Cholinergic agents in the treatment of presbyopia

Drug – bio-affecting and body treating compositions – Designated organic active ingredient containing – Having -c- – wherein x is chalcogen – bonded directly to...

Reexamination Certificate

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C514S912000

Reexamination Certificate

active

06291466

ABSTRACT:

Presbyopia, occurring after middle age, is the inability of an eye to focus correctly. This age-related ocular pathology manifests itself in a loss of accommodative ability. Accommodative ability is the capacity of the eye, through the lens, to focus on near or far objects by changing the shape of the lens to become more spherical, or convex.
The ciliary muscle controls the shape of the lens through suspended suspensory ligaments called zonules. Like most smooth muscles, the ciliary muscle has a dual innervation, receiving both sympathetic and parasympathetic fibers.
In the ciliary muscle, the contraction necessary for accommodation is under parasympathetic or cholinergic control. While this parasympathetic control is predominant, sympathetic, or adrenergic, innervation opposes the cholinergic control and plays a lesser role in enabling relaxation of the ciliary muscle.
Most current theories of accommodation assume that the condition of physiological rest of accommodation occurs when the emmetropic eye focuses on a distant target, demanding good resolution. The fact that the optical value for the location of this distant target can be stated as zero diopters from the eye has tended to perpetuate the concept that active accommodation is unidirectional toward a near object.
However, if one considers that if the normal stimulus to accommodation is visual in nature, then the resting state of the eye must be determined by removing all visual stimuli, as for example, in complete darkness or in a luminous but completely empty visual field. This state of rest of the eye has been called “tonic accommodation”, “space myopia” and “sky myopia”, and averages about 1D in extremely low illumination or total darkness but may be as high as 2D myopia.
This implies that the resting state of accommodation is present when the eye is focused for objects about one meter away. Accordingly, distant objects would be focused on the retina by an active negative accommodation and near objects would be focused by an active positive accommodation.
Accordingly, in the natural resting state of the eye, the parasympathetic/cholinergic system maintains ciliary muscle tone, i.e., the ciliary muscle is contracted and zonular tension is relaxed such that the lens is more spherical and in a forward position increasing the refractive power of the eye. Thus, the eye is naturally in a “tonic accommodative” state and with appropriate stimulus is capable of further active positive accommodation as well as active negative accommodation.
SUMMARY OF THE INVENTION
A method in accordance with the present invention provides for increasing or decreasing parasympathetic/cholinergic/ciliary tonic contraction in order to restore the resting position of the eye and allow normal positive and negative accommodation. This action of the ciliary muscle under parasympathetic innervation provides for zonules relaxation which allows the lens to assume a more spherical shape.
A specific method in accordance with the present invention comprises administering to a presbyopic subject an effective amount of a muscarinic agonist or antagonist.
The agonist/antagonist is administered in a pharmaceutically acceptable ophthalmic formulation, preferably the agonist is administered topically by application of the formulation to the eye in a non-irritating sterile solution or suspension. In that regard, the formulation is preferably at a pH compatible with the eye. More particularly, in accordance with the present invention, a muscarinic agent may be selected to act on various M receptors of the ciliary muscle.


REFERENCES:
patent: 5122522 (1992-06-01), Laties et al.
patent: 0 369 880 (1989-11-01), None
patent: WO 90/15604 (1990-12-01), None
patent: WO 94/01096 (1994-01-01), None
XP-000866125 Review of Ciliary Muscle Effort in Presbyopia vol. 61.No.2pp. 133-138 By Jess B. Eskridge From American Journal of Optometry & Phsiologocal Optics 1984.
XP-000866126 Pilocarpine in the Presbyope—Demonstration of an Effect on the Anterior Chamber and Lens Thickness By David H. Abramson, et al 100 Arch Opthalmol. vol 89, Feb. 1973.
XP-000866173 Age-dependent loss of accomodative amplitude in rhesus monkeys; an animal model for presbyopia By L. Z. Biot, et al.
XP-000866355 Japanese artical Accommodation was observed of 27 subjects of bothe sexes . . . By Akihiro Suzumura, et al Accommodation in Presbyopics Influenced by Aging and Extensive Medication.
XP-000866560 Japanese artical In 80 subjects between the age of 35 and 50, the effects . . . By Hiroshi Ichikawa Central Hospital of Japanese National Railways.
XP-000870258 Effect of topical carbachol on the pupil and refraction in young and presbyopic monkeys By Goran Tornqvist 1966.
XP-002128588 Aluminum Sodium Sulfate 1996.

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