Purpose: To define an unconventional diagnostic factor for keratoconus and to assess the correlation between anterior and posterior corneal surfaces based on vectorial astigmatic analyses. Design: Observational descriptive comparative cross sectional study Method: This study included two hundred and forty-four eyes of 244 patients divided into groups; normal corneas, or controls (C, n [100]), fruste (FFKc, n [28]) and manifest keratoconus (Kc, n [116]). Full Ophthalmic examination was performed. All candidates were examined using a rotating Scheimpflug corneal tomographer (Pentacam; Oculus Optikgeräte GmbH, Wetzlar, Germany) to obtain corneal measurements. Astigmatic vector analyses were carried out according to the method proposed by Thibos. Results: The area under receiver operating characteristic curve (AUC) for posterior corneal APV between normal and manifest keratoconus was 0.73 (95% confidence interval): 0.66 - 0.80. By using ROC curve Sensitivity, Specificity, positive predictive value (PPV), negative predictive value (NPV) and accuracy at cutoff 0.30 were (65.0%, 80.0%, 78.9%, 66.1% and 73.1% respectively). As regard posterior corneal Blur; the AUC between normal and manifest keratoconus was 0.92 (95% confidence interval): 0.88 - 0.96. By using ROC curve Sensitivity, Specificity, PPV, NPV and accuracy at cutoff 6.65 were (85.3%, 89.0%, 90.0%, 84.0% and 86.1%) respectively. Conclusion: Vector analysis of posterior corneal astigmatism; APV and Blur, is a simple, friendly, objective and supplementary approach in the differentiation of normal from manifest keratoconus. Astigmatisms of anterior and posterior corneal surfaces are correlated, particularly among keratoconic corneas.
Emarah, S., Awad, E., Samra, W. A. A., & Khalaf, M. A. (2022). Astigmatic Vector Analysis of Posterior Corneal Surface; Healthy versus Keratoconic Corneas. Egyptian Journal of Ophthalmology, (Mansoura Ophthalmic Center), 2(1), 1-9. doi: 10.21608/ejomos.2022.94204.1031
MLA
Sally G. Emarah; Eman Awad; Waleed Ali Abou Samra; Mohamad Ahmad Khalaf. "Astigmatic Vector Analysis of Posterior Corneal Surface; Healthy versus Keratoconic Corneas", Egyptian Journal of Ophthalmology, (Mansoura Ophthalmic Center), 2, 1, 2022, 1-9. doi: 10.21608/ejomos.2022.94204.1031
HARVARD
Emarah, S., Awad, E., Samra, W. A. A., Khalaf, M. A. (2022). 'Astigmatic Vector Analysis of Posterior Corneal Surface; Healthy versus Keratoconic Corneas', Egyptian Journal of Ophthalmology, (Mansoura Ophthalmic Center), 2(1), pp. 1-9. doi: 10.21608/ejomos.2022.94204.1031
VANCOUVER
Emarah, S., Awad, E., Samra, W. A. A., Khalaf, M. A. Astigmatic Vector Analysis of Posterior Corneal Surface; Healthy versus Keratoconic Corneas. Egyptian Journal of Ophthalmology, (Mansoura Ophthalmic Center), 2022; 2(1): 1-9. doi: 10.21608/ejomos.2022.94204.1031