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Diurnal variations in new biomechanical corneal and ocular parameters measured with CorVis ST

Poster Details

First Author: J.Gonzalez-Meijome PORTUGAL

Co Author(s):    S. Peixoto-de-Matos   L. Rico-del-Viejo   H. Ferreira-Neves   L. Dias   J. Salgado-Borges  

Abstract Details


To evaluate the changes in intra-ocular pressure (IOP) and new biomechanical parameteres of the cornea measured with Corvis ST in a population of young healthy patients in the morning and in the afternoon.


CEORLab - Center of Physics - University of Minho - Braga - Portugal


Fifty-three eyes from 53 young and healthy patients (47 females, 6 males) were evaluated with Corvis ST (Oculus, Wetzlar, Germany). Measurements were performed in the morning between 9:00 and 11:00 AM (minimum of 2 hours after awaking) and repeated in the afternoon between 16:00 and 18:00 after 7 to 9 hours. IOP, central corneal thickness (CCT), and 28 other parameters potentially related with the biomechanical corneal and ocular response to a controlled air puff were obtained from Corvis ST. Considering the normal distribution of data, comparisons were performed using paired sample T-test.


The intra-ocular pressure decreased from the morning to the afternoon (p=0.035). Most of the remaining parameters extracted from the Corvis ST remained constant over the course of the day. Parameters related with applanation 1 were significantly decreased form the morning to the afternoon visit, including Applanation 1 Time (p=0.033), Applanation 1 Deflection Length (p=0.044) and Application 1 Peak (p=0.049). Otherwise the changes observed were unremarkable and non-statistically significant.


Present results suggest that the biomechanical parameters (habitual and new ones) extracted from the Corvis ST instrument are consistent over the course of the day. However, parameters related with first applanation decrease significantly from the morning to the afternoon. If these changes are the cause or the consequence of the observed lowering IOP needs to be further investigated. The role of circadian changes in the corneal biomechanical properties of the eye might also play a role on circadian changes in IOP values. FINANCIAL INTEREST: NONE

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