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Corneal deformation parameters and IOP measurements of post corneal transplant eyes by a Scheimpflug-based tono-pachymeter

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Session Details

Session Title: Presented Poster Session: Corneal Biomechanics

Session Date/Time: Sunday 06/09/2015 | 09:30-11:00

Paper Time: 10:50

Venue: Poster Village: Pod 4

First Author: : P.Mandal UK

Co Author(s): :    W. Wan Abdul Halim   M. Rana   M. Nessim   S. Naroo   S. Shah  

Abstract Details


This study aims to evaluate the differences in intraocular pressure (IOP) and corneal biomechanical parameters of normal eyes and eyes that have undergone corneal surgery.


This prospective comparative study involved a total of 142 eyes of 122 patients. The study was done at Birmingham and Midland Eye Centre, Birmingham, United Kingdom.


The patients were divided as control (n=70), post-PK (n=19), post-DSAEK (n=26) and post-DALK (n=27). Each participant underwent assessment using the Corvis ST. The biomechanical response of the cornea covered the following parameters: time to reach applanation (AT), length of the flattened segment in a Scheimpflug image (AL), and velocity of the corneal movement during applanation (AV), all at the moment of both the 1st and 2nd applanation events. Other parameters are the point of highest concavity ie; time (HcR), deformation amplitude (HdA), distance between bending points of the cornea (HpD) and concave radius of curvature (HcR).


The mean IOP in post DSAEK and post PK was approximately 1mmHg lower whilst the post DALK was 2 mmHg higher than normal eyes (p<0.05). The mean CCT of the post DSAEK eyes (628.4 ± 67.3) mm was significantly higher than normal subjects (528.2 ± 29.5mm, p<0.05). The post DALK group showed significantly higher HCT (mean difference; 0.53±0.13 s, p<0.05) and HdA (mean difference; 0.11±0.30 mm, p<0.05) whilst the HCR was lower compared to normal subjects (mean difference; 0.52±0.32mm, p<0.05). The post PK subjects was comparable to normal subjects, except for HCR (p<0.01).


Each group displayed different effect on all the Corvis ST parameters during different corneal deformation phase. The most affected corneal biomechanical parameter occurred during the highest corneal concavity phase.

Financial Interest:


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