Elastotonometry for evaluation of biomechanical characteristics of the eye after surgical hyperopia correction

S.M. Bauer

Saint-Petersburg State University

L.A. Venatovskaya

Saint-Petersburg State University

L.A. Avershina

Cheboksary branch of S.N. Fyodorov National Medical Research Center «MNTK «Eye Microsurgery»

S.M. Pikusova

Postgraduate Doctors’ Training Institute

Elastotonometry for evaluation of biomechanical characteristics of the eye after surgical hyperopia correction

Authors:

S.M. Bauer, L.A. Venatovskaya, L.A. Avershina, S.M. Pikusova

More about the authors

Journal: Russian Annals of Ophthalmology. 2020;136(5): 32‑38

DOI: 10.17116/oftalma202013605132

Downloaded: 43

To cite this article:

Bauer SM, Venatovskaya LA, Avershina LA, Pikusova SM. Elastotonometry for evaluation of biomechanical characteristics of the eye after surgical hyperopia correction. Russian Annals of Ophthalmology. 2020;136(5):32‑38. (In Russ., In Engl.)
https://doi.org/10.17116/oftalma202013605132

Доказательная гастроэнтерология: pro et contra

Актуальные вопросы педиатрической практики

Использование инфографики авторами научных работ

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PURPOSE

To build a mathematical model that would use elastotonometry to assess biomechanical properties of the eye in treatment of hyperopia with LASIK and FemtoLASIK surgeries.

MATERIAL AND METHODS

The study included 64 operations: 34 FemtoLASIK surgeries, and 31 LASIK surgeries. All patients before and after surgery underwent standard examination necessary for keratorefractive surgery, including elastotonometry. The next step was the analysis of elastotonometry curves and eye finite element model in the software package Ansys (Ansys, Inc.; U.S.A.). During the analysis, the fibrous membrane was modeled by two spherical segments, which before elastotonometry were influenced only by true intraocular pressure (IOP). There was a problem of determining tonometric IOP when the cornea is pressured with flat bottomed loads during elastotonometry. It was taken into account that at the first stage of loading, the IOP was applied, and then the force corresponding to the weight of the tonometer. After tonometry, IOP increased so that the volume inside the composite membrane corresponded to the value before loading.

RESULTS

Mathematical modeling has shown that after surgical treatment of hyperopia, flexural stiffness of the cornea decreases, elevation of the elastotonometry curve increases, and the higher the true IOP, the greater the elevation. The greatest increase in lift due to increased IOP is observed after LASIK operation, while after FemtoLASIK this change is not significant, in which case the dependence of tonometric IOP on the weight of the load is almost linear.

CONCLUSION

The obtained results allow for elastotonometry to be recommend for further medical research as a promising method for assessing biomechanical characteristics of the fibrous membrane of the eye.

Keywords:

elastotonometry

hyperopia

conjugate membranes

Maklakov tonometer

LASIK

FemtoLASIK

Authors:

S.M. Bauer

Saint-Petersburg State University

L.A. Venatovskaya

Saint-Petersburg State University

L.A. Avershina

Cheboksary branch of S.N. Fyodorov National Medical Research Center «MNTK «Eye Microsurgery»

S.M. Pikusova

Postgraduate Doctors’ Training Institute

Received:

28.11.2019

Accepted:

16.06.2020

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