The Comparison of Accommodative Response and Accommodative Lag Among Different Luminance of Near Visual Media

Abstract

This study was conducted to compare and analyze the effect of near visual media luminance on accommodative response (AR) and accommodative lag (AL) between emmetropia and myopia, and found out the near visual media to be caused burdensome on eyes in terms of AR and AL. Methods: Forty adult men and women (40 eyes) with ages averaging 22.57±2.07 years, who were not accommodative function disorder. 11 adults were emmetropes (average spheric equivalent power-0.34±0.22 D) and 29 adults were myopes (average spheric equivalent power-3.86±1.69 D). AR was measured and compared by using both eyes open view auto refractometer in the case looking at the near visual media (near standard target, print paper, newspaper, magazine, smartphone, monitor). Results: AR was lower and AL was higher in the case looking at the luminous visual media (smartphone, monitor) than the non-luminous visual media (near standard target, print paper, newspaper, magazine). AR (F=2.622, P=0.033) and AL (F=2.593, P=0.034) among different luminance of near visual media in emmetropes wear not statistically significant, However, AR was the lowest as 1.32±0.26 D (F=5.924, P=0.000), AL was the highest as 0.90±0.24 D (F=6.007, P=0.000) in the case looking at the monitor with the highest luminance and the widest screen size in myopes. Conclusions: When the myopes looking at the luminous visual media which includes high luminance and wide screen size is considered to be more burdensome on eyes than the emmetropes looking at the luminous visual media in terms of AR and AL.

Greater axial elongation associated with low accommodative lag: new insights on accommodative lag theory for myopia

“…[31][32][33] While it is expected that accommodative adaptation should be similar for both reading tasks, other factors such as differences in target luminance, pixel format and spatial frequency of the content could have led to a lower accommodative lag while reading text from a paper than the smartphone. 16,17 The findings of the current study are in general agreement with Mallen et al 34 where the changes in axial length under the influence of accommodation were shown to be dependent on the level of accommodative demand, with a significant increase in axial length being found only at a high accommodative stimulus of 6D (p = 0.02), and not at 2D (p = 0.27) or 4D (p = 0.08). In this study, we found that the magnitude of axial length change after different visual tasks was dependent on the properties of the near stimulus resulting in different levels of response, and hence a significant difference in axial length change across the visual tasks (p = 0.02).…”

“…Consistent with the previous literature, 15,16,19 this study found that the accommodative response varied with the type of near target. A higher lag of accommodation was observed when watching a video (≈0.90 D) compared with reading text from a smartphone (≈0.50 D) or on paper (≈0.25 D).…”

“…Instead, we found that near targets causing a lower lag of accommodation (reading text on a paper and smartphone) resulted in a small but significant increase in axial length in comparison with watching a video on smartphone which was associated with greater lag of accommodation. Consistent with the previous literature, 15,16,19 this study found that the accommodative response varied with the type of near target. A higher lag of accommodation was observed when watching a video (≈0.90 D) compared with reading text from a smartphone (≈0.50 D) or on paper (≈0.25 D).…”

“…13 Evidence from earlier studies investigating the accommodative response with different near targets suggests that accommodative response not only varies with target distance, but also with various properties of the stimulus, especially the type of material and content. [14][15][16][17][18] For example, watching videos on digital screens for a short duration is reported to cause a higher lag of accommodation than reading from a paper (hardcopy). 15,16,19 However, reading text from a paper leads to a similar lag of accommodation as when reading from a smartphone.…”

“…[14][15][16][17][18] For example, watching videos on digital screens for a short duration is reported to cause a higher lag of accommodation than reading from a paper (hardcopy). 15,16,19 However, reading text from a paper leads to a similar lag of accommodation as when reading from a smartphone. 20 Intriguingly, previous studies investigating the effect of shorter duration of accommodation on axial length, 21,22 or the lag of accommodation with different digital/non-digital near targets, 15,16,19 have failed to explain whether the changes in axial length during accommodation are caused by central hyperopic defocus associated with a higher lag of accommodation, or mechanical stress caused by the contraction of the ciliary muscle.…”