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Yilei Shao; Axial length and dynamic disaccommodation changes accompanying prolonged near work. Invest. Ophthalmol. Vis. Sci. 2018;59(9):2951.
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To investigate the time course and recovery of the axial elongation and changes in the disaccommodative function associated with a 20 min near work task.
A custom built ultra-long scan depth optical coherence tomography (UL-OCT) was used to image the eyes from cornea to retina for measurement of the axial length (AL) before the near work task (PRE-0D). Then a 5.0D accommodative stimulus was given by a Badal optical system which was combined with the UL-OCT, and the axial length was measured at the start of (PRE-5D) and 20 min after (POST-5D) the near work task. Immediately following the completion of the task (POST-0D) and after a 10 min rest period (REST-0D), the axial length was measured again. Moreover, before (PRE-0D) and immediately after the task (POST-0D), a 5.0D-disaccommdative process was measured by using an auto-refractor. An emmetrope (spherical equivalence, SE = -0.50D) and a high myope (SE = -8.00D) were enrolled in this pilot study. The changes in axial length and the peak velocity of disaccommodation during the task and the recovery period were calculated.
Changes in axial length during the task were comparable between the emmetrope and the high myope (emmetrope: 47 µm at PRE-5D and 47 µm at POST-5D; high myope: 48 µm at PRE-5D and 41 µm at POST-5D, Fig. 1). After the task, high myope showed slower recovery in axial elongation (35 µm at POST-0D and 25 µm at REST-0D) compared with emmetrope (13 µm at POST-0D and -3 µm at REST-0D). For emmetrope, the peak velocity of disaccommdation changed slightly before and after the task (5.82 D/s vs. 6.32 D/s). On the contrary, the velocity of high myope after the task showed much slower than that before the task (1.49 D/s vs. 0.54 D/s).
We successfully acquired changes in the axial length and dynamic disaccommodation in an emmetrope and a high myope. Compared with emmetropia subject, high myope showed slowing in recovery of the axial elongation and the disacommodative function associated with prolonged near work.
This is an abstract that was submitted for the 2018 ARVO Annual Meeting, held in Honolulu, Hawaii, April 29 - May 3, 2018.
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