Melanin hydrophilic contact lenses

Details Melanin hydrophilic contact lenses Melanin hydrophilic contact lenses

1990-02-16

1992-05-26

Schofer, Joseph L.

Synthetic resins or natural rubbers -- part of the class 520 ser

Synthetic resins

Processes of preparing a desired or intentional composition...

359350, 359361, 252588, 252582, 252587, 424429, 428412, 428441, 527201, 527202, 527203, 8507, 8509, 8512, 8678, 8673, C08J 300

Patent

active

051168847

DESCRIPTION:


DESCRIPTION
DETAILED DESCRIPTION OF THE INVENTION

According to the present invention, a hydrophilic contact lens is disclosed that includes melanin for protecting the eye by acting as a superoxide dismutase agent and by filtering out or absorbing ultra-violet, visible and near infrared radiation. As a result, photochemical damage to the retina, the lens and the cornea of the eye is reduced. The lenses may be prepared with or without an optical prescription for correcting visual defects. Furthermore, the lens may be prepared for either an external or intraocular application.
It is well known that, although the cornea and the lens of the eye absorb most of the damaging rays of the sun or other natural or artificial sources of radiation, including rays belonging in the ultra-violet region, there is a considerable amount of radiation in the wavelength ranging from between 400 and 550 nanometers which reaches the retina and causes photochemical damage. It is also well known that the magnitude and the severity of the damage is increased exponentially as the wavelength of radiation is decreased towards 400 nanometers.
In describing this invention the terms "absorbance", "optical density" or "absorption" are used herein to describe the same property of melanin or melanin hydrophylic contact lenses and, therefore, those terms are the same and are used interchangeably to describe such property. It should be understood that the terms absorbance, optical density or absorption are defined by those skilled in the art as the product of the multiplication of concentration of absorbing material times absorptivity times optical path length. In mathematical terms, this relationship is described and used herein as follows: material).times.(absorptivity).times.(optical path length)
The terms "transmittance" or "transmission" are also used to describe the same property of melanin or melanin contact lenses and, therefore, they are used interchangeably to describe such properties. Furthermore the terms "transmittance" or "transmission" are related to the terms "absorbance", "optical density" or "absorption" by the following mathematical formula: =10 .sup.-Absorption,
Referring now to FIG. 1(a) there is shown the absorbance or optical density of L-Dopa acqueous melanin versus the wavelength of the radiation. The concentration of the acqueous melanin is 0.01 milligrams per milliliter. Referring now to FIG. 2 there is shown the transmittance of the acqueous melanin whose absorbance is shown in FIG. 1(a).
FIG. 1(b) shows the absorbance of 0.1 milligrams of sepiomelanin in a 300 milligram KBr pellet. FIG. 1(b) can be found in the book R. A. Nicolaus, Melanins (1968), published by Herman, Paris, France (hereinafter referred to as the "Nicolaus Book"). Other graphs showing the absorption or other properties of melanins and a comparison of the absorption or other properties of melanin with those of other substances can be found in that book. Those graphs and the information contained in the Nicolaus Book relating to melanins is incorporated herein by reference.
It is clearly shown in FIGS. 1(a), 1(b), and 2 that the amount of radiation absorbed by the melanin continuously increases as the wavelength of the radiation decreases from the higher wavelengths to the wavelengths wherein the amount of damage is the highest. Because the probability, amount, or severity of retinal damage increases exponentially as the wavelength is decreased from the higher wavelengths toward the ultraviolet region of the spectrum, it is apparent, that the absorption spectrum of melanin is very similar to the action spectrum for the retinal damage or, alternatively, that the percentage of radiation absorbed by melanin increases in the ultraviolet wavelength region wherein the potential of retinal damage increases.
It is also believed by certain authorities in the field, that photochemical damage to the cornea is promoted by oxygen that is present in the cornea or in its vicinity. That oxygen dependence has been disclosed by Zuchlich, Photochem. Photobiol., Volume 25, pages 13

REFERENCES:
patent: 2822339 (1958-02-01), Hagemeyer, Jr. et al.
patent: 3322719 (1967-05-01), Pielstocker
patent: 3764477 (1973-09-01), Lehmann et al.
patent: 4404257 (1983-09-01), Olson
patent: 4419405 (1983-12-01), Ashby et al.
patent: 4464525 (1984-08-01), Vance
patent: 4650605 (1987-03-01), Vance
Today-San Antonio.
The Merck Index (10th Edition pp. 266, 827 and 1154).
Hackh's Chemical Dictionary (4th Edition) pp. 413 and 698.
Organic Chemistry, pp. 428, 429, 576, 577 and 579.

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