Farshad Abedi1,2, Antonia Kolovos1, Anna Waldie1, Jude Fitzgerald2, Mona Awadalla1, Miriam Keane1, John Landers1,2, Jamie E Craig1,2

Purpose: To assess the association of corneal deformation dynamics with glaucoma progression, as determined by the rate of retinal nerve fiber layer (RNFL) loss, in glaucoma suspects and early manifest glaucoma patients.

Methods: In this prospective study, consecutive patients with optic discs suspicious for glaucoma, performed a Humphrey 24-2 SITA Standard Visual Field (HVF) test. Enrolment required a mean deviation better than -5dB and using Hodapp-Anderson-Parrish criteria, mild or no glaucoma changes on HVF. Corneal deformation dynamics were assessed with the Corvis ST, a tonometer with visualization and measurement of the corneal response to an air impulse. Patients underwent spectral-domain OCT of the RNFL at baseline, and then six-monthly for 3-5 years.

Results: Eighty-eight eyes of 88 patients with a mean age of 64.3±10 years were recruited. The mean baseline inferior and superior RNFL thicknesses were 131.0±21.5µm and 100.0±18.3µm. The mean rate of the faster RNFL loss, in the inferior or superior rim, was -1.80±2.0µm/year. The mean length of “applanation 2”, the applanated part of the cornea on its return from the concave to convex position after the air impulse, was 1.78±0.25mm. This length was significantly associated with the rate of the faster RNFL loss (Spearman’s rho test:P=0.004,r=0.30).

Conclusions: In this study, an increased length of “applanation 2” was associated with a faster rate of RNFL loss. Further confirmation of this result and multivariate analyses of covariates such as intraocular pressure and central corneal thickness are required. Such results may help individualise management of glaucoma suspects and early glaucoma patients.