Date Published: June 27, 2019
Publisher: Public Library of Science
Author(s): Joanna Wasielica-Poslednik, Alexander K. Schuster, Giuseppe Politino, Susanne Marx-Gross, Katharina Bell, Norbert Pfeiffer, Susanne Pitz, Sanjoy Bhattacharya.
To report corneal topometric and aberrometric values in mucopolysaccharidosis (MPS) and to investigate their correlation with biomechanical corneal parameters.
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.
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.
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.
Progressive stromal corneal clouding is the most common ocular pathology in patients suffering from mucopolysaccharidosis (MPS). Irregularities of the corneal surface and an increase in total higher order aberrations (HOAs) were reported in patients suffering from hereditary corneal dystrophies . The results suggested that altered HOAs together with stromal opacity degrade visual function. As corneal clouding appears in MPS and visual acuity can be impaired, we aimed to analyze the shape of the corneal surface and HOAs in MPS patients. To the best of our knowledge this is the first evaluation of these parameters in MPS and this study could help unravel the cause of visual impairment in these patients.
As described in detail previously , this observational clinical study was carried out in accordance with the Declaration of Helsinki. Ethics approval was obtained from the Ethics committee of Rhineland-Palatinate, Germany. All MPS patients were referred from the Department of Lysosomal Storage Disorders of the Children´s Hospital, Mainz University Medical Center. The diagnosis of MPS was confirmed by molecular genetic studies. All patients and volunteers were evaluated between September 2012 and November 2013 at the Department of Ophthalmology University Medical Center of the Johannes Gutenberg University Mainz. Written informed consent was obtained from all participants and/or their parents.
To the best of our knowledge, this is the first study evaluating corneal shape as well as higher order aberrations in mucopolysaccharidosis patients. The wavefront analysis using Pentacam revealed significant asymmetry of the corneal surface as well as altered higher order aberrations in MPS patients in comparison to healthy controls. The quantification of these somehow expected results gives origin for further studies.