Pablo Artal. collaborators. Adaptive Optics for Vision: The Eye's Adaptation to its Point Spread Function

Transcription

1 contrast sensitivity Adaptive Optics for Vision: The Eye's Adaptation to its Point Spread Function (4 th International Congress on Wavefront Sensing, San Francisco, USA; February 23) Pablo Artal LABORATORIO DE OPTICA UNIVERSIDAD DE MURCIA, SPAIN Campus de Espinardo (Ed.C), 37 Murcia, SPAIN LABORATORIO DE OPTICA UNIVERSIDAD DE MURCIA, SPAIN Murcia, SPAIN collaborators The quality of the retinal image imposes the first limit to VISION... Joshua Fernández Silvestre Manzanera Li Chen David Williams...but we do not know yet how to predict quality of VISION from the retinal image? spatial frequency (c/deg) = perceived (visual) image retinal image?

2 Adaptive Optics to PREDICT (or simulate) VISION! (VISUAL SIMULATOR) Principle of AO-visual simulator Wave-front generator + eye = modified eye University of Murcia, Opt.Lett., 2 University of Rochester, Opt.Express, 2 + = Principle of AO-visual simulator Wave-front generator eye modified eye AO-visual simulator concept + retinal images = wave-front generator real-time wave-front sensor Some applications of Adaptive optics as Spectra of Zernike modes with and without paralyzed accommodation for 4.7 mm pupil VISUAL SIMULATOR Interactive design/testing of new ophthalmic devices. Some applications of Adaptive optics as Spectra of Zernike modes with and without paralyzed accommodation for 4.7 mm pupil VISUAL SIMULATOR Predicting visual outcomes Simulation of vision previous permanent refractive surgery

3 Some applications of Adaptive optics as VISUAL SIMULATOR New experiments to better understand how aberrations affects quality of VISION Experiment : visual acuity with normal and modified aberrations real-time HS sensor monitor pupil control IR laser Wave-front generator 37 channels membrane deformable mirror from OKO (Holland).5.4 (µm) membrane deformable mirror motor (focus) LO UM_AO-visual simulator (µm) psychophysics monitor (stimulus) Testing visual acuity E EEE LO UM_AO-visual simulator (a general view)?

4 Induced aberrations (similar RMS; different shape) + = SIMILAR MTFs for normal and modified eyes MTF normal eye modified.5.5 Visual Acuity BUT DIFFERENT visual acuity.9 (2/22).3(2/5) normal Visual acuity modified naked eye Induced I Induced II Visual Acuity (Snellen) RMS= Not every aberration pattern, even similar in magnitude, appears to have the same impact in vision. The eye s own aberrations seems to provide the best visual performance. Is the visual system adapted to its own aberrations?

5 Experiment 2: Subjective blur matching with normal and rotated PSFs We used the University of Rochester AO system to rotate the eye's PSF! normal eye's aberrations normal eye's PSF adaptive optics + eye rotated aberrations rotated PSF

6 visual stimulus (sharp edges at no systematic orientation) real-time wave-front sensor Correct eye aberration & generate wave aberration Show stimulus Show stimulus reduction in RMS? deformable mirror superluminiscent diode 5ms Closed loop 5ms Closed loop Correct eye aberration & generate rotated θ wave aberration Adjust factor between to RMS reduction required for subjective blur matching (Subject PA) Rotated angle (deg) RMS reduction required for subjective blur matching (Subject PA) Rotated angle (deg) normal A parameter that provides information on the PSF symmetry: maximum of the cross-correlation function (MCC) degrees degrees rotated degrees 45 degrees rotated x.7

7 The asymmetry parameter (MCC) predicts well the measured subjective blur matching values (BMV) rotated angle (deg) BMV MCC RMS reduction required for subjective blur matching (Subject MC) Matching factor Rotated angle (deg) RMS reduction required for subjective blur matching (average four subjects) Subjective blur matching (average four subjects) Matching factor relative subjective blur % 2% Rotated angle (deg) Rotated angle In all the subjects tested, the RMS of the rotated wave aberration required to match the subjective blur with the normal wave aberration was 2 to 4% less; indicating that the subjective blur for the stimulus increased when their PSF was rotated. These results support the hypothesis that the neural visual system is adapted to the eye s particular aberrations.

8 The visual system is also adapted to contrast and blur, so it is not enterely surprising if it is also adapted to the particular high order aberration of the ocular optics. WARNING! This adaptation will reduce the immediate benefit of attempts to surgically produce diffraction-limited eyes! normal PSF diffraction-limited PSF retinal image perceived image However, we do not know yet the temporal scale of this adaptation mechanism and when or how can be reversed. Further exciting experiments using ADAPTIVE OPTICS are required!!