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Danielle L. Miura, Tiago S. Prata, Paulo Schor; Correlation Between Corneal Topographic Parameters And Visual Outcomes In Patients With Different Stages Of Keratoconus. Invest. Ophthalmol. Vis. Sci. 2012;53(14):1109.
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We aimed to determine the correlation between corneal topographic parameters and visual outcomes in patients with different stages of keratoconus.
We reviewed all charts of keratoconus patients followed in a tertiary Eye Clinic between 01/2009 and 01/2011 (n=189 patients). Eyes that underwent laser or incisional surgery were excluded from the analysis. Clinical and demographic data were collected including age, gender refraction and best corrected visual acuity (BCVA) at last follow-up visit. Patients were divided in 2 groups according to the current optical correction used to achieve the BCVA: I - spectacles (with or without contact lenses); II - contact lenses only (poor vision with spectacles). The following topographic parameters were compared between groups and correlated with patient’s final BCVA (analyzed as a categorical variable using 20/60 as cut-off value): central keratometric curvature (Kc), maximun KC (Kmax) and I-S Value [difference between inferior and superior keratometric values in diopters (D) measured at 3 mm from the center]. Whenever both eyes were eligible, one was randomly chosen for analysis.
A total of 164 patients were included. Mean age was 31.8±9.8 years, with no significant difference between patients in groups I and II (30.4 vs 32.5 years, respectively; p=0.22). Patients in group II had significantly greater Kc (50.6 vs 48.1 D), Kmax (55 vs 51.6 D) and I-S Value (2.6 vs 1.6) measurements than patients in group I (p≤0.01; Mann-Whitney test). Multivariate logistic regression analysis revealed that Kmax was the only parameter significantly associated with final BCVA (OR, 1.11; 95% CI, 1.04-1.18; p20/60) decreased by 11% for each increase of 1 diopter in the Kmax. The other topographic parameters evaluated were not significant in this model (p>0.05).
In this large series of patients with different stages of Keratoconus, Kmax seemed to be the best parameter to differentiate those with good visual outcomes from those with visual acuity deterioration.
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