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Trypan blue injected into capsular bag markedly reduces postop PCO
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An injection of trypan blue into the capsular bag significantly reduced posterior capsule opacification in eyes undergoing phacoemulsification and foldable hydrophilic acrylic IOL implantation, according to a study.
Previous studies showed that trypan blue used for staining the outer surface of the anterior capsule eliminated proliferative and transformative lens epithelial cells (LECs), the primary cause of PCO. The authors set out to gauge the effect of trypan blue injected into the capsular bag rather than the anterior capsule.
“[The] most significant finding was the decrease in PCO scores,” Pankaj Sharma, MD, the corresponding author, said in an email interview. “The actual biochemical effect of trypan blue on LECs needs to be studied. Our hypothesis is based on previous studies where trypan blue was used for a different purpose and PCO rates were not studied. Also, the method of use was totally different in previous studies.”
The study was published in the Journal of Cataract and Refractive Surgery.
Patients and methods
The prospective, randomized study included 300 eyes; 150 eyes were injected with 0.2 mL of trypan blue 0.1% and a control group comprised 150 eyes that were injected with 0.2 mL of balanced salt solution. Dye or balanced salt solution was injected subcapsularly at two sites 180° apart after cortical-cleaving hydrodissection.
Corrected distance visual acuity and slit lamp examinations were assessed at 1 and 7 days, and at 1, 6 and 12 months. Anterior segment photographs under full mydriasis were taken at 6 and 12 months. All eyes were dilated to assess residual staining of the capsule and other intraocular structures 1 day after surgery.
A masked observer assessed PCO in each group.
“LECs were not imaged directly, but only the PCO score was calculated. This was an indirect effect of LEC lysis, since proliferating LECs are the major cause of PCO in modern cataract surgery,” Sharma said.
Final data were analyzed for 102 eyes in the trypan blue group and 103 eyes in the comparator group.
“Patient selection was very important, as we excluded all cases where there was a chance of increased PCO (young age, uveitis, trauma, etc.),” Sharma said.
Outcomes and observations
Mean PCO scores were 0.10 in the trypan blue group and 0.21 in the control group at 6 months; the between-group difference was statistically significant (P = .042). At 12 months, PCO scores were 0.15 in the trypan blue group and 0.25 in the control group, and again the difference was considered significant (P = .0227).
Two eyes in the trypan blue group and six eyes in the control group required YAG capsulotomy.
“There was a higher YAG capsulotomy rate in the non-treated group, but it was not statistically significant,” Sharma said.
Mean corrected distance visual acuity was 0.04 in the trypan blue group and 0.07 in the control group; the difference was insignificant, the authors said. – by Matt Hasson