Accommodation Responds to Optical Vergence and Not Defocus Blur Alone

作者：Del Aguila Carrasco Antonio J^*; Marin Franch Ivan; Bernal Molina Paula; Esteve Taboada Jose J; Kruger Philip B; Montes Mico Robert; Lopez Gil Norberto

来源：Investigative Ophthalmology & Visual Science, 2017, 58(3): 1758-1763.

DOI：10.1167/iovs.16-21280

• accommodation
• defocus blur
• vergence
• adaptive optics
• dynamic accommodation

PURPOSE. To determine whether changes in wavefront spherical curvature (optical vergence) are a directional cue for accommodation.
METHODS. Nine subjects participated in this experiment. The accommodation response to a monochromatic target was measured continuously with a custom-made adaptive optics system while astigmatism and higher-order aberrations were corrected in real time. There were two experimental open-loop conditions: vergence-driven condition, where the deformable mirror provided sinusoidal changes in defocus at the retina between -1 and +1 diopters (D) at 0.2 Hz; and blur-driven condition, in which the level of defocus at the retina was always 0 D, but a sinusoidal defocus blur between -1 and +1 D at 0.2 Hz was simulated in the target. Right before the beginning of each trial, the target was moved to an accommodative demand of 2 D.
RESULTS. Eight out of nine subjects showed sinusoidal responses for the vergence-driven condition but not for the blur-driven condition. Their average (+/- SD) gain for the vergence-driven condition was 0.50 (+/- 0.28). For the blur-driven condition, average gain was much smaller at 0.07 (+/- 0.03). The ninth subject showed little to no response for both conditions, with average gain <0.08. Vergence-driven condition gain was significantly different from blurdriven condition gain (P = 0.004).
CONCLUSIONS. Accommodation responds to optical vergence, even without feedback, and not to changes in defocus blur alone. These results suggest the presence of a retinal mechanism that provides a directional cue for accommodation from optical vergence.

• 出版日期2017-3