Российский офтальмологический журнал (Mar 2019)
An objective study of negative accommodation
Abstract
Purpose: to study the dynamic refraction of myopic eyes at the time when the object is fixed in an open field at a distance of 5 m and determine habitual accommodation tone (HAT) in an open field. Material and methods. 130 patients (260 eyes) aged 6 to 23 years (ave. 11.26 ± 0.2 years) with an average refraction spherical equivalent of -4.16 ± 0.13 D were divided into 4 groups, depending on the degree of myopia. The HAT was measured by an automatic binocular open field (OP) autorefkeratometer Grand Seiko WR-5100K (Japan), while the HAT according to Yuri Rosenblum was determined by a conventional autorefractometer Nidek. Results. Comparing noncycloplegic and cycloplegic refraction using the two devices, we obtained different results. In the first case, we found the maximal difference of -0.15 D (-4.38 – (-4.23)), and in the second case, the minimal difference of -0.09 D (-4.16 – (-4.07)). Over the whole group, HAT according to Yuri Rosenblum averaged -0.21 ± 0.02 D. In patients with low myopia HAT was the highest and averaged -0.33 ± 0.03 D. In patients with moderate myopia an average HAT level was -0.23 ± 0.03, and in high myopia it was -0.19 ± 0.04 D. Patients with anisomyopia showed a significant difference of the tone between the fellow eyes: the eyes with lower refraction showed a HAT of -0.21 ± 0.03 D, while for the worse eye it was 0.06 ± 0,11 D (p < 0.05) (i.e. a negative accommodation tone). Over the whole contingent HAT OP averaged -0.17 ± 0.02 D: in patients with low myopia it averaged -0.22 ± 0.04 D, in those with moderate myopia, -0.27 ± 0.02 D, in high myopia — -0.09 ± 0.04 D. PTA OP patients with anisomyopia averaged -0.07 ± 0.03 D and demonstrated a significant difference between the eyes (-0.26 ± 0.03 D for the better eyes and 0.12±0.06 D — for the worse eyes, p < 0.01). A negative tone of accommodation of HAT OP in myopia occurs, on average, in 30% of patients; the frequency was maximal in high myopia (50 %) and minimal in moderate myopia (13.8 %). Conclusions. Objectively determined the weakening of the far dynamic refraction as compared with the static refraction (in terms of cycloplegia) was objectively determined. Thus, the existence of negative accommodation was confirmed.
Keywords
