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Prognostic factors related to visual acuity after intracorneal segment rings implantation in patients with corneal ectasia

Poster Details

First Author: A.El Aswad SPAIN

Co Author(s):    J. Alio   P. Pena   A. Vega Estrada        

Abstract Details


To evaluate the clinical outcomes 6 months after the implantation of different intracorneal segment rings (ICRS) in patients with corneal ectasia and to understand fundamental differences between good and bad cases.


Vissum Corporation, Alicante, Spain.


30 eyes of 23 patients with ages ranging between 10 and 54 years were included. All cases were diagnosed with corneal ectasia: 1 case of post-LASIK ectasia, 1 case of pellucid marginal degeneration and 28 cases of keratoconus. More than 30 optical and ophthalmological variables were measured pre and postoperatively. All cases presented central corneal thickness of more than 350 ?m. SPSS statistics software package version 17 was used for the statistical analysis.


We made a predictive model for the corrected distance visual acuity (CDVA) at 6 months after surgery, obtaining a successful value of r2 in the regression analysis (r2 = 0.728). The corrected distance visual acuity at 6 months was significantly correlated with preoperative variables used in this study P<0.001. Homoscedasticity of the model has been confirmed by the normality of the unstandardized residuals distribution (P=0.20) and the absence of influential points or outliers (mean Cook distance = 0.049, standard deviation = 0.058). Moreover, Durbin-Watson test = 2.29 showed a poor correlation between residuals. The lack of multicollinearity has also been confirmed (tolerance=0.95; variance inflation factor =1.053).


Aspects like corneal geometry, corneal biomechanics and ocular aberrometry are strongly associated with the final results in the surgical implantation of intracorneal segments. Some of the most important variables to take into account are mean keratometry, corneal asphericity, corneal resistance factors and pachymetry. The separated and combined effects of these variables and their relative weights are analyzed in the present study. FINANCIAL DISCLOSURE?: No

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