June 2017
Volume 58, Issue 8
Open Access
ARVO Annual Meeting Abstract  |   June 2017
The effect of segmental scleral buckling on the power and symmetry of the cornea, corneal thickness, the axial length, and the total power of the eye: A biomechanical model.
Author Affiliations & Notes
  • Raed Aldhafeeri
    Mechanical Engineering, University of Pittsburgh, Pittsburgh, Pennsylvania, United States
    Mechanical Engineering, University of Hafr Al Batin, Hafr Al Batin, Saudi Arabia
  • Patrick Smolinski
    Mechanical Engineering, University of Pittsburgh, Pittsburgh, Pennsylvania, United States
  • Thomas R Friberg
    Department of Ophthalmology and Bioengineering, University of Pittsburgh, Pittsburgh, Pennsylvania, United States
  • Footnotes
    Commercial Relationships   Raed Aldhafeeri, None; Patrick Smolinski, None; Thomas Friberg, None
  • Footnotes
    Support  None
Investigative Ophthalmology & Visual Science June 2017, Vol.58, 4171. doi:
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      Raed Aldhafeeri, Patrick Smolinski, Thomas R Friberg; The effect of segmental scleral buckling on the power and symmetry of the cornea, corneal thickness, the axial length, and the total power of the eye: A biomechanical model.. Invest. Ophthalmol. Vis. Sci. 2017;58(8):4171.

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

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Abstract

Purpose : Lasik procedures and corneal disease often result in corneal thinning. Scleral buckles for retinal detachment repair induce myopia by increasing the axial length, yet the effect of a buckle on an eye with a thinned cornea is largely unknown. This study was done to evaluate how the application of a segmental scleral buckle affects the deformation of the eye including the axial length and the total eye power. The three-dimensional finite element analysis model used for this research had previously been used to simulate the effect of radial optic neurotomy (RON) surgery on venous occlusions (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 deformation caused by the application of a segmental scleral buckle on an eye (Figure 1). A physiological pressure of 2 kPa was assumed. The mechanical properties of the different tissues were assumed to be linearly elastic with the elastic modulus and Poisson’s ratio of the sclera, cornea, retina, zonules and lens being (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. The original central corneal thickness was fixed at 0.6 mm and was reduced by 25% by Lasik. The buckle width was taken to be 7 mm and extended 110° or 190° around the circumference of the eye. Buckle heights (indentation) of 0.5, 1 and 1.5 mm were assessed.

Results : Figure 2 shows the total change in the eye power at the 90° meridian as a function of segmental buckle extent, indentation, and cornea thinning. Note the calculated total change of power arises from both an axial length change and alteration of cornea power. The majority of difference between the standard and thinned cornea is due to a change in cornea power.

Conclusions : Increased buckle extent and buckle height in an eye with a thinned cornea leads to steepening of the cornea and an increased axial length. These effects both lead to an increase in myopia. Patients who have undergone successful lasik procedures to avoid the need for glasses or contact lenses are susceptible to this myopic shift after scleral buckling.

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

 

Figure 1.Deformed model of an eye with 190°buckle.

Figure 1.Deformed model of an eye with 190°buckle.

 

Figure 2.Total change of the eye power at 90°of the cornea.

Figure 2.Total change of the eye power at 90°of the cornea.

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