Abstract
Purpose: :
To determine whether eyes with more advanced glaucomatous cupping have a thinner central cornea, higher intraocular pressure (IOP) and greater IOP fluctuation relative to fellow eyes with less cupping.
Methods: :
A comparative case series study was conducted in 43 patients with asymmetric cup to disc ratio (CDR) associated with glaucoma. Twenty–six matched control cases without evidence of glaucoma were also analyzed. Asymmetry in CDR was defined as an intereye CDR difference of greater than 0.2. All participants had central corneal thickness (CCT) measured using ultrasound pachymetry, and IOP measured using Goldmann applanation tonometry. All measurements were performed in a standardized fashion. The CCT data were analyzed for intereye differences by the paired Student’s t–test and the sign test. The mean IOP over time and IOP variation over time, as measured by standard deviation, were also analyzed for intereye differences.
Results: :
In patients with asymmetric CDR (N=43), the mean intereye CCT difference (CCTlarger CDR – CCTsmaller CDR) was –13.99 microns + 21.25 (P < 0.0001). The eyes with the larger CDR had a thinner cornea in 81% of cases (P < 0.0001). In normal subjects, there was no significant intereye difference in CCT. The eyes with the larger CDR had a higher mean IOP compared to fellow eyes with the smaller CDR (19.8 mm Hg vs 16.2 mm Hg, P < 0.0001). The mean IOP standard deviation was 5.1 mm Hg in the eyes with the larger CDR compared to 3.0 mm Hg in fellow eyes with the smaller CDR (P < 0.0001). The eye with the larger CDR had a greater IOP standard deviation in 76% of cases (P = 0.001).
Conclusions: :
In patients with asymmetric CDR associated with glaucoma, eyes with more glaucomatous cupping have a thinner central cornea, higher mean IOP, and greater IOP variation over time compared to fellow eyes with less cupping. Acknowledgements: F.P. Soans, A. Marcovitch, J. Eisengart, T. Guckian and C. Downs contributed to data collection and patient recruitment.
Keywords: intraocular pressure • cornea: clinical science • optic disc