Adjustable intraocular lenses (IOLs) are uniquely poised to disrupt the refractive IOL arena for both cataract and refractive lens exchange patients. This is because they will not only improve refractive outcomes, but will dramatically enhance the patient experience as well. Patients will be able to postpone confusing decisions about refractive targets and objectives until they can preview them postoperatively. The unique benefit of being able to customize and “choose” their pseudophakic vision after the surgery will be understandable, desirable, and easily explained to family and friends.
Adjustable IOL, refractive surgery, cataract surgery, toric or presbyopia correcting IOL, bilateral simultaneous surgery
David F Chang is a consultant for RxSight, Powervision, J&J Vision, and Zeiss. No funding was received in the publication of this article. This article is a short opinion piece and has not been submitted to external peer reviewers.
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September 01, 2017
October 20, 2017
David F Chang, 762 Altos Oaks Drive, Los Altos, CA 94024, US. E: firstname.lastname@example.org
Harvard Business School professor Clayton Christensen popularized the concept of disruptive
innovation to explain why the most successful companies eventually fail. While the leading companies
continue to develop better and more expensive technology, they fail to anticipate a sea change in
the way new technology will be used and incorporated into their business or field—the disruptive
innovation. I believe that adjustable intraocular lenses (IOLs) are going to be the technology that
ultimately disrupts the field of refractive IOL surgery for both cataract and refractive patients alike.
Because both presbyopia and cataracts are normal aging conditions, the majority of patients eventually
become refractive IOL candidates. Surgeons and their patients will welcome the improvement in
refractive outcomes that adjustable IOLs will enable. Equally important, however, is how adjustability
will transform the patient’s refractive surgical experience—how patients will decide what specific
refractive outcome they want and how we will provide this to them. This is how adjustable IOLs are
poised to disrupt the competition.
Why have refractive IOL adoption rates been disappointing for the
past two decades?
Although they have been available in the US since the mid-1990s, adoption of multifocal and even
toric IOLs has been surprisingly low. That the additional costs are not covered by insurance is not
the only significant barrier to growth. Additional factors include: (1) our inability to deliver LASIK-like
refractive outcomes, (2) side effects from diffractive presbyopia correcting IOLs, (3) lack of surgeon
confidence in being able to satisfy most patients, (4) patient difficulty in understanding the value
proposition, (5) lack of patient word-of-mouth endorsement, and (6) lack of referring doctor promotion
of premium IOLs.
Imagine if we could not enhance our LASIK patients and only had one “shot” at hitting emmetropia.
Patient satisfaction, surgeon confidence, optometric endorsement, and positive patient testimonials
would all suffer. However, many thousands of refractive IOL patients are left with tolerable but
residual refractive error because the majority of cataract surgeons do not also perform LASIK.
We all dread facing patients who are disappointed with their refractive outcome or are distraught
by pseudophakic halos and starbursts. When technically perfect surgery was performed, this is
particularly demoralizing and reduces surgeon confidence in recommending presbyopia correcting
IOLs. Many optometrists who follow these dissatisfied patients over time develop a bias against
multifocal IOLs. Predicting preoperatively which patients might be more forgiving as opposed to
demanding or picky about their eyesight is an unreliable art. Even when patients are delighted and
pleased following their surgery, they do not know how much of the benefit is due to the cataract
removal versus their choice of IOL. Finally, ophthalmologists are perplexed by the frequent poor
correlation between surgical anatomic success, residual refractive error,
and subjective “20-happy” outcomes.
To gain wide popularity, a refractive procedure or technology must
consistently generate high satisfaction by all stakeholders—patients,
surgeons, and referring optometrists—along with fair and proper alignment
of financial incentives. The procedure should consistently meet or exceed
patient expectations, and generate “wow” experiences about which
patients will brag to their friends. LASIK satisfies all three stakeholders in
these ways and benefits from a brand name that the public recognizes and
remembers. However, a crucial component of LASIK’s success is our ability
to enhance the initial refractive result.
Unlike with LASIK, we cannot simply tell refractive IOL patients that they will
never need eyeglasses again. Instead, our cataract patients must struggle to
understand concepts such as focal point, depth of focus, contrast sensitivity,
astigmatism, hyperopia, myopia, and presbyopia. Comprehending these
optical concepts becomes fundamental to understanding the value
proposition of reducing, but not eliminating spectacle dependence. Patients
are much less likely to select more expensive options if they do not fully
understand the benefits, and this hinders adoption of toric IOLs despite
their lack of optical trade-offs.
What adjustable IOL technologies are in the
RxSight (formerly Calhoun Vision) developed the first light adjustable lens
(RxLAL). The 3-piece RxLAL includes diffusible, photosensitive silicone
macromers that are dispersed in the overall silicone matrix. Cataract
surgery with RxLAL implantation is performed using standard techniques.
Approximately 3 weeks later, the patient is refracted and a slit lamp based
digital light delivery device (LDD) system is used to deliver the ultraviolet
(UV) light in a precisely programmed pattern to induce a predictable change
in the shape and refractive power of the optic. Treatment times range
between 60-120 seconds. After the newly adjusted refraction is confirmed
several days later, a “lock-in” dose is given with the LDD to polymerize
all remaining macromer, at which point no further refractive change will
occur. Patients wear special UV-blocking spectacles until the lock-in step is
completed, after which they are no longer required.
As a phase II investigator, I implanted the first 16 RxLALs in the US. Patients
readily understood the concept and were willing to temporarily wear UVblocking
spectacles for the long term benefit. The slit lamp light adjustments
were performed with a contact lens, much like a YAG capsulotomy, and
were easily tolerated. Following implantation, adjustment, and lock-in,
the result is an intracapsular, three-piece monofocal IOL, which avoids
the long-term anatomic uncertainties associated with drastically different
IOL designs. The RxLAL completed the US phase III trial in early 2016 and
submitted its Premarket Approval (PMA) application to the US Food & Drug
Administration (FDA) later that same year.
Perfect Lens LLC is developing a novel technology called refractive index
shaping (RIS) that can modify the refractive properties of an implanted
IOL in situ with a femtosecond laser. RIS can be used to postoperatively
modify spherical aberration, toricity, and even multifocality of an
implanted IOL. Rabbit studies have provided in vivo proof of concept with
maintenance of good modulation transfer function. Human clinical trials
have not yet begun.
With advances in biometry, IOL formulae, and
intraoperative aberrometry, do we need an
Although new formulae, improved biometry, and intraoperative wavefront
aberrometry have incrementally improved our ability to select the optimal
IOL sphere, cylinder, and axis, they are still simply predictions that improve
the mean—our batting average—without eliminating the standard deviation.
We still cannot preoperatively measure and must therefore estimate each
individual eye’s effective lens position, posterior corneal astigmatism, and
surgically induced astigmatism. Instead of relying on predictions, adjustable
IOLs will treat the stabilized postoperative refraction, and should appeal
to anyone desiring a specific refractive target with a monofocal IOL.
They would be especially valuable for eyes at greater risk for IOL power
surprise, such as those with prior keratorefractive surgery, mature cataracts
impeding optical biometry, rigid contact lens wear, atypical keratometry,
and a very short or long axial length.
Even without these risk factors, an adjustable IOL would provide enhanced
assurance against being one of the 15–35% of patients that do not end
up within 0.5 D of the intended target. Imagine hypothetically that there
were two different LASIK procedures—one that you could not enhance,
and a second, more expensive procedure that would allow enhancements.
Which would you choose to have? Would you take your chances with the
less expensive alternative because the refractive results are usually good
in most patients?
The RxLAL submitted for FDA approval in the US will allow adjustment of
sphere and cylinder and I believe it will achieve the best outcomes for low
to moderate astigmatism. Although mean surgically induced astigmatism
can be determined, the standard deviation of this value is significant at
approximately 0.5 D. Posterior corneal astigmatism is difficult to measure.
The effect of either manual or femtosecond laser astigmatic keratotomy
still varies with corneal rigidity and may regress unpredictably over time.
In addition, although misalignment greater than 10 degrees is uncommon,
we cannot predict or prevent smaller degrees of toric IOL rotation. With
an adjustable IOL, predicting posterior corneal and surgically induced
astigmatism will not matter because we will be treating the stabilized
postoperative refraction long after any IOL rotation has already occurred.
Although I currently employ corneal topography and wavefront aberrometry,
swept-source optical coherence tomography (OCT) biometry, multiple
advanced formulae, intraoperative aberrometry, and digital intraoperative
axis localization, ophthalmology residents using only basic biometry
should achieve better astigmatism outcomes with an adjustable IOL than
I currently do using all of these technologies. This innovation will therefore
disrupt what we currently do for preoperative and intraoperative testing.
Disrupting the patient experience—choosing your
As the number of different IOL choices increases, surgeons are spending
increasing amounts of preoperative chair time discussing refractive options
and targets. These are difficult and anxious decisions for patients because
the competing choices have different tradeoffs, and yet there is no way to
try them out. It is challenging for preoperative patients to comprehend the
difference between being plano or -1.00, the difference between having
1 D of astigmatism versus none, and the difference of 1 versus 1.5 D of
intentional anisometropia for mini-monovision. Patients must make these
lifelong decisions prior to surgery, and after finally selecting a refractive
objective, we then add the disclaimer that we cannot guarantee producing
a specific refractive outcome. Most surgeons spend far more time on
preoperative counseling than on the actual surgery. Having to decide
preoperatively among confusing and expensive choices that they cannot
preview or later easily reverse is a stressful experience for patients.
By solving these problems, adjustable IOLs will appeal to both patients
and surgeons. Patients can wait until they are pseudophakic to have an
optometrist demonstrate different options to them postoperatively using
the phoropter, trial lenses, or disposable soft contact lenses. After sampling
different refractive outcomes, patients can then “choose” their eyesight. We
can demonstrate how much better vision without astigmatism would be.
For patients whose priority is reading without glasses, we can simulate the
difference between -1.50 or -2.50. After they try it for a day with a SCL trial,
we can create, reverse, and adjust pseudophakic mini-monovision. We can
let patients choose the optimal amount of myopia for their near eye, and
then confidently deliver that very outcome along with excellent distance
acuity in the far eye. In recent American Society of Cataract and Refractive
Surgery (ASCRS) Clinical Surveys, pseudophakic monovision was used
much more frequently than presbyopia correcting IOLs. Adjustability and
reversibility should make this strategy even more popular, and will avoid the
risk of significant dysphotopsia with diffractive presbyopia correcting IOLs.
Although most pseudophakic patients are happy with 20/25 and 20/30
uncorrected distance acuity, adjusting away their residual refractive error
might produce 20/20 or 20/15 uncorrected vision. This adjustment could
be a “wow” experience for patients, surgeons, and referring optometrists.
Although keratorefractive surgery can correct residual refractive error,
it carries the psychological barrier of requiring another “surgery” with
informed consent forms that describe some surgical risk. In addition,
many cataract patients have dry eyes and many cataract surgeons do not
perform keratorefractive surgery and may not have a partner who does.
The analogy of buying a dress or suit works nicely for explaining the
concept of IOL adjustment and customization to patients. You can buy a
suit off the rack at the department store, which allows you to try the next
size up or down. This is how we fit soft contact lenses. You can buy your
suit over the Internet based on a few measurements with the hope that it
will fit. This is how we select your IOL for cataract surgery because we can
only implant and try out one lens power. Finally, you could have a tailor
make alternations once you are wearing the suit so that it is custom fit to
your body. This would be like adjusting your lens after it is inside your eye.
Extended depth of focus (EDOF)
This IOL category is growing in popularity for pseudophakic presbyopia
correction. The tradeoffs of true monofocal monovision, such as loss or
reduction of binocularity and depth perception, are well known. One
strategy is to enhance depth of focus by increasing total ocular spherical
aberration (SA). Mini-monovision with EDOF optics may provide good
near function while preserving binocularity and avoiding the optical
compromises associated with diffractive optics. Of course corneal SA
varies individually within the general population. RxSight can create EDOF
optics postoperatively by precise alterations in SA. This can be done in
a way that allows pseudophakic patients to preview several possible SA
profiles, and to select the one that works best for their eye, based on their
corneal aberrations. Of course, this additional indication will require a new
Once approved for this indication, I believe that mini-monovision with
adjustable IOLs employing EDOF optics will also be a game changer for
refractive lens exchange (RLE). This strategy should appeal to the large
population of patients in their 50s and 60s who covet and can most
afford a lifestyle-enhancing, presbyopia-correcting refractive procedure.
Compared to current diffractive IOL technologies, this strategy using
monofocal IOLs preserves the highest-quality vision and reduces optical
tradeoffs, such as halos, glare, and reduced contrast sensitivity. This is
crucial because, unlike cataract patients, the RLE patient population already
has excellent quality of vision. To mirror the high success rate of contact
lens monovision, the key prerequisites will be achieving outstanding
distance vision in one eye, and customizing the amount of myopia
in the near eye. Because it would be reversible, the risk of intolerable
anisometropia would be mitigated. Unlike with keratorefractive surgery,
the benefits will not later be lost due to cataracts; indeed, patients will enjoy
knowing that they will never develop cataracts in the future. If adjustable
EDOF optics can achieve spectacle independence with mini-monovision
while minimizing dysphotopsia and maximizing optical quality, this could
easily become the most popular presbyopia correcting strategy for both
cataract and RLE patients.
Disrupting simultaneous bilateral surgery and
global refractive IOL adoption
I predict that many adjustable IOL patients will elect to have bilateral sameday
sequential surgery, just as most patients now do with LASIK. Thanks to
shrinking complication rates, bilateral same day cataract surgery is gaining
in popularity in many countries and settings where there is no financial
disincentive to operating on both eyes simultaneously. One benefit of staging
surgeries separately has been the ability to alter the refractive game plan
after the first eye results become apparent to the patient and surgeon. For
example, many myopic patients coveting excellent uncorrected distance
vision become dismayed to find postoperatively how often they must don
readers to see anything close. Sequentially staged surgery allows us to
target some myopia in the second eye. It also allows the surgeon to make
compensatory adjustments to IOL power selection following a refractive
surprise in the first eye.
Adjustability would solve both of these problems. Furthermore, simultaneous
bilateral adjustable IOL surgery allows patients to immediately experiment
with different binocular refractive strategies—e.g., bilateral distance or low
myopia, mini-monovision, true monovision, and which is the preferable
“distance” eye. Conveniently for patients, optometrists, and ophthalmologists,
the postoperative counseling, refractions, adjustments, lock-ins, and
examinations could all be simultaneously performed for both eyes. This
would also shorten the period that UV protecting glasses would need to be
worn. Busy patients will value the reduction in office visits while also avoiding
the intervening visual imbalance or anisometropia that accompanies
sequentially staged cataract procedures. The refractive premiums should
more than offset any reduction in insurance reimbursement.
Aside from several smaller international markets, the premium refractive
IOL channel is unique to the US because our healthcare regulatory system
properly differentiates between the refractive and medical aspects of
cataract surgery. American patients gain access to available refractive
technologies because they are allowed to pay for non-medically necessary
services, without simultaneously sacrificing their healthcare benefits. One
regulatory inconsistency, however, is that patients desiring monofocal
monovision cannot be billed for refractive services despite requiring just
as much preoperative evaluation, counseling, and testing as a presbyopia
correcting IOL patient.
From the standpoint of international healthcare regulations and patientshared
billing, one benefit of adjustable IOLs is the obvious and legitimate
separation of the refractive treatment from the cataract operation.
Analogous to LASIK for a pseudophake, the IOL refractive adjustment is
not medically necessary and does not take place in the operating room
at the same time as the cataract surgery. This LASIK-like model should
finally unlock global markets where government health plan restrictions
have constrained patient access to premium refractive IOLs. This is typically
because the patient must entirely forgo their covered health benefits to
obtain a premium IOL privately outside the system.
Addressing the future manpower shortage in
As the baby boomer generation ages further, a significant manpower
shortage in ophthalmology will require ophthalmologists to work closely
with optometrists. Adjustable IOLs will provide a perfect opportunity for
such collaboration because optometrists embrace and are ideally suited for
something that most surgeons would prefer to delegate—patient refractive
counseling. Optometrists already excel at monovision contact lens fittings
because they can patiently spend the chair time necessary to employ
trial and error with different lens powers. If a pseudophakic patient wants
to test and compare multiple options postoperatively using trial frames
or soft contact lenses, then the optometrist can charge refraction fees
commensurate with the amount of time spent. The optometrist will then
send the patient back to the surgeon for their postoperative IOL adjustment
along with the target refractions that the patient has selected.
This model not only relieves cataract surgeons of the primary refractive
counseling responsibility, but allows optometrists to be recognized and
appreciated by the patient for their essential role in the overall process.
Happy refractive patients will be eternally grateful to the optometrist that
took the time to explain and demonstrate the best options. This in turn will
cause optometrists to favor and recommend the adjustable IOL model—
both because of the ability to do the refractive counseling postoperatively,
and because of the superior refractive outcomes that non-adjustable
IOLs cannot match. Finally, the patient-centered benefit of simultaneous
bilateral cataract surgery with adjustable IOLs will also improve the
efficiency and capacity of optometrists and ophthalmologists to meet
our population’s expanding need for cataract and IOL-based refractive
surgery. Increasing global adoption of RLE will also reduce the cataract
surgical burden for future generations of ophthalmologists and for the
healthcare system as a whole.
Why adjustable IOLs will be a disruptive
In summary, adjustable IOLs will deliver multiple new benefits to all three
stakeholders—patient, cataract surgeon, and referring optometrist. It is not
just the IOL technology that will change, but also the process by which
patients will choose their refractive objective, and how optometrists and
surgeons will deliver it. Most refractive counseling will shift from preop
to postop, with cataract surgeons delegating this important but timeconsuming
task to optometrists. The smaller incremental gains afforded
by advances in biometry, IOL formulae, digital intraoperative alignment
systems, and intraoperative aberrometry could be rendered superfluous by
postoperative IOL adjustability. Because of better refractive accuracy, this
technology should immediately become the best toric IOL, the preferred
monofocal IOL, and the most popular presbyopia correcting strategy.
Patient satisfaction will soar to new heights. After previewing and
comparing different refractive outcomes, some pseudophakic patients
may prefer being -1.00 in each eye, while others will want mini-monovision
with EDOF optics. With respect to the value proposition, they will not need
to fully comprehend what astigmatism is. They can simply observe using
trial lenses what their vision would be with or without correcting it. Finally,
knowing that they can more knowledgeably participate in the decision by
comparing different options postoperatively will alleviate the confusion and
anxiety that so many of our patients now experience preoperatively
Observing the obvious refractive benefits and accuracy, referring
optometrists will embrace this model and recommend adjustable IOL
technology to their patients before they even visit the surgeon. Surgeons will
be relieved at no longer having to guess which patients will love a diffractive
multifocal and which ones will hate it. And patients who experience the
“wow” of their adjustment will better understand the separate value of
adjusting and customizing their “prescription” postoperatively, and will
champion the technology to their friends.
Untapped global markets for premium IOLs will be unlocked by adjustable
IOL technology. In addition to the refractive lens exchange market, clear
differentiation between the surgical treatment of cataract and the optional
refractive enhancement will allow millions of international cataract patients
to access refractive IOL technology and services that their healthcare system
currently prevents. Finally, adjustable IOLs will help ophthalmology meet the
rising cataract surgical demand by fostering bilateral simultaneous surgery
and the delegation of virtually all perioperative refractive counseling to
optometrists. Patients will be the biggest winners thanks to better refractive
outcomes than we have ever provided, and the ability to experience and
choose what refraction they want before making a decision to target and
pay extra for it.