Sensory and Motor Visual Functions in Parkinson’s Disease with Respect to Freezing of Gait Symptoms

Abstract

Purpose: Investigating intraobserver and interobservers repeatability, reproducibility and limits of agreement of anterior corneal indices using three different topographers. Methods: Forty five participants were recruited, involved two examiners and two sessions. They were assessed in random order with EyeSys Vista, Medmont E-300 and manual keratometer. The corneal indices were horizontal keratometer, vertical keratometer, eccentricity and inferior superior index. Repeatability and reproducibility of corneal power measurements were assessed based on the intersession, intrasession, Intraclass Correlation Coefficient (ICC), Spearman’s correlations and agreement was evaluated by Bland Altman test (95% Limits Of Agreement, LoA). Result: All devices showed high repeatability (p < 0.01) and reproducibility (ICC>0.75) of the corneal indices. Multivariate analysis of variance showed nonsignificant findings between visits and examiners (p > 0.05), while there was a significant difference between the devices among keratometric readings (p < 0.0001). The differences between the EyeSys, Medmont and manual keratometer were significant (p < 0.01). Moderate relationship was found between the keratometric readings with the three devices (r = 0.60, p < 0.0001). The 95% LoA for EyeSys and Medmont of the keratometric readings were larger than those for the Medmont and manual keratometer (±0.3 mm). The eccentricity and inferior superior index measurements were not significantly different between the EyeSys and Medmont (p > 0.01). Conclusion: All devices exhibited excellent repeatability and reproducibility. The EyeSys is portable, repeatable, and reliable and have stable interobservers variability. Although EyeSys would not be used interchangeably with the other two devices due to lower agreement, corrected linear calculation was suggested to manage the differences between the EyeSys and the two devices.