In 1999, we described the use of a vital dye, trypan blue, for staining the anterior lens capsule to facilitate the visualization of the capsulorhexis in cataract surgery.1 At 1 year, the first group of 30 patients showed no ocular or systemic side effects (K.A. van Overdam, MD, “One Year Follow-up After Trypan Blue Capsule Staining in Mature Cataract Surgery,” presented at the XVIIIth Congress of the European Society of Cataract and Refractive Surgeons, Brussels, Belgium, September 2000). To our knowledge, no adverse effects related to the use of the dye have been reported.
Trypan blue 0.3% is widely used as an exclusion dye to determine the viability of the endothelial cell layer of donor corneas prior to transplantation.2 It may therefore seem unlikely that trypan blue 0.06% would have a toxic effect on the corneal endothelium in the living eye when used during surgery. However, to our knowledge, a quantitative evaluation of the biocompatibility of trypan blue with the corneal endothelium has not been performed.
The purpose of our study was to quantitate the endothelial cell damage induced by trypan blue capsule staining by comparing endothelial cell densities between both eyes of patients after bilateral phacoemulsification with or without trypan blue capsule staining, by the same surgeon, using the same surgical technique.
Patients and Methods
Twenty-five patients with bilateral submature cataract in whom the use of capsule dye was relatively indicated were enrolled in the study after an institutional-review-board-approved informed consent was obtained. The mean age of the 8 men and 17 women was 72.7 years ± 9.2 (SD). Exclusion criteria were uncontrolled glaucoma, uveitis, and diabetic retinopathy. Patients were scheduled for bilateral phacoemulsification by the same surgeon within 4 months. One eye of each patient was randomly selected for intraoperative use of trypan blue.
In each eye, a scleral tunnel incision was made and aqueous was exchanged with air. Trypan blue 0.06% (Vision Blue®) was applied on the anterior lens capsule. After a few seconds, the anterior chamber was thoroughly irrigated with balanced salt solution to wash out the excess dye. In the contralateral eye, the anterior chamber was filled with air and then irrigated with balanced salt solution, without application of the dye. After irrigation, the air in the anterior chamber was exchanged with viscoelastic material and the procedure was continued as routine phacoemulsification using a bimanual divide-and-conquer technique, with the implantation of an intraocular lens.3
Before and 12 months after the second surgery, 3 images of the endothelial cell layer were obtained from the central cornea in both eyes (Topcon SP2000p noncontact specular microscope) and analyzed (Imagenet 2000 software, Topcon Corp.). Digital images were manually corrected in a masked fashion to better define the cell border configurations. Outcome parameters were endothelial cell density, coefficient of variation of cell size, cell hexagonality, and pachymetry.
In each eye, the loss of endothelial cell density was calculated by subtracting the mean 12-month postoperative value from the mean preoperative value. The differences in the coefficient of variation, hexagonality, and pachymetry readings were calculated similarly.
Statistical analysis was performed using the paired Student t test, repeated-measures analysis of variance, and the Wilcoxon signed rank test.
At 12 months, the mean postoperative endothelial cell loss was 167 ± 188 cells/mm2 (−7.3%) in eyes operated on with the use of trypan blue and 266 ± 278 cells/mm2 (−10.2%) in the control eyes (P ≥ .1). The preoperative endothelial cell densities were 2561 ± 376 cells/mm2 and 2593 ± 377 cells/mm2, respectively (P ≥ .1). The difference in the coefficient of variation of cell size, cell hexagonality, and pachymetry did not differ between the groups (P ≥ .1).
At 1 year, the mean best corrected visual acuity was 0.8 ± 0.2 in the trypan blue eyes and 0.8 ± 0.3 in the control eyes (P ≥ .1). Three patients had bilateral symmetric, mild atrophic, age-related macular degeneration. All eyes were quiet, and the intraocular pressure was normal.
In our study, no mid-term endothelial cell damage was induced by the intraoperative use of trypan blue for staining the anterior lens capsule. This finding may agree with the clinical observation that no corneal edema is induced by intraoperative use of the dye.1 The overall 7% to 11% endothelial cell loss is similar to that reported after phacoemulsification.4
Bart T.H. van Dooren MD
Peter W.T. de Waard MD
Hester Poort-van Nouhuys MD
Houdijn W. Beekhuis MD
Gerrit R.J. Melles MD, PhD
aRotterdam, The Netherlands
*Dr. Melles has a proprietary and financial interest in Vision Blue.
1. Melles GRJ, De Waard PWT, Pameyer JH, et al. Trypan blue capsule staining to visualize the capsulorhexis in cataract surgery. J Cataract Refract Surg 1999; 25:7-9
2. Sperling S. Evaluation of the endothelium of human donor corneas by induced dilation of intercellular spaces and trypan blue. Graefes Arch Clin Exp Ophthalmol 1986; 224:428-443
3. Gimbel HV. Divide and conquer nucleofractis phacoemulsification: development and variations. J Cataract Refract Surg 1991; 17:281-291
4. Ventura AC, Wälti R, Böhnke M. Corneal thickness and endothelial density before and after cataract surgery. Br J Ophthalmol 2001; 85:18-20