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Keratometric index variation in keratoconic eyes implanted with Intacorneal ring segments

Poster Details

First Author: C.Menezes PORTUGAL

Co Author(s):    J. Lemos   P. Rodrigues   R. Resende   P. Coelho   B. Vieira   R. Gonçalves

Abstract Details


To evaluate the effect of Intacs (Addition Technology Inc., Fremont, California, USA®) in the keratometric index of keratoconic eyes implanted with Intacs.


Department of Ophthalmology - Hospital Pedro Hispano, Matosinhos, Portugal


A retrospective analysis of 19 patients submitted to Intacs-SK and 30 controls was performed. The anterior radius of curvature (ARC), posterior radius of curvature (PRC), the ratio between ARC and PRC (RatioAP) and the “mean pupil power” (MPP) were registered. Corneal topographies were obtained with Sirius System (CSO, Florence, Italy). In all cases two segments were used. The fictitious keratometric index was calculated using the Gauss Formula and assuming the MPP as the true corneal power. All values were obtained for the central 3mm. Independent and paired t-test were used (p<0,05).


Between controls and keratoconic eyes before Intacs-SK implantation, both mean ARC and PRC were statistically different (p<0,05), respectively 7,51±1,42 and 6,78±0,52mm for ARC and 6,28±0,84 and 5,59±0,86mm for PRC. However, statistical differences were not found between them in relation to the RatioAP (1,27±0,28 vs. 1,23±0,16) and the Keratometric index (1,3321±0,0127 vs. 1,3321±0,0521). In keratoconic eyes, after a mean follow up of 9,47 months after Intacs implantation, the mean ARC increased to 7,26±0,56mm (p=0,000), while the mean PRC almost did not increase to 5,63±0,94 milímetros (p>0,05). The RatioAP reduced to 1,31±0,19 (p<0,05) and mean calculated KI reduced to 1,3285±0,0817 (p<0,05).


The anterior surface of the cornea appears to be significantly flattened after Intacs implantation, while the posterior surface remains relatively unchanged, with a consequent decrease corneal KI. This suggests that the standard QI may not be suitable for the calculation of the power after intraocular lens implantation of Intacs. No differences in KI were found between controls and keratoconic eyes in our study.

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