Subjective through-focus quality of vision with various versions of modified monovision

Background/aims To evaluate and compare the effect of various modified monovision on binocular through-focus quality of vision. Methods Simulated images were computed using a numerical eye model, with a 4.7 mm pupil diameter, for various target vergences and with various combinations of spherical (SA4) and secondary spherical (SA6) aberrations. Binocular vision was provided using a video projector synchronised with active glasses. Three subjects evaluated monocular and binocular through-focus images by scoring the displayed image with a five-item continuous grading scale. Performance was evaluated in terms of depth-of-focus and area under the throughfocus subjective quality of vision curves (AUC). Results On average, viewing through a combination of 0.4 mu m of SA4 and -0.2 mu m of SA6 with one eye and through a combination of -0.4 mu m of SA4 and 0.2 mu m of SA6 with the other eye, improved depth-of-focus and AUC, respectively, by 193% and 71% compared with naked eyes. Binocular summation occurred when both eyes viewed comparable image quality, whereas the level of binocular inhibition increased with the interocular difference of image quality. Conclusions Binocular performance could be optimised by choosing different multifocal profiles for each eye and by adding a defocus term between eyes.