Monovision With the Light Adjustable Lens for Presbyopia ... - Iogen

COVER STORY
Monovision With the
Light Adjustable Lens for
Presbyopia Correction
The lens can be adjusted postoperatively to optimize monovision or
switch to emmetropia in both eyes.
There are a variety of therapeutic approaches to
presbyopia correction, all of which have the
same goal: to provide patients with spectacle
independence. Currently, implantation of multifocal
or accommodating IOLs and pseudophakic
monovision are popular options; however, these often
require an additional refractive procedure after treatment
to achieve spectacle independence. Despite
advances in biometry and small-incision surgery, the
accuracy of IOL calculation remains limited by the variation
in the measurements of corneal power, axial length,
and anterior chamber depth.
One potential alternative to avoid the need for secondary
correction of presbyopia and residual refractive
50 I CATARACT & REFRACTIVE SURGERY TODAY EUROPE I JANUARY 2009
BY CHRISTOPH WINKLER VON MOHRENFELS, MD
error is the Light Adjustable Lens (LAL; Calhoun Vision,
Inc., Pasadena, California). The LAL contains photosensitive
macromers that enable a noninvasive postoperative
adjustment of refractive power using ultraviolet light
(UV light; 365 nanometers). These molecules are precisely
distributed throughout the lens; approximately 2
weeks after implantation, they are irradiated with UV
light to cause selective polymerization.
Photoreactive macromers dispersed within the crosslinked
silicone lens matrix are photopolymerized upon
exposure to UV light with a special selected spatial intensity
profile. With this irradiation, the photoinitiator initiates
polymerization of the macromer photoreactive
groups to form an interpenetrating polymer within the
Figure 1. All LAL treatments include the polymerization (ie, adjustment) and two lock-in procedures.

TAKE-HOME MESSAGE
• Photosensitive macromers in the LAL are distributed
through the lens and are polymerized when they are
irradiated with UV light.
• Diffussion of the remaining, unirradiated macromers induces
a change in the lens shape, the refractive index, or both.
• Patients can be adjusted to emmetropia in both eyes if
they do not tolerate monovision.
lens matrix. Diffusion of the remaining, unirradiated
macromers into the irradiated areas induces a change in
the lens shape or refractive index, or both, to produce a
predictable power change. Every adjustment procedure
allows 2.00 D correction of myopia, hyperopia, and astigmatism.
It is important that all photoreactive macromers
are polymerized, and every patient has to undergo two
lock-in procedures (Figure 1).
The LAL may be used during cataract surgery or for
refractive lens exchange. Currently for monovision, the
correction in the dominant eye is aimed for distance
emmetropia; the other eye is aimed for -1.00 D. Two
weeks after surgery, we evaluate patient satisfaction. If
the patient is doing well with monovision, the correction
is locked in. If the patient does not tolerate monovision,
he is adjusted for emmetropia.
CASE REPORT
A 58-year-old patient presented with cataract and a
preoperative refraction of -5.00 -0.50 X 170° and
-5.25 -0.75 X 18° in the right and left eyes, respectively.
The LAL was implanted bilaterally; the right was targeted
for emmetropia and the left for -1.00 D. Two weeks after
surgery, his far UCVA was 1.0 in the right eye and 0.6 in
the left. Near visual acuity was J2. We discussed the possibility
of more or less myopia in his left eye; however, he
was satisfied with the far and near visual acuities.
Therefore, we locked in both eyes.
CONCLUSION
Monovision, with the use of this technology, provides a
good refractive and visual outcome. The LAL may be able
to provide a multifocal correction in the future; however,
this is not yet possible. In my opinion, use of this technology
will be important for the correction of presbyopia
because it provides a perfect distance refraction. ■
Christoph Winkler von Mohrenfels, MD, is a surgeon at
Technical University, Munich, Germany. Dr. Winkler von
Mohrenfels states that he has no financial interest in the
products or companies mentioned. He may be reached at
e-mail: christoph.wvm@web.de.