Optics: eye examining – vision testing and correcting – Spectacles and eyeglasses – Ophthalmic lenses or blanks
Reexamination Certificate
2000-02-22
2002-04-02
Sugarman, Scott J. (Department: 2873)
Optics: eye examining, vision testing and correcting
Spectacles and eyeglasses
Ophthalmic lenses or blanks
C351S177000
Reexamination Certificate
active
06364483
ABSTRACT:
FIELD AND BACKGROUND OF THE INVENTION
The present invention relates to a multifocal lens capable of providing a wearer with a focused vision in a range of distances and of a method of utilizing same for treating an individual suffering from a visual disorder such as presbyopia. More particularly, the present invention relates to a simultaneous multifocal contact lens which employs overcorrection of a near vision additional correction of a peripheral near vision focal region to thereby provide a wearer with a complete range of focused vision, in particular focused near vision.
As an individual advances in years, typically past 40-45, a physiologic loss of accommodation in the eyes begins. This physiological loss, which is termed presbyopia, is characterized by an inability to focus on objects that are relatively near to the individual (typically less then 22 cm). In addition to aging, a variety of eye disorders, such as, for example, cataract, which often necessitates lens replacement, can also abolish an individual's ability to focus throughout a range of distances.
To correct the loss of a vision range, individuals rely upon spectacles, contact lenses or ophthalmic lens (in the case of lens replacement) having a number of different regions with different optical powers in order to find the appropriate optical power for the object or objects upon which the observer wishes to focus.
With spectacles, the process involves shifting the field of vision from typically an upper lens portion far power to a lower lens portion near power. With contact lenses, however, this approach has been less than satisfactory.
The prior art teaches two types of contact lens designs for the correction of presbyopia, alternating (or translating) and simultaneous.
The design of alternating (or translating) lenses is very similar to bifocal eyeglass lenses in that the wearer sees through the distance segment in the upper portion of the lens when looking straight ahead and sees through a lower near vision segment when the eye is moved to look down. The translation from distance to near in these lenses is achieved through the mechanical action of the lens resting on the lower eyelid and, when the eye looks down, the lens remains stable on the lower eyelid causing the pupil of the eye to translate from the distant vision portion of the lens to the near vision portion of the lens. As such, when fabricated from soft materials, numerous operational problems plagued these lenses which have, therefore, enjoyed very limited commercial success.
The design of simultaneous vision bifocal or multifocal contact lenses is either concentric or aspheric with focal power changing through different areas of the lens. These lenses are fitted so that distance, intermediate and near zones focus images simultaneously on the retina of the eye and the brain then separates out the image desired.
Theoretically, with adaptation, the ability to change focus naturally from near to far with no blurring in between can be achieved with simultaneous vision lenses.
As alternating presbyopic designs proved to be unsuccessful in soft contact lens designs, most of the development work with soft contact lenses was done in the area of simultaneous presbyopic correction with concentric designs or aspheric designs. Numerous examples of simultaneous bifocal contact lenses or ophthalmic lens exist in the art.
For example, U.S. Pat. No. 4,923,296 to Erickson describes a lens system which comprises a pair of contact lenses, each having equal areas of near and distant optical power, with the lens for one eye having a near upper half and a distant lower half and the lens for the other eye having a distant upper half and near lower half. Together they provide at least partial clear images in both eyes, and through suppression by the brain of the blurred images, allow alignment of the clear images to produce an in-focus image.
U.S. Pat. No. 4,890,913 to de Carle describes a bifocal contact lens comprising a number of annular zones having different optical powers. The object in the design of this lens is to maintain, at all times, regardless of pupil diameter, an approximately equal division between near and distant powers, which requires between six and twelve total zones on the lens.
Another attempt at providing a bifocal contact lens is described in U.S. Pat. No. 4,704,016 to de Carle. Again, this lens attempts to maintain, at all times, regardless of pupil diameter, an approximately equal division between near and distant powers.
Yet another attempt at providing a bifocal contact lens is described in U.S. Pat. No. 5,929,969. This lens comprises a number of circular ring zones of two optical powers.
Although the above described bifocal lenses provide some vision correction, a mismatching of the various optical zones may lead to destructive interference and thus a less than optimal vision in some instances.
In addition to bi-focal lenses, a number of multifocal lenses which attempt to improve upon their bifocal counterparts have also been described.
For example, U.S. Pat. No. 5,448,312 describes a multifocal concentric ophthalmic lens for presbyopic patients constructed with three general annular lens portions in a multifocal design. A central circular portion of the lens has only the patient's distance corrective power, and is surrounded by a first inner annular portion, which can consist of multiple annular rings having an inner radial portion which enhances the patient's near focal power encircled by radial portions of substantially equal cumulative amounts of distance and near optical power focal correction for the patient. This is surrounded by a second outer annular portion, which can also consist of one or more annular rings having additional distance focal power near the periphery of the optical surface area of the ophthalmic lens. Each annular ring has either a near or distance optical power and works in combination with other lens portions to yield the desired focal ratio in that portion of the lens.
U.S. Pat. No. 5,682,223 describes a multifocal lens design with near, far and intermediate optical power zones. The borders of these zones are optimized for pupil size as a function of lighting conditions.
In this design, zone placement and zone radii are not carefully planed and as such destructive interference cannot be avoided.
To overcome interference problems, U.S. Pat. No. 5,982,543 describes a multi refractive zone lens optimized with consideration for phase match between the zones.
However, the lens design described features lens coherence properties in visible light which vary considerably from one scene to the next.
Although some of the above described lenses have traversed some of the limitations inherent to multifocal lenses, these lenses still provide sub-optimal vision correction for some or all vision ranges.
The above described prior art designs, be it aspheric or concentric, cannot provide monocular multifocal correction for moderate to mature presbyopia. In most cases, some form of modified monovision is required in an attempt to satisfy the visual requirement for near and far vision.
To address this and other problems typical of prior art simultaneous multifocal lenses a variety of lenses with under or over corrected focal regions have been described.
For example, U.S. Pat. Nos. 5,864,378 and 5,864,379 describe a contact lens and an opthalmic lens (respectively) in which a central near vision zone ('379), or both a central near vision zone and a peripheral far vision zone ('378) are overcorrected. According to these patents, while such a correction does not impair distance vision, it compensates for presbyopia and therefore allows a user to focus on objects within a range of near and intermediate distances.
U.S. Pat. Nos. 5,919,229 and 5,702,440 both describe contact lenses with undercorrected peripheral near vision zones.
Although these lenses substantially enhance the focus range of an individual as compared to other prior art designs, such lenses still suffer from limitations which arise from the n
Golub Michael
Grossinger Israel
Friedman Mark M.
Holo OR Ltd.
Sugarman Scott J.
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