Abstract
Purpose: :
Trypan blue currently remains the most preferred dye to stain the anterior capsule while performing a capsulorhexis during cataract surgery in cases with compromised red reflex. There are some anecdotal reports that the trypan blue staining weakens the lens capsule, and consequently less force is required to tear the capsule. The purpose of this experimental study was undertaken to evaluate a potential weakening effect of trypan blue dye on the anterior capsule.
Methods: :
Eight freshly obtained, paired postmortem human eyes were included in this study. An anterior capsulorhexis, of about 4 mm in diameter, was performed using a 30–gauge needle and Utrata capsulorhexis forceps (Ellis Ophthalmic Technologies, Inc, Jamaica, New York). A total of 4 eyes were used as control and another 4 eyes were stained with trypan blue (0.06 percent solution, DORC International b.v. [Vn Zuidland, Netherlands]) for about 30 seconds. In each pair of eyes from a single donor, one eye was stained and the other served as a control. Unstretched and stretched measurements of the capsule opening were then performed in each group using dial calipers (Chicago Brand Industrial, Inc, Fremont, California). The percentage change in the capsulorhexis circumference on stretching was calculated for each eye using the formula: R = (stretched/unstretched) × 100%.
Results: :
There was no statistically significant difference in the unstretched and stretched capsulorhexis diameter in both groups. Mean capsulorhexis diameter was 3.83 mm in control group (range 3.8 to 4.0 mm); and 4.0 (range 3.8 to 4.25) mm in trypan blue group. Mean stretched capsulorhexis diameter in control and trypan blue group were 10.5 (10.3 to 10.8) mm; and 10. 17 (range 8.4 to 12) mm, respectively. Mean percentage of stretched capsulorhexis circumference in control, and trypan blue group measured as 194.65%, and 192.6% respectively. This difference was not statistically significant (p = 0.8, paired t test).
Conclusions: :
Results of this pilot study suggest that trypan blue does not weaken the anterior capsule. This was evident by the fact that there was no significant difference in the stretchability of the capsulorhexis opening with or without trypan blue. This is consistent with clinical experience. Further quantitative studies are in progress to generate conclusive data.
Keywords: cataract • clinical laboratory testing