 - Outflow facility: Tonographic outflow facility C measurement will be performed using an electronic Schiøtz tonographer Model 720, Berkeley Bioengineering Inc, USA between 9:00 am -12:00 midday. The facility of outflow will be measured from the rate of decay of IOP in the supine position during application of a recording Schiøtz tonometer over a period of 4 minutes with a standard 5.5 gram weight. The R values of the curve at every 30-second time point will be manually entered into the McLaren tonography computer program. The program fits a second-degree polynomial by least squares to the nine data points and determines the best-fit values for time 0 and time 4 minutes by extrapolation. 