Dislocation main reason for IOL explantations, survey finds

Reviewed by Nick Mamalis, MD

Take-home: For 18 years the ASCRS and ESCRS have surveyed their members about the reasons for explantation of intraocular lenses. Looking at the trends and using the information gathered can be helpful in avoiding complications and improving patient outcomes.

The most common complication associated with the explantation of foldable intraocular lenses (IOLs) is lens dislocation or decentration. While glare and visual aberrations are the most common reasons for explanting multifocal lenses.

These observations were the main trends drawn from the “American Society of Cataract and Refractive Surgery/European Society of Cataract and Refractive Surgeons Survey on Foldable IOLs Requiring Explantation or Secondary Intervention.” Nick Mamalis, MD, professor of ophthalmology, University of Utah, Salt Lake City, outlined survey results, which is in its 18^th year.

The survey looks at why the lenses are being explanted and what trends can be seen, and what signs, symptoms, or complaints lead to explantation, or to the exchange of an IOL. What are the actual complications requiring the lens to be removed?

Several types of IOL designs were included:

• one-piece plate lenses;

• one-piece lenses with haptics;

• three-piece lenses;

• multifocal lenses;

• accommodating lenses.

And different types of material:

• silicone;

• acrylic (hydrophobic);

• hydrogel (hydrophilic acrylic;

• collamer.

Dr. Mamalis said there was a broad array of explants reported in the survey. The survey is not intended to say one lens is better than another, but instead to understand why IOLs need to be explanted, and look at trends that emerge to understand further the reasons for explantation of lenses.

Lens type results

Lens type results

In the one-piece plate silicone lenses, which are the original silicone lenses, the most common reason for explantation is dislocation/decentration. There was also some calcification of these lenses in the setting of asteroid hyalosis, especially in patients who have had a YAG laser posterior capsulotomy.

For the three-piece silicone lenses, the most common reason again is dislocation/decentration. Some of these silicone lenses are also calcifying, as  described above, Dr. Mamalis added.

In the one-piece with haptics hydrophobic acrylic lenses, dislocation/decentration is most common, but incorrect lens power is also present. Despite attempts to make better IOL calculations with the latest technology to decrease the incidence of incorrect lens power, dislocation/decentration still was common in the surveys.

Courtesy of Nick Mamalis, MD

In three-piece, hydrophobic acrylic lenses, again dislocation/decentration is most common. This is obviously a common thread in a lot of these lenses. In this particular group, some also showed signs of irritation, iritis, and inflammation.

The one-piece with haptics hydrophilic lens (hydrogel) is different. In this group the most common reason for removal is calcification. This is a different type of calcification from the silicone calcification, which is secondary. These lenses are primarily calcifying, either on or under the surface.

Dr. Mamalis pointed out that glare and visual aberrations in the multifocal lenses were the most common reasons for lens removal. This is different from the complications causing explantation of the other types of lenses.

However, not much difference was found between toric lenses and similar lenses–again, dislocation/decentration. Incorrect lens power also was one of the common reasons why these lenses were explanted.

Reasons for problems

Reasons for problems

When it comes to a reason why dislocation/decentration is the common complication overall, Dr. Mamalis explained that in most cases, the reason can’t be blamed on the IOL. He cited surgical technique or complications.

These often occur in cases where the capsulotomies were not completely intact anteriorly, Dr. Mamalis pointed out. Or the lens may not have been totally in the capsular bag, So the onus is on the surgeon rather than on the IOL.

To avoid complications with foldable IOLs, good surgical technique is essential, Dr. Mamalis said. The implant needs to be completely within the capsular bag, which will decrease the dislocation problem.

Accurate IOL measurements are important so the lenses are not removed because of incorrect lens power.

Glare and optical aberrations are occurring more as reasons for removal of multifocal lenses. Incorrect lens power still is surfacing on occasion. Even though methods of calculating IOL power have improved over the last 18 years of the survey, it still is the third most common reason for IOL explantation.

The numbers of explanted multifocal IOLs are increasing, Dr. Mamalis said. Surgeons are using more of them, so there are more potential complications that cause removal. Hydrophilic acrylic lens removals are declining, as are the silicone plate lenses, because in the United States, they are not being used as often as in the past.

Proper patient selection also is important for multifocal lenses to avoid the reasons for those lenses being explanted, he added.

Explantation of accommodating lenses are beginning to appear in the survey results, but the numbers are small to make any conclusions. 

This is an ongoing survey. Surgeons interested in participating in the survey can find more information on the ASCRS (www.ascrs.org) or ESCRS (www.escrs.org) websites.

Nick Mamalis, MD

E: nick.mamalis@hsc.utah.edu

This article was adapted from a presentation that Dr. Mamalis delivered at the 2016 American Academy of Ophthalmology meeting. Dr. Mamalis had no relevant financial disclosures to report in regard to this subject matter.