‘CONTACT’ IN SPACE LEADS TO NEW LENSES
HEALTH AND MEDICINE
ORIGINATING TECHNOLOGY/NASA CONTRIBUTION
While gravity has its advantages
in keeping us balanced and grounded here on Earth,
scientists often find that they are at a disadvantage
when trying to conduct research under its powerful,
pulling influence. In these instances, the scientists
prefer performing their studies in the weightless
atmosphere of microgravity, where gravity is greatly
reduced and solids, liquids, and gases behave differently.
In
1993, Paragon Vision Sciences, Inc., of Mesa, Arizona,
participated in a research project with NASA’s Langley
Research Center to perfect a process for developing
contact lenses. The project called for three experiments
that would fly onboard the Space Shuttle over the
course of three separate missions, from 1993 to 1996.
By unleashing contact lens materials to the microgravity
settings of space, scientists from NASA and Paragon
hoped
to better understand how polymers—large molecules
that make up plastics—are formed.
PARTNERSHIP
At Paragon,
a manufacturer of premium performance plastics used
in gas permeable contact lenses, scientists must
perform a complicated process called polymerization
to ensure that the materials they are using to make
contact lenses are nontoxic, highly biocompatible,
extremely permeable to oxygen, durable under abrasive
cleaning conditions, wettable, transparent, and machineable.
Given all
of these
divergent properties, it is necessary for
the Paragon scientists to synthesize polymer chains
wherein the various links in the chains are of substantially
different chemical character.
 |
| Paragon Vision Sciences, Inc. and Langley Research Center designed experiments
to go into space aboard the Space Shuttle, in
order to perfect a process for developing contact
lenses. |
During polymerization,
some of the links are preferably incorporated into
the growing chains
simply due to their compatibility to the environment
of the chains. The result, however, is an uneven
distribution of these “precursor” links in the final
polymer, leading to an uneven distribution of properties
throughout the final product. This can be detrimental
in developing materials for contact
lenses.
To avoid this consequence, it is essential
to minimize the redistribution of the precursor links
during polymerization. While many of the driving
forces for redistribution can be restrained in laboratories
on Earth, one cannot:
convection, the response to density differences arising
from uneven heating in the reaction mixture. Since
convection is driven by gravity, it was apparent
to Paragon scientists that the microgravitational
atmosphere
of space was the only environment where they could
correctly study
the properties of new polymer formulations plagued
by this problem.
Paragon and Langley designed three
experiments to go into space on Shuttle Missions
STS-57 (Endeavor), STS-63 (Discovery), and STS-77 (Endeavor) and explore such formulations. The “Gas
Permeable Polymer Materials” experiments were performed
in SPACEHAB, a pressurized research laboratory within
the Space Shuttle’s cargo bay that was created for
scientific and commercial experimentation.
The Space
Shuttle research showed which plastic formulation
components made the strongest contributions to the
nonuniformity
and lesser permeability characteristics
seen in similar formulations made on Earth (permeable
plastics are ideal for extended-wear contact lenses
because they allow more oxygen to reach the cornea,
which is vital to preventing swelling of the eye).
For Paragon, the findings led to an improved ground-based
synthesis process and yielded new and better polymers
for advanced uses in treating vision problems.
PRODUCT OUTCOME
Paragon’s HDS® (hyperpurified
delivery system) contact lenses are based on the
unique technological advancements derived from the
company’s experiments with NASA. HDS lenses are considered
gas permeable, and therefore
do not contain water, are resistant from deposits,
and are less likely than soft contact lenses to harbor
bacteria. The rigidity of gas permeable contact lenses
also makes them easier to handle than soft lenses,
plus
they retain their shape over time to provide crisper
vision.
The HDS line effectively eliminated “bad”
silicones, making the lenses extremely oxygen efficient.
HDS has been approved by the U.S. Food and Drug Administration
(FDA) for up to 7 days of continuous wear. Along
with this approval, HDS was the subject of the most
complete and comprehensive study on gas permeable
extended-wear lenses ever conducted, according to
Paragon. The National Institutes of Health-sponsored
study confirming the safety and efficacy of the lenses
was performed over a 5-year period and published
in the August
2001 edition of the peer-reviewed journal, Ophthalmology.
Paragon
additionally leveraged what it learned from the Space
Shuttle experiments to invent a contact lens made
from HDS materials that nonsurgically reshapes the
cornea during sleep. Paragon CRT® (Corneal Refractive
Therapy) is the company’s latest product and the
first therapeutic lens design approved by the FDA
for overnight Corneal Refractive Therapy for the
temporary reduction of myopia, or nearsightedness,
with or without moderate astigmatism. When users
awake, they simply remove the CRT lenses and experience
clear, natural vision without daytime contact lenses
or glasses. The FDA approval was based on results
of an extensive and successful study in which
almost 70 percent of the patients wearing the CRT
contact lenses achieved 20/20 vision or better and
more than 93 percent achieved 20/32 vision or better,
which exceeds the 20/40 vision acuity that most states
require to drive a car with an unrestricted license.
 |
| Paragon Vision Sciences, Inc.’s CRT® (Corneal Refractive Therapy) contact lens
is a noninvasive alternative to laser-corrective
surgery, as it reshapes the cornea during sleep
to reduce nearsightedness. When users awake,
they simply remove the CRT lenses and experience
clear, natural vision without daytime contact
lenses or glasses |
“Consumers
no longer have to tolerate daytime contact lens irritation
due to dry eyes, interference of glasses or contacts
during sports and recreation, and countless other
hassles,” asserts Joe Sicari, Paragon’s president
and chief executive officer. “Further, consumers
now have a nonsurgical option to gain the benefits
of device-free vision.
”Not
only is Paragon CRT a noninvasive alternative to
laser-corrective surgery, there are no age restrictions.
The process is also reversible, so if a user wishes
to discontinue wearing the lens, the cornea will
return to its original shape. Moreover, Paragon CRT
allows
for adjustments
for normal changes in vision that occur as people
age.
Paragon has trained and certified over 2,000
eye care practitioners nationwide to prescribe Paragon
CRT for overnight Corneal Refractive Therapy and
tens of thousands of consumers are already enjoying
the benefits of this safe, remarkable technology.
The process is
years ahead of the conventional methods of orthokeratology,
which also depend on contact lenses to nonsurgically
reshape
the cornea, but take months to accomplish the desired
result.
HDS® and CRT® are registered trademarks of
Paragon
Vision Sciences, Inc.
|
