Correlation Between Corneal Biomechanics and Anterior Segment Parameters in Healthy Saudi Females

Background: The ocular response analyzer (ORA) can measure corneal hysteresis (CH), corneal resistance factor (CRF), Goldmann correlated IOP (IOPg) and corneal compensated intraocular pressure (IOPcc).1 Anterior segment parameters such as central corneal thickness (CCT), thinnest corneal thickness (TCT), apex corneal thickness (Apex CT), corneal volume (CV), anterior chamber depth (ACD), anterior chamber volume (ACV) and corneal astigmatism (CA) can be measured by Pentacam which is a Scheimpflug imaging device.2 Many studies 3-10 investigated the correlation between corneal biomechanics and anterior segment parameters in healthy eyes and demonstrated a strong correlation between CH, CRF with CCT. Hwang et al 2013 7 found that CV was positively correlated with CH, but not CRF. However, Çevik et al 2016 10 reported positive correlations between CH, CRF, and CV and negative correlations between CH, CRF and both of posterior steep and average posterior 𝐾 values. Hwang et al 2 did not show a significant association between CA and all the biomechanical properties. Conversely, Montard et al 4 reported a negative association between CA with CH and CRF. Therefore, there is still debate regarding evaluation of this relation. Up to our knowledge, the correlation between corneal biomechanics and anterior segment parameters in healthy eyes is never investigated in Saudi Arabia.The purpose of this study was conducted to evaluate the correlation between corneal biomechanics measured with ORA and anterior segment parameters assessed with Oculus Pentacam HR in healthy Saudi females.Methods: This study was a prospective, non-randomized, cross-sectional, observational and quantitative study. The study included 129 eyes of 129 healthy Saudi females from King Saud University, Riyadh, Saudi Arabia. The mean age was 19.87 ± 1.328 (18 – 29 years). All subjects underwent a comprehensive ophthalmologic examination including refraction, visual acuity measurement, slit-lamp biomicroscopic examination, IOP measurement with an air puffer tonometer, and funduscopy. In addition, anterior segment parameters were measured with Oculus Pentacam HR. Additionally, corneal biomechanical parameters were measured with ORA (Reichert Ophthalmic Instruments). All data was analyzed using a Statistical Package for the Social Sciences (SPSS) version 22.0 software (SPSS Inc., Chicago, II, USA). Associations between corneal biomechanical parameters and anterior segment parameters were analyzed by Pearson’s Correlation coefficients. P < 0.05 was considered a statistically significant.Results: In this study, mean (±SD) spherical equivalent (SE) was -1.62 ± 2.15 diopters and mean (±SD) CCT was 552.41 ± 58.90 μm. Mean (±SD) CH and CRF were 11.61 ± 1.80 and 11.26 ± 1.99 mm Hg, respectively. Correlation between ORA parameters and the anterior segment parameters using Pearson’s Correlation Coefficient for all eyes in this study showed only highly significant positive correlation between CCT and each of CH, CRF, IOP g (r = 0.381, P < 0.0001) (r = 0.395, P < 0.0001) (r = 0.304, P < 0.0001) respectively. On the other hand, no significant association was detected between IOP cc and anterior segment parameters in this study Conclusion: This work is the first one in Saudi Arabia to evaluate the correlation between corneal biomechanics and anterior segment parameters in healthy Saudi females. This study reported a positive correlation between CCT and each of CH, CRF, IOPg. Mild myopic eyes in this study showed a positive association between ASKV and each of CH and CRF. In addition, the mild myopic eyes demonstrated a positive relation between IOP g and ACV. Future prospective studies including males, different ethnic populations, different age groups with large sample sizes, using different imaging techniques, are recommended.