Segmented Bifocal SBL-3
Presbyopia is a condition that occurs when the eyes natural lens begins to stiffen
and harden with age. This makes it difficult to focus on objects close up and at
intermediate distances. Bifocal and multifocal IOLs are presbyopia-correcting
IOLs that can decrease your need for reading glasses or computer glasses after
cataract surgery. These premium IOLs contain added magnification in different parts
of the lens to expand your range of vision so you can see objects clearly at all
distances without glasses or contact lenses.
Dr. Pandit can help you decide if you are a good candidate for bifocal and
multifocal IOLs at your preoperative exam and consultation.
Any patients with more than 0.5 dioptres of corneal astigmatism after insertion of a
multifocal lens (0.75D after bifocal lens implant) implant may be dissatisfied with the
quality of vision, as there may be glare, photophobia, ghosting and reduced
contrast. Therefore astigmatism must be minimized. Multifocal toric lenses are
suitable for patients who want reduced dependence on glasses for distance and
near, and who have significant regular corneal astigmatism. The lenses are
designed to reduce regular astigmatism in a particular axis of rotation. If you have more than
1 dioptre of regular corneal astigmatism then you should consider a toric
multifocal lens implant.
It is important to remember that visual contrast after insertion of any multifocal lens
will be affected and they may not be suitable for everyone. Also, good distance
vision can be achieved but there will usually be a choice between intermediate or
near vision. Bifocal lens implants have less reduction of contrast than multifocal
Segmented bifocal lens implants give excellent distance and near vision and
reasonable intermediate vision. They are a good choice as they do not require an
extensive period of neural adaptation and can often be implanted in just one eye; it
is not necessary to implant them in both eyes, although there will be a loss of
stereopsis at near vision if that is done.
It is necessary to implant multifocal lenses in both eyes, otherwise, there will be too
big a mismatch between the two eyes for comfortable vision.
Currently, Dr. Pandit recommends segmented bifocal lens implants as giving the
best balance between excellent vision and fewest side-effects. See the animation
above for an explanation of how they work.
An alternative lens implant that works in a completely different way is the IC8 IOL.
This is a small aperture lens implant that works on the pinhole principle. This
means that contrast is not reduced and astigmatismupto 1.5D is not usually a
problem. There is no axis of orientation to worry about. Good vision canachieved
for distance, intermediate and near distances. The lens implant is inserted in only
one eye (instead of two eyes required for multifocal lenses) and that is thenon-
dominant eye. If there is any macular pathology or if the patient is diabetic and may
require pan-retinal photocoagulation at some future date then the IC8 may not be
suitable as the view of the retinal periphery without indentation is limited.