Modern anterior chamber IOLs still have

Still a place for the anterior chamber IOL

Careful patient selection and rigorous surgery key to success with modern AC IOLs. Dermot McGrath reports

Although they have a chequered history and a mixed reputation among cataract surgeons, anterior chamber intraocular lenses (AC IOLs) may still be a viable option in carefully selected patients with minimal or no capsular support, according to Richard Packard MD, FRCOphth.

“The advantage for many surgeons in implanting AC IOLs in cases with lack of capsular support is that it is a relatively straightforward technique and can be completed fairly quickly. While there will inevitably be some endothelial cell loss, it is usually manageable and the benefits may outweigh the risks for older patients who might not be able to tolerate a longer operative time,” Dr Packard said at the World Ophthalmology Congress 2020 Virtual.

BAD REPUTATION In a broad overview of the complications associated with AC IOLs, Dr Packard noted that these lenses understandably received a bad reputation dating back to their initial use by Harold Ridley in the 1950s.

“Harold Ridley found that the posterior chamber IOL was unstable, so he and others moved to the anterior chamber. The most popular design, the Strampelli lens, was widely implanted but the results were not very good. As early as 1956 Hallermann stated that corneal degeneration was a severe complication of angle-fixed IOLs and Nordholm in 1975 reported that Barraquer had to remove 250 of 493 AC IOLs implanted. Bob Drews in 1979 was able to examine half of these explanted IOLs and found them to be rough and poorly manufactured,” said Dr Packard.

Some of the common complications associated with the early anterior chamber intraocular lenses included reduced corneal endothelial cell count leading to corneal decompensation, glaucoma related to angle obstruction or distortion, dislocation of the implant and chronic uveitis.

“These disasters were due to a lack of understanding of lens design and the effect it would have on the corneal anatomy,” said Dr Packard. The IOL manufacturing standards of the day also played a part, with rough edges of the haptics that were in direct contact with the irido-corneal angle, wreaking havoc on the corneal endothelium.

The rigidity of AC IOLs was also deemed to be a factor in promoting corneal damage, which led to a plethora of flexible loop designs, said Dr Packard.

“None of these IOLs stood the test of time except for one – the Kelman Quadraflex, which was then adapted by Charles Kelman into the Multiflex design. This IOL design incorporated many lessons learnt from Peter Choyce, the most important being the correctly sized footplate and that it should be a planoconvex optic for an AC IOL,” he said.

POTENTIAL COMPLICATIONS As well as corneal decompensation, surgeons also need to be vigilant concerning several other potential complications associated with AC IOL implantation, said Dr Packard.

“The list includes uveitis-glaucomahyphema syndrome (UGH), where parts of the vasculature of the anterior and posterior chamber would be eroded by the lens

The advantage for many surgeons in implanting AC IOLs in cases with lack of capsular support is that it is a relatively straightforward technique and can be completed fairly quickly Richard Packard MD, FRCOphth and cause intermittent bleeding and high pressure. Also, if there wasn’t an adequate iridectomy or iridotomy, then iris bombe could form around the lens. Iris tuck could also occur, and sometimes the lens was too small which would cause considerable erosion of endothelial cells,” he said.

The scientific literature on the use of modern-design AC IOLs lends credence to their safety and viability in selected cases, said Dr Packard. For instance, a paper by Kendall Donaldson et al. in 2005 reported that no significant differences were found in outcomes comparing AC IOLs to sutured PC IOLs in complicated cataract extraction with poor capsular support.

In 1996, Bellucci et al. reported that scleral-fixated posterior chamber IOLs were associated with more intraoperative and postoperative complications than angle fixated AC IOLs and surgery took longer. They concluded that anterior chamber IOL implantation should be considered for older patients with relatively good endothelial cell counts.

SUCCESSFUL OUTCOMES There are a number of factors involved in obtaining successful outcomes with AC IOLs, said Dr Packard.

“We need devices to measure the white to white and incision size and a good understanding of correct lens sizing with an adequate IOL bank of at least three sizes for each IOL power. We need to recalculate for the correct A constant (115.3). We should also have Miochol or a similar product to constrict the pupil and a Sheets lens glide and cohesive viscoelastic to help implantation. A vitrector is also useful to do an anterior vitrectomy if required and perform an iridectomy. Finally, triamcinolone is helpful to expose any vitreous as part of the anterior chamber clean-up prior to implantation,” he said.

Summing up, Dr Packard said that AC IOLs offer an efficient and straightforward implantation method in compromised eyes and particularly in older patients.

“Provided certain basic rules of measurement and insertion are applied you should be able to get good results and avoid any serious complications,” he concluded.