Opto-mechanical design of a dispersive artificial eye

Dynamic opto-mechanical eye model with peripheral refractions

Many myopia control methods based on the peripheral defocus theory have emerged towards applications in recent years. However, peripheral aberration is a critical issue, which is still not well-addressed. To validate the aberrometer for peripheral aberration measurement, a dynamic opto-mechanical eye model with a wide visual field is developed in this study. This model consists of a plano-convex lens representing cornea (f' = 30 mm), a double-convex lens representing crystalline lens (f' = 100 mm), and a spherical retinal screen with a radius of 12 mm. To optimize the quality of spot-field images from the Hartman-Shack sensor, the materials and surface topography for the retina are studied. The model has an adjustable retina to achieve Zernike 4th item (Z4 focus) ranging from -6.28 µm to +6.84 µm. As for mean sphere equivalent, it can achieve -10.52 D to +9.16 D at 0° visual field and -6.97 D to +5.88 D at 30° visual field with a pupil size of 3 mm. To realize a changing pupil size, a slot at the back of the cornea mount and a series of thin metal sheets with 2, 3, 4, and 6 mm holes are generated. Both on-axis aberrations and peripheral aberrations of the eye model are verified by a well-used aberrometer and the eye model to mimic a human eye in a peripheral aberration measurement system is illustrated.

Opto-Mechanical Eye Models, a Review on Human Vision Applications and Perspectives for Use in Industry

The purpose of this review is to aggregate technical information on existent optomechanical eye models (OME) described in the literature, for image quality assessment in different applications. Several physical eye models have been reviewed from peer-reviewed papers and patent applications. A typical eye model includes an artificial cornea, an intraocular lens or other lens to simulate the crystalline lens, an aperture as the pupil, and a posterior retinal surface, which may be connected to a light sensor. The interior of the eye model may be filled with a fluid to better emulate physiological conditions. The main focus of this review is the materials and physical characteristics used and the dimensional aspects of the main components including lenses, apertures, chambers, imaging sensors and filling medium. Various devices are described with their applications and technical details, which are systematically tabulated highlighting their main characteristics and applications. The models presented are detailed and discussed individually, and the features of different models are compared when applicable, highlighting strengths and limitations. In the end there is a brief discussion about the potential use of artificial eye models for industrial applications.

3D retinal imaging and measurement using light field technology

SIGNIFICANCE

Light-field fundus photography has the potential to be a new milestone in ophthalmology. Up-to-date publications show only unsatisfactory image quality, preventing the use of depth measurements. We show that good image quality and, consequently, reliable depth measurements are possible, and we investigate the current challenges of this novel technology.

AIM

We investigated whether light field (LF) imaging of the retina provides depth information, on which structures the depth is estimated, which illumination wavelength should be used, whether deeper layers are measurable, and what kinds of artifacts occur.

APPROACH

The technical setup, a mydriatic fundus camera with an LF imager, and depth estimation were validated by an eye model and in vivo measurements of three healthy subjects and three subjects with suspected glaucoma. Comparisons between subjects and the corresponding optical coherence tomography (OCT) measurements were used for verification of the depth estimation.

RESULTS

This LF setup allowed for three-dimensional one-shot imaging and depth estimation of the optic disc with green light. In addition, a linear relationship was found between the depth estimates of the OCT and those of the setup developed here. This result is supported by the eye model study. Deeper layers were not measurable.

CONCLUSIONS

If image artifacts can be handled, LF technology has the potential to help diagnose and monitor glaucoma risk at an early stage through a rapid, cost-effective one-shot technology.

Design of a near-eye display measurement system using an anthropomorphic vision imaging method

We developed a new near-eye display measurement system using anthropomorphic vision imaging to measure the key parameters of near-eye displays, including field-of-view (FOV), angular resolution, eye box, and virtual image depth. The characteristics of the human eye, such as pupil position, pupil size variation, accommodation function, and the high resolution of the fovea, are imitated by the proposed measurement system. A FOV scanning structure, together with a non-vignetting image-telecentric lens system, captures the virtual image from the near-eye display by imitating human eye function. As a proof-of-concept, a prototype device was used to obtain large-range, high-resolution measurements for key parameters of near-eye displays.

Nonpupil adaptive optics for visual simulation of a customized contact lens

We present a method for determining the deformable mirror profile to simulate the optical effect of a customized contact lens in the central visual field. Using nonpupil-conjugated adaptive optics allows a wider field simulation compared to traditional pupil-conjugated adaptive optics. For a given contact lens, the mirror shape can be derived analytically using Fermat's principle of the stationary optical path or numerically using optimization in ray-tracing programs. An example of an aspheric contact lens simulation is given to illustrate the method, and the effect of eye misalignment with respect to the deformable mirror position is investigated. The optimal deformable mirror conjugation position is found to be near the posterior corneal surface. Chromatic aberration analysis is also presented, and our findings indicate that the polychromatic simulation quality is similar to that of the monochromatic case, even though the mirror is a reflective component. The limitations of a single continuous surface deformable mirror to mimic a contact lens are outlined, with some recommendations for improving the quality of simulation.