The quantitative ocular traits analyzed were; intraocular pressure (IOP) taken as the maximum observed and average value per patient (measured by Goldman applanation tonometry), cup:disc ratio taken as the worst eye and average per patient, and central corneal thickness (CCT) taken as average over both eyes (measured by ultrasound pachymetry- Tomey pachymeter SP-3000; Tomey USA, Phoenix, AZ). Although data were mostly complete for IOP and CDR, fewer data were available for CCT. These ocular traits were also measured in the 50 Southampton controls. Details are given in Table 2.
