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Corresponding Author

Amro Abdullah Khalil Mohamed

Document Type

Original Article

Abstract

Background and Purpose: Many people seek LVC surgeries, with some complications that may develop after an intervention such as post-LASIK ectasia, studying corneal biomechanics before LVC surgeries would decrease similar complications and increase LVC surgery safety, especially in corneas with ectasia susceptibility. The goal of the study was to study corneal biomechanics using Corvis ST in corneas with tomographic ectasia susceptibility and identify the part corneal biomechanics play in ectasia identification. Study design: Cross-Sectional Clinical Study. Setting: The investigation was carried out at the Ophthalmology Department, Al-Azhar University hospitals, and the Research Institute of Ophthalmology.

Subjects: The study included 33 eyes of cases of tomographic ectasia susceptibility by pentacam selected from the refractive unit from cases seeking Laser Vision Correction (LVC) surgery.

Methods: All eyes were examined by Pentacam HR after a general examination was done and their D values were between 1.6 and 3 SD (Tomographic corneal ectasia susceptibility) to be involved in our study, Corneal biomechanical indices were assessed using Corvis ST.

Results: With 100% sensitivity, 30.8 % specificity, 69% positive value for prediction, 100% negative predictive value, and an overall accuracy of 72.7% with marginal agreement between the two, abnormal TBI can predict suspicious ectasia according to CCT. According to CCT, abnormal CBI can predict suspicious ectasia with 90% sensitivity, 30.8% specificity, 66.7% overall accuracy, 66.7% positive value for prediction, and 66.7% negative predictive value, with only marginal agreement between the two.

Conclusion: Morphological (Pentacam) and biomechanical (Corvis ST) studies utilizing Scheimpflug camera technology are highly valuable in identifying and diagnosing corneal ectasia in the Egyptian population. These investigations can also be crucial in screening for potential corneal ectasia and could maximize (LVC) safety. But it's not a good idea to rely just on the Corvis ST biomarker because the other two technologies will provide better results. Between Corvis ST indices, the TBI and CBI were the most reliable markers for keratoconus detection. If linked to corneal topography and optical coherence tomography, it might, therefore, be regarded as a suitable enhancing biomarker for selecting candidates for refractive surgery. Additionally, corneal thickness had a significant influence on both CBI and TBI.

Keywords

Corneal biomechanics, Corvis ST, Ectesia susceptibility

Subject Area

Ophthalmology

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