Lasik Eyes Surgery - Dreaded complication of LASIK

Author

Dreaded complication of LASIK

Informer

2005-05-18, 11:47 am

Ectasia is when your eyes start bulging forward because your post- LASIK
cornea is too weak
to support your intraolcular pressure. Ladies, when your corneas begin to
thin when you hit
menopause and your eyes are drier... will you need a corneal tranplant???

http://www.crstoday.com/PDF%20Artic..._f7_Tauber.html

Excerpts from the full text:

Keratoectasia: a Dreaded Complication of LASIK

By Shachar Tauber, MD

PREOPERATIVE SCREENING

I divide ectasia into the preoperative risk factors for developing it.
Screening patients preoperatively for their susceptibility to ectasia
involves a careful examination for evidential markers.

Changing Refraction

First, I examine the stability of the patient's refraction. Someone who
presents with a refraction or keratometry that has changed significantly
needs his refractive stability evaluated over several months. If he is in
his early 20s, he may be a premature keratoconus patient. One should be
concerned about contact-lens or spectacle intolerance due to unstable
refractions as well as a BCVA of less than 20/20 if no ophthalmic pathology
is evident.

Suspicious Medical History

A history of atopic dermatitis or chronic conjunctivitis, although not
necessarily a risk factor for ectasia after LASIK, is reason enough to
further work up a patient before considering treating him with refractive
surgery. Chronic eye rubbing also denotes a poor refractive surgery
candidate.

Type of Refraction

Work performed by Doyle Stulting, MD, and others showed that ectasia is
extremely rare in low myopia.1 Among risk factors they identified for
developing ectasia were refractions greater than -8.50D, a residual stromal
bed, and evidence of forme fruste keratoconus.

PREOPERATIVE CORNEAL MAPPING AND PACHYMETRY

All the aforementioned conditions require further investigation. I would not
necessarily rule out performing LASIK in these patients, but I would proceed
cautiously. I will not perform LASIK on a patient who cannot stop rubbing
his eyes. Likewise, I reject LASIK for those whose preoperative mean
keratometry is above 47.20D or whose central corneal pachymetry is less than
500µm, regardless of their prescription in either case. I will instead
recommend surface ablation to those patients. I have been performing more
surface ablation in recent years, because I have become less tolerant of the
potential risks of LASIK (Figures 2 and 3). Furthermore, I do not feel that
new technology, such as the Intralase FS laser (Intralase Corp., Irvine, CA)
has sufficiently alleviated those risks to make me more comfortable
performing LASIK than surface ablation.

I use keratometry and topography to rule out any suspicion of forme fruste
keratoconus. A difference in inferior and superior steepening of more than
1.50D might indicate an irregular cornea. If I see topographic or
keratometric evidence of irregular astigmatism, or if I cannot correct the
patient to 20/20 despite a normal preoperative examination, then I will
choose surface ablation.

INTRAOPERATIVE PRECAUTIONS

The most important thing for the refractive surgeon to know is the
parameters of his devices. I am extremely nervous when asked to try a new
microkeratome, because I do not know how it will cut in my hands. It
behooves each surgeon to measure and keep track of the thickness of the flap
in every LASIK case. I use the Moria 1 disposable microkeratome unit (Moria,
Antony, France), with which I produce flaps from 90- to 135µm. I always use
the thickest flap I have ever created as a basis for calculating a patient's
ablation depth and amount of residual stroma. I will plan to leave 300µm in
the stromal bed after laser application as opposed to the FDA's recommended
250µm for a primary LASIK procedure.

To calculate the residual stromal bed, I measure the stromal depth before
ablating it and then postoperatively subtract the amount that the laser
indicates it has removed from the central cornea. Subtraction technology is
currently the best way to measure flap thickness, although a more direct
method would be preferrable. I make sure to include these data in the
patient's chart so that, if he returns for an enhancement, I know the
postoperatively calculated stromal bed.

Also on the subject of enhancements, surgeons must review any available
surgical notes preoperatively so that they know the original ophthalmologist's
intent. When it is time to relift the corneal flap to perform the
enhancement, the surgeon needs to know (1) how much tissue is available and
(2) how much he is going to remove in order to calculate the residual
stromal bed. For example, if 350µm of tissue is available after measuring
under the flap, calculating the ablation for 120µm will certainly leave less
stromal tissue than the FDA's recommendation of 250µm, and the surgeon will
have to abort the procedure. Aborting a procedure is a difficult chore for a
surgeon, but preoperative planning can avoid it. If planning reveals that
the flap is thicker than anticipated, then the surgeon's best option is to
put the flap back down. The literature supports laser surface ablation
treatments on the flap itself for such patients at a later date,2 which is
an important option to remember.

TREATING ECTASIA AFTER LASIK

Diagnosing ectasia after LASIK is critical, because these patients tend to
have wonderful early postoperative results and only schedule a return visit
when they have problems. One hopes that they will see their operating
surgeon, because he has all their data. My staff and I strongly encourage
our patients to return to us if they experience a postoperative problem. We
tell them that their data are important to us. We always take postoperative
topographic measurements with an Orbscan topographer (Bausch & Lomb,
Rochester, NY) at 1 month and measure the pachymetry at 3 months. We record
both of these calculations in the patient's chart. If we see myopia
developing, we follow it for 1 to 2 months while taking serial topographies
and refractions to make sure the refraction is stable. I become very
suspicious if the patient's BCVA is less than it was in the preoperative or
early postoperative period. A patient who becomes myopic, who develops some
astigmatism, and whose BCVA drops to 20/30 is a big concern.

Making the diagnosis is important because it is very tempting to
automatically enhance an eye. In following such an individual, I use the
Orbscan topographer and examine the posterior float, which I use as a
tie-breaker rather than an absolute determination. I rely on other clinical
and historical findings to give the diagnosis much more weight than an
abnormally elevated posterior float from the patient's Orbscan.

Once I have diagnosed ectasia, I inform the patient and advise him about his
treatment options. I explain that my goal is to improve his BCVA. This is a
critical time for the operating surgeon, who has earned the trust of and
developed a good rapport with the patient. On the other hand, a surgeon whom
the patient has sought for a second opinion must spend time with the patient
and deal with his anger, disappointment, and shock at the situation, even if
he understood the risks. A patient who has to revert to using contact lenses
will almost always resist this treatment, because he underwent refractive
surgery to eliminate this dependence. The surgeon must be cognizant,
empathetic, and supportive of the patient's duress, but he must also be firm
in delivering his advice. I tell the patient that contact lenses are likely
his best option, because they have the highest likelihood of improving his
visual acuity to a satisfactory level.

MANAGING IOP

In my early management of ectasia, in addition to using a contact lens, I
will lower the patient's IOP with a beta-blocker (Betimol; Santen Inc.,
Napa, CA) once or twice per day if the patient tolerates it. If an IOP
component is furthering the ectasia, the beta-blocker may retard or limit
it. I think this approach is worth a trial early on. This type of
beta-blocker usage has had few case reports,3 but it has been impressive in
very mild cases of ectasia. Certainly, full-blown keratoectasia will not
respond to IOP lowering.

Finally, if the patient cannot tolerate contact lenses, I will explore every
possible means of treating the ocular surface to make this modality viable.
For patients who simply cannot wear a contact lens, intrastromal corneal
ring segments (Intacs; Addition Technology, Inc., Des Plaines, IL) are a
very interesting option. I am planning to use them for several patients to
treat their ectasia. Although the available literature on Intacs is early,
it seems to support their use as a modality for ectasia once contact lenses
have failed,4 and I think the approach is definitely worth a try. The only
other alternative is corneal transplantation, which is a last resort because
of the intraocular nature of the procedure and the long-term immunological
and postoperative care those patients need.

Glenn - USAEyes.org

2005-05-18, 11:47 am

Fortunately, this dreaded complication of LASIK occurs in about 1 to 5
in 10,000 LASIK cases. Thanks to diligent preoperative evaluations
such as described in the article cited, the incidence of refractive
surgery induced ectasia is about the same as the incidence of
naturally occurring keratoconus. studies are underway to determine if
unexplained LASIK related ectasia is not actually undiagnosed
keratoconus.

For more on prevention/treatment of ectasia and keratoconus, visit

http://www.usaeyes.org/faq/subjects/thickness.htm

http://www.usaeyes.org/faq/subjects/keratoconus.htm

Glenn Hagele
Executive Director
USAEyes.org

"Consider and Choose With Confidence"

Email to glenn dot hagele at usaeyes dot org

http://www.USAEyes.org
http://www.ComplicatedEyes.org

I am not a doctor.

CatmanX

2005-05-18, 11:47 am

There is a lot of discussion going on as to whether eye rubbing is a
component of keratoconus. It would be interesting to see if the
Suspicious Medical History of atopic dermatitis or chronic
conjunctivitis is associated with rubing, and hence may be a progenitor
of ectasia. THis would mean that the surgery would be implicated, but
the stressor was the patient themselves. This would also explain the
group that develops ectasia with a stromal bed thicker than 240
microns.

dr grant

Glenn - USAEyes.org

2005-05-18, 11:47 am

Eye rubbing is an absolute contributor to keratoconus and thereby
ectasia. Rubbing the eyes releases free radicals, disrupts the
lamellar fibrils, and does all sorts of things that we never even
think about.

Glenn Hagele
Executive Director
USAEyes.org

"Consider and Choose With Confidence"

Email to glenn dot hagele at usaeyes dot org

http://www.USAEyes.org
http://www.ComplicatedEyes.org

I am not a doctor.

Richard

2005-05-18, 11:47 am

Glenn - USAEyes.org <glenn.hageleSTOPSPAM@USAEyes.org> wrote in
news:bpsl81lnghq6hohtsjvn13t1lt4ngdqd7o@4ax.com:

> Eye rubbing is an absolute contributor to keratoconus and thereby
> ectasia. Rubbing the eyes releases free radicals, disrupts the
> lamellar fibrils, and does all sorts of things that we never even
> think about.

I used to rub my eyes, but, during the healing process after LASIK, I had
to be ultra careful not to do so, and thus, got out of the habit...

--
Richard

Ragnar

2005-05-18, 6:02 pm

I got into the habit of never rubbing my eyes when I wore rigid
contacts. The hard, knife-like edges will tear your epithelium off
quite easily.

On 18 May 2005 14:32:07 GMT, Richard <RichardRapier@netscape.net>
wrote:

>Glenn - USAEyes.org <glenn.hageleSTOPSPAM@USAEyes.org> wrote in
>news:bpsl81lnghq6hohtsjvn13t1lt4ngdqd7o@4ax.com:
>
>
>I used to rub my eyes, but, during the healing process after LASIK, I had
>to be ultra careful not to do so, and thus, got out of the habit...

Graeme Hewson

2005-05-18, 6:02 pm

On 18 May 2005 14:32:07 GMT, RichardRapier@netscape.net (Richard) wrote:

> I used to rub my eyes, but, during the healing process after LASIK, I
> had to be ultra careful not to do so, and thus, got out of the
> habit...

Here's a tip for anyone having surgery soon (as I am). I have a pair of
so-called prescription swimming goggles (off-the-shelf with spherical
correction only) and tried sleeping in them. They got quite sweaty
after a few hours, so I drilled a hole in the side of each lens. That
should stop me doing any damage to my eyes when I'm only half awake.

Ragnar

2005-05-18, 6:02 pm

You will get a kit that includes eye shields and goggles to wear.
The primary reason for them is so you don't rub your eyes withing the
first 24 hours.
Keep in mind that your prescription goggles will now give you
distorted vision after your surgery.

On 18 May 2005 19:31:49 GMT, ghewson@cix.co.REVERSE:ku (Graeme Hewson)
wrote:

>On 18 May 2005 14:32:07 GMT, RichardRapier@netscape.net (Richard) wrote:
>
>
>Here's a tip for anyone having surgery soon (as I am). I have a pair of
>so-called prescription swimming goggles (off-the-shelf with spherical
>correction only) and tried sleeping in them. They got quite sweaty
>after a few hours, so I drilled a hole in the side of each lens. That
>should stop me doing any damage to my eyes when I'm only half awake.

Graeme Hewson

2005-05-18, 6:02 pm

On Wed, 18 May 2005 19:44:37 GMT, ragnarsuomi@yahoo.com (Ragnar) wrote:

> Keep in mind that your prescription goggles will now give you
> distorted vision after your surgery.

They'll let the water in, too. Gee, they're not going to be much use at
all, really.

serebel

2005-05-19, 12:06 am

Learn something new every day. I used to practically rub my eyes into
the back of my head before lasik.

SErebel

Ragnar

2005-05-19, 8:57 am

What is the Rx on those goggles? I recall that the goggles are only
available for a few diopters of correction.
I was always surprised at how few swimmers use the prescription
goggles. How did they word for you? How much?
I think they are a great idea for teenagers too young to have lasik.

On 18 May 2005 20:19:33 GMT, ghewson@cix.co.REVERSE:ku (Graeme Hewson)
wrote:

>On Wed, 18 May 2005 19:44:37 GMT, ragnarsuomi@yahoo.com (Ragnar) wrote:
>
>
>They'll let the water in, too. Gee, they're not going to be much use at
>all, really.

2005-05-19, 8:57 am

In article <8gmo81lnqc46ucr8b6sk51d8hdf7iug8kn@4ax.com>,
Ragnar <ragnarsuomi@yahoo.com> wrote:

> What is the Rx on those goggles? I recall that the goggles are only
> available for a few diopters of correction.
> I was always surprised at how few swimmers use the prescription
> goggles. How did they word for you? How much?
> I think they are a great idea for teenagers too young to have lasik.

My 9 year old uses -6 prescription swim goggles. They come off the rack
at 1 diopter gradations. They are made by speedo and cost about $20.
He also has a prescription scuba mask. The lenses are replaceable as
his prescription changes.

--
~RT
The truth lies somewhere between Ragnar and LASIKtruth
Two sides of the same coin