LASIK vision correction can be used in presbyopic patients. There are
two basic methods which can be applied. One method creates a
multifocal zone in the central area of the cornea. The effect is
similar to the use of multifocal eyeglasses or contact lenses. The
other method, called "monovision," corrects the two eyes differently
so that one eye is suited for distance vision, and the other for
close-up vision. Unfortunately, there are problems associated with
both these methods, and a solution that is fully satisfactory to all
patients has not yet been found. Trials are underway on several new
techniques, so the future looks promising.
I've gathered some info that will give you an overview of the subject.
For reasons of copyright, I've posted just brief excerpts; you may
want to read the articles in their entirety. It should be noted that
the multifocal surgery discussed below has not been approved by the
FDA, although it is available abroad. Monovision LASIK is widely
available worldwide.
"Because its causes are fundamentally different from those of myopia,
hyperopia, and astigmatism, many ophthalmologists have concluded that
there is no cure for presbyopia and that the only solution is for
patients to wear reading glasses to compensate for their inability to
focus at near. Toward the end of 1993, my associates and I began to
develop a method for treating presbyopia that we believe will be the
next frontier in refractive surgery. We have currently corrected
approximately 1,500 eyes, and our results are continuing to improve.
Our goal is to create satisfactory visual acuity for distance and near
vision for both eyes simultaneously.
ADDRESSING PRESBYOPIA IN THE CORNEA
We call the developing technique presbyopic LASIK. It involves
constructing a flap and precisely forming an annular ablation in a
centralized region of the newly exposed corneal stroma. This technique
produces an unablated central protrusion of the stroma and transforms
the exterior surface of the preplaced flap into a multifocal surface
that effectively provides good distance visual acuity of 20/25 or
better and near vision of J2 or better...
We have observed that patients treated with presbyopic LASIK recovered
their near vision on the first postoperative day and have experienced
no regression. Distance vision, however, required between 2 and 3
months on average to return to its maximum function."
Cataract & Refractice Surgery Today: Presbyopic LASIK
http://www.crstoday.com/03_archive/1002/crst1002_201.html
"CAN refractive surgeons provide presbyopic patients with both
satisfactory reading and distance vision? Two pioneering refractive
surgeons presented contrasting viewpoints on this issue at the
Congress of the German Ophthalmic Surgeons (DOC).
'What we term 'presbyopic LASIK' is a surgery we developed that
effectively provides the presbyopic patient with good distance visual
acuity of 20/25 or better and near vision of J2 or better. We reshape
the central 3 mm zone to be multifocal but leave the most peripheral
area of the cornea unchanged for intermediate and distance vision,'
asserted Luis A Ruiz MD, Scientific Director of the Centro
Oftalmologico Colombiano Bogota, Bogota , Colombia . Dr Ruiz and his
colleagues in Bogota performed close to 1,500 presbyopic LASIK
corrections since 1993 when they began developing this specialised
surgery. Dr Ruiz described the procedure as involving a corneal flap
and the formation of a precise annular ablation in the central zone of
the newly exposed corneal stroma. This leaves an un-ablated central
protrusion of the stroma and transforms the exterior surface of the
replaced flap into a multifocal surface, he said."
Presbyopic LASIK - the final frontier
http://www.escrs.org/eurotimes/November2003/Presbyopic_LASIK.asp
"Houston surgeon Jack Holladay... thinks that ablating a peripheral
zone and leaving one in the center for distance is just another kind
of multifocal cornea patterned after similar unsuccessful multifocal
IOLs [intraoptical lenses].
'The reason the annulus doesn?t work well is because when the patient
looks up close to read at near, his pupil constricts and gets inside
the annulus that he needs for near vision. And, at night, when he
walks outside and wants to look in the distance, that annulus is right
down the barrel of where he?s looking, so he gets a dramatic loss of
contrast and sees halos around lights.'
He says that, though every kind of multifocal lens is available in
contact lenses, too, from bull?s-eyes to annuli, only 5 percent of
contact lens wearers choose them. 'If it were that great a concept, we
wouldn?t have only 5 percent of contact lens wearers in multifocal
contact lenses and 10 percent in monovision,' he argues. 'Eighty-five
percent still wear readers because they?d rather have crisp vision at
other distances.'
He says that one ablation strategy that has potential for presbyopes
is a variation on a theme that he has advocated repeatedly: the
prolate cornea... Until companies and surgeons move in that direction,
though, Dr. Holladay says things will be 'the same story 15 years
later - it?s the same for corneal presbyopic surgery as it was for
multifocal IOLs, which came 15 years after multifocal contacts. But,
the experience on the cornea is going to be identical and even a
little worse because you can?t control [the zones] as well due to
corneal healing and you can?t, unlike contacts, do a couple lens
changes to get it working right for a particular patient."
Review of Ophthalmology: Is Presbyopic LASIK Coming into Focus?
http://www.revophth.com/index.asp?page=1_461.htm
"Theo Seiler MD, Institute for Refractive and Ophthalmic Surgery and
professor at the University of Zurich , Zurich , Switzerland , has had
good results with creating monovision in his presbyopic patients. 'We
have been using LASIK to create monovision since the early 1990s, with
very satisfying results. It seems to be important to make the dominant
eye emmetropic, while the second eye remains slightly myopic (around
-1.0 D)," he said. He recommended that patients simulate monovision
before undergoing surgery by wearing contact lenses, to test whether
the individual patient is suited to monovision. Patients with higher
astigmatism may not have this option, but the surgeon may still
operate the patient at his request.
Refractive surgeons can perform re-ablation one month following the
initial surgery for patients that are not satisfied with their
results. 'Presbyopic LASIK corrections are still in the scientific
testing stages. Creating a multifocal cornea, such as supported by Dr
Ruiz, is responsible for both reduced high- and low- contrast
sensitivity. Many patients opt for monovision instead. We performed
presbyopic LASIK in the 1990s by creating a centralised
undercorrection, a kind of 'central steep island'. The overall results
were disappointing. The price for the pseudoaccommodation was an
increased light sensitivity and reduced visual acuity,' Dr Seiler
reported.
'Many patients were unhappy with the visual results and malpractice
suits centred on the loss of vision due to the surgery."
Presbyopic LASIK - the final frontier
http://www.escrs.org/eurotimes/November2003/Presbyopic_LASIK.asp
"Monovision is an option for people with presbyopia where the two eyes
are adjusted to have slightly different focusing points. One eye will
see things close up, the other eye will see things farther away, and
the brain will integrate the visual information from both and filter
out any blur. With monovision, you do not need to make any conscious
adjustments in how to see, and the brain usually adjusts within 6-8
weeks to each eye focusing at a different distance.
Monovision has been used successfully with contact lens and refractive
surgery patients for over 20 years. Refractive surgery patients can
achieve monovision either with conventional laser vision correction or
conductive keratoplasty (CK), a new, minimally invasive, non-laser
vision correction procedure. The CK procedure uses a technique called
'blended vision,' a type of monovision that many people have found
easier to adjust to. Ask your doctor if blended vision might be right
for you.
Monovision refractive surgery is not a cure for presbyopia. It simply
're-sets' the clock for near vision, giving you an additional 5 to 10
years without the need for reading glasses for most tasks. Even with
monovision, however, there may be some situations (such as night
driving in unfamiliar areas) where you might require 'special needs'
glasses.
The decision to have monovision refractive surgery is dependent on
your age, profession, hobbies and desires... It is a good idea to
simulate monovision on a trial basis to see if you can get used to
your eyes focusing at different distances."
Furlong Vision Correction: Presbyopia/Monovision
http://www.furlongvision.com/presbyopia_monovision.html
"Monovision is a form of treatment for presbyopia. One eye is fully
corrected for distance vision, while the other is under corrected.
This will leave the under corrected eye with a mildly myopic
prescription (nearsighted) for near vision.
The distance vision in this under corrected eye is blurrier, but the
near vision is sharper. This small amount of myopia allows a
presbyopia (over 40 years old) patient to see clearly up close, and
therefore can avoid or reduce the need for reading glasses.
This situation is a compromise. It does not eliminate presbyopia, but
improves it. Distance vision is not perfect, but good. Near vision is
not perfect, but good enough to function."
Lasik MD: Monovision
http://www.lasikmd.ca/monovision.html
Other useful sites:
Laser Eye Center of Silicon Valley: Monovision FAQ
http://www.2020eyesite.com/html/faq_monovision.php
All About Vision: Surgery for Presbyopia
http://www.allaboutvision.com/visionsurgery/presbyopia_surgery.htm
Ophthalmology Times: Monovision LASIK worthwhile for age-appropriate candidates
http://www.ophthalmologytimes.com/ophthalmologytimes/article/articleDetail.jsp?id=93980
Review of Optometry: Surgery for ?Short Arm Syndrome?
http://www.revoptom.com/index.asp?page=2_1062.htm
Access Excellence: OPHTHALMOLOGISTS ENVISION BRIGHT FUTURE FOR AGING EYES
http://www.accessexcellence.org/WN/SU/presbyopia.html
Google search strategy:
Google Web Search: "lasik" + "prebyopia OR presbyopic"
://www.google.com/search?hl=en&ie=UTF-8&q=lasik+prebyopia+OR+presbyopic
Google Web Search: "presbyopia OR presbyopic" + "monovision" + "lasik"
://www.google.com/search?hl=en&ie=UTF-8&q=presbyopia+OR+presbyopic+monovision+lasik
I hope this information is useful. If anything is unclear, or if a
link doesn't work for you, please request clarification; I'll be glad
to offer further assistance before you rate my answer.
Best regards,
pinkfreud |
