Abstract
Purpose: :
To establish and compare corneal biomechanical properties in normal eyes, eyes with clinical keratoconus and eyes with moderate-high congenital regular astigmatism.
Methods: :
This study comprised 178 eyes of 97 patients. First group of 23 patients with moderate-high congenital regular corneal astigmatism greater than 2 D (45 eyes, age: 34, 58 ± 7, 98). Second group of 19 patients with moderate-high acquired astigmatism due to keratoconus (34 eyes, age: 37, 85 ± 14, 5). Control group consisted of 55 healthy subjects (99 eyes, age: 39,16 ± 13,10) with refractive errors inferior to 2 D of myopia and 1 D of hyperopia or astigmatism. Central corneal thickness (CCT) was measured by ultrasonic pachimetry. Corneal biomechanical properties, including corneal hysteresis (CH), and corneal resistance factor (CRF), were measured using the Ocular Response Analyzer (ORA). The ORA also determinated the values of intraocular pressure (IOPg) and corneal compensated intraocular pressure (IOPcc).
Results: :
Data were analyzed by the analysis of variance (ANOVA). Multiple comparison means were obtained through the Tukey test. There were significant differences in CH, CRF, CCT (p<0,001) and IOPg (p = 0,001) among the three groups. However, no significant differences of IOPcc (p >0,05) were observed. There were no significant differences in CH, CRF, CCT, IOPg and IOPcc between the control group and the congenital astigmatic group. CH, CRF, CCT and IOPg were significantly lower in keratoconus eyes group than in control group and in the group with congenital astigmatism .There were no significant differences in IOPcc among the three groups.
Keywords: astigmatism • cornea: clinical science • intraocular pressure