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Comparison of biomechanical and tomographic data in subclinical keratoconus

Session Details

Session Title: Corneal biomechanics

Session Date/Time: Tuesday 08/10/2013 | 08:00-10:30

Paper Time: 09:54

Venue: Elicium 1 (First Floor)

First Author: : R.Vinciguerra ITALY

Co Author(s): :    R. Ambrosio   M. Romano   C. Azzolini   I. de Oliveira Ramos   S. Trazza   P.

Abstract Details

Purpose:

To evaluate the tomographic and biomechanical corneal changes in subclinical keratoconus (KC).

Setting:

Eye Center, Humanitas Clinical and Research Center, Rozzano (MI), Italy

Methods:

Ten patients with very asymmetric KC were retrospectively compared with fellow eyes without tomographic evidences of KC. Tomographic and biomechanical data were respectively obtained with Pentacam and Corvis ST (Oculus Optikgerate GmbH, Wetzlar, Germany). The eyes without tomographic evidences of KC were also compared with ten healthy subjects pachymetry- and intra ocular pressure (IOP)-matched. From Pentacam analysis we considered: minimal pachymetry, single and total deviation values (Dv) from Belin-Ambrosio Enhanced Ectasia Display (BAD), and all topometric indexes obtained in the topometric map. From Corvis ST analysis we considered: time (t1-2), length (l1-2) and velocity (v1-2) of first and second applanation, time (tC), peak distance (pC), radius (rC) and deformation amplitude (dC) of highest concavity, IOP and pachymetry.

Results:

Comparison between KC and the fellow eyes revealed a significant difference in all single and total Dv evaluated (p<0.05). Similarly topometric values showed a significant difference (p<0.05) between KC and fellow eyes in all indexes (p<0.05). Corvis ST analysis indicated non significant difference between KC and fellow eyes (p>0.05) in all parameters, except limited selected parameters showing that fellow eyes had the same pathological biomechanical behavior of the eyes with manifest disease, whereas tomographic analysis didn’t show any significant pathological changes. Comparison between KC patients’ "healthy" eyes and control group showed only scattered significant difference in topometric indexes but no significant difference in tomographic data and in BAD Dv; moreover the overall total Dv difference was not significant. Conversely biomechanical data revealed significant differences in t1-2(p=0.03 and p=0.02) , tC(p<0.01), rC(p<0.01), pC(p<0.001) and dC(p<0.01) between KC patients and control group.

Conclusions:

Biomechanical analysis with Corvis ST is able to show significant difference between normal eyes subclinical KC when normal tomographic data show normality or only small abnormalities. In conclusion Corvis ST could be a valid aid in the screening for the risk of ectasia in refractive surgery patients and for early diagnosis of KC.

Financial Interest:

... receives consulting fees, retainer, or contract payments from a company producing, developing or supplying the product or procedure presented