Intraocular pressure and corneal biomechanics in patients affected by myotonic dystrophy type 1

To compare corneal biomechanical properties in patients affected by Myotonic Dystrophy (DM1) with healthy subjects in order to better understand the underlying reasons for low intraocular pressure (IOP) values detected in DM1 eyes. in this retrospective, comparative study were included 41 eyes of 41 DM1 patients and 41 eyes of healthy subjects, age and sex matched, were included. All participants underwent a complete eye visit including Goldmann applanation tonometry (GAT), corneal biomechanical properties evaluation performed with Corvis ST (CST) and corneal morphological evaluation through Oculus Pentacam. In this study, GAT-measured IOP was significantly lower in DM1 patients (12.63 ± 2.12 mmHg) compared to controls (16.65 ± 2.24 mmHg) (p < 0.001). DM1 patients, compared to the healthy subjects, showed significant differences in many parameters related to the corneal deformation. In particular, DM1 patients displayed, among others, higher mean values of highest concavity deformation amplitude (1.19 mm vs. 1.04 mm) (p < 0.0008), of deflection amplitude measured at applanation 2 (0.15 mm vs. 0.11 mm) (p < 0.0008), deflection amplitude measured at highest concavity (0.98 mm vs. 0.87 mm) (p < 0.0008) and maximum length of deflection amplitude (1.05 mm vs. 0.88 mm) (p < 0.0008). The findings presented in this study suggest that the corneas of patients affected by DM1 are more susceptible to external stimuli than those of healthy subjects. Thus, GAT may underestimate IOP in DM1 patients due to altered corneal biomechanics. • What is known: Patients with myotonic dystrophy type 1 (DM1) typically present with low intraocular pressure (IOP) values, but the underlying pathophysiological mechanisms remain unclear. • What is new: This study demonstrates that corneas of DM1 patients exhibit significantly higher deformability compared to healthy subjects, as measured by Corvis ST biomechanical parameters. • Clinical significance: The increased corneal deformability suggests that IOP measurements obtained with Goldmann applanation tonometry in DM1 patients may represent an underestimation of true IOP values. • Practical implications: Physicians should be aware that apparently low IOP values in DM1 patients may not represent true hypotony and should exercise caution when screening for glaucoma in this population.