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Biomechanical Properties and Central Corneal Thickness Measurements in primary Congenital Glaucomatous and Normal Eyes: a Comparative Study

Mohammad Reza Razeghinejad, Athar Zareei, Ramin Salouti

Abstract


The correct estimation of intraocular pressure (IOP) is the most important factor in the management of various types of glaucoma. Primary congenital glaucoma is a type of glaucoma that can cause blindness in the absence of control of the IOP. In this retrospective observational study, ninety-five eyes of 48 healthy eyes and 47 primary congenital glaucomatous (PCG) were included. Two groups were matched for age, sex, and Goldman applanation tonometry (GIOP). Corneal hysteresis (CH), corneal resistance factor (CRF), Goldman intraocular pressure measured by ORA (IOPg) and corneal compensated intraocular pressure (IOPcc) were measured in each patient using Ocular Response Analyzer(ORA). Central corneal thickness (CCT) was measured by ultrasonic pachymetry. For each patient one eye randomly selected. student t-test and analytical regression were used for statistical analysis. The two groups are matched for age (P=0.34), sex (P=0.47) a GIOP (P=0.17). Corneal hysteresis and CRF were significantly lower in PCG than in normal eyes (p < 0.0001), but CCT was significantly thicker in PCG than in normal eyes (p < 0.0001). The regression equation on the effect of CH, CRF and CCT on GIOP in the PCG group shown that the CH and CRF (p-value=0.001<0.01 and p-value<0.0001) also has a significant effect but CCT has not any significant effect (p-value=0.691>0.01). A significant decrease in CH and CRF was found in the PCG group compared to normal. In the PCG group, the CCT was greater than normal. these results showed the usefulness of biomechanical properties (CH, CRF) in order to interpret IOP measurements. GIOP measurement may not be confined to a consideration of CCT alone. A low CH and CRF values could be responsible for under-estimation of GIOP in PCG group, in comparison to normal.



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