Optics: eye examining – vision testing and correcting – Spectacles and eyeglasses – With antiglare or shading
Patent
1990-07-10
1994-06-14
Arnold, Bruce Y.
Optics: eye examining, vision testing and correcting
Spectacles and eyeglasses
With antiglare or shading
351 45, G02C 710
Patent
active
053214412
DESCRIPTION:
BRIEF SUMMARY
The invention relates primarily to sunglass lenses and in particular to such lenses which provide adequate screening from possibly damaging ultra-violet radiation without leaving the customary markings around the eyes which are normally associated with the wearing of sunglasses. However, it will be appreciated that the invention, in its broadest aspects, has other applications. Furthermore, there are many features disclosed in this specification which are themselves inventive both in relation to sunglass lenses and their production, and to other contexts.
As regards the primary aspect of this disclosure, it is known to provide sung. lass lenses with an ultra-violet blocker, such as a coating of benzophenone, to protect the eyes of a wearer from the possible harmful effects of ultra-violet radiation. However, such a blocker not only restricts the impingement of ultra-violet radiation on the sensitive parts of the eye but also restricts its impingement on other parts of the body shielded by the lens. In particular, the skin surrounding the eve will be shielded, since sunglass lenses are normally significantly larger than the body of the eye. As a result of this, the skin adjacent to the eye will be subject to less ultra-violet radiation than the remainder of the face. When the sunglasses are removed, and in some cases even when they are worn, there will be apparent an area of paler skin around the eye compared to regions of the face which are tanned. This is unsightly.
It has now been found that it is possible to obtain a satisfactory screening effect to protect the eye, by providing the ultra-violet blocker only in a central region of the lens, for example corresponding to the pupil of the eye. Of course, it might still be desired to provide blocker in the region radially outwards of this central region but to a lesser concentration, so as to provide some peripheral protection while still permitting a sufficient degree of tanning of the skin around the eye. Thus, viewed from one aspect there is disclosed herein a lens to protect the eye from harmful radiation which is provided with a light transmitting ultra-violet blocking agent, characterised in that the concentration of the blocking agent in a central region of the lens is greater than that in a peripheral region surrounding the central region.
Outside of the central region, there may be little or no blocking agent or alternatively blocking agent to a lower concentration insufficient to give full protection to the eye or to prevent adequate tanning of the skin. In the latter case, the concentration may increase in the radially inwardly direction, towards the central region. Within the central region the concentration may also vary, e.g. to be greatest at the centre. The boundary between the central region and the peripheral region may be abrupt, with a sudden change in concentration, or may be gradual. In the latter case there could be a generally constant gradient with the concentration increasing from the periphery to the centre, so that there would be no clearly defined boundary in terms of a change in concentration. In such a case, it may be necessary to consider the boundary as being a line at which the amount of blocker passes above a threshold value or there is a threshold value of effectiveness. The size of the central region may vary from e.g. 5 mm across to even 30 to 40 mm across, with an average for practical purposes being 10 or 15 mm. The larger size will provide protection for sensitive eye lids.
The shape of the central region can be circular, elliptical, polygonal, or of any other shape which will produce the desired effect of protecting the eye whilst permitting tanning in the surrounding area. It could be in the form of a narrow strip across the lens. The region does not necessarily have to correspond to the geometrical or optical centre of the lens.
Frequently, the blocker will be substantially colourless, and there may be provided other materials so as to tint the lens evently or with a gradient e.g. from top to bottom, provide polar
REFERENCES:
patent: 2043840 (1936-06-01), Singer
patent: 2286219 (1942-06-01), Martinek
patent: 3382183 (1968-05-01), Donoian
Arnold Bruce Y.
Dang Hung Xuan
Tanoptic AG
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