In Vivo 3-Dimensional Strain Mapping of the Optic Nerve Head Following Intraocular Pressure Lowering by Trabeculectomy - Archive ouverte HAL
Journal Articles BMC Ophthalmology Year : 2016

In Vivo 3-Dimensional Strain Mapping of the Optic Nerve Head Following Intraocular Pressure Lowering by Trabeculectomy

Jean-Martial Mari
Michaël Girard
  • Function : Author
Meghna R Beotra
  • Function : Author
Khai Sing Chin
  • Function : Author
Amanjeet Sandhu
  • Function : Author
Monica Clemo
  • Function : Author
Eleni Nikita
  • Function : Author
Deborah S Kamal
  • Function : Author
Nicholas G Strouthidis
  • Function : Author
  • PersonId : 869280
Michaël J.A. Girard
  • Function : Author
Meghna R. Beotra
  • Function : Author
Deborah S. Kamal
  • Function : Author
Nicholas G. Strouthidis
  • Function : Author
  • PersonId : 869280

Abstract

Purpose: To map the 3-dimensional (3D) strain of the optic nerve head (ONH) in vivo after intraocular pressure (IOP) lowering by trabeculectomy (TE) and to establish associations between ONH strain and retinal sensitivity. Design: Observational case series. Participants: Nine patients with primary open-angle glaucoma (POAG) and 3 normal controls. Methods: The ONHs of 9 subjects with POAG (pre-TE IOP: 25.3 +/- 13.9 mmHg; post-TE IOP: 11.8 +/- 8.6 mmHg) were imaged (1 eye per subject) using optical coherence tomography (OCT) (Heidelberg Spectralis, Heidelberg Engineering GmbH, Heidelberg, Germany) before (< 21 days) and after (< 50 days) TE. The imaging protocol was repeated for 3 controls in whom IOP was not altered. In each post-TE OCT volume, 4 tissues were manually segmented (prelamina, choroid, sclera, and lamina cribrosa [LC]). For each ONH, a 3D tracking algorithm was applied to both post-and pre-TE OCT volumes to extract IOP-induced 3D displacements at segmented nodes. Displacements were filtered, smoothed, and processed to extract 3D strain relief (the amount of tissue deformation relieved after TE). Strain relief was compared with measures of retinal sensitivity from visual field testing. Main Outcome Measures: Three-dimensional ONH displacements and strain relief. Results: On average, strain relief (averaged or effective component) in the glaucoma ONHs (8.6%) due to TE was higher than that measured in the normal controls (1.07%). We found no associations between the magnitude of IOP decrease and the LC strain relief (P > 0.05), suggesting biomechanical variability across subjects. The LC displaced posteriorly, anteriorly, or not at all. Furthermore, we found linear associations between retinal sensitivity and LC effective strain relief (P < 0.001; high strain relief associated with low retinal sensitivity). Conclusions: We demonstrate that ONH displacements and strains can be measured in vivo and that TE can relieve ONH strains. Our data suggest a wide variability in ONH biomechanics in the subjects examined in this study. We further demonstrate associations between LC effective strain relief and retinal sensitivity.
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hal-01631235 , version 1 (08-11-2017)

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Jean-Martial Mari, Michaël Girard, Meghna R Beotra, Khai Sing Chin, Amanjeet Sandhu, et al.. In Vivo 3-Dimensional Strain Mapping of the Optic Nerve Head Following Intraocular Pressure Lowering by Trabeculectomy. BMC Ophthalmology, 2016, 123 (6), pp.1190-1200. ⟨10.1016/j.ophtha.2016.02.008⟩. ⟨hal-01631235⟩
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