Relationship between corneal biomechanical properties and structural biomarkers in patients with normal-tension glaucoma: a retrospective study

Abstract

BackgroundWe evaluated the relationships between corneal biomechanical properties and structural parameters in patients with newly diagnosed, untreated normal-tension glaucoma (NTG).MethodsAll subjects were evaluated using an Ocular Response Analyzer (ORA) measuring corneal hysteresis (CH) and the corneal resistance factor (CRF). Central corneal thickness (CCT), Goldmann applanation tonometric (GAT) data, axial length, and the spherical equivalent (SE), were also measured. Confocal scanning laser ophthalmoscopy was performed with the aid of a Heidelberg retina tomograph (HRT III). We sought correlations between HRT parameters and different variables including CCT, CH, and the CRF. Multiple linear regression analysis was performed to identify significant associations between corneal biomechanical properties and optic nerve head parameters.ResultsWe enrolled 95 eyes of 95 NTG patients and 93 eyes of 93 normal subjects. CH and the CRF were significantly lower in more advanced glaucomatous eyes (P = 0.001, P = 0.008, respectively). The rim area, rim volume, linear cup-to-disc ratio (LCDR), and mean retinal nerve fiber layer (RNFL) thickness were significantly worse in more advanced glaucomatous eyes (P < 0.001, P < 0.001, P < 0.001, and P = 0.001). CH was directly associated with rim area, rim volume, and mean RNFL thickness (P = 0.012, P = 0.028, and P = 0.043) and inversely associated with LCDR (P = 0.015), after adjusting for age, axial length, CCT, disc area, GAT data, and SE. However, in normal subjects, there were no significant associations between corneal biomechanical properties and HRT parameters.ConclusionsA lower CH is significantly associated with a smaller rim area and volume, a thinner RNFL, and a larger LCDR, independent of disc size, corneal thickness, intraocular pressure, and age.

The Association Between Ocular Rigidity and Neuroretinal Damage in Glaucoma

“…Limited evidence of a relationship between corneal biomechanical parameters and RNFL has been shown in the literature. 49,[52][53][54] Park et al 49 report no significant association between CCT, CH, or CRF with the mean RNFL thickness, although after adjustment, CH and RNFL were directly associated (ß = 0.013, P = 0.043) in NTG patients. In studies measuring RNFL using OCT, no association was found between CH and CRF, and RNFL thickness in suspect or confirmed OAG, as well as in healthy myopic eyes, 52,53 except for one study in which the relationship between CH and RNFL thickness was significant (ß = 0.2, P = 0.001) in OAG.…”

“…1,24,25,[30][31][32][33]45 Various studies have found associations between these parameters and optic nerve parameters, including rim area. 27,31,34,[46][47][48][49][50][51] More specifically, Jonas et al 51 found a significant correlation between CCT and the neuroretinal rim area (r = 0.13, P < 0.001) as measured from stereo optic disc slides in a cohort regrouping normal, OAG, and OHT eyes. Park et al 49 showed that low CCT, CH, and CRF were associated with a smaller rim area (r = 0.256, P = 0.012; r = 0.347, P = 0.001; and r = 0.227, P = 0.027, respectively), as measured using the HRT (Heidelberg Retina Tomograph), in eyes with normotensive glaucoma (NTG) but not in normal eyes.…”

Correlations between corneal biomechanics and specular microscopy in patient with cataract

“…Numerous studies suggest that corneal hysteresis (CH), an indicator of corneal viscoelasticity, is associated with biomechanical properties of the cornea. Some studies showed that CH may be related to the biomechanical characteristics of peripapillary sclera and lamina cribrosa, as they are embryologically developed from the mesoderm and also because the collagen fibers continue with the collagen fibers from the corneal stroma [ 1 - 8 ].…”

Discrepancy Between Normal Tension Glaucoma and Primary Open Angle Glaucoma with Confocal Microscopy Examination of Corneal Nerves

“…Corneal biomechanics and central corneal thickness were analyzed in NTG but few investigations have been made on corneal nerve in NTG. 33,34 . A whorl-like corneal subbasal nerve plexus in normal eyes was depicted by Utsunomiya T's report which was in the inferocentral area of the cornea 27 .…”