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Purkinje images have been a traditional source of information in studying the optics of the eye. A light source illuminating the eye generates specular reflections at the different ocular interfaces [...]

We evaluated the dynamics of ocular surface temperature using thermal imaging in 21 glaucoma subjects and 19 healthy subjects. On opening of the eye, subjects with glaucoma showed significantly cooler temperatures in the central cornea compared to the control group. The upper eyelid was also significantly cooler just before the eye opened. Immediately after opening the eye, the dynamic of temperature change was different in the two groups. In subjects with glaucoma, the eyes cooled significantly faster, with an average decrease of 0.49°C during the first second compared to 0.24°C in the control group. Our results support the hypothesis that both the stability of the tear film and changes in the ocular blood supply in subjects with glaucoma play an important role in thermal dynamics of the ocular surface.

We have designed an intraocular telescope for the posterior chamber of the human eye of patients with age related macular degeneration. The basic design is composed of two decentered high optical power lenses ( + 66D and −66D) inducing a 3° prismatic effect to project a magnified central field of view into a healthier location off the central fovea. Aspheric surfaces were used to ensure a compromise between good optical quality and high tolerance to the final axial position of both lenses after surgery. With this particular design, the telescope affords an extended range of depth of focus, high tolerance to different axial lengths of the eye and robustness against typical values of astigmatism and higher order aberrations. The final design has been manufactured in a foldable material and is compact enough to facilitate surgical implantation. This telescope is a simple but promising intraocular visual aid for AMD patients.

To investigate the effect of age on the contributions of the anterior cornea and internal components to ocular aberrations in the peripheral visual field.

To better understand how peripheral refraction affects development of myopia in humans, specialized instruments are fundamental for precise and rapid measurements of refraction over the visual field. We compare here two prototype instruments that measure in a few seconds the peripheral refraction in the eye with high angular resolution over a range of about ±45  deg. One instrument is based on the continuous recording of Hartmann–Shack (HS) images (HS scanner) and the other is based on the photorefraction (PR) principle (PR scanner). On average, good correlations were found between the refraction results provided by the two devices, although it varied across subjects. A detailed statistical analysis of the differences between both instruments was performed based on measurements in 35 young subjects. Both instruments have advantages and disadvantages. The HS scanner also provides the high-order aberration data, while the PR scanner is more compact and has a lower cost. Both instruments are current prototypes, and further optimization is possible to make them even more suitable tools for future visual optics and myopia research and also for different ophthalmic applications.

The mechanisms of compensation of aberration between cornea and lens are somehow modified during both accommodation and aging. In 15 individualized ocular models of young and unaccommodated eyes, we used morphological data of the lens to simulate the effect of accommodation and aging on these mechanisms. The predicted changes in aberrations were compared to data from the literature. In general, only the variation of the lens curvature was enough to reproduce the decrease in ocular spherical aberration (SA) during accommodation. However, the increase in SA with age could only be explained as a consequence of an increase in the conic constant of the lens and/or additional changes on the gradient index.

To compare the effects of “simulated” and “real” spherical and astigmatic defocus on visual acuity (VA).

On July 26–29, 2010 the 13th International Myopia Conference was held in Tübingen, Germany and included 17 separate symposia, each with 3–5 presentations. Here, in a single paper, the chairs of those Symposia describe the scientific advances noted at the conference and include the full abstracts of the individual myopia papers presented in each symposium along with the authors and their institutions. The 17 Symposia covered 7 topics: Why Study the Mechanisms of Myopia?; Novel Approaches to Risk Factors; Signaling Eye Growth- How Could Basic Biology Be Translated into Clinical Insights?; Where Are Genetic and Proteomic Approaches Leading?; How Does Visual Function Contribute to and Interact with Ametropia?; Does Eye Shape Matter?; Why Ametropia at All?

To study the variability of peripheral refraction in a population of 43 subjects with low foveal refractive errors.

We present a brief historical background and a description of the main features of the eye’s optical properties: the eye is a simple, but rather optimized, optical instrument. It is only since Galileo’s time that the importance of the eye as a part of different optical instruments has driven a continuous scientific exploration of ocular optics. In the past decade, the use of wavefront sensing technology allowed us to complete our understating of eye optics as a robust aplanatic system.

A new device was designed to provide fast measurements (4 s) of the peripheral refraction (90° central horizontal field). Almost-continuous traces are obtained with high angular resolution (0.4°) while the subject is fixating a central stimulus. Three-dimensional profiles can also be measured. The peripheral refractions in 10 emmetropic subjects were studied as a function of accommodation (200 cm, 50 cm, and 25 cm viewing distances). Peripheral refraction profiles were largely preserved during accommodation but were different in each individual. Apparently, the accommodating lens changes its focal length evenly over the central 90° of the visual field.

We studied the mechanism of compensation of aberrations within the young human eye by using experimental data and advanced ray-tracing modeling. Corneal and ocular aberrations along with the alignment properties (angle kappa, lens tilt, and decentration) were measured in eyes with different refractive errors. Predictions from individualized ray-tracing optical models were compared with the actual measurements. Ocular spherical aberration was, in general, smaller than corneal spherical aberration without relation to refractive error. However, horizontal coma compensation was found to be significantly larger for hyperopic eyes where angle kappa tended to also be larger. We propose a simple analytical model of the relationship between the corneal coma compensation effect with the field angle and corneal and crystalline shape factors. The actual shape factors corresponded approximately to the optimum shapes that automatically provide this coma compensation. We showed that the eye behaves as an aplanatic optical system, an optimized design solution rendering stable retinal image quality for different ocular geometries.

We present a new methodology to obtain, to the best of our knowledge, the first intraocular lens (IOL) designed to balance the coma induced by the cornea due to the global ocular tilt. This lens is designed to mimic the situation naturally occurring in the normal healthy eye. The new proposed IOL provides an improved optical quality for all lens powers.

The 9th European Meeting on Visual Physiological Optics (VPO2018) was held August 29–31, 2018, in Athens, Greece. This issue of the Journal of the Optical Society of America A (JOSA A) is a dedicated feature, including numerous articles that span a large range of visual optics related topics, ranging from geometrical optics to visual psychophysics and from optical metrology to ophthalmic diagnostic technologies. The next VPO meeting will be held August 2020 in Cambridge, UK.

A new intraocular lens has been developed to correct coma. Another finding about metamerism shows that the eye-brain connection stills surprises.