Hello 28837-ga
Firstly, to define the terms:
LASIK stands for laser-assisted in situ keratomileusis, and
keratomileusis is “Surgical alteration of refractive error by changing
the shape of a deep layer of the cornea: the anterior lamella is
peeled back, frozen, and recarved on its back surface on a lathe; or,
some of the corneal stroma can be removed from the bed with a laser or
a knife.”
Keratoconus is “A conical protrusion of the cornea caused by thinning
of the stroma; usually bilateral.”
Definitions from my own copy of Stedman’s Medical Dictionary. Some of
the content of the dictionary can be searched on the Stedman’s web
site: http://www.stedmans.com/
A web page showing the anatomy of the cornea and describing the
function of the component tissues is available at
http://www.stlukeseye.com/anatomy/Cornea.asp (web site of St. Luke's
Cataract & Laser Institute)
My research for you has shown that the use of LASIK and other laser
excimer procedures in patients with keratoconus can be associated with
an increased risk of ectasia. Corneal ectasia is a progressive
thinning and bulging of the cornea, which can have adverse visual
consequences because the tissue becomes abnormally thin and thus
biomechanically unstable. As pointed out in the definition of ectasia
in the Glossary of Vision and Eye Terms by David A. Wallace MD
http://www.la-sight.com/LS_glossary.asp , keratoconus itself is “a
type of corneal ectasia, characterized by thinning and steepening of
the central or paracentral cornea.” Thus, excimer laser procedures
could worsen the very condition they are trying to treat. As you will
see from the studies cited below, clinical experience is mixed. Some
authors claim that LASIK and similar procedures can be used
successfully in cases of keratoconus, early keratoconus or forme
fruste keratoconus, while others report complications. For example,
one group of authors found that 88% of all cases of postoperative
ectasia were associated with pre-operative forme fruste keratoconus.
According to Stedman’s Medical Dictionary, forme fruste means “A
partial, arrested, or inapparent form of disease.” A 1999 paper by
Buzard and colleagues, detailed below concludes that they no longer
consider LASIK to be a primary solution for keratoconus.
The studies I found follow below. My strategy was to search Medline
on Pubmed http://www.ncbi.nlm.nih.gov/entrez/query.fcgi using the
search term keratonus together with the search term laser or LASIK. I
took the liberty to widen the search to cover excimer laser
keratectomy, since a number of authors discuss both of these
procedures together, implying that the risk factors and complications
are similar. The procedure is very similar to LASIK. The difference
is that in the first case, the laser is used to remove the surface of
the cornea, while in LASIK the outer layer is moved to one side and
the laser is used on the internal part of the cornea, with the surface
layer then being moved back into position. This is thought to result
in faster healing. (Information from
http://www.hendrickhealth.org/healthy/001058.htm - web site of the
Hendrick Health System).
The earliest paper I found in Medline about the use of excimer laser
to treat keratoconus patients is a Polish report from 1992. The
authors report on the treatment of 10 eyes in 8 patients with
keratoconus, for the purposes of reducing astigmatism. In a very short
abstract, they specifically mention that they did not observe any
damage to Descemet’s membrane. If you refer to the St Luke’s URL
referenced above, you will find that Descemet’s membrane lies between
the stroma and the endothelium. The endothelium consists of only one
layer of cells. Its purpose is to keep the cornea clear by supplying
it with water. If it is damaged, the damage is permanent. The
possibility of damage occurring to Descemet’s membrane and the
endothelium is therefore one concern regarding the use of this
procedure.
Klin Oczna, 1992, Volume 94, pages 349-350
[Preliminary report on the use of excimer laser in treating
keratoconus]
[Article in Polish]
Gierek-Kalicka S, Wygledowska D, Mrukwa E.
Abstract at: http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=1341304&dopt=Abstract
Another 1992 paper reports on the after effects of excimer laser
photoablative keratectomy and provides further information about
epithelial damage. The authors examined corneal tissue that had been
removed as part of routine surgical procedures from patients who had
previously undergone excimer laser photoablative keratectomy. They
found that 85 of 130 (65%) corneas from patients with keratoconus
showed compensatory hyperplasia of the corneal epithelium. They
concluded that this hyperplasia occurs more frequently in conditions,
including keratoconus, where there is stromal loss or stromal ectasia.
Ophthalmic Surgery, 1992, Volume 23, pages 729-732
Compensatory epithelial hyperplasia in human corneal disease.
Dillon EC, Eagle RC Jr, Laibson PR.
Abstract at: http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=1484663&dopt=Abstract
Hyperplasia is the abnormal growth of cells, which leads to an
increase in the bulk of the tissue. It gives rise to two types of
postoperative complications, as described in “LASIK Complications
Linked to the Epithelium; Belgian Surgeon Tells When and How they
Occur And How to Manage Them” by John F. Henahan on the web site of
ESCRS (European Society of Cataract and Refractive Surgeons) at
http://www.escrs.org/eurotimes/May2001/lasikcomplicationslinkedtoepithelium.asp
From this, it can be concluded that patients with keratoconus, by
being more likely to develop hyperplasia, are expected to be more
likely to suffer from postoperative complications after excimer laser
treatment.
An article published by Swedish authors in 1994 reported the
successful use of excimer laser treatment to correct keratoconus in
five eyes. The patients were followed up for 6-12 months. The authors
report: “There were no problems with wound healing or any signs that
the excimer adversely affected the cornea or activated the keratoconus
disease process. CONCLUSION: The treatment of keratoconus with excimer
laser has been regarded as seriously contraindicated on a speculative
basis. This risk seems to be exaggerated.”
Refractive Corneal Surgery, 1994, Volume 10, pages 368-372
Excimer laser photorefractive keratectomy for treatment of
keratoconus.
Mortensen J, Ohrstrom A.
Abstract at http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=7522096&dopt=Abstract
It seems though that by 1996, the consensus was not to use excimer
laser techniques on patients with keratoconus, as in this statement:
“Keratoconus is generally held to be an absolute contraindication for
photorefractive keratectomy” [= excimer laser photoablative
keratectomy]. These authors go to say “there seems to be a group of
patients with a stable inferior steepening pattern on topography who
show no other characteristics of clinical keratoconus”. Having
successfully treated four such patients, they conclude “We feel that
the corneal topography pattern of inferior steepening is not always a
contraindication for PRK.” The criteria used to select these patients
were: “aged over 35, with a stable refraction, no slit-lamp signs of
keratoconus, and a corrected vision of not less than 6/7 (0.9) with a
spherical spectacle correction”.
British Journal of Ophthalmolgy, 1996, Volume 80, pages 25-28
PRK in patients with a keratoconic topography picture. The concept of
a physiological 'displaced apex syndrome'.
Doyle SJ, Hynes E, Naroo S, Shah S.
Abstract at http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=8664226&dopt=Abstract
However, in 1997, a French article concluded, “Excimer laser, under
its therapeutic approach, might be an efficient treatment for advanced
keratoconus, in conditions of cautious indications selection and of an
inevitable coupling to contactology. Then, this surgery could delay or
even avoid penetrating keratoplasty.” [keratoplasty = corneal graft].
Following the treatment of eight cases, the only complication noted
was a denser and longer postoperative haze.
J Fr Ophtalmol, 1997, Volume 20, pages 758-766
[Is there a role for Excimer laser in the treatment of keratoconus?]
[Article in French]
Cochener B, Le Floch G, Volant A, Colin J.
Abstract at http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=9587590&dopt=Abstract
In 1998, 4 years after their initial statement that the risk of laser
treatment in keratoconus has been exaggerated (see above), Morton and
Ohrstrom published the findings of 6-46 month followups in 23
keratoconus patients treated with excimer laser keratectomy and
concluded “All treated corneas healed, and no acceleration of the
keratoconus was seen. CONCLUSION: No increased risk was associated
with treating primary keratoconus with excimer laser PRK. We found
that excimer laser surgery can improve vision and the ability to wear
contact lenses, and it did not interfere with subsequent corneal
transplantation surgery.”
Journal of Cataract and Refractive Surgery, 1998, Volume 24,
pages:893-898
Excimer laser surgery for keratoconus.
Mortensen J, Carlsson K, Ohrstrom A.
Abstract at: http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=9682106&dopt=Abstract
On the other hand, another 1998 paper in the same journal reports the
loss of visual acuity from 20/20 to 20/80 following LASIK treatment in
a case of forme fruste keratoconus, and the authors conclude “Corneas
with forme fruste keratoconus may have altered biomechanical
properties compared with normal corneas. Forme fruste keratoconus may
be a contraindication for LASIK.”
Journal of Cataract and Refractive Surgery, 1998, Volume 24, pages
1007-1009
Iatrogenic keratectasia after LASIK in a case of forme fruste
keratoconus.
Seiler T, Quurke AW.
Abstract at http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=9682124&dopt=Abstract
A similar warning against the use of LASIK in early keratoconus or a
forme fruste of keratoconus is made in a 1998 German article “It is
especially important to rule out an early keratoconus or a forme
fruste of keratoconus preoperatively since keratectasia with
particularly rapid progression can occur in such cases: we would like
to designate this as "malignant keratoconus"”. This conclusion was
based on the following results: “LASIK treatment was performed
elsewhere in two patients to treat myopia or myopic astigmatism
between -6 and -9 diopters (D). An astigmatism of -6 D was corrected
with the LASIK method in another patient with keratoconus. Progressive
corneal ectasia of up to seven diopters occurred in all four eyes
within a few months”
Klin Monatsbl Augenheilkd, 1998, Volume 213, pages 247-251
[Progressive corneal ectasia after laser in situ keratomileusis
(LASIK)]
[Article in German]
Speicher L, Gottinger W.
Abstract at http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=9848072&dopt=Abstract
A 3 year followup of 6 patients with mild keratoconus treated with
excimer laser photoastigmatic refractive keratectomy led to the
conclusion “Photoastigmatic keratectomy was partially effective in
eyes with mild stable keratoconus. However, the long-term results may
be altered by progression of corneal thinning and ecstatic disease.”
This was based on the observation that while visual activity was
improved in 7/8 eyes, in one eye there was no improvement and corneal
topography showed a progression of the keratoconus.
Journal of Cataract and Refractive Surgery, 1998, Volume 24, pages
1581-1588
Three year results of photoastigmatic refractive keratectomy for mild
and atypical keratoconus.
Kremer I, Shochot Y, Kaplan A, Blumenthal M.
Abstract at: http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=9850894&dopt=Abstract
A 1999 study concluded that LASIK and photorefractive keratectomy can
be useful in the treatment of patients with keratoconus and defined
criteria for the treatment: “Excimer laser ablation should be
performed only when the cornea surrounding the conus is flat, so that
it can join the ablated zone (small optical zone) forming a new flat
shape, without regression.”
Journal of Refractive Surgery, 1999, Volume 15 (2nd Supplement), pages
S240-S242
Treatment of keratoconus with laser in situ keratomileusis,
photorefractive keratectomy, and radial keratotomy.
Appiotti A, Gualdi M.
Abstract at http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=10202732&dopt=Abstract
A study pubished in 2000 of 27 eyes in 19 patients, who had
experienced severe complications following LASIK or photorefractive
keratectomy found that “Four eyes in two patients with possible forme
fruste keratoconus showed worsening irregular astigmatism.”
Ophthalmology, 2000, Volume 107, pages 640-652
Avoiding serious corneal complications of laser assisted in situ
keratomileusis and photorefractive keratectomy.
Holland SP, Srivannaboon S, Reinstein DZ.
Abstract at http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=10768325&dopt=Abstract
Another study published in 2000 outlines that the reason why LASIK and
similar procedures can be contraindicated in keratoconus is because
corneal thinning disorders weaken the mechanical strength of affected
corneas, which would make them less resistant to damage. The authors
describe the case of one patient who after LASIK and photorefractive
keratectomy procedures experienced the following: “After these
surgeries, a dramatic corneal ectasia and grade III haze occurred in
both eyes, with a clinical diagnosis of keratoconus. The changes in
his corneas were followed with videokeratography and slit-lamp
microscopy… Preoperative videokeratograph of both eyes suggested
keratoconus. After multiple refractive procedures, the best
spectacle-corrected visual acuity was as low as 20/1200 bilaterally.
Both eyes displayed dramatic corneal protrusion with corneal
scarring.”
Journal of Refractive Surgery, 2000, Volume16, pages 368-370
Keratectasia induced by laser in situ keratomileusis in keratoconus.
Schmitt-Bernard CF, Lesage C, Arnaud B.
Abstract at http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=10832988&dopt=Abstract
Corneal ectasia was also reported in 13 eyes with low grade myopia
treated with LASIK, of which two eyes in 1 patient and 1 eye in a
second patient had latent keratoconus before surgery. The authors
concluded “Laser in situ keratomileusis can cause permanent weakening
and ectasia of the cornea even in eyes with low myopia.”
Journal of Cataract and Refractive Surgery, 2000, Volume 26, pages
967-977
Iatrogenic keratectasia after laser in situ keratomileusis for less
than -4.0 to -7.0 diopters of myopia.
Amoils SP, Deist MB, Gous P, Amoils PM.
Abstract at http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=10946186&dopt=Abstract
Another case of corneal ectasia in a patient with preoperative
keratoconus or forme furste keratoconus is reported in:
Journal of Cataract and Refractive Surgery, 2001, Volume 27, pages
1119-1123
Contact lens fitting in a patient with keratectasia after laser in
situ keratomileusis.
Eggink FA, Beekhuis WH.
Abstract at: http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=11489586&dopt=Abstract
In a study of the long-term effects (4 years) of photorefractive
keratectomy in in keratoconus suspects, whose condition had been
stable for at least one year, there was improvement in visual acuity
and “There were no wound healing problems or any sign that the excimer
laser adversely affected the cornea during follow-up” The authors
conclude “Photorefractive keratectomy seems to be a safe procedure for
reducing or eliminating myopia or astigmatism in keratoconus suspect
eyes-most probably forme fruste keratoconus-with a stable refraction,
but this may be different in eyes with early keratoconus, known to be
a progressive disease.”
Journal of Refractive Surgery, 2000, Volume16, pages 438-443
Results of photorefractive keratectomy in keratoconus suspects at 4
years.
Bilgihan K, Ozdek SC, Konuk O, Akata F, Hasanreisoglu B.
Abstract at http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=10939723&dopt=Abstract
However, severe keratoconus developed in both eyes in the months
followingr LASIK in a patient with forme fruste keratoconus before
surgery, leading the authors to conclude conclude that forme fruste
keratoconus is a contraindication to LASIK.
Journal of Cataract and Refractive Surgery, 2001, Volume 27, pages
1115-1118
Bilateral severe keratoconus after laser in situ keratomileusis in a
patient with forme fruste keratoconus
Lafond G, Bazin R, Lajoie C.
Abstract at http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=11489585&dopt=Abstract
A 2001 article emphasises the importance of the wound healing process
on the outcome of procedures such as LASIK and photorefractive
keratectomy, and suggests that individual differences will account for
the difficulties in predicting outcome. One of the earliest events in
this process is the apoptosis (programmed cell death) of corneal
cells. They refer to recent data which indicates that perturbations in
the balance between apoptosis and mitosis (cell division and
replication) could be one of the factors leading to keratoconus in
some patients.
Archives of Ophthalmology, 2001, Volume 119, pages 889-896
The wound healing response after laser in situ keratomileusis and
photorefractive keratectomy: elusive control of biological variability
and effect on custom laser vision correction.
Wilson SE, Mohan RR, Hong JW, Lee JS, Choi R, Mohan RR.
Abstract at http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=11405841&dopt=Abstract
If such a defective balance can cause keratoconus after surgery, it is
also reasonable to assume that the defect will already be present in
keratoconus patients before surgery and therefore affect the process
of wound healing after surgery.
A 2001 article reports progressive keratolysis (destruction of the
corneal epithelium) following laser keratectomy in a patient with
keratoconus, which required a corneal graft. The authors conclude:
“Excimer laser phototherapeutic keratectomy has been shown to be an
effective treatment for subepithelial nodules in patients with
keratoconus. Rapidly progressive keratolysis is a potential
complication of this procedure.”
Journal of Refractive Surgery, 2001, Volume 17, pages 555-558
Keratolysis following excimer laser phototherapeutic keratectomy in a
patient with keratoconus.
Lahners WJ, Russell B, Grossniklaus HE, Stulting RD.
Abstract at http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=11583226&dopt=Abstract
A paper from 1999 by Buzard KA, Tuengler A, Febbraro JL reports a
study of 16 eyes with mild/moderate stable keratoconus. The authors
concluded: “The initial visual results appear promising; but longer
term results revealed regression of the refractive outcome in some
cases. Moreover, despite improvement in the postoperative spherical
equivalent and uncorrected visual acuity in most cases, the risk of
loss of BCVA and the necessity of performing PKP [corneal
transplantation] in 3 cases lead us not to consider LASIK as a primary
solution for keratoconus.”
Journal of Cataract and Refractive Surgery, 1999, Volume 25, pages
1600-1609
Treatment of mild to moderate keratoconus with laser in situ
keratomileusis.
Buzard KA, Tuengler A, Febbraro JL.
Abstract at http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=10609203&dopt=Abstract
A very recent article, published in February 2003, compared several
groups of patients who had received LASIK, in order to define risk
factors for the procedure and factors predictive of outcome. These
included 43 cases in which ectasia had developed after LASIK, 100
patients with no complications after LASIK (control group 1), and 100
patients with high myopia (high myopia in itself is considered to be a
risk factor) and no complications after LASIK (control group 2). Of
the cases of postoperative ectasia, 88% had met criteria for forme
fruste keratoconus before surgery, compared with only 2% of control
group 1 and 4% of control group 2. While ectasia is usually considered
to be a rare complication of LASIK, this study clearly shows it to
happen very often in patients with keratoconus.
Ophthalmology, 2003, Volume 110, pages 267-275
Risk factors and prognosis for corneal ectasia after LASIK.
Randleman JB, Russell B, Ward MA, Thompson KP, Stulting RD.
Abstract at: http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=12578766&dopt=Abstract
On the other hand, an Italian eye surgeon, writing in an online
ophthalmological forum, claims to have used LASIK successfully in the
treatment of keratoconus, with no occurrence of ectasia in eight
years.
A Conservative Refractive Treatment For Keratoconus Using Sector RK ,
PRK OR LASIK (follow-up 8 years)
Dr. Angelo Appiotti
Online Clinical Communications for Ophthalmologists, December 18,
2000.
Full text (and link to a pdf download) at
http://www.occojournal.com/forum/forum0003/
The 1997 Buzard and Fundingsland article has received a total of 7
citations since it was publised, according to the Science Citation
Index. One of these is the 1999 article by Buzard KA, Tuengler A,
Febbraro JL already described above.
NB The Science Citation Index is available online as SciSearch through
institutional subscription, or from Dialog Open Access, where
individual searches can be paid by credit card
http://www.dialog.com/products/openaccess/
Early clinical experience using custom excimer laser ablations to
treat irregular astigmatism
Fernandez GET, Serrano MG
Journal Of Cataract And Refractive Surgery, 2000, Volume 26, pages:
1442-1450
These authors found that 2/2 patients treated for keratoconus had
persistent less than or equal to grade 1 haze as the only
complication, and consider the results of the technique to be
promising,
None of the other citing papers include a discussion of keratoconus.
I hope that this answers your query to your satisfaction, but please
do not hesistate to request further clarification if required. |
Clarification of Answer by
tehuti-ga
on
19 May 2003 06:53 PDT
Hello again 28837,
I have found some general information on implantable contact lenses,
results obtained and contraindications. With respect to their use
after corneal transplantation, I was only able to find one study,
which relate to correction of post-transplantation astigmatism, and
one in which implantation was combined with a transplant to correct
astigmatism following keratotomy.
Implantable contact lenses, also known as “phakic intraocular lenses
(IOLs)” are still in clinical trials prior to receiving FDA approval
for use in the US, according to information on EyeMDlink.com, a web
site written by board-certified ophthalmologists for eye care
consumers. The article on EyeMDlink.com concludes: “The phakic IOL
must be shown to be as accurate in correcting refractive errors as
other refractive procedures (e.g., LASIK, PRK, Intacs) and have a
comparable safety profile prior to FDA approval. At present, data
regarding the potential risks, such as cataract formation, corneal
decompensation, and glaucoma, is being gathered. Ophthalmologist
investigators believe that the phakic IOL may prove to be a powerful
addition to the present refractive armamentarium, especially for those
individuals whose refractive errors presently fall out of the range
for LASIK.” http://www.eyemdlink.com/EyeProcedure.asp?EyeProcedureID=12
According to a news release dated June 11, 2002, from Stanford Eye
Laser Center, California, the lenses are in phase III trials, ie the
last stage before being released for wider use. There are 15 sites in
the US that are participating in this trial, with Stanford being one.
“In a procedure similar to cataract surgery, physicians implant the
phakic refractive lens behind the iris of the eye. Unlike previously
studied implantable lenses that clip onto the front of the eye, the
new lens is foldable, allowing surgeons to make a very small incision
in the cornea and slip the folded lens into place. The 10- to
20-minute operation requires no sutures.” The lens is apparently well
tolerated by the eye, and European trials have shown that most
recipients have 20/40 or better vision after surgery. The possible
downsides: “The implantable lens is hydrophobic, meaning it repels
water. Once in, it is designed to float over the natural lens of the
eye. What remains unclear, however, is whether the lens will stay
suspended and not touch the patient’s lens. If this happens, Manche
said it may result in the formation of a cataract. To date, this
complication has not occurred. The main concern with implantable
contact lenses is the risk of infection, a potentially serious
condition that can lead to loss of vision. To limit the risk, Manche
performs the surgery, which requires an intra-ocular incision, in a
sterile operating room at Stanford Hospital. In the approximately
2,000 patients who have received these lenses in earlier phases of the
clinical trials, no patient has experienced an infection, he noted.
Other possible side effects include halos and glare, and cloudy or
swollen corneas.”
At the time of the news release, Stanford was recruiting volunteers
for the trial, however patients with previous eye surgery were
excluded for participating:
“Individuals with moderate to extreme nearsightedness, between —8 and
—25 diopters on their eyeglass prescription, are needed to participate
in the trials at Stanford. Potential candidates can have up to 2.5
diopters of astigmatism. Patients must be between the ages of 18 and
50, and cannot have had previous eye surgeries. The procedure normally
costs $3,500 per eye. However, the trial is partially supported by the
manufacturer, so the cost is reduced to $500 per eye. The procedure is
done on one eye at a time, with a minimum of three months between
procedures”
http://mednews.stanford.edu/news_releases_html/2002/junreleases/lens_implant.html
The link given for enquiries is
http://www.med.stanford.edu/school/eye/laser/index.html. (This takes
you to the Eye Laser Centre web site. I could not find any further
details about the trial there. The contact information is email
eyelaser@med.stanford.edu or tel: (650) 498-7020)
Another trial centre, the Minnesota Eye Center has a detailed and
illustrated description of the procedure at:
http://www.mn-eye.com/research-artisaniol.html
Information from MidWest Eye Care, Nebraska, is that implantable
lenses have been available in other countries since 1996. The comment
is made, “In addition, the ICL may be more predictable than LASIK in
correcting high myopia, and ICL may be the first option for patients
with myopia greater than –15 diopters. Skeptics of ICL technology
worry that the ICL’s placement just in front of the natural lens will
lead to premature cataract development and/or may induce glaucoma. In
addition, patients are at risk of developing intraocular infections
with both ICL and cataract surgery, and LASIK proponents believe this
infection risk is minimized with LASIK.” The estimate is that this
procedure is at least one year away from FDA approval. Looking at the
source code for this web page, I found that this article was written
on 17 September, 2002.
http://www.midwesteyecare.com/talkinghealth/owhq&a64.htm
Going into the Medline database, I found the following information
about phakic intraocular lenses (IOL) (the URLs are for the
summaries):
In a study of 20 eyes, the authors concluded: “Posterior chamber
phakic IOL implantation for the surgical correction of high myopia is
a safe procedure with regard to immediate visual and refractive
results. The short-term clinical benefit and lack of immediate
surgical complications are impressive. However, the increase in flare,
the endothelial cell loss, the decrease in crystalline lens
transmittance, and the iris-PCPIOL and crystalline lens-PCPIOL contact
are findings that suggest caution regarding the long-term safety of
this lens implant.”
Ophthalmology 2001 Jan;108(1):90-9 Safety of posterior chamber phakic
intraocular lenses for the correction of high myopia: anterior segment
changes after posterior chamber phakic intraocular lens implantation.
Jimenez-Alfaro I, Benitez del Castillo JM, Garcia-Feijoo J, Gil de
Bernabe JG, Serrano de La Iglesia JM.
http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=11150270&dopt=Abstract
A study, which compared the use of two different types of lens in 24
eyes found: “Spectacle-corrected and uncorrected visual acuity
improved in all eyes in both groups” With respect to complications,
“The difference in mean intraocular pressure before surgery and at
last follow-up was 1.5 mmHg for the Staar group and 2.3 mmHg for the
Adatomed group… The incidence of lens pigment deposits was the same in
both groups (41.66%), with deposits in 5 of the 12 eyes in both
groups. The incidence of lens decentration was higher in the Adatomed
group (5/12; 41.66%) than in the Staar group (2/12; 16.7%). Anterior
subcapsular cataract was higher in the Adatomed group (4/12; 33.3%)
than in the Staar group (3/12; 25%).”
Journal of Refractive Surgery, 2001 Jan-Feb;17(1):32-42
Posterior chamber phakic intraocular lenses to correct high myopia: a
comparative study between Staar and Adatomed models.
Menezo JL, Peris-Martinez C, Cisneros A, Martinez-Costa R.
http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=11201775&dopt=Abstract
A comparison has been done between the efficacy of LASIK and
implantable lenses, with patients receiving one treatment in one eye
and the other in the other eye:
“To compare refractive performance and safety of laser in situ
keratomileusis (LASIK) and Artisan phakic intraocular lens (PIOL)…
twenty-five patients with myopia ranging from -8.00 to -12.00
diopters… One year after surgery, the mean spherical equivalent
refraction was -0.74 +/- 0.67 D for LASIK-treated eyes and -0.95 +/-
0.45 D for Artisan-treated eyes, and the majority of LASIK-treated
eyes (64%) and Artisan-treated eyes (60%) were within +/-1.00 D of the
intended result…. LASIK and Artisan phakic intraocular lenses seemed
to produce a similar predictability. The best-corrected visual acuity
and subjective evaluation of quality of vision were better for
Artisan.”
Ophthalmology 2002 Sep;109(9):1622-30
A randomized paired eye comparison of two techniques for treating
moderately high myopia: LASIK and artisan phakic lens.
Malecaze FJ, Hulin H, Bierer P, Fournie P, Grandjean H, Thalamas C,
Guell JL.
http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=12208708&dopt=Abstract
In January 2003, a report was published on a European multicenter
study of the Artisan lenses mentioned above. “Seventy eyes of 53
patients (mean, 35 years; range, 22-59 years) with preoperative
spherical equivalent between +6.50 and -21.25 diopters (D) and
cylinder between 1.50 and 7.25 D…. main parameters assessed were best
spectacle-corrected visual acuity (BSCVA), uncorrected visual acuity
(UCVA), refraction, endothelial cell count (ECC), intraocular
pressure, slit-lamp biomicroscopy, indirect ophthalmoscopy, subjective
complaints, and patient satisfaction… o eyes in either group
experienced a loss in BSCVA, and 46 eyes gained 1 or more lines of
their preoperative BSCVA. In 62 eyes (88.6%), UCVA was 20/40 or
better. There was a significant reduction in spherical errors and
astigmatism in all cases after surgery. All eyes of both groups were
within +/-1.00 D of target refraction, and 51 eyes (72.9%) were within
+/-0.50 D of target refraction. There was a 4.5% mean total loss of
ECC during the first 6 months. No serious complications were observed.
Overall patient satisfaction was very high.”
Ophthalmology 2003 Jan;110(1):150-62
Toric phakic intraocular lens: European multicenter study.
Dick HB, Alio J, Bianchetti M, Budo C, Christiaans BJ, El-Danasoury
MA, Guell JL, Krumeich J, Landesz M, Loureiro F, Luyten GP, Marinho A,
Rahhal MS, Schwenn O, Spirig R, Thomann U, Venter J.
http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=12511361&dopt=Abstract
Two reports from the US trials:
“Data were collected from … 65 myopes-mean preoperative spherical
equivalent, -8.42 D, who were implanted with ICLs in our clinic, from
November 1998 to March 2000… Postoperatively, 52.31% of the myopic
eyes were 20/20 or better without correction and 92.3% of the eyes
were 20/40 or better without correction, with a mean spherical
equivalent of -0.31 D…. The STAAR Collamer ICL is a reasonably safe
and effective procedure for the treatment of moderate-to-high
refractive errors.”
Optometry 2002 Jul;73(7):435-46
Posterior chamber phakic intraocular lens for moderate myopia and
hyperopia.
Bloomenstein MR, Dulaney DD, Barnet RW, Perkins SA.
Barnet Dulaney Perkins Eye Center, Phoenix, Arizona 85016, USA.
http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=12365662&dopt=Abstract
“One hundred fifty-five eyes of 155 patients with myopia from -5.5 to
-22.5 diopters (D) underwent implantation of an Artisan lens… At 6
months, 85% of eyes saw 20/40 or better uncorrected, and 90% of eyes
were within 1 D of the attempted correction. Refractive astigmatism
increased in 4.8% of eyes and decreased in 17% of eyes at 6 months. At
2 months, six eyes (4.8%) lost two or more lines of best
spectacle-corrected visual acuity; by 6 months, no eyes lost two or
more lines of best-corrected visual acuity. Endothelial cell count was
unchanged at 6 months compared with the preoperative count.
Nonprogressive lens opacities developed in four eyes as a result of
surgical trauma. Chronic inflammation was not detected in any eye by
slit-lamp biomicroscopy, nor did any eye develop angle closure or
glaucoma. CONCLUSIONS: Short-term results suggest that the Artisan
lens is an accurate and safe method for the correction of high myopia.
Surgical skill is important in avoiding lens opacities. Longer-term
data are needed to assess the impact of the lens on the endothelium,
the crystalline lens, and the iris.”
Ophthalmology 2002 Sep;109(9):1631-41
Artisan phakic intraocular lens for myopia:short-term results of a
prospective, multicenter study.
Maloney RK, Nguyen LH, John ME.
http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=12208709&dopt=Abstract
Cell loss has, however, been found to occur in some cases after the
procedure, but this does not seem to present any long-term
difficulties:
“Continuous endothelial cell loss was observed after ICL implantation
during a 4-year follow-up. There was rapid cell loss until 1 year
postoperatively, after which the rate of loss was no longer
statistically significant. The percentage of hexagonal cells
(polymorphism) and the coefficient of variation (polymegethism)
remained stable during the 4-year follow-up.”
J Cataract Refract Surg 2002 Sep;28(9):1589-93
Long-term endothelial changes in phakic eyes with posterior chamber
intraocular lenses.
Dejaco-Ruhswurm I, Scholz U, Pieh S, Hanselmayer G, Lackner B, Italon
C, Ploner M, Skorpik C.
http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=12231317&dopt=Abstract
Opacification of the lens, due to tissue growth over it, is one
possible complication:
“To describe a case series to determine the incidence of lens
opacities after posterior chamber phakic intraocular lens (IOL)
implantation (STAAR Surgical, Monrovia, CA) for very high ametropias….
Fourteen eyes of 170 consecutive eyes with high ametropias in whom
lens opacities developed after posterior chamber phakic IOL implant…
In the entire series, 5 of 170 (2.3%) implantations had symptomatic
opacities in which 111 implantations were the first or second case of
the implanting surgeon. CONCLUSIONS: Lens opacities are a potential
complication of phakic IOL implantation. Most lens opacities were
first seen in the early postoperative period and were most likely due
to surgically induced trauma. The anterior subcapsular type was most
common and tended not to be rapidly progressive during the follow-up
period. The presence of nuclear sclerotic cataract was visually
significant and progressive. Long-term follow-up is warranted to
evaluate the rate of progression and course of lens opacities after
phakic IOL implant surgery.
Ophthalmology 2003 Apr;110(4):781-5
Lens opacities after posterior chamber phakic intraocular lens
implantation.
Sanchez-Galeana CA, Smith RJ, Sanders DR, Rodriguez FX, Litwak S,
Montes M, Chayet AS.
http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=12689902&dopt=Abstract
Choroidal neovascularization (CNV) [abnormal growth of new blood
vessels within the eye] is another possible late complication. In a
study of 294 eyes in 181 patients followed up for 6-120 months,
“Choroidal neovascularization occurred in 5 eyes (1.70%); 3 eyes were
in women, and 2 were in men. The interval between PACL implantation
and CNV was 63.2 +/- 27.3 months (range 18 to 87 months)…. The mean
best spectacle-corrected visual acuity (BSCVA) after PACL implantation
and before the appearance of CNV was 0.53 +/- 0.18 (range 0.4 [20/50]
to 0.8 [20/25]); after CNV appeared, it was 0.26 +/- 0.18 (range 0.05
[20/400] to 0.5 [20/40]),… Implantation of a PACL to correct high
myopia was followed by a small incidence of CNV (cumulative risk of
5.4% at 87 months). The appearance of CNV was followed by a
significant decrease in BSCVA.”
J Cataract Refract Surg 2003 Feb;29(2):270-4
Choroidal neovascularization in phakic eyes with anterior chamber
intraocular lenses to correct high myopia.
Ruiz-Moreno JM, de la Vega C, Ruiz-Moreno O, Alio JL.
http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=12648636&dopt=Abstract
Another reported complication in one patient:
“A 23-year-old woman with -14.00 diopters of myopia… ICM 130 V2 myopic
phakic intraocular lens (IOL) (Staar Surgical AG) was implanted in the
posterior chamber. Three days later, the patient developed malignant
glaucoma…. As maximum medical treatment failed, rapid secondary
surgery was performed with sclerotomy, aspiration in the midvitreous
cavity, and removal of the IOL. The follow-up was 43 months.”
J Cataract Refract Surg 2002 Dec;28(12):2217-21
Malignant glaucoma induced by a phakic posterior chamber intraocular
lens for myopia.
Kodjikian L, Gain P, Donate D, Rouberol F, Burillon C.
http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=12498863&dopt=Abstract
Night vision can be affected:
“Although daytime vision is usually very good some patients complain
of visual disturbances, described as glare and halos, during the night
time, leading to difficulties in driving vehicles…. The quality of
vision after phakic IOL surgery was investigated pre- and
postoperatively using various tests for objective measurements of
glare and halo in 40 myopic eyes (-9.0 to -20.0 D)…. All patients were
happy with the postoperative refractive outcome and during daytime no
visual discomfort was reported. In contrast, most patients reported
visual disturbances during dim light conditions and at night time,
described as glare and halos…. All currently available phakic IOLs, in
particular the ICL and the NuVita lead to a decreased visual
performance during night time. Therefore, this phenomenon must be
explained to the patient prior to surgery. An increase in the size of
the optic should lead to an improvement with reduction of
postoperative glare and halos.”
Ophthalmologe 2001 Nov;98(11):1055-9
[Glare and halos after "phakic IOL". Surgery for the correction of
high myopia]
[Article in German]
Maroccos R, Vaz F, Marinho A, Guell J, Lohmann CP.
http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=11729736&dopt=Abstract
Specifically with respect to corneal transplantation (keratoplasty), I
have found the following studies in which phakic intraocular lenses
were used after, or in combination with, keratoplasty:
“Visual outcome after penetrating keratoplasty is often Iimited by
residual astigmatism…. The implantation of an ARTISAN toric
intraocular lens presents an additive option to correct corneal
astigmatism in phakic eyes. This toric intraocular lens (IOL) has an
optical zone of 5.0 mm with a sphericaI front and a toric back. The
torus of the IOL is available up to 7 D in half dioper steps… A
27-year old female presented with a bestcorrected visual acuity of
20/32. Penetrating keratoplasty was performed in 1997 because of a
decompensated keratoconus. Despite a clear allgraft visual acuity was
limited because of a keratoplasty-related high astigmatism of 7.6
D/124 degrees, which could not be sucessfully treated with glasses or
contact lenses. An ARTISAN toric intraocular lens with - 3 D spherical
and 7.0 D/0 degrees cylindrical power (individually manufactured) was
implanted… After 3 months uncorrected visual acuity was 20/25. Six
months after implantation the IOL was still well-centered and
uncorrected visual acuity was 20/20. CONCLUSION: Implantation of an
ARTISAN toric intraocular lens in phakic eyes is an alternative and
new option to correct higher astigmatism. In contrast to the
keratorefractive option minor manipulation on the allograft can be
expected. For a final conclusion of the endothelial cell loss longer
follow-up is necessary.”
Klin Monatsbl Augenheilkd 2002 Mar;219(3):159-63
[Implantation of an ARTISANtrade mark toric phakic intraocular lens to
correct high astigmatism after penetrating keratoplasty]
[Article in German]
Tehrani M, Dick HB.
http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=11987045&dopt=Abstract
“A case of secondary hyperopic astigmatism (+0.75 +1.50 x 45 degrees)
is reported in a patient who had undergone radial keratotomy for
myopia of -6.00 +0.75 x 90 degrees, 8 years previously. Preoperative
uncorrected visual acuity was 20/120 improving to 20/20 with
correction. Further refractive procedures were performed including
arcuate keratotomy, posterior chamber phakic intraocular lens
implantation and laser thermal keratoplasty to improve the uncorrected
visual result. RESULTS: Final uncorrected visual acuity was 20/40,
spectacle-corrected visual acuity was 20/20 with a manifest refraction
of +0.50 +1.00 x 40 degrees.”
J Refract Surg 1999 Nov-Dec;15(6):683-6
Overcorrected radial keratotomy treated with posterior chamber phakic
intraocular lens and laser thermal keratoplasty.
Fink AM, Gore C, Rosen ES.
http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=10590008&dopt=Abstract
Contraindications:
I found one paper available on the Web in full text which lists some
contraindications for implantable contact lenses:
“corneal degenerations and dystrophies, evidence of lens opacity or
developing cataract, pseudoexfoliation, pigment dispersion, glaucoma,
history of uveitis, macular pathology, or retinal detachment”
Journal of Refractive Surgery Volume 17 November/December 2001,
641-645,
Contrast Sensitivity After Posterior Chamber Phakic Intraocular Lens
Implantation for High Myopia
Ignacio Jiménez-Alfaro, MD; Germán Gómez-Tellería, MD; José Luis
Bueno, MD; Pilar Puy, MD
http://jrs.slackinc.com/vol176/alf.pdf
If the above URL does not work for you, the article is present in
Google’s cache at
http://216.239.37.100/search?q=cache:Uzfo1vFt1XEJ:jrs.slackinc.com/vol176/alf.pdf
The product literature for the Artisan lenses featured in some of the
studies lists the following contraindications:
Endothelium cell counts less than 2000 cells/mm2, Anterior Chamber
depth less than 2.6 mm, Acute inflammation, Glaucoma or family
history of glaucoma, Intraocular pressure > 21 mm Hg, Retinal
detachment or family history of retinal detachment, Any form of
cataract, Recurrent or chronic iritis, Chronic or recurrent uveitis,
Pre-existing macular degeneration, retinopathy, Fixed pupil size > 4.5
mm, Abnormal iris, Abnormal pupil, Abnormal cornea, Surgical
difficulty at the time of surgery, which might increase the potential
for complication, Patients under 18 years of age
Search strategy: On Google: “implantable contact lenses” “phakic
intraocular lenses”
On Medline: 1. “phakic intraocular” keratoplasty
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