Factors associated with topographic changes of the optic nerve head induced by acute intraocular pressure reduction in glaucoma patients

Abstract

Purpose To investigate factors associated with changes in optic nerve head (ONH) topography after acute intraocular pressure (IOP) reduction in patients with primary open-angle glaucoma (POAG). Methods Untreated POAG patients (IOP 421 mm Hg) were prospectively enrolled. Systemic and ocular information were collected, including central corneal thickness (CCT) and corneal hysteresis (CH). All patients underwent confocal scanning laser ophthalmoscopy and tonometry (Goldmann) before and 1 h after pharmacological IOP reduction. The mean of three measurements was considered for analysis. Changes in each ONH topographic parameter were assessed (one eye was randomly selected), and those that changed significantly were correlated with patient's systemic and ocular characteristics. Results A total of 42 patients were included (mean age, 66.7 ± 11.8 years). After a mean IOP reduction of 47.3±11.9%, significant changes were observed in cup area and volume, and in rim area and volume (Po0.01), but not in mean cup depth (P ¼ 0.80). Multiple regression analysis (controlling for baseline IOP and magnitude of IOP reduction) showed that CH (r 2 ¼ 0.17, Po0.01) and diabetes diagnosis (r 2 X0.21, Po0.01) were negatively correlated with the magnitude of changes in ONH parameters, whereas the cup-to-disc ratio was positively correlated (r 2 ¼ 0.30, Po0.01). Age, race, disc area, and CCT were not significant (PX0.12). Including all significant factors in a multivariable model, only the presence of diabetes remained significantly associated with all ONH parameters evaluated (Po0.01). Conclusions Different systemic and ocular factors, such as diabetes, CH, and the relative size of the cup, seem to be associated with the magnitude of changes in ONH topography after acute IOP reduction in POAG patients. These associations partially explain the ONH changes observed in these patients and suggest that other factors are possibly implicated in an individual susceptibility to IOP.

Lack of Association Between Corneal Hysteresis and Corneal Resistance Factor With Glaucoma Severity in Primary Angle Closure Glaucoma

“…They suggested that the reduced viscous damping of the cornea, as represented by a low CH, reflects an increased likelihood of deformability of the ONH complex. 19 The present study on PACG eyes found no association between disease severity and either CH or CRF. Our study comprised exclusively of subjects with established glaucoma unlike the previous published studies that have included a wider range of subjects encompassing glaucoma suspects and established glaucoma.…”

“…Although Vu et al 18 showed similar weak associations (r ¼ À0.11 to À0.15) of VCDR with CH, they did not report on the association with CRF. Likewise, Prata et al 19 demonstrated significant correlations with mean cup depth (r ¼ À0.34) and linear cup-disc ratio (r ¼ À0.41) in their evaluation of 42 newly diagnosed POAG patients. They suggested that the reduced viscous damping of the cornea, as represented by a low CH, reflects an increased likelihood of deformability of the ONH complex.…”

Topographic Optic Disc Changes After Successful Trabeculectomy Evaluated Using Spectral Domain Optical Coherence Tomography

“…21,22 Furthermore, anterior displacement of prelaminar tissue following trabeculectomy for OAG has been described in a number of studies with variable results. Patients in these studies were followed up for periods varying from several weeks to 2 years, [1][2][3][4][5] and different patient populations and imaging platforms were used. Results from our study confirm topographic changes in adult ONHs following trabeculectomy, with significant anterior displacement of prelaminar tissue 1 week and 1 month after surgery.…”

“…A partial reversal of optic disc cupping and an improvement in neuroretinal rim appearance is observed in children after trabeculectomy, but is less commonly seen in adults. [1][2][3][4][5] Biomechanical factors that affect the optic nerve head (ONH) may strongly influence the glaucomatous process because the posterior sclera and lamina cribrosa (LC) are implicated in the pathophysiology of glaucomatous optic neuropathy. 6,7 Stereoscopic optic disc photography and scanning laser tomography have been widely used to study optic disc cupping reversal in adults after IOP reduction.…”

Reevaluating the Effectiveness of Corneal Collagen Cross-linking and Its True Biomechanical Effect in Human Eyes

“…5 Keratoconus, Fuchs' dystrophy, Glaucoma, Marfan syndrome, and post-LASIK patients have been found to have low CH and CRF. [6][7][8][9][10][11][12][13] The corneal visualization Scheimpflug technology tonometer (Corvis ST tonometry: CST; Oculus, Wetzlar, Germany) was introduced more recently and allows quantitative and visual assessment of the biomechanical properties of the cornea. 14 The Corvis ST is a noncontact tonometer with an integrated ultra-high-speed Scheimpflug camera, enabling the direct visualization of corneal movement during the application of a rapid air-puff.…”