Effect of Accommodative Adaptation on Static and Dynamic Accommodation in Emmetropia and Late-Onset Myopia

Dynamics of Accommodative Facility in Myopes

“…The results of both objective and subjective monocular accommodative facility measurements are in agreement with previous studies 5,8,21 which demonstrate that myopes exhibit a significantly lower accommodative facility rate when compared with emmetropes for distance viewing conditions but not for near tasks. The objective and subjective measurements of positive (Pearson correlation ϭ 0.995) and negative (Pearson correlation ϭ 0.996) response times correlated well with each other in all the subjects and their dependence on test distance and refractive group was similar to that found in earlier work.…”

“…The objective and subjective measurements of positive (Pearson correlation ϭ 0.995) and negative (Pearson correlation ϭ 0.996) response times correlated well with each other in all the subjects and their dependence on test distance and refractive group was similar to that found in earlier work. 21 In principle, the task presented for the measurement of accommodative facility should be an easy one, since the subject decides when the target vergence should be changed, making the task entirely predictable and minimizing true ac-commodation latencies. 33,34 Nevertheless, the mean cycle times of 3 seconds or more (corresponding to 0.3 Hz or less) were much longer than might be expected merely on the basis of typical step response times (usually Ͻ1 second 23,26 ) or the known ability of the accommodation system to respond at frequencies of up to approximately 2 Hz.…”

“…Refractive error has been shown to have an effect on various accommodation measurements 5 including accuracy of the accommodative response, 6 -8 the accommodative convergence to accommodation ratio, 9 -12 tonic accommodation, 10,[13][14][15] and nearwork-induced transient myopia. 16 -20 Jiang and White 21 investigated the effect of refractive error on accommodative facility and found that monocular accommodative facility at near was not significantly influenced by refractive error. However, when the data were broken down into positive and negative response times, the difference between refractive groups in the time taken to relax accommodation (negative response time) was significant, with myopes having shorter negative accommodation times.…”

Accommodative Responses Under Different Stimulus Conditions

“…Therefore, the AS sequence should be considered in the ASRC measurement, and a randomized paradigm 33 should be recommended to avoid such kind of effect. Therefore, the AS sequence should be considered in the ASRC measurement, and a randomized paradigm 33 should be recommended to avoid such kind of effect.…”

Accommodative Facility in Eyes with and without Myopia

“…In essence, the lack of an accurate accommodative response equates to periods of retinal defocus or blur, and it has been well documented using animal models that retinal defocus leads to increased eye growth and myopia. 9 -11 Various measures of accommodation such as amplitude of accommodation, tonic accommodation, accommodative adaptation, accommodative stimulus response curves, and near-work-induced transient myopia have been investigated, [12][13][14][15][16][17][18][19] and there is growing evidence from these studies to suggest that errors of accommodation are associated with myopia. [13][14][15] Despite these findings, however, the mechanism by which accommodation could affect the development of myopia is not fully understood and, of importance, there is no single measure of accommodation that can be used to predict an association with myopia.…”