title: Influence of Corneal Opacity on Intraocular Pressure Assessment in Patients with Lysosomal Storage Diseases.
abstract: OBJECTIVE
  To investigate an influence of mucopolysaccharidosis (MPS)- and Morbus Fabry-associated corneal opacities on intraocular pressure (IOP) measurements and to evaluate the concordance of the different tonometry methods.
  
  
  METHODS
  25 MPS patients with or without corneal clouding, 25 Fabry patients with cornea verticillata ≥ grade 2 and 25 healthy age matched controls were prospectively included into this study. Outcome measures: Goldmann applanation tonometry (GAT); palpatory assessment of IOP; Goldmann-correlated intraocular pressure (IOPg), corneal-compensated intraocular pressure (IOPcc), corneal resistance factor (CRF) and corneal hysteresis (CH) assessed by Ocular Response Analyzer (ORA); central corneal thickness (CCT) and density assessed with Pentacam. Statistical analysis was performed using linear mixed effect models and Spearman correlation coefficients. The concordance between tonometry methods was assessed using Bland-Altman analysis.
  
  
  RESULTS
  There was no relevant difference between study groups regarding median GAT, IOPg, IOPcc and CCT measurements. The limits of agreement between GAT and IOPcc/IOPg/palpatory IOP in MPS were: [-11.7 to 12.1mmHg], [-8.6 to 15.5 mmHg] and [- 5.4 to 10.1 mmHg] respectively. Limits of agreement were less wide in healthy subjects and Fabry patients. Palpatory IOP was higher in MPS than in healthy controls and Fabry patients. Corneal opacity correlated more strongly with GAT, IOPg, CH, CRF, CCT and corneal density in MPS (r = 0.4, 0.5, 0.5, 0.7, 0.6, 0.6 respectively) than in Fabry patients (r = 0.3, 0.2, -0.03, 0.1, 0.3, -0.2 respectively). In contrast, IOPcc revealed less correlation with corneal opacity than GAT in MPS (r = 0.2 vs. 0.4).
  
  
  CONCLUSIONS
  ORA and GAT render less comparable IOP-values in patients suffering from MPS-associated corneal opacity in comparison to Fabry and healthy controls. The IOP seems to be overestimated in opaque MPS-affected corneas. GAT, IOPg and biomechanical parameters of the cornea correlate more strongly with the corneal clouding than IOPcc in MPS patients.
  
  
  BACKGROUND
  ClinicalTrials.gov NCT01695161.
authors.affiliation: Department of Ophthalmology, University Medical Center, Johannes Gutenberg- University Mainz, Germany.
authors.forename: Joanna
authors.identifier: http://orcid.org/0000-0002-7025-8280
authors.initials: J
authors.lastname: Wasielica-Poslednik
authors.affiliation: Department of Ophthalmology, University Medical Center, Johannes Gutenberg- University Mainz, Germany.
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Politino
authors.affiliation: Institute for Medical Biostatistics, Epidemiology and Informatics (IMBEI), University Medical Center, Johannes Gutenberg University Mainz, Germany.
authors.forename: Irene
authors.initials: I
authors.lastname: Schmidtmann
authors.affiliation: Department of Ophthalmology, University Medical Center, Johannes Gutenberg- University Mainz, Germany.
authors.forename: Katrin
authors.initials: K
authors.lastname: Lorenz
authors.affiliation: Department of Ophthalmology, University Medical Center, Johannes Gutenberg- University Mainz, Germany.
authors.forename: Katharina
authors.initials: K
authors.lastname: Bell
authors.affiliation: Department of Ophthalmology, University Medical Center, Johannes Gutenberg- University Mainz, Germany.
authors.forename: Norbert
authors.initials: N
authors.lastname: Pfeiffer
authors.affiliation: Department of Ophthalmology, University Medical Center, Johannes Gutenberg- University Mainz, Germany.
authors.forename: Susanne
authors.initials: S
authors.lastname: Pitz
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D003315:Cornea / Q000473:pathology / Q000503:physiopathology; D003318:Corneal Opacity / Q000209:etiology / Q000473:pathology / Q000503:physiopathology; D005260:Female; D006801:Humans; D007429:Intraocular Pressure; D008297:Male; D008875:Middle Aged; D009083:Mucopolysaccharidoses / Q000150:complications / Q000473:pathology / Q000503:physiopathology