lenses (IOLs) are designed to primarily restore
the refractive power of the eye after a cataract
surgery. However, with rapid technological breakthroughs,
IOLs are now available in various new and sophisticated
designs. These advanced models offer specialized
functions like multifocality, toric corrections,
pseudoaccommodation, blue-light blocking, photochromic
operations and what not. Most of these new designs
have been triggered by advancement in surgical
methods such as very small incisions and wavefront
aberrometry. A look at these various IOLs according
to their specific features reveals an array of
Multifocal intraocular lenses
There are a few important points to remember
before opting for a multifocal IOL:
- Control of astigmatism is essential.
- Accurate biometry is needed.
- Patients must
be selected carefully to reduce the high
probability of decreased
and glare caused by these lenses.
method has a direct effect on the outcome
on the use of these lenses.
The various multifocal lenses currently available
The Array is the first multifocal IOL approved
by the Food and Drug Administration (FDA). It
is a three-part multifocal IOL made of a silicone
material with a refractive index of 1.46. Some
studies that compared bilateral implantation
of the Array with a monofocal lens (at the backdrop
of visual quality and patient feedback) reported
the following points:
- Better uncorrected and distance corrected
near visual clarity.
- Better overall eyesight.
- Lesser imperfections
of visual operations.
- Reduced spectacle
However, some other studies failed to report
noteworthy changes in contrast sensitivity with
average and high glare.
This second-generation refractive, multifocal
IOL is an adaptation of the Array. It is a recent
product from Advanced Medical Optics, California.
This lens is created from a hydrophobic acrylic
material with a refractive index of 1.47.
The features of this lens are:
- Optical design based on the Balanced View
Optics Technology, with five concentric zones
modified from the Array model.
the new OptiEdge design combining three components:
1. A rounded anterior edge to decrease
2. A sloping side edge to reduce the surface
area that can trigger internal reflections
and to disperse internal reflections away
3. A square vertical posterior rim to help
The ReSTOR lens is also a current addition to
the multifocal IOL family. This is an apodized,
diffractive IOL, adapted from a single-piece
AcrySof lens. Its design ensures suitable near
and far vision when the pupil is small, for instance
while reading. On the other hand, it adjusts
to a large pupil condition for instance at nighttime
and ensures suitable distance vision while minimizing
unexpected visual aberrations.
This lens features the Z-Sharp Optic Technology.
It has an anterior aspheric surface that offsets
positive corneal aberration. A Tecnis design
(model ZM001) with a diffractive posterior surface
is currently being developed.
Toric intraocular lenses
TORIC IOLS are designed to correct cataract
related pre-existing astigmatism. Hence, they
must ensure proper centration, fixation and constancy
without rotational movements.
The Staar Surgical
This silicone-made posterior chamber IOL is
a single-piece toric (models AA-4203TF and AA-4203TL).
It provides cylindrical correction with a spherical
Alcon’s model SA60TT
This recently launched lens is another toric
model adapted from a single-piece AcrySof IOL.
This lens shows more stability and less postoperative
Blue Blocking Intraocular Lenses
Some IOLs are specially designed to absorb light
that can harm the eye. The human eye becomes
more vulnerable to blue light when the natural
crystalline lens of the eye yellows with age.
The blue light blocking IOLs replicates the transmission
ability of the aging crystalline lens and shields
the retinal pigment epithelial cells from blue-light
hazards. This also reduces the risk for a condition
called macular degeneration.
The AcrySof Natural (SN60AT)
This is one such blue blocker adapted to a single-piece
AcrySof and provides higher protection than just
UV rays. Disadvantages of these yellow IOLs are
a probable effect on color and night vision (since
blue light is required more for night than for
The problem of night vision is being addressed
by the SmartYellow IOL. This is a three-piece
lens created from a proprietary hydrophobic acrylic
substance and more importantly has photochromic
properties that can address the problem of night
vision with yellow lenses. Studies have suggested
that its photochromic changes are reversible,
can be replicated and is ensures long-term stability.
Accommodative Intraocular Lenses
IOLs are also designed to restore the accommodation
ability of the eye. The Eyeonics CrystaLens (model
AT45) is created from a third-generation silicone
material (Biosil) with a refractive index of
1.43. It was approved by the FDA in 2003 with
the benefit of estimated addition of 1 D of accommodation
compared to monofocal lenses.
The Synchrony IOL is a one-piece silicone lens
that is based on the conventional Helmholtz’s
theory of accommodation. It is now under clinical
examination. Bausch and Lomb is also currently
developing another single-piece molded silicone
dual-optical accommodating IOL.
Aspheric Intraocular Lenses
Aspheric IOLs correct spherical aberrations
of the human eye. Z-Sharp Optic Technology has
been implemented on the CeeOn Edge IOL, model
911 platform to manufacture Aspheric IOLS. Currently
available IOLs like Tecnis also have positive
The AcrySof aspheric (model SN60WF), adapted
from the single-piece AcrySof, has negative spherical
aberration. Both the Tecnis and the SN60WF lens
offset the average spherical aberration in cataract
The SofPort Advanced Optics (AO) (model LI61AO)
from Bausch and Lomb does not add negative spheric
aberration to the eye, but it is Aberration-free
when compared to the other aspheric IOLs.
Intraocular Lenses For Very Small Incisions
The invention of microincision surgical techniques
that enabled cataract removal through clear corneal
incisions as small as 1 mm, led to the manufacture
of suitable IOLs. One such latest model that
can be inserted through a sub 2-mm incision (1.45-mm)
is the UltraChoice 1.0.
Another new concept of very-small-incision IOLs
called SmartIOL, which can also restore accommodation.
Light Adjustable Lens
Calhoun Vision is developing a three-piece silicone
lens with photosensitive silicone subunits. This
ensures a non-invasive implantation and definitive
refraction to the patient. It also provides correction
of higher-order eye deviations like the tetrafoil
patter and aspheric conditions, besides hyperopic,
myopic, and astigmatic therapy.
Implantable Miniature Telescope
The implantable miniature telescope is an exclusive
visual prosthetic gadget that addresses advanced
stage age-related macular degeneration. It is
developed by VisionCare Ophthalmic Technologies
and has the additional feature of ensuring a
natural cosmetic look. Another model of the telescope
is being adapted for pseudophakic cases.