Adjustable adaptive compact fluidic phoropter with no mechanical translation of lenses

Abstract

We demonstrate a compact optical phoroptor consisting of adjustable astigmatic and defocus lenses. The lenses are fluidically controlled and allow for an arbitrary refractive error to be corrected without mechanically moving lenses. Shack-Hartmann measurements were used to characterize the optical properties of the individual lenses. The lenses were then assembled into the phoropter and controlled with three separate fluid controls. The phoroptor was verified by correcting the vision of a model eye with an induced refraction error.Ophthalmologists and optometrists commonly use a phoropter to determine refractive error in patients. The process typically involves subjective feedback from the patient using a repetitive verbal cue when ophthalmic trial lenses are mechanically switched in and out to change the refraction. The process relies on subjective feedback from the patient but is effective in determining a suitable prescription. However, this process is time consuming for both the patient and the examiner. Incorporation of fluidic lenses into the phoropter will allow a continuously varying optical wavefront that results in reduction of the time required for the examination, since the process could be computer controlled. The physical size and complexity of the standard phoropter is problematic from a manufacturing and deployment perspective, and the development of a fluidic lens system offers the potential to simplify and greatly reduce the size of the instrument. The phoropter monocle that was developed in this study measures 13.7 mm thick and 44.5 mm in diameter (Fig. 1). A pair of these phoroptor monocles could be head mounted to allow the patient to move his or her head during an examination, allowing the patient to receive a better sense of the amount of visual improvement under natural conditions. Fluidic lenses that are based on a flexible membrane use fluidic pressure to control the curvature of the flexible membrane. This control allows alteration of the optical wavefront in a continuous and consistent manner. Fluidic lenses have been used to circumvent the need to mechanically move a lens to provide optical zoom [1][2][3]. Similarly, we have capitalized on recent demonstrations of fluidic lenses capable of defocus (−20D to 20D) and astigmatic (0 to 8D) correction [4,5] to construct a phoropter without the need to mechanically introduce lenses into the view of the patient. The fluidic lenses have low values of higher-order Zernike terms, as demonstrated by their high visual quality with a visual Strehl ratio computed in the frequency domain of greater than 0.75 for the defocus lens and greater than 0.98 for the astigmatic lens [5]. A phoropter was constructed using two astigmatic lenses oriented at 45° to each other and combined with a defocus lens, which allows for continuous spherical and cylindrical correction. To the best of our knowledge, this is the first demonstration of a phoropter based on fluidic lenses.The phoropter is composed of one defocus lens and two astigmatic fluidic lenses t...

Elastomeric lenses with tunable astigmatism

“…Elastomeric lenses thus differ significantly from pressure-actuated membrane lenses, since the latter will need at least three membranes to tune, for example, focal length and astigmatism. 6 Furthermore, elastomeric lenses benefit from a well-defined optical surface even in the unstrained state, in contrast to liquid lenses, where the surface is shaped by an equilibrium of surface tension and gravity, and membrane-type lenses, where the membrane must be significantly distended to achieve short focal lengths. Finally, gravitational sagging (introducing coma as a dominant wavefront error), which is an issue for many membrane lenses, does not occur with these bulk elastomeric lenses.…”

“…A more versatile approach with a combination of several membrane lenses was pursued by Marks et al 6 Here two perpendicularly oriented cylindrical lenses provide variable astigmatism, whose total focus is compensated with a rotational symmetric membrane lens.…”

Eye Vision Testing System and Eyewear Using Micromachines

“…These recent E-lens device technologies and adaptive optic system advances can be incorporated in the proposed eye vision system using micromachines to enable user scenario-dependent optimal performance. also been proposed for phoropters in a patent by Quaglia in 1995 [27] and later in 2010 by the group of Peyghambarian [28]. In 1996, an LC diffractive-optic E-Lens had been designed [29] and in 2006, the Peyghambarian group suggested the use of the LC diffractive-optic E-Lens for eye exams to measure eye refractive power change [30].…”

Eye vision system using programmable micro-optics and micro-electronics

“…Starting in the mid-1980s, the General Electric Corporate Research & Development Center (GE-CRD) fabricated novel electronically controlled Liquid Crystal (LC) lens devices, including for eye correction measurement applications [6][7][8]. Use of liquid-based lenses using mechanical pressure to change lens focal length has also been proposed for phoropters in 1995 and also more recently [9][10]. In addition, apart from using an electronic LC lens in a phoropter to get new eyewear refractive readings [7], two dimensional (2-D) optical spatial light modulator devices (via LC and micromachined or MEMS) devices have be proposed for color blindness tests as well as to provide the capability to perform eye strain relief and eye muscle exercises [11].…”