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. 2021 Jul:227:45-52.
doi: 10.1016/j.ajo.2021.02.021. Epub 2021 Feb 22.

A Biomechanical Study of Flanged Intrascleral Haptic Fixation of Three-Piece Intraocular Lenses

Kevin K Ma  1 , Amy Yuan  2 , Sina Sharifi  3 , Roberto Pineda  4
Affiliations

A Biomechanical Study of Flanged Intrascleral Haptic Fixation of Three-Piece Intraocular Lenses

Kevin K Ma et al. Am J Ophthalmol. 2021 Jul.

Abstract

Purpose: Flanged intrascleral haptic fixation (FISHF) is a useful method for securing intraocular lenses (IOLs) in eyes without capsular support. Biomechanical studies were conducted to support the use of this technique.

Design: Laboratory investigation.

Methods: Haptics of 3-piece IOLs were passed through cadaveric human sclera using 30- and 27-gauge needles. Flanges were created by melting 1.0 mm from the haptic ends using cautery. The forces required to remove the flanged haptic from the sclera and disinsert the haptic from the optic were measured using a mechanical tester and a custom-fabricated mount.

Results: The mean FISHF dislocation force using 30-gauge needles was greatest with the CT Lucia 602 (2.04 ± 0.24 newtons [N]) compared to the LI61AO (0.93 ± 0.41 N; P = .001), ZA9003 (0.70 ± 0.34 N; P = <.001), and MA60AC (0.27 ± 0.19 N; P <.001). Using 27-gauge needles with the CT Lucia resulted in a lower dislocation force (0.56 ± 0.36 N; P <.001). The FISHF dislocation force was correlated with the flange-to-needle diameter ratio (r = 0.975). The FISHF dislocation forces of the CT Lucia and LI61AO using 30-gauge needles were not significantly different from their haptic-optic disinsertion forces (P = .79 and .27, respectively). There were no differences in flange diameters between 1.0 mm and 2.0 mm haptic melt lengths across the IOLs (P = .15-.85).

Conclusions: These data strongly support the biomechanical stability of FISHF with the polyvinylidene fluoride haptics of the CT Lucia using small diameter instruments for the creation of an intrascleral tunnel. 1.0 mm of haptic may be the optimal melt length.

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Conflict of interest statement

ALL AUTHORS HAVE COMPLETED AND SUBMITTED THE ICMJE FORM FOR DISCLOSURE OF POTENTIAL CONFLICTS OF INTEREST and none were reported.

Figures

FIGURE 1.
FIGURE 1.
Biomechanical testing experimental setup. A. A custom-made mount with a flanged intrascleral-fixated IOL haptic (superior) and wedge grip securing the IOL optic (inferior) was used to perform flanged intrascleral haptic fixation dislocation experiments. B. A custom-made mount with an IOL optic seated vertically (superior) and wedge grip grasping the inferior haptic (inferior) was used to determine intraocular lens haptic-optic disinsertion force. The opening of the custom mount had a width of 0.9 mm. IOL = intraocular lens.
FIGURE 2.
FIGURE 2.
Flange shapes and diameters after 1.0 mm of IOL haptic melt. A. CT Lucia 602 (flange diameter 0.445 ± 0.015 mm). B. ZA9003 (0.365 ± 0.043 mm). C. LI61AO (0.338 ± 0.023 mm). D. MA60AC (0.306 ± 0.033 mm).
FIGURE 3.
FIGURE 3.
FISHF dislocation force and haptic-optic disinsertion force are given for each intraocular lens model, with error bars representing standard deviations. There were no significant differences (ns) between the FISHF and the haptic-optic forces for the CT Lucia 602 and the LI61AO IOLs with 30-gauge TSK needle scleral tunnels. For the other models, the haptic-optic disinsertion force was greater than their flanged dislocation forces (*P <.05; ***P <.01). FISHF = flanged intrascleral haptic fixation.
FIGURE 4.
FIGURE 4.
A. Correlation of flange-to-needle diameter ratio to FISHF dislocation force. B. Correlation of flange-to-haptic diameter ratio to FISHF dislocation force. FISHF = flanged intrascleral haptic fixation.
See this image and copyright information in PMC

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