A display system comprising: a head-mountable display configured to project light to a viewer to display a virtual object on one or more depth planes, the display comprising: one or more waveguides configured to project the light to the viewer, wherein the one or more waveguides are further configured to transmit light from objects in a surrounding environment to the viewer; a first variable focus lens element between the one or more waveguides and a first eye of the viewer; a second variable focus lens element between the one or more waveguides and the surrounding environment; and an eye tracking system configured to determine vergence of the viewer's eyes, wherein the display system is configured to: determine a depth of the vergence of the viewer's eyes; cause the first variable focus lens element to modify a wavefront divergence of the projected light for forming the virtual object on a depth plane, wherein an amount of the modification of the wavefront divergence is based on the determined depth of the vergence of the viewer's eyes and on an amount to correct a refractive error of the viewer's first eye, and cause the second variable focus lens element to modify a wavefront divergence of incoming light from the object in the surrounding environment on a depth plane, wherein an amount of the modification of the wavefront divergence is based on the determined depth of the vergence of the viewer's eyes and on an amount to correct the refractive error of the viewer's first eye. a head-mountable display configured to project light to a viewer to display a virtual object on one or more depth planes, the display comprising: one or more waveguides configured to project the light to the viewer, wherein the one or more waveguides are further configured to transmit light from objects in a surrounding environment to the viewer; a first variable focus lens element between the one or more waveguides and a first eye of the viewer; a second variable focus lens element between the one or more waveguides and the surrounding environment; and one or more waveguides configured to project the light to the viewer, wherein the one or more waveguides are further configured to transmit light from objects in a surrounding environment to the viewer; a first variable focus lens element between the one or more waveguides and a first eye of the viewer; a second variable focus lens element between the one or more waveguides and the surrounding environment; and an eye tracking system configured to determine vergence of the viewer's eyes, wherein the display system is configured to: determine a depth of the vergence of the viewer's eyes; cause the first variable focus lens element to modify a wavefront divergence of the projected light for forming the virtual object on a depth plane, wherein an amount of the modification of the wavefront divergence is based on the determined depth of the vergence of the viewer's eyes and on an amount to correct a refractive error of the viewer's first eye, and cause the second variable focus lens element to modify a wavefront divergence of incoming light from the object in the surrounding environment on a depth plane, wherein an amount of the modification of the wavefront divergence is based on the determined depth of the vergence of the viewer's eyes and on an amount to correct the refractive error of the viewer's first eye. determine a depth of the vergence of the viewer's eyes; cause the first variable focus lens element to modify a wavefront divergence of the projected light for forming the virtual object on a depth plane, wherein an amount of the modification of the wavefront divergence is based on the determined depth of the vergence of the viewer's eyes and on an amount to correct a refractive error of the viewer's first eye, and cause the second variable focus lens element to modify a wavefront divergence of incoming light from the object in the surrounding environment on a depth plane, wherein an amount of the modification of the wavefront divergence is based on the determined depth of the vergence of the viewer's eyes and on an amount to correct the refractive error of the viewer's first eye.