Association of Functional Loss With the Biomechanical Response of the Optic Nerve Head to Acute Transient Intraocular Pressure Elevations

Abstract

IMPORTANCE The acute biomechanical response of the optic nerve head (ONH) to intraocular pressure (IOP) elevations may serve as a biomarker for the development and progression of glaucoma. OBJECTIVE To evaluate the association between visual field loss and the biomechanical response of the ONH to acute transient IOP elevations. DESIGN, SETTING, AND PARTICIPANTS In this observational study, 91 Chinese patients (23 with primary open-angle glaucoma [POAG], 45 with primary angle-closure glaucoma, and 23 without glaucoma) were recruited from September 3, 2014, through February 2, 2017. Optical coherence tomography scans of the ONH were acquired at baseline and at 2 sequential IOP elevations (0.64 N and then 0.90 N, by applying forces to the anterior sclera using an ophthalmodynamometer). In each optical coherence tomography volume, lamina cribrosa depth (LCD) and minimum rim width (MRW) were calculated. The mean deviation (MD) and the visual field index (VFI), as assessed by automated perimetry, were correlated with IOP-induced changes of LCD and MRW globally and sectorially. MAIN OUTCOMES AND MEASURES The LCD, MRW, MD, and VFI. RESULTS Among the 91 patients, 39 (42.9%) were women; the mean (SD) age was 65.48 (7.23) years. In POAG eyes, a greater change in LCD (anterior displacement) was associated with worse MD and VFI

Structure-function relationships in glaucoma using enhanced depth imaging optical coherence tomography-derived parameters: a cross-sectional observational study

“…This LC depth pattern across the disease stages could be explained in part by a recent study by Tun et al [42]. Evaluating the correlation between VF indexes values and pressure-induced LC displacement, the authors found that while patients with mild glaucoma presented a posterior LC displacement, those with more advanced disease had an anterior LC displacement [42–44]. These data suggest that much of the LC depth changes in glaucoma patients appear to occur in the early stages of the disease.…”

“…Interestingly, when evaluating ALD values in healthy eyes and eyes with different glaucoma stages, although we found greater ALD values in eyes with mild-to-moderate glaucoma (deeper cups than controls), the same did not occur in eyes with more advanced disease, as mean ALD values seemed to decrease in these eyes. This LC depth pattern across the disease stages could be explained in part by a recent study by Tun et al [42]. Evaluating the correlation between VF indexes values and pressure-induced LC displacement, the authors found that while patients with mild glaucoma presented a posterior LC displacement, those with more advanced disease had an anterior LC displacement [42–44].…”

Optic nerve tissue displacement during mild intraocular pressure elevation: its relationship to central corneal thickness and corneal hysteresis

“…It is of interest that in some of subjects we saw highly localised areas of deformation ( Figure a , upper middle and lower left examples). These results suggest that in addition to the magnitude of displacement, there may be useful information to be gained in differentiating patients that show diffuse compared with more focal deformation in response to IOP elevation . It should be noted that measured deformations could be affected in some way as a result of unknown tracking and registration methods employed by proprietary OCT software, even though software settings for imaging were kept constant.…”

“…reported that greater tissue displacement with IOP elevation was associated with older age and African descent. Some studies have linked these changes to functional deficits; for example, greater transient IOP‐induced thinning of the inferotemporal neuroretinal rim is associated with more severe visual field defect in the corresponding sector . Others have sought to assess the effect of IOP lowering on optic nerve structures in glaucomatous eyes .…”

Optical coherence tomography evaluation of the optic nerve head neuro‐retinal rim in glaucoma

“…In addition to the ‘static’ information about lamina cribrosa morphology and microstructure offered by OCT, another important area of glaucoma research with potential for eventual clinical use is evaluation of dynamic, biomechanical behaviour of the lamina cribrosa, peripapillary sclera and optic nerve head rim tissue. In this scenario, OCT is used to visualise and quantify structural changes of the optic nerve head in response to transient intraocular pressure elevation, which may reveal otherwise hidden susceptibilities to glaucoma . One can imagine that integrating OCT‐A into this kind of approach, perhaps on a swept‐source platform to improve penetration and signal strength, would offer another important dimension.…”