First, do no harm. Those words embody the long-standing dismay
with which Medicine regards iatrogenic problems; that is, problems
inadvertently created by well-intentioned medical treatment.
A number of ophthalmic surgical procedures and medications can
precipitate the development of cataracts, necessitating the
replacement of the lens. And, unfortunately, “No technology that we
have available to date comes close to matching the vision of the
accommodating crystalline lens,” said Randall J. Olson, MD,
professor and chairman of ophthalmology and visual sciences, and
director, John A. Moran Eye Center, University of Utah, Salt Lake
City.
When Treating One Trouble
Creates Another
According to David F. Chang, MD, the leading causes of iatrogenic
cataract include medications, radiation and prior intraocular
surgery, including vitrectomy, trabeculectomy, penetrating
keratoplasty and peripheral iridectomy. “Another new cause of
iatrogenic cataracts is phakic IOLs,” said Dr. Chang, clinical
professor of ophthalmology at the University of California, San
Francisco, and in private practice in Los Altos, Calif.
Steroid therapy. “I would say 95 percent of the cases of
iatrogenic cataracts that I see are caused by the overuse of topical
steroids. Intraoperative and systemic steroids are also a problem,”
Dr. Olson said.
Mark Packer, MD, agreed. “Cataracts certainly occur with topical
steroid use, for example, in cases of prolonged application for the
treatment of uveitis. I have also seen posterior subcapsular
cataracts caused by topical steroids prescribed for blepharitis and
allergic conjunctivitis.” Dr. Packer is clinical assistant professor
of ophthalmology, Oregon Health & Science University,
Eugene.
Dr. Chang added, “A newer cause of steroid cataracts is the use
of intravitreal triamcinolone injections for retinal problems.”
Cataract prevention becomes more difficult when physicians
outside ophthalmology prescribe steroid medications. “You often see
posterior subcapsular cataracts in patients taking oral steroids for
pulmonary problems or arthritis,” explained Monica L. Monica, MD,
PhD, in private practice in New Orleans.
Dr. Olson added that oftentimes primary care physicians prescribe
steroid medications for patients with allergies or asthma without
completely understanding the repercussions these medications can
have. He cited his own case as an example. “I have taken inhaled
steroids long-term for asthma and nasal decongestion. I worry that I
could develop a cataract and/or glaucoma someday as a result of
this. I did not understand the risk because the prevailing wisdom
was that there was no systemic impact from the dose I was on. Now
the risk is clearly not zero but is still poorly understood.”
Phakic IOLs. There is no question that posterior chamber
phakic IOLs can cause cataracts, according to Dr. Olson.
Complicating matters further, the patients most likely to get these
implants are young high myopes, he explained.
“If they need cataract surgery, they are most at risk for retinal
detachment. That is to say, the most likely candidates for these
devices are also the patients with the highest risk for
complications. I am waiting to see what happens with this
technology,” Dr. Olson said. He pointed out that anterior chamber
and iris-supported phakic IOLs seem to do better, “but even with
these, it is too early to tell the long-term effects.”
Dr. Packer reported that with the iris-supported Verisyse phakic
IOL (AMO), the incidence of cataract surgery was 1.3 percent.
With the V4 ICL (Staar Surgical) it was 0.9 percent. The
incidence of anterior subcapsular opacification with the ICL was 2.2
percent. Both of these phakic IOLs have been approved by the FDA for
patients with high myopia.
Dr. Olson pointed out, however, that “when it comes to induced
cataract, five years’ worth of data is considered short-term. We
just don’t know yet.”
What we do know, according to Dr. Packer, is that “cataract is a
well-recognized complication of phakic IOL implantation and should
be discussed with all candidates.”
Intraocular surgery. Vitrectomy is the most common cause
of iatrogenic cataract in Dr. Chang’s practice. “The incidence
is essentially 100 percent,” he said.
“One theory is that higher oxygen levels near the crystalline
lens induce a nuclear cataract. With vitreous syneresis, or after
vitreous removal, the lens has much greater exposure to oxygen
levels from the choroid, and this induces nuclear sclerosis.”
Dr. Packer noted that he removed a cataract from a relatively
young, active general surgeon who had developed dense nuclear
sclerosis after a vitrectomy.
“The vitrectomy was performed for a posterior vitreous
detachment. The floater became intolerable to her when she was
performing surgery. We had an interesting discussion about IOL
choice. Eventually she decided on a monofocal IOL with a target
refraction of –0.75 D,” he said.
An antioxidant treatment may soon be available to prevent
cataracts after vitrectomy. The drug, OT-551 (Othera
Pharmaceuticals), is a topical eye drop that entered phase 2
clinical trials last year.1
Dr. Packer noted that the rate of cataract after trabeculectomy
for glaucoma is also very high. He noted that one study reported a
24 percent incidence of cataract after trabeculectomy in young
patients.2
What About
LASIK?
Can LASIK cause cataracts? Ironically and unfortunately, the
reverse may be true. According to Dr. Packer, “Cataracts have
actually been reported to cause LASIK!”
He cited a study of five patients with oil-drop cataracts. The
study noted that ophthalmologists had missed the underlying
lenticular cause of myopic regression after LASIK in these patients.
As a result, the patients were scheduled for or had had LASIK
enhancement before presenting to the study authors.3
Dr. Packer reported that he, too, has performed cataract surgery
for a patient who had two LASIK enhancements for “myopic
regression.”
The patient had dense nuclear sclerosis. “The patient told me
that he suspected the cataract was developing prior to the first
enhancement. Of course, the history of LASIK made his IOL
calculations problematic. He achieved 20/30 uncorrected acuity at
distance and near with a Crystalens implant,” Dr. Packer said.
According to Dr. Olson, cataract can occur after complicated
LASIK, although “I think the numbers are low, certainly less than 1
in 10,000.”
Dr. Monica added, “We have not seen cataracts developing soon
after LASIK. We do have patients who have had cataract surgery 15
years later after LASIK.”
When the First Problem May
Justify the Second
Even given a clear risk of inducing an iatrogenic cataract,
overriding medical priorities may justify it.
Dr. Chang explained it this way: “In most cases, iatrogenic
cataracts are caused by medical or surgical treatments for serious
ocular or general medical problems. Cataracts can be eliminated with
surgery, so the risk of cataract development usually is not a
contraindication to the primary treatment, such as prednisone for
asthma, or vitrectomy for macular hole.”
He noted, “One exception is elective phakic IOL refractive
surgery, which is usually performed in high myopes. Because cataract
surgery increases the incidence of retinal detachment, the risk of
iatrogenic cataract in this population of other-wise healthy eyes is
more onerous.
“If I were choosing a phakic IOL for a high myope, I would prefer
the one that has the lowest risk of iatrogenic cataract. To me, this
would be a much more important consideration than, say, incision
size, said Dr. Chang.
“We certainly need more long-term studies in order to better
quantify and compare the relative cataract risk of different phakic
IOL models,” he said.
“Any time one operates on a phakic eye, one must be cognizant of
the risk of cataract,” Dr. Packer said. “Informed consent for
surgical procedures on phakic eyes must include the risk of cataract
and the potential complications of cataract surgery, such as the
potential increased risk of retinal detachment in high myopia.”
If the well-informed patient opts for a procedure, then
“meticulous surgical technique may help to reduce the risk,
particularly in phakic IOL implantation,” Dr. Packer said.
Cataract as Usual, Unless It
Isn’t
When iatrogenic cataracts make an appearance, the diagnostic
considerations are usually no different than they would be if the
cataract occurred naturally, according to Dr. Chang. “One exception
would be the rapid development of a mature white lens following
vitrectomy surgery,” he said. “In this situation, one must suspect a
surgical violation of the posterior capsule.
“In general, eyes that have undergone vitrectomy are more likely
to have weak zonules, and a greater likelihood of lens-iris
diaphragm retropulsion syndrome,” he said. In any case,
ophthalmologists share with all physicians the risk of iatrogenic
effects: the problems induced by solutions.
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1 EyeNet 2006;10(2):15.
2 Adelman, R. A. et al. Ophthalmology
2003;110(3):625–629.
3 Soong, H. K. J Cataract Refract Surg
2004;30(11):2438–2440.
______________________________
Dr. Chang reports financial interests in AMO, Visiogen,
Cataract & Refractive Surgery Today, Slack and Alcon. Dr.
Monica has no related interests. Dr. Olson reports interests in
Allergan, AMO, Calhoun Vision and Becton-Dickson. Dr. Packer has
received travel, research and honoraria funds from Eyeonics, Staar
Surgical and Alcon, and he has consulted for AMO and Advanced Vision
Science.
