times the interquartile range (IQR), or the maximum value. The lower whisker is the larger of the 25^th percentile minus 1.5 times the IQR or the minimum value. Values greater than 75^th percentile plus 1.5 IQR, or less than 25^th percentile minus 1.5 IQR are plotted as individual points. **p<0.01

Figure 2

Structural outcomes of bifocal and single vision lens group. A) Progression to surgery in bifocal group (dark bar) vs. single vision group (light bar). Adjusted odds ratio showed a 3.6-fold higher risk of progression to surgery in the bifocal group. (B), Box and whisker plot showing size of near esodeviation (measured at 1/3m through distance correction) at final follow-up. Single vision group had a significantly smaller angle. [In the box-and-whiskers plots, the bottom and top of each box represent the 25th and 75th percentiles (the lower and upper quartiles, respectively); the band near the middle of the box is the 50th percentile (the median), the × marks the mean value. The whiskers are based on the Tukey method. The upper whisker is the smaller of the 75^th percentile plus 1.5 times the interquartile range (IQR), or the maximum value. The lower whisker is the larger of the 25^th percentile minus 1.5 times the IQR or the minimum value. Values greater than 75^th percentile plus 1.5 IQR, or less than 25^th percentile minus 1.5 IQR are plotted as individual points. **p<0.05

Figure 3

Subgroup analysis of stereopsis outcomes after eliminating surgical patients (A) or restricting the analysis to patients orthophoric at distance (B). For A, patients who underwent surgery after the initial examination were excluded. For B, patients with residual microtropia at distance were excluded. No significant differences were found in stereopsis between bifocal and single vision groups. Stereopsis measurements were log transformed. See Table 1 to convert logArcsec to arcsec. In the box-and-whiskers plots, the bottom and top of each box represent the 25th and 75th percentiles (the lower and upper quartiles, respectively); the band near the middle of the box is the 50th percentile (the median), the × marks the mean value. The whiskers are based on the Tukey method. The upper whisker is the smaller of the 75^th percentile plus 1.5 times the interquartile range (IQR), or the maximum value. The lower whisker is the larger of the 25^th percentile minus 1.5 times the IQR or the minimum value. Values greater than 75^th percentile plus 1.5 IQR, or less than 25^th percentile minus 1.5 IQR are plotted as individual points.