Comparison of In-the-bag Stability Between Single-piece and Three-piece Intraocular Lens
Status:
Completed
Trial end date:
2012-12-01
Target enrollment:
Participant gender:
Summary
Rapid advances of cataract surgery techniques and intraocular lens (IOL) technology have
enabled the transition of cataract surgery from blindness relief to refractive correction. An
ideal IOL is the critical component to achieve the refractive target of cataract surgery.
Biocompatibility, rate of posterior capsule opacification (PCO) and visual quality have all
been suggested as the critical factors of an ideal IOL and widely investigated. Recently,
stability of IOL position has also been suggested as one of those critical factors due to its
close correlation with postoperative visual function. Data suggests that IOL forward movement
of 0.29 mm along the visual axis is associated with -0.4D myopic shift. Wang and colleagues
recently reported that 0.5mm decentration of an aspheric IOL could eliminate its
aberration-correcting effect. Poor stability could even lead to IOL exchange, an additional
surgery that put both surgeons and patients in pain.
As the supporting element of an IOL, the haptics are crucial to keep the IOL in place.
Various haptic designs are being compared in terms of position stability of IOLs. Haptic
designs of single-piece versus 3-piece are often compared because they are currently the most
commonly used types. Single-piece IOLs have soft and broader haptics which are made of the
same material as the optic, usually hydrophobic or hydrophilic acrylic, whereas 3-piece IOLs
have rigid haptics which are made of poly methyl methacrylate (PMMA). Clinical studies
comparing these haptic designs have yielded controversial results regarding their position
stability in the capsular bag, which is the most recommended site for IOL fixation in an
uneventful cataract surgery.