Correlation between elastic energy stored in an eye and visual field progression in glaucoma

Abstract

PurposeTo investigate whether the elastic energy stored in an eyeball at highest concavity (highest concavity energy; HCE), calculated with Corivs ST (CST, OCULUS), correlates with glaucomatous visual field (VF) progression.Methods108 eyes from 70 primary open angle-glaucoma patients were studied. The HCE was calculated using CST parameters. For each eye, the mean total deviation (mTD) of the 52 test points in the 24–2 Humphrey Field Analyzer test pattern was calculated and the mTD progression rate was determined from eight reliable VFs. Eyes were subdivided into: subgroups with low- or high-whole eye motion maximal length (WEM-d) and subgroups with short- or long-time taken to reach WEM-d (WEM-t), as measured with CST. The associations between mTD progression rate and HCE and other ocular/systemic parameters including age, Goldmann applanation tonometry based-intraocular pressure [GAT-IOP], and corneal hysteresis [CH] from the Ocular Response Analyzer (ORA®, Reichert) were investigated using the linear mixed model. The optimal model to describe mTD progression rate was selected from all possible combinations according to the second order bias corrected Akaike Information Criterion index.ResultsOptimal models to describe mTD progression rate included: CH in the model for all eyes, age and HCE in the model for the WEM-d low group, HCE in the model for the WEM-t short group, mean GAT-IOP in the model for the WEM-d high group, and age in the model for the WEM-t long-group.ConclusionsHCE was associated with glaucomatous VF progression in eyes with minimal whole eye motion (low WEM-d and WEM-t subgroups).

Comparison of two analyzer measurements focusing on material stiffness among normal, treatment-naïve, and treated glaucoma eyes

“…The usefulness of CH in (early) treatment-naïve normal-tension glaucoma needs to be revisited in the future with a larger dataset with different disease severities. On the other hand, in our previous reports, the progression of glaucoma was faster with lower CH in mostly normal tension glaucoma eyes 16 , 39 , 40 . This may, together with the present finding that CH in treatment-naïve POAG eyes was comparable to that in normal eyes, imply that CH is not involved in the pathogenesis of normal tension glaucoma itself, but may reflect the change associated with the therapeutic interventions.…”

Biomechanical Glaucoma Factor and Corneal Hysteresis in Treated Primary Open-Angle Glaucoma and Their Associations With Visual Field Progression

“…Previous studies suggest that CH reflects the damping capacity of the cornea 5,17,27 ; the eyes with higher CH may have an ONH structure that protects the optic nerve axons from external stress such as IOP, thus preventing glaucoma progression. [28][29][30][31][32] Furthermore, the correlation between CH and VF progression may be accounted for by the correlation between CH and (measured) IOP; that is, CH is correlated with a real IOP and also affects IOP measurement. 33 The absence of IOP in the optimal linear mixed model does not indicate IOP is not associated with the progression of VF, because the effect of IOP may be masked by the inclusion of CH in the optimal model.…”

Efficacy of corneal shape index in the evaluation of ocular hypertension, primary open-angle glaucoma and exfoliative glaucoma

“…3,6 The biomechanical properties of the cornea seems related to those of the LC or peripapillary sclera, being a continuous collagen sheaths with similar extracellular matrix constituents, which can influence the response of the ONH to IOP and the degree of axonal nerve damage. 7 Alterations in the corneal biomechanics can be a marker of the glaucomatous damage, 7,8 since it is influenced by the structural properties of the LC and peripapillary sclera. The corneal thickness is an important risk factor for glaucoma.…”