Optics: eye examining – vision testing and correcting – Spectacles and eyeglasses – Ophthalmic lenses or blanks
Reexamination Certificate
1999-12-01
2001-05-01
Epps, Georgia (Department: 2873)
Optics: eye examining, vision testing and correcting
Spectacles and eyeglasses
Ophthalmic lenses or blanks
C623S006170, C623S006280
Reexamination Certificate
active
06224210
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention concerns multifocal artificial ocular lenses, by which is meant both rigid material artificial ocular lenses and flexible material artificial ocular lenses.
In the present context the expression artificial ocular lenses means contact lenses, intra-ocular implants or intracorneal lenses.
2. Description of the Prior Art
Multifocal contact lenses have at least two corrective areas, namely a near vision area adapted to correct near vision and a distance vision area adapted to correct distance vision.
One such multifocal contact lens has two concentric corrective areas, for example, disposed so that the near vision area is at the center of the lens and the distance vision area is at its periphery, in which case the lens is usually called a “central NV” lens.
Alternatively, the distance vision area is at the center and the near vision area is at the periphery, in which case the lens is usually called a “central DV” lens.
The vision performance of most multifocal contact lenses of this type is strongly dependent on the pupil diameter of the user.
The pupil of the eye exhibits a natural reflex reaction to two types of stimulation: its diameter decreases as the distance between it and the observed object is reduced and/or when the luminance of that object increases.
Variations in the pupil diameter related to the distance of the object can be exploited by appropriate multifocal optics, and in practise they are operative in the appropriate sense with central NV lenses.
With these lenses, the constriction of the pupil that accompanies near vision automatically leads to at least partial selection of the appropriate corrective area, and the same goes for the dilation of the pupil that accompanies distance vision.
In both cases the result of the reaction of the pupil to the observation distance is an improvement in the contrast in the image obtained on the retina.
On the other hand, the variations in the pupil diameter associated with the luminance of the observed object, and therefore in practise with its illumination, have undesirable effects.
With a central NV lens, for example, strong illumination results in constriction of the pupil which, by the resulting selection of the effective corrective area, favors near vision correction to the detriment of distance vision correction, even if the observed object is at a great distance.
Similarly, with a central DV lens strong illumination favors the correction of near vision to the detriment of distance vision even if the observed object is at a short distance, as may be the case for reading in a well lit place, for example.
In both cases the change from low luminance to high luminance is therefore prejudicial to the stability of visual performance, or more generally to the quality of optical performance, to the detriment of the visual comfort of the user.
A general object of the present invention is an arrangement that minimizes, if not eliminates, this drawback.
SUMMARY OF THE INVENTION
To be more precise, the present invention consists in a multifocal artificial ocular lens having at least two corrective areas, namely a near vision area adapted to correct near vision and a distance vision area adapted to correct distance vision, wherein the transparency of said lens varies in inverse proportion to its illumination.
In practise the above multifocal artificial ocular lens is made from a material having a transparency which decreases as its illumination increases.
It is a polymer or a copolymer incorporating a photochromic substance, for example.
By acting on the transparency, and therefore on the light transmission coefficient, the photochromic substance employed limits the effect of the variations in luminance or, to be more precise, it limits, if not eliminates, the reflex constriction of the pupil occasioned by high luminance.
The advantages for the user are improved visual comfort and enhanced safety.
As demonstrated by trials, an 80% variation in the light transmission coefficient between low illumination and high illumination is in practise more than sufficient to achieve the required effect.
Incorporating a photochromic substance into the material from which an eyeglass lens is made, and even into that of a contact lens, is already known in itself, of course.
However, until now, the only effect looked for has been effective and practical protection of the eye against glare.
In the case of a multifocal artificial ocular lens, the invention advantageously adds an improvement in optical performance to the above protection.
The features and advantages of the invention will emerge from the following description given by way of example with reference to the accompanying diagrammatic drawings.
REFERENCES:
patent: Re. 33477 (1990-12-01), Loshaek
patent: 3507552 (1970-04-01), Scott
patent: 3950082 (1976-04-01), Volk
patent: 4304895 (1981-12-01), Loshaek
patent: 4636049 (1987-01-01), Blaker
patent: 4681412 (1987-07-01), Lemelson
patent: 4851471 (1989-07-01), Maltman
patent: 4869587 (1989-09-01), Breger
patent: 4913544 (1990-04-01), Rickwood
patent: 5108427 (1992-04-01), Majercik
patent: 5260727 (1993-11-01), Oksman et al.
patent: 5757459 (1998-05-01), Bhalakia et al.
patent: 0 227 337 (1987-07-01), None
patent: 0 245 020 (1997-11-01), None
patent: WO 86/01996 (1986-04-01), None
patent: WO 95/08135 (1995-03-01), None
Baude Dominique
Chateau Nicolas
Grollier Corinne
Epps Georgia
Essilor International (Compagnie Generale d'Optique)
Schwartz Jordan M.
Young & Thompson
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