The study showed that the longitudinal chromatic aberration in vivo can be easily and reliably estimated with an adapted visual refractometer. The two groups of pseudophakic eyes measured in this study showed different values of chromatic aberration. Its magnitude for SA60AT group was significantly larger than for the control group whereas for SN60WF the difference was not significant. The optical material used for intraocular lens design may have significant influence on the magnitude of the chromatic aberration of the pseudophakic eye, and therefore on its optical and visual performance in polychromatic light.
The curves describing corneal behaviour during air puff tonometry were determined and show that the eye globe rotates towards the nose during measurement. In addition, eye retraction amplitudes may be related to elastic or viscoelastic properties of deeper structures in the eye or behind the eye and this should be further investigated. Many of the proposed new parameters present comparable or even higher repeatability than the standard parameters provided by the Corvis ST.
Purpose: The aim of this research was to present a new approach for the potential characteristics of the anterior eye, based on numerical analysis of the raw data from multiple measurements on 1 eye captured with use of the Ocular Response Analyzer (ORA). Methods: The measurements were carried out 6 times on every eye, one by one, on 29 patients using the ORA. Dependencies between values of 6 applanation pressures P1 and P2 from 1 eye and the new proposed time-dependent parameters sm and smm, obtained from the raw data, were used to determine new characteristic features of the anterior eye. Results: Obtained values for multiple applanation pressures P1 and P2 and their average value Pa from all measurements on 1 eye show strong linear dependencies with the new proposed time-dependent parameter smm. Conclusions: The new parameters based on slope coefficients a1 and a2, their difference Δa, and respective y-intercept values b1, b2, and Δb show some characteristic stability for a multiply measured eye and can be used for its characterization. These parameters can be used for differentiation of the eyes with higher accuracy than those obtained from a single measurement. They are likely related to some biomechanical properties of the anterior eye.
The paper presents, for the first time, corneal buckling, during the air puff applanation, recorded with use of Ocular Response Analyzer (ORA), when the cornea is deeper deformed after its applanation. Precise numerical analysis of the air pressure curve from the raw data, distinct local disturbances of the curve, which appear almost exactly at the time of the first and the second applanations. Thirty measurements taken on six eyes show clear dependencies between times of both applanations and appearances of local wave disturbances on the air pressure curve as well as between the amplitude of pressure wave disturbances and the respective height of applanation curve. These findings can be interpreted as a result of very fast corneal buckling, that produces the air pressure wave, propagating from the cornea towards the device. The quantitative dependencies measured and described in this study, enable to characterize the individual buckling during respective applanations. Due to these individual characterizations and dependencies it is possible to understand and describe better the ultrafast corneal applanation process. Such phenomena could likely be employed to increase the accuracy of measured parameters by ORA or for identifying new types of biomechanical properties of the cornea.
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