Comparison of capsulorhexis resistance to tearing with and without trypan blue dye using a mechanized tensile strength model.

Purpose: To evaluate the influence of trypan blue staining on capsulorhexis tear resistance using a model for mechanical measurement of the entire capsular bag of fresh human cadaver eyes.

Setting: John A. Moran Eye Center, University of Utah, Salt Lake City, Utah, USA.

Design: Experimental study.

Methods: After the cornea and iris were removed, a 5.0 to 5.5 mm anterior continuous curvilinear capsulorhexis (CCC) was created; the capsule in study eyes was stained with trypan blue. The nucleus was hydroexpressed and the capsular bag was evacuated by irrigation/aspiration. Two metal shoetree-shaped fixtures were implanted separately in the capsular bag and assembled using a screw nut. After zonulectomy, the fixture-capsular bag assembly was removed from the eye and loaded onto a mechanized tester. The fixtures were separated at a velocity of 7.0 mm/min in 0.15 μm intervals to stretch the capsulorhexis to its rupture point. A graph was generated for each eye.

Results: Ten study eyes were compared with 23 control eyes. The groups were comparable in donor age, time from death, and CCC diameter. The mean rupture load was 0.40 Newton (N) ± 0.13 (SD) in the trypan blue group and 0.39 ± 0.16 N in the control group (P=.94). The mean extension was 5.70 ± 0.99 mm and 5.85 ± 1.17 mm, respectively (P=.74).

Conclusions: There was no difference in CCC strength between trypan blue-stained capsules and control capsules. Staining with trypan blue did not reduce CCC tear resistance.

Financial Disclosure: No author has a financial or proprietary interest in any material or method mentioned.