Biomechanical properties of the cornea in Fuchs' corneal dystrophy

To investigate the effects of Fuchs' corneal dystrophy (FCD) on corneal biomechanical properties and the results of IOP readings in relation to changes in corneal hysteresis (CH) and central corneal thickness (CCT).

Corneal biomechanical properties, including CH, corneal resistance factor (CRF), and CCT, were measured with the ocular response analyzer (ORA) in 11 eyes of 11 patients with clinically confirmed FCD and 12 eyes of 12 healthy subjects. The ORA was also used to determine the values of intraocular pressure (IOP(g)) and corneal compensated IOP (IOP(cc)). Goldmann applanation tonometry (GAT) was also measured.

CH measured 10.3 +/- 1.6 mm Hg (range, 8.7-13.8) in normal eyes and 6.9 +/- 1.8 mm Hg (range, 4.6-11.7) in FCD eyes (P = 0.001). CRF in the normal and FCD eyes was 10.5 +/- 1.5 mm Hg (range, 8.5-13.3) and 8.1 +/- 1.9 (range, 4.5-11.2), respectively (P = 0.005). CCT was higher in FCD eyes (606 +/- 20 microm; range, 578-635) than in normal eyes (538.4 +/- 24.9 microm; range, 495-575; P = 0.0001). IOP(g) was 16.2 +/- 2.2 mm Hg (range, 13.5-18.7) in control eyes compared with 17.6 +/- 2.7 mm Hg (range, 12.8-18.6) in FCD eyes (P = 0.201). However, IOP(cc) in the FCD group (21.8 +/- 4.6 mm Hg; range, 12.8-29.0) was higher than in the control group (16.5 +/- 3.4 mm Hg; range, 11.9-23.9; P = 0.006). GAT in the normal and FCD eyes was 16.7 +/- 2.1 mm Hg (range, 12.8-18.6) and 16.9 +/- 2.3 mm Hg (range, 13.1-19.0), respectively (P = 0.205).

FCD led to a change of corneal biomechanical properties. CH and CRF were significantly lower in FCD eyes than in normal eyes. IOP(cc) was significantly higher in FCD eyes than in control eyes. These values may be useful in addition to CCT when assessing corneal rigidity. Thus, FCD may cause an underestimation error in IOP measurement.