COMPLICATIONS WITH TRYPAN BLUE

CHERYL GUTTMAN KRADER REPORTS

The likelihood of an anterior capsule (AC) tear during phacoemulsification cataract surgery is significantly higher in cases using trypan blue for AC staining, according to a large retrospective review. It also found AC tear development is associated with a significantly increased rate of posterior capsule (PC) tear with vitreous loss.

Alexander Ionides MD reported the findings, which analysed electronic phacoemulsification cataract surgery records from a large, multicentre NHS teaching hospital trust. The researchers identified 140,930 cases of phacoemulsification performed from January 2011 to January 2021. Trypan blue was used in 1,541 (1.1%) of the 140,930 cases.

The tear occurred in 98 (6.4%) of the 1,541 cases performed with trypan blue and 1,756 (1.3%) of the 139,391 cases where the stain was not. Comparing the trypan blue group with and the group without, the 5-fold increase in AC tear rate in the former group was highly statistically significant (P <.0001).

Researchers concluded having absolute numbers regarding AC and PC tears allows surgeons to have more accurate data to provide to patients when obtaining informed consent for phacoemulsification. Dr Ionides acknowledged, however, several limitations, including the potential for selection bias and those inherent to a retrospective design.

“There may be many reasons for our finding, including trypan blue was perhaps used in more complicated cases with an increased risk of a complication anyway. [It’s also] a retrospective electronic database study. Therefore, it relies on accurate data entry and all the problems that can entail.”

Dr Ionides and colleagues Drs Osvaldo Berger and Benjamin Riley were interested in investigating whether intraoperative use of trypan blue affected the AC tear rate based on anecdotal impressions the stain affects the material properties of the anterior capsule.

“Some surgeons feel trypan blue alters the elasticity of the anterior capsule, while basic science laboratory studies have conflicting findings. We wondered if the anterior capsule stained with trypan blue is in fact more brittle and if there was an increased likelihood it would tear,” he explained.

A secondary study objective examined the risk of developing an extension of an anterior capsule tear to the posterior capsule. Data analysis showed the risk of PC tear with vitreous loss was more than 10-fold higher in eyes with an AC tear compared to those without (P <.0001).

Within the entire case series, 2,231 eyes developed a posterior capsule tear with vitreous loss. The PC tear subgroup comprised 246 (14.0%) of the 1,754 eyes with an AC tear and 1,985 (1.3%) of the 139,078 eyes without an AC tear.