High water content hydrophilic acrylic IOL gets the blues

By Roibeard O'hEineachain

Paris - Hydrophilic acrylic IOLs with very high water content may be contra-indicated in eyes where trypan blue staining has been used to facilitate performance of an anterior capsulorhexis, according to an ophthalmologist based at the Storm Eye Institute, Charleston, South Carolina, USA.

A 79-year-old man who underwent trypan blue-assisted implantation of an Acqua™ IOL (Mediphacos, Belo Horizonte, MG, Brazil) required explantation of the lens two months later because of serious visual symptoms partially caused by lens decentration .

The patient complained of "dark and double" vision and "dark blue halos" which developed seven days after the cataract procedure, according to Liliana Werner MD, PhD. She was speaking at the Congress of the French Society of Ophthalmology.

The surgeon had injected the patient's anterior chamber with a 0.1% trypan blue solution prior to capsulorhexis surgery to enhance the contrast between the capsule and surrounding tissues. The lens he implanted is composed of a proprietary copolymer hydrophilic acrylic material (Acryfil CQ) with a bonded UV absorber.

This very interesting IOL is designed for insertion in a dry state when it can fit through a very small incision. Once implanted, the lens undergoes hydration and expansion within the capsular bag whereupon it achieves a water content of 73.5%.

When Dr Werner and her associates received the explanted IOL in a re-dried state, it had a dark blue colouration and the staining was denser within the optic component, especially in the optical periphery. They also found that it retained its blue colouration even after they re-hydrated the lens by immersion in BSS at 37°C for 24 hours.

As an additional experiment, they immersed two new Acqua™ lenses for 24 hours in 0.01% trypan blue (diluted 10 times), and -0.001% trypan blue (diluted 100 times). They found that the lens acquired a blue colouration even at the weaker solution. (See the Journal of Refractive Surgery 2002; VII).

Dr Werner said that her findings indicated that the Acqua lens should not be implanted in eyes where trypan blue has been used during cataract surgery explantation. She noted, however, that other patients who had received the IOL after trypan blue staining of the capsule had also developed blue colouring in their lens although they did not develop visual symptoms and did not undergo explantation of the lens.

"Further investigation will be necessary to determine whether there is any interaction of the Acqua™ lens with other capsular dyes.

"It is also important to investigate whether blue staining is observed only with lenses manufactured from biomaterials having very high water content and/or those which depend on the fluids within the bag for complete hydration and expansion, or whether it might be observed in association with hydrophilic lenses in general," Dr Werner said.

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