Roberto Bellucci MD,FEBOS-CR
Eyes implanted with any type of phakic intraocular lenses (IOLs) require follow-up visits to monitor for possible damage to the corneal endothelium, said Roberto Bellucci MD,FEBOS-CR, Verona, Italy
“Endothelial damage was demonstrated early in the history of phakic IOLs, but the reasons for the damage is still debated,” he told the 24th Winter meeting of the ESCRS in Marrakech, Morocco.
Dr Bellucci noted that corneal endothelial cell loss has been the reason for the withdrawal from the market of all angle-supported phakic IOLs. The Baikoff lens had on average a surgically induced endothelial cell loss of 3%, followed by an annual cell loss of 1-2%. That compares to a normal physiological loss of 0.6% cells per year in adults.
Still worse endothelial damage occurred with the foldable Icare anterior chamber phakic IOL lens, which induced 7-14% annual endothelial cell loss. More recently, Alcon withdrew the Cachet anterior chamber phakic IOL because of abnormally high endothelial cell loss in a small number of patients.
The iris-fixated and posterior chamber phakic IOLs can also induce endothelial cell loss. In the case of iris-fixated IOLs, the reported annual endothelial cell loss has ranged from 0.6-2%, with generally somewhat worse results with the Artiflex than with the Artisan lens. The reported annual endothelial cell loss following implantation ICL and iPCL posterior chamber phakic IOLs ranges from 1% to 1.5%.
Research shows a correlation between postoperative endothelial cell loss and proximity of phakic IOLs to the endothelium. A study conducted in 2010 showed that in eyes where the distance between the lens to the endothelium was 1.2mm the annual rate of cell loss was 1.7% That compared to 0.2% annual loss when the distance was 1.66mm.
There is also a growing body of evidence suggesting that aqueous humour stream is impaired by phakic IOLs, especially during non-REM sleep, depriving in the endothelium of glucose.
Several papers from Spain and from other countries have been published on this topic. These models might explain why the largest AC IOL – the I-Care from France – proved to be the worst as for corneal endothelium preservation.
When to explant?
The AAO currently recommends that phakic IOLs should be explanted when there is 25% cell loss after three years. Research suggests that 1-to-3% of eyes with the Artisan/Verisyse lens implanted and 3% of eyes with the Artiflex fit into this category.
In eyes where the cornea is no longer transparent, endothelial grafts are necessary. Although good results can be achieved leaving the phakic lens in place, Dr Bellucci said that he prefers to remove the lens and perform a triple procedure with crystalline lens extraction and IOL implantation.
