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Marred by reports of vision loss due to contamination, amongst other complications, trypan blue has received its fair share of bad press over recent years, with many unapproved versions of the formulation making its way into cataract surgeons' practices.
With only one FDA approved version of the staining solution currently on the market (VisionBlue; DORC International b.v.), rumours of complications associated with use of trypan blue have, naturally, had an impact on the way surgeons now view VisionBlue. But what is the real problem with the solution? Is there a problem at all?
After its introduction in 1999, VisionBlue was quickly recognized by ophthalmic surgeons as one of the most significant innovations in cataract surgery since the advent of viscoelastics. The intraoperative use of the dye greatly enhanced the visibility of intraocular tissue structures, in particular the anterior lens capsule. Providing contrast, VisionBlue enabled surgeons to better visualize the leading edge of the capsulorhexis, so that surgical manoeuvres were far better controlled and inadvertent radial tears were quickly noted. Capsulorhexis related complications dropped dramatically so that the use of VisionBlue greatly improved the safety of performing cataract surgery. So far, no adverse effects have been observed and, considering its proven record of safety, it was approved by the FDA as a drug without repetition of clinical studies.
With any unauthorised product, you know that you are always taking a risk. Serious problems may sometimes ensue, some may be reported and some may not. "There is a point at which you need to realise that the approval process is there for a reason. What's surprising is the level of detail required for the production and ultimate approval of a drug," said Gerrit Melles, MD, of the Netherlands Institute for Innovative Ocular Surgery and inventor of VisionBlue.
Indeed, reports of unapproved pharmacy versions of the dye being linked with Pseudomonas aeruginosa (a worrying cause of endophthalmitis) and subsequent vision loss, led to an emergency recall of certain batches throughout the US in 2005. Because the exact cause of contamination was not fully established, rumours did cause many ophthalmologists to question the safety of all trypan blue formulations. Melles conceded, "This backfired on VisionBlue, to some extent, although most surgeons realize that it was not linked to these events."
During trials with the product, Dr Melles reviewed all reports on adverse effects but none of the reports could be directly linked to the intraoperative use of trypan blue. "VisionBlue is now routinely used in cataract surgery and, in particular in complicated cases, for example in white cataract surgery. White cataracts are traditionally more prone to complications because of the uncontrolled forces that act within the lens capsule, for example an uncontrolled extension of the capsulorhexis in the presence of an overhydrated crystalline lens. Given the number of cataract surgeries performed, the lack of serious adverse events seems to support the safety of our drug formulation," he explained.