Symptoms and Complications
The main symptoms of farsightedness are difficulty seeing near objects clearly,
headaches, and eye strain.
You might think that farsightedness would be obvious to an adult. If your morning
newspaper is getting increasingly blurred, you're likely to notice. In reality,
the process is sometimes just too slow for the brain to detect. Farsightedness
in children also often goes unnoticed. Some children born with farsightedness
have never seen close objects clearly and may not be aware that it's possible
to see them better. Also, hyperopic children can sometimes see close objects
clearly by unconsciously straining their eyes. In such children, the main symptom
of hyperopia may be headaches, not blurring.
Current research is investigating a possible link between farsightedness in
children and poor reading and school performance. Children who may appear to
lack an interest in reading quite often turn out to be slightly farsighted.
Many older people with farsightedness have a great deal of difficulty reading.
Fortunately, farsightedness doesn't usually interfere with your ability to drive
a car.
Making the Diagnosis
Eye doctors use the well-known poster with rows of smaller and smaller letters,
called the Snellen sight card, to look for nearsightedness (myopia),
but it can't detect farsightedness. This is why it's often missed in school
eye tests. A proper eye test in an optometrist or ophthalmologist's office involves
sitting in a chair with a device called a phoropter or refractor
attached at eye level. You look through the device at a wall poster and the
eye doctor slips various lenses in and out of your field of view. This test
can detect both farsightedness and nearsightedness.
Treatment and Prevention
You can't prevent farsightedness, but you certainly can treat it. There
are three options: glasses, contact lenses, and laser surgery.
Glasses can correct almost any type of vision problem. They're particularly
useful for people with poor vision at both long range and very close range,
because they can use "bifocal" lenses. Looking through the upper lens
gives you long-range vision, while looking through the lower one gives you close-range
vision.
Contact lenses can also correct these problems. Lenses with high correction
factors (i.e., those made to correct very poor vision) are likely to
be thicker and heavier than weak lenses and some people find them uncomfortable.
This is particularly true of lenses that correct for astigmatism. There are
also bifocal contact lenses, but some people find them difficult to use. Soft
lenses are generally taking the place of hard and gas-permeable versions, as
they're more comfortable and easier to adjust to, though they may be harder
to clean. Wearing lenses makes you somewhat more prone to eye infection - this
risk can be minimized by cleaning them according to instructions, throwing away
disposables on time, and never sleeping with the lenses in.
Laser surgery, originally developed for myopia, can now also treat hyperopia.
The most common techniques are called holmium laser thermokeratoplasty
(LTK), hyperopic photorefractive keratectomy (H-PRK), and laser-assisted
in situ keratomileusis (LASIK).
In LTK, a laser removes the epithelium, the very top layer of the front
of the eye, then ablates (destroys) a measured layer of the cornea, following
preset instructions from a computer. In H-PRK, a computer-controlled laser removes
the epithelium and reshapes the cornea by ablating tissue in the periphery or
outer part. LASIK is much the same, except that a flap is cut in the epithelium
with a diamond blade, then the laser removes tissue from the cornea, and the
flap is put back in place, where it sticks without glue or stitches.
Newer refinements of these procedures are constantly under development. One
example is "wavefront" or "custom" LASIK, in which a computer
maps the visual problems needing correction, increasing the accuracy of the
result.
Both techniques are about equally effective in improving sight. Infection of
the area that was operated on may occur day or two after the operation, but
usually it's easily treated with antibiotics. The operations themselves are
quick (less than several minutes per eye) and painless, though the eye will
sting for a few days afterwards. Laser surgery can only be performed on uninfected
healthy eyes. It isn't suitable for children and teenagers, because their vision
is still changing.
Eye operations don't always produce the desired results. Study results
vary, but between about 50 to 60% of farsighted people who have laser surgery
(LASIK procedure) for hyperopia end up with 20/20 vision. And 93 to 98% of farsighted
people have at least 20/40 vision. However, some people do not notice any improvement
in their vision, and a few end up with poorer vision.
Laser surgery can reduce the quality of your best-corrected vision (the absolute
best you could see with the right lenses). It can also reduce night vision.
In addition, having the operation doesn't mean the eye is permanently "fixed" - it
can change again. Sometimes, it heals from surgery into much the same shape
it had before, producing only temporary improvement. Because eye doctors like
to err on the side of caution, they may "undercorrect" vision, and
you may need follow-up procedures. You should discuss these potential complications
thoroughly with your eye doctor before opting for laser surgery.
Finally, since these procedures are fairly new, we don't know the lifelong
consequences. Most people are still seeing well 10 years after surgery,
but we don't know how they'll be seeing 30 years from now. While there's no
reason to believe they'll have problems, we can't be absolutely sure.