"Staining the anterior capsule during cataract surgery does not appear to reduce YAG capsulotomy rates," said Dr Antonis Ioannides (Manchester University Hospitals NHS Trust, Manchester, UK) when describing the findings of his recent study at the 2011 annual ESCRS congress in Vienna, Austria.

Dr Ioannides and colleagues investigated whether trypan blue 0.06% staining of the anterior capsule during cataract surgery would decrease the rate of, or time to, YAG posterior capsulotomy in a retrospective chart review of 93 patients. "Previous studies did not examine the direct effect of trypan blue on posterior capsule opacification (PCO) or YAG capsulotomy but have shown that trypan blue affects the viability and/or proliferation of lens epithelial cells (LECs)," explained Dr Ioannides. "This would only infer that trypan blue may reduce PCO or YAG capsulotomy rates, which was not supported by the findings of our study."

In describing the reasoning behind the study Dr Ioannides noted that PCO is a common late postop complication of cataract surgery and current treatment may lead to other complications. Therefore, alternative ways of reducing the rate of PCO are important. "Previous studies have identified factors that can potentially modulate the development of PCO including surgical technique as well as intraocular lens (IOL) geometry and material," he added. "We wanted to examine whether staining the anterior capsule with trypan blue before capsulorrhexis as used in cataract surgery reduces the rate of Nd:YAG posterior capsulotomy compared to that of unstained capsules because of reduced incidence of visually significant PCO."

The study

The study included 183 eyes of 93 patients who had undergone bilateral phacoemulsification and implantation of the same IOL type in both eyes within a 7 year period (between 2000 and 2007). Trypan blue 0.06% staining of the anterior capsule prior to capsulorhexis was performed unilaterally and the contralateral eye was used as the control.

Each patient was advised to request a followup appointment if any postop visual symptoms were experienced and if these symptoms were characteristic of PCO then YAG capulotomy was performed. The endpoint was considered to be the period between surgery and YAG capsulotomy and if a patient did not undergo YAG capsulotomy by January 2011 they were considered to not present with visually significant PCO. The mean followup period was 50.4 months.

No difference found

"It is believed that posterior migration of lens epithelial cells (LEC) that persist after cataract surgery is critical in the pathophysiology of acquired PCO," added Dr Ioannides. "Recently, Portes et al. ¹ demonstrated that trypan blue staining of the anterior capsule in cataract surgery causes LEC death. This was not observed on unstained capsules. We were, therefore, expecting to find an association between the use of trypan blue and reduced YAG posterior capsulotomy rate."

No statistically significant difference was found between the trypan blue eyes and the control eyes for either postop bestcorrected visual acuity (BCVA) , significant difference in the YAG capsulotomy rate or the time to develop clinically significant PCO. "A possible explanation could be that either the concentration of trypan blue as used in our study (0.06%) or its exposure time to the anterior capsule before washout was inadequate to affect viability, proliferation or migration of LEC at a clinically significant level," said Dr Ioannides.

Special contributor

Dr Antonis Ioannides is a cataract surgery fellow at Manchester University Hospitals NHS Trust, Manchester, UK. The study discussed in this paper was performed at the Mid Yorkshire Hospitals NHS Trust, UK. He may be reached by Email: antonis@antonis.org

Dr Ioannides has indicated no financial disclosures.

Reference

1. A.L.F. Portes et al., J. Cataract Refract. Surg., 2010; 36(4):582–587.