Characterization of in vivo biomechanical properties in macular corneal dystrophy.

PURPOSE: To measure and compare corneal biomechanics in patients with macular corneal dystrophy (MCD), those who underwent penetrating keratoplasty (PK) for MCD, and normal subjects.

DESIGN: Cross-sectional study.

METHODS: This study enrolled 24 eyes with MCD, 25 PK eyes 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 study groups were compared in CCT, CRF, CH, and IOP.

RESULTS: CCT was significantly lower in the MCD group (423±47 mμ) as compared to the PK group (541±31 mμ, P<0.001) and controls (540±26 mμ, P<0.001); meanwhile, this parameter was comparable between the PK and control groups (P=0.98). CRF did not differ between the MCD (8.34±2.12 mmHg) and PK (8.66±1.66 mmHg) groups (P=0.89); however, both these two groups had lower CRF values than the controls (9.76±1.83 mmHg, P=0.02). No significant difference was observed among the three groups in CH (P=0.13). IOP did not differ between the MCD (11.25±1.69 mmHg) and PK (12.0±2.67 mmHg) groups (P=0.95); the IOP values for both these groups, however, differed significantly from the controls (13.46±2.17 mmHg, P=0.006).

CONCLUSION: 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 those undergoing PK for this stromal dystrophy.