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Assessing the consistency of a pre-loaded IOL injection system

Session Details

Session Title: Corneal Incisions and preloaded IOLs

Session Date/Time: Sunday 06/10/2013 | 08:00-09:30

Paper Time: 09:02

Venue: Elicium 2 (First Floor)

First Author: : N.Nathoo CANADA

Co Author(s): :    P. Faber   B. Toosi           

Abstract Details


Foldable intra-ocular lenses (IOLs) have become an integral part of modern-day cataract surgery. The deformable nature of the lens allows it to be folded in an injector and inserted into the eye through a smaller incision. Although metal injectors into which the lens is loaded intra-operatively are sometimes used, one-time use sterile injectors with pre-loaded lenses, which were introduced in 2002, are gaining popularity as they eliminate the labor for sterilization and also enhance intra-operative efficiency and consistency. However, we have observed that results using the pre-loaded systems are not always consistent. In many cases the injected IOLs differ in orientation and are not delivered straight. While there are studies that compare the resulting IOL lens roughness during cataract surgery between manual loading and preloaded IOL systems (7), however there is limited literature describing the consistency of IOL injections using pre-loaded systems. Our objective is to examine the consistency of the orientation of the IOLs using a preloaded system and investigate the relationship of orientation to the IOL power.


Single surgeon’s academic practice


Prospective review of all pre-loaded IOLs used by a single surgeon for twelve consecutive days of cataract surgeries. Lens information was gathered during the course of routine cataract surgery, but no change to the surgery procedure was made and no patient information was recorded. Lens power was recorded, along with a note of whether the lens was delivered from the injector ‘straight’ (leading haptic and lens correctly folded and delivered inside the injector) or ‘twisted’ (leading haptic unfurled, with the resulting lens delivered in a twisted manner). Descriptive statistics were used to describe the data, and Student’s unpaired t-test was used to compare the two groups (straight and twisted). This study was deemed not to require Institutional Ethics Board approval as per the UBC Health Research Ethics Board guidelines.


A total of 144 pre-loaded IOLs were used over the course of twelve consecutive days of cataract surgery, with a range of lens powers from 9.0 to 28.5. Of all the lenses delivered, 38.2% came out of the injector twisted. Twisted lenses were of higher power (mean 20.94, median 21.0) compared to those delivered straight (mean 19.89, median 20.5); this difference was significant (p=0.0461).


Pre-loaded IOLs have a huge variability in how the lenses are delivered, and cannot be assumed to be standardized. While experienced surgeons who have used pre-loaded IOLs extensively are likely accustomed to the unpredictability of their delivery, surgeons who are new to them (including trainees) should be aware of their variability so as to be able to control for it during their IOL injection; while this variability is greater for higher powered lenses, it is certainly present at all lens powers and should be accounted for.

Financial Interest:


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