Study: Corneal hysteresis linked to optic nerve surface deformation in glaucoma patients

Among glaucoma patients, corneal hysteresis measurements may be associated with more deformation of the optic nerve surface during transient IOP elevations than other anterior segment parameters, a prospective study found.

Anthony P. Wells, MD, ChB, FRANZCO, and colleagues evaluated the relationships between corneal hysteresis and corneal thickness with acute IOP-induced optic nerve head surface deformation in 100 eyes of 100 subjects with or without glaucoma. Specifically, 38 eyes were glaucomatous and 62 control eyes were not. The investigators induced elevated IOP with a modified LASIK suction ring to an average of 64 mm Hg for less than 30 seconds in the right eye of each subject. At baseline, all eyes had a mean cup depth of 247 µm.

Both corneal hysteresis (P = .012) and central corneal thickness (P = .011) measurements were lower in the glaucoma group than in the control group during IOP elevation, the authors noted.

The investigators found no statistically significant differences in spherical equivalent, cylinder, axial length, optic disc size or ocular pulse amplitude between eyes in the glaucoma and control groups. In addition, they found no difference in the amount of IOP elevation between the two groups.

The average difference in mean cup depth from baseline to IOP elevation for all eyes was 33 µm, the authors reported.

After controlling for age, sex and glaucoma status, multiple variable analysis revealed a significant correlation between corneal hysteresis and mean cup depth increase (P = .032). However, there were no significant associations between optic nerve deformation and central corneal thickness, axial length, ocular pulse amplitude and spherical equivalent during transient IOP elevations, according to the study, published in the August issue of Investigative Ophthalmology & Visual Science.