Anyone about to undergo laser eye surgery has to sign a long form giving
informed consent to the operation after reading about all possible
complications. But if you want contact lenses on your corneas instead of glasses
on your nose, neither the optometrist nor the ophthalmologist who prescribes
them is obligated to get you to sign such a document.
In the US alone,
more than 70,000 children and teens go to the emergency room each year for
injuries and complications from medical devices – and contact lenses are the
leading culprit, according to the first detailed national estimate, publicized a
few weeks ago. About one-fourth of the problems were things like infections and
eye abrasions in contact lens wearers. These are often preventable and can
result from wearing contact lenses too long without cleaning them.
the vast majority of contact lens users manage to use them without ill effects,
even the relatively small number who suffer serious infections are a lot of
people, considering an estimated 125 million around the world wear
IN FACT, the Italian sculptor, painter, architect, scientist,
engineer, musician, inventor, mathematician, geologist and anatomist of the 15th
and 16th centuries, Leonard da Vinci, is credited with presenting the first
ideas for contact lenses. He both described and drew them. But it took more than
three centuries after his death before a German glassblower, F.E. Muller,
produced the first eye covering to be seen through and tolerated and his
compatriot Adolph Fick built the first successful contact lens.
early lenses made of glass, the first lenses made of polymethyl methacrylate
(PMMA or Perspex/Plexiglas) were designed by William Feinbloom, which made them
much more user friendly, but they were still inflexible. The first modern soft
contact lenses were invented in 1961 by Czech chemist Otto Wichterle and his
assistant Drahoslav Lim, who also invented the first hydrogel used to produce
them. Almost four decades later, silicone hydrogels that allow much more oxygen
in were developed, and these were followed by even more advances.
types of contacts are used in the entertainment industry to make the eye look
cloudy, dilated as if taking illegal drugs or lifeless, as for horror movies.
And there are some people who obtain lenses to “change” their eye color. The
convex spheres can also treat vision problems – such as abnormally shaped
eyeballs – that glasses cannot. One type of lenses have been shown even to make
it easier for dyslexics with neurological rather than vision problems to read
better, while another helps the color blind to differentiate better among
colors. A rare type of contact lens is worn to cover defects such as the lack of
an iris (the colored part of the eye) or damage to it. A “bandage contact lens”
can be therapeutic, protecting a diseased or injured cornea from the constant
rubbing of blinking eyelids. They are used to treat dry eyes, corneal ulcers,
bullous keratopathy, anterior corneal dystrophy and other disorders. There are
even drug-delivering contact lenses.
BUT COMFORT and personal appearance
are the main reasons why the majority of people prefer contacts to glasses. When
the eye’s length and refractive power are not matched, a refraction error is
produced. Contacts can neutralize this and help the wearer’s eyes focus the
light onto the retina properly.
Lenses can correct near- and
far-sightedness, astigmatism (a common condition of blurred vision when the
cornea is not perfectly spherical) and presbyopia (in which the lens in the eye
becomes less able to focus on near objects as people age).
Varssano, head of the cornea clinic at Tel Aviv Sourasky Medical Center and
former chairman of the Israel Cornea Society, spends much of his time treating
contact lens wearers suffering from infections and other
“Some are treated in the emergency room,” he told The
in an interview, “while others come to our clinic and some are
Ours is one of the largest hospitals in the country;
we we get many people with contact lens complications. Others are, of course,
treated by ophthalmologists in the community.”
Eyeglasses, he noted, save
the wearer lots of money, but that will not convince those who decide on contact
lenses. While laser surgery to remove glasses has become very popular, Varssano
has not noticed that this option has reduced the number of people wearing
Although in some parts of the world, opticians who merely
sell glasses are permitted to “prescribe” and sell contact lenses, in Israel
they have no license to do so; only the ophthalmologist, a physician who
specializes in treating the eyes, or an optometrist who fits people with glasses
and other eyewear, may do so. Contact lenses can even be ordered over the
Internet, once one knows what to order, but doing so alone, without a medical
address close by, is not safe. Varssano said many wearers are absolutely
“They come to the hospital with a serious corneal infection
that poses a risk to their sight and don’t understand what I’m talking about.
They think contact lenses, which hug the eye, are as safe as eyeglasses! But
some of them lose their sight or may need a cornea transplant.” The Sourasky
ophthalmologist added that he didn’t know what optometrists tell their customers
about possible dangers of lenses, but “most of them claim they knew nothing
about these risks.”
In any case, those who wear lenses have to bear
responsibility for their eye health. The vast majority of contacts wearers that
he encounters are young people.
Children also wear contact lenses. While
he has a feeling that those under 18 have relatively more infections than
adults, Varssano says he has no statistics to back this up. “Relatively few
people over 50 wear them; they opt for eyeglasses.”
impermeable lenses account for over a fifth of those worn in Germany, Japan and
the Netherlands, they are not common in Israel and in places like Scandinavia.
Their advantage is that, because they have no pores, hey don’t absorb chemical
fumes, so they would be beneficial for people whose occupation involves exposure
to such harmful substances. Most of the rigid lenses used in Israel are
gas-permeable substances that allow oxygen to get through to the cornea. While
gas-permeable rigid lenses let in more oxygen, they are “less easy to wear. You
can feel them on the eye.
People don’t like them as much as soft lenses,”
said Verssano, who has been at Sourasky for 21 years.
The most important
lens safety rule – besides the need to clean and disinfect them as prescribed
and wash your hands with soap and water before inserting or removing your
contacts – is never to leave them on while sleeping. This, said the
ophthalmologist, not only reduces oxygen supply to the delicate tissue but also
allows debris to accumulate and bacteria to grow on your corneas.
wearers are putting a plastic object on a very fragile part of the eye. They
have to be careful.”
Although extended-wear contact lenses can be worn
continuously for about a week at a time, Varssano does not recommend
The appearance of silicone hydrogels 11 years ago offered high
permeability of oxygen, but although manufacturers initially said they can be
worn overnight, in recent years they have not been approved by the health
authorities for overnight use.
Like eyeglasses, noted Varssano, contact
lenses can have one (single vision) or more (multifocal) focal points. But
multifocal soft contact lenses are more difficult to manufacture and
Ironically, in recent years there has been renewed interest in
orthokeratology – the correction of myopia (nearsightedness) by deliberate
overnight – temporary – flattening of the cornea, so that the wearer can see
better without the lens in the eye during the day. As could have been expected,
said Verssano, multiple reports of infectious bacterial keratitis following the
use of such lenses have been published.
Some users of conventional lenses
suffer from allergies, dryness or chronic eye infections. They may also have
conjunctivitis – an acute inflammation of the conjunctiva, the outermost layer
of the eye and the inner surface of the eyelids, most commonly due to an
allergic reaction or an infection, But infectious bacterial keratitis, which is
a potentially dangerous acute condition of the cornea itself, develops in only a
few days and can be painful.
“We usually treat keratitis with antibiotics
drops, since an infusion of antibiotics is less effective. But often we have to
take a culture, and patients have to be under observation. One growing problem
is that bacteria develop resistance to antibiotics. “We can’t solve all problems,” he concluded.