keratoconus and pellucid marginal degeneration and in postpenetrating keratoplasty
astigmatism.^9 ,^10 ,^11 There are several specific requirements for the IOLs aimed to
treat astigmatism; the lens has to be easy to manipulate in the capsular bag in order
to achieve good alignment, needs good long-term positional stability, and has to
have as low as possible induction of capsular shrinkage. Toric IOL, which has to be
produced for each individual case, has a line mark on its surface for proper
alignment in the capsular bag. The individual axis of astigmatism is marked with
a pen marker on a patient’s eye preoperatively, in a seated position on a slit lamp;
during the surgery, the line mark on a toric IOL has to be aligned with a pen mark
(Fig. 3 ). Axis of astigmatism has to be determined and marked in a seating position
due to cyclotorzional movement of the eye while a patient is lying down for the
surgery. Proper alignment of toric IOL during surgery is crucial since misalignment
of only 10leads to a loss of 1/3 of the astigmatic correction. Moreover, even a
small decentration of IOL of less than 1 mm will also induce aberrations and poorer
visual result.^12 Typical postoperative appearances of properly aligned multifocal
toric IOL implanted bilaterally in a 56-year-old patient is presented in Fig. 4 ,
correcting patient’s vision in both eyes to 100 % distance, intermediate, and near
visions without any spectacles. Potential problem with toric IOLs is postoperative
movement of the lens inside the capsular bag since the lens will lose its ability to
correct astigmatism if the lens moves “off the axis.” Shrinkage of the capsular bag
may also lead to decentration of the lens and thus have negative impact on its proper
alignment. Misaligned toric intraocular lens has to be repositioned into its proper
position by surgical revision. If surgical correction is needed, the intervention
Fig. 3Preoperative
marking of the axis of
astigmatism is done with a
pen marker on a patient’s
eye while patient is still in
seating position; during the
surgery the line-mark on the
lens has to be aligned with a
pen mark
(^9) Parikakis et al. ( 2013 ).
(^10) Zvornicanin et al. ( 2014 ).
(^11) Wade et al. ( 2014 ).
(^12) Pe ́rez-Vives et al. (2014b).
236 I. Dekaris et al.