Some history: Critical dates and transitions

In the late 1990’s an idea was born in the minds of three individuals. Pierre Simonet (UdeM), Marc Alexandre and Laurent Vacherot (Essilor) contemplated the creation of a University-Industry partnership in the domain of vision sciences and ophthalmic optics. This idea was to become the Essilor Industrial Research Chair. After considering a number of valuable candidates and options, the Chair was finally officially created in 2001 and offered to. Given my expertise in human psychophysics, perception and performance, it was mutually decided that the Chair would focus on the impact of visual geometrical distortions on human function. In 2003 the Essilor Industrial Chair officially became the NSERC-Essilor industrial Chair, which doubled the research funds available for the work. In parallel, I was fortunate enough to obtain major infrastructure funds from the Canadian Foundation for Innovation (CFI) and other partnering sources that dramatically increased the research possibilities of the laboratory. We were off… The Chair was officially inaugurated in 2004 (see pictures) with an event in Montreal where many dignitaries and representatives of the partners participated.

A mutually beneficial enterprise

This partnership has proven fruitful from many perspectives. From the University perspective, it has attracted numerous undergraduate, graduate, and postdoctoral students along with other research staff and highly qualified personnel. This team of researchers has contributed to a large production of scientific articles, industrial white sheets, and intellectual property documents over the years. It has also provided with an alternative research experience for the personnel by emphasized the applicability of what are often considered fundamental issues in vision science.

The impact on the industry was also critical. It supplied the industrial partner with accessibility to an important knowledge base along with top of the line research facilities. This permitted to address and elucidate some fundamental properties of the visual system that are critical for successful ophthalmic lens design.

Fig. 1: Left to right: Jacques Gresset, Director of the School of Optometry, Robert Forget, Director of the Interdisciplinary Readaptation Research Centre, Bernard Maintenaz, Inventor of Varilux, Michel Lespérance, Secretary of Montreal University, Jocelyn Faubert, Holder of the Industrial Research Chair at the CRSNG-Essilor, Consultant in Natural Sciences
Research and Engineering, School of Optometry, Montreal University, Nigel Lloyd, VP CRSNG, Consultant in Natural Sciences Research and Engineering, School of Optometry,
Robert Lacroix, Rector of Montreal University, Carmen Charette, President of the Canadian Foundation for Innovation, Laurent Vacherot Chief Operating Officer, Essilor, Jean-Luc
Chuppiser, Research & Development Director, Essilor, Philippe Alfroid, Administrator.

Introducing virtual reality

One of the very innovative contributions of the NSERC-Essilor research Chair was the introduction of immersive virtual reality environments to study human behaviour.

The use of such immersive environments for scientific research on human behaviour was less than obvious at the time. After all, controlling for good luminance and colour, real-time integration of multiple stereoscopic surfaces and simultaneous motion capture without having an impact on the measurements due to phase delays or other integrative notions was quite a feat to achieve with the technologies available at the time. Nonetheless, we were able to resolve these issues and develop a very productive research and development program.

The focus was primarily using the power of these environments to understand how dynamic visual scenes influence our behaviours, even for the simplest of conditions such as maintaining a stable posture control. We can summarize the breadth of the work done over the years in a few broad categories:

1) Aging and maturation of the visual-perceptual process

2) Dynamic visual perturbations on balance control

3) Visual exploration strategies such as eye-head strategies

4) Perceptual-cognitive processing of dynamic visual scenes

5) Multisensory integration

1) Aging and maturation of the visual-perceptual process:

In a serie of studies we have looked at the effect of aging on a number of perceptual processes [3]. For instance we have characterized the impact of aging on the capacity to process low-level visual information such as luminance and colour [8, 17, 25] and mid-level perceptual information such as the perception of symmetrical images [15], texture [8, 16], stereoscopy [18], curvature [19] and mid to high level perceptual capacities such as face perception [1] and biological motion perception [20]. These studies have provided us with a breath of knowledge on how the aging process impacts perceptual processes and are generally consistent with a theory of aging that implies that functional deficits due to aging are proportional to the amount of neural machinery required to process the image or visual scene [3]. This fundamental knowledge guides us in determining what kind of visual information will be more difficult to process as a function of aging and therefore help us understand what kind of ophthalmic lens induced visual distortions will be problematic for different age populations.

2) Dynamic visual perturbations on balance control

Another serie of studies examined the impact of dynamic visual perturbations, such as large optic flow field movements, on balance control as it can be predicted by dynamic distortions generated from ophthalmic lenses that the visual system will be confronted with such transitions when wearing glasses [2, 4]. The full-immersive virtual environment provided by the CAVE environments is perfectly suited for that [9]. We were, therefore, able to conduct research projects that addressed important issues such as the visual field origin of the perturbation on balance control [26]. This is important as distortions from lenses dramatically depend of the visual field position and it is obviously paramount to determine the extent of this on critical behaviours such as posture control. We were further curious as to the impact of visual perturbations through the maturation process [12]. We showed that the visual dependence of postural control changes dramatically as a function of age. Other studies looked at the effect of other types of visual stimuli such as sway on posture control and motion sickness [7]. Recently, we also looked at the impact of cognitive load combined with visual perturbations on posture control as a function of aging again showing different patterns of responses as a function of age of the observers [14].

Fig. 2: Images of CAVE.

3) Visual exploration strategies such as eye-head strategies

Another area of concern to ophthalmic lenses producers is how we explore the world. In particular the notion of eye-head movements are of importance given that how we move the eyes and head will dramatically impact the dynamics of visual stimulation [2, 4]. Consequently, Essilor has developed an entire line of individually based lens designs called Ipseo. As a logical extension of this process the Chair has explored issues related to eye-head measures. We have examined the robustness of the measure as a function of strong visual backgrounds such as optic flow [6]. This allowed us to determine the relative robustness of the eye-head coefficient used for the Ipseo lens design under more ecological conditions.

4) Perceptual-cognitive processing of dynamic visual scenes

Another area of concern for the research Chair was how individuals process complex dynamic visual scenes. The capacity to move about in a dense crowd is quite complicated because individuals are confronted with sudden changes in direction ad complex dynamics where objects disappear and reappear while you have to attend to multiple elements. In the concern of developing ecological environments for the study of human behaviour in response to ophthalmic distortions, it was critical that we understand these dynamics under ecological conditions. For this purpose we have designed a large 3-dimensional virtual environment and designed a new multiple object tracking task that we call 3D-MOT. We have studied this for a number of conditions and populations [10, 13, 27]. We have shown that the binocular input was critical for this capacity as measured by speed thresholds and that this process is highly trainable in older observers [10] and high-level athletes [11]. Therefore, how well observers can process complex dynamic scenes in the real world (such as dense crowd dynamics or sports activities) will critically depend on the age of the observer but also on the training of the observer giving us hope as to the reversibility of the age factor.

5) Multisensory integration

Another factor that was considered at length in the NSERC-Essilor industrial research Chair is that visual information is never or rarely processed isolated from other sensory stimulation. For instance, a visual stimulus is often accompanied by a sound or by a touch when at proximity. If someone calls out my name while within my visual field, my search strategy will depend not only on visual information but also on sound processing. In order to achieve a good understanding on how we explore and process visual scenes we must therefore understand how these multiple senses interact. We have conducted a series of studies on how the entry of one sense (facilitating stimulus) can influence the detectability of the other. This has lead to a general model we call “fulcrum” meaning that which facilitates action [21, 22, 24]. The general outcome of this research has lead to the knowledge of when the individual is in the best “detectability” condition for a given stimulus property when in the presence of another sensory input. For instance we have shown that we can improve visual contrast sensitivity when simultaneously presenting particular auditory sounds or tactile stimulations. Towards Individual design

Where are we going now and what is the future for the NSERC-Essilor Chair? There has been a major revolution in the last decade in regards to lens technology. Lens surfacing technology is now capable of cutting any possible shape in both the front and back surfaces of the lens. This translates into limitless possibilities of lens design. How are we going to make full use of such technology? The only way we can use the full potential is to better understand the individual characteristics of the lens wearers. For this reason, the NSERC-Essilor Chair has changed its focus from a general population model to an individual response approach in an attempt to optimize the designs for each wearer and make full use of the new technologies available. To achieve this goal we are now exploring the domains mentioned above but from a individual perspective. For instance individual differences in postural stability as a function of transient changes is being studied. Also characterizing responses in perceptual-cognitive processing of dynamic scenes and multisensory processing capacities are all being studied as we speak. We are expecting concreted evaluation protocols that will help the lens designers make decisions of high relevance for each individual lens wearer.

In conclusion, I would like to iterate that NSERC, Essilor and University of Montreal have been wonderful partners and have permitted us to lay the foundations upon which the new generation of lens design will rely.

Ref. [5, 23]