Influence of Corneal Opacity on Intraocular Pressure Assessment in Patients with Lysosomal Storage Diseases

Abstract

AimsTo 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.Methods25 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.ResultsThere 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).ConclusionsORA 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.Trial RegistrationClinicalTrials.gov NCT01695161

Corneal topometric, aberrometric and biomechanical parameters in mucopolysaccharidosis patients

“…As described in detail previously [11], 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.…”

“…The patients evaluated in this study are part of the cohort from our previous trial [11]. As in subjects with the most advanced corneal opacity of grade 4 Scheimpflug imaging of the posterior corneal surface is difficult, we excluded these patients from this substudy.…”

“…So far, limited information is available concerning the shape of MPS—affected corneas. Although the central corneal thickness (CCT) in MPS varies strongly, its average thickness seems to be comparable to healthy controls [10,11]. Corneal density is increased when compared to healthy controls and strongly correlates with the grade of corneal clouding [11,12].…”

“…Although the central corneal thickness (CCT) in MPS varies strongly, its average thickness seems to be comparable to healthy controls [10,11]. Corneal density is increased when compared to healthy controls and strongly correlates with the grade of corneal clouding [11,12]. In a previous study, we analyzed biomechanical indices of corneas affected with lysosomal storage diseases and their influence on intraocular pressure measurements [11].…”

“…Corneal density is increased when compared to healthy controls and strongly correlates with the grade of corneal clouding [11,12]. In a previous study, we analyzed biomechanical indices of corneas affected with lysosomal storage diseases and their influence on intraocular pressure measurements [11]. Corneal hysteresis (CH) and corneal resistance factor (CRF) assessed with Ocular Response Analyzer (ORA, Reichert Inc., Buffalo, NY) strongly correlated with the grade of corneal opacity.…”