Dynamic corneal biomechanics in different cell layers; in keratoconus and normal
Azam Alvani1 *, Hassan Hashemi1 , Mohammad Pakravan2 , Mirgholamreza Mahbod1 , Kazem Amanzadeh1 , Mohammad Amin Seyedian1 , Mehdi Yaseri3 , Ebrahim Jafarzadehpur4 , Akbar Fotouhi3
- Noor Ophthalmology Research Center, Noor Eye Hospital, Tehran, Iran.
- Ophthalmic Epidemiology Research Center, Shahid Beheshti University of Medical Sciences, Tehran, Iran.
- Department of Epidemiology and Biostatistics, School of Public Health, Tehran University of Medical Sciences, Tehran, Iran.
- Department of Optometry, School of Rehabilitation, Iran University of Medical Sciences, Tehran, Iran.
Abstract: This study aimed to determine the relationship between corneal cellular structures and biomechanical deformation parameters in keratoconus (KC) and healthy individuals.
Methods: In this case-control study, 29 eyes of 29 KC patients were age- and gender-matched with 28 eyes of 28 healthy individuals using frequency matching. Corneal cellular structures including the density of basal epithelial cell, anterior keratocyte, posterior keratocyte, and endothelial cell, the coefficient variation of endothelial cell size (CV), percentage of hexagonal endothelial cell (HEX%), and biomechanical deformation parameters derived from Corvis Scheimpflug Technology (Corvis ST) in KC and normal groups were compared and the relationship between cellular and biomechanical parameters were calculated.
Results: In the KC group, highest concavity (HC) delta arc length and delta arc length maximum were associated with endothelial cell density (Beta=-0.39, p=0.026; and Beta=-0.60, p˂0.001, respectively). Furthermore, there was an association between HC deflection length and HEX% (Beta=-0.67, p=0.001). In the normal group, HC delta arc length and HC deflection length were associated with endothelial cell density (Beta=0.46, p=0.016; and Beta =-0.51, p=0.012, respectively). HC time, HC deformation amplitude, and applanation 1 delta arc length were associated with CV (Beta=0.50, p=0.01; Beta=0.27, p=0.009; and Beta=-0.57, p=0.002, respectively). Applanation 1 and applanation 2 deformation amplitudes were associated with HEX% (Beta=-0.49, p=0.005; and Beta=-0.46, p=0.015).
Conclusion: Biomechanical deformation parameters correlated with endothelial cell properties in both KC and normal groups, indicating the importance of the integrity of endothelial cells in biomechanical properties of both KC and normal corneas.
