Corneal Topographic Versus Manifest Refractive Astigmatism In Patients With Keratoconus In North Africa : A Retrospective Study Of 104 Patients
Published 2025 - 43rd Congress of the ESCRS
Reference: PO947 | Type: Poster | DOI: 10.82333/v24g-f676
Authors: Aguenaou Sarah* 1 , hassan abdallah 1 , siham chariba 1
1ophtalmology b,her,rabat,Morocco
Purpose
To compare the subjective manifest astigmatism to the corneal topographic astigmatism in patients with keratoconus.
Setting
-Retrospective study of 104 patients with all stages of keratoconus between 6 and 29 years old
-The diagnosis of keratoconus was established on the basis of a clinical examination and corneal tomography (Pentacam HR ).
-Exclusion criteria included patients who had undergone corneal surgery or cross linking, post-traumatic cataract and corneal scarring.
-Cycloplegic refraction was performed, one eye at a time, by the same doctor in low lighting using a topcon KR 8900 kerato refractometer
Methods
-Topographic corneal astigmatism was compared and correlated to manifest refractive cylinder in terms of power and axis.
-The difference between Topographic Astigmatism and manifest refractive cylinder was correlated to the Kmax and the thinnest pachymetry location , as indicators of keratoconus severity.
-All data collected in the study were entered into an electronic database via Microsoft Excel 2016
-Correlations were examined with Spearman rank correlation test. The Wilcoxon signed-rank test was used to test the difference between the two groups , A low p-value less than 0.05 indicates that there is a statistically significant difference between the two groups
Results
There was a significant positive correlation between manifest refractive cylinder power and Topographic Astigmatism power (p = 0.001; r = 0.76). Topographic Astigmatism power was significantly higher than manifest refractive cylinder in our study .
A significant correlation was present between the axis of the Topographic Astigmatism and manifest refractive cylinder with the axis of the manifest refractive cylinder tending to be more vertical than the axis of Topographic Astigmatism.
Conclusions
There is a difference between the topographic astigmatism and manifest refractive cylinder whom tends to be less in power and the axis tends to be more vertical
These results may help clinicians to use topographic astigmatism as a tool to guide them in optimal correction of keratoconus patients.