Evaluation of corneal biomechanical properties in mustard gas keratopathy

Degenerative biomechanical factors and immunologic processes with effect on collagen and corneal reparative process are known as the main cause of ocular surface dysfunction in mustard gas keratopathy (MGK) and may cause changes in the corneal biomechanical values. Therefore, we evaluate corneal biomechanical properties of these patients.

This case-control study includes 61 chemical warfare victims with MGK. After omission according to our exclusion criteria, 88 eyes of patients with MGK were enrolled as the case group and also a group of 88 normal eyes, which were matched regarding their age and sex in the control group, were enrolled. Measurements of corneal biomechanical properties which reported by ORA and Corvis ST (CST) devices were compared. The SPSS software version 23.0 was used in the statistical analysis. For comparisons between groups, if the data had a normal distribution, were analyzed by Student's t-test and ANOVA, and if the data didn't have a normal distribution, Mann-Whitney U test, and Kruskal-Wallis were used. Furthermore, to identify a relationship between two groups of data Spearman's rank Correlation test was used. P value < 0.05 were considered statistically significant.

In the MGK group, A1 length (A1L), A1 velocity (A1V), A2 velocity (A2V), deformation amplitude (DA) and peak distance (PD) were higher than the control group (P < 0.001). However, the corneal hysteresis (CH) (P = 0.003), corneal resistant factor (CRF), non-corrected IOP (IOPnct), corrected IOP based on corneal thickness (IOPpachy), and central corneal thickness (CCT) were lower than the control group (P < 0.001). The visual acuity according to the LogMAR scale and severity of MGK was positively associated with IOPpachy and negatively associated with CH, CRF, CCT and highest concavity radius (Radius).

Measurement of corneal biomechanical properties may be, have a useful role in the classification, monitoring or diagnosis of MGK.