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In vivo assessment of changes in corneal hysteresis and lamina cribrosa position during acute intraocular pressure elevation in eyes with markedly asymmetrical glaucoma

Authors Gizzi C, Cellini M, Campos EC

Received 13 September 2017

Accepted for publication 30 January 2018

Published 15 March 2018 Volume 2018:12 Pages 481—492

DOI https://doi.org/10.2147/OPTH.S151532

Checked for plagiarism Yes

Review by Single-blind

Peer reviewers approved by Dr Amy Norman

Peer reviewer comments 3

Editor who approved publication: Dr Scott Fraser


Corrado Gizzi, Mauro Cellini, Emilio C Campos

Department of Experimental, Diagnostic and Speciality Medicine, Ophthalmology Service, University of Bologna, Bologna, Italy

Purpose: To investigate the biomechanical response of the cornea, lamina cribrosa (LC), and prelaminar tissue (PT) to an acute intraocular pressure (IOP) increase in patients with markedly asymmetrical glaucoma and in healthy controls.
Patients and methods: A total of 24 eyes of 12 patients with markedly asymmetrical primary open-angle glaucoma (POAG) and 12 eyes of 12 healthy patients were examined with spectral-domain optical coherence tomography (SD-OCT) and ocular response analyzer (ORA) at baseline and during acute IOP elevation by means of an ophthalmodynamometer. The displacement of the LC and PT and the change in corneal hysteresis (CH) and corneal resistance factor (CRF) were evaluated.
Results: Following a mean IOP increase of 12.3±2.4 mmHg, eyes with severe glaucoma demonstrated an overall mean anterior displacement of the LC (-6.58±26.09 µm) as opposed to the posterior laminar displacement in eyes with mild glaucoma (29.08±19.28 µm) and in healthy eyes (30.3±10.9; p≤0.001 and p=0.001, respectively). The PT displaced posteriorly during IOP elevation in all eyes. The CH decreased in eyes with severe glaucoma during IOP elevation (from 9.30±3.65 to 6.92±3.04 mmHg; p=0.012), whereas the CRF increased markedly in eyes with mild glaucoma (from 8.61±2.30 to 12.38±3.64; p=0.002) and in eyes with severe glaucoma (from 9.02±1.48 to 15.20±2.06; p=0.002). The increase in CRF correlated with the anterior displacement of the LC in eyes with severe glaucoma.
Conclusion: Eyes with severe glaucoma exhibited a mean overall anterior displacement of the anterior laminar surface, while eyes with mild glaucoma and healthy eyes showed a posterior displacement of the LC during IOP elevation. The CH decreased significantly from baseline only in eyes with severe glaucoma, but the CRF increased significantly in all glaucomatous eyes. The CRF increase correlated with the anterior displacement of the LC in eyes with severe glaucoma.

Keywords: glaucoma, lamina cribrosa, cornea, hysteresis, ophthalmodynamometer, biomechanics, asymmetry
 

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