Corneal topometric, aberrometric and biomechanical parameters in mucopolysaccharidosis patients

Abstract

Aims To report corneal topometric and aberrometric values in mucopolysaccharidosis (MPS) and to investigate their correlation with biomechanical corneal parameters. Methods One randomly chosen eye of 20 MPS patients with no to moderate corneal clouding and one eye of 23 healthy controls with comparable age were prospectively included into this study. Corneal surface regularity was assessed by index of surface variance (ISV), -vertical asymmetry (IVA), -height asymmetry (IHA), -height decentration (IHD); keratoconus index (KI), central keratoconus index (CKI) and Zernike indices of anterior and posterior corneal surface using Scheimpflug imaging (Pentacam). Corneal resistance factor (CRF) and corneal hysteresis (CH) were assessed by Ocular Response Analyzer. Statistical analyses were performed using Mann-Whitney-Test and Spearman Correlation Coefficients. Results IVA, ISV, IHD, IHA, but not KI and CKI were significantly higher in MPS patients compared to age matched healthy controls. Spherical aberration and asphericity coefficients either at the anterior or at the posterior corneal surface differed significantly between both groups. The grade of the MPS-associated corneal opacity correlated significantly with ISV (rho = 0.52), IVA (rho = 0.54), IHA (rho = 0.57) and IHD (rho = 0.48). Density of the MPS-affected corneas correlated significantly with ISV (rho = 0.52), IVA (rho = 0.72), IHA (rho = 0.57), IHD (rho = 0.69), 3rd order horizontal trefoil aberration at the posterior (rho = 0.62) and anterior surface (rho = 0.48) as well as with CH (rho = 0.55) and CRF (rho = 0.57). Spherical aberration at the back surface correlated with CRF and CH in MPS and in healthy controls. Conclusions This is the first study analyzing shape of the corneal surface in MPS patients. Topometric indices of corneal asymmetry are significantly increased and correlate with MPS-related corneal opacity and density. Spherical aberration and asphericity coefficient at the front and at the back corneal surface differ significantly between MPS and healthy controls.

Mucopolysaccharidosis: A broad review

“…Various topographic indices such as index of vertical asymmetry, index of height asymmetry, and index of height decentration have been found to increase in patients with MPS. [ 12 ] The density and grade of corneal opacity is said to correlate well with the topometric indices of corneal asymmetry. [ 12 ]…”

“…[ 12 ] The density and grade of corneal opacity is said to correlate well with the topometric indices of corneal asymmetry. [ 12 ]…”

“…Alterations in HOAs to corneal opacification causes degradation of visual functions in terms of reduced levels of contrast sensitivity and occurrence of symptoms such as monocular diplopia, halos, starburst, and glare experienced by patients with MPS. [ 12 ] Corneal hysteresis (CH) and corneal resistance factor (CRF) values also correlate with increased corneal thickness values due to GAG deposition. Ocular response analyzer values have been reported to better predict intraocular pressure (IOP) readings in these patients.…”