To compare the clinical characteristics relevant to the ability to accommodate in patients with intermittent exotropia (IXT) concomitant with myopia or non-myopia.

This was a retrospective clinical study. Forty IXT patients between 6 and 15 years old were recruited from Beijing Tongren Hospital between December 2019 and January 2020. Of these, 20 patients were diagnosed with both IXT and myopia, while the other 20 patients were diagnosed with IXT and non-myopia. The evaluation parameters were refractive errors, dominant eyes, strabismus angle, AC/A, accommodative response (normal, accommodative lag, and accommodative lead), accommodative amplitude, and negative/positive relative accommodation. The revised Newcastle Control Score (RNCS) method was used to evaluate the ability to control exotropia. A paired t-test for dependent samples was used for comparison between the two eyes in each group and a two-sample t-test and nonparametric test were used to compare data between the two groups. Categorical data were compared using Fisher's exact test or aχ² test.

The AC/A (2.78±1.09) of the myopia group was significantly lower than that of the non-myopia group (3.93±1.99) (t=-2.263, P=0.029). The accommodative amplitudes for the dominant eye (6.77±2.42) and non-dominant eye (6.52±2.16) in the myopia group were both lower than those for the dominant eye (9.14±2.89) and non-dominant eye (8.07±2.60) in the non-myopia group (t=-2.80, P=0.008; t=-2.05, P=0.047). The accommodative amplitude of the dominant eyes was significantly higher than the non-dominant eyes in the non-myopia group (t=2.572, P=0.019). The differences in accommodative amplitudes between the two eyes in the myopia group were not statistically significant. No significant differences were found in the positive relative accommodation, negative relative accommodation or accommodative response. The RNCS in the IXT combined with myopia group (7.20±1.96) was significantly higher than that in the non-myopia group (5.50±2.83) (t=2.203, P=0.034).

Changes in accommodative characteristics are important indicators for the onset and progression of myopia, including a decline in AC/A and a decrease in accommodative amplitudes in the dominant and non-dominant eyes and a trend to balance between the two eyes.

intermittent exotropia; accommodative ability; myopia