June 2017
Volume 58, Issue 8
Open Access
ARVO Annual Meeting Abstract  |   June 2017
Segmental scleral buckling of eyes with thinned corneas can cause the cornea to tilt
Author Affiliations & Notes
  • Thomas R Friberg
    Ophthalmology/UPMC Eye Center, Univ of Pittsburgh, Pittsburgh, Pennsylvania, United States
  • Raed Aldhafeeri
    Mechanical Engineering, University of Pittsburgh, Pittsburgh, Pennsylvania, United States
  • Patrick Smolinski
    Mechanical Engineering, University of Pittsburgh, Pittsburgh, Pennsylvania, United States
  • Footnotes
    Commercial Relationships   Thomas Friberg, None; Raed Aldhafeeri, None; Patrick Smolinski, None
  • Footnotes
    Support  None
Investigative Ophthalmology & Visual Science June 2017, Vol.58, 4161. doi:
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      Thomas R Friberg, Raed Aldhafeeri, Patrick Smolinski; Segmental scleral buckling of eyes with thinned corneas can cause the cornea to tilt. Invest. Ophthalmol. Vis. Sci. 2017;58(8):4161.

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      © ARVO (1962-2015); The Authors (2016-present)

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Abstract

Purpose : Retinal detachment repair by scleral buckling can change the original geometry of the eye, and can influence the shape of the cornea as well as the location of the visual axis.. Furthermore, if the cornea is thinned by disease or refractive surgery, corneal shape changes after buckling could be amplified. Rotational deformation of the cornea by buckling has not been well investigated. We evaluated how the application of a segmental scleral buckle changes the orientation of the cornea with respect to the sclera. The three-dimensional finite element analysis model used for this research had previously been utilized to study radial optic neurotomy (RON) surgery (Friberg, T. R., Smolinski, P., Hill, S., & Kurup, S. K. (2008). Biomechanical assessment of radial optic neurotomy. Ophthalmology,115(1),174-180).

Methods : A three-dimensional finite element model of the eye was developed to investigate the effect of a segmental scleral buckle on eye deformation. Linearly elastic mechanical properties of the eye tissues were assumed with the elastic modulus and Poisson’s ratio of the sclera, cornea, retina, zonules and lens taken to be (3 MPa, 0.47), (1.5 MPa, 0.42), (0.02 MPa, 0.49), (360 MPa, 0.4) and (6.88 MPa, 0.49), respectively. An initial intraocular pressure was assumed to be 15 mmHg. The central corneal thickness was taken to be 0.6 mm and a 25% thinning of the cornea by LASIK was considered. The buckle element was assumed to be has 7 mm wide, and extended circumferentially either 110° or 190° around the equator. Buckle heights (indentation) of 0.5, 1 and 1.5 mm were evaluated.

Results : Figure 1 shows a deformed thinned cornea at the plane normal to the plane of the segmental buckle. Figure 2 shows that after placing a superior buckle, the cornea is tilted (rotated) downward at an angle θ. This rotation varies as a function of the segmental buckle extent and indentation, and corneal thinning.

Conclusions : Buckle height has the greatest effect on corneal rotation, but buckle extent has little effect. Except for the 110° buckle with a 1.5 mm height, cornea thickness had only a small effect on cornea tilt.This tilting of the cornea might contribute to post buckling strabismus and misalignment in some patients.

This is an abstract that was submitted for the 2017 ARVO Annual Meeting, held in Baltimore, MD, May 7-11, 2017.

 

Deformed thinned cornea after a 190° scleral buckle.

Deformed thinned cornea after a 190° scleral buckle.

 

Corneal rotation as a function of corneal thickness, buckle height, and buckle extent.

Corneal rotation as a function of corneal thickness, buckle height, and buckle extent.

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