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Calculation of central corneal thickness before and after corneal collagen cross-linking for keratoconic patients using the Pentacam and ultrasonic pachymetry

Poster Details

First Author: A.Rashed EGYPT

Co Author(s):                  

Abstract Details


Compare the central corneal thickness (CCT) before corneal collagen crosslinking(CXL) and after the procedure 1 month,3 months and 6 months successively in keratoconic patients. Compare the CCT measurements taken with the pentacam and with the ultrasonic pachymeter during the same periods. Correlate the changes in visual acuity with the change in corneal thickness.


Magrabi Eye Hospital,Jizan,Saudi Arabia


50 eyes of 26 patients with mild keratoconus(simK readings 46-55 D, and corneal thickness ranging from 400-550 um) were subjected to CXL with riboflavin. Age group ranged from 16-30 years of age,24 patients had both eyes treated, and 2 patients had only one eye treated.26 eyes(52%) were for males and 24(48%) were for females. Preoperative best corrected visual acuity(BCVA) using Snellen acuity chart was ranging from 20/22 to 20/30. CCT was measured to the patients using Oculus Pentacam HR and Sonogage Corneo-Gage Plus ultrasonic pachymeter preoperatively,then at 1 month,3 months, and 6 months follow up visits successively.BVCA was also remeasured in every follow up visit simultaneously.


CCT measurements were reduced in 100% of eyes by an average of 50um(45-55um) at 1 month follow up and remained so at 3 months and 6 months follow up. The exception to this was 4 eyes(8%) who had severe corneal haze and oedema and the CCT readings increased 30 um in the first eye and 34 um in the second eye,then as edema resolved the thickness decreased again in the other two follow up visits. Comparing the pentacam and ultrasonic pachymetry,there was no significant difference in the measurements taken by both machines(P<.01).However the pentacam provided a more accurate test point than the manually used ultrasonic pachymeter in the follow up visits. Regarding the BCVA, there was mild improvement by 1 line in 3 eyes (6%),and 2 lines in 1 eye(2%).Otherwise no correlation was found between the change in corneal thickness and BCVA during the follow up visits.


There is standard reduction in CCT after CXL for mild keratoconic patients.No significant difference in the measurements obtained by the pentacam or the ultrasonic pachymeter,thus the latter can be used if the pentacam is not economically available for follow up visits to monitor corneal thickness. The visual improvement provided by CXL is very minimal. A wide scale multicenter study is recommended to confirm such results, as the scale of this study was limited in region and number. FINANCIAL INTEREST: NONE

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