BACKGROUND OF THE INVENTION The natural crystalline lens has two main functions, namely, to focus the image of a distant object on the retina, and to change its refractive power to focus the image of a near object over the retina, this being referred to as accommodation.

The accommodative system comprises several elements including the ciliary body and muscles, the zonular apparatus and the crystalline lens.

Lack of accommodation is a natural aging process of the accommodative system (presbyopia) or may occur as a result of damage to any of the components of the accommodative system, such as or acquired or congenital disease, ocular trauma or following cataract surgery.

In cataract surgery the opaque crystalline lens is removed and replaced by an artificial intraocular lens (IOL), which is preferably placed in the location of the natural lens, i. e., within the remaining capsular bag. The optical element (optic) is generally held within the bag by the supporting element (haptic). The thick natural lens is usually replaced by a much thinner IOL; therefore, the capsular bag is flattened and stretched laterally by the haptic. The capsular equator is typically placed behind the ciliary processes and the ciliary-zonular-lens complex loses its ability to change the refractive power of the ocular system. Loss of accommodation generally characterizes implantation of conventional artificial IOLs, and the optical power of the eye following IOL implantation is fixed and stable.

SUMMARY OF THE INVENTION In an embodiment of the present invention an intraocular element may be placed in front of the lens. The lens, either the crystalline or an artificial IOL, may provide a fixed focus on a distant object. The implanted element, activated by components of the natural accommodative system, may act as an optical addition to provide focus on near objects.

The accommodative system is activated by contraction of the ciliary muscle, which acts on the zonular apparatus. The resultant change in tension of the lens surface may be accompanied by a change in the curvature of the anterior, and to a less extent of the posterior, surfaces of the lens and hence changes its refractive power. Aging processes, trauma or surgery may affect the function of the zonules and the lens capsule, and the flexible organs may loose their elasticity. However, the aged ciliary muscle may still function, even though its activation is not followed by a change in the refractive power of the eye.

The intraocular element of the present invention is designed to utilize the ability of the ciliary muscle, or any element of the natural accommodative system, to function. Since a conventional intraocular lens situated within the capsular bag is positioned behind the ciliary body, contraction of the ciliary muscle mainly occurs in front of the IOL. The accommodative element implanted in front of the IOL may utilize the change in position or volume of the ciliary body to create a change in an optical characteristic of the implant, <BR> <BR> e. g. , the refractive power of the implant. Similarly, an element implanted in front of the crystalline lens may be activated by the ciliary muscle to provide additional refractive power to the presbyopic natural lens.

The change in refractive power required, for example for reading, is 2.5-4. 0 diopters (focus on objects at 25-40 cm). Since the"base"lens, either the natural lens or an IOL, focuses at distance and has a fixed refractive power, the implanted element of the <BR> <BR> invention is universal to all eyes and all IOLs. Eyes with ametropia, i. e. , myopia (short- sightedness) or hyperopia (far-sightedness), or eyes with astigmatism may require distance correction (glasses) for clear distance vision. The intraocular element of the present invention enables near focus while using the distance correction.

The implanted optical element may change its dioptric power in various ways, for example, by the anterior-posterior movement of a fixed power lens, acting as a telescopic system. This movement may be transferred by solid, semi-liquid or liquid material.

Alternatively, pressure or tension on the implant may change the anterior and/or posterior curvature of the lens, thus increasing its refractive power. As another alternative, pressure or tension over the implant may change its physical or chemical properties, for example, change the index of refraction of its optical element.

BRIEF DESCRIPTION OF DRAWINGS The present invention will be further understood and appreciated from the following detailed description taken in conjunction with the drawing in which: Fig. 1 is a simplified sectional illustration of an accommodative intraocular element, constructed and operative in accordance with an embodiment of the invention, wherein contraction of the ciliary muscle may move a central optical element forward; Fig. 2 is a simplified sectional illustration of an accommodative intraocular element, constructed and operative in accordance with another embodiment of the invention, wherein central movement of the periphery of the intraocular element may change the curvature of the central optical element, thus increasing its optical power; Fig. 3 is a simplified sectional illustration of an accommodative intraocular element, constructed and operative in accordance with still another embodiment of the invention, comprising a balloon whose optic power may be changed by contraction of the ciliary muscle; and Fig. 4 is a simplified sectional illustration of an accommodative intraocular element, constructed and operative in accordance with yet another embodiment of the invention, wherein central movement of the periphery of the intraocular element may increase the optical power of a central optical element.

DETAILED DESCRIPTION OF THE INVENTION Reference is now made to Fig. 1, which illustrates an accommodative additive intraocular element 10, constructed and operative in accordance with an embodiment of the invention. Fig. 1 shows an intraocular lens (IOL) 12 implanted in the capsular bag 14.

An IOL haptic 16 is located behind (posterior to) the ciliary processes 18 and the zonules 20 are relaxed (e. g. , along the loop axis). The main bulk of the ciliary processes 18 (ciliary body or the ciliary muscle) is located anterior to the IOL 12. Fig. 1 also illustrates other structures of the eye, such as the iris 22 and the cornea 24.

Intraocular element 10 may be implanted in front of IOL 12 and behind the iris 22, outside of capsular bag 14. Intraocular element 10 may comprise a periphery 26 adapted to be held at accommodating structure of the eye, e. g. , the ciliary processes 18. Intraocular<BR> element 10 may further comprise a central optical element 28, e. g. , a lens, attached to periphery 26. Optical element 28 may form a combined lens complex together with IOL 12. Periphery 26 may be formed with a kink or bend 30. Contraction of the ciliary processes 18 (ciliary muscle) may push the periphery 26 of the intraocular element 10 centrally (i. e. , radially inwards), as indicated by arrows 32, and central optical element 28 may move forward, as indicated by arrow 34, to the position indicated by dotted lines 36, thus changing the focus of the combined lens complex. It is noted that intraocular element 10 may provide the same functionality with the natural lens of the eye as well, instead of IOL 12.

Accommodative additive intraocular element 10 may be implanted in the eye at the same time of implantation of IOL 12, or may be implanted into an eye with an existing IOL.

Reference is now made to Fig. 2, which illustrates an accommodative additive intraocular element 40, constructed and operative in accordance with another embodiment of the invention. Intraocular element 40 may be constructed similarly to intraocular element 10, and like elements are indicated by like numerals. The central optical element 28 of intraocular element 40 is sufficiently flexible such that its curvature is changeable.

In this embodiment, the central movement of the periphery 26 of the intraocular element 40 may change the curvature of the central optical element 28, thus increasing its optical power.

Reference is now made to Fig. 3, which illustrates an accommodative additive intraocular element 50, constructed and operative in accordance with still another embodiment of the invention. Intraocular element 50 may comprise a balloon 52 filled with liquid and/or semi-liquid material 54, such as water or gel. A central portion of balloon 52 may comprise a central optical element 56. The pressure on the periphery of balloon 52, generated by contraction of the ciliary muscle, may cause bulging of central optical element 56, thereby increasing the curvature of central optical element 56 and its optical power. Central optical element 56 may form a combined lens complex with lens 12. The contraction of the ciliary muscle may move forward and change the focal point of the combined lens complex, as described hereinabove for the embodiment of Fig. 1.

Alternatively or additionally, the change in pressure within balloon 52 may change the physical-chemical qualities of central optical element 56, for example by changing the index of refraction.

Reference is now made to Fig. 4, which illustrates an accommodative additive intraocular element 60, constructed and operative in accordance with yet another embodiment of the invention. Intraocular element 60 may comprise a periphery 62 adapted to be held at accommodating structure of the eye, e. g. , the ciliary processes 18.

Intraocular element 60 may further comprise a central optical element 64 attached to periphery 62. Central optical element 64 may comprise a flexible, balloon-like structure capable of contraction and expansion. Central optical element 64 may alternatively be filled with liquid and/or semi-liquid material, as described for the embodiment of Fig. 3.

Contraction of the ciliary muscle may urge the periphery 62 of the intraocular element 60 towards the center. This may create pressure on central optical element 64, causing an increase in the curvature of its anterior and posterior surfaces. Alternatively, the movement towards the center may relax the lateral tension of the periphery or fibers connected to the optical element 64, thus allowing the optical element 64 to expand in the anterior-posterior axis by its own elastic properties (similar to the accommodative process of the natural crystalline lens).

Reference is now made to Fig. 5, which illustrates an accommodative additive intraocular element 65, constructed and operative in accordance with yet another embodiment of the invention. Intraocular element 65 may comprise two or more optical elements 66, each adapted to be held at the accommodating structure of the eye, e. g. , the ciliary processes 18. Optical elements 66 may comprise without limitation, optical prisms, Fresnel lenses, holographic lenses and the like, whose optical power may be changed upon relative movement between the optical elements 66, e. g. , sliding over each other (indicated by arrow 67) or by rotational motion.

The embodiments described hereinabove may be triggered or activated by components of the natural accommodating system of the eye, e. g. , the ciliary processes 18.

In accordance with another embodiment of the invention, any of the embodiments of the invention may be triggered, excited, stimulated or activated by an external stimulus. For example, as shown in Fig. 6, an accommodative additive intraocular element 68 may comprise an actuator 74, which may be triggered or activated by an external stimulus 70.

(Accommodative additive intraocular element 68 may be constructed like any of the <BR> <BR> embodiments of the invention. ) For example, actuator 74 may comprise a miniature lever, spring-arm, pump, solenoid or electromagnet or any other element that may cause accommodating action by any of the accommodative additive intraocular elements of the invention. (For example, actuator 74 may cause contraction of the balloon-like central optical element 64 or may push the periphery 26 of the intraocular element 10 centrally).

The external stimulus 70 may comprise a remote control device of any size or shape, planted in or on the human body or a separate unit external to the body. External stimulus 70 may be in wireless or wired communication with actuator 74. External stimulus 70 and actuator 74 may be electrical, mechanical, hydraulic, pneumatic or a combination thereof, and may include a power source mounted anywhere (not shown).

External stimulus 70 may operate voluntarily. For example, external stimulus 70 may comprise a remote control, which the user presses to activate actuator 74 in order to operate the accommodative additive intraocular element and effect accommodation of the eye.

Alternatively, external stimulus 70 may operate non-voluntarily. For example, external stimulus 70 may cooperate with a biofeedback sensor 72, which may be adapted to sense a biological phenomenon associated with the ciliary processes or other portions of the eye. For example, if a person's natural accommodating system is not sufficiently strong to cause accommodation of the lens (as may be the case with elderly patients), biofeedback sensor 72 may nevertheless sense ocular nerve and/or muscle signals associated with the weakened accommodating system. Upon detection of such signals, sensor 72 may signal external stimulus 70 to activate actuator 74 to operate the accommodative additive intraocular element 68 and achieve the required accommodation of the lens.

As another alternative, instead of the ciliary processes 18 applying direct force to move the accommodating additive element, as in the embodiments of Figs. 1-5, in the embodiment of Fig. 6 the ciliary processes 18 may serve as the external stimulus 70 (or control mechanism) to activate actuator 74 the accommodating element. The ciliary processes 18 may actuate actuator 74, for example, by means of direct pressure on the actuator or in conjunction with sensor 72.

In contrast to the embodiments of Figs. 1-5, the accommodating additive element 68 in the embodiment of Fig. 6 does not necessarily have to be connected to the ciliary body or processes at all. Rather, the accommodating additive element 68 may be connected to any ocular tissue and may be activated by external stimulus 70, when the user wishes to focus on a near object, as described hereinabove.

It will be appreciated that the invention is not limited to what has been described hereinabove merely by way of example. Rather, the invention is limited solely by the claims that follow.