Comparison of rebound tonometry, Perkins applanation tonometry and ocular response analyser in mucopolysaccharidosis patients

Aims To investigate the feasibility and to compare three devices measuring intraocular pressure (IOP) in mucopolysaccharidosis patients (MPS): iCare rebound tonometer (RT), Perkins applanation tonometer (PAT) and ocular response analyzer (ORA) Methods MPS patients who underwent at least two examinations out of: RT, PAT and ORA at the same visit were identified and retrospectively analyzed in this study. Results 17 patients fulfilled the inclusion criterion. In all 17 patients IOP measurements were performed with RT (34 eyes) and ORA (33 eyes), while PAT measurement was possible in only 12 (24 eyes) patients. The RT, corneal-compensated intraocular pressure (IOPcc) and Goldmann-correlated intraocular pressure (IOPg) differed relevantly from IOP assessed with PAT. Corneal clouding in MPS patients correlated positively with PAT, RT and IOPg (r = 0.3, 0.5, and 0.5 respectively), but not with IOPcc (r = 0.07). The MPS-related corneal clouding correlated positively with biomechanical corneal parameters assessed with ORA: corneal hysteresis (r = 0.77) and corneal resistance factor (r = 0.77) either. Conclusions RT and ORA measurements were tolerated better than applanation tonometry in MPS patients. IOP measurements assessed with RT and ORA differed relevantly from PAT. Corneal-compensated IOP assessed with ORA seems to be less affected by the MPS-related corneal clouding than applanation or rebound tonometry. RT and ORA measurements should be preferred for IOP assessment in patients with MPS

Intraclass correlation coefficients (ICCs), 95% confidence intervals and p-values for agreement between: rebound tonometry (RT-IOP), Goldmann-correlated intraocular pressure (ORA-IOPg), corneal-compensated intraocular pressure (ORA-IOPcc) and Perkins applanation tonometry (PAT-IOP) in right (OD) and left (OS) eyes.

<p>Intraclass correlation coefficients (ICCs), 95% confidence intervals and p-values for agreement between: rebound tonometry (RT-IOP), Goldmann-correlated intraocular pressure (ORA-IOPg), corneal-compensated intraocular pressure (ORA-IOPcc) and Perkins applanation tonometry (PAT-IOP) in right (OD) and left (OS) eyes.</p

Clinical details regarding study patients.

<p>*Left eye of the patient no. 3 was excluded from the statistical analysis due to corneal transplantation.</p><p>Grading of corneal clouding according to Couprie et al. [<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0133586#pone.0133586.ref012" target="_blank">12</a>]; BCVA–best corrected visual acuity (decimal); OD–right eye; OS–left eye.</p

Regression graphs presenting Spearman´s correlation coefficient between Goldmann-correlated intraocular pressure (IOPg) and corneal clouding.

<p>Regression graphs presenting Spearman´s correlation coefficient between Goldmann-correlated intraocular pressure (IOPg) and corneal clouding.</p

Median, 25% percentile, 75% percentile and ranges of rebound tonometry (RT-IOP), Perkins applanation tonometry (PAT-IOP), corneal-compensated intraocular pressure (IOPcc), Goldmann-correlated intraocular pressure (IOPg), corneal hysteresis (CH) and corneal resistance factor (CRF) for the right (OD) and left eyes (OS).

<p>All IOP values are presented in mmHg.</p><p>Median, 25% percentile, 75% percentile and ranges of rebound tonometry (RT-IOP), Perkins applanation tonometry (PAT-IOP), corneal-compensated intraocular pressure (IOPcc), Goldmann-correlated intraocular pressure (IOPg), corneal hysteresis (CH) and corneal resistance factor (CRF) for the right (OD) and left eyes (OS).</p

Regression graphs presenting Spearman´s correlation coefficient between Perkins applanation tonometer (PAT) and corneal clouding.

<p>Regression graphs presenting Spearman´s correlation coefficient between Perkins applanation tonometer (PAT) and corneal clouding.</p

Bland-Altman plots show the agreement between rebound tonometry (RT-IOP), Goldmann-correlated intraocular pressure (ORA-IOPg), corneal-compensated intraocular pressure (ORA-IOPcc) and Perkins applanation tonometry (PAT-IOP) in right eyes.

<p>Bland-Altman plots show the agreement between rebound tonometry (RT-IOP), Goldmann-correlated intraocular pressure (ORA-IOPg), corneal-compensated intraocular pressure (ORA-IOPcc) and Perkins applanation tonometry (PAT-IOP) in right eyes.</p

Regression graphs presenting Spearman´s correlation coefficient between corneal-compensated intraocular pressure (IOPcc) and corneal clouding.

<p>Regression graphs presenting Spearman´s correlation coefficient between corneal-compensated intraocular pressure (IOPcc) and corneal clouding.</p