From: Leo.Bores@f14.n114.z1.fidonet.org (Leo Bores)
Subject: RK questions
In an article of <16 Jan 90 04:19:41 GMT>, joshua@athertn.Atherton.COM (Flame
Firstly - the correct name is RADIAL keratotomy, an apt name (which, incidently
I coined) which describes the incision pattern.
FB> 1. Is it safe?
Properly performed by a well trained physician - it is safe and permanent.
FB> 2. Does it work?
In cases whose myopia is below -6.00 diopters, the mean for resultant vision of
20/40 or better is 89%.
FB> 3. Is it permanent?
Yes - which can sometimes be a problem if you get too much correction - there
is no eraser on a knife.
FB> 4. How would you choose an RK doctor. My normal eye doctor does
FB> not do or recommend this procedure, so I doubt I could ask for
FB> references from him.
Typically optometrists (who are neither MDs nor surgeons) decry this surgery as
dangerous an ineffective despite strong evidence to the contrary and despite
the fact that the American Academy of Ophthalmology has recently endorsed it.
While there are complications and side-effects from the surgery (as there are
in ANY surgical procedure) in the main the benefits outweigh the risks. Most
detractors who describe "horrible" consequences rely on 13 (out of 300,000+)
cases reported by Dr. D. O'Day of which 56% had nothing to do with the surgery
FB> 5. What questions should I ask, to try to get a feel for how good
FB> an RK doctor is?
How many surgeries has he performed of the type necessary in your case. If
none - what makes him confident that he can succeed in your case? From whom
did he get his training for the operation? If from a medical school - forget it
unless it was UC San Diego. The best teachers are Prof. Fyodorov (USSR),
myself (Phoenix), A. Neuman (Orlando), F. Kremer (Philadelphia), P. Arrowsmith
FB> 5. Does anyone have any good or bad experiences with any
FB> RK doctors in the SF/SJ Bay Area?
Dr. George Simon does good work up there.
FB> 6. Has anyone heard of either of these places:
FB> San Francisco Eye Institute
FB> King Medical Center (San Jose)
Name the doctors there.
Leo Bores, M.D. - American father of RK (and undoubtedly biased)
From: Leo.Bores@f14.n114.z1.fidonet.org (Leo Bores)
Subject: Re: RK questions
In an article of <18 Jan 90 17:35:44 GMT>, rlt@cbnewsl.ATT.COM (r.l.taylor)
rA>What about patients with astigmatism? I went to one opthamologist who
rA>would make me a bad candidate for the surgery.
Actually, it probably makes you a better candidate for the surgery. The chap
you consulted may not be very experienced with the procedure.
rA>I asked one opthalmologist how many he'd done, and his answer was "I
rA>answer questions like that." That ruled him out for me. (This was the
rA>guy who made the statement about astigmatism. When he wouldn't even
rA>my questions, I kind of lost confidence in his ability to evaluate my
rA>How about Northern NJ? Can anyone recommend someone up here?
rA>Any recommendations would be greatly appreciated.
Dr. Hal Waldman - in Hackenscak is the man.
rA>Sounds like you can afford to be biased, when you're the expert!
Some people think that does not signify. The Academy of Ophthalmology has
turned down all my requests to give a paper since 1979. Yet they accepted one
from a guy whose experience was exactly 20 cases and six months. Seems that I
stepped on some sacred toes somewhere. They've refused Fyodorov too - so i'm
in good company.
In an article of <5 Mar 90 04:08:33 GMT>, joshua@athertn.Atherton.COM (Flame
FB>I'm trying to understand the JAMA article on RK ["Results of the
FB>Prospective Evaluation of Radial Keratotomy (PERK) Study 4 Years
FB>After Surgery for Myopia" Feb. 23, 1990].
You are not alone in this. Without going into tedious detail - there are lots
of things "wrong" with the PERK study. What is remarkable is that their
results are as good as they are.
FB>I know there has been a lot of general RK discussion recently, and I do
FB>not want to rehash it, but I do have some specific questions about the
FB>1. What is the importance of 1.0 diopter? How do diopters map to
FB> numbers? The study uses 1 diopter as the border between good and
FB> in a couple of places, but I can not map diopters into anything I
FB> understand. For example, can someone who needs 1.0 correction drive
FB> safely without it? What about 2 or 3 diopters?
Diopters CANNOT be mapped into visual acuity in ANY meaningful way no more than
apples equate to oranges. 20/XX is a method that seeks to give a
quantification to the resolving power of the eye with respect to standardized
letter sizes. This method, adopted 125 years ago, is quite simple. 20/20 means
that the tested eye can discern a specific sized letter at 20 feet (6 meters) -
this is considered the norm. 20/40 means that the tested eye can discern a
letter of a size at 20 feet that a "normal" eye can discern at 40 feet, etc.
Dividing the numerator by the denominator gives you an idea of the visual
efficiency of the eye. Thus a 20/40 eye has a 50% efficiency - sufficient to
drive in all states, day or nite.
That acuity, of whatever degree, can be 20/100 if a person is nearsighted or
farsighted. Usually myopia in excess of -2 decreases the acuity to 20/100 or
less but then so does a +2, except that the -2 eye will see clearly up close.
FB>2. "Lack of predictability." The study found that the 90% predictive
FB> was 4.4 diopters. At the same time it found that 64% of the people
FB> the surgery did not need to wear glasses after it. Don't these two
FB> contradict each other? If the predictability is so low, why is the
FB> rate so high?
Because most patients see better after the surgery even though their residual
refraction would have caused less vision pre-op. There are various reasons for
this but the most likely explanation is that the individual is changing their
corneal curvature with lid pressure. Elevating the lids in these cases cause
the acuity to drop.
The most glaring problem here is the way in which the patients for the study
were grouped. They were divided into three groups the first two having one
diopter range of myopia, i.e. -2 to -2.99, -3 to -3.99. The last group was -4
to -8. Each groupd had only one optical zone size 4, 3.5,3) and eight
incisions. NO attempt was made to predict the outcome nor was the surgery
tailored individually to each patient as Fyodorov and I taught (there are 11
factors to be considered). Thus the PERK study was essentially pounding square
pegs into round holes. But hey - government sponsored study, must be good -
right? (Remember, that same group brought you VietNam and other pleasantries) -
about 10 million bucks worth of re-inventing the wheel.
FB>3. a) The requirements for the investigators included completing 10 or
FB> pilot cases. Does this mean 10 or more RK surgeries, or 10 or more
FB> surgeries using this exact protocol. How experianced were the
Not experienced at all except what I taught them and the 10 "pilot" guinea
FB> b) There does not seem to be any figures comparing the different
FB> Were these numbers published earlier?
No - while I have those figures (my spies are everywhere) - they were never
published. Suffice it to say that the one really experienced surgeon in the
group (one of my residents) had a success rate that approached 80%.
FB> c) There does not seem to be any figures comparing the people who
FB> the study early on, and those entering it later on. (This data
FB> especially interesting if the surgeons involved had only done a few
FB> before starting the study).
Yeah - they never factored that in either.
FB>4. What is the significance of the change (or drift) in the patient's
FB> In about 25% of the cases this change was greater than 1.0 diopters,
FB> measured between 6 months after RK and 4 years after RK. Do eyes
FB> normally? If so, how much?
Yes they do. The best study of this natural drift was done at Duke. That study
showed that there is a natural progression toward farsightedness in unoperated
myopes and that in a multivariate analysis of both operated and non-operated
eyes (age matched), there was no statistical significence between the two
FB>I realize that some of my questions can be answered by reading the
FB>sources, but I have having trouble getting some of them. JAMA is
FB>available, but some of the other journals are hard to get.
FB>Thanks for your help. I have one last comment:
FB>People (non-doctors) can read the PERK study and come out with very
FB>results. For me, it has almost convinced me to get the surgery. For
FB>room mate, it convinced him that he did not want RK. I think this is
FB>I tended to look at the happy vs. unhappy patients (90%/10%) and the
FB>who did not need to wear glasses (64%). My room mate tended to look at
FB>range of 90% perdictability (4.4 D), and the scatter rate in the tables
FB>pages 1085 and 1086). The change in refraction in the time 6 month to
FB>after the RK surgery made both of us uneasy.
Yes - and the newspaper accounts were askew also. The bottom line is that most
patients were happy with the surgery. As to unpredictability - that odium
applies to surgery done in the manner of the PERK - which is an artificial
construct devised to meet the needs of the study and not the patient. The ARC
study, done on 450 patients by five doctors shows significent differences in
success rate and predictability. Properly performed, the predictability
matches that of intraocular lens implantation.
All the citations with some abstracts are available on EyeNet - 602-941-3747.
Leo Bores, M.D.
In a message of <28 Feb 90 02:35:07>, Larry Kessler (1:106/12) writes:
LK>Leo, I'm somewhat myopic (contacts are -5.00 left, -0.75 right) and am
LK>Two questions: (1) Where are we at present regarding complications,
LK>suboptimal results, side effects, price, and so forth?
Complication rate is low and on a par with wearing contact lenses. Prices
vary. Everybody gets transient glare and visual fluctuation. Vision loss is
(2) Do you perform the procedure yourself?
I am the co-author of this operation and have taught most of the worlds
physicians either directly or indirectly - this operation. The short answer is
- yes I do the surgery.
Your myopia is in a range in which the greatest success lies. I'm doubtful
that the complication rate will get much less except for one thing - I'm
certain that predictability will improve. Thanks for your interest.
Leo Bores, M.D.
From: Leo.Bores@f14.n114.z1.fidonet.org (Leo Bores)
SR>I'm a little confused now --- what's the difference between
SR>and keratophakia? Is the latter another way to refer to the Barraker
Keratophakia is reserved for high hyperopia and requires the intrastromal
implantation of a tissue lenticule.
SR>BTW, one advantage of xxx-phakia is reversability (with only a little
SR>residule scarring far from the visual axis, or do I not fully
see my previous message to you.
SR>New question: How goes it with intralamellar implants?
I just talked to dan Durrie and he's very enthusiastic. I might have to modify
my jeering about ILM being the "material of the month".
SR>If anybody can overcome the problems that I have heard about with ILM
SR>that's the one for me! On paper, it's perfect! Too bad there's such a
SR>scarring problem, eh?
Yes and no. I'm still concerned about those cases wherein the implant became
encapsulated and about the loss of keratocytes over the implant. Still it's
looking better and better.
SR> SR>>I trust you were able to steer the person with the question
SR> SR>>qualified RK surgeon --- he really wants to do away with his
SR>BTW, Where are you (City, State)?
SR> I do have one patient who has a
SR>interest in RK, but I didn't know who to refer her to as nobody in my
SR>does RK and the only RK surgeons I know of in Philly are what an
SR>ophthalmologist friend of mine refers to as "slash for cash"
SR>you know the type, the ones you wish didn't share your credentials or
SR>your degree, and bring down the averages for RK in general...
I agree with your assessment altho' Kremer is an excellant surgeon.
SR>Food for thought: If RK were to graduate from experimental to accepted
SR>the FDA and one then had to get MP insurance to cover the procedure,
SR>might this effect the "slash for cash" operators? Would they stop
Firstly - the FDA does NOT signify. They have NO mandate to regulate the
acceptance or rejection of surgical procedures per se. There is NO arm of the
government that does - for better or for worse. What would happen in the event
you describe is that all those bozos would raise their prices. However, we
would hope that patients would be savvy enough to chose reputable and
experienced surgeons on merit alone - fondly to be wished!
SR> Another new question: Do you cut from limbus towards center or
I originated the technique of cutting from the INSIDE out to the limbus right
at the beginning because of the safety factor. I had to make some fundamental
changes in the procedure as a consequence that escalated domino fashion,
materially changing the surgery and emphasizing blade qulaity and leading to
ultrasonic pachymetry (first instituted by Kremer, B-T-W). However, I recognize
that, in some cases, cutting from the limbus is necessary and beneficial. So I
guess the answer is both as the circumstances warrant. I am a trained
ambidextrous person as well - just about have to be to do eye surgery.
Never let it be said that fear has no place in progress :-)
Leo Bores, M.D.
From: Leo.Bores@f14.n114.z1.fidonet.org (Leo Bores)
In a message of <16 May 90 02:49:44>, Stephen Risik Of 100/514 (1:100/514)
SR>I hope this puts things into perspective for you. For the time being,
SR>continue to wear my spectacles (OD +0.50 -3.00 x 100, OS +0.50 -2.75 x
SR>which give me 20/15 VA's in each eye and occasionally my toric contacts
SR>give me @ 20/20 vision. You see, my correction does not lend itself to
SR>very well --- an RK surgeon told me to expect VA's without an
SR>of only 20/30 or so and that there would be a good chance of winding up
SR>with irregular astigmatism which would require rigid contacts to boot.
SR>course, I was consulting one of the good surgeons who gave me a
SR>prognosis rather than a "slash for cash" type who always paints a rosey
Hmmm.. I'm not sure I agree with your ophthalmologist Steve. As a pure myopic
astigmat, two symetrical 2.5 mm "T" cuts would be morelikely to reduce your
astigmatism than produce more - particularily of the irregular variety. I
wonder if he (she?) speaks from personal experience or hearsay? On the other
hand - you are enjoying excellant corrected VA as it is and are not motivated
That's really the bottom line. If an individual has good and sufficient reason
for wanting the surgery and has both a realistic attitude as well as is
informed of the risk-benefit ratio - then by all means go for it. I, for one,
do not "sell" the surgery. Patients seek me out for it - not vice-versa. I may
make less money that way but I sleep nites even tho' I might lose a patient to
an RK "mill" by not advertising. I've stopped tilting at windmills and trying
to save people from themselves. I really have to answer only to me and the "guy
upstairs". Who was it said: "To thine own self be true, then thou canst be
false to no man"?
SR>cells (epithelium). It has the advantage of being reversable if it
SR>work out, but it takes a lot of skill and is still experimental.
Epikeratophakia is really not reversible but the tissue can be removed and
another piece applied. The reason that it is not reversible is that Bowman's
membrane is transected causing the entire corneal cuvature to change -
permanently. The problem was (is) compounded if the surgeon performing the
operation RESECTS an annulus (as was originally advocated) of tiisue in
preparation for embedding the donor disk. Clearing of the freeze-dried
lenticule (the potatoe chip) is markedly prolonged. A newer, and more
successful, way to do the surgery is to cut through Bowman's with a trephine
and undermine at 10 degrees WITHOUT tissue resection and then use a FRESH
lenticule carved on the lathe and a non-torquing suture used to haold the
lenticule in place.
Few surgeons have the lathes to do this (I guess there are about 7 or 8 of us)
however - but the results exceed the freeze-dried by several magnitudes and
clearing is rapid.
Epi is really not reccomended for myopia except in the special case of
myopia-astigmatism called "keratoconus". here it works very well indeed. It
also works well in low hyperopes. It has been advocated in pediatric aphakes
but I strongly reccomend IOLs in these cases - particularily the silicone
Leo Bores, M.D.
From: Leo.Bores@f14.n114.z1.fidonet.org (Leo Bores)
In response to the above request, I am attaching this multipart message. Since
it would take 23 pages to include it all (including bibliography) I'm only
going to post the text. If you want the whole thing - call my system and
download REFSURG.88 from the PUBLIC file area - it's 61K. On my system there
exists an area called: Medical Reference Library. here you will find references
from the literature on certain eye diseases and topics going back, in some
cases, to 1713. You are welcome to browse, DL as well as contribute.
Page 1 of article:
REFRACTIVE CORNEAL SURGERY
Refractive eye surgery is defined as that surgery upon the eye which
acts to change the light bending characteristics of that eye. This
definition would include such things as cataract surgery - with or
without the implantation of an intraocular lens. We will, however,
confine ourselves to surgery performed upon the cornea of the eye.
There are currently five methods of surgically modifying the cor-
neal curvature presently in general usage. These are: 1) -
Keratomileusis; 2) - Radial Keratotomy; 3) - Epikeratophakia; 4) -
Keratophakia; 5) - Keratoplasty. Of these five, the latter - Keratop-
lasty, does not have as its primary goal (except in cases of
Keratoconus) the modification of the corneal curvature and so will be
discussed only incidentally.
Keratomileucis, and Keratophakia are lathing procedures that had
their beginnings in 1949 with the work of J. I. Barraquer, M.D. of
Bogota, Columbia, South America. It was introduced into the United
States by Richard Troutman, M.D. professor and chairman of the
Ophthalmology department of the Manhattan Eye and Ear Infirmary. The
technique of Keratomileucis (KM) consists of the temporary removal of
a lamellar section of the patients cornea. This is done by placing a
specially constructed suction ring upon the eye after the eye (or the
patient) has been thoroughly anesthetized. This ring is designed to
fit tightly against the anterior portion of the eye allowing the en-
tire cornea to protrude through the central opening. This ring is
fitted with dove-tail guides on its front surface which serve to guide
the footplate of a device called a MICROKERATOME. When suction is
applied to the ring, it holds the eye against it tightly and causes
the pressure in the eye to increase to about 60 mm of Hg. To avoid
variations in resected tissue thickness the suction pressure is
regulated at 22 mm Hg. This causes the cornea to move foreward
slightly. A clear plastic applanation lens is placed upon the eye to
check the diameter of the tissue disk to be resected. If the disk is
too large or too small, a different ring is substituted until the size
Guided by previous experience and the effect desired, the mic-
rokeratome is prepared by inserting a special plate into the bottom
section. The thickness of this plate and to a lesser extent the pres-
sure induced by suction controls the thickness of the resected tissue.
The microkeratome is equipped with a special blade which is oscillated
at approximately 10,000 RPM and is controlled through a footswitch.
The sequence of events then is as follows: the ring is applied to
the eye and suction begun. A reference mark is scratched upon the
corneal surface with a needle. The microkeratome is irrigated and en-
gaged into the ring dovetails. It is advanced across the eye until
almost in contact with the cornea and the motor started. With a
smooth, even motion - not stopping - the microkeratome is advanced ac-
ross the cornea until the blade is clear. Suction is then stopped as
is the motor. The resected tissue disk is grasped gently with forceps
and transferred to the thickness gauge. Both the diameter of the tis-
sue and its thickness are entered into a computer program. The tissue
is then placed into a preservative solution of Kitton Green. The
patients resected bed is then scrubbed by irrigating with Balanced
Salt Solution and wiping with a Sable Brush. A plastic cap is then
placed over the bed to prevent the introduction of dust particles.
Gloves are not worn during these procedures to avoid the introduction
of talc and other particulate matter into the interface.
After 1 minute, the tissue is removed from the preservative and
its thickness re-gaged. This figure is also entered into the com-
puter. The tissue is then placed onto a pre-lathed Delrin base which
is mounted on a special lathe. The tissue is centered making sure
that no air bubbles are trapped behind the disk. This is especially
critical in Keratophakia (KP). Recently, a balloon of thin rubber
(made from a condom), has been used to insure absolute contact with
the Delrin base. The lathe is then adjusted up to speed and its sett-
ings modified according to the computer read-out. The gas (CO2) is
turned on and freezing begins.
When the tissue and cutting tool have been frozen, the tool is ad-
vanced and the disk re-shaped by cutting away excess corneal tissue.
Preset stops control the amount of tissue resected. The gas and lathe
are turned off and the carved lenticle along with its based is allowed
to thaw. Recently this thawing has been accomplished by plunging the
tissue-base into a solution kept at 37x C. Using a perforated spoon
designed for this purpose, the lenticle is transferred to the patients
eye and gently dropped into place. The tissue is aligned with the
reference mark and secured with 2 to 3 10-0 Nylon "cardinal sutures".
The lenticle is sutured in place using running 10-0 nylon suture
placed in a special 8-sided, non-torquing pattern. The cardinals are
removed and the running suture adjusted until the lenticle is per-
fectly centered. The knot is then tied using a 3-2-2 throw and the
suture ends cut short.
An injection of subconjunctival steroids and anti-biotics follows
along with a drop of anhydrous glycerine. The eye is then patched
with two cotton patches and a perforated aluminum plate called a Fox
Shield is taped over the patches. Some physicians will also suture
the lids closed before patching. The patient is then awakened from
anesthesia and taken to the recovery room.
Post operative management consists of monitoring the progress of
the healing and staying alert for signs of infection - which is very
rare. Post-operative pain is remarkably little owing to the fact that
the corneal nerves have been transected. The use of
steroid/antibiotic drops aids the post-operative recovery by alleviat-
ing tissue reaction. The use of anhydrous glycerine drops applied
three times daily seems to accelerate the loss of edema in the len-
ticle and speeds visual recovery in these cases. The sutures are
generally removed after 2 weeks where the patients own tissue has been
used and at 3 weeks in cases of donor tissue being used or in cases of
Generally speaking, recovery of useful vision occurs at about 2 to
3 weeks. However, it is not unusual for the process to take as long
as 4 months particularly in cases of high myopia where the lenticle
has been made quite thin. Once useful vision has been obtained
scheduling of the second eye can take place.
The complications of this surgery are those that can be expected
of any non-penetrating surgical procedure. Infection is usually rare
and confined to the corneal stroma and is generally localized. It
responds well to topical antibiotics but some may require sub-tenons
injection. Cases of severe intraocular infection have been reported
with a few cases of endophthamitis leading to visual loss having oc-
curred. Induced astigmatism is by far the most common complication
occurring with this surgery and occurs in about 4% of the cases tend-
ing to group in the higher myopia ranges. Occasionally, epithelial
cells will be introduced into the interface during this surgery.
These cells can proliferate to the point of producing large plaques or
sub-lenticular fluid. In these cases the lenticle has to be removed,
cleaned, and replaced - suturing it back into place. Re-
epithelialzation is generally rapid after this surgery. However,
rarely epithelialization may not occur. In these cases a new lenticle
must be made from donor tissue and replaces the old one. A trial of
topical cysteine drops may be warranted based on recent reports.
The success rate of this surgery within its indicated range is
high (89%) - comparing favorably with other techniques. Because of
its technical complexity the surgery is reserved for myopia cases hig-
her than 7 diopters (some doctors say 6) with a practical upper limit
of 15 diopters in autoplastic cases and 19 diopters in homoplastic
(donor tissue) cases. In low hyperopia the range is from 4 diopters
to 9 diopters. Above that the technique of Keratophakia can be used.
Astigmatism cannot be treated directly with this technique. Attempts
to produce toric lenticles have all failed due to the elasticity of
Recently, Luis Ruiz and I have perfected a method of performing
keratomileusis for myopia without freezing/lathing. Called "Kerato-
mileusis-in-situ", the operation is performed entirely on the eye.
By making two passes of the keratome across the cornea, it is possible
to completely eliminate up to 30 diopters of myopia. Recovery is much
more rapid than with the classical methodology.
Keratophakia is reserved for high hyperopia usually associated
with cataract surgery. With the advent of intraocular lense implants,
the need for this type of surgery has declined. However, it is still
indicated in those patients in whom the introduction of the IOL is
contraindicated - such as severe diabetics.
In this surgery donor tissue is used. Thick sections of fresh or
preserved corneal tissue can be used. Furthermore, tissue not
suitable for use as transplant material can be used. This is for-
tunate in that no drain is placed upon the scanty tissue supply. The
tissue needs to be dissecated a little before lathing. The lathing
procedure is similar to that of KM except that the tissue is placed
upon the base with the curved side up. Here is where the balloon
shines because of the tendency of the tissue to pull away from the
tool. The lathing is done in a similar manner and is accomplished
before the section is taken from the patient. In KP the patients disk
is larger than in KM and the thickness is determined by the amount of
refractive error. There is a tendency to adjust the thickness to make
it slightly thinner in higher cases to control the overall tissue
thickness. The lenticle is placed in the bed and the patients tissue
placed over it. Cardinal sutures are placed in 4 quadrants. A double
running non-torquing suture is placed providing 16 areas of support.
The cardinals are then removed and the eye treated as in KM.
Post-operative care is similar to that of KM except that the
sutures allowed to remain for a longer period of time. Recovery of
vision is quite slow and a number of patients will never achieve the
same level of corrected vision as preoperatively. Nonetheless, the
technique is a valuable procedure in indicated cases. Theoretically
there is no upper limit to the amount of hyperopia that one can cor-
rect with this surgery. However, the considerations of corneal
physiology and anatomy set an upper limit of 22 diopters to this sur-
Within the last few years, several techniques have been put forward
to correct hyperopia or farsightedness. The hexagonal procedure,
championed by Mendez has been shown to be effective in up to 6 diopters
of plus correction but is fraught with difficulties both for the
physician and the patient. It is probably best reserved for cases with
corrections of 2 diopters or less. The procedure is performed by marking
an centered hexagon upon the corneal surface and making connecting
incisions along the marks - no greater than 80% of the corneal thickness.
Gaping and instability of the central cornea are the biggest problems
associated with it's use.
The second method, advocated by luis ruiz and myself, is Hyperopic
Lamellar Keratotomy. In this procedure, a predetermined diameter disk
of corneal of approximately 80% thickness is resected using the micro-
keratome and immediately resutured to the eye. The sutures can be
removed in 10 to 15 days. An amount of relative corneal ectasis (bulging)
occurs post-operatively, proportional to the diameter of the resected
disc. This procedure is more uniform than the hexagonal procedure and
is also more predictable. In addition, the corneas are extremely stable
Attempts have been made in the past to substitute allopathic
materials for the tissue lenticle. These have met with varying de-
grees of success. Most have lead to problems of corneal decompen-
sation due to tissue starvation. The substances are of necessity non-
porous and are impermeable. They thus block the passage of vital nut-
rients from the back of the cornea to the front. There is also a ten-
dency for the formation of encapsulating membranes as the body seeks
to externalize what it sees as a foreign body.
Recently, there has been used for this purpose a special kind of
plastic developed to make windows for spacecraft and space suit facep-
lates. This material, called polysulfone, can be cast or carved and
is autoclavable. It has been implanted successfully into the corneas
of human subjects but more data is needed. In those patients in whom
it has been used the recovery has been slow and visual acuity in some
cases is less than pre-op. In animal models, examination of the tis-
sue surrounding the implant reveals a loss of keratocytes despite the
corneas remaining clear. The significence of this cell loss is
Radial Keratotomy was begun in 1973 after a chance observation of
corneal flattening after eye trauma in a child. Svyataslav N.
Fyodorov, was at that time, director of The Clinic for Experimental
Eye Surgery in Moscow, USSR. Professor Fyodorov was already well
known for his pioneering work in intra-ocular lense implant surgery.
The surgery was introduced into the United States, in 1978, by Leo D.
Bores, M.D. at the time Clinical Professor of Ophthalmology at the
Kresge Eye Institute in Detroit, Michigan.
The surgery works by causing temporary peripheral weakening of the
corneal tissue. This is accomplished by making radiating, partial
thickness incisions into the corneal stroma from the epithelial sur-
face. These incisions are varied in length, number, and depth to vary
the resultant correction.
In the beginning, this surgery was confused, possibly
deliberately, with a similar technique espoused by T. Sato, M.D. of
Japan, in 1953. The so-called Sato procedure, in which the incisions
were made from the inside or endothelial surface, led to corneal
decompensation in about 22% of the cases. In addition, certain
technical deficiencies resulted in low corrections which did not war-
rant the risk of surgery. Consequently, the surgery was abandoned.
It was subsequently discovered that the reason for the decompensation
was the destruction of the corneal endothelial pump caused by the in-
The technique is quick and relatively painless making it ideally
suited for the out-patient surgical facility. In addition, the
recovery period is relatively short and most patients return to normal
activity within hours. While seemingly easy to perform, the technique
requires careful attention to pre-operative details and nuances of
surgical technique. It is truly "microsurgery" in its strictest sense
as a few microns of incision depth can affect the outcome. The seem-
ing simplicity of the technique has led to variations or
"improvements" in the technique not bolstered by experimental evidence
or clinical experience. "Good" results have been reported with these
variations but they are not optimal as further study has revealed.
The patient is given a mild sedative prior to surgery. The eye is
prepped normally. Generally the non-dominant eye is selected for the
first go-around, leaving the fellow eye to wait a minimum of one week
before surgery on it. A Fox Shield is placed over the non-operated
eye to allow the patient to keep both eyes open. Standard draping is
employed and gloves are worn. Anesthesia consists of topical drops -
usually 0.5% Tetracaine - applied at the beginning and sparingly
throughout the case. While some surgeons advocate retro-bulbar
anesthesia its use is not warranted and some of these cases have
developed acute optic atrophy with total vision loss as a result. A
light wire lid speculum is inserted to keep the lids apart. The
patient fixates on the light of the microscope and the surgeon marks
the center of the optic axis onto the cornea with a blunt probe. The
primary (and secondary and tertiary zones if needed) are then marked
with special markers. The eye is fixated with special double pronged
forceps and the incisions made from the edge of the optic zone out to
the limbus. The knife blade used is generally a crystalline blade
such as sapphire for best results and more uniform cuts. Generally
the incisions are made 180x from each other and are arranged symmet-
rically around the circumference of the OZ. Upon completion of the
incisions, each one is gently irrigated with BSS. Antibiotic and cyc-
loplegic drops are then applied and the lid speculum removed. A light
eye patch (which the patient removes in about an hour) is then
By changing the pattern of the radiating incisions and incorporat-
ing tangential incisions, astigmatism up to 8 diopters can be cor-
rected. The range of expected correction of spherical myopia is from
<1 to 7 diopters, although higher corrections have been reported.
Post-operative care is minimal and the antibiotic/steroid drops
are stopped in two weeks. Vision is usually good from week one but
fluctuation of vision from morning to night can be expected for up-
wards of 6 months and sometimes longer. Glare at night can also be
expected for the same length of time. Some patients have complained
up to 3 years, however, glare testing shows no significant glare after
1 year in 99.3% of the cases. Approximately 83% of patients in the
expected range achieve 20/40 unaided (or better) vision post-op. Reg-
ression of effect over time has not been observed with the newer
techniques. The incidence of severe complications is rare and com-
pares favorably with those associated with the wearing of soft contact
lenses or spectacles. While there has been some recent unfavorable
publicity about serious complications none can be ascribed to the sur-
gery itself. Out of 280,000+ cases performed in the U.S., only two
eyes have been lost as a consequence of the surgery - both from post-
operative infection. Other complications such as cataract formation
have been due to physician error or the use of steroids. One case of
retinal detachment occurred as a result of the use of Phospholine
Iodide - a notorious culprit in producing this problem. There have
been some reports of continuing corneal flattening leading to over-
correction. These studies have defects which throw suspicion upon the
results and have not been corroborated by other workers. The PERK
study has many defects and is discussed in detail elsewhere.
Epikeratophakia was first described by Luis Ruiz, M.D. in 1980 and
has been called the "living contact lens". This is, of course, a mis-
nomer because while human tissue is used, it is by no means - alive.
The procedure uses pre-lathed human corneal tissue which is ordered
for the patient much like a contact lens. It is then sewn onto the
patients cornea where it remains unless removed. The procedure has
merit and finds its best indications in pediatric aphakia,
keratoconus, very high myopia or better high hyperopia, and some cases
of failed or over-corrected RK's.
The patient is prepped in the normal manner and is either
anesthetized generally or locally with a retrobulbar. After the lid
speculum is inserted, the corneal epithelium is scraped away and a
special suction trephine is placed in contact with the eye and suction
engaged. The trephine blade is rotated manually until it stops; it is
then removed. The action of the trephine is to produce a "V" shaped
groove in the stroma approximately 9 mm in diameter. The "V" is
cleared of adherent tissue and the bottom portion of the groove is un-
dermined slightly peripherally with a sharp spatula. The prepared
tissue, reconstituted in saline, is laid in place. Four cardinal
sutures are then placed. The suturing technique is such that the
suture exits just at the inferior tip of the tissue "wing" and enters
the recipient at the bottom of the undermined portion of the groove.
This serves to pull the tissue flat against the cornea and into the
groove. The "wing" or "skirt" of the tissue is then tucked in all
around and twelve more sutures emplaced. Appropriate antibiotics and
a cycloplegic are applied followed by removal of the speculum and
application of a pressure dressing.
Post-operative follow-up is quite like that of KM. The recovery
period is somewhat prolonged however. It can take as long as six
months to recover useful vision in some cases. In addition, some
cases of reduced post-operative best corrected vision have been
reported. Sutures remain in place for approximately 1 month. In the
event of infection or over or undercorrection or induced astigmatism,
the donor tissue can be pulled off under topical anesthesia (drops)
and new tissue applied.
Predicted results are, at this juncture, extremely variable and
not on a par with KM or RK. This will change with improvement in the
techniques of surgery and tissue preparation. The use of heteropathic
tissue has been considered but experimental work has only just begun.
This surgery has been removed from investigational status as of 1
March 1986. This move is considered premature by many because of the
recent change in protocol prior to the release. It is advised that
all patients selected for this surgery be considered as undergoing in-
vestigational surgery at this time.
All of these surgeries continue to elicit controversy despite suc-
cessful application of the techniques and the results. Some of the
cautious statements that were made in the beginning were valid then
but not today. However, some problems previously invisioned, have
resulted from inappropriate application or execution of these proce-
dures. None of these techniques are simple despite their appearance
to the contrary and are on a par with open heart surgery. No
general surgeon would dream of performing open heart surgery, leaving
that to specialists. So too refractive surgery. There are a myriad
of small details that must be constantly considered and concentration
on the case at hand is essential to success. Such necessity does not
fit in well with the general practice of ophthalmology. There is a
tendency to take short cuts and because of lack of experience overlook
data as insignificant. The proper performance of this surgery is best
left to specialists who have dedicated and are prepared to continue to
dedicate themselves to it. Teaching of these techniques should not be
done as a matter of course in a residency program but afterwards in a
program devoted to refractive surgery alone. This represents a shift
in my previous position on this subject. However, continued mis-
application of these techniques by general ophthalmic surgeons has
made this shift necessary.
The bibliography is available - see Part 1 of this article
Leo Bores, M.D.