Submitted on: 23 May 2003.
Revised on: 05 July 2003.
Accepted on: 16 August 2003.
___________________British Journal of Visual Impairment
Submitted on: 12 November 2001.
Revised on: 19 February 2002.
Accepted on: 03 March 2002.
___________________British Journal of Visual Impairment
Submitted on: 16 May 2017.
Revised on: 17 June 2017.
Accepted on: 14 August 2017.
___________________British Journal of Visual Impairment
Submitted on: 07 May 2004.
Revised on: 09 August 2004.
Accepted on: 18 September 2004.
___________________British Journal of Visual Impairment
Submitted on: 15 May 2015.
Revised on: 08 July 2015.
Accepted on: 04 August 2015.
___________________British Journal of Visual Impairment
Submitted on: 03 November 1999.
Revised on: 02 January 2000.
Accepted on: 31 January 2000.
___________________British Journal of Visual Impairment