A-scan ultrasound in ophthalmology: A simulation tool

Lorena Petrella; Fernando Perdigão; Miguel Caixinha; Mário Santos; Maria Lopes; Marco Gomes; Jaime Santos

doi:10.1016/j.medengphy.2021.09.005

A-scan ultrasound in ophthalmology: A simulation tool

Med Eng Phys. 2021 Nov:97:18-24. doi: 10.1016/j.medengphy.2021.09.005. Epub 2021 Sep 21.

Authors

Lorena Petrella¹, Fernando Perdigão², Miguel Caixinha³, Mário Santos⁴, Maria Lopes⁵, Marco Gomes², Jaime Santos⁴

Affiliations

¹ Department of Electrical and Computer Engineering, Polo II - University of Coimbra, Coimbra 3030-790, Portugal; Centre for Mechanical Engineering, Materials and Processes, University of Coimbra, Coimbra 3030-788, Portugal. Electronic address: lorena.petrella@gmail.com.
² Department of Electrical and Computer Engineering, Polo II - University of Coimbra, Coimbra 3030-790, Portugal; Instituto de Telecomunicações - Polo de Coimbra, Coimbra 3030-790, Portugal.
³ Centre for Mechanical Engineering, Materials and Processes, University of Coimbra, Coimbra 3030-788, Portugal; Department of Physics, University of Beira Interior, Covilhã 6291-001, Portugal.
⁴ Department of Electrical and Computer Engineering, Polo II - University of Coimbra, Coimbra 3030-790, Portugal; Centre for Mechanical Engineering, Materials and Processes, University of Coimbra, Coimbra 3030-788, Portugal.
⁵ Department of Electrical and Computer Engineering, Polo II - University of Coimbra, Coimbra 3030-790, Portugal; Faculty of Science and Technology, Nova University Lisbon, Caparica 2825-149, Portugal.

PMID: 34756334
DOI: 10.1016/j.medengphy.2021.09.005

Abstract

In the present study, we developed a computational tool for simulating the ophthalmological applications of A-scan ultrasound, including cataract characterisation and biometry. A-scan biometry is used to measure the axial length (AL) of the eye before cataract surgery to calculate the refractive power of the intraocular lens to be implanted. Errors in the measurement of the AL lead to post-surgical refractive errors. The simulation tool was developed using the k-Wave Matlab toolbox, together with a user-friendly interface developed in Matlab. Diverse error sources were evaluated. Constant ultrasound speed assumptions may introduce refractive errors of up to 0.6 D; by contrast, probe positioning errors had a lower impact, of up to 0.11 D. The correct identification of the Bruch's membrane is limited not only by axial resolution constraints but also by the low reflection coefficient at the retina/choroid interface. Regarding cataract characterisation, the amplitudes of the echoes reflected at the lens interfaces are sensitive to diverse cataract types and severities, and a more realistic representation could be obtained by using a higher resolution in the eye grid; however, the required computational times would make simulations impracticable when using personal computers. The simulation tool shows good versatility for evaluating diverse aspects of A-scan biometry.

Keywords: A-scan ultrasound; Biometry; Cataract; Eye axial length; Intraocular lenses; Simulation.

Publication types

Research Support, Non-U.S. Gov't

MeSH terms

Biometry
Cataract Extraction*
Lenses, Intraocular*
Ophthalmology*
Refraction, Ocular