Characterization of In Vivo Biomechanical Properties in Macular Corneal Dystrophy

Abstract

To measure and compare corneal biomechanics in patients with macular corneal dystrophy (MCD), versus those who underwent penetrating keratoplasty (PK) for MCD, versus normal subjects. Cross-sectional study. This study enrolled 24 eyes with MCD, 25 eyes that underwent PK in patients with preoperative diagnosis of MCD, and 28 normal eyes. The ocular response analyzer was used to measure corneal biomechanical properties, including corneal resistance factor (CRF) and corneal hysteresis (CH). Intraocular pressure (IOP) was measured using a Goldmann applanation tonometer, and central corneal thickness (CCT) was measured using an ultrasonic pachymeter. The CCT, CRF, CH, and IOP were compared among the study group. CCT was significantly lower in the MCD group (423 ± 47 mμ) than in the PK group (541 ± 31 mμ; P < .001) and the controls (540 ± 26 mμ; P < .001). Meanwhile, CCT was comparable between the PK and control groups (P= .98). CRF did not differ between the MCD (8.34 ± 2.12mm Hg) and the PK (8.66 ± 1.66mm Hg) groups (P= .89); however, both of these groups had lower CRF values than the control (9.76 ± 1.83mm Hg, P= .02) group. No significant differences were observed among the 3 groups in CH (P= .13). IOP values did not differ between the MCD (11.25 ± 1.69mm Hg) and PK (12.0 ± 2.67mm Hg) groups (P= .95); however, the IOP values for both of these groups differed significantly from those of the controls (13.46 ± 2.17mm Hg; P= .006). CRF was significantly reduced in MCD and did not return to normal values even after PK. The reduced corneal rigidity could result in underestimating IOP in patients with MCD and in those undergoing PK for this stromal dystrophy.