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

Abstract

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 through-focus subjective quality of vision curves (AUC).

Results: On average, viewing through a combination of 0.4 μm of SA4 and -0.2 μm of SA6 with one eye and through a combination of -0.4 μm of SA4 and 0.2 μm 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.

Keywords: Optics and Refraction; Vision.