Refractive Lens Surgery

Fig. 8.2. AcrySof toric
IOL implanted into
the eye. (Courtesy
of Stephen Lane, MD)
an unfavorable environment for cell proliferation
[8]. In addition to this biomaterial adhesive
property being effective at aiding in
the reduction of PCO, it may also account for
the exceptional rotational stability necessary
for a successful toric IOL.
The second feature of the AcrySof toric IOL
that increases its ability to maintain a clear
posterior capsule and ultimately reduces the
need for a Nd:YAG capsulotomy is the design
of the posterior optic edge [8, 9]. Nishi et al.
demonstrated in an animal study that the
sharp-edged optic design of the AcrySof IOL
incorporates a PCO-reducing effect [10].
Proven in a separate study, the AcrySof IOL’s
square truncated optic edge created a barrier
to migration of lens epithelial cells,leaving the
visual axis clear of PCO [8].
The stable-force haptics are another beneficial
design attribute of the AcrySof toric
IOL. These haptics are designed for maximum
conformance to the capsular bag, offering
the greatest possible surface area for adherence
between the IOL and the capsular
tissue. This in turn leads to greater stability of
the IOL, and to a pronounced “shrink-wrap”
effect (Fig. 8.2), which takes place during the
early postoperative time course. It is this
Chapter 8 Correction of Keratometric Astigmatism 73
property that is likely responsible for “locking”
the lens in place.
In essence, the AcrySof single-piece IOL
platform provides the ideal material and design
features for a toric IOL. The soft acrylic
material allows for small-incision surgery, the
natural PCO reduction characteristics allow
for fewer postoperative complications, and
the adhesion and capsular bag conformance
properties allow for highly stable and predictable
positioning of the IOL.
8.2 Surgical Procedure
Implantation of the AcrySof toric IOL implantation
follows a similar procedure as that
of most modern small-incision cataract surgeries,
using phacoemulsification and in-thebag
IOL placement. Extra corneal marking
steps are included to ensure proper positioning
of the toric correction. To account for cyclorotation,
the cornea is marked at the 3 and
9 o’clock limbus while the patient is in an upright
position. Once the patient is positioned
for surgery,a Dell astigmatism marker is used
to mark the axis of the steep corneal meridian
using the previously placed 3 and 9 o’clock