Correction of Low-Moderate Hyperopia Improves Accommodative Function for Some Hyperopic Children During Sustained Near Work

Abstract

Purpose: This study investigated whether refractive correction improved accommodative function of hyperopic children while engaged in two sustained near activities.

Methods: Sustained accommodative function of 63 participants (aged 5-10 years) with varying levels of uncorrected hyperopia (>/= +1.00 D and < + 5.00 D spherical equivalent in the least hyperopic eye) was measured using eccentric infrared photorefraction (PowerRef 3; PlusOptix, Germany). Binocular accommodation measures were recorded while participants engaged in 2 tasks at 25 cm for 15 minutes each: an "active" task (reading small print on an Amazon Kindle), and a "passive" task (watching an animated movie on liquid crystal display [LCD] screen). Participants also underwent a comprehensive visual assessment, including measurement of presenting visual acuity, prism cover test, and stereoacuity. Reading speed was assessed with and without hyperopic correction. Refractive error was determined by cycloplegic retinoscopy.

Results: Hyperopic refractive correction significantly improved accuracy of accommodative responses in both task (pairwise comparisons: t = -3.70, P = 0.001, and t = -4.93, P < 0.001 for reading and movie tasks, respectively). Accommodative microfluctuations increased with refractive correction in the reading task (F(1,61) = 25.77, P < 0.001) but decreased in the movie task (F(1,59) = 4.44, P = 0.04). Reading speed also significantly increased with refractive correction (F(1,48) = 66.32, P < 0.001).

Conclusions: Correcting low-moderate levels of hyperopia has a positive impact on accommodative performance during sustained near activity in some schoolchildren. For these children, prescribing hyperopic correction may benefit performance in near vision tasks.

Figure 1.

A schematic diagram of operation of the PowerRef 3 infrared photorefraction system, which used two periscopic hot/cold mirrors to reflect infrared light from the instrument's camera aperture into the eye, to enable the reading and movie tasks to be viewed directly on visual axis. The entire table was tilted by 16.7 degrees to enable participants to view in downgaze, thus adopting a more natural reading position.

Figure 2.

(A) An example of the accommodative response over time in the reading task showing apparent variation in response when participant was reading the top and bottom of the Kindle screen, in up and down-gaze positions. (B) The same accommodative response after data points corresponding to these outliers in panel A were removed. The Y-axis represents refraction (from which the accommodative response was computed), and the X-axis represents the length of the data samples (from which the duration of measurement can be derived, given the 50 Hz sampling frequency of the PowerRef 3).

Figure 3.

(A) Effect of hyperopic refractive correction on the stability of the accommodative response in the reading task, calculated as the difference between the root mean square error (RMSE) of the accommodative response with and without correction. (B) Effect of correction on the stability of the accommodative response in the movie task, calculated as the difference between the RMSE of the accommodative response with and without correction. The long-dashed line represents no effect of correction (difference of zero). Data points above long-dashed line represent more accommodative response instability with correction, while those below line represents less instability with correction.

Figure 4.

Improvement in reading speed with hyperopic refractive correction. This was calculated as the difference between the reading speed score with and without correction. Long-dashed line represents no effect of correction (difference of zero). Data points above line represent improvement in reading speed with correction.