Purchase this article with an account.
Georg Schuele, Daniel V. Palanker, Neil Friedman; Capsular strength and ultrastructural appearance of Femtosecond Laser Capsulotomy and Manual Capsulorhexis. Invest. Ophthalmol. Vis. Sci. 2011;52(14):5704.
Download citation file:
© ARVO (1962-2015); The Authors (2016-present)
To evaluate the ultrastructural appearance of the capsular edge and its rupture strength in capsules cut by two different techniques: traditional manual capsulorhexis and femtosecond laser capsulotomy.
Samples and preparation: After the cornea and iris in porcine eyes were surgically removed (n=46, less than 24 h post enucleation), 13 manual and 33 laser capsulotomies of 4.6mm in diameter were created. Laser pulse energies ranged from 3 to 10uJ. The lens cortex and the nucleus were then completely removed by standard ultrasonic phacoemulsification. For the capsular stretching experiments the empty capsular bags were refilled using a low viscosity liquid containing 0.05% gelatin. The eye was mounted on an X/Y/Z translation stage such that two symmetrical half-cylinder stretching pins with 2 mm radius of curvature fit into the capsular opening. The pins were then symmetrically pulled apart and the force on both pins was recorded. Strength was measured as the maximum force exerted on the capsule until it tore. For SEM imaging the excised capsular samples were fixed in formalin.
The rupture strength was determined in each of the manual and lasered eyes. Depending on pulse energy the laser created capsulotomies had about two to three fold higher break force (152±21mN for 3uJ, 121±16mN for 6uJ, 113±23mN for 10uJ) compared to those created by the manual technique (65±21mN). All results were statistically significant with a t-test p < 0.05. SEM analysis of the laser capsulotomy edges (Figure 1) revealed microgrooves spaced by 5 um, which corresponds to the laser spot spacing.
Femtosecond laser capsulotomy provides a stronger edge than a manual capsulorhexis. This is an important safety aspect that may reduce the risk of capsular ruptures during cataract surgery.
This PDF is available to Subscribers Only