In this issue 69, we address the theme of eyewear lens personalization. Although the production of corrective lenses has always been based on a prescription for the necessary power and prisms, which is itself personalized for each of our two eyes, the possibilities of personalizing eyewear lenses have evolved massively over the past 10 years or more.

Lenses can be personalized to suit the position they will occupy in front of both eyes, thus giving additional freedom in the choice of frames and their adjustment to the customer’s face. Measurements of the precise position of the eyes in terms of the frames chosen and adjusted can therefore enable lens manufacturers to optimise compliance with the power and prism prescription for the corrective lenses mounted in the frames.

Research into the visual system as a whole, both static and dynamic, has resulted in the discovery of new and relevant personalization parameters to direct optimisation of corrective lens geometry. The visual cortex, associated with both eyes, interacts with our inner ear, our balance and then our posture, depending on the use we make of our vision.

Professor Emmanuel Alain Cabanis presents the importance of the N.O.P. (Neuro Ocular Plane) for the position of the head, depending on the direction of the gaze. This is a reference article on the biometrics of the visual system, which passes through the two centres of the eyeballs and is, to a certain extent, our visual gyroscope in all the static visual tasks that we perform.

Professor Mo Jalie reminds us of the key role played by the eyes’ centres of optical rotation in the optical engineering of corrective lenses. This article shows the importance of taking care with the parameters for mounting the lenses in their frames, and the adjustment of the frames on the customer’s face.

Control of the position of corrective lenses in terms of each of the centres of rotation of the eyes means better oculomotor comfort and maximised vision correction performance. A study in Denmark carried out by Dr Hans Bleshoy and comparing two types of lenses from the same family, one of which is calculated using actual rotation centre position measurements, shows the importance of this type of personalization.

It is also important to take account of the head’s posture, because people who move their head more than their eyes can generate a conflict of vision with the inner ear when
wearing progressive lenses. Guillaume Giraudet, researcher at the Montreal School of Optometry, tells us about the study carried out on the individual strength of eye/head coordination strategy (to read on www.pointsdevue.com) Bérangère Granger et al. sets out the recent discoveries made with the inter-individual study of the dynamic of eye vergence movements. This vergence and accommodation behaviour in transit mode translates the visual system’s ability to adapt to the object environment observed through corrective lenses.

Two other ensuing articles will be available to consult on our website. Also available on the website is a video interview with Professor Mo Jalie on personalized lenses in general.

Cécile Pétignaud sets out the main types of personalization parameters already well known and used by the various ophthalmic lens manufacturers, and Andy Hepworth takes us over the various stages in a customer’s visit to a sales outlet, underlining the importance of taking their personalized profile into account.

Coralie Barrau et al. presents the new Crizal Prevencia product which reduces the damaging and cumulative effects of harmful light (Blue-Violet and UV).

EDITORIAL N°69 by Jean-Pierre CHAUVEAU

SCIENTIFIC & MEDICAL

BEST PRACTICE

PRODUCT